An efficient solar-aided waste heat recovery system based on steam ejector and WTA pre-drying in solar/lignite hybrid power plants

摘要

An efficient solar-aided waste heat recovery system based on steam ejector and WTA pre-drying was proposed. In the proposed system, solar energy collected by parabolic trough collector is used to generate a little high-grade steam, inducing steam waste heat in steam ejector and producing large amount of medium-grade drying steam. By absorbing waste heat in steam ejector and integrating with coal pre-drying, the solar energy could be considered amplified in the steam ejector and converted into the dried coal's heating value. The results reveal that, for a typical 1000 MW lignite-fired power plant, 46.6 MW_(th) of steam waste heat could be recovered efficiently by collecting 21.6 MW_(th), of solar energy. The proposed system could produce 36.2 MW_e of additional power with 1.62％ of thermal efficiency increase. The cost of solar generated electricity of the proposed system is 0.028 USD/kWh, which is significantly lower than that of the conventional parabolic trough concentrating solar plants and solar-aided power generation system. The off-design performance reveals that the proposed system could solve the fluctuation of solar energy by dried coal storage.