Patent ID: 6290921
Filing Date: 2001-09-18
Classification: B01D,F23C,F23J

Abstract:
A method of binding pollutants in flue gas in one or more combustion plants, the method comprising the following steps:(a) combusting fuel in a furnace of the one or more combustion plants, resulting in the production of flue gas containing pollutants;(b) introducing at least one of calcium oxide, limestone and dolomite, into the furnace for binding pollutants in the flue gas in the furnace;(c) causing flue gas to flow through (i) a flue gas channel, (ii) a venturi contact reactor which is dimensioned so to provide a desired division of the moistened ash of step (e) into a portion entrained with the flue gas and another portion falling down into a retention tank provided in connection with the flue gas channel, and (iii) then through a dust separator, which separates ash containing unreacted calcium oxide from the flue gas;(d) conducting a portion of the ash separated from the flue gas in step (c) to a moistening device, which mixes water in an amount of up to 50% of the weight of the ash into the ash;(e) conducting ash moistened in step (d) to the contact reactor, to mix the moistened ash into the flue gas;(f) causing a first portion of the ash mixed into the flue gas in step (e) to be entrained with the flue gas to the dust separator thus binding pollutants in the flue gas;(g) causing a second portion of the ash mixed into the flue gas in step (e) to fall down into the retention tank for ash arranged below the contact reactor;(h) hydrating at least a portion of the calcium oxide in the ash to form calcium hydroxide in the retention tank;(i) causing the ash to dry out during the hydrating step (h); and(j) recycling at least a portion of the ash from the retention tank to at least one of the one or more combustion plants.