地热和生物质燃气联合发电系统建模与热力性能分析

Modeling and Thermal Performance Analysis of Geothermal and Biomass Gas Hybrid Power Generation System

针对中低温地热能电站发电效率低等缺陷,提出一种中低温地热和生物质燃气联合发电系统,采用热量大、温度低的地热能蒸发动力循环工质,温度高、热量少的生物质厌氧消化产气过热工质,初步选用氨为循环工质,建立系统热力性能分析模型,分析变工况特性下系统的循环热效率、生物质能利用分数和能-电转换效率,依据系统组成型式,建立地热能与生物质燃气联合发电系统成本计算模型,结果表明:工质过热度从0℃提高到220℃时,生物质能利用分数从0%增加到38.60%,能-电转换效率从5.84%提高到23.85%,LEC成本由0.105 5$/k Wh降低到0.070 7$/k Wh。结果可为中低温地热与生物质燃气联合发电系统的设计和性能评估提供理论依据。

A novel low-medium temperature geothermal and biomass gas hybrid power generation system is proposed for solve the disfigurement of low power generation efficiency of geothermal power plant. The geothermal energy with large heat but low temperature is used to evaporate the power cycle working fluid, moreover the production gas of biomass anaerobic digestion with high temperature but low heat is applied to superheat working fluid. Ammonia is preliminary selected as power cycle working medium. A thermodynamic cycle performance analysis model is established to analysis the cycle thermal efficiency, biomass fraction and energyelectricity conversion efficiency （eece） under off-design condition. The calculation model of levelized electricity cost （LEC） for the hybrid power generation system is set up based on the composition and structure. The calculation results show that the ammonia superheat is increased from 0℃ to 220 ℃, the biomass fraction will rise to 38.60% , and eece will improved from 5.84% to 23.85%. However, these improvements make the LEC of the hybrid generation system reduce from 0. 1055 $/kWh to 0.0707 $/kWh. The results provide a theoretical evidence for the system design and performance evaluation of the hybrid power generation system.