A cornertube boiler is a type of natural circulation water-tube boiler which differentiates itself from other water tube boilers by its characteristic water-steam cycle and a pre-separation of heated steam from the steam-water mixture occurs outside the drum and the unheated downcomers.[1]


Cornertube boilers were developed for small steam output. The design was based around two factors that, along with excellent water circulation, should be appropriate cooling even at light loads. Its special feature is its Monocoque body i.e. the unheated downcomers form the supporting frame work[2] and not the thermally loaded tubes, hence the name corner tube boiler.[1] Moreover, the piping-arrangement (system) is also responsible; to manage the riser tubes and water distribution in riser tubes and down comers and to collect the steam water mixture and to make a certain amount of pre-separation of steam and water mixture.[3][4] Put simply, the water circulation takes place simultaneously through the drum and through the unheated down comers outside the drum.[5]


During World War II a shortage of fuels like gas and petrol alongside the idea of running diesel engines with Steam occurred and led to the development of a new type of boiler.[6] Dr. Henrich Vorkauf came up with the first design of a new natural circulation boiler which was then installed into a truck in the year 1944.[2] Using this principle Dr. Vorkauf developed a single drum boiler with downcomers in four corners and named this boiler Eckrohrkessel (German name). Corner Tube Boiler is word to word translation of Eckrohrkessel (Eck=Corner, rohr=tube and kessel=boiler).


Schematic working of water circulation in corner tube boiler

The water flows down from the drum (6) through the down comers (7) and it is distributed in the different riser tubes(4). The steam-water mixture circulates and flows in the upward direction through the riser tubes. In the radiation heated area through the pre-separator (also known as cross-collector) (3) occurs the pre-separation of steam from the steam water mixture. The separated steam flows through the overhead pipe (5) and the steam-water mixture flows through the collector pipe (3) to the drum (6) as well. In the drum occurs the final separation of steam from steam water mixture. The rest amount of water flows through the unheated return tubes (1) and downcomers (7) to the rear wall distributor/header (2). Due to the water returning from the unheated downcomers (1) a lively circulation takes place .[7]




The various fuels which can be used or are commonly used in the US, Europe and Pacific Countries are Bagasse, Biomass, Lignite, Coal, Scaly Bark, Fuel gas, Industrial waste, Khuff gas, MFO (marine fuel oil), Organic matter, Oil, Litter, Rice hulls, Rubberwood, Sludge, Wood, Woodchips.[6]


  1. ^ a b c d e Thome-Kozmiensky, Karl J. (1994). Thermische Abfallbehandlung. Germany: EF für Energie und Umwelttechnik. pp. 393–394. ISBN 3-924511-77-2.
  2. ^ a b c Mayer, Fritz (1986). The Corner Tube Boiler. Germany: Resch. p. 99. ISBN 3-87806-033-5.
  3. ^ Block, F; Lalone, Girouard, Letendere (May 1977). "Designing a Boiler for Waste Fuels". Power. USA: 75.((cite journal)): CS1 maint: multiple names: authors list (link)
  4. ^ Josefsson, Lars. "Eckrohr Boiler". Steam Esteem. Retrieved 11 March 2013.
  5. ^ Vorkauf, Henrich (1957). Der Wasserumlauf in Eckrohrkessel. Germany: Energie. p. 3.
  6. ^ a b Noot, Wolfgang (2011). Vom Kofferkessel bis zum Großkraftwerk Die Entwicklung im Kesselbau (in German). Germany: Vulkan Verlag. p. 345. ISBN 978-3-8027-2558-6.
  7. ^ Vorkauf, Henrich (1951). "Der Eckrohrkessel". VDI Zeitschrift. 93 (14): 395–397.
  8. ^ Peterseim J.H., White, S., Tadros, A., Vanz, E. (2012). Pre-feasibility study for a multi-fuel / concentrated solar power hybrid plant at Swanbank, QLD. Prepared for Thiess Services Pty Ltd by the Institute for Sustainable Futures, University of Technology, Sydney, Australia.21-25.