Recursive Subspace Identification Based Adaptive Predictive Control Design For Melt Pool Temperature During Laser Additive Manufacturing

Rotary kiln is the main thermal equipment in ceramic roasting.It is widely used in building materials,metallurgy,chemical industry,environmental protection and so on.It has the advantages of large production capacity,simple structure,good heat distribution,good agitation and high degree of mechanization.But the rotary kiln as a large thermal equipment,high energy consumption,work in a closed state,the impact of ceramic firing quality and production efficiency of the important parameters-the kiln temperature is difficult to accurately measure,resulting in rotary kiln Into the process of operating parameters difficult to master.As long as the boundary conditions are set accurately,the temperature distribution in the kiln,the distribution of the flue gas flow,the concentration distribution of the components and the combustion of the pulverized coal in the kiln can be obtained by numerical simulation.Production has become an important research tool.In this paper,the mathematical model of combustion,heat transfer and mass transfer process is analyzed,including continuous,momentum,energy and component equations,as well as additional turbulence model,radiation heat transfer model,combustion model,Mathematical model of combustion process:standard k-?turbulence model,eddy energy dissipation combustion model,P1 radiation model.Based on the operating parameters of the pulverized coal combustion process during the stable operation of the rotary kiln,the firing atmosphere of the rotary kiln was simulated.The results showed that the flame shape of the combustion flame showed a good hammer shape,and the temperature distribution in the kiln showed combustion zone,The rule of the area is basically the same as that of the actual condition,and the feasibility of the numerical simulation and the correctness of the boundary condition are proved.Secondly,the influence of different proportions of internal and external wind on the firing atmosphere of rotary kiln is studied.By changing the proportion of internal air,the temperature and velocity distribution under the corresponding conditions were obtained and compared and analyzed.The results show that the ratio of internal and external wind is 0.6 and 0.8,the temperature distribution is uniform and basically the same,the length of the burning zone is more than 8.6 m,which meets the requirement of ceramsite firing.The axial velocity is mainly affected by the external wind,and the radial velocity is determined by the velocity jet formed by the inner and outer winds.The larger the speed difference between the inner and outer winds is,the greater the radial velocity is,the proportion of the inner and outer winds increases,The resulting velocity jet is reduced and the radial velocity decreases.Finally,the paper studies the damage caused by the temperature of the kiln to the damage of the lining.When the lining of the rotary kiln is damaged,the temperature at the monitoring point of the kiln is in a linear relationship with the increase of the thickness of the kiln shed.Gradient rise,when the monitoring point temperature of 272.2 ?,the corresponding heavy refractory layer off 1/3 thickness.When the maximum temperature of the kiln table monitoring point is 298.41 ?,and the corresponding temperature range of the kiln table is R=750mm,it indicates that the fracture layer of the heavy refractory layer is off.When the monitoring site maximum temperature of 351.49 ?,and the kiln high temperature range R=1050mm,the rotary kiln heavy refractory layer has emerged the whole brick off,the monitoring point temperature of 351.49 ? can be set to alert temperature.