GB1582154A - Underground mine working including an air cooling plant - Google Patents

Description

(54) UNDERGROUND MINE WORKING INCLUDING AN AIR COOLING PLANT (71) We, PETER HERMANNS, a German citizen of Teichstege 10, 4230 Wesel, and HANS HENTING a German citizen of Teichstege 14, 4230 Wesel, Federal Republic of Germany, do hereby declare the invention, for which we pray that a Patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following Statement:: The invention relates to an underground mine working comprising an air cooling plant having a closed cooling medium circuit passing from above ground to below ground, which air cooling plant comprises a refrigeration plant connected in the circuit above ground and a heat exchanger connected in the circuit below ground, the cooling medium circuit being used for cooling a second cooling medium circuit installed below ground, which supplies at least one air cooler installed in the mine working, particularly at a face of the working.

This type of plant in a mine working makes possible the air-conditioning of the working, since it effects the removal of heat from the below ground working. Using an air cooling plant in a mine working avoids or at least reduces the disadvantageous effect on the climate underground of ambient temperatures which, without cooling, will increase with increasing depth of working. However, it is important that on one hand the air cooling plant in a mine working should be economical to run, and on the other hand when air cooling plant is installed in an existing mine working, the below ground parts of the working, and in particularly the the mine shaft(s) should not be adversely affected by plant equipment which has to be installed in them.

Mine workings with the characteristics enumerated in the introduction is known.

Above ground there is a cooling medium circuit in which a cooling medium is conducted between a compressor, a condenser, an expansion valve and an evaporator; various chemical fluids are used as the cooling medium. Dichlorodifluoromethane (CCl2F2) and Chlorodifluoromethane (CHCIF2) are particularly suitable for the operation of a refrigeration plant in a mine working. A condenser is also installed above ground in which the cooling medium, heated in the circuit, is condensed on pipes through which cooling water is flowing. For this cooling water, an open circuit is provided. Typically it passes to a cooling tower, which is set up above ground, and there loses waste heat to produce moist warm air. The evaporator of such a known plant also belongs to the parts of the plant which are located above ground.In the above ground evaporator, the liquid cooling medium is transformed into the vapour state. The heat required for evaporation is drawn from surfaces of pipes through which the stream of cooling medium is flowing. The cooling medium, cooled in this manner, flows through a closed circuit, the main sections of which pass under ground through one or more shafts. The cooling medium is therefore under the static pressure of the depth of the mine working and requires the provision of a high-pressure heat exchanger underground.

In the high-pressure heat exchanger, heat is extracted from the below ground second cooling medium circuit. This second cooling medium circuit is used to conduct away from the air cooler(s), heat extracted from air in the mine working. Generally, air coolers which have been specially constructed for underground operation are used, heat and moisture being extracted from the air in the mine working with the aid of a fan, the cold water being heated simultaneously. The medium in the second cooling circuit can also be used to cool a condenser in a direct evaporation system. In such a system, air from the mine working is passed, by means of a fan, through an air cooler in the form of an evaporator in which heat is extracted from the air by means of a cooling medium evaporating in coiled pipes over which the air passes in counter flow.The cooling medium circuit in such a system conducts the heat to a condenser from whence it is transferred to the medium in the second cooling circuit.

The invention relates to an air cooling plant in a mine working which eliminates the main disadvantage of the prior art arrangement.

The main disadvantage of prior art cooling plants lies in the restriction to a maximum cooling output which can be obtained with the plant. The maximum cooling output depends, in the main, on the thermal capacity of the said closed cooling medium circuit through which the cooling medium (e.g brine or water) is led from above ground to below ground and vice versa. In this closed cooling medium circuit the rate at which cooling medium can be circulated by economical means and the maximum possible temperature difference which can be tolerated in the circuit, determine its thermal capacity. Thus, for instance, a circuit with a circulation of water or brine of 110m 3/h and a temperature difference (AT) between outward and return flows of 20"C has a capacity of 2.2 Giga cal/h.The essential point is that for efficient operation of the above ground cooling units, which extract the heat from the cooling medium, the said AT in the riser shaft conduit cannot be much greater than 20"C. Use of the cooling units in the previously known plant therefore means a restriction to certain maximum temperature in the cooling medium circuit. On one hand the initial temperature of the cooling medium cannot be below freezing point if pure water is used. The lowest possible temperature which can safely be contemplated with pure water is 4 - 5"C. On the other hand, the maximum temperature of the cooling medium in the below ground second cooling medium circuit is also restricted. Maximum temperature of 25 - 28"C would be realistic.

