【外文文献翻译】化学工业

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化工专业英语课文翻译

Unit 5 Basic Chemicals基本化学品我们将化学工业部门分成两类，生产量较大的部门和产量较低的部门。

在产量高的部门中，各种化学品的年产量达上万吨至几十万吨。

结果这样所用的工厂专门生产某一个单个产品。

这些工厂的连续方式进行操作，自动化程度高（计算机控制）归类于产量高的部门有硫酸，含磷化合物，含氮化合物，氯碱及其相关化合物，加上石油化学品和商品聚合物（如聚乙烯）（生产部门）。

除商品聚合物外，其它的均为重要的中间体，或基本化学品。

这些基本化学品是其他许多化学品的生产原料，其他许多基本化学品的需求量很大。

相反，产量低的部门主要从事精细化学品的生产。

单个化学品的年产量只有几十吨到几千吨。

然而，与高产量的产品相比，这些产品单位重量具有很高的价值。

通常，精细化斜坡的生产与间歇方式操作在工厂中，而且这些工厂常进行多种产品的生产。

低产量生产部门生产农用化学品，染料，药品和特种聚合物（如聚醚醚酮）。

基础化学品在化学工业中得不到支持，它们不那么引人注意（如药品），有时候利润不很高。

其利润来自于经济盛衰时难以预测的周期。

这些基本化学品不被公众注意到和直接使用，因此其重要性常得不到理解。

即使在化学工业中，其重要性也得不到足够的重视。

然而，如果没有这些基本化学品，其他工业就不复存在。

基本化学品处于原料（及那些从地下通过采矿、开采或用泵抽出来的物质）和最终产品的中间位置。

基本化学品的一个显著的特征就是它们的生产规模，每一种（基本化学品）的生产规模都相当大。

图2-1表示在1993 年美国市场上的25 中化学品。

（为了使我们了解化学品的分类与生产量有关。

）通常，基本化学品生产于那些年产量上万吨的工厂。

年产量10 万吨的工厂每小时要生产1.25 吨。

基本化学品的另一显著重要的特征是其价格。

大多数价格相当便宜。

基本化学品工业所作的工作（或任务）是找到经济的途径将原来转变为有用的中间体。

生产厂家要对它们的产品收取较高的价格几乎没有余地，因此，那些最低费用生产产品的厂家可能获得的利润最高。

化工专业英语翻译

Unit 1Chemical Industry 化学工业Before reading the text below, try to answer following question: 1. When did the modern chemical industry start? 2. Can you give a definition for the chemical industry? 3. What are the contribution which the chemical industry has made to meet and satisfy our needs? 4. Is the chemical industry capital- or labor-intensive? Why? 1.Origins of the Chemical Industry Although the use of chemicals dates back to the ancient civilizations, the evolution of what we know as the modern chemical industry started much more recently. It may be considered to have begun during the Industrial Revolution, about 1800, and developed to provide chemicals roe use by other industries. Examples are alkali for soapmaking, bleaching powder for cotton, and silica and sodium carbonate for glassmaking. It will be noted that these are all inorganic chemicals. The organic chemicals industry started in the 1860s with the exploitation of William Henry Perkin’s discovery if the first synthetic dyestuff—mauve. At the start of the twentieth century the emphasis on research on the applied aspects of chemistry in Germany had paid off handsomely, and by 1914 had resulted in the German chemical industry having 75% of the world market in chemicals. This was based on the discovery of new dyestuffs plus the development of both the contact process for sulphuric acid and the Haber process for ammonia. The later required a major technological breakthrough that of being able to carry out chemical reactions under conditions of very high pressure for the first time. The experience gained with this was to stand Germany in good stead, particularly with the rapidly increased demand for nitrogen-based compounds (ammonium salts for fertilizers and nitric acid for explosives manufacture) with the outbreak of world warⅠin 1914. This initiated profound changes which continued during the inter-war years (1918-1939). 1．化学工业的起源尽管化学品的使用可以追溯到古代文明时代，我们所谓的现代化学工业的发展却是非常近代（才开始的）。

化工英文文献翻译

Heavy Oil Development Technology of Liaohe OilfieldHan Yun(Scientific Research Information Department Exploration&Development Research Institute，Liaohe Oilfield Company)Liaohe Oilfield，the largest heavy oil production base in China，features in various reservoir types，deep burial，and wide range of crude oil viscosity．For many years，a series of technologies have been developed for different oil products and reservoir types of the oilfield，of which water flooding，foam slug drive，steam stimulation，steam drive,and SAGD are the main technologies. After continuous improvement，they have been further developed and played an important role in the development of heavy oil in the oilfield．Liaohe Oilfield is abundant in heavy oil resources，46％ of the total proved reserves of Liaohe Oilfield Company. Horizontally the resources concentrates in the West Depression and the southern plunging belt of the Central Uplift in Liaohe Rift. Vertically,it is mainly distributed in Paleocene Shahejie Formation(ES). The distinctive geological feature of Liaohe 0ilfield is manifested in three aspects：first，the heavy oil reservoirs are deeply buried and 80％ of them are buried more than 900m deep；second，the heavy oil viscosity ranges widely．For most of the reservoirs．the dead oil viscosity ranges in 100～100000mPa·s with the maximum 650000mPa·s.Third the reservoir types are various with complicated oil—water relationship，most of the reservoirs are edge water and bosom water reservoirs and there are also edge water reservoirs，top water reservoirs and bosom water reservoirs．For more than 20 years of development，Liaohe Oilfield has developed series of heavy oil development technologies for different oil products and different types of reservoirs，such as water flooding, foam slug drive,steam stimulation steam drive and SAGD．The most difficult issues have been overcome in the development of the super heavy oil in deeper formation．which has maintained the annual heavy oil output at 8 million tons for many years in Liaohe Oilfield．Water flooding development technology for conventional heavy oil-type 1Based on heavy oil classification,the conventional heavy oil．type I refers to the heavy oil with viscosity ranging in 50～100mPa·s，taking up about 20％ of the proved oil reserves of the oilfield．The heavy oil reservoirs of this type are buried ranging from 1 500m to 2400m deep and are capable of flowing．Therefore，natural energy is utilized for conventional development and then water flooding technology is used．For example，the reservoir of $32 oil unit of Block Leng-43 is buried 1 650～l 940m deep with the average oil zone 87.7m thick and the oil viscosity in situ 58mPa·s．In 1992，the 141 m spacing square well pattern was adopted to develop the kind of reservoirs by utilizing natural energy and two sets of oil production zones．In 2004，water flooding technology was applied. Currently,the degree of reserve recovery reaches 14％．the annual oil recovery rate is 1％，and the ultimate recovery ratio is predicted to be as high as 22％．Technology of foam slug and for conventional heavy oil-type steam flooding for conventional heavy oil-type 2 The upper limit of viscosity for the conventional heavy oil—type IIis l 0000mPa·s(the dead oil viscosity in situ)．This kind of heavy oil is the dominant type of heavy oil in Liaohe Oilfield，accounting for 60％ of total proved reserves．The reservoir of such heavy oil is buffed 800-1 600m deep in genera1. At initial development stage, steam stimulation was carried out to develop this kind of reservoirs．In the higher cycles of steam flooding，the reservoirs with the heavy oil viscosity close to the lower limit of this kind of heavy oil are conversed into the steam drive development．Pilot tests of foam slug and steam flooding have conducted in Block Jin-90 and Block Qi-40 successfully,and they will be applied to the whole blocks in near future．The recovery factor is forecast to be up to 50％ ~60％．Steam stimulation technology for special heavy oilThe special heavy oil refers to the heavy oil with the viscosity ranging in 10000~50000mPa·s in situ,which takes up 10% of proved oil reserves of the oilfield. The reservoir of the kind of oil is buried ranging from 1400m to 1800m. Steam simulation technology is often applied to develop such reservoirs. However, technology of steam drive or SAGD are also under research and experiments for reservoirs of good quality.SAGD technology for super heavy oilThe super heavy oil reservoir refers to the heavy oil with dead oil viscosity in situ over 50000mPa·s, which accounts for 10% of proved reserves of the oilfield. Due to its extremely high viscosity, it is just developed for few years. For the massive super heavy oil reservoirs, SAGD can be applied in the late stage of steam stimulation. At present, good intermediate results have been obtained in SAGD pilot test in Block Du-84 of Guantao Formation, showing good prospect for application. Theyhave been applied in the whole block and the ultimate recovery factor is predicted to achieve 55%.ConclusionVarious technology should be applied to develop different types of heavy oil reservoirs. Besides the technologies mentioned above, the technologies of combustion in situ, flue gas drive, and steam foam drive are also under research currently. Therefore, various development technologies will be increasingly improved with the heavy oil development of Liaohe Oilfield.References[1] Wang Xu. 2006. Heavy Oil Development Technologies and Discussion on the Research Orientation in the Next Step. Petroleum Exploration and Development [J],33(4):484~490[2] Liu Junrong. The Paper Collection of Liaohe Oilfield Development Seminar[C]:Beijing, Petroleum Industry Press, 2002[3] Zeng Yuqiang. 2006. Heavy Oil steam Stimulation Review. Special Oil&Gas Reservoir[J], 13(6):5~9辽河油田的重油开发技术韩云（科研信息部门勘探和开发研究所、辽河油田公司）辽河油田，在中国最大的重油生产基地，在不同的储层类型，具有埋藏深，与原油粘度范围宽。

化学专业外文文献原稿和译文

外文文献原稿和译文原稿Facile synthesis of hierarchical core–shell Fe3O4@MgAl–LDH@Au as magnetically recyclable catalysts for catalytic oxidation of alcoholsA novel core–shell structural Fe3O4@MgAl–LDH@Au nanocatalyst was simply synthesized via supporting Au nanoparticles on the MgAl–LDH surface of Fe3O4@MgAl–LDH nanospheres. The catalyst exhibited excellent activity for the oxidation of 1-phenylethanol, and can be effectively recovered by using an external magnetic field.The selective oxidation of alcohols to the corresponding carbonyl compounds is a greatly important transformation in synthesis chemistry. Recently, it has been disclosed that hydrotalcite (layered double hydroxides: LDH)-supported Cu, Ag and Au nanoparticles as environmentally benign catalysts could catalyse the oxidation of alcohol with good efficiency. In particular, the Au nanoparticles supported on hydrotalcite exhibit high activity for the oxidation of alcohols under atmospheric O2 without additives. It has been extensively demonstrated that the activity of the nanometre-sized catalysts will benefit from decreasing the particle size. However, as the size of the support is decreased, separation using physical methods, such as filtration or centrifugation, becomes a difficult and time-consuming procedure. A possible solution could be the development of catalysts with magnetic properties, allowing easy separation of the catalyst by simply applying an external magnetic field. From the green chemistry point of view, development of highly active, selective and recyclable catalysts has become critical. Therefore, magnetically separable nanocatalysts have received increasing attention in recent years because the minimization in the consumption of auxiliary substances, energy and time used in achieving separations canresult in significant economical and environmental benefits.Magnetic composites with a core–shell structure allow the integration of multiple functionalities into a single nanoparticle system, and offer unique advantages for applications, particularly in biomedicine and catalysis. However it is somewhat of a challenge to directly immobilize hierarchical units onto the magnetic cores. In our previous work, the Fe3O4 submicro-spheres were first coated with a thin carbon layer, then coated with MgAl–LDH to obtain an anticancer agent-containing Fe3O4@DFUR–LDH as drug targeting delivery vector. Li et al. prepared Fe3O4@MgAl–LDH through a layer-by-layer assembly of delaminated LDH nanosheets as a magnetic matrix for loading W7O24as a catalyst. These core–shell structural nanocomposites possess the magnetization of magnetic materials and multiple functionalities of the LDH materials. Nevertheless, these reported synthesis routes need multi-step and sophisticated procedures. Herein, we design a facile synthesis strategy for the fabrication of a novel Fe3O4@MgAl–LDH@Au nanocatalyst, consisting of Au particles supported on oriented grown MgAl–LDH crystals over the Fe3O4 nanospheres, which combines the excellent catalytic properties of Au nanoparticles with the superparamagnetism of the magnetite nanoparticles. To the best of our knowledge, this is the first instance of direct immobilization of vertically oriented MgAl–LDH platelet-like nanocrystals onto the Fe3O4 core particles by a simple coprecipitation method and the fabrication of hierarchical magnetic metal-supported nanocatalysts via further supporting metal nanoparticles.As illustrated in Scheme 1, the synthesis strategy of Fe3O4@MgAl–LDH@Au involves two key aspects. Nearly monodispersed magnetite particles were pre-synthesized using a surfactant-free solvothermal method. First, the Fe3O4 suspension was adjusted to a pH of ca. 10, and thus the obtained fully negatively charged Fe3O4spheres were easily coated with a layer of oriented grown carbonate–MgAl–LDH via electrostatic attraction followed by interface nucleation and crystal growth under dropwise addition of salts and alkaline solutions. Second, Au nanoparticles were effectively supported on thus-formed support Fe3O4@MgAl–LDH by a deposition–precipitation method (see details in ESI).Fig. 1 depicts the SEM/TEM images of the samples at various stages of the fabrication of the Fe3O4@MgAl–LDH@Au nanocatalyst. The Fe3O4nanospheres (Fig. 1a) show asmooth surface and a mean diameter of 450 nm with a narrow size distribution (Fig. S1, ESI). After direct coating with carbonate–MgAl–LDH (Fig. 1b), a honeycomb like morphology with many voids in the size range of 100–200 nm is clearly observed, and the LDH shell is composed of interlaced platelets of ca. 20 nm thickness. Interestingly, the MgAl–LDH shell presents a marked preferred orientation with the c-axis parallel to, and the ab-face perpendicular to the surface of the magnetite cores, quite different from those of a previous report. A similar phenomenon has only been observed for the reported LDH films and the growth of layered hydroxides on cation-exchanged polymer resin beads. The TEM image of two separate nanospheres (Fig. 1d) undoubtedly confirms the core–shell structure of the Fe3O4@MgAl–LDH with the Fe3O4 cores well-coated by a layer of LDH nanocrystals. In detail, the MgAl–LDH crystal monolayers are formed as large thin nanosheet-like particles, showing a edge-curving lamella with a thickness of ca. 20 nm and a width of ca. 100 nm, growing from the magnetite core to the outer surface and perpendicular to the Fe3O4surface. The outer honeycomb like microstructure of the obtained core–shell Fe3O4@MgAl–LDH nanospheres with a surface area of 43.3 m2g_1 provides abundant accessible edge and junction sites of LDH crystals making it possible for this novel hierarchical composite to support metal nanoparticles. With such a structural morphology, interlaced perpendicularly oriented MgAl–LDH nanocrystals can facilitate the immobilization of nano-metal particles along with avoiding the possible aggregation.Scheme 1 The synthetic strategy of an Fe3O4@MgAl–LDH@Au catalyst.Fig. 1 SEM (a, b and c), TEM (d and e) and HRTEM (f) images and EDX spectrum (g) of Fe3O4 (a), Fe3O4@MgAl–LDH (b and d) and Fe3O4@MgAl–LDH@Au (c, e, f and g).Fig. 2 XRD patterns of Fe3O4 (a), Fe3O4@MgAl–LDH (b) and Fe3O4@MgAl–LDH@Au(c).The XRD results (Fig. 2) demonstrate that the Fe3O4@MgAl–LDH nanospheres are composed of an hcp MgAl–LDH (JCPDS 89-5434) and fcc Fe3O4 (JCPDS 19-0629). It canbe clearly seen from Fig. 2b that the series (00l) reflections at low 2θ angles aresignificantly reduced compared with those of single MgAl–LDH (Fig. S2, ESI), while the (110) peak at high 2θangle is clearly distinguished with relatively less decrease, as revealed by greatly reduced I(003)/I(110) = 0.8 of Fe3O4@MgAl–LDH than that of MgAl–LDH (3.9). This phenomenon is a good evidence for an extremely well-oriented assembly of MgAl–LDH platelet-like crystals consistent with the c-axis of the crystals being parallel to the surface of an Fe3O4core. The particle dimension in the c-axis is calculated as ~ 25 nm using the Scherrer equation (eqn S1, ESI) based on the (003) line width (Fig. 2b), in good agreement with the SEM/TEM results. The energy-dispersive X-ray (EDX) result (Fig. S3, ESI) of Fe3O4@MgAl–LDH reveals the existence of Mg, Al, Fe and O elements, and the Mg/Al molar ratio of 2.7 close to the expected one (3.0), indicating the complete coprecipitation of metal cations for MgAl–LDH coating on the surface of Fe3O4.The FTIR data (Fig. S4, ESI) further evidence the chemical compositions and structural characteristics of the composites. The as-prepared Fe3O4@MgAl–LDH nanosphere shows a sharp absorption at ca. 1365 cm_1 being attributed to the ν3 (asymmetric stretching) mode of CO32_ ions and a peak at 584 cm_1 to the Fe–O lattice mode of the magnetite phase, indicating the formation of a CO32–LDH shell on the surface of the Fe3O4 core. Meanwhile, a strong broad band around 3420 cm_1 can be identified as the hydroxyl stretching mode, arising from metal hydroxyl groups and hydrogen-bonded interlayer water molecules. Another absorption resulting from the hydroxyl deformation mode of water, δ(H2O), is recorded at ca. 1630 cm_1.Based on the successful synthesis of honeycomb like core–shell nanospheres, Fe3O4@MgAl–LDH, our recent work further reveals that this facile synthesis approach can be extended to prepare various core–shell structured LDH-based hierarchical magnetic nanocomposites according to the tenability of the LDH layer compositions, such as NiAl–LDH and CuNiAl–LDH (Fig. S3, ESI).Gold nanoparticles were further assembled on the honeycomb likeMgAl–LDH platelet-like nanocrystals of Fe3O4@MgAl–LDH. Though the XRD pattern (Fig. 2c) fails to show the characteristics of Au nanoparticles, it can be clearly seen by the TEM of Fe3O4@MgAl–LDH@Au (Fig. 1e) that Au nanoparticles are evenly distributed on the edgeand junction sites of the interlaced MgAl–LDH nanocrystals with a mean diameter of 7.0 nm (Fig. S5, ESI), implying their promising catalytic activity. Meanwhile, the reduced packing density (large void) and the less sharp edge of LDH platelet-like nanocrystals can be observed (Fig. 1c and e). To get more insight on structural information of Fe3O4@MgAl–LDH@Au, the HRTEM image was obtained (Fig. 1f). It can be observed that both the Au and MgAl–LDH nanophases exhibit clear crystallinity as evidenced by well-defined lattice fringes. The interplanar distances of 0.235 and 0.225 nm for two separate nanophases can be indexed to the (111) plane of cubic Au (JCPDS 89-3697) and the (015) facet of the hexagonal MgAl–LDH phase (inset in Fig. 1f and Fig. S6 (ESI)). The EDX data (Fig. 1g) indicate that the magnetic core–shell particle contains Au, Mg, Al, Fe and O elements. The Au content is determined as 0.5 wt% upon ICP-AES analysis.Table 1 Recycling results on the oxidation of 1-phenylethanol The VSM analysis (Fig. S7, ESI) shows the typical superparamagnetism of the samples. The lower saturation magnetization (Ms) of Fe3O4@MgAl–LDH (20.9 emu g_1) than the Fe3O4 (83.8 emu g_1) is mainly due to the contribution of non-magnetic MgAl–LDH coatings (68 wt%) to the total sample. Interestingly, Ms of Fe3O4@MgAl–LDH@Au is greatly enhanced to 49.2 emu g_1, in line with its reduced MgAl–LDH content (64 wt%). This phenomenon can be ascribed to the removal of weakly linked MgAl–LDH particles among the interlaced MgAl–LDH nanocrystals during the Au loading process, which results in a less densely packed MgAl–LDH shell as indicated by SEM. The strong magnetic sensitivity of Fe3O4@MgAl–LDH@Au provides an easy and effective way to separate nanocatalysts from a reaction system.The catalytic oxidation of 1-phenylethanol as a probe reaction over the present novel magnetic Fe3O4@MgAl–LDH@Au (7.0 nm Au) nanocatalyst demonstrates high catalytic activity. The yield of acetophenone is 99%, with a turnover frequency (TOF) of 66 h_1,which is similar to that of the previously reported Au/MgAl–LDH (TOF, 74 h_1) with a Au average size of 2.7 nm at 40 1C, implying that the catalytic activity of Fe3O4@MgAl–LDH@Au can be further enhanced as the size of Au nanoparticles is decreased. Meanwhile, the high activity and selectivity of the Fe3O4@MgAl–LDH@Au can be related to the honeycomb like morphology of the support Fe3O4@MgAl–LDH being favourable to the high dispersion of Au nanoparticles and possible concerted catalysis of the basic support. Five reaction cycles have been tested for the Au nanocatalysts after easy magnetic separation by using a magnet (4500 G), and no deactivation of the catalyst has been observed (Table 1). Moreover, no Au, Mg and Al leached into the supernatant as confirmed by ICP (detection limit: 0.01 ppm) and almost the same morphology remained as evidenced by SEM of the reclaimed catalyst (Fig. S8, ESI).In conclusion, a novel hierarchical core–shell magnetic gold nanocatalyst Fe3O4@MgAl–LDH@Au is first fabricated via a facile synthesis method. The direct coating of LDH plateletlike nanocrystals vertically oriented to the Fe3O4 surface leads to a honeycomb like core–shell Fe3O4@MgAl–LDH nanosphere. By a deposition–precipitation method, a gold-supported magnetic nanocatalyst Fe3O4@MgAl–LDH@Au has been obtained, which not only presents high 1-phenylethanol oxidation activity, but can be conveniently separated by an external magnetic field as well. Moreover, a series of magnetic Fe3O4@LDH nanospheres involving NiAl–LDH and CuNiAl–LDH can be fabricated based on the LDH layer composition tunability and multi-functionality of the LDH materials, making it possible to take good advantage of these hierarchical core–shell materials in many important applications in catalysis, adsorption and sensors.This work is supported by the 973 Program (2011CBA00508).译文简易合成易回收的分层核壳Fe3O4@MgAl–LDH@Au磁性纳米粒子催化剂催化氧化醇类物质一种新的核壳结构的Fe3O4@MgAl–LDH@Au纳米催化剂的制备只是通过Au离子负载在已合成的纳米粒子Fe3O4@MgAl–LDH球体的MgAl–LDH的表面上。

