287:. The steam is then passed through a number of superheater elements, which are long pipes placed inside the larger diameter fire tubes, called flues. Hot combustion gases from the locomotive's fire pass through the flues and, as well as heating the water in the surrounding boiler, they heat the steam inside the superheater elements they flow over. The superheater element doubles back on itself so that the heated steam can return. Most do that twice at the fire end and once at the smokebox end, so that the steam travels a distance of four times the header's length while being heated. At the end of its journey through the elements, the superheated steam passes into a separate compartment of the superheater header and then to the cylinders of the engine.
459:, which caused pitting and subsequent weakening of the superheater elements. Leakage of gases was also commonplace between the elements and the header, and maintenance was difficult without removal of the horizontally-arranged assembly. The Robinson version suffered from temperature variations caused by saturated and superheated steam chambers being adjacent, causing material stress, and had similar access problems as the Schmidt type.
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A separately fired superheater is a superheater that is placed outside the main boiler and has its own separate combustion system. This superheater design incorporates additional burners in the area of superheater pipes. It is rarely, if ever, used because of its poor efficiency and the fact that the
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A superheater increases the distance between the throttle and the cylinders in the steam circuit and thus reduces the immediacy of throttle action. To counteract that, some later steam locomotives were fitted with a front-end throttle, placed in the smokebox after the superheater. Such locomotives
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Without careful maintenance, superheaters are prone to a particular type of hazardous failure, involving the superheater tubes bursting at their U-shaped turns. They are difficult to manufacture, and to test when installed, and a rupture causes the superheated high-pressure steam to escape into the
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The report's recommendations enabled Urie to design a new type of superheater with separate saturated steam headers above and below the superheater header. They were connected by elements beginning at the saturated header, running through the flue tubes and back to the superheater header, and the
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The steam passing through the superheater elements cools their metal and prevents them from melting, but when the throttle closes that cooling effect is absent, and so a damper closes in the smokebox to cut off the flow through the flues and prevent them being damaged. Some locomotives,
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intervened before the trials could take place, although an LSWR Locomotive
Committee report from late 1915 noted that the Robinson version returned the best fuel efficiency. It consumed an average of 48.35 lb (21.9 kg) coal per mile over an average distance of 39,824 mi
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The main advantages of using a superheater are reduced fuel and water consumption but there is a price to pay in increased maintenance costs. In most cases the benefits outweighed the costs and superheaters became widely used, although
British shunting locomotives
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can sometimes be identified by an external throttle rod that stretches the whole length of the boiler, with a crank on the outside of the smokebox. That arrangement also allows superheated steam to be used for auxiliary appliances, such as the
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Superheater viewed from the smokebox. Top centre is the superheater header, with pipes leading to cylinders. Tubes below feed steam into and out of the superheater elements within the flues. The stack and the damper have been removed for
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will make more efficient use of steam energy than a reciprocating engine. However, saturated ("wet") steam at boiling point may contain, or condense into, liquid water droplets, which can cause damage to turbine blades. Therefore,
304:, which admitted air to the superheater when the locomotive was coasting. That kept the superheater elements relatively cooler and the cylinders warm. The snifting valve can be seen behind the chimney on many LNER locomotives.
321:. Another benefit of the front-end throttle is that superheated steam is immediately available. With a dome throttle, it takes some time before the super heater actually provides an efficiency benefit.
156:. There are three types of superheaters: radiant, convection, and separately fired. A superheater can vary in size from a few tens of feet to several hundred feet (a few metres to some hundred metres).
455:
However, the report stated that both superheater types had serious drawbacks. The
Schmidt system featured a damper control on the superheater header that caused hot gases to condense into
389:
using saturated steam and those fitted with the
Schmidt superheater between October 1907 and March 1910, proving the advantages of the latter in terms of performance and efficiency.
381:, believed that the Schmidt type could be bettered, and the design and testing of an indigenous Swindon type was undertaken, culminating in the Swindon No. 3 superheater in 1909.
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locomotive, with an early form of superheater, was built in 1898, and more were produced in series from 1902. The benefits of the invention were demonstrated in the UK by the
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4-6-0 locomotives. In anticipation of performance trials, eight examples were fitted with
Schmidt and Robinson superheaters, and two others remained saturated. However,
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452:(64,090.5 km), compared to 48.42 lb (22.0 kg) and 59.05 lb (26.8 kg) coal for the Schmidt and saturated examples respectively.
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whole assembly was vertically arranged for ease of maintenance. The device was highly successful in service, but was heavy and expensive to construct.
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engines typically superheat the steam, usually within the primary boiler, to ensure that no liquid water enters the system and damages the blades.
476:) were rarely fitted with superheaters. In locomotives used for mineral traffic the advantages seem to have been marginal. For example, the
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A radiant superheater is placed directly in the radiant zone of the combustion chamber near the water wall so as to absorb heat by radiation.
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locomotive with a superheater, is the Bh.1 owned by
Steiermärkische Landesbahnen (STLB) in Austria, which runs excursions trains on the
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use, by far the most common form of superheater is the fire-tube type. That takes the saturated steam supplied in the dry pipe into a
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A convection superheater is located in the convective zone of the furnace, in the path of the hot flue gases, usually ahead of an
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Allcock, N.J.; Davies, F.K.; le
Fleming, H.M.; Maskelyne, J.N.; Reed, P.J.T.; Tabor, F.J. (June 1951). White, D.E. (ed.).
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large flues, back to the fire and into the locomotive cab, creating extreme danger for the locomotive crew.
