DEHUMIDIFICATION SYSTEM FOR RAW GAS IN SEPARATION APPARATUS BY PRESSURE SWING ADSORPTION PROCESS

摘要

PURPOSE:To obtain a dry gas of low dew point and also to keep a high dehumidification performance even when an operation gas pressure is low without consuming a large amount of dry virgin gas for purging by introducing a desorbed off-gas out of an adsorption tower to outer sides of separation membranes. CONSTITUTION:Raw air is pressurized by a compressor 4 and sent to an adsorption tower 1 through an air supply piping 5 and a valve 8 after dehumidified by separation membranes 3. Nitrogen is adsorbed by the adsorption tower 1 and separated oxygen, which is not adsorbed, is sent to a product tank 17 through a valve 12. On the other hand, nitrogen adsorbed by the adsorption tower 2 in the previous process is discharged through the outer paths of the separation membranes 3 while reducing a pressure in the adsorption tower 2 to atmospheric pressure. A dry air of lower dew point is thus obtained, because the outer sides of the membranes 3 are purged by this discharge operation and the partial pressure of water vapor in the outer sides of the membranes 3 is lowered. Next, the operations of adsorption towers 1, 2 are changed over and the desorbed nitrogen from the adsorption tower 1 is introduced to the outer sides of the membranes 3 and purges them.