The AT in the below ground cooling medium circuit is therefore restricted to approximately the same level, i.e. approximately 20"C.

These ratios are particularly disadvantageous when an installed plant has to be enlarged. This problem occurs relatively frequently when, for various reasons, the initial air cooling plant becomes too small for later operating conditions in the mine working.

For a long time, the practice has been to install a second plant, connected in parallel with the first, when increased thermal capacity is required. Normally, the installation of a separate circuit for the second plant in the shaft(s) of the mine, causes considerable difficulties.

It is therefore one aim of the present invention to achieve a considerable increase in the thermal capacity of the air cooling plant in a mine working (e.g. at least a doubling of it), without the closed cooling medium circuit which passes from above ground to below ground having to be supplemented by further duct work in the mine shaft(s).

According to the invention this aim is achieved by providing a second refrigerating plant located below ground and cooling said second refrigerating circuit by means of cooling medium flowing in the closed cooling medium circuit which passes from above ground to below aground.

Thus, in the closed cooling medium circuit which passes from above ground to below ground, the cooling medium can be passed below ground through one or more highpressure condensers after leaving the one or more high-pressure heat exchangers.

Because of this the cooling medium can be heated up to a higher temperature than hitherto, e.g. increased by a further 25 30 C., before it passes up the riser shaft conduit. The additional heat content in the cooling medium can be extracted from the cooling medium above ground. For this purpose, according to one embodiment of the invention, return cooling units installed above ground are used.

Using air cooling plant according to the invention makes double use of the shaft conduits, namely, to transport the cooling output of the above ground refrigerating below the ground, and to transport the condenser heat of the below ground second refrigerating unit above the ground.

Known return coolers can be used above ground for the initial cooling of the medium flowing up the riser shaft conduit. It is a particular advantage of the invention that the cooling medium flowing through the condenser of the below ground second refrigerating plant can be cooled directly by air or humidified air, since it is desirable, in heating technology, to transmit the enthalpy direct to the outside air.

Preferably, and according to another embodiment of the invention, provision is made for the evaporator of the below ground second refrigerating unit to receive cooling medium pre-cooled by the below ground high-pressure heat exchanger. In this way there is only one below ground cooling medium circuit and using pure water, temperatures in the region of 0 C can be employed in that situation. Under certain circumstances, this is of particular advantage when extending an existing air-cooling plant.

However, separate circuits for cold cooling medium can be associated with the highpressure heat exchanger and the evaporator of the below ground second refrigeration plant.

According to a further aspect of the invention there is provided a method of extending the air cooling plant of an underground mine working which method comprises adding a second refrigerating plant located below ground to the existing air cooling plant, said existing air cooling plant having a first closed cooling medium circuit passing from above ground to below ground and said existing air cooling plant comprising a first refrigeration plant connected in the said first circuit above ground and a heat exchanger connected in the said first circuit below ground and in which the said first cooling medium circuit is used for cooling a second cooling medium circuit installed below ground which supplies at least one air cooler installed in the mine working, the second refrigerating plant including a below ground condenser which is cooled by medium flowing in the said first closed cooling medium circuit, and a below ground evaporator feeding cooling medium to at least one further air cooler.

Further details and other advantages of the invention, will be found in the following description of one embodiment of the invention, given with reference to the accompanying block diagram.

In the closed circuit, given the general designation 1 and provided with flow arrows, the boundary between above ground and below ground is drawn in with a horizontal dashed line 2. An evaporator 4 of a cooling unit 18 is located above ground. The cooling medium (water or brine) passing through this evaporator and the said closed circuit 1 arrives first at a high-pressure heat exchanger 6 below the ground. This highpressure heat exchanger transmits to the cooling medium flowing in the closed circuit 1, heat from a cold water circuit given the general designation 7.In the cold water circuit 7 the water, according to the example shown, enters the high-pressure heat exchanger 6 at 270C and leaves it again at approximately 7"C. The cold water circuit 7 is installed underground and is used to operate air coolers or direct evaporators equipped with cooling medium circuits, which are installed in the mine working, particularly at the face. One of these air coolers is shown schematically at 8. Air from the mine enters the cooler 8, for example, at approximately 34"C and with a relative humidity of 80%. It leaves the air cooler 8 at a temperature of approximately 22"C and with approximately 95% relative humidity.