中英文文献以及翻译(化工类)

Foreign material：Chemical Industry1.Origins of the Chemical IndustryAlthough the use of chemicals dates back to the ancient civilizations, the evolution of what we know as the modern chemical industry started much more recently. It may be considered to have begun during the Industrial Revolution, about 1800, and developed to provide chemicals roe use by other industries. Examples are alkali for soapmaking, bleaching powder for cotton, and silica and sodium carbonate for glassmaking. It will be noted that these are all inorganic chemicals. The organic chemicals industry started in the 1860s with the exploitation of William Henry Perkin’s discovery if the first synthetic dyestuff—mauve. At the start of the twentieth century the emphasis on research on the applied aspects of chemistry in Germany had paid off handsomely, and by 1914 had resulted in the German chemical industry having 75% of the world market in chemicals. This was based on the discovery of new dyestuffs plus the development of both the contact process for sulphuric acid and the Haber process for ammonia. The later required a major technological breakthrough that of being able to carry out chemical reactions under conditions of very high pressure for the first time. The experience gained with this was to stand Germany in good stead, particularly with the rapidly increased demand for nitrogen-based compounds (ammonium salts for fertilizers and nitric acid for explosives manufacture) with the outbreak of world warⅠin 1914. This initiated profound changes which continued during the inter-war years (1918-1939).Since 1940 the chemical industry has grown at a remarkable rate, although this has slowed significantly in recent years. The lion’s share of this growth has been in the organic chemicals sector due to the development and growth of the petrochemicals area since 1950s. The explosives growth in petrochemicals in the 1960s and 1970s was largely due to the enormous increase in demand for synthetic polymers such as polyethylene, polypropylene, nylon, polyesters and epoxy resins.The chemical industry today is a very diverse sector of manufacturing industry, within which it plays a central role. It makes thousands of different chemicals whichthe general public only usually encounter as end or consumer products. These products are purchased because they have the required properties which make them suitable for some particular application, e.g. a non-stick coating for pans or a weedkiller. Thus chemicals are ultimately sold for the effects that they produce.2. Definition of the Chemical IndustryAt the turn of the century there would have been little difficulty in defining what constituted the chemical industry since only a very limited range of products was manufactured and these were clearly chemicals, e.g., alkali, sulphuric acid. At present, however, many intermediates to products produced, from raw materials like crude oil through (in some cases) many intermediates to products which may be used directly as consumer goods, or readily converted into them. The difficulty cones in deciding at which point in this sequence the particular operation ceases to be part of the chemical industry’s sphere of activities. To consider a specific example to illustrate this dilemma, emulsion paints may contain poly (vinyl chloride) / poly (vinyl acetate). Clearly, synthesis of vinyl chloride (or acetate) and its polymerization are chemical activities. However, if formulation and mixing of the paint, including the polymer, is carried out by a branch of the multinational chemical company which manufactured the ingredients, is this still part of the chemical industry of does it mow belong in the decorating industry?It is therefore apparent that, because of its diversity of operations and close links in many areas with other industries, there is no simple definition of the chemical industry. Instead each official body which collects and publishes statistics on manufacturing industry will have its definition as to which operations are classified as the chemical industry. It is important to bear this in mind when comparing statistical information which is derived from several sources.3. The Need for Chemical IndustryThe chemical industry is concerned with converting raw materials, such as crude oil, firstly into chemical intermediates and then into a tremendous variety of other chemicals. These are then used to produce consumer products, which make our livesmore comfortable or, in some cases such as pharmaceutical produces, help to maintain our well-being or even life itself. At each stage of these operations value is added to the produce and provided this added exceeds the raw material plus processing costs then a profit will be made on the operation. It is the aim of chemical industry to achieve this.It may seem strange in textbook this one to pose the question “do we need a chemical industry?” However trying to answer this question will provide(ⅰ) an indication of the range of the chemical industry’s activities, (ⅱ) its influence on our lives in everyday terms, and (ⅲ) how great is society’s need for a chemical industry. Our approach in answering the question will be to consider the industry’s co ntribution to meeting and satisfying our major needs. What are these? Clearly food (and drink) and health are paramount. Other which we shall consider in their turn are clothing and (briefly) shelter, leisure and transport.(1)Food. The chemical industry makes a major contribution to food production in at least three ways. Firstly, by making available large quantities of artificial fertilizers which are used to replace the elements (mainly nitrogen, phosphorus and potassium) which are removed as nutrients by the growing crops during modern intensive farming. Secondly, by manufacturing crop protection chemicals, i.e., pesticides, which markedly reduce the proportion of the crops consumed by pests. Thirdly, by producing veterinary products which protect livestock from disease or cure their infections.(2)Health. We are all aware of the major contribution which the pharmaceutical sector of the industry has made to help keep us all healthy, e.g. by curing bacterial infections with antibiotics, and even extending life itself, e.g. ß–blockers to lower blood pressure.(3)Clothing. The improvement in properties of modern synthetic fibers over the traditional clothing materials (e.g. cotton and wool) has been quite remarkable. Thus shirts, dresses and suits made from polyesters like Terylene and polyamides like Nylon are crease-resistant, machine-washable, and drip-dry or non-iron. They are also cheaper than natural materials.Parallel developments in the discovery of modern synthetic dyes and the technology to “bond” th em to the fiber has resulted in a tremendous increase in the variety of colors available to the fashion designer. Indeed they now span almost every color and hue of the visible spectrum. Indeed if a suitable shade is not available, structural modification of an existing dye to achieve this canreadily be carried out, provided there is a satisfactory market for the product.Other major advances in this sphere have been in color-fastness, i.e., resistance to the dye being washed out when the garment is cleaned.(4)Shelter, leisure and transport. In terms of shelter the contribution of modern synthetic polymers has been substantial. Plastics are tending to replace traditional building materials like wood because they are lighter, maintenance-free (i.e. they are resistant to weathering and do not need painting). Other polymers, e.g. urea-formaldehyde and polyurethanes, are important insulating materials f or reducing heat losses and hence reducing energy usage.Plastics and polymers have made a considerable impact on leisure activities with applications ranging from all-weather artificial surfaces for athletic tracks, football pitches and tennis courts to nylon strings for racquets and items like golf balls and footballs made entirely from synthetic materials.Like wise the chemical industry’s contribution to transport over the years has led to major improvements. Thus development of improved additives like anti-oxidants and viscosity index improves for engine oil has enabled routine servicing intervals to increase from 3000 to 6000 to 12000 miles. Research and development work has also resulted in improved lubricating oils and greases, and better brake fluids. Yet again the contribution of polymers and plastics has been very striking with the proportion of the total automobile derived from these materials—dashboard, steering wheel, seat padding and covering etc.—now exceeding 40%.So it is quite apparent even from a brief look at the chemical industry’s contribution to meeting our major needs that life in the world would be very different without the products of the industry. Indeed the level of a country’s development may be judged by the production level and sophistication of its chemical industry4. Research and Development (R&D) in Chemical IndustriesOne of the main reasons for the rapid growth of the chemical industry in the developed world has been its great commitment to, and investment in research and development (R&D). A typical figure is 5% of sales income, with this figure being almost doubled for the most research intensive sector, pharmaceuticals. It is important to emphasize that we are quoting percentages here not of profits but of sales income, i.e. the total money received, which has to pay for raw materials, overheads, staff salaries, etc. as well. In the past this tremendous investment has paid off well, leading to many useful and valuable products being introduced to the market. Examplesinclude synthetic polymers like nylons and polyesters, and drugs and pesticides. Although the number of new products introduced to the market has declined significantly in recent years, and in times of recession the research department is usually one of the first to suffer cutbacks, the commitment to R&D remains at a very high level.The chemical industry is a very high technology industry which takes full advantage of the latest advances in electronics and engineering. Computers are very widely used for all sorts of applications, from automatic control of chemical plants, to molecular modeling of structures of new compounds, to the control of analytical instruments in the laboratory.Individual manufacturing plants have capacities ranging from just a few tones per year in the fine chemicals area to the real giants in the fertilizer and petrochemical sectors which range up to 500,000 tonnes. The latter requires enormous capital investment, since a single plant of this size can now cost $520 million! This, coupled with the widespread use of automatic control equipment, helps to explain why the chemical industry is capital-rather than labor-intensive.The major chemical companies are truly multinational and operate their sales and marketing activities in most of the countries of the world, and they also have manufacturing units in a number of countries. This international outlook for operations, or globalization, is a growing trend within the chemical industry, with companies expanding their activities either by erecting manufacturing units in other countries or by taking over companies which are already operating there.化学工业1.化学工业的起源尽管化学品的使用可以追溯到古代文明时代，我们所谓的现代化学工业的发展却是非常近代（才开始的）。

化学工业中英文对照外文翻译文献

中英文对照外文翻译(文档含英文原文和中文翻译)译文：化学工业1. 化学工业的定义在本世纪初，定义出化学工艺制品的构成是不难的，因为那时制造出来的化学产品很有限，例如，强碱、硫酸溶液。

现在，千上万的化学品从天然材料中提炼出来，例如原油（某些领域）被加工成很多中间产品，可以作为消费品，或着转变成消费品。

困难是在于裁决那一部分的过程属于化学工业领域，举个例子来阐释这种情况，乳化油漆可以含有聚合物（聚乙烯树脂）/聚脂（乙烯基醋酸纤维）。

很明显的，人造聚乙烯树脂（或醋酸纤维）和它们的聚合物都是化工产品。

然而，如果油漆的合成和配制中含有聚脂，它是由多种化工加工产生的副产品，那它是属于化学工业产品还是装饰工业产品呢？办公多样化和各个工业领域的相似性造成的，是由于没有给化学工业简单定义。

相反，每一个办公个体搜集和出版关于工业生产的数据，将会给那些化工生产过程一个简单的定义。

在比较那些不同来源的统计信息的时候，这是需要铭记于心的。

2. 化学工业的需要化学工业与许多原材料的加工有密切关系。

如原油，首先要变成化工中间产品，然后被加工成各种各样的其他化工产品。

这些产品经常被用来生产消费产品，使得我们的生活更加舒适，或者在另外一些领域比如制药方面，用于保持我们身体健康。

每一个阶段产生的价值都被加入到产品中，而且它提供的这些附加价值远远超过了原材料价值和制造加工过程的成本，这样过程中就产生了利润。

这也是化学工业的目的所在。

在书中提出这样一个问题可能会很奇怪：“我们需要化学工业么。

”然而，如果尝试去回答这个问题就会得出：（1）化学工业活动的领域很广泛（2）它影响我们的日常生活（3）社会很需要化学工业我们的话题是回答这个问题化学工业对我们的贡献。

