| 摘要 |
PURPOSE:To effectively remove NOx in waste gas from steam-reforming furnace or combustor, for which the decrease of NOx only by controlling combustion is unattainable, by using a small amount of catalyst by a method in which a catalyst layer is provided in a waste gas duct in which the temperature of the waste gas is within a specific range and a reducing agent is sprayed to the upstream of the waste gas near the catalyst layer. CONSTITUTION:Waste gas from the combustion of a radiation type short flame burner 2 in a steam reforming furnace is directed from a waste gas outlet 4 into a waste gas duct 5 and then heat-exchanged with a heat exchanger in which a steam heater 6, a waste heat recovery boiler 7, a preheater 8 for gas to be treated, and a preheater 9 for supply water are orderly arranged. In this case, a catalyst layer 10 is provided inside the preheater 8 for the waste gas to be treated, branched into plural heating pipe groups, where the temperature distribution in the duct 5 goes around the range 300 to 400 deg.C. Then a reducing agent, e.g., NH3, etc., is sprayed in place close to the catalyst layer 10 and where the reducing agent can be uniformly dispersed, e.g., in the upstream side of the heating pipe groups of the preheater 8 for waste gas to be treated, located on the upstream side of the catalyst layer 10, from a reducing agent sprayer 11 provided there. |
