NOVELTY - Stirring and heating biomass in an anaerobic fermentation tank, comprises separating oxygen from air, performing oxygen-enriched combustion of fuel by heating the oxygen-enriched water in the anaerobic fermentation tank to generate marsh gas in gas-liquid phase, and stirring the biomass in the fermentation tank.    USE - The method is useful for stirring and heating biomass in an anaerobic fermentation tank (claimed).    DETAILED DESCRIPTION - An INDEPENDENT CLAIM is included for the biomass anaerobic fermentation tank comprising a fermentation tank (18), a heating device, a gas-liquid two-phase jet device, and a gas separating device, where the gas-liquid phase jet flow device is set in the fermentation tank, the heating device is configured for heating a medium in the fermentation tank, the gas separating device is configured for separating the oxygen from and is connected with the heating device, a separated oxygen fuel mixing pipe and the heating device are configured for oxygen-enriched combustion, the heat is generated by the supply of water to the heating device, the gas-liquid two-phase jet device is configured for supplying water to the heating device, the fermentation tank medium contains flow of gas-liquid phase, the heating device comprises a hot water boiler, an oil tank and an oil burner, the oil tank is connected with the burner through an oil pump, the burner is connected with the gas separating device that is separated the oxygen through a fan, the fan is connected with an air inlet, air passes through the air inlet to the burner, the hot water boiler act as a heat source, the gas separation device comprises a first compressor (1), a first membrane separator (2) and an oxygen storage tank, the membrane separator is connected with the first compressor and is configured for separating oxygen, the oxygen storage tank has an oxygen outlet, the first compressor absorbs air and passes through the first membrane separator, the oxygen storage tank is connected with the fan and the burner that is connected with the air inlet, the gas separation device further comprises a second compressor (7), a second membrane separator (3) and methane storage tank, the second compressor includes an inlet, the fermentation tank, the methane storage chamber is connected with the air inlet of the second compressor, an air outlet is connected to the second membrane separator, the second membrane separator is configured for separating the fuel and carbon dioxide gas, the separated fuel is stored in the methane tank, the heating device is further provided with a gas burner, the methane storage tank and oxygen storage tank are connected with the gas burner that is connected with the air inlet and is configured for oxygen-enriched combustion of the separated methane fuel, the gas separation device is provided with a carbon dioxide storage tank (4) having an outlet and a blower that is connected with the gas-liquid phase jet device, the gas-liquid phase jet flow device receives carbon dioxide gas and water heated in the fermentation tank and comprises a nozzle, a nozzle supporting rod, a swing motor and a moving mechanism, the nozzle supporting rod is positioned along the fermentation tank in the height direction, an upper part of the gas-liquid two-phase jet device is provided with a moving guide groove, an end of the nozzle is set on the moving guide groove, the nozzle supporting rod is configured to form sliding fit connected with the nozzle, the hot water boiler is with a steam outlet and a steam inlet, the nozzle is provided with the fan, the steam outlet and a steam inlet are connected with the gas inlet, the swinging motor is connected with the nozzle supporting rod for swing periodically driving the nozzle rod about a certain angle, the moving mechanism is connected with the nozzle for driving the nozzle to periodically move up and down along the moving guide groove and comprises a driving motor, a steel wire rope and a winding device that is fixedly connected with the drive motor, the drive motor is configured for driving the winding device to rotate, the steel wire rope is wound on the winding device, and one end of the steel wire rope is connected with the nozzle to move up and down.    DESCRIPTION OF DRAWING(S) - The diagram shows a schematic view of a fermentation tank.    First compressor (1)    First membrane separator (2)    Second membrane separator (3)    Carbon dioxide storage tank (4)    Second compressor. (7)