Weather cooling machine

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A weather cooling machine is a machine that is used in mining for direct weather cooling of the mine workings . The primary task of the weather cooling machines is to cool the weather and lower the humidity. The pit climate is effectively improved through the use of weather cooling machines for cooling the weather and for supplying large amounts of weather .

history

The first refrigeration system was already running in the Brazilian mine Morro Velho in 1920. The system initially ran for several hours a day, from December of the same year the machine was in continuous operation. Initially, the machine generated an outlet temperature of 10 ° Celsius, and from December of the following year the outlet temperature could even be reduced to 6 ° Celsius. In the first half of the 20th century, the first surface cooler was installed underground at the Radbod colliery in Hamm to cool down the fresh weather . However, this installation did not bring the desired success. The reason for this was the insufficiently cold water from the Lippe , which was used as cooling water . After buying an ammonia refrigeration system from a brewery and integrating it into the system, this first refrigeration machine in the mining industry allowed the water to be cooled to such an extent that the system worked successfully. The pipe cooler installed underground cooled the weather passing by from 22 to 23 ° to up to 19 ° Celsius.

Basics

The cold generation in a weather cooling machine takes place according to the same principle as in a conventional air conditioning system . Depending on the design of the system, a distinction is made between direct and indirect weather cooling in the cooling process. With direct weather cooling, the weather is cooled directly by the evaporator . For this, the evaporator must be designed as a weather cooler. With indirect weather cooling, the weather is cooled indirectly via an intermediate water cycle. There are machines with above-ground cooling and machines with underground cooling. For large cooling capacities, combined machines with surface and underground cooling are also used. Whether the cold is generated above or below ground depends on several factors. The decisive factor here is primarily the size and performance of the cooling machine, but the distance from the pit to be cooled and the depth also play a major role in the location of the machine. The required cooling load is determined by the temperature prevailing on site. The transferable cooling capacity is determined by the weather conditions and the available weather current.

Cold production above ground

With this form of cooling, the cooling machines are installed centrally above ground. When the cooling machines are installed above ground, either the entire incoming air flow is cooled or only part of the air flow is cooled. The machine has a high pressure and a low pressure circuit. The high-pressure circuit is also referred to as the primary circuit, in which the refrigerant flows. A water-ethylene-glycol mixture or a lye is used as the coolant. The coolant is cooled by the evaporator and then pumped underground via an insulated pipe. The cold is transferred underground to the secondary circuit via a heat exchanger . However, there is also the option of separating the primary and secondary circuits using a pipe feeder . The cold is transported to the operating areas in the secondary circuit. With this form of cold generation, only partial weather flows are usually cooled. Above-ground cooling is well suited for large cooling capacities, with short distances to the operating point to be cooled and with lower depths. In the case of above-ground cooling, a large temperature spread in the cold water circuit of around 20 Kelvin is required. For this reason, it is advisable to connect several evaporators in series. In order that large cooling capacities can be transmitted over the smallest possible pipe cross-sections, it is necessary that the cold water supply temperature is very low.

Underground refrigeration

In the case of weather cooling machines installed underground, a distinction is made between central and decentralized cooling. Only water cooling sets are suitable for central cooling. Depending on the mining region, systems with screw compressors or, in deep pits, multi-stage turbo compressors are used. The cooling capacities of such systems are between 800 and 2200 kilowatts. The centrally installed weather cooling machines work in a similar way to weather cooling machines installed above ground. However, these machines do not have two circuits and therefore do not require a heat exchanger. The cold water circuit is directly coupled with the evaporator of the refrigeration machine. The cold water supplies the weather cooler with the required cooling water. In the case of the decentralized cooling machines, either machines with direct evaporators or machines with a water cooling circuit are used. The cooling capacities are between 100 and 300 kilowatts, depending on the machine. A special feature is the so-called cooling caterpillar. In this cooling machine, unlike the compact design, the cooling machine is divided into three units. This makes it easier to move the machine using an overhead monorail .

