Abstract: A flammable gas concentration system comprises concentrating means for acquiring at least a portion of the product gas, concentrating the flammable gas included in the acquired product gas, and generating a high-concentration gas; and mixing means for acquiring the raw gas and the high-concentration gas generated by the concentrating means, mixing the acquired high-concentration gas and the raw gas, and generating the product gas.

Abstract: A flammable gas concentration device comprises an adsorption tower filled by an adsorbent for adsorbing a flammable gas; feeding means for feeding a raw gas containing air and a flammable gas to the adsorption tower via a feeding path and discharging an exhaust gas in the raw gas which has not been adsorbed to the adsorbent to an outside of the adsorption tower via a discharge path; collection means for reducing a pressure in the adsorption tower lower than an atmospheric pressure, and desorbing the flammable gas adsorbed by the adsorbent and collecting the flammable gas through a collection path; and control means for sequentially executing a flammable gas adsorption step of feeding the raw gas to the adsorption tower and discharging the exhaust gas from the adsorption tower by the feeding mean, and a flammable gas desorption step of collecting the flammable gas desorbed by the collection means.