US Patent 7258725 Gas supplying method and system

Gas supplying method and system in which effective component gas in exhaust gas can be separated and purified efficiently to be resupplied regardless of variation in the flow rate or composition of the exhaust gas and consumed gas can be replenished efficiently. In a method for collecting exhaust gas discharged from a gas using facility, separating/purifying effective component gas contained in the exhaust gas and supplying the effective component gas thus obtained to the gas using facility, the exhaust gas discharged from the gas using facility is added with a replenishing gas of the same components as the effective component gas before the effective component gas is separated and purified.