NOVELTY - Internal circulation anti-blocking device in double-circulation anaerobic reactor comprises a programmable logic controller (PLC), an ultrasonic level gauge, an anti-blocking device main gas valve, a check valve and an electromagnetic valve, where the internal circulation anti-blocking device is located outside the double-circulation anaerobic reactor. The ultrasonic level gauge is located on the upper end of the gas-liquid separator of the double-circulation anaerobic reactor, and is connected to the PLC controller via a wire.    USE - Used as an inner circulation anti-blocking device in double-circulation anaerobic reactor.    ADVANTAGE - The device utilizes external circulating water to wash the blockage in internal circulation pipe and biogas lifting pipe, is economical and consumes less energy.    DETAILED DESCRIPTION - Internal circulation anti-blocking device in double-circulation anaerobic reactor comprises a programmable logic controller (PLC), an ultrasonic level gauge, an anti-blocking device main gas valve, a check valve and an electromagnetic valve, where the internal circulation anti-blocking device is located outside the double-circulation anaerobic reactor. The ultrasonic level gauge is located on the upper end of the gas-liquid separator of the double-circulation anaerobic reactor, and is connected to the PLC controller via a wire. The anti-blocking device main gas valve is in parallel with an external circulation water inlet control valve, and is connected to the external circulation system and the internal circulation anti-blocking device. The check valve and the magnetic valve are interconnected via a pipe. The anti-blocking device main gas valve is connected to a biogas lifting pipe and internal circulation pipe of the double-circulation anaerobic reactor.    DESCRIPTION OF DRAWING(S) - The drawing shows a schematic representation of the inner circulation anti-blocking device in double-circulation anaerobic reactor (Drawing includes non-English language text).