Pit fan

Impellers of an axial two-stage pit fan with adjustable blades

As mine fans are called in mining fans that the ventilation of a mine are.

Basics

Radial pit fan with diffuser

To ensure that the underground mines are adequately supplied with fresh air, it is usually necessary that the weather change (exchange of the used air) is carried out automatically. When the weather is blown into the mine workings by the weather machine, one speaks of weather blowers, when the weather is sucked into the mine workings, one speaks of weather suction. By compressing the fresh weather, weather blowers create an overpressure, by means of which the fresh weather is driven into the mine workings. A vacuum cleaner creates a negative pressure by diluting the air, thereby sucking the weather out of the mine and consequently sucking the fresh weather into the mine. Depending on the installation location of the pit fan, a distinction is made between section fans and main pit fans. Main pit ventilators are located near an extending weather shaft . These fans are equipped with a diffuser to improve the fan efficiency . Route fans supply routes that are not in the continuous flow of weather with fresh weather via a duct .

Lineup

Pit fan of a US mine

The main pit fans can be installed either above or below ground. Which installation variant is chosen depends on various factors. As a rule, the above-ground installation is preferred, since the underground installation is often associated with higher costs. The maintenance of fans above ground is also easier to carry out. However, the additional expense for sealing the manhole opening is disadvantageous in the case of installation above ground. If the extending ventilation shaft is also used for conveying , the underground installation of the fan offers certain advantages. So you can z. B. dispense with the above-ground airtight closure of the shaft opening for underground installation.

drive

Pit fans were powered in different ways. Small hand-operated weather drums were used for ventilation in the Freiberg mining area. For example, there was a weather drum that had been developed by the head art master Schwamkrug. This was equipped with a hand crank and a gear reduction gear and was used to ventilate smaller mine workings. This fan could be used both as a vacuum cleaner and as a weather blower. In the Harz mining industry, a pit ventilator was used to improve weather management, which was driven by an artificial wheel with a chain drive. The artificial wheel had a diameter of eleven meters and generated an output that was 2.5 times that of a hand-operated fan. At the end of the 19th century, mine fans were also powered by electricity . Small pit fans were equipped with direct current motors . These motors had outputs of up to 47 kilowatts and could move up to 65 cubic meters of air per minute. Larger pit fans were equipped with a three-phase motor that delivered up to 80 kilowatts. These engines had to be started with liquid starters . Today's main pit fans have outputs of over 2500 kilowatts. Compressed air-operated section fans are also used in specially weathered sections. There are also combinations of compressed air and electric drives. These section fans are driven by a three-phase motor in normal operation; if the power supply fails, the compressed air motor switches on automatically until the electric motor runs again.

Speeds

Pit fans are designed in such a way that their peripheral speed does not become too great. The aim is circumferential speeds of around 30 meters per second. Smaller fans with a diameter of up to four meters are built as high-speed fans. Fans that have a larger impeller diameter are operated as low-speed fans. The Schwamkrug weather drum was designed for speeds of up to 1000 revolutions per minute. Today's main pit fans are operated at speeds of 400 to 500 revolutions per minute.

Amount of weather

Each pit ventilator can, depending on the design, bring a certain amount of weather into the pit. As early as the 19th century, large mine fans were able to move over 2500 cubic meters of air per minute. Today's modern pit ventilators are able to move over 22,000 cubic meters of air. The amount of weather that a fan can move is also dependent on the width of the pit. Large pit fans are suitable for large pit widths, smaller pit fans are better suited for small pit widths. From a certain pit size, the amount of weather that a single fan can generate is no longer sufficient. There is then the option of having two fans connected in parallel, i.e. next to each other, sucking through the same duct. Another variant is to install the two pit fans on different shafts. Both fans must be constantly monitored so that they do not influence each other. Another possibility is to connect the fans in series. With this variant, however, the drive machines require more power than if they were running individually.

literature

H. Hoffmann, C. Hoffmann: Textbook of mining machines (power and work machines). 3rd edition, Springer Verlag OHG, Berlin 1941.

