The Study Of Numerical Simulation Of Combustion In The Corner-tube Gas-fired Boiler And Its Influencing Factors

As a kind of energy conversion device,boiler plays an extremely important role in economic development,especially in industry.Gas fired boilers with natural gas are used as fuel,clean and efficient,and have good water cycle and high thermal efficiency,so as to meet the requirements of energy conservation and emission reduction in our country.In this paper,a 130t/h angle tube gas boiler is taken as the research object.The numerical simulation method and the numerical simulation software Fluent are used to study the variable parameters of the combustion process of the furnace.Through the analysis of the combustion in the furnace,the velocity field,temperature field and the concentration distribution of NOx in the furnace are very comprehensive.To some extent,it has a theoretical guidance for the design and safe operation of the boiler.Through the numerical simulation of the combustion in a 130t/h angle tube type gas boiler under the design parameters,it is found that the combustion in the furnace is diffusion combustion,the flame is longer,the flame in the furnace is not adhered to the wall,and the filling degree is good.NOx is mainly located in the high temperature zone downstream of the flame zone and the interface between natural gas and air.The numerical simulations of the combustion of the furnace at the excess air coefficient of 1,1.1,1.2 and 1.3 are carried out.The results show that the flame length increases with the increase of the excess air coefficient,and the average temperature of the furnace increases first and then decreases with the increase of the excess air coefficient,when the excess air coefficient is 1.1,The average temperature of the furnace is the highest;when the excess air coefficient is 1.2,the NOx generated by combustion is the lowest.The numerical simulation analysis of the boiler furnace combustion heat load is carried out.The simulation results show that with the decrease of boiler heat load,the average temperature of the furnace decreases,the flow velocity of flue gas decreases and the concentration of NOx increases.So the full load should be kept in the actual operation process to reduce the generation of NOx.The preheated air can improve the average temperature of the furnace and reduce the temperature of the boiler exhaust.Therefore,the use of the waste heat of the flue gas to preheat the air has played a very good role in improving the energy utilization rate and energy saving and emission reduction.The results show that the average temperature of the furnace is the highest when the air preheating temperature is 450 K,the average temperature of the furnace is the highest.The average temperature of the furnace does not increase when the air preheating temperature is six,and the preheated air will produce NOx.It is certain that when the air preheating temperature is 450 K,the combustion result is the most ideal.