生物质 水热煤化工艺
水热碳化——精选推荐
⽔热碳化定义：⽔热碳化以⽣物质为原料,⽔作为液相反应介质,在⼀定温度(150-250℃)和压⼒(2-10 MPa)下,将⽣物质转化为以⽣物炭为主的⼀系列⾼附加值产物。
⽔热碳化是⼀种⾼效的废弃⽣物质资源化技术。
⽔热碳化是指将⽣物质废弃物置于⾼温(150-350℃)⽔溶液中停留⼀段时间,脱⽔脱羧形成具有明确理化性质的固体产物。
⽔热碳化是将⽣物质转化为更⾼能量密度形式的碳的⼀种有效途径,也是制备⽣物质炭材料和⽣物油的重要⽅法。
⽔热碳化温度、时间：本⽂采⽤废弃⽣物质松⼦壳和⽟⽶芯作为原料,分别在不同的⽔热碳化温度(180℃、200℃、230℃)下反应5 h,利⽤扫描电⼦显微镜(SEM)、红外光谱分析(FT-IR)、元素分析、含氧官能团测定等⼿段对所得⽔热炭进⾏了详细的表征。
SEM显⽰当温度达到220℃时,碳化物表⾯开始形成微球结构,且随着温度和时间的增⼤,微球结构均⼀性、分散度越来越好。
在温度为200℃时,分别利⽤Fe3+、柠檬酸作为添加剂。
结果表明,Fe3+、柠檬酸均能促进⽣物质的⽔热碳化过程，所得⽔热炭的热值提⾼了20-40%，SEM显⽰，添加Fe3+的⽟⽶芯和松⼦壳⽔热炭表⾯⽣成的炭微球数量显著，且球形完整、粒径较⼤、表⾯光滑；添加柠檬酸的⽔热炭表⾯的炭微球粒径在纳⽶级别,呈现致密的蜂窝状。
在反应温度260℃、停留时间为1h时，⽣物炭能量密度已经提⾼了69.45%，获得了较⾼的能量密度，进⼀步提⾼反应剧烈程度能提升的能量密度有限。
扫描电镜分析说明经过⽔热碳化处理的⽣物炭整体呈现碎⽚状态，并伴有⼤量蜂窝状结构，可能是脱羰基反应导致稻草内部的纤维素、半纤维素⼤量分解。
在反应温度260℃,停留时间1h时，固相产物吸⽔率较低，故此条件下⽣物炭的性能良好，是制备⽣物炭的较适宜条件。
与⼲法碳化相⽐，⽔热碳化保留了较多的有机碳。
⼲法碳化后的污泥炭较原污泥呈现弱碱化，⽽⽔热碳化则显⽰酸化趋势。
此外,与⼲法碳化相⽐，⽔热碳化在富集有效营养元素(磷、氮)和固定重⾦属浸出风险上均表现出明显的优势。
生物质能源热分解的热力学分析及工艺优化
生物质能源热分解的热力学分析及工艺优化随着经济的发展和工业化程度的不断提高，能源供应的紧张和污染的不断加剧已经成为了全球性的问题。
而在这种情况下，生物质能所蕴含的清洁、可再生、广泛分布、快速更新等优点已经引起了越来越多人的关注。
生物质能源通过热分解可以得到大量的高品质气体、液体、固体能源，因此热分解技术是生物质利用的重要手段之一。
本文将对生物质能源热分解的热力学分析及工艺优化进行一定的探讨。
一、热分解过程及理论基础热分解是指生物质经过适当的加热后，原有的化学键断裂，生成一系列新的气体、液体和固体产品的过程。
热分解过程有许多因素会影响其生成物种类和产量，其中热力学因素就是其中的关键因素之一。
热力学分析是对物质转化过程中热特性的分析，一般可以通过广义的焓、熵和自由能三个参数来描述热特性。
在热分解过程中，热力学参数的变化将直接影响生物质的转化过程，因此对热力学变化的研究十分重要。
在热分解过程中，生物质中的纤维素和半纤维素被分解成一系列的小分子产品，如纤维素、葡萄糖、木糖、乙酸、乙醇等。
同时，也会生成大量的气体如甲烷、一氧化碳、二氧化碳等，固体产品主要是生物质的残渣和少量灰分。
二、热分解反应机理生物质经过适当的加热后，化学键断裂，生成一系列新的气体、液体和固体产品，这个过程涉及到多种热化学反应，如脱除水分、发生裂解、异构、复分解、气固反应等反应机制，因此生物质热分解的反应机理比较复杂。
从热力学角度上看，生物质经过加热后会发生反应，反应过程需要吸热。
随着反应的进行，温度逐渐升高，反应的吸热量也会逐渐变大。
而当吸热量达到最大值时，就可以得到最优的生物质利用效率。
三、热分解反应动力学热分解的反应动力学是指热分解反应速率随时间和温度的变化关系。
这个过程可以描述为一个复杂的反应动力学模型，最简单的是一级动力学反应模型。
从实验结果来看，生物质热分解的反应速率是随着温度的升高而加快的，且温度越高，反应速率的加快越明显。
水热反应+厌氧消化+机械脱水+干化
水热反应、厌氧消化、机械脱水与干化在生物质能源利用过程中起到了重要作用。
本文将从这四个方面进行详细介绍，希望能为相关领域的研究和实践提供一定的帮助。
一、水热反应水热反应是一种在高温高压水环境下进行的化学反应。
在生物质能源利用中，水热反应常用于生物质的裂解和转化。
通过加热生物质和水混合物，可使生物质中的纤维素、半纤维素和木质素等组分发生水解、糖化和裂解反应，生成可溶解的糖类、酚类和木质素衍生物，从而为后续的能源利用提供了原料。
水热反应也能使生物质中的结构得到改善，提高生物质的可降解性和可利用性。
二、厌氧消化厌氧消化是一种利用微生物代谢产生甲烷气体的生物化学反应。
在生物质能源利用中，厌氧消化常用于处理有机废弃物和农作物残余物。
通过将生物质原料放置于密封的消化罐中，与厌氧菌共同发酵产气，可生成高能甲烷气体，用于发电或供热。
厌氧消化还能有效降解生物质中的有害物质，减少环境污染，具有环保的双重效益。
三、机械脱水机械脱水是一种利用机械设备将生物质中的水分进行除去的处理方法。
在生物质能源利用中，机械脱水常用于处理厌氧消化后的污泥或生物质颗粒。
通过离心脱水、压榨脱水等方式，将生物质中的水分含量减少，可提高生物质颗粒的热值和稳定性，使之更方便于储存和运输。
机械脱水还能使厌氧消化后的污泥更易于处理和处置，减少对环境的影响。
四、干化干化是一种通过加热或通风等方式将生物质中的水分蒸发或挥发除去的过程。
在生物质能源利用中，干化常用于生物质燃料的生产和利用。
通过烘干、晾晒、风干等方式，可使生物质中的水分含量减少，提高燃烧效率和发热值，从而为生物质燃料的应用提供更好的条件。
干化还能延长生物质的保存期限，减少贮存中的霉菌和腐烂现象，提高生物质的品质和价值。
总结起来，水热反应、厌氧消化、机械脱水和干化是生物质能源利用过程中不可或缺的重要环节。
它们在裂解、转化、处理和利用生物质中发挥着重要作用，为生物质能源的开发和利用提供了有力支撑。
第十章 生物质热解技术
第十章生物质热解技术1 概述热化学转化技术包括燃烧、气化、热解以及直接液化，转化技术与产物的相互关系见图10-1。
热化学转化技术初级产物可以是某种形式的能量携带物，如，木炭（固态）、生物油（液态）或生物质燃气（气态），或者是能量。
这些产物可以被不同的实用技术所使用，也可通过附加过程将其转化为二次能源加以利用。
图10-1 热化学转化技术与产物的相互关系生物质热解、气化和直接液化技术都是以获得高品位的液体或者气体燃料以及化工制品为目的，由于生物质与煤炭具有相似性，它们最初来源于煤化工（包括煤的干馏、气化和液化）。
本章中主要围绕热解展开。
1.1生物质热解概念热解（Pyrolysis又称裂解或者热裂解）是指在隔绝空气或者通入少量空气的条件下，利用热能切断生物质大分子中的化学键，使之转变成为低分子物质的过程。
可用于热解的生物质的种类非常广泛，包括农业生产废弃物及农林产品加工业废弃物、薪柴和城市固体废物等。
关于热解最经典的定义源于斯坦福研究所的J. Jones提出的，他的热解定义为“在不向反应器内通入氧、水蒸气或加热的一氧化碳的条件下，通过间接加热使寒潭有机物发生热化学分解，生成燃料（气体、液体和固体）的过程”。
他认为通过部分燃烧热解产物来直接提供热解所需热量的情况，严格地讲不应该称为部分燃烧或缺氧燃烧。
他还提出将严格意义上的热解和部分燃烧或缺氧燃烧引起的气化、液化等热化学过程统称为PTGL（Pyrolysis，Thermal Gasification or Liquification）过程。
生物质由纤维素、半纤维素和木质素三种主要组分组成，纤维素是β-D-葡萄糖通过C1-C4苷键联结起来的链状高分子化合物，半纤维素是脱水糖基的聚合物，当温度高于500℃时，纤维素和半纤维素将挥发成气体并形成少量的炭。
木质素是具有芳香族特性的，非结晶性的，具有三度空间结构的高聚物。
由于木质素中的芳香族成分受热时分解较慢，因而主要形成炭。
生物质气化及生物质与煤共气化技术的研发与应用
生物质气化及生物质与煤共气化技术的研发与应用摘要：总结了生物质原料的特点及生物质单独气化的缺点；介绍了国内外生物质气化技术及生物质与煤共气化技术的研发与应用现状；分析了在此领域国内外的发展趋势与前景；概括了开展生物质与煤共气化技术研发的意义。
生物质包括植物、动物及其排泄物、垃圾及有机废水等几大类。
与煤炭相比，生物质原料具有如下特点：①挥发分高而固定碳含量低。
煤炭的固定碳一般为60%左右；而生物质原料特别是秸秆类原料的固定碳在20%以下，挥发分却高达70%左右，是适合热解和气化的原料。
②原料中氧含量高，灰分含量低。
③热值明显低于煤炭，一般只相当于煤炭的1/2～2/3。
④低污染性。
一般生物质硫含量、氮含量低，燃烧过程中产生的SO2、NOx较低。
⑤可再生性。
因生物质生长过程中可吸收大气中的CO2，其CO2净排放量近似于零，可有效减少温室气体的排放。
⑥广泛的分布性。
生物质气化是生物质利用的重要途径之一。
生物质气化技术已有一百多年的发展历史，特别是近年来，对生物质气化技术的研究日趋活跃。
但生物质单独气化存在一些缺点。
首先，生物质的产生存在季节性，不能稳定供给；其次，由于生物质处理后形成的颗粒具有不规则性，在流化床气化炉内不易形成稳定的料层，需要添加一定量的惰性重组分床料如河砂、石英砂等；第三，生物质单独气化时生成较多的焦油，不仅降低了生物质的气化效率，而且对气化过程的稳定运行造成不利影响。
生物质与煤共气化不仅可以很好地弥补生物质单独气化的上述缺陷，同时在碳反应性、焦油形成和减少污染物排放等方面可能会发生协同作用。
1国外的研究与应用情况(1)生物质气化发电生物质气化及发电技术在发达国家已受到广泛重视，如美国、奥地利、丹麦、芬兰、法国、挪威和瑞典等国家生物质能在总能源消耗中所占的比例增加相当迅速。
美国在利用生物质能发电方面处于世界领先地位，美国建立的Battelle生物质气化发电示范工程代表生物质能利用的世界先进水平。
水热炭化技术及其在废水处理中的应用研究进展
水热炭化技术及其在废水处理中的应用研究进展生物质作为一种可再生资源，不仅来源比较广泛而且产量巨大，可以有效缓解目前面临的能源枯竭危机。
同时，合理地资源化利用废弃生物质还能削减焚烧、填埋等传统处理方式对环境带来的污染。
其中，采纳废弃生物质制备生物炭是其资源化利用的有效方法之一。
但传统的生物质炭化方法，需要对含水率高的生物质进行干燥处理，能耗较高，为此越来越多的学者将留意力转移到以水热炭化的方法制备碳质材料。
水热炭化是根据肯定的比例将生物质与水混合后置于反应器内，在肯定的温度、时间和压力条件下，以产生固体产物为目标的水热反应。
它是经过一系列简单的热化学反应，最终将有机物质转化为高含碳产物的过程，产物被称为水热炭。
随着社会经济的进展，以重金属离子、有机物、氮磷氟阴离子为代表的污染物不断随废水进入水体环境，对水生环境和人类健康构成严峻威逼。
采矿、皮革等行业产生的废水中含有汞、铬、镉、锌、铅、铜、镍等重金属离子，其会在水体中长期存在，并会通过食物链在生物体内富集；水体中含有的多环芳烃、卤代烃、有机农药等有机污染物成分简单且具有肯定的毒性；氮磷污染物会造成水体富养分化，同时矿物冶炼加工、肥料的生产都会对水体产生氟污染，这些污染物的存在均会严峻危害生态环境。
因此，对以重金属、有机物、阴离子等为代表的水体主要污染物的脱除已成为水污染治理讨论的重点。
吸附法由于具有操作简洁、成本效益高等优势，在废水处理领域应用广泛。
其中，吸附剂是吸附法得以推广应用的关键。
讨论发觉，可以将农业秸秆、生活垃圾、污泥、动物粪便等废弃生物质经过不同的热化学方法制成生物炭，且所得的生物炭具有孔隙发达、理化性质稳定和官能团丰富等优点，是良好的吸附材料。
其中，水热炭又被认为是具有进展潜力的碳质材料，并被作为绿色吸附材料广泛应用于废水处理领域。
笔者对水热炭的制备工艺和主要工艺参数对水热炭制备的影响进行了介绍，着重总结了水热炭对水体重金属、有机污染物和阴离子污染物的吸附讨论进展，并对其将来讨论方向进行了展望，以期为水热炭今后的讨论和推广应用供应借鉴。
煤或生物质在超临界水中的转化
煤/生物质在超/亚临界水中的转化摘要：由于超/亚临界水具有特殊的物理化学性质，煤或生物质在超/亚临界水的转化技术是一种新兴的利用生物质能的方法，由于其较高的能量利用率和环保特性，正日益受到人们的重视。
本文详细阐述了国内外对于煤或生物质在超临界水中的转化技术现状，指出此技术有望成为新一代的煤或生物质的转化技术。
超临界水（SCW）具有特殊的物理化学性质，总体趋势为密度、粘度、介电常数及对极性无机物的溶解度大大减小，扩散系数、对有机物及气体的溶解度大大增加，这使得具有高的扩散性，使反应体系相界面消失，从而表现出极高的反应活性，基于此，超临界水作为反应介质具有反应速度快、转化效率高等特点。
近年来，使用SCW对煤和生物质进行洁净转化得到了广泛关注，如煤的水热处理；SCW中煤的气化、液化、萃取、脱硫等。
SCW物质过程的潜在优势是能够快速加热有机物料,减少焦炭生成，提高转化率。
其另一个主要优点是高压、高密度的SCW溶液是有机物料气化的理想介质。
1、超临界水性质水的临界温度TC=374.2℃，临界压力为PC=22.1MPa。
当体系的温度和压力超过临界点时，称为超临界水(supercritical water, SCW)。
