【作者】 周响球；

【导师】 杨晨；

【作者基本信息】 重庆大学 ， 动力工程及工程热物理， 2008， 硕士

【摘要】 经济发展使得人类对化石燃料的需求量的不断增加,导致二氧化碳(CO2)的排放量逐年提高,造成越来越严重的地球温升问题。温室效应是由于以CO2为代表的温室气体的大量排放造成的,化石燃料燃烧产生的CO2占人类活动引起的CO2排放量的80%,其中电厂烟道气CO2排放量30%,因此电厂烟道气脱CO2是削减温室效应的关键。化学吸收法因其工艺简单、技术较为成熟得到了广泛的利用,其中,有机胺吸收法以其吸收速率快、吸收效率高等优点在近几十年得到了广泛的研究和应用,发展迅速。针对燃煤电厂烟道气CO2分压较低,使用MEA的化学吸收对于脱除烟道气物流中的二氧化碳是一项可利用的技术。但是,这套吸收装置的操作费用特别是再生塔再沸器所需能耗很大,难以大规模的商业应用。本文运用化工系统工程的相关理论,为降低CO2捕获系统运行成本,针对如何降低吸收剂再生能耗的问题进行了研究。介绍了使用单乙醇胺(MEA)吸收430MW燃煤电厂烟道气中CO2的工艺流程,利用Aspen Plus中基于流率的非平衡模型—RateFrac建立了CO2捕获系统的过程模型。基于MEA脱碳系统的物性特点,选择了适当的热力学物性方法(ELECNRTL)和物性方程(NTRL),采用流程模型分解的方法,利用Aspen Plus化工系统模拟软件对脱碳系统进行模拟计算。为实现脱碳系统的CO2排放目标,考察并研究了吸收塔塔板数、再生塔塔板数和贫MEA负荷等参数对吸收剂再生能耗的影响。利用了Aspen Plus中的设计规定和灵敏度分析函数对脱碳系统进行了参数优化,从而获得了该系统的一些过程参数与设计生产的基础数据。在此基础上,提出了一种设有旁路系统的改进CO2捕获系统,在保证相同CO2捕获率的前提下,能够减少进入吸收塔的烟气流量,从而有效降低能耗。应用本工艺系统模型能够对MEA捕获CO2系统进行静态计算及分析研究,为吸收塔和再生塔的设计、运行、工艺及运行参数优化提供理论依据。本课题得到的结论有一定的理论意义和实际应用价值。更多还原

【Abstract】 As the development of mankind economy, the demand of energy supply expanded. A large amount of carbon dioxide emited to atmosphere from combustion of fossil fuels causes severe environment damage and greenhouse effect. The emission of greenhouse gases induces greenhouse effect among which CO2 is typical. The amount of CO2 emission from fossil fuels accounts for 80 percent of all the emission caused by human activity, and the amount of CO2 from power plants is 30 percent. So the removal of CO2 from flue gas of power plants is the sticking point on greenhouse effect mitigation.Method of chemical absorption is using most widely process because of its mature and availability. Among the methods, the amine absorption has good qualities of faster absorption rate, higher efficiency and so on, so it has been studied and made a rapid progress in these years. According to the less presstrue CO2 in coal-fired flue gas, the monoethanolamine (MEA) absorption of CO2 from coal-derived flue gases on the scale proposed above is technologically feasible. But MEA absorption is an energy intensive process and especially requires large quantities of low-pressure steam.In order to reduce the CO2 capture system operation cost, we use the theories of process systems engineering in the simulation and study on how to reduce the energy requirement for solvent regeneration was provided. A CO2 removal process for post-combustion CO2 capture from a 500 MW coal-fired power plant, based on absorption/desorption process with MEA solutions, was described. Then a process simulation model had been developed by using Aspen Plus with the RateFrac unit operation module for the absorber and stripper.According to the physical properties of the carbon dioxide removal system, the proper thermodynamic property calculation method (ELECNRTL) and the thermodynamic equation (NRTL) are chosen, the method of decomposing the flow sheet is adopted, to the system simulation and calculation on the steady state process simulation software Aspen Plus.To achieve the requirement of carbon dioxide removal system, this simulation and optimization aimed to reduce the energy consumed, by investigating the effects of the number of absorber trays, the number of stripper strays, lean MEA loading. The sensitivity analysis and design regulation function in the Aspen Plus software has been used to determine the optimizing parameters of the carbon dioxide removal system. The detailed process parameters of this system, the fundamental for the design and the production, are get hold of. An advanced amine CO2 removal system was put forward. The reduced recovery rates can be achieved by two methods which respectively are achieved by treating only part of the flue gas stream in the absorber and bypassing the remainder of the flue gas stream directly to the stack. The bypassing method allows the energy requirement of amine regeneration system to be smaller and less.This system model is applicabled to the basic study and to steady performance study for the system of CO2 absorbed by MEA, and can provide an academic reference for the design、operation、technics、and parameter optimization study for the system of absorber and stripper. It is testified that what we did have theory and applied price.更多还原