Dynamic optimisation of deep-level mine refrigeration control

Abstract

Artificial cooling remains vital to the deep-level mining industry. This is mainly to ensure a safe underground working environment. Unfortunately, the refrigeration systems of South African gold mines are outdated. Aging infrastructure and increasing distances to active mining areas present this industry with a unique set of cooling challenges. Mines are deeper and more complex than ever, yet their refrigeration systems operate according to original design specifications. The importance of mine refrigeration systems adapting to a dynamic environment becomes evident. One solution to this challenge is to re-evaluate the control of refrigeration systems based on dynamic cooling needs. Control optimisation strategies were implemented on a case study to improve the overall performance of a refrigeration system. The implementation of these strategies resulted in multiple benefits for the mine. The operational performance of the refrigeration system was optimised, resulting in both service delivery improvements and energy efficiency. During summer months the chill dam temperature decreased by 1°C at a lower energy consumption of 38 MWh per day. This accumulates to a financial cost saving of R9 million per annum. This study proves that operational performance increases are possible through dynamic control optimisation of deep-level mine refrigeration systemsKunsmatige verkoeling bly onontbeerlik vir die ondergrondse mynboubedryf. Dit is hoofsaaklik om 'n veilige werksomgewing te verseker. Ongelukkig is die verkoelingstelsels van Suid-Afrikaanse goudmyne verouderd. Verouderde infrastruktuur en die toenemende afstande na aktiewe werksareas lei tot unieke verkoelings uitdagings. Myne is dieper en meer kompleks as ooit tevore, maar die verkoelingstelsels funksioneer steeds volgens oorspronklike ontwerpspesifikasies. Dit is duidelik dat huidige verkoelingstelsels nie opgewasse is vir die veranderende omstandighede nie. Een oplossing vir hierdie unieke uitdaging is om die beheer van verkoelingstelsels te herevalueer om aan veranderende verkoelings behoeftes te voorsien. Optimering strategieë is geïmplementeer op 'n gevallestudie om die algehele dienslewering van 'n verkoelingstelsel te verbeter. Implementering van hierdie strategieë het verskeie voordele tot gevolg gehad, onder andere verbeterings in dienslewering teen ʼn laer energie verbruik. Gedurende die somermaande het die temperatuur van die koue water dam gedaal met 1°C teen 'n verminderde energieverbruik van 38 MWh per dag. Dit lei tot 'n finansiële kostebesparing van R9 miljoen per jaar. Hierdie studie bewys dus dat operasionele verbeterings in dienslewering moontlik is deur dinamiese beheer van myn verkoelingstelsels