基于燃机余热和地热能的联合发电系统优化设计及热力性能分析

Optimal Design and Thermal Performance Analysis of Combined Power Generation System Based on Gas Turbine Waste Heat and Geothermal Energy

设计了一种超临界二氧化碳(S-CO_(2))再压缩系统与地热双闪蒸系统相结合的新型燃机余热利用联合发电系统。基于所建联合系统参数优化模型,应用遗传算法计算分析了联合系统内部参数和边界参数对最大输出功和燃机余热利用率的影响。结果表明:通过系统参数优化,联合系统实现了余热在2个子系统中的合理分配,加深了燃机余热的进一步利用;当一级闪蒸压力取99.89 kPa、二级闪蒸压力取29.4 kPa、S-CO_(2)质量流量取22.68 kg/s、分流比取0.3085时,联合系统最大净输出功达到6.402 MW,对应余热效率为67.9%;当一级闪蒸压力在90~115 kPa、二级闪蒸压力在25~35 kPa时,联合系统均可实现较高的净输出功,与最佳值的相对偏差在0.8%以内;随着S-CO_(2)流量或分流比逐渐增大,联合系统的净输出功均呈现先增大后减小的规律;联合系统的最大净输出功随S-CO_(2)透平进口压力的增大而增加,随S-CO_(2)透平出口压力和预冷器出口温度的增大而减小。

A new type of combined power generation system was designed,which integrated the S-CO_(2) recompression system and the geothermal double flash system.The effects of internal and boundary parameters on the net maximum output power and waste heat utilization rate were calculated and analyzed using genetic algorithm based on the parameter optimization model of the combined system.Results show that optimizing system parameters can achieve a reasonable distribution of waste heat in the two subsystems and cascade utilization of gas turbine waste heat.When the primary flash pressure is 99.89 kPa,the secondary flash pressure is 29.4 kPa,the S-CO_(2) flow rate is 22.68 kg/s,and the split ratio is 0.3085,the maximum net output power of the combined system is 6.402 MW,the corresponding waste heat efficiency is 67.9%.When the primary flash pressure is 90-115 kPa and the secondary flash pressure is 25-35 kPa,the combined system can achieve high net output power,with a relative deviation from the optimal value within 0.8%.The net output power of the combined system shows a pattern of increasing first and then decreasing as the S-CO_(2) mass flow rate or split ratio increases.The maximum net output power of the combined system increases with the increase of S-CO_(2) turbine inlet pressure and decreases with the increase of S-CO_(2) turbine outlet pressure and precooler outlet temperature.