当体系的温度处于150～370℃，压力处于0.4～22.1MPa，称为近临界水(near-critical water, NCW)。
水的密度是关键参数，它影响水的介电常数、离子积、粘度、溶解度、分子体积、扩散系数、离子化等。
在超临界状态下：压力一定时，当水的温度升高，密度会减小。
温度一定时，当水的压力升高，密度会增大。
相对来说，近临界水需要的温度和压力都较低；作为溶剂，对有机物的溶解性相当于丙酮或乙醇；近临界水的介电常数介于常态水和超临界水之间，因此，近临界水足以既能溶解盐，又能溶解有机物：水与产物易分离，用于分离纯化的耗费很小。
而超临界水极象一个中等强度极性的有机溶剂. 在常规水中易溶解的无机物在超临界水中的离解常数和溶解性却很低. 有机物和气体与超临界水可完全混溶。
水热液化技术
水热液化技术
水热液化技术是一种将有机物通过高压高温下的水热反应转化为可用于生产燃料和化学品的液体能源的技术。
该技术的优点包括可以处理多种废弃物和生物质，同时能够在短时间内转化为高质量的液体燃料。
本文将介绍水热液化技术的原理、应用和前景。
原理：
在水热液化过程中，有机质通过水溶于热水中，在高温下发生裂解、缩合、脱氧等反应，产生液态产品，其中包括生物煤、生物油和生物气。
该技术最适宜的反应条件是：反应温度在240-300℃之间，反应时间为30分钟-1小时，反应压力在5-25 MPa之间。
同时，反应所需的水量大约是有机质的3-4倍。
应用：
水热液化技术在利用生物质转化为能源方面具有广泛的应用前景。
该技术可以处理多种废物，如木材、农作物秸秆、煤炭矸石、纸浆等，还可以处理生物质废弃物，包括动植物油脂、养殖废弃物、城市垃圾等。
液体燃料产品可以用于各种工业应用，如热水供暖、发电厂、汽车燃料等。
此外，还可以生产多种纯化产品，如生物油、生物煤和生物气等化学品。
前景：
随着石油资源的逐渐枯竭，使用水热液化技术生产可再生燃料的需求逐渐增加。
从经济、环境和能源方面来看，水热液化技术将在未来的能源产业中发挥重要作用。
目前，一些国家如美国、澳大利亚和日本等已经开始采用水热液化技术生产生物燃料。
中国也在积极推进该技术，大力开展研发，培育有关产业的发展，推进环境友好型经济的建设。
总的来说，水热液化技术在绿色能源产业的不断发展中具有重要的战略性和前途性。
水热炭化工艺流程
01
水热炭化技术概述及其重要性
水热炭化技术的定义与原理
• 水热炭化技术是一种在高温高压条件下，利用水热介质对生物质原料进行炭化处理的技术 • 水热介质：水、有机溶剂等 • 炭化过程：将生物质原料中的有机物质转化为炭的过程 • 高温高压条件：温度通常在150-300℃，压力通常在1-10MPa
• 20世纪60年代：美国科学家研究发 现，水热条件下生物质原料的炭化产物 具有高能量密度和良好的稳定性 • 20世纪70年代：日本科学家开始对 水热炭化技术进行深入研究，并将其应 用于生物质能源领域
水热炭化技术在能源领域的应用价值
• 水热炭化技术具有高能量密度、高转化效率和环境友好等优点，在能源领域具有广泛的应用价值 • 高能量密度：水热炭化产物的能量密度远高于传统化石燃料，可作为一种高性能的能源载体 • 高转化效率：水热炭化技术可将生物质原料中的有机物质完全转化为炭，转化效率高 • 环境友好：水热炭化过程中产生的温室气体排放较低，有利于减缓全球气候变化
反应时间对炭化产物性能的影响
反应时间对炭化产物能量密度的影响
• 随着反应时间的延长，炭化产物的能量密度逐渐提高，但当时间达到一定值后，能量密度 的提高幅度减小 • 原因：反应时间延长，有利于生物质原料中的有机物质充分转化为炭，提高产物的能量密 度；但当时间达到一定程度后，过长的反应时间可能导致炭化产物中的不稳定结构增多，影 响产物的能量密度
04
水热炭化技术的优势与挑战
水热炭化技术的优势及其原因
水热炭化技术优势的原因
• 高温高压条件：水热炭化技术在高温高压条件下进行，有利于生物质原料中的有机物质转化为 炭 • 水热介质：水热炭化过程中使用水作为反应介质，有利于生物质原料中的有机物质水解、脱水、 缩合等反应的进行
生物质水热转化技术
生物质水热转化技术在国家自然科学基金项目（批准号：52070116）等资助下，清华大学资源环境课题组张衍国教授、周会特别研究员等人在生物质水热转化领域取得新进展。
相关研究成果以“温度压力解耦条件下由纤维素水热合成亚微米碳球（Decoupled temperature and pressure hydrothermal synthesis of carbon sub-micron spheres from cellulose）”为题，于2022年6月24日发表在《自然•通讯》（Nature Communications）期刊上。
木质纤维素生物质，如木材、草和农业废弃物，由纤维素、半纤维素和木质素组成，是一种可再生的碳中性资源。
纤维素作为木质纤维素生物质的主要成分，是自然界中最丰富的可持续碳源，同时也是纸和棉基纺织品的主要成分。
因此，纤维素的高附加值利用有望有助于缓解能源危机和全球变暖，助力我国“双碳”目标的实现。
纤维素的水热转化可产生固体碳材料、液体生物油和可燃气体。
其中的固体碳材料，可用于净水、储能和催化等多种领域。
传统的批次反应器因其操作简单、适用性强，被广泛用于纤维素等固体物质的水热过程研究。
然而，在典型的批次反应器中，温度和压力是耦合的，因此很难单独控制这两个变量，这导致所谓的现有研究的“温度效应”可能本质上是温度和压力的综合影响。
针对传统水热反应温度压力耦合的问题，研究团队提出温度和压力解耦的概念，设计并开发了一套温度压力解耦的水热反应系统，实现了水热过程温度和压力的解耦。
基于此，研究团队发现恒定高压对于纤维素转化具有显著的促进作用，设计了纤维素的低温快速转化路线，揭示了解耦条件下的反应机理。
在温度压力解耦的路线下，纤维素可以在约117℃时降解，低于传统路线近100℃。
在该路线下，纤维素衍生的亚微米碳球的生产不需要任何等温时间，与需要几个小时的传统工艺相比，大大节省了反应时间。
全生命周期评估表明，与传统方法相比，该方法显示出更高的能源效率，能够有效减少温室气体排放。
水热炭工艺
水热炭工艺水热炭工艺是一种利用水热反应将生物质转化为高质量炭材料的技术。
在这个过程中，水热反应在高温高压的环境下，促使生物质中的碳化过程加速，从而形成具有高孔隙度和高比表面积的炭材料。
这种工艺在能源利用、环境保护和资源回收等方面具有重要的意义。
水热炭工艺的基本原理是通过水热反应将生物质中的有机物转化为无机炭。
在这个过程中，水热条件下的高温高压环境可以促进生物质中的碳化反应。
水热反应的温度通常在200℃至400℃之间，压力可以达到几十到几百个大气压。
在这个条件下，生物质中的有机物经过水热反应，发生脱水、脱氧和碳化等一系列反应，最终生成炭材料。
水热炭工艺的优点之一是可以利用各种生物质资源，如农林废弃物、生活垃圾和工业废弃物等。
这些生物质资源通常被视为废弃物，如果不加以处理就会对环境造成污染。
而通过水热炭工艺，可以将这些废弃物转化为高质量的炭材料，从而实现资源的回收利用。
水热炭工艺的另一个优点是可以减少对传统石油、煤炭等化石能源的依赖。
传统能源的开采和利用对环境造成了严重的影响，如空气污染、温室气体排放等。
而水热炭工艺可以将生物质转化为炭材料，这种炭材料可以用作固体燃料，替代传统的石油和煤炭，减少对化石能源的需求。
水热炭工艺还可以产生其他附加价值的产物。
在水热反应过程中，除了生成炭材料外，还会生成一些气体和液体产物。
这些产物可以用于燃料气的生产、化工原料的制备等。
因此，水热炭工艺不仅可以实现生物质资源的回收利用，还可以产生其他有用的产物。
水热炭工艺在能源利用、环境保护和资源回收等方面具有广阔的应用前景。
通过这种工艺，可以实现生物质资源的高效利用，减少对传统化石能源的依赖，同时还可以减少废弃物对环境的污染。
因此，水热炭工艺在可持续发展和环境保护方面具有重要的意义。
水热炭工艺是一种将生物质转化为高质量炭材料的技术。
通过水热反应，在高温高压的环境下，促使生物质中的碳化过程加速，从而形成具有高孔隙度和高比表面积的炭材料。
生物质水热炭化
Production of solid biochar fuel from waste biomass by hydrothermal carbonizationZhengang Liu a ,Augustine Quek a ,S.Kent Hoekman b ,R.Balasubramanian a ,⇑a Department of Civil and Environmental Engineering,National University of Singapore,1Engineering Drive 2,E1A 07-03,Singapore 117576,Singapore bDivision of Atmospheric Sciences,Desert Research Institute (DRI),2215Raggio Parkway,Reno,NV 89512,USAh i g h l i g h t s"Hydrothermal carbonization was employed to upgrade fuel quality of waste biomass."The improved fuel qualities of the biochars are similar to those of lignite."Hydrothermal carbonization narrowed the differences among different biomasses."The biochars have the potential to be used as a coal substitutes for heat production.a r t i c l e i n f o Article history:Received 2May 2012Received in revised form 23July 2012Accepted 31July 2012Available online 11August 2012Keywords:Biomass upgrading Energy density Biochar Solid fuelCombustion kineticsa b s t r a c tThe application of biomass-derived energy is gaining in importance due to decreasing supply of fossil fuels and growing environmental concerns.In this study,hydrothermal carbonization was used to upgrade waste biomass and increase its energy density at temperatures ranging from 150to 375°C and a residence time of 30min.The produced biochars were characterized and their fuel qualities were evaluated.The biochars were found to be appropriate for direct combustion/co-combustion with low rank coals for heat production.Chemical analysis showed that the pre-treated biomass has improved fuel qualities compared to the raw biomass,such as decreased volatile matter/(volatile matter +fixed carbon)ratio,increased carbon content and lower ash content.The energy density of biochar increased with increasing hydrothermal temperature,with higher heating values close to that of lignite.The evolution of biomass under hydrothermal carbonization,as determined by FT-IR and 13C NMR,showed that most hemicellulose and cellulose were decomposed at below 250°C while the degradation of lignin only occurs at higher temperatures.The aromaticity of biochars increased with increasing temperature,and considerable amounts of lignin fragments remained in the biochars after supercritical water treatment.The biochars had increased ignition temperatures and higher combustion temperature regions compared to raw biomass feedstock.An optimum temperature of 250°C was found for hydrothermal carbonization of waste biomass for the production of biochars for heat generation.The present study showed that hydrothermal carbonization narrowed the differences in fuel qualities among different biomass feed-stocks.It also offers a promising conversion process for the production of high energy density biochar which has potential applications in existing coal-fired boilers without modifications.