NOVELTY - The digester comprises a biomass pool main body provided with a fermentation chamber (1), a gas storage chamber (2) and a water storage ring (3). The main body is provided with a water pressure air-feeding device, which is connected with a water pressure chamber, a water pressure pipe and a feeding port. The main body comprises a feeding device (4) and an automatic discharging device. The feeding device is provided with a feeding main pipe (5) and a return pipe, which are vertically combined together to form a gap.    USE - The digester is useful for slag-feed.    ADVANTAGE - The digester is simple in structure, safe and cost-effective, and has better air-tightness effect, and is capable of automatically digesting the slag-feed.    DETAILED DESCRIPTION - DETAILED DESCRIPTION -The pool comprises a biomass pool main body provided with a fermentation chamber (1), a gas storage chamber (2) and a water storage ring (3). The main body is provided with a water pressure air-feeding device, which is connected with a water pressure chamber, a water pressure pipe and a feeding port. The main body comprises a feeding device (4) and an automatic discharging device. The feeding device is provided with a feeding main pipe (5) and a return pipe, which are vertically combined together to form a gap. A liquid return slot is connected with the feeding device. An upper end of the feeding device is connected with the feeding port. A lower end of the feeding device is connected with a fermentation chamber. The automatic discharging device comprises a discharging pipe and a slag discharging unit. The discharging pipe is arranged on a bottom part of the slag discharging unit. A lower end of the slag discharging unit is inserted into a bottom part of the fermentation chamber. The water pressure pipe is connected with a bottom part of the water pressure chamber. A lower end of the fermentation chamber is arranged below the water pressure chamber.    DESCRIPTION OF DRAWING(S) - The figure shows a schematic view of a digester for discharging biomass.    Fermentation chamber (1)    Gas storage chamber (2)    Water storage ring (3)    Feeding device (4)    Feeding main pipe. (5)