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为回收利用对流热采油页岩过程中产生的低温余热蒸汽,提出并设计有机朗肯循环(ORC)系统进行热力发电。在特定余热蒸汽参数条件下,基于R245fa循环工质,编制计算程序模拟分析了ORC系统变工况参数对该系统热效率及输出功率的影响规律。数值模拟结果表明:设定汽轮机背压为0.25MPa时,工质最高蒸发压力为2.566MPa,在此范围内,系统热效率随蒸发压力升高单调增加,增幅减缓;取蒸发器出口温度85℃时,对于不同的蒸发压力系统允许运行工质流量范围不同,在同一蒸发压力下,由于热源限制导致系统热效率并未随工质流量增加显著提高,但可得到更多输出净功;蒸发压力为1.5 MPa时,随余热排放温度的降低,系统输出净功显著提高;随汽轮机背压的降低,系统热效率得到明显改善,但汽轮机背压的降低增加了工质冷凝的困难,合适的背压值取0.2MPa。
In order to recover and utilize low-temperature waste heat steam generated during convective thermal recovery of oil shale, organic Rankine cycle (ORC) system was proposed and designed for thermal power generation. Under the conditions of specific residual heat steam parameters, based on R245fa circulating working fluid, the calculation program was simulated to analyze the influence of ORC system parameters on the thermal efficiency and output power of the system. The numerical simulation results show that the maximum evaporation pressure of working fluid is 2.566MPa when the turbine back pressure is 0.25MPa. Within this range, the thermal efficiency of the system monotonically increases with the increase of evaporation pressure, and the increase slows down. When the outlet temperature of the evaporator is 85 ℃ , For different evaporation pressure system allows the working fluid flow range is different, under the same evaporation pressure, due to heat source constraints lead to thermal efficiency of the system did not significantly increase with the increase of the feed rate, but can get more output net work; evaporation pressure of 1.5 MPa, with the decrease of waste heat temperature, the output net power of the system increases significantly. With the reduction of steam turbine back pressure, the thermal efficiency of the system is obviously improved. However, the reduction of turbine back pressure increases the difficulty of refrigerant condensing. 0.2MPa.