Falling film evaporator

The invention provides a falling film evaporator. The falling film evaporator comprises an evaporator box body, an inner heat exchange tube and a gas-liquid separation box, wherein a heat exchange tube group formed by a plurality of inner heat exchange tubes is arranged in the evaporator box body; the gas-liquid separation box is adjacently arranged on the upper side of the heat exchange tube group; an upper cover plate of the gas-liquid separation box is provided with exhaust holes and a refrigerant inlet pipe; the refrigerant inlet pipe is used for inflow of a refrigerant; the exhaust holes are used for discharging the gaseous refrigerant in the gas-liquid separation box; a plurality of openings are formed in a bottom plate of the gas-liquid separation box; and the refrigerant in the gas-liquid separation box flows to the heat exchange tube group through the openings so as to carry out evaporation heat exchange. Due to the fact that the inner heat exchange tubes are arranged in a staggered mode in the verti