LCA Of Desulfurization, Denitration And Dedusting Technologies In Coal-fired Power Plants

SO2, NOx, particulate matter is the main pollutant emissions from coal-fired power plants. In order to control SO2, NOx, PM, limestone-gypsum WFGD, SCR denitration technology, electrostatic precipitation technology and bag dust removal technology have been widely applied. In the process of construction and operation, the above equipment will bring potential issues of energy consumption, material consumption and environment impact. Based on a new look at the problem, in this paper, limestone-gypsum WFGD, SCR denitration technology, electrostatic precipitation technology and bag dust removatl technology were analyzed using the technique of life cycle assessment.1year of power plant’s operation as a functional unit, energy consumption, material consumption and pollutant emissions of the above four kinds of control technology were evaluated.The above four kinds of control technology were quantified over two life cycle phases: construction phase and operation phase in this paper. And energy, resource consumption and pollutant emission inventory lists of each stage were calculated. For the construction phase, the material and weight of each system main equipment were analyzed. By using Gabi software, the lists of energy, resource consumption and pollutant emission were gotten. For the operational phase, the algorithm were the same. Finally, conversion to energy consumption, material consumption and pollutant emissions of the system to run for1years, and the effect of energy consumption, resource consumption and pollutant to the environment in greenhouse effect, acidification, eutrophication, photochemical ozone creation and smoke and dust were analyzed.In this paper, special analyses of the SCR denitrification system under the condition of the same NOx concentration and different denitrification efficiency and different situations of the catalyst service life were compared. Special analyses of the limestone gypsum wet desulphurization system under the condition of different boiler load and different situations of sulfur content of coal were analyzed. Special analyses of bag dust removal system in different service life of the filter bag and filter cage were analyzed.Finally, the atmospheric pollutants emission reduction efforts of the above three technologies were compared.We found that energy consumption, resource consumption and pollutant emissions of SCR denitration technology in operation phase is far greater than that in construction stage. And SCR technology has achieved remarkable results in environmental eutrophication and acidification improvement. For SCR denitration technology, in the case that the entrance NOx concentration of SCR system are the same, environmental impact load reducing with the increasing of the denitration efficiency. The denitration efficiency decreases from92.5%to75%, and the environmental impact load of running stage increases by161.48%.With the increase of the catalyst service life, the impact on the environment of its production reduces. The catalyst service life increases from2years to5years, environmental impact load is reduced by60%.We found that energy consumption, resource consumption and pollutant emissions of limestone-gypsum WFGD in operation phase is far greater than that in construction stage. And Limestone-gypsum WFGD has achieved remarkable results in acidification improvement. For limestone-gypsum WFGD, under full load, the environmental impact is minimum.The environmental impact load of operation stage increases with sulfur content of coal increasing. The sulfur content increases from0.5%to3%, the environmental impact load increases by about46.42%.For bag dust removal technology, with the filter bag and filter cage annual consumption increasing, the life cycle environmental impact load increases.We also found that energy consumption, resource consumption and pollutant emissions of electric precipitator and bag dust removal technology in operation phase is far greater than that in construction stage. And electric precipitator and bag dust removal technology has achieved remarkable results in the improvement of smoke and dust. If the environmental impact load of particles without removal are not considered, the impact on the environment of different filter bag and filter cage service life is still quite large. In the yearly consumption of the filter bag and filter cage respectively2352and1176, it reaches39.08%.Based on the present level of technology, with the same treatment cost of SCR denitration technology, limestone-gypsum WFGD and electrostatic precipitation technology, the electrostatic precipitation technology is the most environment friendly, and limestone-gypsum WFGD is more environment friendly than SCR denitration technology in general.