两种冷热电联供系统的热经济对比分析

Comparative thermoeconomic analysis of two combined cooling,heating and power systems

针对余热回收与能源利用,以固体氧化物燃料电池(SOFC)反应后的锅炉排气余热与液化天然气(LNG)冷能相结合,利用Aspen HYSYS建立了2个复合系统模拟流程,分别是卡琳娜(Kalina)-带回热朗肯循环(KC-RORC)冷热电联供(CCHP)系统与Kalina-带回热双朗肯循环(KC-RDORC)CCHP系统。通过一系列的分析与比较,结果表明:2个系统的蒸发器2热源进口温度、Kalina循环蒸发温度以及LNG膨胀压力在135—175℃、140—190℃以及2—8 kPa变化时,分别可获得最大净输出功211.73 kW和340.24 kW,最大热效率17.79%和23.61%,以及最大㶲效率37.32%和52.54%。KC-RDORC复合系统的平准化电费、折旧回收期分别比KC-RORC系统降低10.64%、16.93%,设备总投资、净权益提高了18.75%、39.39%。所以KC-RDORC复合系统在热力学及经济方面有更大的优势。

For waste heat recovery and energy utilization,combined with the waste heat of boiler exhaust after solid oxide fuel cell(SOFC)reaction and cold energy of liquefied natural gas(LNG),two composite system simulation processes were established using Aspen HYSYS,namely Kalina-regenerative Rankine cycle(KC-RORC)combined cooling,heating and power(CCHP)system and Kalina-regenerative double Rankine cycle(KC-RDORC)CCHP system,respectively.Through a series of analyses and comparisons,the results show that when the heat source inlet temperature of evaporator 2,Kalina cycle evaporation temperature and LNG expansion pressure of the two systems change at 135-175℃,140-190℃and 2-8 kPa,respectively,the maximum net output power is 211.73 kW and 340.24 kW,the maximum thermal efficiency is 17.79%and 23.61%,and the maximum efficiency is 37.32%and 52.54%.Compared with KC-RORC system,the levelized electricity cost and depreciation payback period of the KC-RDORC system are 10.64%and 16.93%lower,and the total equipment investment and net equity are 18.75%and 39.39%higher,respectively.Therefore,the KC-RDORC system has greater advantages in thermodynamics and economy.