NOVELTY - Bio gas fermentation tank comprises a closed fermentation tank, the upper fermentation tank wall and tank shell respectively is set with biogas slurry inlet, slag arrange slag port and gas exhaust port, where the liquid feedstock is set with relative port of ferment tank wall and tank shell in supernatant and fermentation tank shell layer of the biogas slurry of the biogas slurry feedstock where the fermentation tank shell and biogas slurry and the supernatant layer are connected and is set up to make organic object to enter in biogas slurry feed port.    USE - The device is used as bio gas fermentation tank (claimed).    DETAILED DESCRIPTION - Bio gas fermentation tank comprises a closed fermentation tank, the upper fermentation tank wall and tank shell respectively is set with biogas slurry inlet, slag arrange slag port and gas exhaust port, where the liquid feedstock is set with relative port of ferment tank wall and tank shell in supernatant and fermentation tank shell layer of the biogas slurry of the biogas slurry feedstock where the fermentation tank shell and biogas slurry and the supernatant layer are connected and is set up to make organic object to enter in biogas slurry feed port such that the cooling gas cannot enter into the first sealing device in fermentation tank and shell, the organic matter via the first sealing device, feed inlet enter into fermentation tank in shell, the bio gas discharge port is set on tank wall of the fermentation tank shell upper part liquid level of biogas slurry, with the first control valve set up in exhaust port, the bio gas in the fermentation tank shell through gas exhaust port, the first control valve after discharging out fermentation tank shell, the precipitation slag arrange slag port is set with relative the fermentation tank wall and tank shell in precipitate layer and fermentation tank shell and biogas is on the upper part, arranging the slag and ferment tank shell and biogas precipitate layer are connected, the slag mouth in precipitation slag formed with can make the precipitate fermentation tank discharging shell, the gas cooling the outside world cannot enter into the second sealing device in fermentation tank and shell, the second sealing device and the second control valve are connected with the fermentation and precipitate in tank shell via precipitation slag arranging slag mouth, the second sealing device, the second control valve after discharging fermentation tank shell out, also equipped with can adjust liquid temperature with stirring and uniformly mixing the biogas liquid and heat stirring device, the stirring device is set with heat exchange in the active layer in the biogas slurry in delamination state and where in ferment tank shell, also set with driving heat exchange stirring device for slurry by stirring and driving device, the heat exchange stirring device can make active layer of biogas slurry and supernatant layer and scum layer mixing uniformly under driving of driving device on in fermentation tank shell outside.    DESCRIPTION OF DRAWING(S) - The diagram shows a schematic representation of Bio gas fermentation tank.