The company has several sets of liquid discharge pipeline, pump suction pipeline safety valve selection, in the actual operation process, there is a widespread overpressure unloading. At present, the operation technology of air separation is generally mature, and the operation standard of liquid gasification is the same. The problem reflected by the users does not exist in operation, but the safety valve always fails. The old air separation units used to have liquid oxygen and liquid argon pipeline, equipped with safety valves of liquid oxygen 0.22 MPA and liquid argon 0.28 MPA, are generally installed on the second floor platform, which is no problem. For safety reasons, there are safety valves between the two valves in the present liquid gasification system, which is much more than before. The recent operation of several sets of equipment is basically the same as before. Before the pump, the configuration of safety valve is 0.22MPA, because the configuration of storage tank is also 0.22MPA. In the actual operation process, the pressure and liquid level of the storage tank are not constant, and there is the possibility of overpressure. Therefore, if the take-off pressure is low, the fail is normal.
According to the investigation of most users, the safety valves replaced in the later stage, the conventional low-pressure air separation, and the safety valves from the suction pipe in front of the pump to the cold box are in the range of 0.35-0.4MPA, which is reasonable. The low pressure storage tank can also meet the requirements according to the full pressure of the argon tank of 19.5M and the pressure of several tens KPA. Besides, between the two valves, the pipeline pressure rating is about 40KG, the valve is generally 16KG, and it is not too much to set 5KG protection for the safety valve. As for the equipment, the equipment has its own protection, only considering the pipeline part. Now the general pump suction pressure is 0.05 ~ 0.8MPA, so it is unnecessary to set it very low, which brings trouble to the operation.
