Design And Experimental Study On Mixing Device For Granular Materials

The use of crop stalks has existed in human civilization for a long time,but crop straw has not been fully utilized in a relatively long historical period.In particular,the serious environmental pollution problems in recent years are caused by the burning of straw in rural areas.China has very rich crop straw resources,and how to effectively use it is a major challenge for China's three issues of agriculture,the countryside and farmers.Although the use of straw to feed ruminants such as cattle and sheep can reduce the production cost,due to the characteristics of straw in the cell wall of the straw,it has the characteristics of low nutritional value and low utilization rate.The straw raw material is processed through solid state fermentation technology.The treatment makes the product after fermentation has the characteristics of high crude protein content,high animal feeding rate,wide application range,etc.So this technology has a great application prospect.However,the current production of straw fermentation feeds is mainly based on traditional techniques and devices.It has the characteristics of large labor intensity,low production efficiency,and occupation of land resources.Therefore,it is necessary to develop a new type of fermentation device.The key technical difficulty of the fermentation device lies in the control of the fermentation environment,with the emphasis on heat and mass transfer,and the homogeneous mixing of the materials is the difficulty in heat and mass transfer.Based on previous researches,this topic uses the characteristics of the draft tube in the liquid fermentation process,combined with the vertical screw conveying structure in the process of solid material mixture,a new type of straw feed mixing device was designed.After installation,debugging and pre-testing,corn popcorn was used as raw material and the standard deviation of sample weight distribution was used as the mixing index to study the effects of screw pitch,loading coefficient,speed of the screw and the height of dead zone separators on the bottom margin of the draft tube on the mixing process.The main jobs and conclusions of the test are as follows.(1)A straw feed mixing device was designed and manufactured,which adopts a position-adjustable draft tube structure,and tests for different available materials to enter the gap.(2)The standard deviation of the sample weight distribution fluctuates during a period of time before homogeneous mixing,but the duration of the fluctuation is also different under the different control conditions,so the overall mixing effect is also different.(3)Regardless of the loading coefficient,the influence on the standard deviation of sample weight distribution of the height of 170 mm from dead zone separator to the bottom of the draft tube is better than the height of 70 mm,and the height of 70 mm is better than the height of 270 mm.When the height of the draft tube's bottom edge to the dead zone separator is controlled by 170 mm,and the loading coefficient is 0.2,the influence on the standard deviation of the weight distribution of the sample is better than the loading coefficient of 0.4,and the loading coefficient of 0.4 is better than the oading coefficient of 0.6.When the loading coefficient is 0.4 and the height of the bottom edge of the draft tube from the dead zone separator is 170 mm,the influence of screw pitch 200 mm on the standard deviation of the weight distribution of the sample is better than the screw pitch 150 mm.When the loading coefficient is 0.2 and the height of the bottom edge of the draft tube from the dead zone is 170 mm,the screw pitch is 200 mm and the screw rotation speed is 40 r/min,the mixing effect is better than the screw rotation speed of 10 r/min,and the mixing effect of screw rotation speed 10 r/min is better than the screw rotation speed 20 r/min,and the mixing effect of screw rotation speed 20 r/min is better than the screw rotation speed 30 r/min.(4)When the loading coefficient is 0.6,the amount of material that can be processed is large,the operatational loading coefficient of the current device is the maximum.When the bottom edge of the draft tube is separated from the dead zone separator by 170 mm,the test result is the best.