LNG冷能与中深层地热能驱动的发电系统性能分析与优化

Performance Analysis and Optimization of Power Generation System Driven by LNG Cold Energy and Medium-deep Geothermal Energy

结合LNG冷能和中深层地热能特点,根据梯级用能理论,构建LNG冷能与中深层地热能驱动的联合循环发电系统,系统主要由LNG直接膨胀部分、地热单级闪蒸循环及回热式有机朗肯循环三部分组成。基于Peng-Robinson状态方程,选用模拟软件HYSYS,对发电系统进行模拟计算,研究关键参数对系统热效率、?效率和平均能源成本的影响。结果表明,随着地热水蒸发压力的增大,循环热效率提升13.99%,?效率提升7.58%,平均能源成本减小2.81%;LNG气化压力的增大使得循环热效率提升9.39%,?效率提升3.13%,平均能源成本减小8.01%;天然气外输压力的增大使得热效率降低20.93%,?效率提升38.44%,平均能源成本增加25.21%。利用遗传算法对系统进行单目标优化,结果显示系统最大热效率为37.37%,最大?效率为53.92%,最低总成本率为0.782百万美元/a。

Combined with the characteristics of LNG cold energy and medium-deep geothermal energy,a combined cycle power generation system driven by LNG cold energy and medium-deep geothermal energy was constructed based on the theory of cascade energy utilization.The system mainly consists of LNG direct expansion,geothermal single-stage flash cycle and regenerative organic Rankine cycle.Based on Peng-Robinson equation of state,simulation software HYSYS was used to simulate the power generation system to study the impact of key parameters on the thermal efficiency,exergy efficiency and average energy cost of the system.The results showed that with the increase of the evaporation pressure of geothermal water,the cycle thermal efficiency increased by 13.99%,the exergy efficiency increased by 7.58%,and the average energy cost decreased by 2.81%.With the increase of LNG gasification pressure,the cycle thermal efficiency increased by9.39%,the exergy efficiency increased by 3.13%,and the average energy cost decreased by 8.01%.With the increase of the pressure of natural gas export,the thermal efficiency decreased by 20.93%,while the exergy efficiency increased by 38.44% and the average energy cost increased by 25.21%.Genetic algorithm was used for the single-objective optimization of the system,and the results showed that the maximum thermal efficiency of the system was 37.37%,the maximum exergy efficiency was 53.92% and the minimum total cost rate was US$ 0.782million/a.