锅炉余热利用系统不同集成方式的热经济学分析

发布时间：2018-09-09 20:27

【摘要】：随着能源和环境问题日益严峻,燃煤机组面临着巨大的节能减排压力。对燃煤电厂锅炉尾部烟气余热进行回收利用,不仅可以提高电厂经济性,节约煤耗,同时能减轻对环境的污染。对烟气余热利用系统进行合理评价,是实现机组节能降耗和优化的有效方法。本文应用热经济学结构理论的方法,以某350MW机组为基础,利用STAR-90仿真系统,对余热利用与空气加热系统(Case 2)、二级烟气余热和水回收系统(Case3)、二级MGGH余热利用系统(Case 4)三种不同集成方式的燃煤电厂锅炉排烟余热利用系统进行热经济学成本和环境成本的计算,并与原机组(Case 1)进行对比分析,对四种不同的集成方式进行(火用)分析和热经济学分析,同时计算环境损害成本,考虑了烟气中2SO、XNO、2CO和烟尘对环境的影响。同时对余热利用系统在变负荷工况下进行(火用)成本对比分析,综合考虑各种集成方式的优劣。结果表明,Case 2、Case 3的产品单位(火用)成本和热经济学成本都要低于Case 1原机组,表明其具有良好的节能效果;Case 2的节能性最优,而Case 4为了更深度的利用烟气余热,控制余热利用系统各组件的换热面积,导致不可逆损失增大,热经济学成本偏高。利用相对成本差、比(火用)损等热经济学指标来综合衡量四种集成方式的优劣。同时Case 4的环境成本低于其他三种集成方式,表明其具有最优的环保效果。系统变负荷工况下的动态分析,可以指导系统的运行和优化。
[Abstract]:With the increasingly serious energy and environmental problems, coal-fired units are facing enormous pressure of energy saving and emission reduction. The recovery and utilization of flue gas waste heat from the boiler tail of coal-fired power plant can not only improve the economy of the power plant, save the coal consumption, but also reduce the pollution to the environment. It is an effective method to realize energy saving and consumption reduction and optimization for flue gas waste heat utilization system. In this paper, the method of thermoeconomics structure theory is applied, based on a certain 350MW unit, the STAR-90 simulation system is used. The thermoeconomic cost and cost of waste heat utilization system of coal-fired power plant boiler exhaust gas (Case _ 2), secondary flue gas waste heat and water recovery system (Case3) and secondary MGGH waste heat utilization system (Case _ 4) are analyzed. Calculation of environmental costs, Compared with the original unit (Case 1), the exergy analysis and thermoeconomic analysis of four different integrated methods were carried out, and the environmental damage cost was calculated, and the influence of 2SOXNO2CO and soot on the environment was considered. At the same time, the exergy cost of the waste heat utilization system under variable load condition is compared and analyzed, and the advantages and disadvantages of various integration methods are considered synthetically. The results show that the unit exergy cost and thermoeconomic cost of Case _ 2 / Case _ 3 are lower than those of Case _ 1 unit, which indicates that it has the best energy-saving effect and Case _ 4 can utilize the waste heat of flue gas in order to make better use of the waste heat of flue gas. Controlling the heat transfer area of each component of the waste heat utilization system leads to the increase of irreversible loss and the higher cost of thermoeconomics. The relative cost difference and exergy loss are used to evaluate the advantages and disadvantages of the four integration methods. At the same time, the environmental cost of Case 4 is lower than that of the other three integration modes, which indicates that Case 4 has the best environmental protection effect. The dynamic analysis of the system under variable load conditions can guide the operation and optimization of the system.
【学位授予单位】：华北电力大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TK115;TM621.2

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