Clean-Air Technology

Prevention, isolation and extinction of coal seam fires

The project participants deal with examination and isolation of coal seam fires in China and Mongolia. The subterranean fires release high quantities of CO2 and waste massive quantities of coal. Extinction could be financed through the CDM.

Summary

This sub-project is part of a collaborative project for prevention of coal seam fires. Coal seam fires are spontaneous subterranean fires that can occur when the coal comes into contact with oxygen. They produce high amounts of emissions and consume fossil fuel reserves. In northern China, they destroy up to 200 million tonnes of coal every year. Part A of the collaborative project examined combustion processes by means of laboratory analyses, model calculations and field measurements in order to facilitate parameter estimates of the material and energy consumption in coal seam fires. Part B intended to certify extinction activities via the Clean Development Mechanism established by the Kyoto Protocol. To this end, the degree needs to be calculated by which CO2 emissions are reduced when coal seam fires are extinguished. To this end, field research was conducted on fire propagation, crevasse and crack formation, temperature changes etc. in China and Mongolia. This was followed by the development of innovative extinction processes (methods for oxygen and heat deprivation, isolation of fire zones through barrier materials) and by design and installation of a heat pipe (heat sink) for ground cooling in a fire zone in Wuda (Mongolia).

Results:

  • Temperature-induced fracture zones affect not only the roof but also the floor; the seams located below a fire source may also be ignited. For a fire at a depth of H = 60 m, the primary normal stresses increase over a period of 20 years from 1.5 MPa to > 7 MPa without temperature influence or to > 15 MPa with temperature influence.
  • After deactivation of the heat pipe, the ground temperature in the immediate vicinity of the pipe increased from 45 to 75 K; no effect was discernible at a distance of 1.5 m. 
  • To prevent a fire from spreading, a combination of salt and vermiculite is recommended for achievement of both low heat conductivity and low permeability. These results can be applied to fire extinguisher additives.
  • Materials available on site (sand, gypsum, ash) are not suitable for use as barrier materials as they frequently contain arsenic (barrier materials are intended to block up crevasses upon setting and thus prevent egress of fumes and ingress of oxygen).

More Project Informations

Project title:  Verbundprojekt: Innovative Technologien für die Erkundung, Löschung und Beobachtung von Kohlebränden -Phase B- Koordination, Fernerkundung, Informationssystem

Project number:  0330490F, 0330490I, 0330490J

Project period:  2007 - 2010

Project region:  Germany (Bavaria, North Rhine-Westphalia, Saxony), China, Mongolia

Project contact:

Herr Dr.-Ing. Schmidt

Herr Dr. Wuttke

Herr Dr.-Ing. Fischer

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Source: German National Library of Science and Technology Hannover (TIB)