Method and apparatus for concentrating ozone gas

A method of concentrating ozone gas comprising:

• concentrating and purifying ozone gas, including:
• causing ozone gas contained in ozone-oxygen mixture gas to be selectively adsorbed to adsorbents which are filled in a non-cooled state in at least two adsorbing cylinders arranged parallel to one another;
• and desorbing the ozone gas from the adsorbents by subjecting a depressurizing process to each adsorbing cylinder during an ozone gas desorption operation;
• repeating an adsorption step and a desorption step alternately in the at least two adsorbing cylinders;
• and controlling the adsorbing cylinders, in such a way that one of the adsorbing cylinders is performing the adsorption step while another one of the adsorbing cylinders is performing the desorption step, wherein
• when the adsorption step of the ozone gas and the desorption step thereof are switched over, one of the adsorbing cylinders that has performed the adsorption step is made to communicate with another one of the adsorbing cylinders that has been at a stage of completing the desorption step, thereby equalizing internal pressures thereof, and subsequently, the one of the adsorbing cylinders that has been at an adsorption stage is made to communicate with decompression generation section, thereby desorbing the ozone gas from the adsorbents;
• termination timing of a pressure equalization step is controlled in such a way that the pressure equalization step is terminated at a stage where an internal pressure difference between respective ones of the adsorbing cylinders that have higher and lower internal pressures reaches 40% or less of the internal pressure difference therebetween at the beginning of the pressure equalization step;
• and
• a valve placed on an ozone gas inlet side of one of the adsorbing cylinders that has performed the adsorption step is closed while a valve placed on an outlet side thereof is opened, immediately before the pressure equalization step starts, thereby decreasing an internal pressure of the one of the adsorbing cylinders.