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Abstract: Energy and environment are drawing greater attention today, particularly with the rapid development of the economy and increase consumption of energy in China. At present, coal-fired power plants are mainly responsible for atmospheric air pollution. The selective catalytic reduction (SCR) technology is a highly effective method for NO X control. The present study identified and quantified the energy consumption and the environmental impacts of SCR system throughout the whole life cycle, including production and transportation of manufacturing materials, installation and operation of SCR technology. The analysis was conducted with the utilization of life cycle assessment (LCA) methodology which provided a quantitative basis for assessing potential improvements in the environmental performance of the system. The functional unit of the study was 5454t NO X emission from an existing Chinese pulverized coal power plant for 1year. The current study compared life cycle emissions from two types of de-NO X technologies, namely the SCR technology and the selective non-catalytic reduction (SNCR) technology, and the case that NO X was emitted into atmosphere directly. The results showed that the environmental impact loading resulting from SCR technology (66810 PET2000) was smaller than that of flue gas emitted into atmosphere directly (164121 PET2000) and SNCR technology (105225 PET2000). More importantly, the SCR technology is much more effective at the elimination of acidification and nutrient enrichment than SNCR technology and the case that NO X emitted into atmosphere directly. This SCR technology is more friendly to the environment, and can play an important role in NO X control for coal-fired power plants as well as industrial boilers. [ABSTRACT FROM AUTHOR]

Abstract: The rising popularity of incineration of municipal solid waste (MSW) calls for detailed mathematical modeling and accurate prediction of pollutant emissions. In this paper, mathematical modeling methods for both solid and gaseous phases were employed to simulate the operation of a 450t/d MSW-burning incinerator to obtain detailed information on the flow and combustion characteristics in the furnace and to predict the amount of pollutant emissions. The predicted data were compared to on-site measurements of gas temperature, gas composition and SNCR de-NO X system. The major operating conditions considered in this paper were grate speed and oxygen concentration. A suitable grate speed ensures complete waste combustion. The predictions are as follows: volatile release increases with increasing grate speed, and the maximal value is within the range of 700–800kg/m2 h; slow grate speeds result in incomplete combustion of fixed carbon; the gas temperature at slow grate speeds is higher due to adequate oxygenation for fixed carbon combustion, and the deviation reaches 200K; NO X emission decreases, but CO emission and O2 concentrations increase, and the deviation is 63%, 34% and 35%, respectively. Oxygen-enriched atmospheres promote the destruction of most pollutants due to the high oxygen partial pressure and temperature. The furnace temperature, NO production and CO emission increase as the oxygen concentration increases, and the deviation of furnace exit temperature, NO and CO concentration is 38.26%, 58.43% and 86.67%, respectively. Finally, oxygen concentration is limited to below 35% to prevent excessive CO and NO X emission without compromising plant performance. The current work greatly helps to understand the operating characteristics of large-scale MSW-burning plants. [ABSTRACT FROM AUTHOR]