Ó2012Elsevier Ltd.All rights reserved.1.IntroductionLignocellulosic biomass,the most abundant organic materials on earth,has enormous potential as a feedstock for the production of fuel,heat and electrical power.The attractiveness of lignocellu-losic biomass has increased in recent years due to rapid depletion of conventional fossil fuels and growing concerns of environmental pollution and climate change.Biological and thermochemical con-versions are two major conversion technologies used for lignocellu-losic pared to biological processes,thermochemical treatment has several advantages such as short processing times and high product yields.Among thermochemical conversion meth-ods,direct combustion and co-combustion with low rank coals are widely investigated,as these methods have less risk,are less expen-sive,and have the highest potential among short term options for realizing biomass energy utilization [1].Several reviews on biomass combustion for heat generation conclude that direct combustion is not a satisfying option owing to inherent properties of biomass feedstocks such as high moisture and oxygen contents,and high alkaline earth metal content [1–3].For instance,during biomass combustion,the high moisture lowers combustion temperature as well as increase CO emission,causing serious air pollution [1].The high content of alkali and alkaline earth metals in biomass0016-2361/$-see front matter Ó2012Elsevier Ltd.All rights reserved./10.1016/j.fuel.2012.07.069Corresponding author.Tel.:+6565165135;fax:+6567744202.E-mail address:ceerbala@.sg (R.Balasubramanian).can cause severe fouling and agglomeration inside boilers.Further-more,seasonal variations affect the availability of biomass feed-stock,while the wide diversity of physical shapes,compositions and energy densities among different biomass poses serious challenges in transportation,storage and sizing of feedstocks.To overcome these problems,it is helpful to pre-treat or modify the biomass feedstock prior to combustion to homogenize different biomass feedstocks into a form similar to coal to accommodate existing coal-fired plants.In this way,pre-treatment also provides environmental,social and economical benefits of biomass energy.Hydrothermal treatment offers significant advantages for bio-mass conversion including the lack of an energy-extensive drying process,high conversion efficiency and relatively low operation temperature among thermal methods.Hydrothermal treatment of biomass generates liquid(bio-oil),gaseous(mainly carbon diox-ide),aqueous,and solid products(biochar).The distributions and properties of these product streams are strongly dependent on treatment conditions.Currently most attention is paid to the liquid and gaseous products and many processes have been developed and optimized to improve the quality and increase the quantity of these two target products[4–8].However,due to the high acid-ity and complex composition,the bio-oil cannot be used directly, but requires further upgrading.As for the gaseous product,the low yield and complicated separation and purification process also limit its widespread application in practice.Under this situation, realizing high-value application of biochar may provide some advantages and a viable option to enhance the biomass utilization effipared to bio-oil and gaseous products,only a few investigations have been carried out on solid biochar obtained from waste biomass.Biochar is generally produced as a byproduct during biomass liquefaction to generate bio-oil,or gasification to generate syngas[9,10].Instead of waste biomass feedstocks,pure biomass substances,including glucose and cellulose,are hydro-thermally carbonized with the aim of biochar production.These biochars exhibit some unique physicochemical properties com-pared to biochars from conventional carbonization and are applied in several value-added applications[11,12].To date,no report is available about biochar production from hydrothermal treatment of waste biomass with the specific inten-tion of solid fuel application.In the present study,several hydro-thermal biochars from waste biomass(coconutfiber and dead eucalyptus leaves)were produced under different carbonization conditions.The physicochemical properties were characterized and combustion behavior of the resulting biochars was investigated to evaluate the feasibility for solid fuel application. In addition,the conversion of biomass feedstocks under hydrother-mal carbonization was also examined by FI-IR and13C NMR techniques.2.Experimental2.1.MaterialsCoconutfiber and dead eucalyptus leaves were selected as the representative waste biomass due to their high production poten-tial in Singapore.The biomass was crushed to less than5mm and then dried at105°C for24h for subsequent hydrothermal carbon-ization.The results of the ultimate and proximate analysis of coco-nutfiber and leaves are shown in Table1,with lignite sample for comparison.2.2.Biochar preparationThe biochar was prepared in a laboratory scale semi-batch500-ml Parr autoclave reactor(USA).Around10g of biomass(coconut fiber/eucalyptus leaves)was loaded with100ml de-ionized