Optimising shaft pressure losses through computational fluid dynamic modelling

Abstract

In recent years, substantial progress has been made with respect to the definition and control of the primary energy requirements in underground mines. Little has, however been done to develop a more detailed understanding of how to limit the various pressure losses which are intrinsic to shaft systems. This is in spite of the fact that more than half of the pressures generated by the ventilation fans in deep level mines are dissipated as pressure losses within the shaft system.This paper presents research which has been completed to optimize the pressure losses which occur in shaft systems as a result of the ventilation air flowing through them. In this regard, the response of various shafts to the ventilation air flowing through them was measured. These results were evaluated against the current theory for the calculation of shaft pressure losses. Finally the results of the measurements and calculations were used to calibrate a Computational Fluid Dynamics model of the shaft systems. This model was then iterated to allow meaningful conclusions as to the specific make up of the shaft equipment which contributes the most to pressure losses in shaft.The results of the above analysis demonstrated that the current theory used for the evaluation of these pressure losses is deficient. The paper discusses these conclusions and the specific ramifications of the analysis.Finally, the understandings gained with regards to the above research are applied to the design and layout of equipment in mine shafts. In this regard, the shape and orientation of the shaft steelwork is evaluated and its specific interaction with the piping and fitting is evaluated. Coming out of this evaluation are specific recommendations for the design of future shaft systems. These recommendations are based on the above models and offer specific savings on the lifetime operating costs of shaft systems.