Study On Pollutant Emission Prediction Model Of Heavy-duty Gas Turbine Combustor

Heavy-duty gas turbine technology represents the development level of heavy industry in a country to a certain extent.With the increasing attention to the environmental pollution problems,pollutant emission from heavy-duty gas turbine has become a key issue in the research and development of heavy-duty gas turbine.Under the background of the urgent need to solve the air pollution problem,controlling the pollutant emission is one of the main methods to solve the pollution problem,and the research of pollutant emission prediction methods is the research foundation of pollutant emission control.In order to study the pollutant emission prediction problem in the combustor of heavy-duty gas turbine,the M701heavy-duty gas turbine was selected as the research object.The specific research content is as follows:Firstly,UG three-dimensional modeling software is used to build the physical model of the flame cylinder,and use ANSYS Mesh Module for meshing.On the basis,the computational fluid dynamics software,FLUENT,was used to carry out the numerical research on the gas turbine combustor.In order to consider a variety of conditions,the non-premixed combustion model and the MILD combustion model were selected as the combustion model during the numerical calculation.The main parameters that affect pollutant emission were taken as the research parameters,such as the inlet pressure,air mass flow rate,average temperature of combustion zone,inlet wind temperature,etc,and then the temperature,velocity and NOx distribution cloud images based on the two combustion models were analyzed.Then,the variation range of research parameters was expanded on the basis of numerical calculation results,and the response surface optimization method was used to numerically optimize the main air parameters,such as primary air temperature,secondary air temperature,cooling air temperature,gas temperature,primary air mass flow,secondary air mass flow and fuel gas mass flow.The data were analyzed in 36 cases based on non-premixed combustion and 152 cases based on MILD combustion.The results show that during the calculation based on the non-premixed combustion model,the NOx emission values within the study parameters are all less than 0.35g/kg,the import pressure increases from 1.15×10⁶Pa to1.38×10⁶Pa,and the NOx emission value decreases by 0.012g/kg.The air mass flow rate increased from 4.22kg/s to 5.16kg/s,and the NOx emission value decreased by 0.08g/kg.The average temperature in the combustion zone increased from 1668K to 1720K,and the NOx emission value increased by 0.03g/kg.During the calculation based on the MILD combustion model,when the average temperature in the combustion zone rises from 1460K to 1520K,the NOx emission increases from 0.16g/kg to 0.24g/kg,and the CO emission increases from 0.06g/kg to 0.24g/kg.When the import pressure increases from 1.29×10⁶Pa to 1.32×10⁶Pa,the NOx emission decreases from 0.24g/kg to 0.16g/kg,and the CO emission decreases from0.23g/kg to 0.06g/kg.When the inlet air temperature was 540K to 680K,the NOx emission value increased from 0.28g/kg to 0.33g/kg.When the inlet air temperature rises to 720K to880K,the NOx emission value decreases from 0.24g/kg to 0.18g/kg.The formula of pollutant emission prediction based on the non-premixed combustion model and the MILD combustion model can be obtained respectively.In addition,the response surface optimization method was used to analyze the sensitivity of the parameters in affecting the pollutant emissions.The results shows that primary air mass flow,primary air temperature,and secondary air temperature are the main sensitivity factors,which have a significant impact on NOx emissions,while the sensitivity of other factors is lower.The sensitivity of performance parameters is sorted by m_first>T_first>T_secondary>m_secondary>m_fuel>T_fuel>T_cooling.The primary air mass flow and the primary air temperature are inversely proportional to NOx emission.When the primary air mass flow increases from3.6kg/s to 4.5kg/s,the NOx emission decreases from 0.24g/kg to 0.16g/kg.When the primary air temperature rises from 720K to 880K,the emission value of NOx decreases from 0.24g/kg to 0.18g/kg.The secondary air temperature is in direct proportion to NOx emission.When the secondary air temperature rises from 720K to 880K,the NOx emission value increases from0.17g/kg to 0.22g/kg.The research results can provide a research basis for the NOx emission prediction of heavy-duty gas turbine combustor.