Abstract: Taking the principles in API 521 as the guiding principles and based on engineering experience, this paper analyzes various working conditions that may cause overpressure in the ethylene-propylene-diene monomer (EPDM) polymerization reactor, such as fire, blocked outlet, control valve failure, chemical reaction, hydraulic expansion, and utilities failure. It focuses on the discussion of overpressure caused by thermal expansion of the liquid under external fire conditions and overpressure caused by reaction heat when chemical reaction is out of control. The paper calculates the required discharge capacityof safety valve under each working condition. The results show that the discharge capacity of safety valve is the largest under the condition of chemical reaction, 〖JP2〗reaching 47 520 kg/h, and the required discharge area of the〖JP〗 safety valve calculated according to the maximum discharge capacityis 415 mm2.

Key words: safety valve, discharge capacity, working condition analysis, thermal expansion