煤矿火灾控制的最近发展和实践外文文献翻译.docx

1、煤矿火灾控制的最近发展和实践外文文献翻译英文原文Recent Developments and Practices to Control Fire in Undergound Coal MinesS. K. Ray* and R. P. Singh, Central Mining Research Institute, Barwa Road,Dhanbad, Jharkhand 826 001, IndiaAbstract: Coal mine res cause serious threat to the property and human lives. Out-break of re m

2、ay be dealt with advanced re suppression techniques like Infusion of inert gases or liquid nitrogen, Dynamic Balancing of pressure, Reversal of under-ground mine ventilation, Application of nitrogen foam, Inertisation of Goaf, Water mist etc. The paper addresses all those control techniques in detai

3、l. Success story of controlling res in coal mines of different parts of the world are reported. Results of a recently completed Science & Technology (S&T) project with regard to various re suppression techniques like Infusion of liquid nitrogen, Injection of high pressure high stability nitrogen foa

4、m, and Water mist on open re are also discussed.Keywords: coal mine re, reversal of underground mine ventilation, nitrogen foam, inertisation of goaf & water mist1. IntroductionSince inception, mining is considered as a most hazardous and dangerous of peacetime activities. An outbreak of re in the u

5、nderground workings of a mine poses a direct threat from the re itself. Further, an invisible and immediate threat from carbon monoxide poisoning and an explosion, particularly in gassy coal mines is also there. It affects to both persons working underground at the time of the outbreak and to those

6、involved in the subsequent rescue and re ghting. It hampers the coal production and sometimes loss of coal winning machinery. Fires in coal mines may be categorised into two groups viz.,(a) res resulting from spontaneous combustion of coal (b) open res, which are accidental in nature, caused as a re

7、sult of ignition of combustible materials.In coal mines, res are generally caused due to several reasons viz., sluggish ventilation, high pressure difference across intake and return airways, loose and fallen coal in the goaf area, electricity, mechanical friction, blasting, welding, explosions and

8、illicit distillation of liquor.2. Mine Fire Model Gallery To understand the complex dynamic phenomenon of open res (res that occur in mine airways usually commence from a single point of ignition) and to study the effectiveness of various re suppression techniques viz., liquid nitrogen, high pressur

9、e high stability nitrogen foam and water mist, recently Central Mining Research Institute, Dhanbad, India has designed and constructed a Mine Fire Model Gallery. The model gallery is 65.5 m long; arch in shape with a base of 2.4 m and crown height of 2.7 m. The cross section of the gallery is 5.86 m

10、2. The gallery is divided into ring and non-ring zones. An exhaust type axial ow fan having a capacity to deal with 25 m3/s. of air quantity at 50-mm wg pressure has been installed at its end. The gallery is provided with two sliding doors for quick sealing of the re and a rolling shutter for regula

11、tion of desired airow. An isometric view of mine re model gallery is shown in Figure 1.It is equipped with a state-of-the-art computer aided on-line telemonitoring system. The system consists of 130 sensors (98 temperature, 25 gas, 3 pressure, 2 heat ux, 1 each velocity and Suspended Particulate Mat

12、ter (SPM) concentration sensor) and instruments with data logger, computer, computer peripheral etc. for continuous monitoring of various re parameters like gas concentration (O2, CO2, CO, CH4 & H2), air velocity, pressure across re zone and fan pressure, temperature, heat ux, dust and particulate m

13、atter concentration inside the gallery.Figure 1 Isometric view of mine re model galleryDetails of the construction of the gallery and its instrumentation system have beendescribed elsewhere In the experiments inner side of the ring zone of the gallery which is 22 m in length (ring zone starts from 1

14、0.5 m from the entry of the gallery) was lined with a thin layer of coal slabs, 810 cm thick, brought from Dobrana seam of New Kenda Colliery. Fixing of coal slabs were effected with a mixture of air setting cement and liquid binder. In each set of experiments about 1820 tons of coalswere used.The p

15、aper addresses all the above control measures that have been applied all over the world. Results of experimentation on open res in Mine Fire Model Gallery are also discussed.3.Fghting Mine Fires3.1 High Pressure FoamUse of foam plugs has been successful in ghting mine res in roadways where direct at

16、tack with water is not possible. USBM studies reveals that the water content of the foam should not be less than 0.20 kg/m3 otherwise the foam is not capable of controlling the re. With sucient ventilating forces (around 8 cm wg) properly generated foam may be transported over 300 m. Foam does not a