Weather cooler

Plate or strip tube coolers are used as weather coolers. The coolers usually work according to the counterflow principle. When it comes to weather coolers, a distinction is made between track coolers and face coolers. In the case of the line coolers, portable chambers with sheet steel housings are used for cooling capacities of up to 500 kilowatts. For larger cooling capacities, large spray chambers are installed in the lines . With these spray chambers, air cooling of up to 20 Kelvin is possible. Longwall coolers are at the face on longwall tanks attached. Special cooling surface designs are used for the face coolers. Here, heat sinks made of copper tubes with copper plates soldered on one or both sides are used. The cooling capacity of the face cooler is between 10 and 20 kilowatts. There are longwall coolers for direct weather cooling. These are movably installed in the face . A central component of all coolers is the fan. The fan is located on the upstream side of the cooler and pushes the sucked in weather through the cooler. The weather is cooled down accordingly. Since the weather thaws some of the air humidity when it cools down, there is a droplet separator on the outlet side of the cooler to drain away the dripping water. Due to the dust contained in the weather, the heat exchanger surfaces of the weather cooler quickly become dirty and must be cleaned at short intervals. The cleaning is carried out with an integrated pressurized water flushing device.

Weather cooling with ice

At greater depths of over 1500 meters, pressures of over 150 bar arise in the underground heat exchangers and in the pipes of the primary circuit . In addition, the cooling loads increase sharply at greater depths. Ultimately, this also leads to a disproportionate increase in the cost of the cooling systems. Already at the beginning of 1980 there were plans in the mines of South Africa to use ice as a coolant. Ice can absorb five times as much heat per unit of mass as water. There are different methods for cooling with ice. By using ice as a cooling medium in the primary circuit, the temperature in the secondary circuit can be reduced to almost zero degrees. With vacuum ice production, the pressure in the system is lowered below the triple point of water. With the supportive cooling, an ice slush is generated. This ice slurry is briquetted and the water present in the ice slurry is removed. The vacuum ice created in this way is fed into the mine building via pipes . The heat of fusion extracted from the ambient air ensures the necessary cooling in the corresponding pit rooms.

Individual evidence

  1. ↑ a b c d e Walter Bischoff , Heinz Bramann, Westfälische Berggewerkschaftskasse Bochum: The small mining dictionary. 7th edition, Verlag Glückauf GmbH, Essen 1988, ISBN 3-7739-0501-7 .
  2. ↑ a b Volker Schacke: Beginnings and development of weather cooling worldwide. In: Ring Deutscher Bergingenieure eV (Ed.): Bergbau, January 2008, pp. 17–21.
  3. ↑ Herbert Drost, Thomas Kessler. DSK mine Saar Schacht Primsmulde - central refrigeration system . In: Gussrohr-Technik Heft 42, pp. 72-77 Online  ( page no longer available , search in web archives )  Info: The link was automatically marked as defective. Please check the link according to the instructions and then remove this notice. (accessed on June 18, 2012; PDF; 199 kB).@1@ 2Template: Dead Link / 81.169.135.155  
  4. ↑ Reinhard Wesely: The development of weather technology and explosion protection in the early 20th century up to the mine accident at the Anna II hard coal mine in Alsdorf on October 21, 1930. In Anna Blatt No. 23, November 2005 Online ( Memento from July 26, 2015 in the Internet Archive ) (accessed on June 18, 2012; PDF; 1.2 MB).
  5. ↑ a b c d e f g h Heinz M. Hiersig (Ed.): VDI-Lexikon Maschinenbau. VDI-Verlag GmbH, Düsseldorf 1995, ISBN 9783540621331 .
  6. ^ A b c Carl Hellmut Fritzsche: Textbook of mining science. First volume, 10th edition, Springer Verlag, Berlin / Göttingen / Heidelberg 1961.
  7. ↑ a b c d e f g h i Karl-Heinrich Grote (ed.), Jörg Feldhusen (ed.): Dubbel paperback for mechanical engineering. Twenty-second revised and expanded edition, Springer Verlag, Berlin Heidelberg New York 2007, ISBN 978-3-540-49714-1 .
  8. ^ Jens H. Utsch: Efficient underground cooling with the "Pressure Exchange System". In: GeoResources Portal Manfred König (Ed.): GeoResources Zeitschrift, No. 2, Duisburg 2016, ISSN 2364-8414, pp. I – II, 47–50.
  9. ↑ a b Volker Schacke: Weather cooling with ice. In: Ring Deutscher Bergingenieure eV (Ed.): Bergbau, January 2009, pp. 17–21.

Web links

  • Reinholt Neukart: Junction of the East Mine - LARCH SHAFT . In: TS Bergbau, Online (accessed June 18, 2012; PDF; 181 kB)
  • P. Zbinden, A. Sala, Dr. Busslinger: Problems with air conditioning when driving and operating tunnels with high cover. Solution concepts for the Gotthard Base Tunnel online ( Memento from August 21, 2014 in the Internet Archive ) (accessed via Archive Org. On February 8, 2016; PDF; 180 kB)