Research On Detection Method And System Of The Powder Filling Rate In The Spiral Feeding Pipe

Spiral discontinuous quantitative feeding is a closed and safe industrial production method,which is widespreadly applied in the processing and packaging of powder materials.The powder filling rate is a key parameter for quantitative feeding,which has a great influence on the accuracy of quantitative feeding and production efficiency.The powder flow in the spiral feeding pipe is a gas-solid two-phase flow,and its movement is very complicated,which makes it difficult to detect the powder filling rate.Accurate detection of the filling rate of powder materials in the spiral feeding pipe has a large effect on industrial and agricultural technological designs,production process measurement cost control,product quality control,etc.In this paper,the powder filling rate measurement means and economy research on the powder filling rate in the spiral feeding pipeline were carried out.The detailed research includes:First,the research status of powder filling rate detection and capacitance measurement at home and abroad was analyzed,and capacitance method was used to measure powder filling rate.Analyzed capacitance detection method for powder filling rate and soft field effect of capacitance sensor,compared with the common capacitance sensor structure used for pipeline parameter measurement,combined with the uniformity requirement of capacitance sensor sensitivity field,designed spiral surface plate capacitance sensor to detect powder fill rate.The principle of measuring the filling rate of powder by the capacitance method was analyzed,and the theoretical formula of filling rate and capacitance value was obtained.The main influencing factors of the detection field are: the axial length of the polar plate,the opening angle of the source plate,the opening angle of the protective plate,and the semidiameter of the screening can etc.Secondly,based on the COMSOL simulation software,a three-dimensional simulation model of the powder filling rate capacitive sensor was established,the performance index of the sensor detection field was established.The influence of the structural parameters such as the axial length of the polar plate,the opening angle of the source plate,the opening angle of the protective plate,the semidiameter of the screening can on the field index of the sensor was analyzed,and the better value range of each parameter was determined.With the help of orthogonal simulation test design,found the optimal sensor structure parameters and obtained a capacitive sensor with a uniform sensitivity field.For the optimized capacitive sensor,the improvement effect of the soft field effect of the sensor was simulated and analyzed,and the nonlinear error of the sensor was obtained,which provides the design of measurement economy of the powder filling rate with the principle foundation.Then,for the weak capacitance output of the capacitance sensor and the requirement of high resolution for weak capacitance detection,designed the powder filling rate detection system of the spiral feeding pipeline.The economy includes the capacitance sensor、feeble capacitance measurement module、AD conversion module、main controller、display module and power module,adopted modular method to design the main program and each part of the program,and carried out economy debugging.Finally,using flour as the filling material,designed the test plan and content of the powder filling rate test,carried out the sensitivity field uniformity test of capacitance sensor,the calibration test of powder filling rate of capacitance sensor,the stability test of powder filling rate of capacitance sensor,and the test performance test of powder filling rate.The test shows that the uniformity error parameter of the sensitivity field is 5.51%;the nonlinear error of the capacitive sensor is ± 1.544%;the absolute error range of the sensor stability test is ± 0.0082 pF,and the relative error range is ± 0.81%;the absolute error range of the measurement economy of powder filling rate is ± 2.00%,and the relative error range is ± 3.30%.The research results help to improve the performance of spiral discontinuous quantitative feeding,and promote the widespread application of spiral discontinuous quantitative feeding.