17、ppear to be effective against deep seated, rapidly advancing, buried or dead end res.In India, suppression of spontaneous heating by high pressure high stability foam is a new and effective method. However, the method has been widely used in Czech mines in controlling spontaneous heating of the mine

18、d out areas of longwall panels.The foam is produced by high pressure foam generator under the pressure of 10 foaming gas. The produced foam is transported by pipelines or re hoses to the re area. Inert gas (N2, CO2), compressed air or a combination of both is used as foaming gas. The foam generator

19、consists of two independent units namely pumping unit and foam generating unit. The foam is produced from a mixture consisting of water and 5% foaming agent. This mixture is pumped by a pumping unit into a foam-generating unit where the foam is produced . At the same time inert gas (N2) is supplied

20、to the foam-generating unit at a minimum pressure of 0.2 MPa, mixed with foaming mixture sprayed from nozzles and then passes through a ne mesh installed inside the foam generation unit. At the outlet of the foaming unit a re resistant hosepipe of suitable diameter is attached by which the foam is t

21、ransported to the place of infusion. A schematic diagram for HPHS nitrogen foam generation system is shown in Figure 3.The foam helps in controlling the spontaneous heating in following manner. Reducing air leakage through mined out area Reducing temperature Reducing the rate of sorption of oxygen b

22、y the coal as the foam forms a thinprotective lm over the coal. Pumping Unit400 V, 50 Hz5%mixture Fire Hose Foam to FireAffected Areaof water &foaming agent Foam Generating Unit Figure 3 Set up for injection of high-pressure high stability nitrogenHigh pressure nitrogen foam has recently been used i

23、n AW1 longwall panel of 1 & 2 Incline mine of Jhanjra project, ECL with very encouraging results. In this mine foam was injected in the longwall goaf through boreholes. A trolley mounted PSA type nitrogen generator having a capacity of 300 Nm3/h. was used. High pressure high stability nitrogen foam

24、(HPHS) is cheap (one kg of foaming agent capable of producing 2 m3 of foam costing about 2.1 $) and has long self life. The HPHS nitrogen foam at a rate of 200 m3/h has been applied during experimentation in CMRI Mine Fire Model Gallery to control open re.The following points are worth mentioning.It

25、 has been observed from the results that there was substantial reduction in temperature. The average value of this reduction in temperature has been found to be 207C per hour.After infusion of foam in open re condition the concentration of all the Products of Combustion (POC) like CO2, CO, CH4 and H

26、2 has decreased, indicating the retardation of combustion process.On infusion of foam, reduction of generation rate of CO2 and CO is estimated as 80% and 85%, respectively.High-pressure high stability nitrogen foam technology proved to be promising to control open res. However, 200-m3/h infusion rat

27、e was found inadequate to suppress the re completely.3.2. Water MistWater can be used in mines either in the form of spray or mist. McPherson (1993) mentioned that once a re has been progressed to a fuel rich condition thereis little chance of extinguishing without sealing off the re. He does, howev

28、er, suggest that a means available to gain control of the re by the application of water as a natural scale fog.Water mist refers to ne water sprays in which 99% of the volume of the spray is in droplets with diameter less than 1,000 l. Water mist re suppression systems (WMFSSs) are readily availabl

29、e, simple in design and construction, easy to maintain, effectual in suppressing various res, non-toxic, and cheaper than other familiar re suppressing system with no harmful environmental impact.While applied in re areas, it cleans the air by dissolving soluble toxic gases produced during combustio

30、n, washing down smoke and suppressing dust, and thus improves visibility as well. Unlike many other re ghting systems, WMFSSs can be safely used in manned areas and found to be effective in open condition. Furthermore, water consumption in WMFSSs is far less than that in water ushing, spraying or sp

31、rinkling systems. On account of these advantages, much study has been carried out in recent years to develop appropriate WMFSSs to control various types and size of res.A survey carried out in 1996 indicated that nearly 50 agencies around the world were involved in the research and development of WM

32、FSSs, ranging from theoretical investigations into extinguishing mechanisms and computer modeling to the development, patenting and manufacturing of water mist generating equipment . Water mist is being evaluated for the suppression of res in diesel fuel storage areas in underground mines at National Institute for Occupational Safety and Health (NIOSH), Pittsburgh. Water mist has shown a positive impact to control a fuel-rich duct re 30 when a series of experiments on water mist was carried out in a 30 cm square, 9 m lon