Title:
Method of cooling the air in underground mine workings and like places
United States Patent 2386560


Abstract:
1-2 Claims. (Cl. 62 --i0) This invention relates to an improved method of cooling the air in underground mine workings and is particularly applicable to deep mines where high temperatures are the rule. According to an earlier application it is proposed positively to evacuate dust-laden air...



Inventors:
Flodden, Lunt William Richard
Application Number:
US31861340A
Publication Date:
10/09/1945
Filing Date:
02/12/1940
Assignee:
Flodden, Lunt William Richard
Primary Class:
Other Classes:
62/172, 62/260, 62/401, 62/524, 165/45, 165/175, 454/172
International Classes:
E21F3/00
View Patent Images:



Description:

1-2 Claims. (Cl. 62 --i0) This invention relates to an improved method of cooling the air in underground mine workings and is particularly applicable to deep mines where high temperatures are the rule. According to an earlier application it is proposed positively to evacuate dust-laden air from .mine workings by means of -a suction .conduit system arranged to extend from the surface to the underground shafts and working places. The said conduit system branches in all directions throughout the mine and each branch is provided at spaced intervals with valve-controlled openings which openings are arranged at the lower points or depressions in the workings towards which the dust particles normally tend to gravitate. The means at the surface for creating a partial vacuum in the conduit system may comprise an evacuating pump or the like.

Accordingly the present invention consists in the provision of-a suction conduit system tending from the-surface to the underground shafts and working places, means -at the surface for evacuating air from said conduit .system so as to create a partial vacuum therein, means in-, the form of restricted resistance-creating inlet' apertures to cause 'controlled adiabatic expansion of the constant entropy or isentropic process type, of the mine air into the conduit system to cool it -and utilising the conduit system as heat exchanging means to extract heat from the mine ' air in contact therewith, whereby the- workings bYe cooled by air drawn .from the bottom -or lower levels upwardly. By mine air is meant the air in the shaft or drives surrounding-the con--dtit system, and which is available to the- workers. By exhaust air, as the term is hereinafter employed in-the specification and claims, I mean the Vitiated mine air as it is -drawn from the mine exteriorly of the conduit :systum, into the conduit system and is there subjected to a -sequence ofthermal processes.

Moreý particularly it is proposed to insert in the, cbiduit system large expansion -chambers whereby, -due to the -drop in temperature caused by the :adiabatic expansion of the air -entering the chambers, cooling 'of the mine air .surrounding and p-assig in 'contact with said -expansion -chaitberts i-effected by a transfer of heat from the mine :air -to the ait being evacuated.

These expansion chambers 'are provided at n- 50 expansion purposes. tervals ithroughout the conduit system and at positiOns in th-e ine workings where they will be most teffective in cooling the-mine -at. The said chambtes are provided with -large.-cooling_ surfaces to ensiure the maximum transferof-.heat.

It will be; understood that the drop in temperature through adiabatic expansion, will also take place in the ducting forming the conduit system,--and this ducting will be constructed and .S arranged in such a manner that it acts effectively to assist cooling the mine air. According to the method of the present invention air in the underground workings of a mine is cooled by heat exchange with air drawn from the bottom or lower 0 e) -levels upwardly in contradistinction to known methods where cooling is effected by heat exchange with air drawn from the surface -downwardly.

In applying the invention it is proposed that, where a series of pipes converge, incoming air is arranged to pass around the piping for purposes of being cooled.

According to present practice dust-laden air is withdrawn from mine workings by means of exex-r0 -haust trunking ,which terminates in the mine workings in, dust-collecting chambers.

According to the present invention control valves and heat: exchangers are. suitably interspersed -on all exhaust trunking -extending from 5 these dust-collecting chambers. so that -the adiabatic expansion of the mine- air as it. passes through these-passages will give a degree ofoeoling which is tlhs communicated to the mine air.

On all exisi-tingmine -ventilation systems of the suction type, control -valves, Venturi -ducts and like -means for- reducing- or throttling the air flow are employed to cause a slight degree of expansion and so give a cooling effect. Suction . heads or filtering heads may or may: not be con-5 tained in a suctionexhaust system, in-cases where valves are- in existence -for controlling the air inflow.

