The invention discloses a floating cover type dry 
fermentation biogas digester device. The outer side of a sealed water tank is provided with a 
thermal insulation layer; the sealed water tank is positioned on the periphery of a dry 
fermentation tank; a sealed 
water layer is arranged between the sealed water tank and the dry 
fermentation tank; a gas storage floating cover is positioned between thesealed water tank and the dry fermentation tank; a gas-guide 
pipe is arranged in the dry fermentation tank; the lower part of one side of the dry fermentation tank is provided with a 
discharge port and a tapping control valve; the lower part of the gas storage floating cover is provided with a lower guide 
branch wheel and a pressure-relief vent; the gas storage floating cover is also provided with a feed port, a viewing port, a 
biogas pressure gauge, a lifting ring, a primary desulfurizer and an escape 
pipe; an upper guide support wheel is arranged above the sealed water tank; the bottom in the dry fermentation tank is provided with a drain 
pipe which is connected with a stirrer in the gas storage floating cover through a circulating 
mud pump and a hose; and a water outlet pipe is connected with a steam boiler through the circulating 
mud pump. The floating cover type dry fermentation 
biogas digester device can control the 
gas transmission pressure by using the floating cover, can stirfermentation raw materials in operation by using the circulating 
mud pump and a biogas 
slurry stirrer, can be used all the year around, and is simple to construct.