Analysis And Prediction Of Erosion Wear Of Vertical Centrifuge Transflux Rotating Parts

Vertical centrifuge has been widely used for clean coal dewateringin coal preparation industry due to its advantages: high separation factor,low product moisture, reliable performance, etc. In this paper, the erosioncharacteristics of coal particles acting on the transflux rotating parts,erosion wear characteristics and grey prediction of the common materialsfor transflux rotating parts were systematically studied when the verticalcentrifuge worked.The erosion characteristics of coal particles acting on the transfluxrotating parts in the centrifugal field were analyzed by using thetheoretical mechanics method. Results show that:(1) the erosion velocityof coal particles acting on scraper inside surface of the small end is11.77-16.39m/s, erosion angle is12.41°-45.29°; the erosion velocityacting on the scraper blade surface increases gradually from the small endto big end, the maximum value is0.61m/s.(2) the erosion velocity of coalparticles acting on protection ring outside the bell jar is19.05m/s,erosion angle is58.09°; the maximum erosion velocity acting on uppersurface and profile of the bell ribs is0.67m/s and22.42m/s, respectively.The distribution characteristics of coal particle velocity field in thecentrifuge flow passage were analyzed by using FLUENT software.Results show that:(1) the maximum velocity of coal particles acting onscraper inside surface of the small end is12.5m/s, and it reaches thevalue at the bottom of the inside surface; the velocity acting on thescraper blade surface increases gradually from the small end to big end,the maximum value is32.2m/s.(2) the velocity of coal particles actingon the lateral surface of the bell jar increases gradually from inside tooutside surface, and the maximum value is21.5m/s; the velocity of coalparticles acting on the inside surface of the protection ring outside the belljar is32.2m/s.(3) the maximum speed of coal particles moving onscraper and bell jar occurr on the most serious erosion areas, the resultsconsist with actual situation.The erosion wear properties of Q235A, Cr12Mov, ZG310-570andQ345A were studied by using the sand blasting experiments. Results show that:(1) the erosion-wear resistance gradually reduces in the orderof the Q345A, ZG310-570, Cr12Mov and Q235A.(2) the weight loss rateincreases firstly and then decreases with the increase of erosion angle,and it reaches a maximum at the erosion angle of30°.(3) the main wearmechanism of material is micro cutting at the low erosion angle, and it isfatigue fracture caused by repeated plastic deformation at the high erosionangle.The grey prediction of the loss of weight and thick induced byerosion wear for Q345A was made and the prediction precision ofdifferent dimensions and modes were analyzed. Results show that:(1) theprediction accuracy of the loss of weight for GM (1,1) mode decreasesfirstly and then stabilizes with the increasing dimension from5to10.(2)the prediction accuracy of the modes reduces in order of residual equaldimension and new information model, equal dimension and newinformation model, residual correction model, old information model.(3)the prediction results of the loss of thick residual correction GM (1,1)model for Q235A materials consist with the measured data, thus it has agood prospect.