燃机余热利用的超临界二氧化碳循环发电系统

Supercritical Carbon Dioxide Brayton Cycle Power System on the Heat Recovery for Gas Turbine

结合超临界二氧化碳物性分析、工质在主设备工作过程,讨论了主设备中工质的基本状态。根据燃机余热烟气特点,建立了余热利用的超临界二氧化碳循环发电计算程序,分析了简单循环、再压缩循环、复合简单循环、复合再压缩-简单循环4种循环布置下的系统稳态参数、效率以及净输出功。研究表明:透平入口工质压力越高,透平出口工质的温度越低,工质携带热量的利用越充分;压缩机入口温度应尽量接近临界点(31.1℃)、压力需稍高于临界点(7.4 MPa),可保证压缩机出口温度较低、工作状态稳定、单位工质流量的功耗小。随热源最低温度的下降,系统所获得净功以及实际效率均能得到一定的提升,通过叠加方式实现的烟气分级利用可以显著提高燃机余热利用的超临界二氧化碳循环系统效率和净功。

Discussed working fluid basic state during main equipment processing based on the physical properties and the processing of main equipment. Built the calculation program of supereritieal carbon dioxide cycle on heat reeovery referring to the flue-gas physical properties of gas turbine. The system state parameters, efficiency and net power were analyzed as followings： the simple Brayton cycle, the recompress cycle, the combined simple - simple cycle and the combined reeompress-simple cycle. Then, for turbines, the higher pressure of inlet working fluid and the lower temperature of outlet working fluid, the more heat which the working fluid can carry. For compressors, the inlet temperature of working fluid should close to the supereritieal point and the pressure should be slightly higher than the supereritieal point, which can ensure the cold temperature of outlet, the stable working state, and the minimum power consumption. For different types of cycle, with the decreasing of the lowest temperature of cycle, the network of system and the system efficiency increase. The classification of gas utilization by combined cycles could highly increase the efficiency and network of heat recovery system for gas turbines.