Design And Experimental Study Of Mixed Flow Drying Tower For Cyperus Beans

Cyperus beans is a new type of oilseed economic crop that integrates grain,oil,animal husbandry and feeding.It is expected to become a high-quality resource to replace imported soybeans and solve the long-term problem of China’s grain and oil security.The drying of the Cyperus beans after harvest is one of the key links in whole process of mechanized production of the Cyperus beans.At present,the main method of sun-drying can not meet the requirements of large-scale production and quality of Cyperus beans,so it is urgent to develop a special drying equipment for Cyperus beans.In this paper,based on the traditional mixed flow grain drying tower,CAE technology was used to simulate and optimize the key components of the drying tower,which solved the problems of blocking and uneven heating in the circulating grain discharging system.In addition,the influence of hot air temperature on the drying quality of Cyperus beans was also studied.The main research contents are as follows:(1)Structural design of Cyperus beans mixed flow drying tower.In this paper,it was carried out that the calculation and selection of natural gas burners and blower fans,the parameter design of drying system,lifting equipment;Secondly,this paper used the discrete element method to simulate the movement process of Cyperus beans in the Grain discharge wheel and screw conveyor,and carried out bench test according to the simulation results.The best combination parameters of the Grain discharge wheel were obtained: the blade width is78 mm,the discharge gap is 118 mm,and the discharge port width is 335mm;And the best combination parameters of screw conveyor were obtained: screw conveyor diameter is250 mm,screw conveyor speed is 80r/min.The problems of blockage and uneven discharge in the circular discharge device are solved.(2)Optimization design of drying chamber based on EDEM-Fluent coupling.In this paper,ICEM was used to perform structured mesh division of the model of the drying chamber established by Solidworks.Using the EDEM-FLUENT coupling method to conduct two-way coupling simulation on the temperature field,wind speed field,motion and heating of Cyperus bean particles in the drying chamber of the drying tower,while the DDPM model is selected,and the SST K-omega turbulence equation,Hertz Mindlin(no slip)contact mechanics equation and Ranz&Marshall heat transfer equation are used.Then the spatial arrangement of angular boxes in the drying chamber of the drying tower was optimized.The simulation results showed that when the horizontal spacing of the angular boxes is less than 310 mm,there would be some problems,such as low space utilization rate of the drying chamber,areas that cannot be dried,and large particle temperature difference between the inlet and outlet ends;When the horizontal spacing of the angular boxes is more than 310 mm,there would be a short contact time between the Cyperus beans and hot air,the flow field is not uniform,and there was an area that cannot be dried.So,310 mm was selected as the horizontal spacing of the angular boxes in the drying tower of Cyperus beans.The problems of clogging and uneven heating in the drying chamber were solved.(3)Effect of hot air temperature on the drying quality of Cyperus beans.In this paper,a mixed flow drying tower was used to carry out the drying experiment.And the Cyperus beans were dried with hot air at 45 ℃,50 ℃,55 ℃,60 ℃,65 ℃,70 ℃ and 75 ℃ respectively,then the drying quality of Cyperus beans was evaluated by moisture content,drying time,hardness,rehydration ratio,fat content,protein content,ash content and other indicators.The results showed that when the hot air temperature was 65℃,the drying time was short(15.5h),the hardness was low(151.23N),the rehydration performance was good(1.31),the fat content was high(19.5%),and the protein content was high(10.7%),ash content was low(1.75%).Therefore,65°C was selected as the hot air temperature of the Cyperus beans mixed flow drying tower.(4)The test study of Cyperus beans mixed flow drying tower.In this paper,a performance test was carried out on a mixed-flow drying tower for Cyperus beans.According to the test of drying characteristics,the drying process in the drying tower was mainly a deceleration process,and the drying rate gradually decreased with the decrease of moisture content;Secondly,the drying unevenness was less than 2%,the increase of the breakage rate was less than 0.5%,and the color was normal,which met the national standards.Finally,the initial drying mass,initial water content,precipitation range and unit heat consumption were7.8t,46.3%,30.8% and 986.76kcal/kg,respectively,which met the design requirements.