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Frigair 86: Summary of the mine cooling sessions 14–16 April 1986, Pretoria, South Africa
Conference reviews Frigair 86: summary of the mine cooling sessions 14-16 April 1986, Pretoria, South Africa
The papers on mine cooling reflected the great difficulties of cooling the working environments in very deep mines. As the depths of South African gold mines approach the 4000m level, the heat loads (particularly from the rock surfaces) constitute a major technical and economic challenge to mine designers. The papers can be grouped into four categories: environmental conditions, heat load prediction, refrigeration machines and refrigeration distribution systems. Firstly, the question of the thermal environmental requirements for underground working areas was dealt with in papers by A. J. Kielblock, 'Human heat stress in mining: a review', and P, C. Schutte et al. of the Chamber of Mines of South Africa Research Organization, 'Wetbulb temperature and metabolic rate limits for acclimatized men'. While the mines of the West German hardcoal industry are not as deep (maximum 1400 m) as the South African gold mines, higher geothermal gradients in Germany result in a similar general need for refrigeration. (The total installed refrigeration capacity in German coal mines is ~ 300 MW, while that in South African gold mines is ~ 1000 MW.) In a paper by G. H. Miicke (Bergbau Forschung, GmbH, FRG) 'Climate regulations and air-conditioning in deep German coal mines', recently introduced climatic regulations were summarized and examples were given of air-conditioning measures adopted to maintain acceptable temperatures. The second category, heat load prediction, was reviewed in a paper by S. J. Bluhm et al. of the Chamber of Mines of South Africa Research Organization, entitled 'Evaluation of heat flow from rock in deep mines the state of the art'. A complementary paper by P. Mousset Jones of the University of Nevada, USA and M.J. McPherson of the University of California, 'In situ measurement of the thermal transport properties in an underground airway', described tests carried out in North American mines. This paper also mentioned some aspects of the thermal problems in designing underground nuclear waste depositories, where much of the methodology is also applicable to mining. The third general category, concerning refrigeration machines, centred mainly on various designs of water chillers. A strong motivation behind these designs is the need to achieve the lowest possible temperature for water leaving an evaporator for mining applications, in order to minimize the quantity of cooling water to be circulated between the refrigeration installation on the surface and the underground workings. Various types of evaporators were covered. Two particularly interesting papers were presented on the prediction of centrifugal chiller performance. H. GroUius et al. (Atlas Copco Energas GmbH, FRG) presented a paper entitled 'Computer modelling of 0140-7007/86/060368 04503.00 ( , 1986 Butterworth & Co (Pubhshers) Lid and IIR
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performance of centrifugal water chillers m mine refrigeration installations'. This described a computer program for predicting the off-specification behaviour of single or two-stage chillers, as normally encountered during mine operation where both load and lift vary. The paper by R. Hemp et al. of the Rand Mines, SA., 'Routine measurements of the performance of underground refrigeration plants the use of a computer and an expert system', described the use of a chiller performance prediction program as a basis for comparison with plant measurements, in order to diagnose the reasons for any under-performance. The paper demonstrated the versatility of a personal computer in carrying out all the tasks from checking the input signals continuously lo producing diagnostic reports on performance. Finally, it was noteworthy that various new systems for distributing refrigeration in deep mines, some of which are already in the process of unplementatlon, were discussed. The paper by H. C. L. Baker Duly of Anglovaal Ltd, S.A., "The design and installation of a large capacity plant for low temperature mine a~r cooling', described a screw-compressor refrigeration plant located on the surface which employs a direct ammonia air finned-tube evaporator for cooling the downcast mine ventilation air. Particular emphasis was placed upon safety measures in the event of an ammonia leak. T. J. Sheer et al. from the Chamber of Mines of South Africa Research Organization presented a paper entitled 'Unconventional systems for removing heat from deep mines', which outlined the need for more cost-effective types of mine cooling systems lk~r deep mines. Three possible types of systems were described that are the subjects of current research investigations: lee systems: air cycle refrigeration systems, and closed-circuit distribution systems. The successful research carried out into the transportation of tee underground through pipelines was described. The paper by H. M. W. Eschenburg et al., "A thousand ton per day ice plant for underground cooling at Harmony Gold Mine', described the first large-scale realization of the use of ice. K. Andersen and F. V. Boldvig (Sabroe Company, Denmark) presented a paper entitled 'Vacuum ice a new method for production of large quantities of ice for cooling deep mines', which described one process that could meet the challenge of producing ice at lower costs for use as a mine coolant in the future. T. d. Sheer Envrronmenlal Engineering Laboratory, Chamber o/" Mines Research Organizalhm. South A trica
