| In order to meet the needs of ultra clean emission and deep energy saving,China’s industrial layer fired boilers are promoting the transformation of pollutant emission reduction and waste heat recovery.However,there is a lack of evaluation research on the technical route suitable for China’s national conditions and economic rationality,so it is necessary to give a scientific and systematic evaluation method for the coordination of boiler energy efficiency and pollutant emission.This paper investigates and analyzes the existing boiler air pollutant treatment technology route,studies the key problems of low nitrogen combustion and efficiency,matching of air pollutant control and tail gas treatment,and waste heat recovery of low-temperature flue gas through field experiment and engineering design calculation,and establishes a comprehensive evaluation method of layer combustion furnace system considering economy and energy consumption.According to the evaluation method of the system,the key mathematical models of denitration system,dust removal system,desulfurization system and waste heat recovery system are established.According to different working conditions,the key mathematical parameters of four systems are determined,such as the liquid gas ratio of desulfurization system.The calculation methods of resource and energy consumption of four systems under three emission standards are explored.Based on the calculation results of resource and resource consumption,the economy and energy consumption of desulfurization system can be evaluated.The denitration system uses low nitrogen combustion,SNCR,SCR technology and their coupling technology,the dust removal system uses bag dust removal,electric bag composite dust removal and wet electric dust removal technology,the desulfurization system focuses on limestone method,quicklime method and magnesium oxide method,and the residual heat recovery system uses direct contact heat exchange technology.In terms of NO_x emission reduction,through field experiments,the relationship between low nitrogen combustion transformation and boiler combustion efficiency is obtained: the research results show that low nitrogen combustion transformation can improve boiler efficiency by 1% ~ 1.5% on average.The boiler efficiency is converted into economic and energy consumption indicators,and based on the energy efficiency evaluation system of denitration system,the research results show that the economic necessity of low nitrogen transformation of layer combustion furnace is strong.For example,under the emission standard,the annual average cost of low nitrogen combustion technology is 2.5 million yuan less than SNCR technology.The energy efficiency of the dust removal system is evaluated.The results show that the bag dust removal system has the best economy.Compared with the electric bag and wet electric dust removal,the annual dust removal cost can be saved by 550000 yuan,and the energy consumption is the lowest when the boiler load is less than 84%.For a single 116 MW layer fired boiler,the results show that: on the basis of the desulfurizer price set in this paper,according to the three emission standards,the quicklime method has the best desulfurization economy;The power consumption of Mg O desulfurization method is the least,saving at least 20 TCE;Under different emission standards,the curves of three desulfurization costs with sulfur content have intersection points.Aiming at the waste heat recovery of flue gas,the design and calculation process of waste heat recovery system of Stoker furnace is established,and the economy and energy consumption of the system are evaluated based on this.The economy and energy consumption of the system are positively correlated with the flue gas inlet temperature and boiler load,and negatively correlated with the flue gas outlet temperature.For a single 116 MW grate fired boiler,the net income of the waste heat recovery system can reach 1-2.5 million yuan / year. |
