NOVELTY - A system for producing agricultural mechanical power fuel by methanation of biogas comprises a loading device, a fermentation tank, an air storage tank, a desulfuration device, a gas compressor, a dehydration device, a decarburization tower, a decarburization liquid regeneration tower, a dehydration agent regeneration device, a hot water furnace, and a heat exchanger.    USE - The system is useful for producing agricultural mechanical power fuel by methanation of biogas (claimed).    ADVANTAGE - The system combines the methane production, storage, compression, and purification together; thus, the produced methane can be conveniently applied to an agricultural vehicle or an agricultural machine tool.    DETAILED DESCRIPTION - A system for producing agricultural mechanical power fuel by methanation of biogas comprises a loading device, a fermentation tank, an air storage tank, a desulfuration device, a gas compressor, a dehydration device, a decarburization tower, a decarburization liquid regeneration tower, a dehydration agent regeneration device, a hot water furnace, and a heat exchanger; where a water outlet of the loading device is connected with a water inlet on the upper part of the fermentation tank; an air outlet on the top part of the fermentation tank is connected with an air inlet in the middle of the air storage tank via the methane pipeline; a liquid outlet on the bottom of the fermentation tank is connected with a liquid inlet of the loading device via a methane return pipeline; a gas outlet on the top part of the gas storage tank is connected with a desulfuration upward pipeline; the desulfuration device comprises first and second desulfuration tanks connected in parallel; the first and second desulfuration gas inlets are respectively installed on the top parts of the first and second desulfuration tanks while the first and second desulfuration gas outlets are respectively mounted on the bottom parts; the first and second desulfuration gas inlets are respectively connected with the desulfuration upward pipeline via the first and second gas inlet pipelines; the first and second desulfuration gas outlets are respectively connected with a desulfuration downward pipeline via the first and second desulfuration gas outlet pipelines; the first desulfuration gas outlet is connected with the second desulfuration gas inlet via a first by-pass pipeline; the second desulfuration gas outlet is connected with the first desulfuration air inlet via a second by-pass pipeline; the desulfuration downward pipeline is connected with a gas inlet of the gas compressor; the desulfuration downward pipeline is also connected with the fuel inlet of the hot water furnace via a third by-pass pipeline; a gas outlet of the gas compressor is connected with the decarburization downward pipeline via a methane pressure bearing pipeline; the decarburization downward pipeline is connected with the gas inlet of the decarburization tower; the gas outlet of the decarburization tower is connected with the decarburization upward pipeline; the decarburization upward pipe is connected with the dehydration upward pipeline; the dehydration device consists of first and second dehydration tanks connected in parallel; the first and second dehydration gas inlets are respectively equipped on the top parts of the first and second dehydration tanks while the first and second dehydration gas outlets are respectively arranged on the bottom parts; the first and second dehydration gas inlets are respectively connected with the dehydration upward pipeline via the first and second dehydration gas inlet pipelines; the first and second dehydration gas outlets are respectively connected with the dehydration downward pipeline via the first and second dehydration gas outlet pipelines; the dehydration agent generation device comprises an air cooler, a gas and water separator, a circulation draught fan, and an electric heater; a gas outlet of the air cooler is connected with a gas inlet of the gas and water separator; a gas outlet of the gas and water separator is connected with the circulation pipeline; the circulation pipeline is connected with the regeneration gas upward pipeline; the circulation draught fan is installed on the circulation draught fan; the electric heater is mounted on the regeneration gas upward pipeline; the first and second dehydration gas inlets are respectively connected with the regeneration gas downward pipeline via fourth and fifth by-pass pipelines; the first and second dehydration gas outlets are respectively connected with the regeneration gas upward pipeline via sixth and seventh by-pass pipelines; one way of the regeneration gas downward pipeline is connected with the gas inlet of the air cooler; another way is connected with the tail gas pipeline; one more way is connected with the return pipeline; the tail gas pipeline is connected with the fuel inlet of the hot water furnace; the return pipeline is connected with the gas inlet of the gas compressor; the hot water outlet of the hot water furnace is connected with a pipe stroke entrance of the heat exchanger via the hot water pipeline while a pipe stroke exit is connected with a return water port of the hot water furnace; a shell stroke exit of the heat exchanger is connected with the material inlet of the fermentation tank via a second material liquid pipeline; a shell stroke entrance of the heat exchanger is connected with a material outlet of the loading device via a third material liquid pipeline; a barren liquor inlet of the decarburization tower is connected with a barren liquor outlet of the decarburization liquid regeneration tower; a barren liquor pump is installed on a barren liquor pipeline; and a rich liquor inlet of the decarburization liquid regeneration tower is connected with a rich liquor outlet of the decarburization tower via a rich liquor pipeline.    DESCRIPTION OF DRAWING(S) - The drawing shows a schematic diagram of the system for producing agricultural mechanical power fuel by methanation of biogas.