Research On Heating Structure And Parameters Of Mineral Filler Heating Apparatus For Asphalt Mixture

Mineral filler is an important ingredient of asphalt mixture,and its temperature state has an important effect on mixture performance.The study of suitable heating structure and corresponding parameters of the mineral filler heating device for asphalt mixture mixing plant is of great practical value to improve the heating quality and efficiency of mineral filler,ultimately upgrading the performance of asphalt mixture.Based on the classification of current mineral filler heating technology,the paper puts forward a scheme of batch mixing type heating device with a vertical shaft by comparing and analyzing the principles and characteristics of different heating methods,analyzes its heating process based on the mechanism of heat transfer,obtains that the thermal conductivity of the mineral powder is low and the angle of repose is large,that is,the thermal conductivity is poor and the fluidity is not good,which will significantly increase the heating time.Therefore,the heating efficiency and heating quality are put forward higher requirements.A new heating device with discharge gate and flue gas guide plate is designed,and the measure of transforming such structures as flame tube and guide plate to zero thickness wall in ANSYS Space Claim is set in order to reduce needed computational resources.The mesh is generated in Fluent Meshing,and the boundary conditions of the flue inlet and outlet are determined by calculation.The heat exchange between the stirred particles and the flue gas(separated by the bottom and the cylindrical surface of the mixer)is reduced to the heat exchange between the flue gas and virtual outer zone with fixed temperature by setting the heat transfer coefficient to the bottom and cylindrical walls of the mixer respectively.Finally,the effects of designed structure and parameters—the number of flue gas guide plates,the position of flue gas entering into the side barrel,the shape of the flame tube and the aperture size of the tube—on the heating temperature and temperature uniformity of the wall surface of the mixer are analyzed by using virtual orthogonal tests in Fluent,and proper structure and parameters of the device are determined.The simulation shows that the better structural scheme is 8 guide plates,ring flame tube,gradient aperture size and flue gas entering into the side barrel from the side of the inlet,and thereby getting a higher heating temperature and better temperature uniformity on the wall of the mixer.For the ring flame tube,the better parameters are a ring diameter of 1150 mm of the ring tube and an aperture size of 20 mm.