Emission Characteristics And Conversion Mechanism Of Nitrogen Oxide From Gas Turbines

The introduction of the West-East Gas Pipeline policy has made natural gas applications increasingly widespread.The problem of NO_x emissions generated during the operation of gas-fired gas turbines cannot be ignored.In order to study the law of NO_x emission from gas turbines and its transformation,this paper studied the effects of composition and operating parameters of yellow smoke from gas turbines on the emission of nitrogen oxides.Combined with the quantum chemical software Gaussian 09,the mechanism of NO_x generation after methane combustion in gas turbine operation.And the mechanism of NO-NO₂ conversion was studied.The main research contents and conclusions are as follows:（1）Simulating the thermodynamic and prompt NO_x generation mechanism during gas turbine operation,and calculating the relationship between reaction rate constant and temperature by using transition state theory.The results show that the thermal NO_x chain initiation step is the rate-limiting step of the entire thermal NO_x,and its activation energy is 86.47 kcal/mol,which is much larger than the non-limiting rate activation energy.The reaction rate constant changes very much with temperature.The activation energy of the CH+N₂ reaction in the chain initiation step of the prompt NO_x generation is relatively close to that of the C+N₂ reaction,and the reaction rate constant increases with increasing temperature.At 1500K,the reaction rate constant is close.Therefore,there is a competitive reaction when burning.（2）In view of the yellow smoke phenomenon of gas turbines,this paper measures the composition of flue gas yellow smoke,and analyzes the effects of operating conditions,production load and turbine outlet temperature on nitrogen oxide emission.The results show that the main component of yellow smoke is NO₂.In the start-up and single-cycle conditions,the NO₂ concentration of the flue gas is higher than the NO concentration,the concentration ratio is as high as 0.78,and the flue gas is yellow.Under the combined cycle and low load conditions,the production load increases,the NO and NO_x concentrations gradually increase,and the NO₂concentration gradually increases.Reduced,the yellow color of the smoke gradually becomes lighter until it is substantially colorless.The NO₂/NO_x concentration ratio decreases as the production load increases.When the turbine outlet temperature is lower than 565°C,the NO₂ content is higher.Therefore,reducing the low load running time and increasing the production load can help alleviate the yellow smoke phenomenon.（3）For the NO-NO₂ conversion mechanism,the reaction of the NO-NO₂conversion element was simulated,and the reaction rate constants at different temperatures were calculated.The effects of the composition and temperature of the flue gas on the conversion of NO-NO₂ were analyzed.The results show that there are two kinds of H radical and O2 reaction products,which are HO2 and OH and O radical.The main source of H radicals is produced by oxidation of CO.In the low temperature range,the CO oxidation reaction is slow,and the rate of H radicals generated is low.In the range of 800K-1000K,the main product of H and O₂ reaction is HO₂,and the oxidation of CO and the oxidation of NO are mutually coupled-promoted reactions;high temperature range,H and O₂ The main products of the reaction are OH and O radicals.The CO oxidation and NO oxidation coupling promote dissociation,while the NO₂ consumption ratio increases,and the NO₂content increases first and then decreases.