water into the reactor and the autoclave was heated to desired tempera-ture(150–375°C).The reactor was held atfinal temperature for 30min and then quickly cooled down to room temperature.The biochar was recovered as solid residue by vacuumfiltration and dried in an oven at105°C for24h.The biochar sample was desig-nated as‘‘C-xxx’’or‘‘L-xxx’’,where the C and L refer to respective biochar derived from coconutfiber and leaves and‘‘xxx’’shows centigrade temperature of hydrothermal carbonization.2.3.CharacterizationElemental analysis(C,H,N and S)was determined on VarioMac-ro Cube Elementar(USA).The proximate analysis was conducted using5E-MAG6600Automatic Proximate Analyzer(China).The infrared spectrum(as KBr disk)was recorded in the wave number range of4000–400cmÀ1with a Nicolet Nexus670Spectrophotom-eter(USA)at room temperature.The cross polarization/magic angle spinning(CP/MAS)13C NMR spectrum of biomass and correspond-ing biochar was measured using a solid state spectrometer JEOL CMX-300(Japan).The measurement conditions were as follows: spinning speed in excess of12kHz,constant time of2ms,pulse repetition time of7s and scan number of10,000.Chemical shifts are in parts per million(ppm)referenced to hexamethylbenzene. Combustion analysis was conducted on a differential thermogravi-metric analyzer TQ-500(USA),with which weight loss and rate of weight loss of the sample as functions of time or temperature were recorded continuously in the range of room temperature to800°C. The experiments were carried out at atmospheric pressure,under air atmosphere at a linear heating rate of20°C/min.In order to eliminate mass and heat transfer effects,high airflow rate (150ml/min)and small mass(around10mg with the particle size less than150l m)were used in combustion experiments.3.Results and discussion3.1.Yield and chemical composition of the biocharBiochar yield as a function of hydrothermal temperature is shown in Fig.1.Temperature plays a vital role in the biochar yield; similar trends of biochar yield vs.temperature were observed for coconutfiber and eucalyptus leaves.The biochar yield decreased rapidly with increasing temperature in the temperature range from 150to300°C,followed by a further gradual decrease to35.3%and 28.1%for coconutfiber and eucalyptus leaves up to375°C,respec-tively(C-220,250,300,350and375samples and L-200,250,300, 350and375samples were selected for the following analysis).Proximate and ultimate analysis of coconutfiber,eucalyptus leaves and their derived biochars are summarized in Table1(lig-nite for comparison).As expected,the carbon content and energy density increased while the oxygen content decreased dramatically with increasing hydrothermal temperature;changes that are ex-pected to improve combustion properties of the biochar[1].A slight decrease of hydrogen content was also observed with increasing temperature.To examine the changes in atomic compo-sition,the atomic H/C and O/C ratios of raw biomass and corre-sponding biochar are plotted in a van Krevelen diagram,as illustrated in Fig.2.The H/C and O/C ratios decreased with increas-ing hydrothermal temperature.Even for the biochar obtained at relatively low temperature of200°C,the values were far lower than that of raw biomass.It is noteworthy that the values of H/C and O/C ratios of the biochar obtained from250°C treatment were lower than that of the lignite sample used in present study. Generally,a fuel with low H/C and O/C ratios is favorable because of the reduced energy loss,smoke and water vapor during the944Z.Liu et al./Fuel103(2013)943–949combustion process.From Fig.2,it is expected that the biochars have better fuel qualities than either raw biomass or lignite.Due to the decrease in the number of low energy H A C and O A C bonds and increase of high energy C A C bond,the energy density of biomass feedstock was improved,as indicated by the calculated higher heating values(HHVs)of the biochars.From the proximate analysis results it can be seen that hydro-thermal carbonization decreased the fraction of volatile matter in combustible carbon(volatile matter/(volatile matter+fixed car-bon)significantly and the values of C-300(0.56)and L-350(0.62) were very close to that of the lignite sample(0.54).High volatile matter content is a cause for reduced combustion efficiency and in-creased pollutant emission when biomass is directly combusted [1].When biomass co-combusts with low rank coal,a big differ-ence in the volatiles ratio(volatile matter/(volatile matter+fixed carbon))between biomass and the coal also leads to separated combustion regions;with biomass being combusted at low tem-peratures while coal combusts at high temperatures.The similar proximate composition and HHV of biochars to lignite(Table1) imply that the biochars obtained in the present study can be used directly for coal-fueled boilers without significant modifications. Moreover,the combination of decreased oxygen and volatile mat-ter content of biochars can potentially reduce the release of inor-ganic vapors during combustion,compared to the parent biomass [1].As for the ash content,it decreased with increasing tempera-ture to300°C for coconutfiber and350°C for eucalyptus leaves, and then increased up to375°C.For hydrothermal carbonization of biomass,the behavior of inorganics is still largely unknown. However,from the decreased biochar yield and decreased ash con-tent,it can be seen that some fraction of ash was dissolved in the water at lower temperatures.Similarly,in a study on the de-min-eralization of lignite,a significant fraction of inorganics contained in lignite was found to be dissolved in the water after hydrother-mal treatment at sub-critical temperatures[13].The ash analysis