Simulation Research On Flue Gas Condensation Waste Heat Recovery And Purification Of Gas-fired Boiler

With the development of the city,energy consumption and pollutant emissions have been greatly increased.Energy saving and emission reduction become the theme of urban energy development.As cleaning energy,natural gas is widely used for its highly calorific value.The combustion product of natural gas contains a large amount of water vapor and latent heat of condensation.If the temperature of exhaust flue gas is too high,it will inevitably cause a waste of energy.The high combustion temperature of natural gas increases the emission of NOX.How to efficiently recover the waste heat of flue gas and reducing NOX emissions have been imminent.First of all,this paper analyzes the advantages and disadvantages of the existing flue gas condensing waste heat recovery technology and NOx reduction technology,puts forward some suggestions for improving rate of waste heat from flue gas and reducing NOx emissions of gas-fired boiler,recommeds the flue gas waste heat recoery technology should be combined with NOx emission reduction technology.Secondly,the influence of flue gas temperature on the condensation rate of water vapor in flue gas and the heating efficiency of gas-fired boiler are analyzed by gas combustion characteristics and the influence of air humidity on the dew point temperature of flue gas and the effect of Q? on the heating performance of gas-fired boiler were studied.The results show that the higher the flue gas temperature is,the lower the condensation rate of water vapor in the flue gas and the lower the heating efficiency,the higher the air humidity is,the higher the dew point temperature is,the lower the Q? is,the lower the temperature of the supply and return water and the temperature of the exhaust flue gas.Finally,the conventional condensing flue gas waste heat recovery technology,the direct contact flue gas condensation heat recovery technology based on absorption heat pump and the direct and indirect flue gas condensation heat recovery technology based on air humidification have been simulated in full working condition about 2 tons of steam boiler.The differences in energy saving,economy and environmental protection of three kinds of flue gas condensation heat recovery technology are analyzed.The results show that the three kinds of waste heat recovery technology can respectively improve the heating efficiency by 3.46%,9.66% and 9.53%,save of 25 thousand and 900 yuan,68 thousand yuan and 67 thousand and 200 yuan.The investment recovery period are 2.32 years,3.23 years and 1.26 years,respectively.Due to save fuel and respectively reduce NOx emissions are 11.01 kg,28.89 kg,28.53 kg.The third kinds of flue gas waste heat recovery technology can reduce more NOx emissions for the furnace combustion temperature is reduced by air humidification.Therefore,it can reduce NOx emission more than 28.53 kg,but the actual value should be measured by the test.