燃煤锅炉烟气余热回收系统的性能分析
发布时间：2018-09-11 17:40
【摘要】：中国的燃煤电厂在提供电能的同时消耗了大量的煤炭资源,电站锅炉作为电厂的主要设备之一,其效率会影响电厂整体的经济性,降低锅炉热损失能有效地提高锅炉效率,而排烟热损失占锅炉热损失的比重最大,因此通过余热回收系统来回收烟气余热是重要的节能措施。以国内某680MW超临界机组为例,针对低温省煤器与回热系统不同的集成方式,建立了串联、单级并联、跨级并联以及串并联混合6种集成方案,并得到了最优的集成方案;基于FLUENT软件研究了氟塑料光管低温省煤器的流动换热特性,并分析了管束排列方式、管间节距以及管排数对流动换热特性的影响,得到了不同情况下的传热和阻力特性,并将模拟值与准则式中的经验计算值进行比较,验证了模拟的正确性;根据最优的集成方案,在数值模拟的基础上,对低温省煤器从结构型式、管内外介质的流速、总传热系数以及压降损失等方面进行了设计,并且进行了经济性分析。结果表明,当低温省煤器跨级并联于6号低压加热器和7号低压加热器之间,在进出口水温分别为53.37℃和120.50℃,进出口烟温分别为143℃和85℃时,煤耗率降低值最大,节能效果最好。增设低温省煤器后,汽轮机抽汽量减少,供电煤耗降低,综合煤耗率降低了3.942g/(kW·h),回收了烟气余热量57.09MW,热耗率降低了102.27kJ/(kW·h),机组热经济性相对提高了1.36%,机组年节约煤量9650吨,年节煤收益为482.5万元。
[Abstract]:Coal-fired power plants in China consume a large amount of coal resources while providing electricity. As one of the main equipment in power plants, the efficiency of coal-fired power plants will affect the overall economy of power plants, and reduce the boiler heat loss can effectively improve the efficiency of the boiler. The heat loss of exhaust gas accounts for the largest proportion of boiler heat loss, so it is an important energy saving measure to recover flue gas waste heat through waste heat recovery system. Taking a 680MW supercritical unit as an example, six kinds of integration schemes of series, single stage parallel, cross stage parallel and series-parallel connection are established for different integration modes of low temperature economizer and regenerative system, and the optimal integration scheme is obtained. Based on FLUENT software, the flow heat transfer characteristics of low temperature economizer for fluoroplastic smooth tube are studied, and the effects of tube bundle arrangement, pipe pitch and tube arrangement on flow heat transfer characteristics are analyzed, and the heat transfer and resistance characteristics under different conditions are obtained. The correctness of the simulation is verified by comparing the simulated value with the empirical calculation value in the criterion formula, and according to the optimal integration scheme, on the basis of numerical simulation, the structure type, the velocity of medium inside and outside the tube of the cryogenic economizer, the flow rate of the medium inside and outside the tube are analyzed. The total heat transfer coefficient and pressure drop loss are designed, and the economic analysis is carried out. The results show that when the cross stage of the cryogenic economizer is parallel between the No. 6 low-pressure heater and the No. 7 low-pressure heater, when the inlet and outlet water temperatures are 53.37 鈩，
本文编号：2237398
[Abstract]:Coal-fired power plants in China consume a large amount of coal resources while providing electricity. As one of the main equipment in power plants, the efficiency of coal-fired power plants will affect the overall economy of power plants, and reduce the boiler heat loss can effectively improve the efficiency of the boiler. The heat loss of exhaust gas accounts for the largest proportion of boiler heat loss, so it is an important energy saving measure to recover flue gas waste heat through waste heat recovery system. Taking a 680MW supercritical unit as an example, six kinds of integration schemes of series, single stage parallel, cross stage parallel and series-parallel connection are established for different integration modes of low temperature economizer and regenerative system, and the optimal integration scheme is obtained. Based on FLUENT software, the flow heat transfer characteristics of low temperature economizer for fluoroplastic smooth tube are studied, and the effects of tube bundle arrangement, pipe pitch and tube arrangement on flow heat transfer characteristics are analyzed, and the heat transfer and resistance characteristics under different conditions are obtained. The correctness of the simulation is verified by comparing the simulated value with the empirical calculation value in the criterion formula, and according to the optimal integration scheme, on the basis of numerical simulation, the structure type, the velocity of medium inside and outside the tube of the cryogenic economizer, the flow rate of the medium inside and outside the tube are analyzed. The total heat transfer coefficient and pressure drop loss are designed, and the economic analysis is carried out. The results show that when the cross stage of the cryogenic economizer is parallel between the No. 6 low-pressure heater and the No. 7 low-pressure heater, when the inlet and outlet water temperatures are 53.37 鈩，
本文编号：2237398
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