indicated that at higher temperatures and pressures,including supercritical water conditions(obtained at375°C in present study) minerals in the ash became less soluble and precipitated from solu-tion.This observation is consistent with a previous report[14],and suggests that carbonization conditions should be optimized to ob-tain a biochar with the desired ash content.The energy densification and energy yield of the produced bio-char were also evaluated in the present study.According to the ap-proach suggested by Yan et al.,the energy densification was determined by energy content of the biochar divided by the energy content of raw biomass and the energy yield was defined as the biochar yield multiplied by the energy densification[15].As shown in Table1,generally the energy densification increased with increasing temperature,from a low value of1.34to a high1.66 and from1.33to1.55for coconutfiber and eucalyptus leaves de-rived biochars,respectively.The highest energy yield was obtained at the lowest temperature used.Energy yield generally decreased with increasing temperature with the lowest energy yield atTable1Proximate analysis,ultimate analysis and heating value of coconutfiber,eucalyptus leaves and their derived-biochars(lignite for comparison).Sample VM(%)Ash(%)FC a(%)N(%)C(%)H(%)S(%)O a(%)HHV(kJ/mol)ED EY(%)Coconutfiber80.98.111.00.9047.75 5.610.2345.5118.4––C-22069.8 6.224.00.9062.47 5.280.2631.0924.7 1.3476.67 C-25067.9 5.027.10.9867.10 5.200.2926.4326.7 1.4565.70 C-30053.6 4.342.1 1.1373.22 5.090.3520.2129.4 1.6065.00 C-35056.6 4.938.5 1.1773.37 4.520.3620.5828.7 1.5655.78 C-37542.68.648.8 1.2378.20 4.310.3315.9330.6 1.6659.00 Eucalyptus leaves79.210.510.3 1.2346.96 6.220.7744.8218.9––L-20072.57.320.2 1.3761.11 6.130.6530.7425.3 1.3387.34 L-25070.1 6.923.0 1.4462.30 5.470.4430.3525.0 1.3261.12 L-30061.27.131.7 1.6268.87 6.000.7222.7928.7 1.5161.32 L-35056.29.933.9 1.6070.50 5.93 1.5220.4529.4 1.5547.84 L-37543.214.242.6 1.6472.19 4.81 1.5119.8528.7 1.5142.78 Lignite48.7610.2640.98 1.7461.64 5.720.7730.1325.0––VM=volatile matter;FC=fixed carbon;ED=energy densification;EY=energy yield.Higher heating value(HHV)=0.3491C+1.1783H+0.1005SÀ0.1034OÀ0.0151NÀ0.021A where C,H,S,O,N and A are carbon,hydrogen,sulfur,oxygen,nitrogen and ash content in wt.%,respectively.a Calculated by difference.Z.Liu et al./Fuel103(2013)943–94994555.78%and42.78%for coconutfiber at350°C and eucalyptus leaves at375°C,respectively.Hoekman et al.reported that the en-ergy yield of hydrothermal char from a mix of Jeffrey and White Fir did not vary greatly over the temperature range of215–295°C with the yield from70%to77%[16].In contrast,the energy yield from coconutfiber and eucalyptus leaves varied significantly from 76.67%to65.00%and87.34%to61.32%within the temperature range of200–300°C,respectively.The different hydrothermal car-bonization conditions and the different starting biomass feed-stocks could explain these observations.The results presented here show that the fuel qualities of the biochars are improved compared to their respective parent bio-mass,having decreased oxygen,volatile matter and ash contents, and increased carbon andfixed carbon content.The resulting bio-char has the potential to be a satisfactory solid fuel for either direct combustion or co-combustion with lignite.The high biochar yield coupled with lower operation temperatures suggests that hydro-thermal carbonization affords a promising alternative for produc-tion of a solid fuel from waste biomass,which can potentially be combusted in existing coal-fired plants[17].As for the biomass feedstock for solid fuel production,coconutfiber appears to be more suitable than eucalyptus leaves,due to its lower nitrogen and sulfur contents.3.2.FT-IR analysisFig.3shows the FT-IR spectra of raw biomass and the biochars, with the assignment of the peaks based on IR mentor Pro2.0and related publications[11,18,19].The presence of alcohol and phenol structure was indicated by the peak at2927and2854cmÀ1which was ascribed to the C A H stretching vibration and deforming vibration,-pared to coconut-derived biochars,the relatively strong adsorption of leaves-derived biochars at these two wave numbers was due to the presence of wax in leaves.This observation was consistent with the elemental analysis[20].For both biochars,these two peaks weakened with increasing temperature,suggesting that dehydra-tion reactions were enhanced with increasing temperature.The peak at1064cmÀ1was ascribed to the b-glycosidic bond in cellu-lose and hemicellulose.The intensity of this peak decreased signif-icantly with increasing temperature,indicating that nearly all hemicellulose and cellulose decomposed at temperatures of 250°C and greater.The strong C A O band at1103cmÀ1was as-signed to A OCH3groups in lignin.This band also weakened with increasing temperature,indicating a loss of A OCH3by deoxygen-ation reactions.The peaks around1612and1449cmÀ1in the raw biomass corresponded to the C@C stretching of aromatic groups in lignin.These peaks were present in all the biochars ana-lyzed,implying that some lignin fragments and intermediate struc-tures remained in the resulting biochars,e.g.,lignin did not totally decompose under the hydrothermal conditions that were investi-gated.The absorption band around3375cmÀ1indicates the exis-tence of free and intermolecular bonded hydroxyl groups A OH in raw biomass.The hydroxyl content in biochar decreased with increasing temperature and almost disappeared at375°C treat-ment,implying an increase in hydrophobicity of biochar compared to raw biomass.High hydrophobicity is important for fuel storage and handling,as this affords higher resistance to humidity.3.3.13C NMR analysisFig.4shows13C