Cold belt open type heating methane tank device

The utility model relates to a biogas tank, in particular to an open temperature increasing biogas in a frigid zone. The utility model is characterized in that a piston cylinder is connected at the central opening on the arch-surface tank top (18), a piston (5) connected under a handle (4) is arranged in the piston cylinder (3), and a tank opening (9) is arranged on top of the handle (4); an intake hole (1) is positioned below a liquid level (10) and on top of the communicated opening (15) of a water pressure chamber and a fermentation chamber; at the side opposite to the intake hole (1) and under the liquid level (10), an automatic scum channel is formed by a scum pipe inlet extending to the bottom of the fermentation chamber (8) and an open scum hole (7) at the tank body (2); the periphery of the arch-surface tank top (18) is connected with the inner side of the tank body (2) to enclose the water pressure chamber (17); heater strips are arranged at the bottom of the tank body (2); and air holes (19) are arr