Vapor heat exchanger system with water drainage function

The invention provides a water drainage system which can adjust condensation water at the U-type bottom of a vapor pipe according to vapor flow resistance of a vapor heat exchanger and improve heat exchange efficiency of the vapor heat exchanger on the condition that an automatic water drainage valve block is not additionally provided when the heat exchanger with vapor as a heat source is used and a U-type structure is inevitably formed due to structure limits of the heat exchanger, and particularly relates to a vapor heat exchanger system with a water drainage function. The system comprises components of a traditional vapor heat exchanger system and is further additionally provided with an automatic water drainage pipe for condensation water at the U-type bottom of the heat exchanger, and the automatic water drainage pipe can be used for discharging the condensation water at the U-type bottom of the heat exchanger.