Application Research Of Selective Non-Catalytic Reduction De-NO_x Technology (SNCR) In CFB Boiler Units Of Power Plant

As the restrictions of environmental pollution and its enforcement become more and more strict, thermal power plant air pollutants’ emission standard cannot meet the requirements of regional atmospheric governance. It will also affect the people’s living conditions and the enterprise long-term development. NOx emission is the formation of acid rain and one of the most important reasons of atmospheric ozone depletion. It can also generate photochemical smog pollution under certain conditions,and bring direct and potential hazards to human health, ecological system and building facilities. The coal-fired power plant air pollutants emission standards(GB13223-2011) has limited the discharge of NOx concentration under 100 mg/Nm3 in key areas of existing thermal power project. However, employing the traditional control measures, such as dust removal and desulfurization equipment, will not meet the criteria. Therefore, the existing thermal power plant must reform the technical transformation, implementation of denitration project according to the national and local regulations and policies.The research focuses on the analysis and designation of the Midong thermal power plant circulating fluidized bed boiler flue gas denitration project. Based on the detailed investigation, basic conditions of power plant coal-fired boiler NOx formation mechanism were studied in domestic and overseas. Furthermore, the main scheme of the selection of flue gas denitration process were compared, and finally we chose selective non-catalytic reduction(SNCR) technology to implement the project of flue gas denitration transformation. In circulating fluidized bed boiler, the determination of flue gas oxygen content and furnace temperature, SNCR reaction conditions was studied. By considering the reaction of the SNCR technology principle,characteristics and the selection of reducing agent, we find the best NOx removal effect at the lowest cost; From the security and economy’s point of view, the project uses urea as a reductant in spray, determine appropriate denitration efficiency,determine the location and number of injection points. After reforming the NOxemission system, the plant will meet new coal-fired power plant air pollutants’ emission standards.SNCR flue gas denitration system must consider urea particles dissolve, heating temperature, etc., so the system mainly include the reducdants’ resolve and storage process, transmission process, the dissolution of dilution water, mixed distribution,injection system, control system, etc. The key points of building a new SNCR denitration urea dissolve station include arrangement reductant and storage systems,the dilution water utilities, reducing agent and dilution water pump, electric and thermal control system.Through monitoring pollutants’ emission condition before and after the technical transformation, and the waste water, noise, solid waste discharge situation of research,we analyze of the environmental impact of the project, and reconstruct the flue gas denitration environmental quality to present situation appraisal.