Structure Design And Experimental Analysis Of Combustion Channel For Hot Blast Stove

Hot blast stove is a kind of equipment which is used to heat and produce hot air by the heat and air generated by the combustion of fuel.It is the main auxiliary equipment for fluidized drying,spray drying,tower drying,tunnel drying and rotary drying.It is widely used in the field of grain drying.At present,the thermal efficiency of coal-fired hot air stoves commonly used in grain drying systems in China is only 60%~75%.A large part of the reason is due to incomplete combustion of pulverized coal.The problem of air distribution has become an important component and technical difficulty in improving the thermal efficiency of pulverized coal combustion.Reasonable ratio of air and coal is of great significance for improving combustion efficiency of hot blast stove and promoting energy saving and emission reduction.Firstly,the linear programming model of flue gas at the exit of combustion channel is established,and the optimization of air distribution parameters is carried out by genetic algorithm.Then,the structure design and parameter calculation of combustion channel are carried out according to the optimization results.Finally,numerical simulation and field test of pulverized coal combustion are carried out.In this paper,the following aspects of research are carried out around the design and test of the combustion passage structure of hot blast stove:(1)Optimize the air distribution parameters and design the combustion channel structure.A linear programming model with the mass flow rate of pulverized coal as the objective function and the heat and flow rate of flue gas as the constraints was established.The genetic algorithm was used to optimize the air distribution parameters.Based on the optimization results,the design parameters of the combustion channel are deduced.On this basis,a structure of the combustion channel of the suspended pulverized coal hot blast stove is designed,which provides technical support for numerical simulation analysis and field test research.(2)Carry out numerical simulation of combustion channel.The structure model of combustion channel was established by Gambit software,and the grid was divided and the boundary conditions related to numerical simulation were set up.The CFD simulation software Fluent was used to carry out numerical simulation,and the experimental results of temperature field and velocity field in the combustion channel were obtained.In order to study the influence of pulverized coal mass flow rate on combustion performance,seven working conditions were set up,0.14 Kg/s,0.28 Kg/s,0.42 Kg/s,0.56 Kg/s,0.7 Kg/s,0.84 Kg/s and 1 Kg/s.The numerical simulation results show that when the pulverized coal mass flow rate is above 0.42 Kg/s,the outlet flue gas temperature can meet the design requirements,and the peak temperature of the furnace appears in this range,while the average velocity of the outlet flue gas appears.The maximum degree appears at 0.7 Kg/s.This conclusion can provide a reference for the field test of pulverized coal combustion.(3)Field test of pulverized coal combustion was carried out.A hot blast stove model was set up and pulverized coal ignition and combustion tests were carried out.The flue gas flow velocity at the exit of the combustion channel is obtained by using the wind speed and pressure measuring instrument,and the temperature values at different measuring points in the combustion channel are obtained by using platinum rhodium thermocouple.The mass flow rate and heat quantity of the flue gas at the exit are calculated,and the results are compared with those of the numerical simulation and the designed value.The correctness of the optimization results of the genetic algorithm and the rationality of the numerical simulation results are verified.The results provide a basis for automatic control of pulverized coal combustion and improve the automation and efficiency of grain drying operation.The innovative points are:(1)the linear programming model of the flue gas outlet of the combustion passage of the hot blast stove is established,and a structure of the combustion passage of the suspended pulverized coal hot blast stove is designed by using the optimization results of genetic algorithm;(2)the combination of the hydrodynamic simulation test of the combustion passage of the pulverized coal hot blast stove and the field test ensures the performance index of the hot smoke outlet of the hot blast stove.To a large extent,it reduces energy consumption and shortens product development cycle.