Surface preheater
The surface preheater is part of the boiler equipment of steam locomotives . It is used to preheat the boiler feed water with the exhaust steam and thus to increase the performance of the steam engine .
location
In standard locomotives, surface preheaters were always positioned across the chimney and were state-of-the-art in these locomotives; in new- build locomotives , they were replaced by the technology of the mixer preheater , in which the boiler feed water savings could be increased even further. Only locomotives with Riggenbach counter pressure brakes still had to be equipped with surface preheaters. The mixing nozzle on the mixing preheater would not have allowed the compressor function of the counter pressure brake to function properly.
The saving in boiler feed water was estimated at around 7.5% when using a surface preheater.
In addition to preheating the boiler feed water, surface preheaters were used to cool the ashtray .
Mode of action
The surface preheater works like a conventional heat exchanger . To preheat the boiler feed water, exhaust steam from the steam engine, which is branched off from the blowpipe , and from the auxiliary equipment operated with steam is used. At the lowest point of the surface preheater, the condensate is branched off and drained via a water separator and used to cool the ashtray.
This cycle is operated continuously. The other circuit in the surface preheater is started after the boiler feed pump is switched on. The water it sucks in from the tender is heated in the surface preheater at an evaporation temperature of around 100 ° C and passes through the boiler feed valve for processing in the steam locomotive boiler for evaporation. The surface preheater is designed in such a way that the exhaust steam is conducted through the inner pipes and the feed water is conducted past the pipes.
literature
- Manfred Weisbrod, Hans Müller, Wolfgang Petznick: Steam locomotive archive, series 01–99 , Transpress Verlag , Berlin 1976
Web links
- Website of the German Society for Railway History about the working principle of a surface preheater
Individual evidence
- ↑ The word part surface expresses that the heat flow from the steam to the (outer) surface of the tubes of the tube used heat exchanger is (indirect heat exchange) is made directed to the water in the pipes into it. In the case of steam boilers , the direction is reversed: the hotter flue gas is in the flue pipes , the water to be evaporated outside.
- ↑ Schematic representation of the mixer preheater on dlok.dgeg.de
- ↑ Internet site about feed water treatment on dlok.dgeg.de
- ↑ Photo of a cut open surface preheater in the repair shop on a private website
