Study On Mechanical Properties And Design For Waste Heat Recovery Device Of Cement Rotary Kiln

Rotary kiln is the core equipment of dry and wet production lines for cement clinker.It is the source of life and power for cement plant.Ensuring its safe and efficient production is the key to improve the economic efficiency of cement plant.Rotary kiln is made up of cylinder,firebrick,gear ring,block wheel,wheel and roller.The gear ring is the main transmission device,roller-wheel combinations are the main bearing device,the block wheel is a device to prevent the cylinder from moving.In the process of cement clinker production,when the kiln temperature rose to a certain extent,excessive deformation will occur between the cylinder and firebrick due to thermal stress and impact loading,resulting in the mutual extrusion between the adjacent firebricks inside of the cylinder.When the extrusion stress is greater than the strength of firebrick,the surface of refractory brick will be deformed and damaged.Considering the huge maintenance costs and the great economic losses caused by downtime,it is necessary to carry out in-depth research on the complex mechanical behavior of large-scale cement rotary kiln with thermal-structural coupling.In this paper,?2.75 × 50.95 m cement rotary kiln is used as the research object,the following work have been done:(1)The present research situation and shortcomings on the mechanical properties and heat recovery of rotary kiln cylinder are analyzed and summarized.The effect of temperature on the mechanical properties of rotary kiln is pointed out and it is suggested that a large amount of radiation can be recycled.(2)The finite element model of the rotary kiln cylinder and its supporting structure are established by ANSYS software.Cylinder and other structures are used in the way of sub-grid division,and the finite element model unit is made more regular by means of the MESH200 unit.The static model of the rotary kiln was analyzed without considering the temperature.The contact analysis between the roller-wheel combination is established,and the contact stress between the roller and wheel is calculated.(3)The thermal-structural coupling analysis of the cylinder and its supporting structure are carried out.And the maximum equivalent stress is 252 MPa,which occurs in the cylinder area between the first gear support and the second gear support.And it is compared with the maximum equivalent stress 32.6MPa obtained by static analysis,which increases 219.4MPa.It indicates that thermal stress is the main reason for the deformation of the cylinder,which cannot be neglected in the analysis of the rotary kiln stress.(4)An experiment model of vacuum heat collector for rotary kiln cylinder is designed.The circulating cold water system is used for the device to absorb heat from the surface of kiln,and the radiation heat transfer in the vacuum has the highest efficiency.Kiln surface is cooled while the water temperature is raised for human bathing.The design idea,technical innovation point and design principle of the device are introduced,and the stability of the model is verified.The recovery efficiency of the waste heat recovery is 62.9%,which shows that the recovery efficiency is considerable.