NOVELTY - Device for producing biogas from organic solids by an anaerobic biological reaction, comprises reactor (1) designed as a container for receiving a mixture of liquid and solids, and a circulating pipe (2) that is open at both ends and is arranged in the center of the reactor, where a tubular nozzle (3) having a conically narrowed end extends in the operating position from above. The reactor is equipped with a pump (4) for feeding the mixture into the reactor through a pipe, and the mixture is moved in circulation formed by the circulating pipe and an annular space of the reactor.    USE - The device is useful for producing biogas from organic solids by an anaerobic biological reaction.    ADVANTAGE - The device: exhibits increased contact surface between the microorganisms and the solids, improved separation of the biogas; produces increased quantity of biogas; and makes use of agricultural products e.g. corn, grain and sugar beet, and organic waste e.g. sewage sludge and food waste.    DETAILED DESCRIPTION - Device for producing biogas from organic solids by an anaerobic biological reaction, comprises reactor (1) designed as a container for receiving a mixture of liquid and solids, and a circulating pipe (2) that is open at both ends and is arranged in the center of the reactor, where a tubular nozzle (3) having a conically narrowed end extends in the operating position from above. The reactor is equipped with a pump (4) for feeding the mixture into the reactor through a pipe, and the mixture is moved in a circulation formed by the circulating pipe and an annular space of the reactor surrounding the circulating pipe. The nozzle is designed without internals. The pipe extends at an upper end of the nozzle in operating position. At least one perforated sheet (7) is arranged in the annular space formed between the circulating pipe and the wall of the reactor, which extends at right angle to the axial direction of the circulating pipe, completely fills an intermediate space between the circulating pipe and the wall of the reactor, and additionally serves thorough mixing of the mixture.    DESCRIPTION OF DRAWING(S) - The figure shows a schematic sectional view of the device.    Reactor (1)    Circulating pipe (2)    Nozzle (3)    Pump (4)    Perforated sheet (7)