Keita Kawamura

Pilot plant experience in electron-beam treatment of iron-ore sintering flue gas and its application to coal boiler flue gas cleanup

Abstract The peresent development status of the electron-beam flue gas treatment process, which is a dry process capable of removing SOx and NOx simultaneously, is described. The most advanced demonstration of this process was accomplished with a pilot plant in Japan where the maximum gas flow rate of 10,000 Nm 3 /h of an iron-ore sintering machine flue gas was successfully treated. The byproduct produced in this process is collected as a dry powder which is a mixture of ammonia sulfate and ammonium nitrate and is salable as a fertilizer or a fertilizer component. A preliminary economic projection showed that this process costs less than the lime scrubber which removes SOx but does not remove NOx. Tests using simulated coal combustion gases suggest that this process will be applicable to coal-fired boiler flue gas treatment as well. However, test on actual coal-fired flue gases are still required for commercial application decisions. A process development unit program consisting of the design, construction and testing of actual coal-fired power station flue gases is underway in the U.S.A. The design and engineering of the test plant is far advanced and the construction phase will be launched in the very near future.

Pilot plant experiment of NOx and SO2 removal from exhaust gases by electron beam irradiation

Abstract The effects of a small quantity of ammonia (NH3) added to exhaust gases containing nitrogen oxides (NOx) and sulfur dioxide (SO2), the characteristics of the NH3 added to the gases to facilitate the removal of NOx and SO2 when the gases were irradiated by electron beam were studied. The experiment was conducted in a pilot plant (capacity: 1000 Nm3/h) for one and a half years. The Phenol Disulfonic Acid Method and the Arsenazo-III Method were used for NOx and SOx determination in the irradiated gases respectively. The NH3 was added at either the reactor inlet or outlet and greatly improved the efficiency of NOx and SO2 removal, and made the by-products stable. NOx and SO2 removal were shown to be solely determined by total dose regardless of dose rate and residence time. A maximum efficiency of 90% was accomplished both in NOx and SO2 removals. Under the most economical conditions, 80% of NOx and 75% of SO2 were simultaneously removed with 80 ppm of NH3 exhausted to the atmosphere. The amounts of nitrogen and sulfur in the gas before and after irradiation satisfactory balance under this condition. The collected products in the electrostatic precipitator are largely composed of a mixture of ammonium sulfate (NH4)2SO4 and ammonium nitrate sulfate (NH4)2SO4▿2NH4NO3 plus (NH4)2SO4▿3NH4NO3.