Usually single-stage ejector compression ratio does not exceed 10, the working pressure is not less than lOkPa. So when the need for lower working pressure, then by two or more ejectors and condensers in series, called multi-stage jet pump. The role of the condenser is to condense the condensable steam in the mixture partially to eliminate the load of the lower ejector. The structure of the condenser are hybrid, surface and jet three forms. Condenser according to its injection pump system in the installation location, is divided into the front condenser, the middle condenser and the rear condenser. The front condenser is installed in front of the primary ejector inlet, primarily to reduce the load on the primary pump. Only when the pumping mixture contains a large amount of condensable steam, and the steam partial pressure stronger than the cooling water temperature corresponding to the saturated vapor pressure can only be used. Intermediate condenser installed in the middle of the multi-stage pump, the specific location should be depending on the mixture into the condenser steam partial pressure and cooling water temperature, and its role is to reduce the load on the lower pump. After the rear condenser is installed in the final stage ejector, mainly to eliminate the final ejector exhaust, noise, and sometimes used to recover the exhaust heat of the non-stage ejector.
