PSA SWITCHOVER VALVE SYSTEM

PURPOSE:To simplify a valve system of PSA gas purifier, by providing a three or more way valve which, by switching action, can be connected with only one of a raw gas supply pipe, a washed gas supply pipe and a deodorized gas pull-out pipe connected to an inlet of an absorbing tower. CONSTITUTION:The raw gas is sent from a pipe 7 to an absorbing tower 6A through a four-way valve 21 and the exhaust gas resulting from the adsorption of a target gas is delivered to a pipe 19 through a four-way valve 20. In the subsequent washing process, the target gas is sent from a blower 11 to the adsorbing tower 6A through pipes 13 and 10 and the four-way valve 21 to force the off-gas out of the tower and said gas is sent from a pipe 20 to a pipe 7 through the four-way valve 21. In a detaching process, the pressure of the adsorbing tower 6A is reduced by a vacuum pump 15 and the detached gas is sent from the four-way valve 21 to a gas holder 12. In a pressure raising process, the washed exhaust gas is sent from an adsorbing tower 6C to the adsorbing tower 6A through pipes 7 and 9 and the four-way valve 21 for a rise in the pressure. The use of such four-way valve prevents the inclusion in a product gas of the other gases in the event of valve malfunctions.