喷射式热泵在天然气冷热电三联供系统中的应用研究

Application of Steam Ejector Pump in CCHP Systems

天然气冷热电三联供系统中普遍采用减温减压器将高品位的蒸汽节流降温以供各类用户,节流降温过程伴随不可逆能量损失,导致高品位蒸汽做功能力下降。本研究将喷射式热泵引入天然气冷热电三联供系统,利用高品位蒸汽引射低品位蒸汽,排挤高品位蒸汽返回汽轮机做功,在不改造汽轮机通流部分的前提下提高了系统的经济性。对某三联供系统的分析计算表明,其全厂发电效率、联供系统效率、系统供热能力均有大幅度提高,并能够在不扩建机组的情况下,满足工业园区热负荷增长的需求。研究获得的喷射式热泵的优化设计原则和变工况调节方法,对喷射式热泵技术的研究和推广应用具有重要意义。

Generally, in combined cold, heat and power （CCHP） systems, desuperheaters are used to obtain the low grade steam. However, during the pressure and temperature reduction process, irreversible energy losses are caused, lowering the steam working capability. In this study, the steam ejector pump is introduced into the CCHP system to lower the steam grade by virtue of high grade steam entrainment, forcing the high grade steam to return to the steam turbine to convert into power. As a result, the economic efficiency of the CCHP system is improved without changing the flow path of the steam turbines. The calculation and analysis indicate that when applying the steam ejector pump in the system, the generation and system efficiencies and the maximum heat supply capacity of the CCHP system increase significantly and they can meet the heat demand increase. In addition, the optimization design principles and off-design adjustment method of the steam ejector pump are valuable for the study and application of steam ejector pumps.