美国代写毕业论文：生物质气化模型。由于生物质形式不方便以及其固有的笨重性，在目前状态下对其的利用将引起人们的关注(Loha et al.， 2014)。与化石燃料相比，生物质的能量密度非常低，使用生物质相对于化石燃料的优势将受到如何转移和处理这种质量的限制。“因此，处理、储存和运输生物质的原始形式比传统燃料更加昂贵。因此，要充分利用生物质，就必须改善其性能，提高其处理、储存和运输能力”。为了便于处理，固体生物质被转化为气态或液态。生化和热化学转化是这种转化背后的化学反应。这种热化学转化形式被称为生物质气化。气化模型是一个复杂的化学反应运行在一个设置独特的发展为目的。文献综述的目的是关注不同研究人员在流化床气化过程中使用的不同模型和用于预测系统中某些复杂活动的不同模拟模型的细节。

在生物质气化过程中，原料被转换成一些方便和有用的东西，比如气态燃料。在存在气化剂的情况下，使用特定的化学物质可以将其还原到那种状态。一些气化剂是空气或氧气和茎。气化炉所实现的是惯例的原料，以一种形式，其中氢碳H/C的比例是高得多，因此，它将改进燃烧范围。有不同的方法来实现这是通过热解，氧化和还原。干燥也是达到这个目的的一种方法。气化炉的使用温度低于150度，因此与高温器相比是一个方便的系统，高温器的使用温度在150到700摄氏度之间。氧化只在这个温度下发生，原料中的水分现在完全蒸发，使它成为方便使用的挥发性化合物。气化过程中释放出的挥发性气体有氢气、一氧化碳气体和焦油。热解被认为是更方便的选择。而在还原反应中，根据不同的反应，如水气反应或甲烷化反应的转换反应，可燃气体及其不同的比例会有所不同。每一种反应都会产生一种输出气体，因此，性质会因反应的选择而不同。

气化炉由两个容器组成，其中有固体颗粒床材料。气化炉要么自动运行的热或allo热。气化炉有许多类型和变化可以追溯到操作参数，结构和气体的组成。针对目前的工程情况，选择流化床气化炉FBG。例如，在上吸式固定床类型或流化床气化炉的情况下，可以确定，由于使用热解产品，甲烷水平和焦油含量可能很高。因此，在这种使用中非常需要气体清洗。一方面，当更清洁的气体是需要然后下吸固定床气化炉是利用。同样，在均匀的温度分布是需要的，它是常用的利用流化床气化炉。它提高了碳转换效率，有利于生产高价值的天然气。与任何形式的气化炉使用，FBG方法遭受一些轻微的缺点，如焦油的形成，必须处理，团聚在床和更多。更多的缺点将在后面使用现有的二手文献来讨论。

在FBG的气化过程中，存在着许多相互关联的步骤和反应，可以确定在FBG的设置中，反应物和产物也会在不同的反应中发挥典型作用。因此，光纤光栅被认为是一个非常复杂的化学系统。要使化学系统有效地使用它，需要更好地了解构成系统的模型和作为系统一部分的子模型。研究综述分析将非常有助于理解不同的操作参数和/或模型将如何影响FBG工作产生的气体质量。

定的一些反应类别有煤焦燃烧、煤焦气化、均相挥发反应、焦油反应等等。isC CO2 + O2🡪char燃烧反应。假设参考温度为298kJ/nol时的反应热为-394，该反应为完全燃烧反应。

其他反应在char燃烧是0.5 C + O2🡪CO粒子燃烧反应的热量反应温度在-111。char气化反应温度-75 C + H2🡪CH4,甲烷化反应。第二个字符气化反应是C +二氧化碳🡪2CO加热温度为173,是Boudouard反应。最后一个char气化反应如果C + H2O🡪CO + H2是蒸汽气化反应。同样，也有均相挥发反应，如甲烷重整反应、水气转移、一氧化碳氧化和氢氧化，还有焦油反应，如蒸汽重整反应、部分氧化等。

In the biomass gasification, the feedstock is converted into something convenient and useful, like a gaseous fuel. It is reduced to that state using specific chemicals in the presence of a gasifying agent. Some of the gasifying agents are that of air or oxygen, and stem. What the gasifier achieves is the convention of the feedstock to a form where hydrogen to carbon H/C ration is much higher, and hence, it would be improved combustion range. There are different ways to achieve this which are by means of pyrolysis, oxidation and reduction. Drying is also a way to achieve this. The gasifier will make use of a temperature that is less than 150 degrees and is hence a convenient system compared to the pyrolizer, which makes use of a temperature of around 150 to anywhere around 700 degrees Celsius. Oxidation will occur at this temperature only and the moisture in the feedstock is now completely evaporated making it a convenient volatile compound for use. Volatile vapors released in gasification are hydrogen, carbon monoxide gases and tar. Pyrolysis is considered a more convenient option. In the case of the reduction reactions, however, the combustible gases and their various percentages would differ according to the respective reaction, such as the water gas reaction or the shift conversion reaction of the methanation reaction. Each of the reaction produces a form of output gas, and hence, it can be argued that properties differ as per the reaction selection.

A gasifier is composed of two vessels where a solid particle bed material is present. A gasifier is either operated auto thermally or allo thermally. Gasifiers are of many types and the variations can be traced to the operating parameter, the structure and the composition of the gas. The use of the fluidized bed gasifier FBG is selected for some pertinent reasons with respect to the project at hand. For instance, in the case of the updraft fixed bed type or the Fluidized bed gasifiers, it is identified that the methane levels and tar content could be high because of the use of pyrolysis products. Gas cleaning is hence highly required in such usage. On the one hand, when much cleaner gas is required then the downdraft fixed bed gasifier is made use of. Similarly, where uniform temperature distribution is required, it is common to make use of the fluid bed gasifier. It gives improved carbon conversion efficiency that is better for production of high value gas. As with any form of gasifier use, the FBG method suffers some slight drawbacks like the tar formation which has to be handled, the agglomeration in the bed and more. More on the drawbacks will be discussed with the use of existing secondary literature later.

In the gasification process in the FBG, many interrelated steps and reactions exists, and it is identified that in the setup of the FBG, the reactant and the product would quintessentially play in different reactions, too. Hence, the FBG is considered as a very complex chemical system. Making that chemical system efficient for it use would require better knowledge on the models that make the system and the sub models that are used as part of the system. The research review analysis will be very helpful for understanding how different operating parameters and/or models will impact on the gas quality that is being produced as a resultant of the working of the FBG.

Some categories of reactions identified are the char combustion, the char gasification, the homogenous volatile reactions, the tar reactions and more. The char combustion reaction isC+O2🡪 CO2. The heat of reaction at a reference temperature assumed at 298kJ/nol is -394 and the reaction is considered as complete combustion reaction.

The other reaction under char combustion is C+0.5 O2🡪CO which is a particle combustion reaction at a heat of reaction temperature at -111. The char gasification reactions are C+H2🡪CH4 with temperature at -75, which is a methanation reaction. The second char gasification reaction is C+ CO2🡪2CO with a heat temperature of 173 and is a Boudouard reactions. The final char gasification reaction if C+H2O🡪CO+H2 are a steam gasification reaction. Similarly, there are homogenous volatile reactions such as methane reforming reaction, the water gas shift, the carbon monoxide oxidation and the hydrogen oxidation, and then there are tar reactions such as steam reforming reaction, the partial oxidation and more.

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