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以300MW机组煤粉炉省煤器为例,对锅炉常压空气燃烧、常压富氧燃烧和5种不同增压(6MPa)富氧燃烧方案下的锅炉对流受热面尺寸、烟气流量、烟气侧传热系数和压降等参数进行了计算和分析,根据基于经济性分析的单位换热量换热器总费用最小的原则确定省煤器的最佳设计结构.结果表明:与常压空气燃烧相比,常压富氧燃烧下烟气体积流量减小了28.5%,对流传热系数减小了11.5%;增压富氧燃烧下的烟气体积流量减小了98.82%,随着烟气流速的增大,受热面面积减小,烟气侧传热系数和压降增大;最佳方案中的烟气流速为1.54m/s时,单位换热量换热器总费用约为常压空气燃烧下的60%,烟气侧压降为582.65Pa,烟道截面积仅为常压空气燃烧下的7.8%.
Taking the pulverized coal economizer of 300MW unit as an example, the effects of atmospheric pressure air combustion, atmospheric oxygen enrichment combustion and five kinds of pressurized (6MPa) oxy-fuel combustion schemes on boiler convection heating surface size, flue gas flow, Gas-side heat transfer coefficient and pressure drop were calculated and analyzed, and the optimal design of economizer was determined according to the principle that the total cost of unit heat exchanger was the lowest based on economic analysis.The results showed that: Compared with air combustion, the volume flow of flue gas under atmospheric pressure oxygen-rich combustion decreased by 28.5% and the convective heat transfer coefficient decreased by 11.5%, while the volumetric flow of flue gas under pressurized oxygen-enriched combustion decreased by 98.82% Flue gas velocity increases, the heating surface area decreases, the flue gas side heat transfer coefficient and pressure drop increase; the best scheme flue gas flow rate of 1.54m / s, the unit heat exchanger heat exchanger total cost of about 60% under normal pressure air combustion, the pressure drop on the flue gas side is 582.65Pa, and the cross-sectional area of the flue gas is only 7.8% under normal pressure air combustion.