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Show 4. Selective Catalytic NOx Reduction System 4-1) Principle of Selective Catalytic NOx Reduction System The Selective Catalytic NOx Reduction System is the one in which a reducing agent, such as ammonia gas, etc., is added before the reactor that is filled with catalyst and NOx is decomposed to harmless N2 and H20 and removed while NOx passes through the catalyst. The quantity of the reducing agent is controlled automatically so that the denitrification ratio or outlet NOx concentration become as designated from the NOx concentration before and after the reactor. Ammonia gas or ammonia water is used as a reducing agent. When using the Selective Catalytic NOx Reduction System, by determining required quantity of catalyst from inlet NOx concentration, outlet NOx concentration, gas temperature, etc., a very high denitration can be achieved and it is possible to make outlet NOx concentration to below 10 ppm. 4-2) Example of plant The combustion exhaust gas, after corning out of the incinerator, its heat is recovered in the boiler and at the same time cooled, and after dust removal through the electric precipitator (EP) discharged through the smoke stack using the induced draft fan (IDF) • • Incinerator completed in ... December 1974 • Selective Catalytic NOx Reduction System completed •.. March 1988 • Type of furnace ••. NKK - V¢LUND type double waste gas flow - 6 - |