这些需要包括什么呢？新鲜的食物（和饮料）和健康是主要的。

其它我们考虑的还有服饰，住房，娱乐及交通运输。

1.食物。

化学工业对食物生产的主要贡献至少体现在三个方面。

首先，生产大量可用化肥代替作物生长需要的自然化肥（如氮、磷、钾），促使现代农业增产。

化学化工类外文翻译原文

化学化工类外文翻译原文Original Text:Chapter 1 Introduction1.1 BackgroundNuclear energy has been providing a significant share of the world’s electricity for more than half a century. Currently, nuclear power plants generate approximately 10% of the world’s electricity supply, with this figure increasing to over 30% in some countries such as France [1]. However, for nuclear energy to continue to be an important source of electricity in the future, the safe and efficient operation of nuclear power plants must be ensured. A key component of ensuring safe and efficient operation is the availability of inspection techniques that can detect defects, assess their severity, and monitor their growth over time.The presence of defects in materials used in nuclear power plants can arise from a number of sources including fabrication, welding, and service exposure. Defects can manifest themselves as a variety of features such as cracks, voids, inclusions, and inhomogeneities. Defects can be classified based on their size, shape, and orientation, with some defectsbeing more critical to the performance and safety of a component than others. For example, surface-breaking transverse cracks in pressure vessel components can be particularly critical since they can rapidly propagate under service loading and can lead to catastrophic failure if not detected and remedied in a timely manner [2].Inspection techniques used to detect and monitor defects in nuclear power plant components are continually evolving. Inspection methods have traditionally included visual examination, ultrasonics, radiography, and eddy current testing [3]. These techniques have proven reliable and effective, but have limitations such as the inability to inspect certain materials and geometries. In addition, advances in materials science and technology have led to the development of new materials with different physical and chemical properties that may not be well-suited to traditional inspection techniques. Therefore, there is a need to develop and optimize inspection techniques that are capable of detecting andmonitoring defects in advanced materials and structures.1.2 Objectives and ScopeThe primary objective of this chapter is to provide an overview of the different types of inspection techniques that are currently used in the nuclearpower industry for detecting, characterizing, and monitoring defects in materials and components. The chapter will discuss the limitations of current inspection techniques and the challenges associated with the inspection of advanced materials and structures. The chapter will also highlight recent developments in inspection techniques including the use of advanced sensors, imaging, and data analysis techniques.The scope of the chapter will cover a range of inspection techniques used in the nuclear power industry including visual examination, ultrasonics, radiography, eddy current testing, and other techniques such as thermography and acoustic emission testing. The chapter will focus on the application of these techniques to welds, pressure vessels, steam generators, and reactor components. The chapter will also briefly discuss the use of inspection techniques for other applications such as monitoring corrosion and degradation of materials.1.3 Organization of the ChapterThe remainder of this chapter is organized as follows. Section 2 provides an overview of visual examination and its application to the inspection of nuclear power plant components. Section 3 describes ultrasonic inspection techniques and their use in detecting and characterizing defects in materials and components.Section 4 discusses radiography and its use forimaging defects in materials. Section 5 covers eddy current testing and its application to the detectionof surface and subsurface defects. Section 6 provides an overview of other non-destructive evaluation techniques such as thermography and acoustic emission testing. Section 7 summarizes recent developments in inspection techniques including the use of advanced sensors and imaging techniques. Section 8 concludesthe chapter with a discussion of challenges and future directions in inspection technology for nuclear power plant components.中文翻译：第一章绪论1.1 背景核能已经为全球电力供应提供了半个多世纪的重要部分。

化学工程油气运输外文翻译外文文献英文文献

毕业设计（论文）外文翻译毕业设计（论文）题目：关于加油站及油罐车的油气回收外文翻译（一）题目：Mechanical Degradation and Changes in Conformation ofHydrophobically Modified StarchOSA改性淀粉的机械降解和结构变化外文翻译（二）题目：Preparation and Properties of Octenyl Succinic AnhydrideModified Early Indica Rice Starch辛烯基丁二酸酐（OSA）改性早籼淀粉的制备和性能低成本和高可靠的喷射压缩机采用油气回收领域，以解决生态问题，在开发节能技术。

一定的技术困难，但是，这个操作复杂设备在最佳条件下，即：有效的参数范围狭窄喷气熟悉设计压缩机遇到喷射压缩机启动和稳定运行的复杂性液体收益访问接收室。

血压波动也使自己感到液体喷射压缩机的运作产生负面影响。

在同时，压力和流量的变化是恢复，积累就业的运作系统的特点，石油和天然气的加工。

在这方面，要研究液体喷射压缩机的操作下变条件，包括该设备的监管。

OAO跟Orenburgneft “液体喷射压缩机的设计，开发与双流量喷嘴集结合可调驱动电源泵，使人们有可能以不同的尺寸和无量纲特征喷射装置。

液体喷射压缩机的实验研究进行了在一条长凳上安装的IM Gubkin俄罗斯石油和天然气的州立大学。

在这些调查过程中，添置介绍了液体喷射压缩机相似理论[1]。

喷射压缩机的基本组件如下：- 直接流喷嘴组，以确保工作液喷射形成与调节的可能性射流压缩部分，科里奥利和Boussienesq系数的直径;- 一个环形接收室的入口和出口之间的部分，以确保交付的介质转移到工作液喷射;- 在第一套可互换组件（不同的入口和出口之间的混合室内部的直径和长度），确保工作与正在传输介质液体混合，- 扩散器与一组可互换组件（不同的入口部分的内部直径），从而确保在气液混合物的流速减少。

化工专业及其材料的英语翻译

化工专业及其材料的英语翻译化工专业及其材料的英语翻译篇一：化工翻译Unit 1Chemical Industry化学工业1．化学工业的起源尽管化学品的使用可以追溯到古代文明时代，我们所谓的现代化学工业的发展却是非常近代（才开始的）。

