Weather cooling
As air cooling is referred to in the mining the cooling part flows weather by means of technical devices and machines. Targeted cooling of the weather makes it possible to enable or facilitate the work of miners in heavily heated mine structures.
Basics
The rock temperature increases by one degree at certain intervals due to the geothermal depth. The high rock temperatures also warm the weather. In Rhine Westphalian coal district, the temperature further increases due to the temperature-enhancing layer of marl , 100 meters layer of marl here, the temperature rises to an additional three degrees. At a depth of 725 meters with a 200 meter thick layer of marl, this leads to a rock temperature of 35 ° Celsius. In some areas, there is an unusually high increase in temperature with increasing depth due to the host rock. A further increase in temperature can arise in coal mining due to the self-heating of coal seams . All of this means that from a certain depth the weather temperature is so high that the miners working there are exposed to climatic stress .
History
Problems with high weather temperatures arose in civil engineering as early as the 19th century . At a mine in the Washoe Mining District there was an unusually high temperature increase in the rock temperature at a depth of 500 meters. Since this mine in an area mined in the nearby jungvulkanisches surrounding rock was located, the rock temperature rose because of the prevailing low Geothermal depth level to values of up to 87 degrees. Due to these high rock temperatures, weather temperatures of 43¾ degrees came up even with strong weather movements. In mines with less weather, the temperature rose to 50 to 65 degrees. But the penetration of mining into ever greater depths and the associated increase in temperature led to major problems in some mines around the world at the end of the 19th century .
Cooling methods
A first possibility to lower the weather temperature is to increase the amount of weather . However, an increase in the amount of weather is simultaneously associated with an increase in the speed of the weather . With this method you quickly reach the limit of what is feasible. Another method to cool the weather down is to spray finely divided water in the incoming air stream. The water evaporation in the dry air leads to a decrease in the air temperature. The weather temperature drops by 1.9 ° C if the air absorbs one gram of water per cubic meter. However, the cooling of the weather leads to an undesirable saturation of the air with water vapor. Ultimately, this means that the cooling effect of the air is not significantly improved. If the water has a significantly lower temperature than the weather stream, the air is still cooled immediately by the water. This effect is better, the greater the temperature difference between water and air and the greater the amount of water used. This principle is used by installing water showers. These water showers can significantly reduce the weather temperature.
Another method of cooling the weather temperature is by blowing out compressed air. This escapes from machines or specifically from jet nozzles. This outflowing dry and cold compressed air can be completely added to the weather flow or directed to an operating point via pipelines. The compressed air works in two ways. Due to the dry compressed air, the humidity in the weather is reduced. By mixing with the cool compressed air, the weather temperature drops at the same time. Another method of cooling the weather is the use of natural ice. This method was practiced in American mines and in the Simplon Tunnel . The stream of weather in the area of the resting stations was cooled with blocks of ice that were placed in large barrels.
A method was used at the Radbod and Westphalia mines in which partial flows of the weather were kept cool by means of heat protection agents. In individual stretches , ducts were laid on the floor for ventilation. These ducts were embedded in slag wool or sawdust to isolate the air in the ducts. This method enabled a significant cooling effect to be achieved on site. Another method was used at the Sachsen and Radbod collieries . Here, in stretches where the weather was particularly hot, cladding was installed on the roofs and joints . The space between the rock and the casing was filled with fly ash or sawdust. With this method, the temperature increase of the weather stream in a 260 meter long straightened section could be reduced from six degrees to one degree. In order to achieve even better weather cooling, the use of weather cooling machines is necessary.
literature
Ludwig Motzko: Cold and warmth in earth and air . Manzsche Verlagbuchdruckerei, Vienna 1947
Individual evidence
- ^ A b Walter Bischoff , Heinz Bramann, Westfälische Berggewerkschaftskasse Bochum: The small mining dictionary. 7th edition, Verlag Glückauf GmbH, Essen 1988, ISBN 3-7739-0501-7 .
- ↑ a b c Fritz Heise, Fritz Herbst: Textbook of mining science with special consideration of hard coal mining. First volume, published by Julius Springer, Berlin 1908
- ↑ a b c d e Volker Schacke: Beginnings and development of weather cooling worldwide. In: Ring Deutscher Bergingenieure eV (Ed.): Bergbau, January 2008, pp. 17–21.
- ↑ a b c d e f Fritz Heise, Fritz Herbst: Textbook of mining studies with a special focus on hard coal mining. First volume, fifth improved edition, published by Julius Springer, Berlin 1923.
- ↑ Albert Serlo: Guide to mining science. Second volume, 4th improved edition, published by Julius Springer, Berlin 1884.
- ^ A b c d Carl Hellmut Fritzsche: Textbook of mining science. First volume, 10th edition, Springer Verlag, Berlin / Göttingen / Heidelberg 1961.