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Published: Kem. Ind. 53 (9) (2004) 393–400
Paper reference number: KUI-24/2003
Paper type: Original scientific paper
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Increasing the Efficiency of Oilseed Processing through Application of the New Procedure Parts of Screw Presses with Improved Wearing Resistance

V. Marušić, D. Štrucelj and Ž. Ivandić


Oil screw presses represent a striking example of tribosystem in which, due to the the abrasive (SiO2) present in oilseeds, the wearing out cannot be avoided, but by application of appropriate tribological procedures the material losses can be reduced. Knives installed on walls of the yoke in the pre-pressing (type PP) and final pressing device (type HP) were investigated by comparing the wear resistance of the carburised surface layers (usually used in oil mills) and newly introduced protection procedures: boron and vanadium carbide protective layer application (so called duplex procedure), thermal coating of multilayer SiC + DLC and plasma spattering of Al2O3 and Al2O3+P (additional phosphatizing of Al2O3 layer). The comparison of protective layers along the operational fields of the press was carried out on the basis of wear intensity It, calculated from the mass loss of the knives against the mass of processed sunflower seeds. The amount of the hulls was determined in sunflower seed and in ground material prior to the entrance of the presses. In the kernel and in the hull of the seed, in ground material before pressing and along operational fields of both presses as well as in the cake at the exit of the presses, oil, water and SiO2 contents, were monitored. It was established that the increase of knife wearing resulted in increasing of residual oil quantities in the final cake (from 19.5 % to 24.1 % in PP and 8.6 % to 11.5 % in HP press). Simultaneously, fine-size particles in crude oil increased from the initial 1.5–2 % up to 10 %, for which amount of the installed capacity of pressing plant was reduced. After comparison of carburised knives and by duplex procedure vanadium protected ones, not only an estimation of cost reduction for each ton of processed sunflower seed was foreseen, but also the essential decrease of indirect losses (through the reduction of wearing-out of the parts of filter presses for crude oil as well as fuel and hexane consumption) was given. This procedure increased the yield of the installed capacity and reduced the number of standstills, caused by the replacement of worn-out knives, from four to two standstills a year.

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screw presses, operational components, protective layer, extraction efficiency, sunflower seed