CPMAS NMR spectra of coconutfiber and coco-nutfiber-derived biochars.This provides a valuable complemen-tary method to FT-IR analysis in describing of biomass conversion during hydrothermal carbonization.The spectra were sampled every1ppm over a chemical shift range of200ppm.Since the13C resonances in solid NMR spectra were in general broad compared to solution NMR,this sampling resolution was sufficient to represent all the resonances and does not result in any‘‘binning’’that partitions the resonances into groups.946Z.Liu et al./Fuel103(2013)943–949The NMR spectrum of coconut fiber gave sharp characteristic peaks of hemicellulose,cellulose and lignin [21–24].The peaks appearing in the range from 60to 105ppm were ascribed to cellulose and hemicellulose.The peak at 105ppm was ascribed to cellulose C-1and the peak around 102ppm,which overlapped with 105ppm,was ascribed to hemicellulose.The strong peak appearing at 73ppm (the C2,C3and C5of carbohydrate)can be seen as a representative of both cellulose and hemicellulose.Fig.4shows that the decomposition of such carbohydrates occurs at low temperature.At 220°C,the intensities of the peaks de-creased significantly;they were undetectable above 250°C.This observation is consistent with the disappearance of the resonance peak at 88ppm,which was ascribed to the C-4of crystal-interior cellulose.Peaks in the range from 116to 154ppm and 55ppm (methoxyl group)were ascribed to the lignin.The peaks appearing at 144and 154ppm were ascribed to the C3/C5of syringyl unit (not ether-linked)and C3/C5of ether-linked syringyl units,respec-tively.The peaks at 55ppm and 116ppm (C-5guaiacyl or C3and C5of 4-hydroxyphenyl unit)were present in the spectrum of coconut fiber.Their intensities remained unchanged after 300°C treatment,indicating that lignin degraded after hemicellulose and cellulose were degraded.Therefore,biochar C-300contained considerable amount of lignin segments or unreacted lignin.Unlike cellulose and hemicellulose,the decomposition temperature of lignin is higher than its melting temperature.Melting of lignin forms droplets immiscible in hot compressed water and these lignin melts precipitated before degradation.Similar results have also been observed during the hydrothermal dissolution of willow in hot compressed water [25].The biochar composition exhibited a progressive trend of deple-tion of functional groups in the range of hemicellulose,cellulose and lignin substructures.Above 300°C,carbon in the biochar was mainly in the form of aromatics,with the degree of aromatic-ity increasing with increasing temperature.After carbonization at 375°C,the peaks at 145(guaiacyl C3,C4)and broad peak at 35ppm (CH x )almost disappeared,indicating that the C-375was an almost purely aromatic char with very little organic oxygen and hydrogen substituents.From the degree of carbon saturation,the spectra can be divided into aliphatic (0–109ppm)and aromatic (109–154ppm)regions [26].As a direct comparison,the peaks weakened and then disap-peared in the aliphatic region,and peaks only remained in the aro-matic region as the temperature increased up to 375°C.This observation gave evidence that the aliphaticity decreased and aro-maticity increased with increasing hydrothermal carbonization temperature as a result of deoxygenation and dehydration reactions.bustion behavior of biocharFig.5shows the DTG curves for the coconut fiber,eucalyptus leaves and their derived biochars,with the combustion parameters summarized in Table 2.From the curves,it can be seen that the combustion behavior of the biomass changed significantly after hydrothermal carbonization,especially for the coconut fiber.For coconut fiber,a sharp DTG peak was observed centered at about 295°C and a weight loss of 82%was measured at 326°C,where sig-nificant weight loss was no longer detected.The combustion of coconut fiber involves mainly volatile matter combustion,which was ignited at a low temperature of 273°C due to the high reactiv-ity of volatile matter.The rapid weight loss of coconut fiber within a short time at the lower temperature range implies that there was incomplete combustion with low efficiency and high pollutant emission (CO and PAH)[1].Compared to coconut fiber,the reactivity of the biochar de-creased,resulting in a higher ignition temperature and combustion in a wider temperature range.The elevated combustion tempera-ture with high weight loss rate implies improved combustion safety,increased combustion efficiency and decreased pollutant emission.These combustion characteristics are significant improvements over raw biomass feedstock as a fuel [1–3].Among all coconut fiber-derived biochars,C-375(produced from supercritical water)was unique with the lowest maximum weight loss rate and burnout and the highest ash content.In the DTG curve of C-375,a wide peak with maximum weight loss rate (0.47%/°C)was observed at 505°C and a minor weight loss was also present at 728°C which was attributed to the decomposition ofthe13C NMR spectra of coconut fiber and coconut fiber derived-biochars obtained from different hydrothermal temperatures.103(2013)943–949947ash content.Similar results were also observed for eucalyptus leaves and leaves-derived biochars.For the raw eucalyptus leaves, two separated peaks were observed due to the large differences in reactivities of the components.Around60%weight loss was ob-served to occur at360°C due to the high reactivity.After hydro-thermal treatment,the height of thefirst peak in the DTG curve decreased and the maximum weight loss rate shifted to the second peak(0.82%/°C for leaves and higher than0.98%/°C for the biochars except L-375).Among all leaves-derived biochars,the maximum weight loss