The initial temperature of the cooling medium in the closed circuit 1 of around 5"C is raised in the high-pressure heat exchanger 6 to around 25"C, according to the construction shown. The cooling medium at this temperature enters a high-pressure condenser 10 which belongs to a refrigerating plant given the general designation 11 and installed below ground. The high-pressure condenser conducts a cooling medium in a cooling agent circuit 12, the evaporator of which is shown at 13.The evaporator is used to cool a cold water circuit 14, which is operated with pure water, as is the cold water circuit 7, this water having an entry temperature into the evaporator of approximately 27"C and an exit temperature of approximately 7"C. The air coolers 15 (only one of which is shown) in the cold water circuit 14 are operated correspondingly, so that here, too, air at around 34"C and with approximately 80% relative humidity is cooled to approximately 22"C and 95% relative humidity.

The cooling medium, which acquires heat underground in the high-pressure condenser 10 of the refrigerating plant 11, leaves the high-pressure condenser 10 at approximately 50"C. Temperatures in the range 45" - 65"C, are possible. At this temperature the cooling medium arrives above ground and first enters a series-connected return cooler 16. In this return cooler the cooling medium is cooled from approximately 50"C to approximately 25"C. This is done with air or humidified air, the circuit of which is shown at 17. The heat is thus given up to the air above ground.

According to the example illustrated the cooling medium in the circuit 1, leaves the return cooler 16 at approximately 25"C and, still at this temperature, enters the evaporator 4 of the cooling unit 18. The evaporator 4 is correspondingly provided with a cooling medium circuit 19, in which a condenser 20 is connected. The condenser 20 is served by a cooling water circuit 21.

This cooling water is heated from an entry temperature of approximately 25"C to an exit temperature of approximately 35"C. A cooling tower 22 is used for re-cooling, and in turn releases moist warmed air above ground.

The plant described and illustrated can be produced by extending a basic plant which is shown in the left-hand part of the block diagram, the parts of the plant drawn in the right-hand part of the block diagram being additioned units used for such an extension.

Naturally, a plant as illustrated in the block diagram can be constructed in the illustrated form from the start, and it then has the advantage that from the beginning greater quantities of heat can be transported from below ground to above ground through a relatively small cooling medium circuit 1.

The system can be improved further by combining the cooling medium circuits 7 and 14 in a single circuit, and by conducting the cold water leaving the high-pressure heat exchanger 6 subsequently through the evaporator 13 of the below ground refrigerating unit. In this way, the exchange of heat can be improved both in the highpressure heat exchanger 6 and in the evaporator 13.

In addition, temperatures in the region of 0 C can be obtained in the below ground cooling medium circuit(s) 7 and 11 without using brine.

WHAT WE CLAIM IS: 1. An underground mine working comprising an air cooling plant having a closed cooling medium circuit passing from above ground to below ground, said air cooling plant comprising a refrigeration plant connected in the said circuit above ground and a heat exchanger connected in the said circuit below ground and in which the said cooling medium circuit is used for cooling a second cooling medium circuit installed below ground which supplies at least one air cooler installed in the mine working, and having a second refrigerating plant located below ground, which second refrigerating plant is cooled by medium flowing in the firstmentioned cooling medium circuit.

2. A mine working according to claim 1, in which a return cooler associated with the below ground second refrigerating plant is installed above ground in the said firstmentioned cooling medium circuit in series with an evaporator of the refrigerating plant installed above ground.

3. A mine working according to either of claims 1 or 2, in which the cooling medium flowing in a condenser of the below ground second refrigerating plant is cooled directly with air in a (or the) return cooler located above ground.

4. A mine working according to any preceding claim, in which an evaporator of the below ground second refrigerating plant receives cooling medium pre-cooled by the below ground heat exchanger of the refrigerating plant installed above ground.

5. A mine working according to claim 2 or any claim dependent on claim 2 in which the air cooling plant is operated such that the temperature of the cooling medium when it enters the below ground heat exchanger of the said first-mentioned cooling circuit is in the range 0 - 5"C and the temperature of the cooling medium as it leaves this below ground heat exchanger is in the range 20"C 25"C, the cooling medium entering a condenser of the below ground second refrigerating plant is at a temperature in the range 20"C - 25"C and leaves that condenser at a temperature in the range of 45"C - 65"C, the cooling medium enters the above ground return cooler at a temperature in the range 45 C - 65"C and leaves that return cooler at a temperature in the range of 24"C - 27"C, in which temperature range the cooling medium enters the evaporator of the refrigerating plant installed above ground, the cooling medium in a second medium circuit associated with the second refrigerating plant enters an air cooler of the second cooling medium circuit at a temperature in the range of 4 - 7"C and leaves that air cooler at a temperature in the range of 24"C - 27 C.