可以认为它起源于工业革命其间，大约在1800年，并发展成为为其它工业部门提供化学原料的产业。

比如制肥皂所用的碱，棉布生产所用的漂白*，玻璃制造业所用的硅及Na2CO3. 我们会注意到所有这些都是无机物。

有机化学工业的开始是在十九世纪六十年代以William Hey Perkin 发现第一种合成染料—苯胺紫并加以开发利用为标志的。

20世纪初，德国花费大量资金用于实用化学方面的重点研究，到1914年，德国的化学工业在世界化学产品市场上占有75%的份额。

这要归因于新染料的发现以及硫酸的接触法生产和氨的哈伯生产工艺的发展。

而后者需要较大的技术突破使得化学反应第一次可以在非常高的压力条件下进行。

这方面所取得的对德国很有帮助。

特别是由于1914年第一次世界大仗的爆发，对以氮为基础的化合物的需求飞速增长。

这种深刻的改变一直持续到战后（1918-1939）。

1940年以来，化学工业一直以引人注目的速度飞速发展。

尽管这种发展的速度近年来已大大减慢。

化学工业的发展由于1950年以来石油化学领域的研究和开发大部分在有机化学方面取得。

石油化工在60年代和70年代的迅猛发展主要是由于人们对于合成高聚物如聚乙烯、聚丙烯、尼龙、聚脂和环氧树脂的需求巨大增加。

今天的化学工业已经是制造业中有着许多分支的部门，并且在制造业中起着核心的作用。

它生产了数千种不同的化学产品，而人们通常只接触到终端产品或消费品。

这些产品被购买是因为他们具有某些性质适合（人们）的一些特别的用途，例如，用于盆的不粘涂层或一种杀虫剂。

这些化学产品归根到底是由于它们能产生的作用而被购买的。

2．化学工业的定义在本世纪初，要定义是化学工业是不太困难的，因为那时所生产的化学品是很有限的，而且是非常清楚的化学品，例如，烧碱，硫酸。

应用化学外文翻译药物化学外文文献英文文献文献翻译

原文题目：Concentration of ﬂavonoids and phenolic compounds in aqueous and ethanolicpropolis extracts through nanoﬁltrationAbstractPropolis has a variable and complex chemical composition with high concentration of ﬂavonoids andphenolic compounds present in the extract. The extract varies with the solvent used in extraction. Ethanol extracts more phenolic acid and polar compounds than water. Before their use in industry, extracts must be concentrated but the use of high temperatures can degrade some compounds. Membrane pro-cesses is an option that allows concentration at low temperatures. Nanoﬁltration was carried out withaqueous and ethanolic extracts and each extract results in two distinct fractions: permeate and retentate. The capacity of the membrane to retain the compounds was veriﬁed by spectrophotometric analysis: for aqueous solution, the membrane retained around 94% of the phenolic compounds and 99% of the ﬂavonoids, while for the ethanolic solution these values were 53% and 90%, respectively. Ferulic acid retentionindex was 1.00 and 0.88 to aqueous and ethanolic solutions, respectively. Thus, the nanoﬁltration processshowed high efﬁciency in the concentration of propolis extracts.1 IntroductionOver the last few decades, interest in functional foods has beengrowing fast, leading to the discovery of new functional components or processes that can improve food processing, as well as products that may help to retard aging or avoid diseases. In this context, bee products have gained the attention of consumers and researchers, due to their chemical compositions and functional properties. Propolis is one of the bee products with functional properties, but it cannot be consumed as a food because it is a resinous substance. It is prepared from the buds and exudates of certain trees and plants. These substances are transformed by the addition of wax and the enzyme glucosidase present in the bee saliva in order to form propolis (Bankova et al., 2000; Park et al., 1998). The product obtained is used by honeybees to protect the hives against invaders and contamination, to seal holes and to maintain the temperature. Some important characteristics have been reported for thissubstance, such as anti-microbial and antioxidant effects, anesthetic properties and others. Due to these characteristics, which can bring health beneﬁts, propolis is considered a functional ingredient and is used in food, beverages, cosmetics and medicine to improve health and prevent diseases (Burdock, 1998; IFIC, 2009). There are over 150 constituents in propolis, including polyphenols, terpenoids, steroids and amino acids. Flavonoids are one of the most important groups and can represent around 50% of the propolis contents,depending on the region where it is collected, since its characterist ics is inﬂuenced by plants and weather (Krell, 1996; Park et al., 1998). Kumazawa et al. (2004) tested the antioxidant activity of propolis from various geographic origins and showed different activities for each sample. Other studies indicated that the propolis from Europe and China contained many kinds of ﬂavonoids and phenolic acids, whereas the Brazilian samples had more terpenoids and prenylated derivatives of p-cumaric acid (Bankova et al., 2000). Finally, each combination of compounds in the propolis of acertain origin can represent speciﬁc characteristics in the ﬁnal product.The most common propolis extracting process uses ethanol as the solvent. However, this has some disadvantages such as the strong residual ﬂavor, adverse reactions and intolerance to alcohol of some people (Konishi et al., 2004). Researchers and industry are interested in producing a new type of extract with the same compounds extracted by the ethanolic method, but without the disadvantages. Water has been tested as the solvent, but resulted in a product containing less extracted compounds (Park et al., 1998). Konishi et al. (2004) tested water with a combination of some tensoactive compounds to replace part of the alcohol used in propolis extraction and all the tests were efﬁcient in extracting it, and the product showed good anti-microbial activity.Depending on the application, the solvent in propolis extracts must be reduced or eliminated. The processes that are used today, as lyophilization, vacuum distillation and evaporation, have some disadvantages like the use of high temperatures and high energy consumption. Lyophilization requires large amounts of energy, since the sample needs to be maintained at À20 °C for at least 24 h, and energy is also required for the sublimation of the solvent used during preparation of the extract. Moreover, the method often requires a previous stage of concentration, maintaining the product at 70 °C until part of the solvent is evaporated.Vacuum distillation requires great amounts of energy to generate the vacuum, and can lead to loss of compounds of low molecular weight, which can be removed together with the solvent evaporated in the system. Evaporation maintains the extract underheating at 70 °C, until all the solvent is removed. This process, in addition to the high demand for energy, can degrade the ﬂavonoid and phenolic compounds in propolis, due to the temperature used. However, it is the process that gives greater ease of implementation in companies due to low cost on the equipment required compared with the previous cases. The use of membrane concentration processes has been growing due to certain advantages, such as: low temperatures, absence of phase transition and low energy consumption (Matta et al., 2004). This procedure is based on the principle of selective permeation of the solute molecules through semi-permeable, polymeric or inorganic membranes. The driving force for mass transfer across the membrane in most membrane processes, such as a microﬁltration, ultraﬁltration, nanoﬁltration and reverse osmosis is mechanical pressure (Maroulis and Saravacos, 2003). Nanoﬁltration is a unit operation that permits many applications, such as solvent recovery from ﬁltered oil, exchange of solvents in the che mical industry (Geens et al., 2006), concentration and puriﬁcation of ethanolic extracts of xantophylls, which is important in both the pharmaceutical and food industries (Tsui and Cheryan, 2007) and in wine concentration (Banvolgyi et al., 2006), as well as in juice concentration (Vincze et al., 2006) in the food industry.The objective of this study was to investigate the membrane concentration of propolis extracts using water and ethanol as the solvents, exclusively, verifying the quality of the concentrated products in terms of the retention of ﬂavonoids and phenolic compounds during processing. The process was evaluated according to the permeate ﬂux, inﬂuence of temperature and pressure and concentration factor. The results obtained for each solution were compared to verify the viability of developing a new propolis product, based on water as the solvent.2. Materials and methods2.1. PropolisRaw propolis was obtained from Apis mellifera beehives in the State of São Paulo, Brazil, and was acquired in a single batch, in order to minimize the variability associated with the vegetation used for its production and the weather conditions. It was stored underrefrigeration (4 °C) until use in the preparation of extracts.The propolis produced in this region is characterized as group 12 (Brazil has 12 different groups of propolis, with distinct characteristics) and presents a great amount of soluble substances, antimicrobial activity against Staphylococcus aureus and Streptococcus mutans and greater anti-inﬂammatory activity than samples from other parts of the country, which can be associated with the higher concentrations of ﬂavonoids and phenolic compounds found in this group (Park et al., 2002).The ethanolic propolis solution was prepared from crude propolis previously comminuted in a bench blender with a 500 W motor, homogenized, weighed on a semi-analytical balance and mixed with 80% ethanol. The mixture was kept at room temperature for 7 days and manually stirred once a day. After this period, the sample was centrifuged (Beckman –Allegra 25-R, Beckman Coulter, German) at 8800 g for 20 min. The supernatant was ﬁltered and refrigerated for 3 h at 4 °C and then ﬁltered again for wax removal. Finally, the esulting extract was stored at room temperature in the dark.Preparation of the aqueous solutions followed the same procedures, using deionized water. Each solution was prepared in a proportion of 20% propolis and 80% solvent. Both extracts were evaluated with respect to their ﬂavonoid and phenolic compounds contents, to be compared with the concentrated products.2.2. Determination of total ﬂavonoidsThe total ﬂav onoid content of the propolis solutions was determined by the aluminum complexation method (Marcucci et al., 1998). In this procedure, the extracted solutions were diluted in the proportion of 1:10 (0.5 mL) and mixed with 0.1 mL of 10% aluminum nitrate, 0.1 mL of 1 mol/L potassium acetate and 4.3 mL of 80% ethyl alcohol. The samples were kept at room temperature for 40 min and the absorbance read at 415 nm. Quercetin was used as the standard to produce the calibration curve. The mean of three readings was used and the total ﬂavonoid content expressed in mg of quercetin equivalents (mg/g).2.3. Determination of the phenolic compoundsThe polyphenols in the propolis solutions were determined by the Folin–Ciocalteau colorimetric method (Kumazawa et al., 2004). According to this procedure, the extracted solution was previously diluted in the proportion of 1:10 (0.5 mL) and then mixed with 0.5 mL of the Folin–Ciocalteau reagent and 0.5 mL of 10% Na2CO3. The absorbance was readat 760 nm after 1 h of incubation at room temperature. Gallic acid was used as the standard to produce the calibration curve. The mean of three readings was used and the total phenolic content expressed in mg of gallic acid equivalents (mg/g).2.4. HPLC determinationThe compounds present in the initial extract, permeate and concentrated products, were determined by HPLC as described by Parket al. (1998). Three hundred microliters of each solution were injected into a liquid chromatograph (Shimadzu, Tokyo, Japan) connected to a diode-array detector at 260 nm. The mobile phase was water/acetic acid (19:1, v/v) (solvent A) and methanol (solvent B), with a constant ﬂow rate of 1 mL/min. The gradient started at30% solvent B, passing to 60% at 45 min, 75% at 85 min, 90% at 95 min and back to 30% at 105 min. The column was maintained at a constant temperature of 30 °C and the chromatograms processed using the computer software Chromatography Workstation (Shimatzu Corporation, Tokyo, Japan). The initial and concentrated samples were diluted in 1.5 mL of distilled water and the permeate sample was injected without dilution. The following authentic standards of phenolic acids and ﬂavonoids (Extrasynthese, Genay, France) were examined: q-cumaric acid, ferulic acid, cinnamicacid, gallic acid, quercetin, kaempferol, kaempferide, apigenin, isorhamnetin, rhamnetin, sakuranetin, isosakuranetin, hesperidin, hesperetin, pinocembrin, chrysin, acacetin, galangin, myricetin, tectochrysin and artepillin C, as they correspond to the most usual compounds present in propolis.2.5. Membrane concentrationIn this study, the propolis extracts were concentrated using a tangential ﬁltration system on a pilot scale, with a nanoﬁltration membrane as seen in the schematic diagram shown in Fig. 1. The experiments were performed on pilot equipment that permits the batch circulation mode, which means that both permeate and concentrate could be carried back to the feed tank. The permeate was totally removed just in a single experiment, where it was necessaryto obtain the concentrated product of the process. The nanoﬁltra tion module is equipped with a NF90 membrane (Osmonics, Minnetonka, USA) which is composed of polyamide and polysulphone, with 0.6 m2 of ﬁltration area and 98% rejection of MgSO4 ina test performed by manufacturing with a spiral module at 20 °C and 6.0 bar. Approximately5.0 L of each solution permeated through the membrane over 30 min, this being the time necessary to complete the concentration in an open system, which means that the permeatewas removed from the process. In the trials the permeate was removed and the retentate re-circulated until a concentration factor of around four. The concentration factor is calculated according to Eq. (1):Fig. 1. Schematic diagram of the nanoﬁltration unit where Vf is the total volume used in the feed, Vc is the volume collected in the concentrate fraction and Fc is the concentration factor. Other experiments were carried out at different temperatures (20–45 °C) and pressures (2.0–5.0 bar), in order to evaluate the inﬂuence of these parameters on the permeate ﬂux and the concentrated product quality. In these experiments, both the permeate and retentate were maintained under re-circulation in closed systems. The permeate ﬂux was calculated acco rding to the following equation: J=Vp/t*Ap (2)where Vp is the permeate volume collected during the time intervalt and Ap is the membrane surface area of permeation. The quality of the ﬁltration process was measured according to the quantity of ﬂavonoids and phenolic compounds present in permeate, evaluated as described in Sections 2.2–2.4, and the efﬁciency was measured according to the ﬂux permeate rate and retention index. This index measures the relation between the amounts of the compound of interest in permeate and in the concentrated solution, which demonstrates the ability of the membrane to retain this compound under the experimentalconditions. The index is calculated according to Eq. (3), in which R is the retention index, Cp is the concentration of the compound of interest in the permeate, and Cr is the concentration of the same compound in the retentate:R=1-Cp/Cr (3)It is important to know the rate of fouling that occurs in the membrane process, and one way of measuring this is to compare the permeate ﬂux of the solution under study with the permeate ﬂux when water is used as feed solution, under different pressures. Usually a variation in system pressure will cause a change directly proportional to the perme ate ﬂux. The fouling inﬂuence was measured by comparison of the permeate ﬂux of the aqueous propolis extract with the ﬂux of distilled water only, increasing the pressure from 1.0 to 5.0 bar.3. Results and discussionThe membrane process was carried out with the aqueous and ethanolic solutions in a closed system, in which the retentate and permeate streams being conducted back and mixed in a feed tank isolated from the environment, to evaluate the variation in permeate ﬂux with time. The temperature was maintained at 20 °C and the pressure at 5.0 bar. The results are shown in Fig. 2.After stabilization of the process, the permeate ﬂux began to decrease, after around 15 min of processing. The rate of decrease was higher for the alcoholic extract than for theaqueous extract, evidencing a greater rate of fouling with the alcohol solution. After 20 min of processing, the permeate ﬂux tended to stabilize, that is, concentration polarization already occurred and fouling did not increase with time. The permeate ﬂux in the stable region was about 12.0 L/h m2and 25.0 L/h m2for alcoholic and aqueous solutions, respectively. The difference between the permeate ﬂux of these solutions can be explained by their different compositions: the alcohol extract contains more compounds of low molecular weight, thus its concentration is more difﬁcult to achieve, and this reduces the ﬂux rate. Some of these compounds form a kind of wax which can cause more fouling in membrane.Tsui and Cheryan (2007) used nanoﬁltration to puri fy alcoholic corn extracts in the production of xanthophylls, and obtained a permeate ﬂux of around 10.0 L/h m2when working at 27 bar and 50 °C. Hossain (2003) studied the membrane concentration of anthocyanins from blackcurrant pomace extracts using ultr aﬁltration, obtaining a maximum permeate ﬂux of 17.3 L/h m2 at 1.4 bar and 18 °C. Using nanoﬁltration a permeate ﬂux of 20 L/h m2 was obtained at 20 bar and 50 °C in the concentration of red wine (Banvolgyi et al., 2006). The red wine concentration process is important since it can be considered a similar process to the concentration of alcoholic propolis, considering that they have similar compounds in solution and use alcohol as the solvent. The similarities between the processes allow a comparison between results. Low pressures (around 6 bar) were used in the propolis concentration process, when compared to other processes cited in the literature, but even so the values obtained for the permeate ﬂux were similar to those obtained in the other processes. Therefore this process can be assumed to be viable, mainly because of the reduced energy requirements necessary to generate the lower pressure.The pressure adopted was not characteristic of nanoﬁltration processes, but was sufﬁcient to carry out this concentration procedure.Fig. 3 shows the difference between the curve of the permeate ﬂux for the aqueous propolis extract and the curve of the permeate ﬂux for distilled water to measure the degree of fouling in the process with the aqueous propolis solution.The difference between the permeate ﬂuxes of water and the propolis solution shows the amount of fouling in the process, under the same conditions of temperature and pressure. This parameter increased, reaching 32% at 5.0 bar. The procedure also provided information on how the ﬂux wasaffected by a pressure variation, showing t hat the ﬂux changed linearly with the pressure in the region studied. In this pressure range of operation, the concentrated products did not present signiﬁcant variation among the experiments.By increasing the temperature from 20 to 45 °C and maintaining the pressure at 6.0 bar it was possible to determine the relation ship between the temperature and the permeability of the mem brane. Permeate ﬂux increased proportionally, by around 8% per degree of temperature, as shown in Fig. 4. This result may be attributed to the effect of temperature on the viscosity of the solution. Also, the composition of the concentrated products obtained at different temperatures showed no signiﬁcant difference among them, thus, a higher ﬂux can be obtained by increasing the temperature.The initial solutions, permeates and concentrates obtained by nanoﬁltration in open system were all subjected to a spectrophotometric analysis as described in Sections 2.2 and 2.3. The results for the aqueous solution indicated that this permeate only contained small amounts of phenolic compounds and ﬂavonoids, while the permeate from the ethanolic solution showed greater amounts, mostly of low molar weight phenolic compounds. Considering the losses in the compounds of interest in the resulting permeate, as compared to the initial solution, it can be seen that the aqueous solution of propolis retained almost 99% of the ﬂavonoids and 84% of the phenolic compounds. However, for the ethanolicsolution, these values were 90% and 53% for the ﬂa vonoids and phenolic compounds, respectively,as shown in Table 1. The lower retention obtained can be explained by the occurrence of plasticization in the case of ethanolic solution. This phenomenon can cause a membrane swelling or dilation, which in turn can increase the membrane diffusivity and solubility, causing loss of compounds in process.The results for the determination of ﬂavonoids and phenolic compounds carried out by spectrophotometric methods were veriﬁed by HPLC analysis, as described in Secti on 2.4. The substances were identiﬁed by a comparison of their retention times and ultraviolet spectra with those of standards in the literature. Chromato grams were obtained from the initial aqueous extract, and from the concentrated and permeated products, which are represented in Fig. 5a–c, where the numbers 1–3 indicate the peaks identiﬁed in the HPLC analysis.Table 2 shows the results of the quantitative analysis for all samples from the aqueous propolis solution. Comparing these data, it can be seen that there were no losses of ferulic acid to the permeate and only 20% of the caffeic acid present in the initial solution was lost to the permeate, this compound thus being the most abundant in the concentrated extract, of the compounds identiﬁed. All the aqueous solutions showed peaks located in the region thatrepresents a retention time of up to 20 min. This occurred since the water, being a polar material, only extracts polar compounds. The last peak identiﬁed in the permeated solution, probably does not represent an isolated compound but interference in the system, since this compound was not present in the other chromatograms. Ferulic acid was not identiﬁed in the permeated solution, indicating that no losses to the permeate occurred. The other peaks in the chromatograms represented compounds that could not be identiﬁed according to the standards in the literature. The permeated solution showed a small amount of compounds in low con centration, allowing to verify the efﬁcacy of the membrane concentration process.Park et al. (1998) analyzed an aqueous propolis solution prepared in the laboratory, using HPLC, and obtained similar results to those presented in Fig. 5a, reporting peaks with low retention times that represent polar substances, and identifying the compounds quercetin and pinocembrin. In their experiment, the proportions of water and alcohol in the solvents for propolis extraction were varied. Initial solutions contained 0–90% of alcohol, through which it was demonstrated that increasing the proportion of alcohol in the solution also increased the amount ofextracted ﬂavonoids and phenolic compounds in the propolis.The chromatograms obtained for the ethanolic solutions are presented in Fig. 5d–f. It was possible to identify peaks in the ethanolic solution throughout the process. Compounds with a retention time greater than 20 min are apolar and were extracted by ethanol, this being an advantage of the use of this solvent as compared to water, which does not extract apolars. On analyzing the chromatogram it can be seen that a considerable amount of cumaric acid was lost to the permeate (peak number 2 in Fig. 5f). This acid belongs to the phenolic acid class and has a low molar weight, which could explain the low retention capacity of the membrane for this compound. The results of the spectrophotometric analysis shown in Table 1 indicate a loss of phenolic compounds to the permeate, accounting for the cumaric acid and other compounds not being identiﬁed by the HPLC method. Using the data given in Tables 2 and 3 the retention index could be calculated from Eq. (2). These results can be observed in Table 4. The retention indexes veriﬁed that the membrane process retained the compounds of interest better when using aqueous solutions, since this resulted in smaller losses of the compounds studied to the permeate, as compared to such losses when working with the alcoholic solution. Cumaric acid was an exception, since only 56% of this compound was not lost to permeate. Despite the loss of compounds, the values obtained represent a high retention index and verify that the nanoﬁltration process is appropriate for propolis extracts.During their study on the concentration of red wine by nanoﬁltration, Banvolgyi et al. (2006) obtained a retention index of 88% for total acids, 50% for free sulfuric acids and 93% for the total extracts. Tsui and Cheryan (2007), working with the puriﬁcation of xantophylls by nanoﬁltration obtained a retention index of 90% for total solids, 88% for proteins and 98% for xanthophylls, the major compound of their study.In the present study, the values obtained for the retention indexes were very similar tothose cited in the literature for similar processes..4 ConclusionsThe results showed that nanoﬁltration can be considered as a good alternative for concentrating propolis extracts, since the membrane retained most of the ﬂavonoids and phenolic compounds, which are of major importance to propolis quality. Particularly in the case of the aqueous extract, it could be considered that there was no loss of compounds to the permeate solution, since almost 100% of the major compounds were retained. In the experiments with alcoholic propolis, the losses were considerable but this is a consequence of the higher amount of compounds extracted by alcohol. However, the method can be used for alcoholic solution since almost 90% of the ﬂavonoids were retained. Application of this technology could increase the use of propolis in many industrial applications, it being feasible to use the aqueous extract in new research projects and in the development of new products with functional properties. Furthermore, this process allows removal of the solvent from the extract, reducing the disadvantages associated with using alcoholic extractions. It should be noted that compared with other concentration methods, in the membrane process the product is not submitted to high temperatures and there is no change in the physical state of the solvent, which means that the functional properties of the compounds of interest are preserved and the process as a whole is energy saving.译文题目：黄酮类化合物和酚类化合物在水中和乙醇蜂胶中通过纳滤膜的提取率关键词:蜂胶膜浓度黄酮类化合物酚类化合物纳滤摘要：蜂胶具有可变的、复杂的化学成分，且蜂胶中黄酮类化合物的浓度较高，酚类化合物存在于蜂胶萃取物。

