are allowed to communicate to each other on product discharge sides and on raw material supply sides respectively in the pressure equalization step, to recover the product gas under {TAIL ~ gradual increase} of {HEAD ~ gas flow rate} on the raw material supply side and also to evacuate the adsorption column having completed the adsoroption step 
are allowed to communicate to each other on product discharge sides and on raw material supply sides respectively in the pressure equalization step , to recover the product gas under { TAIL ~ gradual increase } of { HEAD ~ gas flow rate } on the raw material supply side and also to evacuate the adsorption column having completed the adsoroption step
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