Pulverized coal engine

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The pulverized coal engine was a reciprocating piston engine , which - instead of liquid fuel - was operated with about 4  µm fine coal dust . The pulverized coal engine, designed as a diesel engine , the development of which was intensively promoted in Germany from 1916 to 1940, was a mistake.

Beginnings

As early as 1824, Nicolas Léonard Sadi Carnot mentioned coal dust as a possible combustion material in the cycle . In 1851 a type of "pulverized coal turbine" is mentioned in a US patent, and in 1880 J. Wickfeld registered a patent for a pulverized coal engine. In 1899 Rudolf Diesel experimented with a pulverized coal engine , Paul Meyer described the experiments:

"I think it was done with a soup spoon, adding a portion of coal dust, and [...] I can still remember that after about 5 minutes the joke was over. The coal dust had seized all the piston rings and was blown through between the wall and the piston. [...] The machine required two days of cleaning work, and then the attempt was repeated again in front of a high commission with the same success. "

- Paul Meyer

Diesel's colleague Rudolf Pawlikowski (1868–1942) advocated its development with great personal and material commitment. In 1916 Pawlikowski brought the pulverized coal engine to work for the first time, the converted stationary MAN diesel engine developed 80  hp . The Rupa engine named after the acronym Pawlikowski was u. a. Further developed by IG Farben and MAN from 1925 to 1930 and by various machine factories in Germany until 1940. IG Farben invested several million Reichsmarks in developing the pulverized coal engine.

Functionality and undesirable development

A four-stroke engine working on the diesel principle generates a negative pressure in the combustion chamber via the piston in the first stroke. An auxiliary pump simultaneously creates a negative pressure in an antechamber with coal dust. In the second cycle, the auxiliary pump pushes the coal dust out of the antechamber into the combustion chamber via the inlet valve.

The combustion process in the pulverized coal engine has always been problematic. The coal dust had to be of a constant fineness, not allowed to clump together and had to ignite itself at the right time. A decisive factor in the failure of the pulverized coal engine was the system-related wear of the liner due to the abrasive effect of the pulverized coal in the cylinder, which was 500 times that of a diesel engine. “After 150 hours of operation, a cast iron bushing with a diameter of 420 mm achieved a wear of 7 mm at the top dead center of the piston.” The amount of ash and slag produced was also calculated to be 5-10 percent of the combustion material, even with optimal combustion. How to remove these from the cylinder has been the subject of various patent specifications.

“The pulverized coal engine can serve as a teaching example that [...] an unsuitable concept, no matter how much intellectual and material effort, cannot be implemented successfully [...]. For this undesirable development, which was foreseeable from the start, large amounts of money were literally squandered. "

Further experiments with coal dust

In 1978 General Motors developed the prototype of a pulverized coal-fired gas turbine that powered the Cadillac Eldorado . The Federal Association of the German Aerospace Industry then applied to the Federal Ministry of Research and Technology for research funding for the development of a pulverized coal engine, which the Federal Minister did not approve.

literature

  • Stefan Zima, Reinhold Ficht: Unusual engines. 3rd edition, Vogel-Buchverlag, Würzburg 2010, ISBN 978-3-8343-3140-3 .

Individual evidence

  1. ↑ a b c Hans-Joachim Braun: A failed attempt at innovation. The pulverized coal engine. (PDF; 7.3 MB) Deutsches Museum, Munich 1982.
  2. ↑ J. Wickfeld's rel. A. Bernstein's pulverized coal engine. In: Polytechnisches Journal . 256, 1885, pp. 482-484.
  3. ↑ Coal engine . adac.de; accessed on August 23, 2013.
  4. ^ Paul Meyer: Contributions to the history of the diesel engine. Julius Springer Verlag, Berlin 1913, p. 32. (quoted from Zima / Ficht)
  5. ^ Rudolf Pawlikowski in the German biography
  6. ↑ a b c Zima / Ficht, pp. 563-565.
  7. ↑ Hans Wahl: Combating wear and tear in dust engines . In: ZVDI , 89, 1936, p. 1099 - quoted from Zima / Ficht ( memento of the original from August 31, 2013 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. . @1@ 2Template: Webachiv / IABot / www.vautid-verschleiss-technik.de
  8. ^ Hugo Güldner: The design and calculation of internal combustion engines. Julius Springer Verlag, Berlin 1903, p. 142.
  9. ↑ Stefan Zima / Reinhold Ficht, p. 563 f.
  10. ^ Coal in Your Stocking? Fuel Up the Cadillac! In: New York Times , 2009; accessed on August 23, 2013.
  11. ^ German Bundestag, 8th electoral term, 230th session. July 4, 1980 (PDF; 3.5 MB).