NOVELTY - A system for producing agricultural machine power fuel by methane methanation comprises a feeding device, a fermentation tank, a gas storage tank, a desulfuration device, a gas compressor, a dehydration device, a decarburizing tower, a decarburizing liquid regeneration tower, a dehydrating agent regeneration device, a hot water boiler, and a heat exchanger.    USE - The system is useful for producing agricultural machine power fuel by methane methanation (claimed).    ADVANTAGE - The system integrates methane production, storage, compression and purification; thus, the methane becomes the gas fuel which can be directly applied to agricultural vehicle and agricultural tool.    DETAILED DESCRIPTION - A system for producing agricultural machine power fuel by methane methanation comprises a feeding device, a fermentation tank, a gas storage tank, a desulfuration device, a gas compressor, a dehydration device, a decarburizing tower, a decarburizing liquid regeneration tower, a dehydrating agent regeneration device, a hot water boiler, and a heat exchanger; where a discharge orifice of the feeding device is connected with the feeding orifice in the upper part of the fermentation tank through a first material liquid pipeline; an air outlet in the top part of the fermentation tank is connected with an air inlet in the middle part of the gas storage tank through a methane pipeline; the liquid outlet in the bottom part of the fermentation tank communicates with the liquid inlet of the feeding device through a methane liquid reflux pipeline; the air outlet in the top part of the gas storage tank is connected with a desulfuration upstream pipeline; the desulfuration device is formed by connecting the first and second desulfuration tanks in parallel; the top parts of the first and second desulfuration tanks are set with the first and second desulfuration air inlets; the bottom parts of the first and second desulfuration tanks are set with the first and second desulfuration air outlets; the first and second desulfuration air inlets are connected with the desulfuration upstream pipeline through the first and second desulfuration air inlet pipelines; the firs and second desulfuration air outlets are connected with the desulfuration downstream pipeline through the first and second desulfuration air outlet pipes; the first desulfuration air outlet communicates with the second desulfuration air inlet through the first bypass pipeline; the second desulfuration air outlet communicates with the first desulfuration air inlet through the second bypass pipeline; the desulfuration downstream pipeline is connected with the air inlet of the gas compressor; the desulfuration downstream pipeline is further connected with a fuel gas inlet of the hot water boiler through the third bypass pipeline; the air outlet of the gas compressor is connected with the decarburizing downstream pipeline through the methane bearing pipeline; the decarburizing downstream pipeline is connected with the air inlet of the decarburizing tower; the air outlet of the decarburizing is connected with the decarburizing upstream pipeline; the decarburizing upstream pipeline is connected with the dehydration upstream pipeline; the dehydration device is formed by connecting the first and second dehydration tanks in parallel; the top parts of the first and second dehydration tanks are set with the first and second dehydration air inlets; the bottom parts of the first and second dehydration tanks are set with the first and second dehydration air outlets; the first and second dehydration air inlets are connected with the dehydration upstream pipeline through the first and second dehydration air inlet pipelines; the first and second dehydration air outlets are connected with the dehydration downstream pipeline through the first and second dehydration air outlet pipelines; the dehydrating agent regeneration device comprises an air cooler, a gas water separator, a circulatory fan, and an electric heater; the air outlet of the air cooler communicates with the air inlet of the gas water separator; the air outlet of the gas water separator is connected with the circulatory pipeline that is connected with the regeneration gas upstream pipeline; the circulatory fan is arranged on the circulatory pipeline; the electric heater is arranged on the regeneration gas upstream pipeline; the first and second dehydration air inlets are connected with the regeneration gas downstream pipeline through the fourth and fifth bypass pipelines; the first and second dehydration air outlets are connected with the regeneration gas upstream pipelines through the sixth and seventh bypass pipelines; one path of the regeneration gas downstream pipeline communicates with the air inlet of the air cooler while the other path communicates with the tail gas pipeline and another path communicates with the reflux pipeline; the tail gas pipeline communicates with the fuel gas inlet of the hot water boiler; the reflux pipeline communicates with the air inlet of the gas compressor; the hot water outlet of the hot water boiler communicates with the pipe pass inlet of the heat exchanger through the hot water pipeline; the pipe pass outlet of the heat exchanger communicates with the water return opening of the hot water boiler through the water return pipeline; the shell pass outlet of the heat exchanger communicates with the feeding orifice of the fermentation tank through the second material liquid pipeline; the shell pass inlet of the heat exchanger communicates with the discharge orifice of the feeding device through the third material liquid pipeline; a barren liquid inlet of decarburizing tower communicates with the barren liquid outlet of the decarburizing liquid regeneration tower through the barren liquid pipeline; the barren liquid pipeline is set with a barren liquid pump; and the rich liquid inlet of the decarburizing liquid regeneration tower communicates with the rich liquid outlet of the decarburizing tower through the rich liquid pipeline.    DESCRIPTION OF DRAWING(S) - The drawing shows a schematic diagram of the system for producing agricultural machine power fuel by methane methanation.