Abstract: Based on FDS, the diffusion process of biogas result from the leakage in anaerobic reactors has been studied, and three typical scenarios of biogas leakage in an anaerobic reactor were simulated including the breakage at the pipe joints, the breakage at the conduction pipe valve and the methane gas breaking through the water seal. Results showed that when the pipe joint or the valve of the conduction pipe are broken, the risk range is about 5 m downwind from the leak. But when the biogas breaks through the water seal, the risk range is more than 60 m downwind from the leak. So the risk of the biogas breaking through the water seal is the greatest. The methane after the leakage will spread downwind. But when encountering obstacles, methane will also accumulate in the nest wind position. When large area leakage happens like the biogas breaking through the water seal, the warning of the fixed stake gas alarm is very important.

Key words: anaerobic reactor, biogas leakage, methane concentration, simulation study