毕业设计论文化学系毕业论文外文文献翻译中英文

毕业设计论文化学系毕业论文外文文献翻译中英文英文文献及翻译A chemical compound that is contained in the hands of the problemsfor exampleCatalytic asymmetric carbon-carbon bond formation is one of the most active research areas in organic synthesis In this field the application of chiral ligands in enantioselective addition of diethylzinc to aldehydes has attracted much attention lots of ligands such as chiral amino alcohols amino thiols piperazines quaternary ammonium salts 12-diols oxazaborolidines and transition metal complex with chiral ligands have been empolyed in the asymmetric addition of diethylzinc to aldehydes In this dissertation we report some new chiral ligands and their application in enantioselective addition of diethylzinc to aldehydes1 Synthesis and application of chiral ligands containing sulfur atomSeveral a-hydroxy acids were prepared using the literature method with modifications from the corresponding amino acids valine leucine and phenylalanine Improved yields were obtained by slowly simultaneous addition of three fold excess of sodium nitrite and 1 tnolL H2SO4 In the preparation of a-hydroxy acid methyl esters from a-hydroxy acids following the procedure described by Vigneron a low yield 45 was obtained It was found that much better results yield 82 couldbe obtained by esterifying a-hydroxy acids with methanol-thionyl chlorideThe first attempt to convert S -2-hydroxy-3-methylbutanoic acid methyl ester to the corresponding R-11-diphenyl-2-mercapto-3-methyl-l-butanol is as the following S-2-Hydroxy-3-methylbutanoic acid methyl ester was treated with excess of phenylmagnesium bromide to give S -11-diphenyl-3-methyl-12-butanediol which was then mesylated to obtain S -11-diphenyl-3-methyl-2-methanesulfonyloxy -l-butanol Unfortunately conversion of S-11-diphenyl-3-methyl-2- methanesulfonyloxy -l-butanol to the corresponding thioester by reacting with potassium thioacetate under Sn2 reaction conditions can be achieved neither in DMF at 20-60 nor in refluxing toluene in the presence of 18-crown-6 as catalyst When S -1ll-diphenyl-3-methyl-2- methane sulfonyloxy -l-butanol was refluxed with thioacetic acid in pyridine an optical active epoxide R-22-diphenyl -3-isopropyloxirane was obtained Then we tried to convert S -11-diphenyl-3-methyl-l2-butanediol to the thioester by reacting with PPh3 DEAD and thioacetic acid the Mitsunobu reaction but we failed either probably due to the steric hindrance around the reaction centerThe actually successful synthesis is as described below a-hydroxy acid methyl esters was mesylated and treated with KSCOCH3 in DMF to give thioester this was than treated with phenyl magnesium bromide to gave the target compound B-mercaptoalcohols The enantiomeric excesses ofp-mercaptoalcohols can be determined by 1H NMR as their S -mandeloyl derivatives S -2-amino-3-phenylpropane-l-thiol hydrochloride was synthesized from L-Phenylalanine L-Phenylalanine was reduced to the amino alcohol S -2-amino-3-phenylpropanol Protection of the amino group using tert-butyl pyrocarbonate gave S -2-tert-butoxycarbonylamino-3-phenylpropane-l-ol which was then O-mesylated to give S -2-tert-butoxycarbonylamino-3-phenylpropyl methanesulfonate The mesylate was treated with potassium thioacetate in DMF to give l-acetylthio-2-tert-butoxycarbonylamino-3-phenylpropane The acetyl group was then removed by treating with ammonia in alcohol to gave S -2-tert-butoxycarbonylamino-3-phenyl-propane-l-thiol which was then deprotected with hydrochloric acid to give the desired S-2-amino-3-phenylpropane-1-thiol hydrochlorideThe enantioselective addition of diethylzinc to aldehydes promoted by these sulfur containing chiral ligands produce secondary alcohols in 65-79 Synthesis and application of chiral aminophenolsThree substituted prolinols were prepared from the naturally-occurring L-proline using reported method with modifications And the chiral aminophenols were obtained by heating these prolinols with excess of salicylaldehyde in benzene at refluxThe results of enantioselective adBelow us an illustration forexampleN-Heterocyclic carbenes and L-Azetidine-2-carboxylicacidN-Heterocyclic carbenesN-Heterocyclic carbenes have becomeuniversal ligands in organometallic and inorganic coordination chemistry They not only bind to any transition metal with low or high oxidation states but also to main group elements such as beryllium sulfur and iodine Because of their specific coordination chemistry N-heterocyclic carbenes both stabilize and activate metal centers in quite different key catalytic steps of organic syntheses for example C-H activation C-C C-H C-O and C-N bond formation There is now ample evidence that in the new generation of organometallic catalysts the established ligand class of organophosphanes will be supplemented and in part replaced byN-heterocyclic carbenes Over the past few years this chemistry has become the field of vivid scientific competition and yielded previously unexpected successes in key areas of homogeneous catalysis From the work in numerous academic laboratories and in industry a revolutionary turningpoint in oraganometallic catalysis is emergingIn this thesis Palladium Ⅱ acetate and NN"-bis- 26-diisopropylphenyl dihydro- imidazolium chloride 1 2 mol were used to catalyze the carbonylative coupling of aryl diazonium tetrafluoroborate salts and aryl boronic acids to form aryl ketones Optimal conditions include carbon monoxide 1 atm in 14-dioxane at 100℃ for 5 h Yields for unsymmetrical aryl ketones ranged from 76 to 90 for isolated materials with only minor amounts of biaryl coupling product observed 2-12 THF as solvent gave mixtures of products 14-Dioxane proved to be the superior solvent giving higher yieldsof ketone product together with less biphenyl formation At room temperature and at 0℃ with 1 atm CO biphenyl became the major product Electron-rich diazonium ion substrates gave a reduced yield with increased production of biaryl product Electron-deficient diazonium ions were even better forming ketones in higher yields with less biaryl by-product formed 2-Naphthyldiazonium salt also proved to be an effective substrate givingketones in the excellent range Base on above palladium NHC catalysts aryl diazonium tetrafluoroborates have been coupled with arylboron compounds carbon monoxide and ammonia to give aryl amides in high yields A saturated yV-heterocyclic carbene NHC ligand H2lPr 1 was used with palladium II acetate to give the active catalyst The optimal conditions with 2mol palladium-NHC catalyst were applied with various organoboron compounds and three aryl diazonium tetrafluoroborates to give numerous aryl amides in high yield using pressurized CO in a THF solution saturated with ammonia Factors that affect the distribution of the reaction products have been identified and a mechanism is proposed for this novel four-component coupling reactionNHC-metal complexes are commonly formed from an imidazolium salt using strong base Deprotonation occurs at C2 to give a stable carbene that adds to form a a-complex with the metal Crystals were obtained from the reaction of imidazolium chloride with sodium t- butoxide Nal and palladium II acetate giving a dimeric palladium II iodide NHC complex The structure adopts a flat 4-memberedring u2 -bridged arrangement as seen in a related dehydro NHC complex formed with base We were pleased to find that chloride treated with palladium II acetate without adding base or halide in THF also produced suitable crystals for X-ray anaysis In contrast to the diiodide the palladium-carbenes are now twisted out of plane adopting a non-planar 4-ring core The borylation of aryldiazonium tetrafluoroborates with bis pinacolatoborane was optimized using various NHC ligand complexes formed in situ without adding base NN"-Bis 26-diisopropylphenyl-45-dihydroimidazolium 1 used with palladium acetate in THF proved optimal giving borylated product in 79 isolated yield without forming of bi-aryl side product With K2CO3 and ligand 1 a significant amount of biaryl product 24 was again seen The characterization of the palladium chloride complex by X-ray chrastallography deL-Azetidine-2-carboxylic acidL-Azetidine-2-carboxylic acid also named S -Azetidine-2-carboxylic acid commonly named L-Aze was first isolated in 1955 by Fowden from Convallaria majalis and was the first known example of naturally occurring azetidine As a constrained amino acid S -Azetidine-2-carboxylic acid has found many applications in the modification of peptides conformations and in the area of asymmetric synthesis which include its use in the asymmetric reduction of ketones Michael additions cyclopropanations and Diels-Alder reactions In this dissertation five ways for synthesize S-Azetidine-2-carboxylic acid were studied After comparing all methods theway using L-Aspartic acid as original material for synthesize S-Azetidine-2-carboxylic acid was considered more feasible All mechanisms of the way"s reaction have also been studied At last the application and foreground of S -Azetidine-2-carboxylic acid were viewed The structures of the synthetic products were characterized by ThermalGravity-Differential Thermal Analysis TG-DTA Infrared Spectroscopy IR Mass Spectra MS and 1H Nuclear Magnetic Resonance 1H-NMR Results showed that the structures and performances of the products conformed to the anticipation the yield of each reaction was more than 70 These can conclude that the way using L-Aspartie acid as original material for synthesize S -Azetidine-2-carboxylic acid is practical and effective杂环化合物生成中包含手性等问题如催化形成不对称碳碳键在有机合成中是一个非常活跃的领域在这个领域中利用手性配体诱导的二乙基锌和醛的不对称加成引起化学家的广泛关注许多手性配体如手性氨基醇手性氨基硫醇手性哌嗪手性四季铵盐手性二醇手性恶唑硼烷和过渡金属与手性配体的配合物等被应用于二乙基锌对醛的不对称加成中在本论文中我们报道了一些新型的手性配体的合成及它们应用于二乙基锌对醛的不对称加成的结果1含硫手性配体的合成和应用首先从氨基酸缬氨酸亮氨酸苯丙氨酸出发按照文献合成α-羟基酸并发现用三倍量的亚硝酸钠和稀硫酸同时滴加进行反应能适当提高反应的产率而根据Vigneron等人报道的的方法用浓盐酸催化从α-羟基酸合成α-羟基酸甲酯时只能获得较低的产率改用甲醇-二氯亚砜的酯化方法时能提高该步骤的产率从 S -3-甲基-2-羟基丁酸甲酯合成 R -3-甲基-11-二苯基-2-巯基-1-丁醇经过了以下的尝试 S -3-甲基-2-羟基丁酸甲酯和过量的格氏试剂反应得到 S -3-甲基-11-二苯基-12-丁二醇进行甲磺酰化时位阻较小的羟基被磺酰化生成 S -3-甲基-11-二苯基-2- 甲磺酰氧基 -1-丁醇但无论将 S -3-甲基-11-二苯基-2- 甲磺酰氧基 -1-丁醇和硫代乙酸钾在DMF中反应 20～60℃还是在甲苯中加入18-冠-6作为催化剂加热回流都不能得到目标产物当其与硫代乙酸在吡啶中回流时得到的不是目标产物而是手性环氧化合物 R -3-异丙基-22-二苯基氧杂环丙烷从化合物 S -3-甲基-11-二苯基-12-丁二醇通过Mitsunobu反应合成硫代酯也未获得成功这可能是由于在反应中心处的位阻较大造成的几奥斯塑手村犯体的合成裁其在不对称奋成中肠左用摘要成功合成疏基醇的合成路是将a-轻基酸甲酷甲磺酞化得到相应的磺酞化产物并进行与硫代乙酸钾的亲核取代反应得到硫酷进行格氏反应后得到目标分子p一疏基醇用p一疏基醇与 R 义一一甲氧基苯乙酞氯生成的非对映体经H侧NM吸测试其甲氧基峰面积的积分求得其ee值 3一苯基一氨基丙硫醇盐酸盐从苯丙氨酸合成斗3一苯基一氨基丙醇由L一苯丙氨酸还原制备氨基保护后得到习一3一苯基一2一叔丁氧拨基氨基一1一丙醇甲磺酞化后得到习一3一苯基一2一叔丁氧拨基氨基一1一丙醇甲磺酸酷用硫代乙酸钾取代后得匀一3-苯基一2一叔丁氧拨基氨基一1一丙硫醇乙酸酷氨解得习一3一苯基一2一叔丁氧拨基氨基一1一丙硫醇用盐酸脱保护后得到目标产物扔3一苯基屯一氨基丙硫醇盐酸盐手性含硫配体诱导下的二乙基锌与醛的加成所得产物的产率为65一79值为O井92手性氨基酚的合成和应用首先从天然的L一脯氨酸从文献报道的步骤合成了三种脯氨醇这些手性氨基醇与水杨醛在苯中回流反应得到手性氨基酚手性氨基酚配体诱导下的二乙基锌与醛的加成所得产物的产率为45一98值为0一90手性二茂铁甲基氨基醇的合成和应用首先从天然氨基酸绿氨酸亮氨酸苯丙氨酸和脯氨酸合成相应的氨基醇这些氨基醇与二茂铁甲醛反应生成的NO一缩醛经硼氢化钠还原得到手性二茂铁甲基氨基醇手性二茂铁甲基氨基醇配体诱导下的二乙基锌与醛的加成所得产物的产率为66一97下面我们举例说明一下例如含氮杂环卡宾和L-氮杂环丁烷-2-羧酸含氮杂环卡宾含氮杂环卡宾已广泛应用于有机金属化学和无机配合物化学领域中它们不仅可以很好地与任何氧化态的过渡金属络合还可以与主族元素铍硫等形成配合物由于含氮杂环卡宾不但使金属中心稳定而且还可以活化此金属中心使其在有机合成中例如C-H键的活化C-CC-HC-O和C-N键形成反应中有着十分重要的催化效能现有的证据充分表明在新一代有机金属催化剂中含氮杂环卡宾不但对有机膦类配体有良好的互补作用而且在有些方面取代有机膦配体成为主角近年来含氮杂环卡宾及其配合物已成为非常活跃的研究领域在均相催化这一重要学科中取得了难以想象的成功所以含氮杂环卡宾在均相有机金属催化领域的研究工作很有必要深入地进行下去本文研究了乙酸钯和NN双 26-二异丙基苯基 -45-二氢咪唑氯化物1作为催化剂催化芳基四氟硼酸重氮盐与芳基硼酸的羰基化反应合成了一系列二芳基酮并对反应条件进行了优化使反应在常温常压下进行一个大气压的一氧化碳14-二氧杂环己烷作溶剂100℃反应5h 不同芳基酮的收率达7690仅有微量的联芳烃付产物 212 反应选择性良好当采用四氢呋喃或甲苯作溶剂时得到含较多副产物的混合物由此可以证明14-二氧杂环己烷是该反应最适宜的溶剂在室温或0℃与一个大气压的一氧化碳反应联芳烃变成主产物含供电子取代基的芳基重氮盐常常给出较低收率的二芳基酮而含吸电子取代基的芳基重氮盐却给出更高收率的二芳基酮及较少量的联芳烃付产物实验证明2-萘基重氮盐具有很好的反应活性和选择性总是得到优异的反应结果在此基础上由不同的芳基四氟硼酸重氮盐与芳基硼酸一氧化碳和氨气协同作用以上述含氮杂环卡宾作配体与乙酸钯生成的高活性含氮杂环卡宾钯催化剂催化较高收率地得到了芳基酰胺优化的反应条件是使用2mol的钯-H_2IPr 1五个大气压的一氧化碳以氨气饱和的四氢呋喃作溶剂由不同的有机硼化合物与三种芳基重氮盐的四组份偶联反应同时不仅对生成的多种产物进行了定 L-氮杂环丁烷-2-羧酸L-氮杂环丁烷-2-羧酸又称 S -氮杂环丁烷-2-羧酸简称为L-Aze1955年由Fowden从植物铃兰 Convallaria majalis 中分离得到成为第一个被证实的植物中天然存在的氮杂环丁烷结构作为一种非典型的氨基酸已经发现 S -氮杂环丁烷-2-羧酸可广泛用于对多肽结构的修饰以及诸如不对称的羰基还原Michael 加成环丙烷化和Diels-Alder反应等不对称合成中的多个领域本文通过对 S -氮杂环丁烷-2-羧酸合成路线的研究综述了五种可行的合成路线及方法通过比较选用以L-天冬氨酸为初始原料合成 S -氮杂环丁烷-2-羧酸的路线即通过酯化反应活泼氢保护格氏反应内酰胺化反应还原反应氨基保护氧化反应脱保护等反应来合成 S -氮杂环丁烷-2-羧酸分析了每步反应的机理并对 S -氮杂环丁烷-2-羧酸的应用及前景给予展望通过热分析红外质谱核磁等分析手段对合成的化合物的结构进行表征结果表明所得的产物符合目标产物所合成的化合物的结构性能指标与设计的目标要求一致每步反应的收率都在70％以上可以判定以L-天冬氨酸为初始原料合成 S -氮杂环丁烷的路线方案切实可行。

