1、 PDF外文：http:/ 2860 字 出处： Fire technology, 2007, 43(4): 285-300 英文原文 Recent Developments and Practices to Control Fire in Undergound Coal Mines S. K. Ray* and R. P. Singh, Central Mining Research Institute, Barwa Road, Dhanbad, Jharkhand 826 001, India Abstract: Co
2、al mine res cause serious threat to the property and human lives. Out-break of re may 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
3、 of Goaf, Water mist etc. The paper addresses all those control techniques in detail. 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 techniqu
4、es like Infusion of liquid nitrogen, Injection of high pressure high stability nitrogen foam, and Water mist on open re are also discussed. Keywords: coal mine re, reversal of underground mine ventilation, nitrogen foam, inertisation of goaf & water mist 1. Introduction Since inception, mi
5、ning is considered as a most hazardous and dangerous of peacetime activities. An outbreak of re in the underground 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
6、 is also there. It affects to both persons working underground at the time of the outbreak and to those 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)
7、 res resulting from spontaneous combustion of coal (b) open res, which are accidental in nature, caused as a result 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
8、 airways, loose and fallen coal in the goaf area, electricity, mechanical friction, blasting, welding, explosions and 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 commenc
9、e from a single point of ignition) and to study the effectiveness of various re suppression techniques viz., liquid nitrogen, high pressure high stability nitrogen foam and water mist, recently Central Mining Research Institute, Dhanbad, India has designed and constructed a Mine Fire Model Gallery.
10、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 m2. 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
11、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 regulation 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 telemonitori
12、ng system. The system consists of 130 sensors (98 temperature, 25 gas, 3 pressure, 2 heat ux, 1 each velocity and Suspended Particulate Matter (SPM) concentration sensor) and instruments with data logger, computer, computer peripheral etc. for continuous monitoring of various re parameters like gas
13、concentration (O2, CO2, CO, CH4 & H2), air velocity, pressure across re zone and fan pressure, temperature, heat ux, dust and particulate matter concentration inside the gallery. Figure 1 Isometric view of mine re model gallery Details of the construction of the gallery and i
14、ts 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 10.5 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 K
15、enda 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 paper addresses all the above control measures that have been applied all over the world. Results of experimentation on open res
16、 in Mine Fire Model Gallery are also discussed. 3.Fghting Mine Fires 3.1 High Pressure Foam Use of foam plugs has been successful in ghting mine res in roadways where direct attack with water is not possible. USBM studies reveals that the water content of the foam should not be less than 0.20
17、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 appear to be effective against deep seated, rapidly advancing, buried or dead end res. In India, suppression of spontan
18、eous 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 mined out areas of longwall panels. The foam is produced by high pressure foam generator under the pressure of 10 foaming
19、 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 consists of two independent units namely pumping unit and foam generating unit. The foam is produced from a mixture
20、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 to the foam-generating unit at a minimum pressure of 0.2 MPa, mixed with foaming mixture sprayed from nozzles and th
21、en 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 transported 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 by the coal as the foam forms a thin
