Study On Dynamic Heat Transfer Of Cement Clinker Based On LBM

Grate cooler is one of the important equipment of cement clinker burning system.Its main function is to cool and transport cement clinker.It is the key to realize energy saving,emission reduction and green sustainable development of cement industry to study the heat transfer law of clinker in grate cooler,and then improve the cooling effect of clinker and the heat recovery rate of the system.In the process of heat transfer of clinker accumulation,due to the contact between particles,the temperature at the contact point which is named as high temperature red point area is higher.With the flow of the material layer,the high temperature red spot area separates from the contact area and contacts with the cooling air,thus increasing the overall heat transfer intensity.The effect of red spot zone is ignored in the static model of clinker stack heat transfer in the past.In this paper,the dynamic model of feature element is established on the basis of considering the red spot area of particles.Based on lattice Boltzmann method,the dynamic heat transfer law of clinker characteristic element and accumulation was studied.First of all,the size of bulk characteristic element of clinker accumulation is determined by permeability experiment.According to the average diameter and porosity of the particles in the cross section of the accumulation body,the static physical model of the characteristic element is obtained.Secondly,based on the self-designed particle angular velocity experiment platform,the spin velocity of particles at different pushing speeds is measured.Through lbm-sgs simulation,according to the distribution of flow field,the red point area under different air supply conditions is obtained.Through the slice experiment of clinker characteristic element,after the slice image processing and analysis,the number of red dot area is obtained.Based on the above experimental simulation data and the static physical model of the feature element,the dynamic physical model of the feature element is established by adding parameters such as particle spin speed,red point range and number of red point areas.Then,the coupled double distribution function lattice Boltzmann model of compressible flow is used to establish the characteristic element dynamic heat transfer mathematical model.After dealing with the basic parameters,boundary conditions and red dot area of the model,the mathematical analysis software is used for programming calculation.The cloud chart of the model temperature field is obtained by calculation,and the law of the average temperature of particles and the temperature of the outlet air is analyzed.The results show that the wind speed has a greater impact on the overall heat transfer effect than the pushing speed.Considering the heat exchange effect of particles and the recyclability of outlet air temperature,the reasonable air supply speed is 1.5-2 m/s,and the pushing speed is 20-25 times / min.Finally,the particle heat transfer experiment was carried out based on the self-designed cement clinker dynamic heat transfer experimental platform,and the temperature data of particles and outlet air were obtained.Compared with the results of the model,it is found that the average error of particle temperature is 8.6%,and the average error of air temperature is 10.5%.