化学工业英文文献及译文

化学工业英文文献及译文1. 引言化学工业是现代工业中的重要部分，涉及各种化学品的生产和应用。

在化学工业的发展过程中，英文文献起着重要的作用。

本文旨在介绍化学工业英文文献的特点和相关译文的编写。

2. 化学工业英文文献的特点2.1 多样性化学工业英文文献涉及广泛的领域和专业知识。

其中包括有机化学、无机化学、物理化学、分析化学、材料科学等多个学科。

因此，了解不同领域的英文文献对于从事化学工业的人员来说非常重要。

2.2 专业性化学工业英文文献通常具有较高的专业性和技术性。

这些文献常常包含复杂的化学方程式、实验方法和数据分析等内容。

因此，阅读和理解这些文献需要读者具备一定的化学知识和实验经验。

2.3 国际性化学工业英文文献是由世界各地的科学家和研究人员撰写的。

这使得这些文献具有很强的国际性，反映了化学工业领域的前沿研究和发展动态。

对于从事国际化学工业合作和交流的人员来说，了解和掌握这些英文文献非常重要。

3. 化学工业英文文献译文的编写3.1 译前准备在进行化学工业英文文献的翻译之前，译者应充分准备，了解相关的化学知识和专业术语。

阅读英文文献中的化学方程式、实验方法和数据分析等内容，并确保自己对这些内容有清晰的理解。

3.2 译文的准确性化学工业英文文献译文要准确无误，以保持原文的科学性和技术性。

译者应尽可能使用准确的翻译术语和表达方式，确保译文的准确性。

3.3 术语的翻译化学工业英文文献中经常出现大量的专业术语，对这些术语的准确翻译是译文质量的关键。

译者应尽量使用已被广泛接受的翻译术语，避免出现模棱两可或不准确的翻译。

3.4 结构的调整化学工业英文文献的结构常常较为复杂，译者在翻译过程中可以适当调整结构，使译文更符合汉语表达习惯。

但要保持原文的主要内容和逻辑关系不变。

4. 结论化学工业英文文献对于从事化学工业的人员来说具有重要的价值。

了解化学工业英文文献的特点和编写相关译文的技巧，可以帮助读者更好地理解和应用相关的化学知识。

化工英文文献翻译

Three Common Details of The Compressor Failure AnalysisCompressor Fault Analysis (1) - motor burnedMotor compressor (hereinafter referred to as the compressor) of the fault can be divided into motor failure and mechanical failure (including the crankshaft, connecting rod, piston, valve, cylinder head pad, etc.). Mechanical failure is often the motor overload or stall, is one of the main motor damage.Damage mainly to the motor stator winding insulation damage (short circuit) and the circuit and so on. Stator windings was found damaged hard time, could eventually lead to winding burned. Winding burned, cover up some cause or direct cause of the phenomenon of burning, making the subsequent analysis and cause investigation more difficult.However, the operation of the motor power input is inseparable from the normal, reasonable motor load, good heat dissipation and winding wire insulation layer of protection. From several aspects, not difficult to find reason than burnt windings are six: (1) abnormal load and stall; (2) Winding short circuit caused by metal shavings; (3) contactor problems; (4) Power phase and voltage abnormalities; (5) inadequate cooling; (6) compressor vacuum. In fact, many factors contributed to the more common motor damage.1. Abnormal loads and stallMotor load requirements, including compressed gas load and the load required to overcome mechanical friction. Pressure ratio is too large, or the pressure is too large, the compression process will be more difficult; and increased friction caused by lubrication failure, and extreme cases of motor stall, will greatly increase the electrical load. Lubrication failure, friction increases, is the leading cause of abnormal load. Back to the diluted lubricating oil, oil heat, oil coking deterioration and lack of oil and so will disrupt normal lubrication, leading to lubrication failure. Back to the diluted lubricating oil, affecting the normal friction surface film formation, or even washed away the original film, increasing friction and wear. Compressor overheating will cause the thinning or even high-temperature coking oil, affecting the normal film formation. System back to the oil well, the compressor short of oil, they can not maintain normal lubrication. High-speed rotating crankshaft, connecting rod piston speed movement, there is no friction surface protection film will quickly heat up, local high-temperature rapid evaporation of the oil or coke, to make it more difficult to lubricate the parts, a few seconds can cause severe localized wear. Lubrication failure, local wear, the need for greater torque to the crankshaft. Low-power compressor (such as refrigerators, home air conditioning compressor) as the motor torque, lubrication failure often occurs after the stall (the motor can not rotate) phenomenon, and enter the "stall - Thermal protection - Locked" death cycle, motor burn only a matter of time. The high-power semi-closed compressor motor torque large, local wear will not cause stall, the motor power will be within a certain range increases with the load, causing more serious wear and tear, and even lead to bite cylinder (live seca in cylinder), rod fracture and other serious damage.When the current stall (stall current) is about 4-8 times the normal running current. The moment of starting the motor, the current reached a peak close to or stall current.Because the resistance heat release proportional to the square with the current, start and stall when the winding current will heat up quickly. Thermal protection can protect the electrode in the stall, but generally will not have a response soon, can not prevent such frequent starting winding due to temperature changes. Frequent starts and abnormal load, so that the test winding subjected to high temperature will reduce the magnet wire insulation.In addition, the compressed gas with the compression ratio will be required to increase the load and pressure increases. Therefore, the high temperature compressor for low temperature, or low compressor for high temperature, will affect the electrical load and heat, is not appropriate, will shorten the electrode life.Winding insulation deterioration, if there are other factors (such as metal shavings form conductive loops, acid oil, etc.) with, it is easy to cause a short circuit and damage.2. Scrap metal caused by short circuitWinding metal particles are mixed and ground insulation value of the low short-circuit the culprit. The normal vibration of the compressor running, and every time you start winding by the magnetic force of the pipe, will promote inclusion in the winding and the winding metal shavings between the relative motion between the magnet wire and friction. Sharp edges will scratch the enameled metal shavings insulation, causing short circuits. Sources including the construction of metal debris left behind by the brass shavings, welding slag, compressor internal parts wear and damage (such as broken valves), the fall of the metal shavings and so on. For the closed compressor (including the closed scroll compressor), the metal shavings or broken, would fall on the winding. For semi-hermetic compressors, and some particles with the gas and oil flow in the system, and finally assembled in the magnetic winding; and some metal shavings (such as bearing wear and stator and rotor wear (sweep bore) is generated) will be directly on the winding. Winding metal shavings gathered after a short circuit is only a matter of time.Need to draw particular attention to the two-stage compressor. In the two-stage compressor, back to the normal gas and oil directly back into the first grade (low grade) cylinder, compressed by the pressure of the cooling tube into the motor winding cavity, and the general single-stage compressor and then as second-class (high pressure stage cylinder.) Back to the gas with oil, the compression process has been skating on thin ice, if there are back to liquid again, the first stage cylinder valve can easily be broken. Broken by the pressure valve can enter the winding tube. Therefore, the two-stage compressor than the single-stage compressors are more likely to electrical short circuit caused by metal shavings.Unfortunately, things tend to conspire a piece of the compressor in the boot of a problem when the news channels is often the oil burning. Severe wear of metal surfaces when the temperature is very high, while oil above 175 º C at the start of coking. System, if there is more moisture (vacuum pits not ideal, big oil and refrigerant water, negative pressure air into the return pipe burst, etc.), lubricants acid may occur. Acidic oil will corrode copper and winding insulation layer, on the one hand, it can cause copper plating phenomenon; on the other hand, this acid containing copper atoms very poor insulation properties of lubricating oil, provided the conditions for the winding circuit.3. Contactor problemContacts is an important component in the motor control circuit, one of the best selection of irrational destruction of the compressor can be. The right choice according to the load contacts are extremely important.Contactor must be able to meet the harsh conditions, such as rapid cycling, continuous overload and low voltage. They must have enough surface area to distribute the heat generated by the load current, contact material should be selected to start or stall in such circumstances to prevent high current welding.For safe and reliable, while the compressor contactor to disconnect the three-phase circuit. Copeland is not recommended way to disconnect the two-phase circuits.In the United States, Copeland approved contactor must meet the following four:• contactor must meet ARI Standard 780-78, "Standard for special access" provisions of the work and testing guidelines.• The manufacturer must ensure that the contacts at room temperature in the lowe st 80% of nameplate voltage can be closed.• When using a single contactor, the contactor must be greater than the motor nameplate rated current rating (RLA). Meanwhile, the contactor must be able to withstand motor stall current. If there are other loads downstream of the contactor, such as electrical fans, and so must also be considered.• When using two contactors, each contactor rating of the sub-winding stall must be equal to or greater than the rating of the compressor stall half-winding.Contacts can not be less than the rated current of the compressor nameplate rated current. Size small or poor quality of contact can not withstand the compressor starts, stall, and low voltage high current impact, single-phase or multiphase prone to contact bounce, the phenomenon of welding or even fall off, causing electrical damage.Contact jitter frequently start and stop the motor contactor. Frequent motor starts, a huge starting current and heat, will aggravate the winding insulation aging. Each time you start, the magnetic torque to the motor windings have small mobile and mutual friction. If there are other factors with (such as metal shavings, poor insulation oil, etc.) can easily lead to short circuits between windings. Thermal protection system is not designed to prevent such damage. In addition, the jitter of the contactor coil easy to failure. If you have contact with the coil is damaged, prone to single-phase state.If the small selection of the contactor, the contact arc, and can not afford to open due to the frequent instability of circulatory arrest or heat generated by the voltage control loop may be welded together or from the contact frame in the loss. Welding of the contacts will have a permanent single-phase state, the overload protection device continuously cycle on and off.Needs to be stressed is that after the welding contactor, disconnect the compressor contactor power dependence of all the control loop (such as high and low pressure control, hydraulic control, defrost control, etc.) will all fail, the compressor is unprotected state. Therefore, when the motor burned, check the contacts are essential processes. Contacts lead to motor damage is often forgotten as a major reason.Compressor Fault Analysis (2) - liquid strike1. Processes and phenomena(1) suction valves are breakingCompressed gas compressor is a machine. Typically, compressed air piston 1450 times per minute (half-closed compressor), or 2900 times (all closed compressor), a suction or exhaust to complete the process time is 0.02 seconds or less. Suction and discharge valve plate of the size of the aperture and the suction valve sheet flexibility and strength are designed in accordance with the gas flow. The force from the perspective of the valve, the gas flow impact force is relatively uniform.The density of the liquid is dozens or even hundreds of times the gas, and thus the momentum of the liquid flow much larger than the gas, the impact force is also much larger. Mixed with more droplets aspirated into the cylinder when the flow is two-phase flow. Two-phase flow in the suction valve chip is not only the impact of high intensity and frequency, as if the typhoon beat mixed with pebbles at the window, the destructive self-evident. Is the liquid suction valve are breaking hit one of the typical characteristics and processes.(2) rod fractureCompression stroke of the time about 0.02 seconds, while the discharge process will be more short-lived. Or liquid droplets in the cylinder must be in such a short period of time discharged from the vent, the speed and momentum is significant. The case of exhaust valve and the suction valve sheet film the same, the difference is limited piece exhaust valve plate and spring-bit support is not easy to break. The impact of serious, limit deformation plate will tilt.If the liquid does not evaporate and discharge time cylinder, piston near top dead center when the compressed liquid, due to a very short time, the compressed liquid the process seems to be hit, also came in the metal cylinder head knocking. Compressed liquid is a liquid hammer or another part of the process.Instantly generate high-pressure liquid hit the broken ring of the great, the beginning of the familiar rod bending or breaking, the other pieces of compression force (valve plate, disc pads, crankshaft, piston, piston pin, etc.) will also be deformed or damage, but often overlooked, or confused with the exhaust pressure is too high. Maintenance of the compressor, people will be very easy to find bent or broken connecting rod, and give replacement, and forget to check whether there are other parts of deformed or damaged, thus laying the seeds for future failure.Attack caused by the fracture fluid is different from the axle rod and piston cylinder bite, it can tell. First, the liquid hit causing rod bent or broken in the short span of time, the rod ends of the piston and crankshaft motion freely, and not generally cause serious wear and tear or bite cylinder axle. Despite the broken piece suction valve, the valve can cause debris occasionally serious scratch piston and cylinder surface, but scratch the surface caused by wear and lubrication failure is very different. Secondly, the liquid caused by rod fracture attack is caused by stress, the connecting rod and a compression feature off stubble. Although the bite cylinder piston rod after the squeeze is also likely to fracture, but only to be stuck in the cylinder piston. Link broken axle after more different, connecting rod and crankshaft are badly scratched, resulting in a broken force is shear stress, are not the same broken stubble. Finally, and bite-cylinder front axle, the motor overload, severemotor heating, thermal protection will be action.2. ReasonsObviously, the compressor can cause the liquid fluid is nothing more than hit several sources as follows: 1) back to the fluid, which flows back to the compressor from the evaporator liquid refrigerant or lubricating oil; 2) starts with a liquid foam; 3) compressor lubricant too much. This paper will analyze each of these types of reasons.(1) back to the liquidTypically, back to the compressor run-time solution is the evaporator liquid refrigerant in the suction line back to the compressor through the phenomenon or process.For the refrigeration system expansion valve, expansion valve back to liquid and is closely related to improper selection and use. Expansion valve selection is too large, too small to set superheat, temperature of installation method is not correct or damaged insulation wrap, expansion valve failure can cause back to the fluid. For a small refrigeration system using capillary, the increase will cause excessive fluid back to liquid.Hot gas defrost system using prone to back solution. Regardless of the heat pump reversing valve operation, or by cooling hot gas bypass valve operation, hot gas defrost the evaporator after the formation of large amounts of liquid, the liquid refrigerant in the subsequent start of the run both possible and return to the compressor.In addition, severe frost evaporator fan failure or deterioration of heat transfer, no evaporation will cause the liquid back to liquid. Cold storage temperature fluctuations can also cause frequent reaction failures caused by the expansion valve back to liquid.Back to the liquid medium caused the accident hit mostly in air-cooled type (referred to as air-cooled or air cooled) semi-hermetic compressors and single two-stage compressors, compressor cylinders because they are directly connected with the return pipe, and once back to the fluid, easily lead to fluid strike accidents. Even if the strike did not cause fluid to return fluid into the cylinder will be diluted or washed away the wall of the piston and cylinder lubricating oil, increased piston wear.For the return air (refrigerant vapor) cooled semi-closed and closed compressor, back to the liquid rarely cause fluid attack. But it will dilute the crankcase oil. Contains large amounts of liquid refrigerant in the oil viscosity is low, the friction surface can not form a sufficient oil film, resulting in rapid wear of moving parts. In addition, the refrigerant oil in the transport process in the case of boiling heat will affect the normal transport lubricants. The farther from the pump, the more obvious the more serious problems. If a serious motor side bearing wear, the crankshaft to the side of the settlement could easily lead to the stator and the motor burned sweep Church.Obviously, back to the liquid solution will not only lead to strike, but also the wear of lubricating oil dilution. Wear and current load the motor will be greatly increased, over time will cause motor failure.Difficult to avoid the return liquid cooling system, installation of gas-liquid separator and taking the time to stop using the control can prevent or reduce the harm back to liquid. (2) start with liquidReturn air-cooled compressor is started, the crankcase oil is called the phenomenon of severe blistering start with liquid. When starting with a blistering fluid in the oil sight glass can be clearly observed. Start with the root cause of liquid dissolved in oil and submergedin the oil following a large number of the refrigerant, the pressure suddenly decreases suddenly boiling and cause blistering oil. This phenomenon is similar to our daily lives and suddenly open the coke cola bottle bubble phenomenon. The length of the duration of foaming agent into the area and cooling, usually a few minutes or ten minutes. The surface of a large number of bubbles floating in the oil, and even filled the crankcase. Once the cylinder through the suction inlet, the bubble will be reduced to liquid (a mixture of oil and refrigerant) can easily lead to fluid attack. Obviously, start with a liquid solution due to hit only occurs during the startup process.And back to the liquid is different from cause to start with liquid refrigerant is "refrigerant migration" of the way into the crankcase. Refrigerant migration is the compressor stops running, the evaporator refrigerant in gaseous form, through the trachea way back into the oil absorbed by the compressor or condensing in the compressor oil after mixing with the process or phenomenon.After the compressor is stopped, the temperature will decrease, and the pressure will rise. As the refrigerant vapor lubricant points down, it will absorb the oil surface of the refrigerant vapor, causing crankcase pressure lower than the evaporator pressure phenomenon. Lower oil temperature, the lower the vapor pressure of refrigerant vapor in the greater absorption of force. Evaporator to the crankcase vapor will slowly "migrate." In addition, if the compressor outside, cold weather or at night, the temperature is often lower than the indoor evaporator, the crankcase pressure there is low, the refrigerant can easily migrate to the compressor and into oil by condensation.Refrigerant migration is a very slow process. The longer the compressor is stopped, migrated to the oil in the refrigerant with it. Exist as long as the evaporator liquid refrigerant, this process will be conducted. As the refrigerant dissolved heavy oil, it will sink to the bottom of the crankcase, and oil floating in the above can also absorb more refrigerant.In addition to outside attack likely to cause liquid refrigerant migration will dilute the lubricating oil. Is very dilute oil pump to the friction surface, rinse out the original film may be washed, causing severe wear (a phenomenon often called refrigerant erosion). Wear transition with the gap will become larger, causing oil spills, thus affecting distant parts of the lubrication oil pressure will cause serious protection action.Due to structural reasons, the air-cooled compressor starts reducing crankcase pressure will be much slower, not very severe blistering, the bubble is difficult to enter the cylinder, air-cooled compressor so there is no problem with liquid starting fluid attack.In theory, the compressor crankcase heater installed (electric heater) can effectively prevent refrigerant migration. Short stop (eg at night), the crankcase heater to maintain power, the system can make the oil temperature is higher than other parts, refrigerant migration does not occur. No downtime (such as a winter), the heating oil before you start a few or ten hours, to evaporate the majority of oil in the refrigerant fluid can either start with a greatly reduced possibility of liquid strike , which also can reduce the harm caused by erosion of refrigerant. However, the actual application, the heater power to maintain after the shutdown or give ten hours before the heater power supply is difficult. Therefore, the practical effect of the crankcase heater will be greatly reduced.For larger systems, shut down before the evaporator to the compressor pumping liquidrefrigerant (known as taking the time to stop), can fundamentally prevent refrigerant migration. The pipe on the way back to the installation of gas-liquid separator, refrigerant migration can increase the resistance and reduce migration.Of course, by improving the compressor structure, can prevent refrigerant migration and reduce oil foaming degree. By improving the return-air-cooled compressor oil return path in the motor crankcase cavity and increased channel migration points (back pumps, etc.), you can cut off the access road after the shutdown, the refrigerant can not enter the crankshaft chamber; reduced intake Road and cross the channel to the crankcase when the crankcase pressure to slow down the boot speed, then control the degree of foaming and foam into the cylinder volume.(3) too much oilSemi-hermetic compressors usually have the oil sight glass to observe the oil level. Oil sight glass oil level above the range, indicating that the oil too much. Oil level is too high, high-speed rotation of the crankshaft and connecting rod may hit oil level frequently, causing a lot of splash oil. Once the oil splash fleeing into the inlet, into the cylinder, causing fluid to be hit.Large refrigeration system installation, they often need to add the appropriate lubricant. But for the poor oil return system, to seriously affect oil return to find the root causes of, and blindly added oil is dangerous. Even if the oil level being low, but also pay attention to sudden and large returns lubricating oil (such as after defrost) may cause danger. Attack caused by liquid lubricants are not uncommon.Compressor Failure Analysis (3) - lack of lubrication and lack of lubrication1. Lack of oilLack of oil is very easy to identify one of the compressor failure, compressor short of oil in the crankcase oil when little or no oil.Compressor is a special pump, a large number of refrigerant gas being discharged from the folder and also take a small portion of oil (known as Ben oil or an oil spill.) Ben compressor oil is inevitable, but Ben is different oils speed. Semi-sealed piston compressor discharge in about 2-3% of the oil, while the scroll compressor is 0.5-1%. For a displacement 100m3/hr, crankcase oil storage capacity of 6 liters of 6-cylinder compressor, 3% of the rush of oil means that about 0.3-0.8 liters / minute Ben oil, or running back to the oil-free compressor time for ten minutes.Discharge of the compressor oil does not return, the compressor will be short of oil. Compressor oil return in two ways, one is the oil separator oil return, the other is the return pipe back to the oil. Oil separator installed in the compressor discharge pipe on the road, generally isolated from 50-95% of the Ben oil, back to better effect, fast, greatly reducing the amount of oil into the system piping, which effectively extended the running time of no return oil . Particularly long cold storage refrigeration piping system, ice-making system and flooded the low temperature freeze-drying equipment, ten minutes after boot or even tens of minutes did not return very little fuel oil or return to the situation is not unusual, the design The system will not occur while the compressor low oil pressure shutdown problem. The installation of high efficiency cooling system can greatly extend the oil separator back to the oil-free compressor operation time, after the compressor start to ride back to the oilphase of the crisis-free.Separated from the oil will not enter the system, with the flow of refrigerant in the tube, the formation of the oil cycle. Lubricating oil into the evaporator, the temperature is low because of low solubility on the one hand, part of the oil separated from the refrigerant; the other hand, low temperature viscosity, separated from the oil easily attached to the pipe wall, flow is more difficult . Evaporating temperature is lower, back to the oil more difficult. This requires the evaporation of pipeline design and pipe way back to the design and construction must be conducive to return to the oil, a common practice is to use down-style pipeline design, and to ensure a larger flow rate. For particularly low temperature refrigeration systems, such as -85 ° C and -150 ° C cold chamber for medical, in addition to selection of efficient oil separator, but usually add special solvent to prevent blocking capillaries and expansion valve oil, and help return oil.Practice, the evaporator and back to the trachea caused by improper road design back to the oil problem is not rare. For the R22 and R404A systems, flooded evaporator back to the oil is very difficult to design the system return lines must be very careful. For such systems, the use of highly efficient oil pipeline can greatly reduce the amount of oil into the system, effectively extending the boot back to the pipe back to the oil-free time.When the compressor than the location of the evaporator is high, the vertical back to back on the oil pipe bending is required. Return bends to compact as much as possible to reduce the storage of oil. The spacing between the oil return to the right bend, bend back the amount of oil relatively long time, should add some oil.Load the system return lines must also be careful. When the load is reduced, the back will reduce the gas velocity, the speed is too low is not conducive to return oil. In order to ensure oil return under low load, the vertical double suction riser pipe can be used. Compressor oil return is not conducive to frequent starts. Continuous operation time is very short because the compressor stopped, and returned too late to form a stable tracheal high-speed air flow, oil can only stay in the pipeline. Return less than Ben oil, compressor will be short of oil. The shorter operation time, longer pipelines, more complex systems, back to the oil problem is more prominent. For the safety switch is not closed hydraulic compressor (including the scroll compressor and rotary compressor) and some semi-hermetic compressors), damage caused by frequent starting is more and more. Compressor maintenance is equally important. Defrost when the evaporator temperature increases, the oil viscosity decreases, easy flow. After the defrost cycle, refrigerant velocity, the oil will stay focused on return to the compressor. Therefore, the defrost cycle of the frequency and duration of each also need to be carefully set to avoid large fluctuations in oil or oil strike.Back when the refrigerant gas leakage of more speed will decrease, the speed is too low will cause oil pipe stuck in the back way, you can not quickly return to the compressor. Within the shell back to the compressor oil does not mean back to the crankcase. Crank chamber with the principle of negative pressure compressor oil return, if the piston due to wear caused by leaks, crankcase pressure rise, oil return check valve automatically closes the role of pressure difference, from the return pipe to return the oil to remain in motor chamber, unable to enter the crankcase, which is the return to the oil issue, the return of oil starvation will cause the same problem. In addition to wear such an incident。

