Numerical Simulation Of Combustion Performance And Structural Optimization Of LNG Submerged Combustion Gasifier

Gas fuel is widely used in power generation,metallurgy,building materials and other industries with its clean and high efficiency characteristics.As the most important component of gas combustion,the performance research of burner is highly concerned by scholars at home and abroad.At present,how to further improve combustion efficiency and achieve green combustion on the basis of meeting the basic burning demand become the top priority of burner performance research.The physical condition of the fuel has a great influence on the combustion effect.The structure of the burner also can improve the combustion conditions to a certain extent.In this paper,based on LNG submerged combustion vaporizer(SCV)as the research object,its chemical reaction mechanism of combustion was analysed and structure improvement scheme was put forward based on the traditional burner structure,combustion performance of gas fuel in the burner combustion chamber was analyzed which has different structures,by means of numerical simulation,so as to provide the basis for optimizing the structure of burner research.In this paper,the combustion cold state field and the thermal field respectively were simulated.The burner's temperature,velocity distribution and the concentration distribution of the main components are compared and analyzed.It is found that the flow field of the burner is basically the same as that of the thermal field.In the thermal field,due to the disturbance effect of gas combustion heat on gas and air velocity,the flow velocity in some areas of the thermal field is higher than that in the cold field.In order to further explore the influence of the swirl structure on combustion process,the distribution of internal flow field and temperature field of burner whose swirl vane angle is45?,60?,75?was analyzed.The result shows that,when the gas passes through a small angle of the swirl blade,it will generate large swirl strength inside the burner.This produces a certain size of the reflux region which is conducive to the stability of flame combustion.The length of flame in the burner increases with the angle of the swirl blade.When swirl angle is 45?,the area of the combustion chamber is the largest and the flame temperature is the most uniform.Based on the 45?swirl angle,the design of the slit is added around the nozzle of the gas center of the cyclone.the performance of the cyclone with no slit,4 slits and 8 slits,and the temperature distribution of the swirl combustion chamber with these three structures were analyzed,by changing the velocity of the air at the entrance.Combined with the result of swirl combustion of a variety of structures,it can be analyzed that the NO_x content of main combustion products at the outlet of the combustion chamber.By computation,NO_x generation increases when the rotation Angle is larger,this is because that the combustion of gas combustion is not sufficient when the swirl angle is larger and will produce more pollutants.The result shows that,the 45?angle swirling burner with 4 slits has the most optimal combustion performance for reducing the flow resistance and the turbulence intensity of the outlet flow of the cyclone effectively,which helps strengthen burning.And increasing the mixed speed.But the temperature of the slotted swirl burner near the wall is lower,which relieves the high temperature corrosion on the wall surface.