STUDY OF THE PROCESS OF CALIBRATION OF CONFECTIONERY SUNFLOWER SEEDS

Abstract

The aim of the research was to make the mechanical and technological process of calibrating confectionery sunflower seeds with a vibrating sieve more effective by giving reasons for its rational methodical and technological parameters. The study of calibration of confectionery sunflower seeds had two stages: numerical simulation and experimental verification. For the first stage, the physical models for numerical simulation (in the STAR-CCM+ software package) of the movement of seeds with a vibrating sieve were: k-ɛ model of separated flow turbulence, gravity field, Van der Waals real gas model, discrete elements model, multiphase interaction model. The second stage, experimental verification of the models obtained, was carried out on a calibration machine (sizer) OKMF. Sieves of three types were selected: perforated sieves, rod sieves, and precision sieves (produced by laser cutting). The numerical simulation of moving the confectionery sunflower seeds with a vibrating sieve has allowed determining how changes in total concentration and productivity depend on the way of the input of the seeds, the sieve angle, the vibration frequency and vibration amplitude of the sieve. To make the seed separation process effective, the vibrating sieve is to operate with the maximum productivity equal to the seed input (1,202 kg/h), with the maximum total seed concentration (10.83%). Experimental studies of moving the seeds of confectionery sunflower with vibrating sieves of different types (perforated screens, rod sieves, and precision sieves) have allowed establishing how changes in total concentration, productivity, and consumed power of the calibrating machine depend on the seed input, sieve angle, and frequency of vibrations of the sieve. To make the seed separation process effective, the vibrating sieve is to operate with the maximum productivity equal to the seed input (perforated screens – 1.116 kg/h, rod sieves – 1,518 kg/h, precision sieves – 1,781 kg/h), with the following total seed concentrations: perforated sieves – 14.54%, rod sieves – 12.45%, precision sieves – 10.41%, and power P (perforated sieves – 0.24 kW, rod sieves – 0.30 kW, precision sieves – 0.35 kW) consumed by the calibrating machine must be minimum. Precision sieves (produced by laser cutting) have the best characteristics of their performance (q=1781 kg/h) and quality (θ=10.41%). For this, the frequency of their vibrations should be 5.9 Hz, and their angle should be 5°.