毕业论文外文翻译化学工业

《化学工程与工艺专业英语》中英文翻译

Unit 1 Chemical Industry化学工业1.Origins of the Chemical IndustryAlthough the use of chemicals dates back to the ancient civilizations, the evolution of what we know as the modern chemical industry started much more recently. It may be considered to have begun during the Industrial Revolution, about 1800, and developed to provide chemicals roe use by other industries. Examples are alkali for soapmaking, bleaching powder for cotton, and silica and sodium carbonate for glassmaking. It will be noted that these are all inorganic chemicals. The organic chemicals industry started in the 1860s with the exploitation of William Henry Perkin’s discovery if the first synthetic dyestuff—mauve. At the start of the twentieth century the emphasis on research on the applied aspects of chemistry in Germany had paid off handsomely, and by 1914 had resulted in the German chemical industry having 75% of the world market in chemicals. This was based on the discovery of new dyestuffs plus the development of both the contact process for sulphuric acid and the Haber process for ammonia. The later required a major technological breakthrough that of being able to carry out chemical reactions under conditions of very high pressure for the first time. The experience gained with this was to stand Germany in good stead, particularly with the rapidly increased demand for nitrogen-based compounds (ammonium salts for fertilizers and nitric acid for explosives manufacture) with the outbreak of world warⅠin 1914. This initiated profound changes which continued during the inter-war years (1918-1939).1．化学工业的起源尽管化学品的使用可以追溯到古代文明时代，我们所谓的现代化学工业的发展却是非常近代（才开始的）。

化学工业英语

化学工业英语The chemical industry is a cornerstone of modern society, transforming raw materials into essential products that enhance our daily lives.From the synthesis of pharmaceuticals to the productionof plastics, the chemical industry plays a vital role in innovation and development. Its impact is felt across various sectors, including healthcare, agriculture, and manufacturing.However, this industry also presents environmental challenges. The need for sustainable practices is paramount,as the chemical industry must balance progress with the preservation of our planet.Education in chemical engineering is crucial for the next generation of scientists and engineers. It equips them withthe knowledge to create safer and more efficient processes, ensuring a cleaner and more sustainable future.Research and development in the chemical industry are ongoing, with a focus on new materials and energy sources.This continuous pursuit of knowledge is what drives the industry forward and shapes the world we live in.The global nature of the chemical industry means that collaboration is key. International partnerships foster the exchange of ideas and technologies, leading to breakthroughsthat benefit all of humanity.Safety is a fundamental aspect of the chemical industry. Strict regulations and protocols are in place to protect workers and the public from potential hazards.In conclusion, the chemical industry is a dynamic field that offers both opportunities and responsibilities. Its contributions to society are significant, but it also requires a commitment to ethical and sustainable practices.。

化工英文文献译.

Three Common Details of The Compressor Failure AnalysisCompressor Fault Analysis (1) - motor burnedMotor compressor (hereinafter referred to as the compressor) of the fault can be divided into motor failure and mechanical failure (including the crankshaft, connecting rod, piston, valve, cylinder head pad, etc.). Mechanical failure is often the motor overload or stall, is one of the main motor damage.Damage mainly to the motor stator winding insulation damage (short circuit) and the circuit and so on.Stator windire changes. Frequent starts and abnormal load, so that the test winding subjected to high temperature will reduce the magnet wire insulation.In addition, the compressed gas with the compression ratio will be required to increase the load and pressure increases. Therefore, the high temperature compressor for low temperature, or low compressor for high temperature, will affect the electrical load and heat, is not appropriate, will shorten the electrode life.WindingNeed to draw particular attention to the two-stage compressor. In the two-stage compressor, back to the normal gas and oil directly back into the first grade (low grade) cylinder, compressed by the pressure of the cooling tube into the mectrical short circuit caused by metal shavings.Unfortunately, things tend to conspire a piece of the compressor in the boot of a problem when the news channels is often the oil burning. Severe wear of metal surfaces when the temperature is very high, while oil above 175 º C at the start of coking. System, if there is more moisture (vacuum pits not ideal, big oil and refrigerant water, negative pressure air into the return pipe burst, etc.), lubricants acid may occur. Acidic oil will corrode copper and winding insulation layer, on the one hand, it can cause copper plating phenomenon; on the other hand, this acid containing copper atoms very poor insulation properties of lubricating oil, provided the conditions for the winding circuit.3. Contactor problemContacts is an impo temperature in the lowest 80% of nameplate voltage can be closed.• When using a single contactor, the contactor must be greater than the motor nameplate rated current rating (RLA). Meanwhile, the contactor must be able to withstand motor stall current. If there are other loads downstream of the contactor, such as electrical fans, and so must also be considered.• When using two contactors, each contactor rating of the sub-winding stall must be equal to or greater than the rating of the compressor stall half-winding.Contacts can not be less than the rated current of the compressor nameplate rated current. Size small or poor quality of contact can not withstand the compressor starts, stall, and low voltage high current impact, single-phase or multiphase prone to contact bounce, the phenomenon of welding or even fall off, causing electrical damage.Contact jitter frequently start and stop the motor contactor. Frequent motor starts, a huge starting current and heat, will aggravate the winding insulation aging. Each time you start, the magnetic torque to the motor windings have small mobile and mutual friction. If there are other factors with (such as metal shavings, poor insulation oil, etc.) can easily lead to short circuits between windings. Thermal protection system is not designed to prevent such damage. In addition, the jitter of the contactor coil easy to failure. If you have contact with the coil is damaged, prone to single-phase state.If the small selection of the contactor, the contact arc, and can not afford to open due to the frequent instability of circulatory arrest or heat generated by the voltage control loop may be welded together or from the contact frame in the loss. Welding of the contacts will have a permanent single-phase state, theoverload protection device continuously cycle on and off.Needs to be stressed is that after the welding contactor, disconnect the compressor contactor power dependence of all the control loop (such as high and low pressure control, hydraulic control, defrost control, etc.) will all fail, the compressor is unprotected state.Therefore, when the motor burned, check the contacts are essential processes. Contacts lead to motor damage is often forgotten as a major reason.Compressor Fault Analysis (2) - liquid strike1. Processes and phenomena(1) suction valves are breakingCompressed gas compressor is a machine. Typically, compressed air piston 1450 times per minute (half-closed compressor), or 2900 times (all closed compressor), a suction or exhaust to complete the process time is 0.02 seconds or less. Suction and discharge valve plate of the size of the aperture and the suction valve sheet flexibility and strength are designed in accordance with the gas flow. The force from the perspective of the valve, the gas flow impact force is relatively uniform.The density of the liquid is dozens or even hundreds of times the gas, and thus the momentum of the liquid flow much larger than the gas, the impact force is also much larger. Mixed with more droplets aspirated into the cylinder when the flow is two-phase flow. Two-phase flow in the suction valve chip is not only the impact of high intensity and frequency, as if the typhoon beat mixed with pebbles at the window, the destructive self-evident. Is the liquid suction valve are breaking hit one of the typical characteristics and processes.(2) rod fractureCompression stroke of the time about 0.02 seconds, while the discharge process will be more short-lived. Or liquid droplets in the cylinder must be in such a short period of time discharged from the vent, the speed and momentum is significant. The case of exhaust valve and the suction valve sheet film the same, the difference is limited piece exhaust valve plate and spring-bit support is not easy to break. The impact of serious, limit deformation plate will tilt.If the liquid does not evaporate and discharge time cylinder, piston near top dead center when the compressed liquid, due to a very short time, the compressed liquid the process seems to be hit, also came in the metal cylinder head knocking. Compressed liquid is a liquid hammer or another part of the process.Instantly generate high-pressure liquid hit the broken ring of the great, the beginning of the familiar rod bending or breaking, the other pieces of compression force (valve plate, disc pads, crankshaft, piston, piston pin, etc.) will also be deformed or damage, but often overlooked, or confused with the exhaust pressure is too high. Maintenance of the compressor, people will be very easy to find bent or broken connecting rod, and give replacement, and forget to check whether there are other parts of deformed or damaged, thus laying the seeds for future failure.Attack caused by the fracture fluid is different from the axle rod and piston cylinder bite, it can tell. First, the liquid hit causing rod bent or broken in the short span of time, the rod ends of the piston and crankshaft motion freely, and not generally cause serious wear and tear or bite cylinder axle. Despite the broken piece suction valve, the valve can cause debris occasionally serious scratch piston and cylinder surface, but scratch the surface caused by wear and lubrication failure is very different. Secondly, the liquid caused by rod fracture attack is caused by stress, the connecting rod and a compression feature offstubble. Although the bite cylinder piston rod after the squeeze is also likely to fracture, but only to be stuck in the cylinder piston. Link broken axle after more different, connecting rod and crankshaft are badly scratched, resulting in a broken force is shear stress, are not the same broken stubble. Finally, and bite-cylinder front axle, the motor overload, severe motor heating, thermal protection will be action.2. ReasonsObviously, the compressor can cause the liquid fluid is nothing more than hit several sources as follows: 1) back to the fluid, which flows back to the compressor from the evaporator liquid refrigerant or lubricating oil; 2) starts with a liquid foam; 3) compressor lubricant too much. This paper will analyze each of these types of reasons.(1) back to the liquidTypically, back to the compressor run-time solution is the evaporator liquid refrigerant in the suction line back to the compressor through the phenomenon or process.For the refrigeration system expansion valve, expansion valve back to liquid and is closely related to improper selection and use. Expansion valve selection is too large, too small to set superheat, temperature of installation method is not correct or damaged insulation wrap, expansion valve failure can cause back to the fluid. For a small refrigeration system using capillary, the increase will cause excessive fluid back to liquid.Hot gas defrost system using prone to back solution. Regardless of the heat pump reversing valve operation, or by cooling hot gas bypass valve operation, hot gas defrost the evaporator after the formation of large amounts of liquid, the liquid refrigerant in the subsequent start of the run both possible and return to the compressor.In addition, severe frost evaporator fan failure or deterioration of heat transfer, no evaporation will cause the liquid back to liquid. Cold storage temperature fluctuations can also cause frequent reaction failures caused by the expansion valve back to liquid.Back to the liquid medium caused the accident hit mostly in air-cooled type (referred to as air-cooled or air cooled) semi-hermetic compressors and single two-stage compressors, compressor cylinders because they are directly connected with the return pipe, and once back to the fluid, easily lead to fluid strike accidents. Even if the strike did not cause fluid to return fluid into the cylinder will be diluted or washed away the wall of the piston and cylinder lubricating oil, increased piston wear.For the return air (refrigerant vapor) cooled semi-closed and closed compressor, back to the liquid rarely cause fluid attack. But it will dilute the crankcase oil. Contains large amounts of liquid refrigerant in the oil viscosity is low, the friction surface can not form a sufficient oil film, resulting in rapid wear of moving parts. In addition, the refrigerant oil in the transport process in the case of boiling heat will affect the normal transport lubricants. The farther from the pump, the more obvious the more serious problems. If a serious motor side bearing wear, the crankshaft to the side of the settlement could easily lead to the stator and the motor burned sweep Church.Obviously, back to the liquid solution will not only lead to strike, but also the wear of lubricating oil dilution. Wear and current load the motor will be greatly increased, over time will cause motor failure.Difficult to avoid the return liquid cooling system, installation of gas-liquid separator and taking the time to stop using the control can prevent or reduce the harm back to liquid.(2) start with liquidReturn air-cooled compressor is started, the crankcase oil is called the phenomenon of severe blistering start with liquid. When starting with a blistering fluid in the oil sight glass can be clearly observed. Start with the root cause of liquid dissolved in oil and submerged in the oil following a large number of therefrigerant, the pressure suddenly decreases suddenly boiling and cause blistering oil. This phenomenon is similar to our daily lives and suddenly open the coke cola bottle bubble phenomenon. The length of the duration of foaming agent into the area and cooling, usually a few minutes or ten minutes. The surface of a large number of bubbles floating in the oil, and even filled the crankcase. Once the cylinder through the suction inlet, the bubble will be reduced to liquid (a mixture of oil and refrigerant) can easily lead to fluid attack. Obviously, start with a liquid solution due to hit only occurs during the startup process.And back to the liquid is different from cause to start with liquid refrigerant is "refrigerant migration" of the way into the crankcase. Refrigerant migration is the compressor stops running, the evaporator refrigerant in gaseous form, through the trachea way back into the oil absorbed by the compressor or condensing in the compressor oil after mixing with the process or phenomenon.After the compressor is stopped, the temperature will decrease, and the pressure will rise. As the refrigerant vapor lubricant points down, it will absorb the oil surface of the refrigerant vapor, causing crankcase pressure lower than the evaporator pressure phenomenon. Lower oil temperature, the lower the vapor pressure of refrigerant vapor in the greater absorption of force. Evaporator to the crankcase vapor will slowly "migrate." In addition, if the compressor outside, cold weather or at night, the temperature is often lower than the indoor evaporator, the crankcase pressure there is low, the refrigerant can easily migrate to the compressor and into oil by condensation.Refrigerant migration is a very slow process. The longer the compressor is stopped, migrated to the oil in the refrigerant with it. Exist as long as the evaporator liquid refrigerant, this process will be conducted. As the refrigerant dissolved heavy oil, it will sink to the bottom of the crankcase, and oil floating in the above can also absorb more refrigerant.In addition to outside attack likely to cause liquid refrigerant migration will dilute the lubricating oil. Is very dilute oil pump to the friction surface, rinse out the original film may be washed, causing severe wear (a phenomenon often called refrigerant erosion). Wear transition with the gap will become larger, causing oil spills, thus affecting distant parts of the lubrication oil pressure will cause serious protection action.Due to structural reasons, the air-cooled compressor starts reducing crankcase pressure will be much slower, not very severe blistering, the bubble is difficult to enter the cylinder, air-cooled compressor so there is no problem with liquid starting fluid attack.In theory, the compressor crankcase heater installed (electric heater) can effectively prevent refrigerant migration. Short stop (eg at night), the crankcase heater to maintain power, the system can make the oil temperature is higher than other parts, refrigerant migration does not occur. No downtime (such as a winter), the heating oil before you start a few or ten hours, to evaporate the majority of oil in the refrigerant fluid can either start with a greatly reduced possibility of liquid strike , which also can reduce the harm caused by erosion of refrigerant. However, the actual application, the heater power to maintain after the shutdown or give ten hours before the heater power supply is difficult. Therefore, the practical effect of the crankcase heater will be greatly reduced.For larger systems, shut down before the evaporator to the compressor pumping liquid refrigerant (known as taking the time to stop), can fundamentally prevent refrigerant migration. The pipe on the way back to the installation of gas-liquid separator, refrigerant migration can increase the resistance and reduce migration.Of course, by improving the compressor structure, can prevent refrigerant migration and reduce oil foaming degree. By improving the return-air-cooled compressor oil return path in the motor crankcase cavity and increased channel migration points (back pumps, etc.), you can cut off the access road after the shutdown, the refrigerant can not enter the crankshaft chamber; reduced intake Road and cross thechannel to the crankcase when the crankcase pressure to slow down the boot speed, then control the degree of foaming and foam into the cylinder volume.(3) too much oilSemi-hermetic compressors usually have the oil sight glass to observe the oil level. Oil sight glass oil level above the range, indicating that the oil too much. Oil level is too high, high-speed rotation of the crankshaft and connecting rod may hit oil level frequently, causing a lot of splash oil. Once the oil splash fleeing into the inlet, into the cylinder, causing fluid to be hit.Large refrigeration system installation, they often need to add the appropriate lubricant. But for the poor oil return system, to seriously affect oil return to find the root causes of, and blindly added oil is dangerous. Even if the oil level being low, but also pay attention to sudden and large returns lubricating oil (such as after defrost) may cause danger. Attack caused by liquid lubricants are not uncommon.Compressor Failure Analysis (3) - lack of lubrication and lack of lubrication1. Lack of oilLack of oil is very easy to identify one of the compressor failure, compressor short of oil in the crankcase oil when little or no oil.Compressor is a special pump, a large number of refrigerant gas being discharged from the folder and also take a small portion of oil (known as Ben oil or an oil spill.) Ben compressor oil is inevitable, but Ben is different oils speed. Semi-sealed piston compressor discharge in about 2-3% of the oil, while the scroll compressor is 0.5-1%. For a displacement 100m3/hr, crankcase oil storage capacity of 6 liters of 6-cylinder compressor, 3% of the rush of oil means that about 0.3-0.8 liters / minute Ben oil, or running back to the oil-free compressor time for ten minutes.Discharge of the compressor oil does not return, the compressor will be short of oil. Compressor oil return in two ways, one is the oil separator oil return, the other is the return pipe back to the oil. Oil separator installed in the compressor discharge pipe on the road, generally isolated from 50-95% of the Ben oil, back to better effect, fast, greatly reducing the amount of oil into the system piping, which effectively extended the running time of no return oil . Particularly long cold storage refrigeration piping system, ice-making system and flooded the low temperature freeze-drying equipment, ten minutes after boot or even tens of minutes did not return very little fuel oil or return to the situation is not unusual, the design The system will not occur while the compressor low oil pressure shutdown problem. The installation of high efficiency cooling system can greatly extend the oil separator back to the oil-free compressor operation time, after the compressor start to ride back to the oil phase of the crisis-free. Separated from the oil will not enter the system, with the flow of refrigerant in the tube, the formation of the oil cycle. Lubricating oil into the evaporator, the temperature is low because of low solubility on the one hand, part of the oil separated from the refrigerant; the other hand, low temperature viscosity, separated from the oil easily attached to the pipe wall, flow is more difficult . Evaporating temperature is lower, back to the oil more difficult. This requires the evaporation of pipeline design and pipe way back to the design and construction must be conducive to return to the oil, a common practice is to use down-style pipeline design, and to ensure a larger flow rate. For particularly low temperature refrigeration systems, such as -85 ° C and -150 ° C cold chamber for medical, in addition to selection of efficient oil separator, but usually add special solvent to prevent blocking capillaries and expansion valve oil, and help return oil.Practice, the evaporator and back to the trachea caused by improper road design back to the oil problem is not rare. For the R22 and R404A systems, flooded evaporator back to the oil is very difficult to designthe system return lines must be very careful. For such systems, the use of highly efficient oil pipeline can greatly reduce the amount of oil into the system, effectively extending the boot back to the pipe back to the oil-free time.When the compressor than the location of the evaporator is high, the vertical back to back on the oil pipe bending is required. Return bends to compact as much as possible to reduce the storage of oil. The spacing between the oil return to the right bend, bend back the amount of oil relatively long time, should add some oil.Load the system return lines must also be careful. When the load is reduced, the back will reduce the gas velocity, the speed is too low is not conducive to return oil. In order to ensure oil return under low load, the vertical double suction riser pipe can be used.Compressor oil return is not conducive to frequent starts. Continuous operation time is very short because the compressor stopped, and returned too late to form a stable tracheal high-speed air flow, oil can only stay in the pipeline. Return less than Ben oil, compressor will be short of oil. The shorter operation time, longer pipelines, more complex systems, back to the oil problem is more prominent. For the safety switch is not closed hydraulic compressor (including the scroll compressor and rotary compressor) and some semi-hermetic compressors), damage caused by frequent starting is more and more.Compressor maintenance is equally important. Defrost when the evaporator temperature increases, the oil viscosity decreases, easy flow. After the defrost cycle, refrigerant velocity, the oil will stay focused on return to the compressor. Therefore, the defrost cycle of the frequency and duration of each also need to be carefully set to avoid large fluctuations in oil or oil strike.Back when the refrigerant gas leakage of more speed will decrease, the speed is too low will cause oil pipe stuck in the back way, you can not quickly return to the compressor.Within the shell back to the compressor oil does not mean back to the crankcase. Crank chamber with the principle of negative pressure compressor oil return, if the piston due to wear caused by leaks, crankcase pressure rise, oil return check valve automatically closes the role of pressure difference, from the return pipe to return the oil to remain in motor chamber, unable to enter the crankcase, which is the return to the oil issue, the return of oil starvation will cause the same problem. In addition to wear such an incident occurred in the old machine, refrigerant migration triggered by starting with a liquid can also cause problems within the oil return, but usually shorter, up to ten minutes.The problem occurs when the oil return, the compressor oil level can be observed declining until the oil pressure safety device action. After the compressor is stopped, the crankcase oil level soon resume. Root of the problem back to the oil within the cylinder is leaking, it is timely replacement of worn piston assembly.Hydraulic safety protection device will automatically stop short of oil, protect the compressor from damage. Not as the mirror and hydraulic oil closed compressor safety devices (including the rotor and the scroll compressor) and the air compressor, starvation without obvious symptoms, it will not shut down the compressor damaged unknowingly wear . Compressor noise, vibration or current is too large, may be short of oil on the compressor and system operation to determine the exact status of it is very important. Ambient temperature is too low may result in some hydraulic safety device failure will cause the compressor wear.Compressor wear and tear caused by lack of oil is generally more uniform. If little or no oil lubrication, the bearing surface there will be intense friction, the temperature will rise rapidly in a few seconds. If electrical power is large enough, will continue to rotate the crankshaft, the crankshaft and the bearingsurface is worn or scratched, or will be bearing crankshaft locking, stop turning. Reciprocating piston within the cylinder is the same movement, lack of lubrication can cause wear or scratch card in severe piston inside the cylinder will not exercise.2. Insufficient lubricationThe immediate cause of wear and tear insufficient lubrication. Lack of oil will surely lead to lack of lubrication, but oil lubrication is not necessarily a lack of oil caused by lack of. The following three reasons can also cause lack of lubrication: oil can not reach the bearing surface; lubricants Although arrive bearing surface, but the viscosity is too small to form a film of adequate thickness; Although oil to reach the bearing surface, but due to overheating broken down, and can not play lubrication.压缩机常见三种详细故障分析压缩机常见故障分析(1)——电机烧毁电动机压缩机（以下简称压缩机）的故障可分为电机故障和机械故障(包括曲轴，连杆，活塞，阀片，缸盖垫等)。