On all -existing exhaust onduits eff-ective 'heat extraction may be increased by, painting -such 0 coneduits black a-nde providing them -with -ins.

The-exhaust -trunking is further iprovided with reducing air intake apenttrres where required for :aontrolling air expansion. -Such apertures are preferably in the form of replaceable nozzles.hav5 ing a -streamlined interior shape -to reduce triction losses.

Airresistance by means offilteringand suction heads may be -created in the ,uction system ,so as intentionally to -restrict the fflow fof air for The air expansion chambers or heat exchangers included in .a suction system are provided -with means for extracting .condensed -moisture which is liable to collect -therein. ,Such means may '55 consist .of water-collecting chambers provided with the necessary stop cocks or valves for isolating such chambers for drainage purposes.

In order to increase the degree of suction in the dust-collecting chambers air ejectors operating from the existing compressed air conduit may be employed. Fans may be embodied in the exhaust conduit not so much as boosters but as means to localise the vacuum effect or sub-atmospheric pressure for air expansion purposes.

The invention also includes the provision in existing or new ducting of a valve or valves arranged for automatic opening or closing whereby intermittent expansion of air is obtained. The said valve or valves may be arranged to be controlled thermostatically or their opening 7and closing may be arranged to depend upon the degree of suction or velocity of the air entering the ducting. In the first mentioned arrangement a thermostatic device such as a bimetallic strip may be employed, while in latter case spring tension or the speed of a wind vane located in the duct may be used.

When thermostatically operated, full opening of the valve or valves may be arranged to take place when the mine temperature rises to a certain degree, which will cause a decrease in temperature in the mine air and the removal of a larger quantity of air with little expansion, or alternatively a rise in mine temperature may be arranged to cause a partial opening of the valve or valves whereby the expansion will be greater but the removal of air lessened. In this latter case, owing to the volume of air removed being reduced, the British thermal units extracted will of course be lessened and the temperature of the workings will rise.

In an alternative embodiment an electrically operated vibrator valve governed by an electrically operated governor of the ball type may be employed in such a manner that its speed would control the valve for opening and closing the duct as desired.

It is to be understood that the present invention is applicable to existing ventilation systems as well as to new installations.

To enable the invention to be more clearly understood and carried into practice, reference is now made to the accompanying drawings in which like reference numerals denote like parts throughout the several views.

Figs. la-ld illustrate diagrammatically applications of the invention to the underground workings of a mine.

Fig. 2 is an elevation of an improved construction for the ventilation ducting.

Pig. 3 is an end section taken on line III-III of Fig. 2.

Fig. 4 is an elevation of an expansion chamber or heat exchanger.

Fig. 5 is an elevation of a modified construction of expansion chamber or heat exchanger.

Pig. 6 shows a spring-regulated control valve.

Fig. 7 shows a thermostatically-controlled valve.

Fig. 8 shows a modified form of thermostatically controlled valve.

Fig. 9 shows a valve controlled for intermittent opening and closing by electrical means, and Fig. 10 shows a valve controlled by the degree of suction or velocity of inflow of mine air.

Referring to the drawings, Fig. la, reference I denotes a branch of the suction ducting extending down a shaft 3 into an underground working 2. One inlet for mine air is shown at 4.

A suction is created by pump 55 disposed on the surface of the ground. The mine air entering by this opening is restricted or throttled by the Venturi throat 5 whereafter it expands into the expansion chamber or heat exchanger 6, provided with fins 7 to increase its efficiency.

In Figure lb a slightly different form of heat exchanger is shown at 8. In this case the opening 9 causes throttling of the inflowing mine air by being made relatively smaller than the chamber 8. To provide means for controlling the degree of partial vacuum in the chamber 8, a booster fan or blower 10 is arranged in series with the ducting I. A vacuum gauge 11 indicates the degree of vacuum being obtained.

