Research On Synergistic Processing Technology Of Gas Boiler Flue Gas Waste Heat Recovery And Low No_x Emission

Energy saving and clean emissions are essential for social and urban development.The temperature of the flue gas discharged from the gas fired boiler is high,which contains a lot of waste heat and NO_x.If high-temperature flue gas is directly discharged,it will cause more serious energy waste and air pollution.In order to improve the overall thermal efficiency and reduce NO_x emissions,flue gas waste heat recovery and low NO_x emission technology have become one of the most important issues today.In order to improve the gas boiler flue gas waste heat recovery and NO_x emission reduction effects,this paper conducts research on the synergistic processing technology of gas boiler flue gas waste heat recovery and low NOx emission from the perspective of energy,environmental protection and economic analysis.The flue gas waste heat recovery and NO_x emissions performance under multi-factor variable operating conditions are experimental studied and simulated.The synergistic enhancement principle of flue gas waste heat recovery and low NO_x emissions is deeply revealed.The high-temperature flue gas generated by the gas boiler directly contacts and exchanges heat with the spray water in the flue gas heat exchange section of the spray tower.The waste heat recovered by the spray water partly used to preheat the return water of the heating network,and partly used to preheat and humidify the combustion air.The humidified combustion air can increase the dew point temperature of the flue gas,which is not only beneficial to the waste heat recovery of flue gas condensation,but also can achieve the effect of low NO_x emissions.This paper experimentally studied and analyzed the system's waste heat recovery and NO_x emission reduction effect under different working conditions.The analysis results show that the system's heat supply network waste heat utilization efficiency decreases with the increase of the heat supply network return water temperature and increases with the increase of spray water flow rate.The experimental results show that when the moisture content of the combustion air is increased to 49.0 g/kg_{dry air},the dew point temperature of the flue gas has increased by 6.4?.When the heat supply network return water temperature is 45?,and the spray water flow rate is 0.83 m³/h.The flue gas waste heat utilization efficiency of the heat supply network is increased by 6.9%.The average NO_x emission concentration can be reduced to 50.0 mg/m³,which is a reduction of 61.4%.Synergistic benefit analysis shows that when the spray water flow rate increases,the liquid-gas ratio of the combustion air humidification section of the spray tower gradually increases,and the moisture content of the combustion air also gradually increases,thus enhancing the latent heat recovery of flue gas.At the same time,the increase in the moisture content of combustion air also helps to reduce the NO_x emission concentration of flue gas.Based on the experimental research results,this paper conducted a simulation and optimization economic analysis and studied the applicability of the system in 10 t/h-100 t/h boilers.Under the 10 t/h boiler,the gas saving cost of the system is 3.4×10⁵ CNY,and the investment payback period is 0.50 years.Under the 100 t/h boiler,the gas saving cost of the system is 3.4×10⁶ yuan,and the investment payback period is 0.47 year.Finally,based on the energy flow analysis of the system,the system operation process is optimized,and the simulation calculation is carried out based on the optimization scheme.The flue gas waste heat recovery and heat network waste heat utilization effects of the optimized system were analyzed.Under the condition of 40?heat supply network return water,the maximum recovery efficiency of flue gas waste heat is 15.6%,the heat supply network waste heat utilization efficiency is 11.8%,the NO_x emission concentration is 64.3 mg/m³,which is a reduction of 50.3%.The experimental and analytical results show that the gas saving can be realized by using the waste heat of the heat supply network,and at the same time,there is a better effect of NO_x emission reduction.This technology enjoys advantages in energy saving,environmental protection and economic benefits,and has a better promotion value.