Experimental Study on Charge Characteristics and Elimination of Food Powder by Spiral Transportation
In order to provide theoretical basis and technology for removing static electricity from food powder packaging,the charge characteristics and static electricity elimination methods of food powder in spiral trans-portation were studied.Firstly,Faraday tube was used to build an electrostatic test platform for spiral conveying of food powder.Wheat starch and wheat flour were used as test materials to test the influence of spiral speed and conveying length on powder charge.Then,based on the theory of contact electrification and electrostatic balance,the method of changing the surface induced potential of the conveying device,reducing the total potential differ-ence between the conveying device and the powder,and reducing the electric charge during the spiral conveying of the powder was proposed,and the experimental verification was completed.The average charge-mass ratio of wheat starch with an average particle size of 20 and wheat flour with an average particle size of 100 were 0.22 nC/g and 0.42 nC/g respectively at static state,and 0.4 nC/g and 0.47 nC/g respectively at static saturation state.Before the powder reaches electrostatic saturation,the average charge-mass ratio of the powder decreases with the increase of the screw speed and increases with the increase of the conveying length when the screw speed is 80～120 r/min.When the pressure difference of the screw feeder reaches 100 V,the charge-mass ratio of wheat starch and wheat flour decreases by 22%and 23%respectively.The results show that the friction contact be-tween the powder and the screw feeder is the main reason for the increase of the charged energy of the food pow-der.The particle size,screw speed and conveying length have significant effects on the charged energy of the food powder.By changing the surface induced potential of the screw conveying device to reduce the charge of powder,it provides a reference for the technology of electrostatic removal of food powder.
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