In Figure Ic alternatively a nozzle 50 controlled by a valve or cock 51 may be used to control expansion of mine air into the suction conduit I which will itself then act as heat exchanging means.

In another embodiment shown in Figure Id a filtering head 53 controlled by a valve 54 may be arranged so that the fitlering medium provides sufficient resistance to inflow to cause the entering mine air to expand for purposes of cooling the suction conduit I.

To facilitate the transfer of heat, the suction ducting may be constructed in the manner shown in Figs. 2 and 3, in which the walls are corrugated or fluted in a longitudinal direction to increase their effective area.

Fig. 4 illustrates one form which an expansion chamber or heat exchanger may take. As shown it is connected to the suction ducting by the pipe 12 while the inlet apertures for the mine air are shown at 13 and 14. Valves 12a, 13a and 14a are provided to regulate the rate of inflow and outflow and consequently the degree of cooling obtained. Vacuum gauges 15 and 16 indicate the actual degree of vacuum at the inlet and outlet sides respectively. The vertical pipes 17 and 18 are connected by a series of horizontal smaller bore cross pipes 19 provided with fins 20. The 45 lower ends of the pipes 17 and 18 lead into a duct and moisture-collecting chamber 21 supplied with drain cocks 22. The isolating valves 23 and 24 are provided to enable the chamber to be drained when necessary.

Fig. 5 illustrates another form which a heat exchanger may take. In this case vertical pipes 25 and 26 are connected by small bore cross pipes 27 and top and bottom pipes 28 and 29.

The bottom pipe 29 constitutes the dust- and moisture-collecting chamber and for this purpose is provided with the drain cocks 30. Mine air enters by the aperture 31 and the apparatus is connected to the suction ducting by the pipe 32 controlled by the valve 33. A valve 34 conStrols the inlet aperture 31.

Figs. 6 to 10 illustrate various constructions to provide for the automatic opening and closing of valves controlling the inflow of mine air to the suction ducting 40. In Fig. 6 a valve 35 is arranged to be opened against the action of a compression spring 36. In Fig. 7 a valve 37 is arranged to be opened thermostatically by expansion of the heat sensitive coil 38. In Fig. 8 a butter-fly valve 39 is controlled thermostatically by a heat sensitive spiral 41. In Fig. 9 a butterfly valve 42 is arranged to be opened intermittently by an electrically operated vibrator coil 43, co-operating with a contact 44 fixed to an arm 45 actuating the valve 42. And lastly, Fig.

S10 shows a gate valve 46 controlled by a governor 47 actuated by a wind vane 48 located in the .adting 40. IThese constructions are given by way of :example iand are not intended to limit ithe inventijn to these :particular methods ,of "Ialve ontrol.

Whj t Iclaim is:L In localizing "the cooling of -air prevailing at selected places in the drives in a mine working which working includeh s a .main ;shaft and drives extending therefror, the :nethod which comprises, in combinatihn, the steS 'of drawing a atrnam of exaust air from the drives into a principal Zo ' of lower presstre through lranch 2on-es located i4a Said drives and discharging the air -from said pinicipal zone utside ofthe said .workAn-g, tranisfr-.ng heat:froai and 'reducing the temperatue of the air prevailing -in said selected places by causing the stream of exhaust air in 'each branch zone to undergo a cnrtroll'ed -adia-batiC expansiBn -adjacen:t each selected place, "and causing heat exchange, while said exihaust air is cooled as a result of such expansion, -betweeh the air prevailing in such selected place and the cooled and iexpanded 'exhaust air in the 'particular branch zone associated therewith.

'2. An improved method of cooling the air in an uinditground working, comprising drawing, -through a suction- ventilating conduit systenm dis:posed in said working, a- 'partial vacuum from the region of the outlet of said working and thereby, at selected points in the working, -and by said :vacuum, drawing the air into said condiUt system, and expanding it, in a controlled Adiabatic process, thereby readcing the tem-perature of the air, and, at selected points 'within said working, facilitating heat transfer from the air exteriorly of the conduit system to the expanded and -cooled air within the latter, to cool said exterior air.

