OCR Text |
Show 3. Noncatalytic NOx Reduction System 3-1) Principle of Noncatalytic NOx Reduction System The noncatalytic NOx Reduction System which reducing agents, such as ammonia gas, ammonia water, etc. are blown into the high temperature combustion gas removes NOx by decomposing it into harmless N2 and H20. (NOx reduction reaction mechanism) Fig. 3-1 shows the basic flow of the noncatalytic NOx Reduction System using ammonia water. The ammonia water (25% concentration) is atomized by compressed air through a dual fluid nozzle and sprayed in the mixing chamber of incinerator. Although this example uses ammonia water as reducing agent the system will be the same basically except the supplying system of reducing agent, when liquid ammonia, urea, etc. are used. 3-2) Operating data of actual plant (l)NOx Concentration The results obtained from the Noncatalytic NOx Reduction system at a MWI plant is shown in Fig 3-2. This plant is 100 ton/24hx2 furnaces. Fig. 3-2 shows ammonia concentration, NOx concentration, etc. at the E.S.P outlet under operating the automatic control system. It can be seen that unreacted ammonia is only several ppm with no white smoke being visible. - 4 - |