Tube dryer

from Wikipedia, the free encyclopedia
Removed tube dryer drums
Front center: Removed drum of a tube dryer in front of the Herrmannschacht briquette factory building

A tube dryer (also tubular barrel dryer , tube furnace or after its inventor also Schulz'scher dryer is called) an apparatus for drying of bulk materials . In principle, the dryer can be used for all free-flowing dry goods; Its main field of application is traditionally in the drying of ( brown ) coal dust in preparation for subsequent briquetting .

Structure and functionality

The dryer consists of a rotary tube , i. H. from a rotating, cylindrical container (drum), the axis of rotation of which is slightly inclined to the horizontal. The drum is closed at both end faces by a tube sheet . The two floors are connected in the axial direction by a large number of tubes - hundreds in the case of large dryers. From a bunker above the upper face of the drum, the material to be dried is fed into a template, the “filling box”. From here the material to be dried enters the tubes through the openings in the upper tube sheet and trickles through due to the inclination and rotation of the drum.

The closed drum is normally filled with water vapor from the inside ; H. the tubes are heated from the outside. When trickling through, the dry material comes into contact with the steam-heated walls of the tube (“ contact dryer ”) and the moisture contained in the material evaporates. In the case of lignite, the water content is reduced from around 50–60% in the raw state to around 10–20% after drying.

The steam is fed to the drum at the upper end via the hollow shaft and distributed over the shaft ("internal steam") and the drum shell ("external steam"). The resulting condensate is at the lower end in "suction boxes" collected by "swan-neck pipes" (similar to a sakia - Schöpfrad ) lifted to the shaft and removed it.

The rotation of the drum and thus the tubes loosens the drying material and reduces the risk of caking or clumping of the material as it trickles through, which would lead to the tubes becoming blocked. The flow behavior and the circulation of the dry material is supported by a spiral inside the tubes ("spiral bar"). The uniformity of distribution over the pipes can be improved by adding compressed air , but with combustible dry material such as lignite it must be taken into account that there is a risk of a dust explosion .

At the lower end of the tube, the material to be dried falls into a chute in the “ drop-out housing”. The evaporated moisture from the dry material ( vapor / steam ) also escapes into this housing. It is drawn off upwards via a chimney, and in a subsequent dedusting ( electrostatic precipitator , sifter ) residues of the dry material are separated from the vapor.

The largest tube dryers achieve production outputs of a little more than 20 t / h of dry coal.

history

The tube dryer was invented in the 1880s by civil engineer F. August Schulz. He developed the new type of dryer as an improvement on simple drum dryers . In 1884 Schulz applied for a patent for the new principle. The first prototype plant was built on behalf of the entrepreneur Hermann Gruhl and was in operation from 1885 in the drying service of a briquette factory in Bitterfeld in the central German lignite district . The tube dryer quickly spread from here to the other German lignite mining areas and over the next few years it replaced the previously dominant plate dryers in the lignite industry.

Inspired by the resounding success of the new dryer, Schulz, who had been director of Zeitzer Eisengießerei und Maschinenfabrik AG during the development of the dryer, started his own business in 1887. From then on, he cooperated closely with the Buckau machine factory , which from 1886, as a licensee of the Schulz patent, built numerous other dryers, and with Hermann Gruhl, who used the dryer type in his own briquette factory in the Gruhlwerk in the Rhenish district from 1892 .

To this day, tube dryers are used in coal refining plants in German lignite mining areas for the production of lignite dust and briquettes.

Historical specimens can u. a. can be visited in the museums of the briquette factory Louise and the briquette factory Knappenrode (both in the Lausitz district ) and in the Zeitz industrial museum Briquette factory Herrmannschacht (Central German district).

literature

  • Karl Kröll, Werner Kast: Drying and drying in production . Ed .: Otto Krischer (=  drying technology . Volume 3 ). 2nd Edition. Springer, 1989, ISBN 3-540-18472-4 .
  • H. Jordan: The tubular drum dryer from Schulz and its auxiliary devices . In: Glückauf . 1918, p. 701 .
  • Processing and use of lignite (=  specialist knowledge for lignite mining . Part II). Fachbuchverlag, Leipzig 1949.
  • D. Böcker, KJ Klöcker, HJ Klutz: Process for drying and grinding lignite . In: BWK . No. 44/78 , 1992, pp. 315 ff .

Individual evidence

  1. ^ Otto Lueger : Lexicon of the entire technology and its auxiliary sciences . tape  1 . Stuttgart / Leipzig 1920, p. 115–119 ( full text at Zeno.org).
  2. ↑ a b Bernd Thier (Ed.): Apparatus: Technology. Construction. Application . 2nd Edition. Vulkan-Verlag, 1997, ISBN 3-8027-2172-1 .
  3. ↑ a b c Kröll, pp. 520-521
  4. ↑ a b c d Gerd Lintzmeyer: Tube dryer: Technical data current after 1990. Accessed on September 3, 2012 .
  5. ↑ a b Frank Buschsieweke: Steam fluidized bed drying of brown coal . Institute for Process Engineering and Steam Boilers at the University of Stuttgart, 2006 ( full text as PDF [DNB] - dissertation).
  6. ↑ a b c d Business Field Finishing. (PDF; 3.2 MB) Presentation. RWE Power, accessed on September 3, 2012 .
  7. ↑ Ferdinand August Schulz (born September 8, 1841 in Parey ad Elbe ; † March 5, 1914 in Halle (Saale) )
  8. ↑ a b c Erich Rammler : Ferdinand August Schulz . In: Fuel Technology Society in the German Democratic Republic (ed.): 100 years of brown coal briquetting . VEB Wilhelm Knapp Verlag, Halle (Saale) 1958 ( excerpt ).
  9. ↑ Gerd Lintzmeyer: Machines and systems for lignite processing from Zemag Zeitz: tube dryer. Retrieved September 3, 2012 .
  10. ↑ German Reich Patent No. 32220 of December 19, 1884
  11. ^ Gustav Kloos:  Gruhl, Hermann Eduard. In: New German Biography (NDB). Volume 7, Duncker & Humblot, Berlin 1966, ISBN 3-428-00188-5 , p. 208 ( digitized version ).