3. An improved ~iethod of cooling the air in an underground workiing having an opening or oatlet to the surface, comprising -drawintg, through a suction ventilating conduit system disposed in said working and having one or -more heat -exchange zones disposed at desired points therein, a partial vacuum from the region of said outlet, thereby at selected points in the working, and by -said vacuum, drawing the air into 'said conduit system, and expanding it, in a -controlled adiabatic process, through restricted stream-lined openings, in said conduit system on the upstream side -of said zone or zon'es, 'and, at said one or more heat-exchange zones, facilitating heat trasfer -from the air exteriorly of the -conduit system to the expanded and cooled air within the latter, to cool said exterior air.

4. Apparatus for cooling the air in an underground working; having an opening or outlet to the surface of the ground, comprising a conduit system extending from said outlet into said working; air-evacuating means connected thereto near said outlet for evacuating exhaust air from the system so as to create a partial vacuum in the system; one or more heat-exchange means provided in said conduit system at a point or points within the working where it is desired to localize the cooling of the air in said working exterior to said conduit system; and means, having stream-lined interiors, and providing openings on the up-stream side of said heat exchange means, for causing a controlled adiabatic expansion of the air drawn therethrough into the said heat exchange means, thereby appreciably lowering the temperature of the air which is being exhausted, the heat-exchange means serving to transfer the heat of the air exterior thereto, and which contacts :them, toi thre exianded and o.bled air -blig exhausted.

5. Apparatus for c''ling the air in an 'nder-ground -working -having an opening or outlet to '5 'the surface of thie ground, -omprising a tcnduit system extending frdo said outlet into said working; ainrevacuating means tconnected thereto near said outlet for evacuating exhaust air from the'system,:so-as to create apartial Vacuum there:10 in:; one or more :heat-exchange imeans provided in said conduit system at -a point or points within the working Where it is desired to localize the -cooling of the air in said working exterior to said conduit system, said heat-exchange means hav-15 ing total cross-sectional areas substantially increased over that of the :remainder of the coniuit :system, and having large surface areas, for active heat transfer; and means, having streamlined interiors, sand providing openings on the ý:'0 up-stream side of said heat-exchange means, for " causing a Controlled 'adiabatic expansion of the air drawn therethrough into the said heat-exChange means, thereby appreciably lowering the temperature of the air which is being exhausted, :2 the heat-exhange means :serving to transfer"the heat of th air exterior thereto, and which eontacts them, to the expanded :and cooled aif being exhausted.

6. Applaratus for. cooling .the air in an under80 gground Working, having an opening or outlet to the :surface of the groiud, comprising a conduit system extending from said outlet into said working; air-evacuating means bconnected thereto-near -said outlet for eVaccating exhaust air fromi the system, -so as to create a partial vacuum in the Systen; one or more heat-exchange means Provided in said conduit system at a point bor poits within the working where it is desired to localize the cooling Of the tir in -said Working exterior to the' cbnduit system, said heat-exchange megns having total 'coss-sectional areas substantially :increased 6 eer that of the remainder of the conduit sygtfem, and having large surface area, tfor active heat transfer; water-collecting "chainbrs 5 .hconected to said heat-exchahge means for ecllecting c6ndensed moisture; means for isolating said chambers from the rest of the tsystem, to permit drainage; and means, having stream-lined interibrs, and providing openings 'on the upstream side of said heat-exchange meieans. for causing a controlled iadiabatie expansidnh f the air drawn- therethrough into the said heat-ox'ithange imeans, thereby apprediably lowering the tem~perature of the air which is being exhaksted, the heat-exchange means serving to tffatsfert:he het 'of the itr exterior thereto, and which contacts themfi, t the -expainded :and coled ai t 'iihg exhausted.