rate was achieved in L-250(similar to C-250).L-375 has the lowest burnout and widest combustion range beyond tem-perature605°C.For evaluation of the ignition performance,igni-tion index(D i)of the biomass and biochar was calculated with the following equation[27]:D i¼R max=ðt maxÂt iÞð1Þwhere R max is the maximum weight loss rate,t max and t i are corre-sponding to the time of the maximum weight loss rate and ignition temperature,respectively.Higher values of ignition index(D i)are indicative of better igni-tion performance.As shown in Table2,the coconutfiber derived-biochars have lower D i values than coconutfiber,and the D i values decreased with increasing temperature.For the eucalyptus leaves, the ignition index increased up to a temperature of250°C and then decreased with further increase in temperature.The highest igni-tion index value(0.78)was obtained at250°C hydrothermal treat-ment of the leaves.Additionally,by comparing the combustion behaviors of the biochars,similar combustion behaviors were observed.Hydrother-mal carbonization has the ability to homogenize the different bio-mass feedstocks considerably,which increases the potential for biomass utilization.At supercritical conditions,the low combus-tion reactivity together with the high ash content and low biochar yield showed that very high temperatures and pressures were not favorable for biochar fuel production from biomass[14].Consider-ing combustion behavior and energy densification of the biochar as well as energy yield,hydrothermal carbonization at250°C was optimal for solid fuel production for combustion from biomass feedstocks.4.ConclusionsBiochars with improved fuel qualities were successfully pro-duced from hydrothermal carbonization of waste biomass.Deoxy-genation and dehydration reactions cause biochars to have high hydrophobicity and increased carbon content compared to the raw feedstocks.Hydrothermal carbonization was able to homoge-nize biomass feedstocks of different origins,and the biochars have considerably higher energy densities–comparable to lignite.For the evolution of biomass under hydrothermal carbonization, cellulose and hemicellulose were almost totally decomposed at temperatures lower than250°C,prior to lignin decomposition (around300°C).Some lignin fragments and decomposition inter-mediates remained in the biochar even after supercritical water carbonization.The combustion behaviors of biochars were distinct from raw biomass,with increased maximum weight loss rate,ele-vated ignition temperature and wide combustion ranges at higher temperatures.This combustion behavior suggests that the pro-duced biochars are appropriate for combustion or co-combustion with lignite in existing coal-fueled boilers for heat generation.In addition,based on the biochar yield and observed combustion behavior,250°C was the optimal temperature for solid fuel pro-duction from waste biomass by hydrothermal carbonization. AcknowledgementsThis work wasfinancially supported by the National Environ-mental Agency of Singapore and M3TC(Minerals,Metals and Materials Technology Centre)at NUS.References[1]Khan AA,Jong W,Jansens PJ,Spliethoff H.Biomass combustion influidized bedboilers:potential problems and remedies.Fuel Process Technol 2009;90:21–50.[2]Ayhan bustion characteristics of different biomass fuels.Prog EnergyCombust Sci2004;30:219–30.[3]Hanzade bustion characteristics of different biomass materials.Energy Convers Manage2003;44:155–62.[4]Akhtar J,Amin NAS.A review on process conditions for optimum bio-oil yieldin hydrothermal liquefaction of biomass.Renew Sust Energy Rev 2011;15:1615–24.[5]Andrea K.Hydrothermal biomass gasification.J Supercrit Fluid2009;47:391–9.[6]Azadiand P,Farnood R.Review of heterogeneous catalysts for sub-andsupercritical water gasification of biomass and wastes.Int J Hydrogen Energy 2011;36:9529–41.[7]Hashaikeh R,Fang Z,Butler IS,Kozinski JA.Sequential hydrothermalgasification of biomass to hydrogen.Proc Combust Inst2005;30:2231–7. [8]Muangrat R,Onwudili JA,Williams PT.Influence of alkali catalysts on theproduction of hydrogen-rich gas from the hydrothermal gasification of food processing waste.Appl Catal B:Environ2010;100:440–9.[9]Meyer S,Glaser B,Quicker P.Technical,economical,and climate-relatedaspects of biochar production technology:a literature review.Environ Sci Technol2011;45:9473–83.[10]Onwudili JA,Williams PT.Role of sodium hydroxide in the production ofhydrogen gas from the hydrothermal gasification of biomass.Int J Hydrogen Energy2009;34:5645–56.[11]Liu Z,Zhang F-S,Wu J.Characterization and application of chars producedfrom pinewood pyrolysis and hydrothermal treatment.Fuel2010;89:510–4.[12]Titirici M,Antonieti M.Chemistry and materials options of sustainable carbonmaterials made by hydrothermal carbonization.Chem Soc Rev 2010;39:103–16.[13]Wild T.Demiberalisierung und mechnisch/thermische entwasserung vonbraunkohlen und biobrennstoffen.Germany:Universitat Dortmund;2006.p.101–45.[14]Funke A,Ziegler F.Hydrothermal carbonization of biomass:a summary anddiscussion of chemical mechanisms for process engineering.Biofuel Bioprod Bioref2010;4:160–77.[15]Yan W,Acharjee TC,Coronella CJ,Vasquez VR.Thermal pretreatment oflignocellulosic biomass.Environ Progress Sustain Energy2009;28:435–40. [16]Hoekman SK,Broch A,Robbins C.Hydrothermal carbonization(HTC)oflignocellulosic biomass.Energy Fuels2011;25:1802–10.[17]Libra JA,Ro KS,Kammann C,Funke A,Berge ND,Neubauer Y,et al.Hydrothermal carbonization of biomass residuals:a comparative review of the chemistry,processes and applications of wet and dry pyrolysis.Biofuels 2011;2:89–124.[18]Eberhardt TL,Catallo WJ,Shupe TF.Hydrothermal transformation of Chineseprivet seed biomass to gas-phase and semi-volatile products.Bioresource Technol2010;101:4198–204.