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XXXX大学本科毕业设计(论文)外文翻译原文：Chemical Industry1.Origins of the Chemical IndustryAlthough the use of chemicals dates back to the ancient civilizations, the evolution of what we know as the modern chemical industry started much more recently. It may be considered to have begun during the Industrial Revolution, about 1800, and developed to provide chemicals roe use by other industries. Examples are alkali for soapmaking, bleaching powder for cotton, and silica and sodium carbonate for glassmaking. It will be noted that these are all inorganic chemicals. The organic chemicals industry started in the 1860s with the exploitation of William Henry Perkin’s discovery if the first synthetic dyestuff—mauve. At the start of the twentieth century the emphasis on research on the applied aspects of chemistry in Germany had paid off handsomely, and by 1914 had resulted in the German chemical industry having 75% of the world market in chemicals. This was based on the discovery of new dyestuffs plus the development of both the contact process for sulphuric acid and the Haber process for ammonia. The later required a major technological breakthrough that of being able to carry out chemical reactions under conditions of very high pressure for the first time. The experience gained with this was to stand Germany in good stead, particularly with the rapidly increased demand for nitrogen-based compounds (ammonium salts for fertilizers and nitric acid for explosives manufacture) with the outbreak of world warⅠin 1914. This initiated profound changes which continued during the inter-war years (1918-1939).Since 1940 the chemical industry has grown at a remarkable rate, although this has slowed significantly in recent years. The lion’s share of this growth has been in the organic chemicals sector due to the development and growth of the petrochemicals area since 1950s. The explosives growth in petrochemicals in the 1960s and 1970s was largely due to the enormous increase in demand for synthetic polymers such as polyethylene, polypropylene, nylon, polyesters and epoxy resins.The chemical industry today is a very diverse sector of manufacturing industry, within which it plays a central role. It makes thousands of different chemicals which the general public only usually encounter as end or consumer products. These products are purchased because they have the required properties which make them suitable for some particular application, e.g. a non-stick coating for pans or a weedkiller. Thus chemicals are ultimately sold for the effects that they produce.2. Definition of the Chemical IndustryAt the turn of the century there would have been little difficulty in defining what constituted the chemical industry since only a very limited range of products was manufactured and these were clearly chemicals, e.g., alkali, sulphuric acid. At present, however, many intermediates to productsproduced, from raw materials like crude oil through (in some cases) many intermediates to products which may be used directly as consumer goods, or readily converted into them. The difficulty cones in deciding at which point in this sequence the particular operation ceases to be part of the chemical industry’s sphere of activities. To consider a specific example to illustrate this dilemma, emulsion paints may contain poly (vinyl chloride) / poly (vinyl acetate). Clearly, synthesis of vinyl chloride (or acetate) and its polymerization are chemical activities. However, if formulation and mixing of the paint, including the polymer, is carried out by a branch of the multinational chemical company which manufactured the ingredients, is this still part of the chemical industry of does it mow belong in the decorating industry?It is therefore apparent that, because of its diversity of operations and close links in many areas with other industries, there is no simple definition of the chemical industry. Instead each official body which collects and publishes statistics on manufacturing industry will have its definition as to which operations are classified as the chemical industry. It is important to bear this in mind when comparing statistical information which is derived from several sources.3. The Need for Chemical IndustryThe chemical industry is concerned with converting raw materials, such as crude oil, firstly into chemical intermediates and then into a tremendous variety of other chemicals. These are then used to produce consumer products, which make our lives more comfortable or, in some cases such as pharmaceutical produces, help to maintain our well-being or even life itself. At each stage of these operations value is added to the produce and provided this added exceeds the raw material plus processing costs then a profit will be made on the operation. It is the aim of chemical industry to achieve this.It may seem strange in textbook this on e to pose the question ―do we need a chemical industry?‖ However trying to answer this question will provide(ⅰ) an indication of the range of the chemical industry’s activities, (ⅱ) its influence on our lives in everyday terms, and (ⅲ) how great is society’s need for a chemical industry. Our approach in answering the question will be to consider the industry’s co ntribution to meeting and satisfying our major needs. What are these? Clearly food (and drink) and health are paramount. Other which we shall consider in their turn are clothing and (briefly) shelter, leisure and transport.(1)Food. The chemical industry makes a major contribution to food production in at least three ways. Firstly, by making available large quantities of artificial fertilizers which are used to replace the elements (mainly nitrogen, phosphorus and potassium) which are removed as nutrients by the growing crops during modern intensive farming. Secondly, by manufacturing crop protection chemicals, i.e., pesticides, which markedly reduce the proportion of the crops consumed by pests. Thirdly, byproducing veterinary products which protect livestock from disease or cure their infections.(2)Health. We are all aware of the major contribution which the pharmaceutical sector of the industry has made to help keep us all healthy, e.g. by curing bacterial infections with antibiotics, and even extending life itself, e.g. ß–blockers to lower blood pressure.(3)Clothing. The improvement in properties of modern synthetic fibers over the traditional clothing materials (e.g. cotton and wool) has been quite remarkable. Thus shirts, dresses and suits made from polyesters like Terylene and polyamides like Nylon are crease-resistant, machine-washable, and drip-dry or non-iron. They are also cheaper than natural materials.Parallel developments in the discovery of modern synthetic dyes and the technology to ―bond‖ th em to the fiber has resulted in a tremendous increase in the variety of colors available to the fashion designer. Indeed they now span almost every color and hue of the visible spectrum. Indeed if a suitable shade is not available, structural modification of an existing dye to achieve this can readily be carried out, provided there is a satisfactory market for the product. Other major advances in this sphere have been in color-fastness,i.e., resistance to the dye being washed out when the garment is cleaned.(4)Shelter, leisure and transport. In terms of shelter the contribution of modern synthetic polymers has been substantial. Plastics are tending to replace traditional building materials like wood because they are lighter, maintenance-free (i.e. they are resistant to weathering and do not need painting). Other polymers, e.g. urea-formaldehyde and polyurethanes, are important insulating materials f or reducing heat losses and hence reducing energy usage.Plastics and polymers have made a considerable impact on leisure activities with applications ranging from all-weather artificial surfaces for athletic tracks, football pitches and tennis courts to nylon strings for racquets and items like golf balls and footballs made entirely from synthetic materials.Likewise the chemical industry’s contribution to transport over the years has led to major improvements. Thus development of improved additives like anti-oxidants and viscosity index improves for engine oil has enabled routine servicing intervals to increase from 3000 to 6000 to 12000 miles. Research and development work has also resulted in improved lubricating oils and greases, and better brake fluids. Yet again the contribution of polymers and plastics has been very striking with the proportion of the total automobile derived from these materials—dashboard, steering wheel, seat padding and covering etc.—now exceeding 40%.So it is quite apparent even from a brief look at the chemical industry’s contribution to meeting our major needs that life in the world would be very different without the products of the industry. Indeed the level of a country’s development may be judged by the production level and sophistication of its chemical industry4. Research and Development (R&D) in Chemical IndustriesOne of the main reasons for the rapid growth of the chemical industry in the developed world has been its great commitment to, and investment in research and development (R&D). A typical figure is 5% of sales income, with this figure being almost doubled for the most research intensive sector, pharmaceuticals. It is important to emphasize that we are quoting percentages here not of profits but of sales income, i.e. the total money received, which has to pay for raw materials, overheads, staff salaries, etc. as well. In the past this tremendous investment has paid off well, leading to many useful and valuable products being introduced to the market. Examples include synthetic polymers like nylons and polyesters, and drugs and pesticides. Although the number of new products introduced to the market has declined significantly in recent years, and in times of recession the research department is usually one of the first to suffer cutbacks, the commitment to R&D remains at a very high level.The chemical industry is a very high technology industry which takes full advantage of the latest advances in electronics and engineering. Computers are very widely used for all sorts of applications, from automatic control of chemical plants, to molecular modeling of structures of new compounds, to the control of analytical instruments in the laboratory.Individual manufacturing plants have capacities ranging from just a few tones per year in the fine chemicals area to the real giants in the fertilizer and petrochemical sectors which range up to 500,000 tonnes. The latter requires enormous capital investment, since a single plant of this size can now cost $520 million! This, coupled with the widespread use of automatic control equipment, helps to explain why the chemical industry is capital-rather than labor-intensive.The major chemical companies are truly multinational and operate their sales and marketing activities in most of the countries of the world, and they also have manufacturing units in a number of countries. This international outlook for operations, or globalization, is a growing trend within the chemical industry, with companies expanding their activities either by erecting manufacturing units in other countries or by taking over companies which are already operating there.。

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