7. Apparatus for cooling the air in an underground working, having an opening or outlet to the surface of the ground, comprising a conduit system extending from said outlet into said working; air-evacuating means connected thereto near said outlet for evacuating exhaust air from the system, so as to create a partial vacuum in the system; one or more heat-exchange means provided in said conduit system at a point or points within the working where it,is desired to localize the cooling of the air in said working exterior to said conduit system; means, having stream-lined interiors, and providing openings on the up-stream side of said heat-exchange means, for causing a controlled adiabatic expansion of the air drawn therethrough into the said heat-exchange means, thereby appreciably lowering the temperature of the air which is being exhausted, the heat-exchange means serving to transfer the heat of the air exterior thereto, and which contacts them, to the expanded and cooled air being exhausted, and booster fans in the conduit system for substantially localizing the vacuum effect at desired points.

8. Apparatus for cooling the air in an underground working, having an opening or outlet to the surface of the ground, comprising a conduit system extending from said outlet into said working; air evacuating means connected thereto near said outlet for evacuating exhaust air from the system, so as to create a partial vacuum in the system; said conduit system being externally modified at one or more points along its length within the working substantially to localize the heat transfer from the neighboring air in said working exterior to said system; and means, having streamlined interiors, providing openings on the up-stream side of the modified portion or portions of said conduit system, for causing a controlled adiabatic expansion of the air drawn therethrough into the said modified portion or portions of the conduit system, thereby appreciably lowering the temperature of the air which is being exhausted, the modified portion or portions of the conduit system serving to transfer the heat of the air exterior thereto, and which contacts it, to the expanded and cooled air being exhausted.

9. Apparatus for cooling the air in an underground working, having an opening or outlet to the surface of the ground, comprising a conduit system extending from said outlet into said working; air-evacuating means connected thereto near said outlet for evacuating exhaust air from the system, so as to create a partial vacuum therein, one or more heat-exchange means having exteriorly disposed heat-absorbing fins provided in said conduit system at point or points within the working where it is desired to localize the cooling of the air in said working exterior to said conduit system; and means, having stream-'45 lined interiors, and providing openings on the upstream side of said heat-exchange means, for causing a controlled adiabatic expansion of the air drawn therethrough into said heat-exchange means, thereby appreciably lowering the tem-( perature of the air which is being exhausted, the heat-exchange means serving to transfer the heat of the air exterior thereto, and which contacts them, to the expanded and cooled air being exhausted. 10. Apparatus for cooling the air in an underground working, having an opening or outlet to the surface of the ground, comprising a conduit system extending from said outlet into said working; air-evacuating means connected thereto near said outlet for evacuating exhaust air from the system, so as to create :a partial vacuum therein; one or more heat-exchange means exteriorly black in color provided in said conduit system at point or points within the working where it is desired to localize the cooling of the air in said working exterior to said conduit system; and means, having stream-lined interiors, and providing openings on the up-stream side of said heat exchange means, for causing a controlled adiabatic expansion of the air drawn therethrough into the said heat-exchange means, thereby appreciably lowering the temperature of the air which is being exhausted, the heatexchange means serving to transfer the heat of the air exterior thereto, and which contacts them, to the expanded and cooled air being exhausted.

11. An improved method of cooling the air in an underground mine working comprising drawing, through a suction ventilating conduit system disposed in said working, a partial vacuum from the region of the outlet of said working and thereby, at selected points in the working, and by said vacuum, drawing the atmospheric air and its existing water vapour content into said conduit system, and expanding said air, in a controlled adiabatic process, thereby reducing the temperature of the air, and at selected points within said working, facilitating heat transfer from the air exteriorly of the conduit system, to the expanded and cooled air within the latter, to cool said exterior air.

12. Apparatus for cooling the air in an underground working, having an opening or outlet to the surface of the ground, comprising a conduit system extending from said outlet into said working; air-evacuating means connected thereto near said outlet for evacuating exhaust air from the system so as to create a partial vacuum in the system; one or more heat-exchange means provided in said conduit system at a point or points where it is desired to localize the cooling of the air in said working exterior to said conduit system; and means for causing a controlled adiabatic expansion of the air drawn therethrough into said heat exchange means, thereby appreciably lowering the temperature of the air which is being exhausted, the heat-exchange means serving to transfer the heat of the air exterior thereto, and which contacts them, to the expanded and cooled air being exhausted.

WILLIAM R. F. LUNT.