Marsh gas fermentation tank with gas-collecting hood for realizing unpowered automatic stirring

The utility model relates to a fermentation tank, particularly to a marsh gas fermentation tank which realizes unpowered, automatic stirring by utilizing a gas collecting hood. The marsh gas fermentation tank provided by the utility model comprises a tank wall; and the gas collecting hood is arranged at the upper part of the tank wall and is fixed by a bracket on the tank wall. The utility model has the following advantages and effects: the addition of the gas collecting hood into the fermentation tank can enable marsh gas produced during the process of gas production to be concentrated, to overflow from the gas collecting hood and meanwhile to carry fermentation liquid out, thereby realizing the automatic stirring during the fermentation process; based on the principle of the natural ascending of gas in the gas collecting hood, the marsh gas produced by the fermentation passes through the gas collecting hood mounted at the upper part of the fermentation tank which then discharge the marsh gas out from the ve