NOVELTY - Double-internal circulation anaerobic granular sludge biochemical reactor has a tower unit (100), a water distributor (200), a first grade biogas collecting device (310), a gas gathering pipe (410), a pulse device (411), a second grade biogas collecting device (320), a second circulation pipeline (420), and a gas-liquid separator (421).    USE - The double-internal circulation anaerobic granular sludge biochemical reactor is useful for producing biogas.    ADVANTAGE - The double-internal circulation anaerobic granular sludge biochemical reactor has strong convection in tower unit, fully mixes wastewater and granular sludge, enhances mass transferring effect of organic material, improves treating ability of reactor, and promotes yield of biogas.    DETAILED DESCRIPTION - Double-internal circulation anaerobic granular sludge biochemical reactor has a tower unit (100), a water distributor (200), a first grade biogas collecting device (310), a gas gathering pipe (410), a pulse device (411), a second grade biogas collecting device (320), a second circulation pipeline (420), and a gas-liquid separator (421). The bottom portion of the tower unit is provided with the water distributor. The upper portion of the water distributor is provided with the first grade biogas collecting device. The upper end outlet of the first grade biogas collecting device is provided with the gas gathering pipe. The inlet of the gas gathering pipe is connected to the upper outlet of the first grade biogas collecting device. The outlet of the gas gathering pipe is connected to the outer portion of the tower unit. The inlet of the gas gathering pipe is provided with the pulse device. The outer portion of the inlet of the gas gathering pipe is connected with the second grade biogas collecting device. The inner portion of the tower unit further comprises the second circulation pipeline. The inlet of the second circulation pipeline is connected in water at the bottom of the tower unit and the outlet of the second circulation pipeline is connected to the outer portion of the tower unit. The middle portion of the second circulation pipeline is provided with the gas-liquid separator.    DESCRIPTION OF DRAWING(S) - The drawing shows schematic view of double-internal circulation anaerobic granular sludge biochemical reactor.    Tower unit (100)    Water distributor (200)    First grade biogas collecting device (310)    Second grade biogas collecting device (320)    Gas gathering pipe (410)    Pulse device (411)    Second circulation pipeline (420)    Gas-liquid separator (421)