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 .
↑ Explanatory dictionary of the technical terms and foreign words that occur in mining in metallurgy and in salt works and technical articulations that occur in salt works. Falkenberg'schen Buchhandlung publishing house, Burgsteinfurt 1869.
^ Heinrich Veith: German mountain dictionary with evidence. Published by Wilhelm Gottlieb Korn, Breslau 1871.
^ ^A ^b Gustav Köhler: Textbook of mining history. 6th edition, published by Wilhelm Engelmann, Leipzig 1903.
↑ Julius Ritter von Hauer: The weather machines . Published by Arthur Felix, Leipzig 1889.
^ Julius Weisbach: Textbook of engineering and machine mechanics. Third part, The mechanics of intermediate and working machines, printed and published by Friedrich Vieweg and Son, Braunschweig, 1851.
↑ Wilfried Ließmann: Historical mining in the Harz. 3rd edition, Springer Verlag, Berlin and Heidelberg 2010, ISBN 978-3-540-31327-4 .
^ Wilhelm Brüsch: Guide to electricity in mining. Printed and published by BG Teubner, Leipzig 1901.
↑ ^a ^b ^c Industrial fans ( Memento from February 15, 2010 in the Internet Archive ) (PDF; 4.1 MB) (accessed via Archive Org. On January 14, 2016).
^ Carl Hellmut Fritzsche: Textbook of mining science. First volume, 10th edition, Springer Verlag, Berlin / Göttingen / Heidelberg 1961.
↑ ^a ^b The book of inventions trade and industry. Fifth volume mining and metallurgy, publishing and printing by Otto Spamer, Leipzig 1899.
↑ Albert Serlo: Guide to mining science. Second volume, 4th edition, published by Julius Springer, Berlin 1884.
↑ Fritz Heise, Fritz Herbst: Textbook of mining science with special consideration of hard coal mining. First volume, published by Julius Springer, Berlin 1908.

Web links

Drive of a pit ventilator (last accessed on June 6, 2016)
Fan building and diffuser (last accessed on June 6, 2016)
Mine ventilators in parallel operation at shaft 5 of the Radbod colliery (last accessed on June 6, 2016)
Pit fan of the Feggendorfer tunnel (last accessed on June 6, 2016)

[Quelle_1-1] 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 .

[Quelle_4-2] Explanatory dictionary of the technical terms and foreign words that occur in mining in metallurgy and in salt works and technical articulations that occur in salt works. Falkenberg'schen Buchhandlung publishing house, Burgsteinfurt 1869.

[Quelle_8-3] Heinrich Veith: German mountain dictionary with evidence. Published by Wilhelm Gottlieb Korn, Breslau 1871.

[Quelle_2-4] A ^b Gustav Köhler: Textbook of mining history. 6th edition, published by Wilhelm Engelmann, Leipzig 1903.

[Quelle_3-5] Julius Ritter von Hauer: The weather machines . Published by Arthur Felix, Leipzig 1889.

[Quelle_10-6] Julius Weisbach: Textbook of engineering and machine mechanics. Third part, The mechanics of intermediate and working machines, printed and published by Friedrich Vieweg and Son, Braunschweig, 1851.

[Quelle_9-7] Wilfried Ließmann: Historical mining in the Harz. 3rd edition, Springer Verlag, Berlin and Heidelberg 2010, ISBN 978-3-540-31327-4 .

[Quelle_11-8] Wilhelm Brüsch: Guide to electricity in mining. Printed and published by BG Teubner, Leipzig 1901.

[Quelle_5-9] Industrial fans ( Memento from February 15, 2010 in the Internet Archive ) (PDF; 4.1 MB) (accessed via Archive Org. On January 14, 2016).

[Quelle_6-10] Carl Hellmut Fritzsche: Textbook of mining science. First volume, 10th edition, Springer Verlag, Berlin / Göttingen / Heidelberg 1961.

[Quelle_7-11] The book of inventions trade and industry. Fifth volume mining and metallurgy, publishing and printing by Otto Spamer, Leipzig 1899.

[Quelle_12-12] Albert Serlo: Guide to mining science. Second volume, 4th edition, published by Julius Springer, Berlin 1884.

[Quelle_13-13] Fritz Heise, Fritz Herbst: Textbook of mining science with special consideration of hard coal mining. First volume, published by Julius Springer, Berlin 1908.