According to national standards, biogas digesters can be buried underground to build a three-in-one hydraulic biogas digester. Adopt automatic feeding and discharging installation mode, without management and never crusting. Thermal insulation biogas digester is a new patented product (ZL200720089403.3) which aims at the disadvantage that underground biogas digesters can not be used normally in winter. It adopts low-cost thermal insulation materials and production technology, and solves many technical problems existing in underground biogas digesters. It has the advantages of small size, beautiful appearance and convenient movement, and its biggest feature is that it can be installed and used without a pig. The production cost is the lowest (it can be produced with a brick-lined mold), the production process is simple (hand-made), the installation is labor-saving, and the standardization degree is high, so it is suitable for mass production and popularization. The tank can be processed into various shapes and sizes (4-30m3) as required. Can be sealed for more than half a year at a time, fed in stages and changed once every two years. Biogas residue is completely sterilized and is a "green biological fertilizer" for producing green food.
On a cloudy day without the sun, when the weather temperature is lower than 10℃, the thermal insulation technology that can only absorb heat but not dissipate heat must be adopted, otherwise it cannot be used normally.