Ventilator fan design: Present state and some prospects

Abstract

1. Nominal (rated) static efficiencies of mine ventilators and the weighted-mean values in the normal region of operation do not characterize their operational cost effectiveness, which is determined by the weighted mean efficiency calculated over the whole region of their possible operation. 2. Production-line axial and centrifugal ventilators have approximately equal weighted mean static efficiencies, the values of which (0.54–0.58) are much lower than the rated efficiencies of production-line machines (0.8–0.86) and are close to the mean value of the operational efficiencies of acting ventilators (0.5–0.54). 3. The required ventilation regimes of mines continually change; therefore to ensure cost effectiveness of operation of ventilators and to increase the efficiency of ventilation systems it is necessary to increase the adaptive properties of ventilation plants; this can be most effectively accomplished by sectionalizing the axial ventilators and replacing the equipment in the ventilation plants. 4. Sectionalized axial ventilators with not more than three sections (stages) can give the required range of pressures, have higher weighted mean static efficiencies (0.656), and permit the creation of ductless ventilator plants with high adaptive properties. 5. Ventilation plants with centrifugal ventilators and controlled drives are more expensive, less reliable, and less cost effective; therefore they should not be used in mines with deep changes in the required pressure and throughput. 6. The present method of duplicating the whole system in main ventilation plants and having no standby switching air door systems reduces the reliability of ventilation plants below the level for safe conduct of underground operations. 7. The most promising system for mine ventilation comprises ductless ventilation plants with vertical sectionalized axial fans with synchronous drives.