Abstract: 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.

Key words: steam ejector pump, CCHP, optimal design, off-design performance