AbstractEnvironmental pollution is one of the most important problems in present-day society. Governments and international organizations try to mitigate this problem by enforcing strict laws concerning the emission of certain pollutants. This process is especially rapidly applied concerning air pollution. In the past, the main focus was placed on the regulation of the energy sector and of land-based transportation emissions, as they produce the vast majority of pollutants. Today, the emphasis is shifted toward marine-based transportation, as it is anticipated that after the year 2020, the emission from sea-based sources (with respect to sulfur and nitrogen oxides) will exceed the land-based emission. One of the technologies that have been successfully implemented in industries to decrease the level of air pollution caused by NOx and SOx is electron beam flue gas treatment. This review shows the chemical principles of this method as well as the chemical engineering issues and its development and modifications to suit the changing needs of industries worldwide.
A bench-scale test (800 Nm3/h) for electron beam treatment of flue gas was conducted. It was concluded that the method is favourable for treatment of flue gas with a high SO2 concentration (5,500 ppm) at low electron beam irradiation (5 kGy). Results are consistent with the claim that SOx is removed from flue gas by the reaction of SOx with ammonia, and the intermediate salts formed are oxidised by radicals to sulphate salts consisting mainly of ammonium sulphate (a N-fertiliser). A typical flue gas desulphurization (FGD) method such as the wet limestone process cannot remove NOx and SO3 effectively (Ando, 1990), but the electron beam process removes SO2, SO3 and NOx simultaneously without generating waste water and CO2.
Peabody Coal Company, under contract to the National Center for Air Pollution Control, has investigated sulfur-dioxide removal from a pilot moving grate furnace stack gas by the addition of calcium bearing dry additives to the flue gas and to coal before burning. Effects of additive feed rate, residence time, temperature, and particle size on sulfur-dioxide removal were studied, and calcination, calcium-oxide utilization, and additive efficiency were determined.
Electron beam flue gas technology for SOx and NOx simultaneous removal: its process and chemistry evolution from power plants to diesel off-gas treatment
