atmospheric distillation

atmospheric distillation检索关键词：atmospheric distillation检索步骤：进入Elsevier 点击Search ,进入All Sources检索界面，在搜索框中输入：atmospheric distillation，Source中选择All Sources，Subject中选择Chemical Engineering，Data Range中选择All Years。

点击搜索检索结果：共6822篇结果检索结论：First：The use of this residual heat reduces the furnace duty by approximately an equivalent amount. Thus high level energy (fuel-gas burnt in the furnace) is replaced by residual low level heat. The simulation with an example flowsheet shows that the savings on fuel could be as high as 21%.Second：The purpose of this paper is to describe a specific application of energy integration improvement achieved by modifying the flowsheet of the crude oil atmosphericdistillation process. It differs from other methods by the application of exergy analysis to visualize and better understand the distribution of energy degradations in thedistillation column in order to find a suitable solution to reduce them.A close look at this distribution for a simple model process shows the unnecessary presence of light species throughout the whole column, whereas they could be separated before being fed to the furnace and sent directly to the upper part of the column. Since the crude oil is continuously vaporized, the installation of flashes in the preheating train ensures this separation, avoids the unnecessary overheating of the vaporized species and offers a considerable potential in reduction of fuel consumption in the furnace. However, this potential reduction is obtained under a simplification that needs to be revisited in the framework of a more realistic and more complex flowsheet. This will be done in the second pa rt, of which this first part sets the backgroundThird：A distillation column operating under pressurized conditions may not be designed for full vacuum. A vacuum relief valve on such column must, therefore, be sized to prevent negative pressures in the shell under the worst case scenario, i.e. when the feed, bottoms, distillate and reboiler steam are cut off, but the condenser still operates. The valve can be sized considering that the inflowing air (or other gas) first accumulates in the condenser, which is the vacuum source, and blankets the heat exchange area stopping the condensation.A conservative estimate of the amount of air required to blanket the condenser is given by the condenser volume. The rate at which this inflow must occur can be found from a transient total energy balance around the column, as described below. This method has been applied for valve sizing in real columns and results in reasonable valve sizes. To the best of our knowledge, no other method for carrying out this calculation is available in the open literature. Forth：Conventional vacuum relief methodologies are usually protective responses; that is,they accomplish their purpose by substitution of an inert gas (usually nitrogen) for the process gases removed by an external vacuum source, or for condensable vapour collapsed by an internal process mechanism (e.g. condensation). While this approach is theoretically possible for all potential vacuum scenarios, it becomes practically impossible to implement for installations where a rapid phase change can impart near-instantaneous system pressure reductions. The procedure outlined in this paper takes a preventive approach: eliminate the source of vacuum generation before the safe lower system pressure limit is reached. For distillation and other refluxing systems, this vacuum source is usually the main overhead condenser, which is designed to collapse large volumes of condensable vapour. To eliminate the vacuum source requires elimination of the system's ability to rapidly condense vapour. This goal is accomplished by introduction of inert gas directly into the condensing system to ‘blanket’ the heat transfer surface and stop condensation. The procedure determines the rate, amount and location for introduction of inert gas. The required design data include: (i) system starting pressure, (ii) maximum allowable system vacuum, (iii) volume of the condensing system, and (iv) normal system condensing rate. By determining the rate at which the condenser removes vapour volume from the system, and designing an inert gas delivery system to meet or exceed this rate, the vacuum generation potential of the system is effectively eliminated using a much smaller quantity of inert gas than with the more traditional volume substitution methods.。