The papers on mine cooling reflected the great difficulties of cooling the working environments in very deep mines. As the depths of South African gold mines approach the 4000m level, the heat loads (particularly from the rock surfaces) constitute a major technical and economic challenge to mine designers. The papers can be grouped into four categories: environmental conditions, heat load prediction, refrigeration machines and refrigeration distribution systems. Firstly, the question of the thermal environmental requirements for underground working areas was dealt with in papers by A. J. Kielblock, 'Human heat stress in mining: a review', and P, C. Schutte et al. of the Chamber of Mines of South Africa Research Organization, 'Wetbulb temperature and metabolic rate limits for acclimatized men'. While the mines of the West German hardcoal industry are not as deep (maximum 1400 m) as the South African gold mines, higher geothermal gradients in Germany result in a similar general need for refrigeration. (The total installed refrigeration capacity in German coal mines is ~ 300 MW, while that in South African gold mines is ~ 1000 MW.) In a paper by G. H. Miicke (Bergbau Forschung, GmbH, FRG) 'Climate regulations and air-conditioning in deep German coal mines', recently introduced climatic regulations were summarized and examples were given of air-conditioning measures adopted to maintain acceptable temperatures. The second category, heat load prediction, was reviewed in a paper by S. J. Bluhm et al. of the Chamber of Mines of South Africa Research Organization, entitled 'Evaluation of heat flow from rock in deep mines the state of the art'. A complementary paper by P. Mousset Jones of the University of Nevada, USA and M.J. McPherson of the University of California, 'In situ measurement of the thermal transport properties in an underground airway', described tests carried out in North American mines. This paper also mentioned some aspects of the thermal problems in designing underground nuclear waste depositories, where much of the methodology is also applicable to mining. The third general category, concerning refrigeration machines, centred mainly on various designs of water chillers. A strong motivation behind these designs is the need to achieve the lowest possible temperature for water leaving an evaporator for mining applications, in order to minimize the quantity of cooling water to be circulated between the refrigeration installation on the surface and the underground workings. Various types of evaporators were covered. Two particularly interesting papers were presented on the prediction of centrifugal chiller performance. H. GroUius et al. (Atlas Copco Energas GmbH, FRG) presented a paper entitled 'Computer modelling of 0140-7007/86/060368 04503.00 ( , 1986 Butterworth & Co (Pubhshers) Lid and IIR
368
Int. J. Refrig. 1986 Vol 9 November
performance of centrifugal water chillers m mine refrigeration installations'. This described a computer program for predicting the off-specification behaviour of single or two-stage chillers, as normally encountered during mine operation where both load and lift vary. The paper by R. Hemp et al. of the Rand Mines, SA., 'Routine measurements of the performance of underground refrigeration plants the use of a computer and an expert system', described the use of a chiller performance prediction program as a basis for comparison with plant measurements, in order to diagnose the reasons for any under-performance. The paper demonstrated the versatility of a personal computer in carrying out all the tasks from checking the input signals continuously lo producing diagnostic reports on performance. Finally, it was noteworthy that various new systems for distributing refrigeration in deep mines, some of which are already in the process of unplementatlon, were discussed. The paper by H. C. L. Baker Duly of Anglovaal Ltd, S.A., "The design and installation of a large capacity plant for low temperature mine a~r cooling', described a screw-compressor refrigeration plant located on the surface which employs a direct ammonia air finned-tube evaporator for cooling the downcast mine ventilation air. Particular emphasis was placed upon safety measures in the event of an ammonia leak. T. J. Sheer et al. from the Chamber of Mines of South Africa Research Organization presented a paper entitled 'Unconventional systems for removing heat from deep mines', which outlined the need for more cost-effective types of mine cooling systems lk~r deep mines. Three possible types of systems were described that are the subjects of current research investigations: lee systems: air cycle refrigeration systems, and closed-circuit distribution systems. The successful research carried out into the transportation of tee underground through pipelines was described. The paper by H. M. W. Eschenburg et al., "A thousand ton per day ice plant for underground cooling at Harmony Gold Mine', described the first large-scale realization of the use of ice. K. Andersen and F. V. Boldvig (Sabroe Company, Denmark) presented a paper entitled 'Vacuum ice a new method for production of large quantities of ice for cooling deep mines', which described one process that could meet the challenge of producing ice at lower costs for use as a mine coolant in the future. T. d. Sheer Envrronmenlal Engineering Laboratory, Chamber o/" Mines Research Organizalhm. South A trica