Effects Of Exhaust Air Flow Control On Moisture Content Of Cut Tobacco In Thin Plate Dryer

The drying process is an important process for primary processing workshop of Cigarette Factory.The main purpose of the drying process is to control the moisture content of the dried cut tobacco in a certain range,and at the same time through the high temperature heating,so that the cut tobacco rapidly dries and expands,increasing the filling value and quality of cut tobacco.In this paper,SH626 thin plate drum drying machine was used as the research object.This paper discusses the influence of the optimization of the exhaust air flow control on the moisture content of the exported cut tobacco and improves the accuracy and stability of the moisture content of the exported cut tobacco.The main contents are as follows:(1)Based on the theory of heat transfer and mass transfer,the heat and mass exchange process of cut tobacco in the cut tobacco dryer was studied.The movement state of the cut tobacco in the cut tobacco dryer was discussed.The kinematics and dynamics knowledge were used to decompose the cut tobacco movement into circular motion and the projectile movement.Combining the cut tobacco movement with the heat and mass exchange process: in different stages of movement,cut tobacco and drum heat transfer methods are different.In the circular motion stage,the heat transfer mode is mainly heat conduction between the cut tobacco and the cylinder wall.During the projectile movement phase,convective heat transfer between cut tobacco and hot air is the main.(2)The theoretical analysis of the heat and mass exchange in the drum wascarried out.The moisture transfer was studied between the cut tobacco and the dry air in the drum.Based on the properties parameter of moist air,the migration of moisture and heat in the drying process was analyzed.The drying process of mass and heat was calculated.(3)The test of the exhaust air flow control of the drying process was carried out.Through the adjustment of the exhaust system valve and fan frequency,to control the exhaust air flow effectively,so as to adjust the moisture content of the cut tobacco changes.The results show that the control of the exhaust air flow has a good effect on regulating the moisture content of the exported cut tobacco,while reducing the energy consumption of the exhaust fan.(4)The results of this paper show that: within the scope of the test,the effective control of the exhaust air flow can improve the stability of the moisture content of the exported cut tobacco,and reduce the temperature fluctuations caused by frequent adjustment of the cylinder wall temperature.There is no effect on hot air temperature and hot air flow(or not obvious).