6. A mine working according to one of claims 1 to 5, characterised in that the below ground heat exchanger in the said firstmentioned cooling medium circuit and the below ground second refrigerating plant have separate cooling medium circuits associated with them, each employed for cooling different underground air coolers.

7. A method of extending the air cooling plant of an underground mine working which method comprises adding a second refrigerating plant located below ground to the existing air cooling plant, said existing air cooling plant having a first closed cooling medium circuit passing from above ground to below ground and said existing air cooling plant comprising a first refrigeration plant connected in the said first circuit above ground and a heat exchanger connected in the said first circuit below ground and in which the said first cooling medium circuit is used for cooling a second cooling medium circuit installed below ground which supplies at least one air cooler installed in the mine working, the second refrigerating plant including a below ground condenser which is cooled by medium flowing in the said first closed cooling medium circuit, and a below ground evaporator feeding cooling medium to at least one further air cooler.

8. An air cooling plant in an underground mine working substantially as hereinbefore described with reference to, and as illustrated in, the accompanying drawing.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (8)

**WARNING** start of CLMS field may overlap end of DESC **. of heat can be improved both in the highpressure heat exchanger 6 and in the evaporator 13. In addition, temperatures in the region of 0 C can be obtained in the below ground cooling medium circuit(s) 7 and 11 without using brine. WHAT WE CLAIM IS:

1. An underground mine working comprising an air cooling plant having a closed cooling medium circuit passing from above ground to below ground, said air cooling plant comprising a refrigeration plant connected in the said circuit above ground and a heat exchanger connected in the said circuit below ground and in which the said cooling medium circuit is used for cooling a second cooling medium circuit installed below ground which supplies at least one air cooler installed in the mine working, and having a second refrigerating plant located below ground, which second refrigerating plant is cooled by medium flowing in the firstmentioned cooling medium circuit.

2. A mine working according to claim 1, in which a return cooler associated with the below ground second refrigerating plant is installed above ground in the said firstmentioned cooling medium circuit in series with an evaporator of the refrigerating plant installed above ground.

3. A mine working according to either of claims 1 or 2, in which the cooling medium flowing in a condenser of the below ground second refrigerating plant is cooled directly with air in a (or the) return cooler located above ground.

4. A mine working according to any preceding claim, in which an evaporator of the below ground second refrigerating plant receives cooling medium pre-cooled by the below ground heat exchanger of the refrigerating plant installed above ground.

5. A mine working according to claim 2 or any claim dependent on claim 2 in which the air cooling plant is operated such that the temperature of the cooling medium when it enters the below ground heat exchanger of the said first-mentioned cooling circuit is in the range 0 - 5"C and the temperature of the cooling medium as it leaves this below ground heat exchanger is in the range 20"C 25"C, the cooling medium entering a condenser of the below ground second refrigerating plant is at a temperature in the range 20"C - 25"C and leaves that condenser at a temperature in the range of 45"C - 65"C, the cooling medium enters the above ground return cooler at a temperature in the range 45 C - 65"C and leaves that return cooler at a temperature in the range of 24"C - 27"C, in which temperature range the cooling medium enters the evaporator of the refrigerating plant installed above ground, the cooling medium in a second medium circuit associated with the second refrigerating plant enters an air cooler of the second cooling medium circuit at a temperature in the range of 4 - 7"C and leaves that air cooler at a temperature in the range of 24"C - 27 C.

6. A mine working according to one of claims 1 to 5, characterised in that the below ground heat exchanger in the said firstmentioned cooling medium circuit and the below ground second refrigerating plant have separate cooling medium circuits associated with them, each employed for cooling different underground air coolers.

7. A method of extending the air cooling plant of an underground mine working which method comprises adding a second refrigerating plant located below ground to the existing air cooling plant, said existing air cooling plant having a first closed cooling medium circuit passing from above ground to below ground and said existing air cooling plant comprising a first refrigeration plant connected in the said first circuit above ground and a heat exchanger connected in the said first circuit below ground and in which the said first cooling medium circuit is used for cooling a second cooling medium circuit installed below ground which supplies at least one air cooler installed in the mine working, the second refrigerating plant including a below ground condenser which is cooled by medium flowing in the said first closed cooling medium circuit, and a below ground evaporator feeding cooling medium to at least one further air cooler.

8. An air cooling plant in an underground mine working substantially as hereinbefore described with reference to, and as illustrated in, the accompanying drawing.