[19]Tandy S,Healey JR,Nason MA,Williamson JC,Jones DL,Thain SC.FT-IR as analternative method for measuring chemical properties during composting.Bioresource Technol2010;101:5431–6.[20]Naik S,Goud VV,Rout PK,Jacobson K,Dalai AK.Characterization of Canadianbiomass for alternative renewable biofuel.Renew Energy2010;35:1624–31.[21]Gilardi G,Abis L,Cass AEG.Carbon-13CP/MAS solid-state NMR and FT-IRspectroscopy of wood cell wall biodegradation.Enzyme Microb Technol 1995;17:268–75.Table2Combustion parameters of biomass feedstocks and their derived biochars.Sample T i(°C)T m(°C)T b(°C)R max(%/°C)D i(Â10À2)Coconutfiber273295326 2.39 1.48C-220295450472 1.640.59C-250372436472 1.710.49C-300400458478 1.670.42C-3504104515120.940.24C-3753935055800.470.11Eucalyptus leaves2533124560.820.52L-200288414449 1.590.64L-250288423445 1.970.78L-300374417449 1.150.35L-3503694104700.980.30L-3754285225810.550.11T i=ignition temperature;T b=burnout temperature;D i=ignition index.948Z.Liu et al./Fuel103(2013)943–949。
生物质热化学转化气化技术和热解技术的特点和比较
生物质热化学转化气化技术和热解技术的特点和比较
生物质热化学转化气化技术和热解技术都是将生物质转化为可用能源的方法，但它们之间存在一些特点和区别。
1. 热化学转化气化技术特点：
- 过程中生物质在高温和缺氧或氧气限制条件下进行燃烧和气
化反应。
- 可以利用不同的气化剂（如空气、氮气、水蒸气等）使气化
产物的组成和能量利用程度发生变化。
- 通过气化反应生成的气体主要由CO、H2、CO2、CH4等组成，称为合成气或气化气，可以作为燃料或化工原料。
- 气化过程中可以控制气化温度、压力、氧化还原度等参数，
以达到最佳气化效果。
2. 热解技术特点：
- 过程中生物质在高温和无氧条件下进行热分解反应。
- 热解过程中产生的主要产物为固体炭和液体活性炭，以及气
体和水分。
- 热解温度较高，一般在300℃以上，可以得到较高的生物质
炭收率，但液体产品含量较低。
- 热解底温可以用于生物质炭的制备或固体废弃物的焚烧。
比较：
- 气化技术可以产生合成气，可以直接用于发电或者气体燃料，而热解技术主要产生固体炭和液体产物，需要进一步加工才能利用。
- 气化技术适用于各种燃料和生物质原料，热解技术更适用于
纤维素质和木质材料。
- 气化技术对反应条件和气化剂的选择要求较高，而热解技术的控制难度相对较低。
- 气化技术需要较高的能量输入，但能够实现高效能源转化。
热解技术能量要求较低，但能源转化效率较低。
根据具体的应用需求和资源特点，选择适当的技术进行生物质转化。
生物质能源的制备与利用
生物质能源的制备与利用随着环保理念的逐渐深入人心，生物质能源的制备与利用也越来越成为人们关注的焦点。
生物质能源是指通过将植物、动物及其代谢产物等有机物直接或间接转化而成的能源，如木材、秸秆、沼气等。
本文将讨论生物质能源的制备工艺与利用方法，以及其在环保领域的应用。
一、生物质能源的制备工艺1.生物质热解法生物质热解法是将生物质加热到高温下，通过热分解将其转化为液体、固体和气体三种物质。
其中，液体为生物质液体燃料，固体为炭，气体为生物质气体燃料。
生物质热解法的优点是工艺简单，成本低，易于掌握，但是排放的废气和废水对环境造成的污染较为严重。
2.生物质气化法生物质气化法是将生物质在缺氧或微氧环境下加热，使其发生氧化还原反应，生成可燃性气体和炭。
可燃性气体主要由一氧化碳、氢气和甲烷组成，具有高热值、易于储存和运输等特点，可用于燃气发电等领域。
3.生物质液化法生物质液化法是将生物质加热到高温高压下，经过裂解反应，生成液态产品。
生物质液态产品是混合物，主要成分为烃类、酚类、杂环化合物和生物基单体等，可作为生物质液体燃料。
二、生物质能源的利用方法1.发电生物质发电是指利用生物质加热产生的蒸汽驱动涡轮发电机发电的一种方式。
生物质发电具有环保、可持续性等优点，可以利用废弃物资源进行发电，减少环境污染。
2.热能利用生物质热能利用包括生物质热能利用和生物质余热利用。
生物质热能利用主要是指利用生物质进行供热、供暖、蒸汽供应等领域。
生物质余热利用是指在生物质热能利用过程中产生的余热进行能量回收。
3.生物质液体燃料生物质液体燃料主要包括生物柴油和纯生物醇。
生物柴油是指将生物质油脂经过酯化和甲醇化等反应，制成一种可替代石油柴油的清洁燃料。
纯生物醇主要是指乙醇和丙醇，也是可替代石油化学产品的重要清洁能源。
三、生物质能源在环保领域的应用1.替代化石燃料生物质能源是一种可再生的、资源丰富的清洁能源，已成为替代化石燃料的重要手段。
生物质能源的利用不仅可以减少对化石燃料的依赖，还可以减轻环境污染。
生物质碳及水热炭化技术介绍
生物质碳及水热炭化技术介绍王艳秋【摘要】水热炭化是将废弃生物质在150℃—350℃密闭的水溶液中停留1h以上,是一种脱水脱羧的加速煤化过程,具有节省费用、效率高、能耗低等特点,其产物生物质炭是一种便于运输存储、热转化率高、污染小的优质材料,具有广泛的用途.【期刊名称】《江西化工》【年(卷),期】2018(000)001【总页数】2页(P154-155)【关键词】生物质炭;水热炭化【作者】王艳秋【作者单位】葫芦岛市环保局环境监测中心站,辽宁葫芦岛125000【正文语种】中文随着人口数量的快速增长以及农业生产现代化的不断推进和现代化工业的高速发展，人类对自然界存在的能源和资源的利用程度不断加深。
[1]同时，对畜禽产品需求量不断增加，致使畜禽养殖业特别是规模化养殖业迅猛发展，逐步趋向经济效益更显著的集约化、规模化和方向化的发展。
而随着畜禽养殖业的大力发展带来的环境问题更是不容小觑——已经成了中国农村面源污染的主要污染源，可谓是“畜产公害”。
解决畜禽废弃物的排放及其带来的环境问题，已经上升到关乎人类生存和发展以及新世纪中国生态农业发展的重大问题。
目前我国畜禽废弃物的污染与防治措施有用作肥料，畜禽废弃物资源化主要用来作肥料，畜禽粪便中含有丰富的植物所需的营养元素和有机物质，然而动物粪便并不适于直接用作肥料，在还田前要求作一定处理。
[2]目前主要方法有堆肥、生产复合肥料和干燥(主要用于鸡粪)；用作饲料、制沼气、用作培养料和用作燃料，其中堆肥是主要的处理措施。
在畜禽养殖过程中为了提高饲料的利用率、促进畜禽的生长，大量重金属制剂被用作生长促进剂添加到畜禽饲料中[3]。
这不仅会使畜禽产品中的重金属含量残留超标[4]，而且因动物的吸收率很低，畜禽粪便中重金属的含量随添加量的增加而增高[5]。
水热炭化是将废弃生物质在150℃—350℃密闭的水溶液中停留1h以上，是一种脱水脱羧的加速煤化过程[6]。
与传统裂解炭化技术相比，水热炭化具有显著的优势：(1)在处理含水量高的废弃生物质时无需干燥，节约了大量的预处理费用；(2)化学反应主要为脱水过程，废弃生物质中碳元素固定效率高；(3)反应条件温和，同时脱水脱羧的放热过程为反应提供了一部分能量，因此该技术能耗低；(4)水热炭化保留了大量废弃生物质中的氧、氮元素，炭化物表面含有丰富的含氧、含氮官能团，可应用于多种领域；(5)处理设备简单、操作方便、应用规模可调节性强。
水热碳化法制备生物炭过程
水热碳化法制备生物炭过程
水热碳化法是一种制备生物炭的方法，其过程是将生物质在高温高压的水环境中进行反应，最终得到生物炭产品。
首先，将生物质样品放入水中加热，温度通常在180℃左右，压力在10~20MPa之间。
这时，生物质开始进行水热碳化反应，将其转化为生物炭。
接着，将反应液沉淀，用离心机分离固体物质和液体部分。
固体部分即为生物炭，需要进行水洗和干燥处理，使其具有一定的物理强度和稳定性。
最后，生物炭制备完成，可以用于土壤改良、农业肥料、水处理等领域。
同时，水热碳化法制备生物炭的过程中，也可以产生有机酸等有机物质，可以回收利用。
总之，水热碳化法是一种有效的生物炭制备方法，具有简单、高效、无污染等优点，具有广泛的应用前景。
水热炭化工艺流程
英文回答：The hydrothermal carbonization process typically involves the following steps:1.Preparation of feedstock: The feedstock, which could be biomass materials such asagricultural waste, wood chips, or manure, is prepared and pretreated if necessary.2.Mixing and impregnation: The feedstock is mixed with water and possibly other additives toform a slurry. This slurry is then impregnated with heat and pressure to enhance the carbonization process.3.Hydrothermal carbonization: The slurry is then heated to high temperatures (typicallybetween 180°C and 250°C) under pressure, allowing for the conversion of organic matter into hydrochars, which are solid carbon-rich products.4.Solid-liquid separation: After carbonization, the solid hydrochars are separated from the liquidfraction, which can be further processed or disposed of.5.Drying and post-treatment: The solid hydrochars are then dried and possibly undergo furtherpost-treatment steps such as grinding, sieving, or activation.6.Product utilization: The final product, the hydrochar, can be used for various applications suchas soil amendment, fuel, or feedstock for further processing.中文回答：水热炭化工艺流程主要包括以下步骤：1.准备原料：准备生物质材料，如农业废弃物、木片或粪便等作为原料，并在必要时进行预处理。
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生物质水热煤化工艺
生物质水热煤化工艺是一种利用生物质作为原料，通过水热条
件下的化学反应将生物质转化为煤化工产品的技术过程。
这种工艺
可以被用于生产生物质煤、生物质炭、生物质沥青等产品。
在这个
过程中，生物质经过水热条件下的高温高压处理，发生裂解、聚合、重排等化学反应，最终形成类似于煤炭的煤化工产品。
生物质水热煤化工艺的优点之一是可以充分利用可再生资源，
有利于减少对化石燃料的依赖，有利于环境保护和可持续发展。
此外，生物质水热煤化工艺还可以实现生物质资源的高值利用，提高
生物质能源的利用效率。
然而，生物质水热煤化工艺也面临一些挑战。
首先，工艺条件
的控制和优化是一个复杂的问题，需要克服生物质成分复杂、反应
条件多变等难点。
其次，生物质水热煤化工艺的产品性能和稳定性
也需要进一步提升和验证。
此外，生物质水热煤化工艺的经济性和
可行性也需要进行深入的评估和研究。
总的来说，生物质水热煤化工艺作为一种新兴的生物质能源转
化技术，具有巨大的发展潜力，但在实际应用中仍然需要不断地进
行科学研究和工程实践，以解决相关的技术难题，推动该技术向产业化应用迈进。