Storage tank of inner floating and top suspending central upper drainage device

The utility model relates to a tank with an inner floating roof for lighter hydrocarbon storage and transmission or methanol sewage treatment, in particular to a storage tank whose inner floating root is hung with a central upper discharge device. The utility model comprises a tank boy, an inner floating roof (1) in the tank body and a central discharge device. The utility model is characterized in that the lower portion of the inner floating roof is provided with a liquid collect chamber (2) communicated with the central discharge device, the liquid collect chamber (2) is provided with a liquid inlet (6) and a vent hole (5) around while the vent hole (5) is above the liquid inlet, the liquid collect chamber (2) is a pipe with a sealed round or square section, the lower end or side end of the liquid collect chamber is provided with an connector, while the upper end (2) is sealed with the lower surface of the inner floating roof (1). The storage tank with a central upper discharge device hung on the inner floating roof can confirm the normal operation of the central discharge device, reduce medium consumption and develop the mediums at any height.