基于LNG冷能利用的燃气轮机/超临界二氧化碳循环关键参数经济性研究

Economic study on key parameters of gas turbine/supercritical carbon dioxide cycle based on LNG cold energy utilization

超临界二氧化碳(S-CO_(2))循环具有循环效率高、设备尺寸小、运输安装方便、易于达到临界点等优势。考虑到液化天然气(LNG)具有的巨大冷能,不仅可以作为冷却剂应用于联合循环系统,且换热后的天然气既可以作为联合循环的燃料输入,剩余部分又可供给城市用户。故提出了一种基于LNG冷能利用的燃气轮机/S-CO_(2)联合循环系统,选择合适成本公式对循环发电系统的投资成本、运行收益以及回收周期进行计算分析;对联合循环系统中一些关键参数的变化(如最高温度、最高压力、最低温度、最低压力和分流比)对S-CO_(2)循环的发电特性、经济性影响进行研究。结果表明:每个单参数的增大都会使设备投资成本呈现先增大后减小的趋势,但是发电量的大小对收益的影响占主导地位;以收益作为衡量标准,最高温度越高越好,最低温度越低越好,其他参数下均存在最佳值使收益达到最大;对关键参数以累计收益最大为优化目标进行遗传算法优化,优化后的回收周期为5.86年,20年累计收益为22.87亿元。

The supercritical carbon dioxide cycle has many advantages,such as high cycle efficiency,small equipment size,convenient transportation and installation,and easy to reach the critical point.Considering the huge cold energy of LNG,it can not only be used as coolant in the combined cycle system,but also the natural gas after heat transfer can be used as fuel input in the combined cycle,and the rest can be supplied to urban users.A gas turbine/supercritical carbon dioxide combined cycle system based on the utilization of LNG cold energy is proposed in this paper.Select the appropriate cost formula to calculate and analyze the investment cost,operating income and recovery cycle of the circulating power generation system in detail.The influence of some key parameters(such as maximum temperature,maximum pressure,minimum temperature,minimum pressure and shunt ratio)on the power generation characteristics and economy of the supercritical carbon dioxide cycle in the combined cycle system was studied.The results show that with the increase of each single parameter,the cost of equipment investment will first increase and then decrease,but the effect of power generation on income is dominant.Taking the yield as the measurement standard,the higher the maximum temperature,the better,the lower the minimum temperature,the better.Under other parameters,there are optimal values to maximize the yield.The key parameters were optimized by genetic algorithm to maximize the cumulative income.After optimization,the recovery cycle was 5.86 years,and the cumulative income(20 years)was 2.287 billion yuan.