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of the steam engine, and have been widely adopted. Steam which has been superheated is known as
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A simplified diagram of a coal-fired thermal power station. The superheater is the element 19.
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Robert Urie's design of superheater for the LSWR was the product of experience with his
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The oldest surviving steam locomotives with a superheater, as well as being the first
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Technique for increasing the temperature of steam to improve steam engine efficiency.
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656:. London: London, Railway Correspondence and Travel Society, 1974. pp. 88–93.
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quality of the steam produced is no better than that from other superheater types.
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or wet steam. From the early 20th century, superheaters were applied to many
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The
Locomotives of the Great Western Railway, part one: Preliminary Survey
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General arrangement of a superheater installation in a steam locomotive.
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carried out a series of comparative tests between members of his
172:. A convection superheater is also called a primary superheater.
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Locomotives of the London
Brighton & South Coast Railway, 3
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The first practical superheater was developed in Germany by
214:, the superheater further heats the steam generated by the
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Locomotives with superheaters are usually fitted with
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56:. Unsourced material may be challenged and removed.
377:(GWR) in 1906. The GWR Chief Mechanical Engineer,
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361:in 1910 of steam locomotive with a superheater
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226:inside the engine. Superheaters increase the
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550:Herbert Rauter, Günther Scheingraber, 1991:
357:Early color photograph from Russia taken by
222:and decreasing the likelihood that it will
140:or dry steam. Superheated steam is used in
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392:Improved superheaters were introduced by
116:Learn how and when to remove this message
665:. Didcot Oxon: Wild Swan Publications.
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283:mounted against the tube sheet in the
234:, and non-superheated steam is called
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337:, because it is difficult to keep a
54:adding citations to reliable sources
480:fitted superheaters to some of its
663:LSWR Locomotives: The Urie classes
527:"How a steam railway engine works"
14:
487:but later began to remove them.
422:Southern Railway (Great Britain)
410:London and South Western Railway
369:during the 1880s and 1890s. The
298:London and North Eastern Railway
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41:needs additional citations for
943:Internally rifled boiler tubes
439:Urie's "Eastleigh" superheater
1:
19:For the physics process, see
513:www.pleasley-colliery.org.uk
467:Advantages and disadvantages
132:is a device used to convert
152:, and in processes such as
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18:
554:. Hermann Merker Verlag,
291:Damper and snifting valve
248:power generating stations
193:In many applications, a
1050:Steam boiler components
661:Bradley, D. L. (1987).
652:Bradley, D. L. (1974).
562:(in German), pp. 85-88.
414:Eastleigh railway works
402:Gorton locomotive works
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359:Sergey Prokudin-Gorsky
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250:throughout the world.
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146:electricity generation
912:Electric water boiler
907:Electric steam boiler
638:Bradley (1987), p. 16
624:Bradley (1987), p. 15
478:North Eastern Railway
424:, also at Eastleigh.
398:Great Central Railway
375:Great Western Railway
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345:at high temperature.
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831:Babcock & Wilcox
296:particularly on the
50:improve this article
485:mineral locomotives
433:Mur Valley Railroad
383:Douglas Earle Marsh
300:, were fitted with
987:Boiler peripherals
823:Water-tube boilers
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308:Front-end throttle
281:superheater header
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228:thermal efficiency
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136:or wet steam into
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926:Boiler components
765:Fire-tube boilers
240:steam locomotives
232:superheated steam
218:, increasing its
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379:G. J. Churchward
277:steam locomotive
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246:in electrical
244:steam turbines
220:thermal energy
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181:Steam turbines
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533:on 2008-12-21
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509:"Superheater"
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67: –
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65:"Superheater"
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61:Find sources:
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39:This article
37:
33:
28:
27:
22:
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999:Boiler water
948:Safety valve
938:Fusible plug
876:Thimble tube
662:
653:
646:Bibliography
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573:
567:
551:
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535:. Retrieved
531:the original
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512:
503:
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470:
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454:
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429:narrow gauge
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391:
371:Prussian S 4
364:
349:Applications
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212:steam engine
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48:Please help
43:verification
40:
21:superheating
1024:Superheater
978:Water gauge
836:Corner tube
482:NER Class P
449:World War I
406:Robert Urie
339:slide valve
254:Locomotives
130:superheater
1039:Categories
968:Steam drum
963:Steam dome
881:Three-drum
841:Field-tube
808:Transverse
793:Locomotive
750:Lancashire
537:2008-12-28
495:References
412:(LSWR) at
343:lubricated
170:economizer
148:, in some
76:newspapers
735:Egg-ended
596:650412984
474:switchers
445:H15 class
341:properly
319:air pumps
106:June 2016
1014:Injector
953:Smokebox
886:Vertical
871:Stirling
861:Sentinel
856:Monotube
813:Vertical
745:Haystack
387:I3 class
285:smokebox
271:clarity.
224:condense
1045:Boilers
933:Firebox
783:Haycock
773:Cochran
730:Cornish
711:Boilers
420:of the
408:of the
396:of the
195:turbine
90:scholar
891:Yarrow
866:Spiral
851:LaMont
803:Scotch
798:Pistol
788:Launch
669:
594:
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558:
416:, and
315:dynamo
216:boiler
92:
85:
78:
71:
63:
846:Flash
755:Wagon
740:Flued
404:, by
210:In a
160:Types
97:JSTOR
83:books
958:Stay
667:ISBN
592:OCLC
582:ISBN
578:RCTS
556:ISBN
317:and
144:for
69:news
725:Box
400:at
333:or
275:In
52:by
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629:^
613:^
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435:.
128:A
703:e
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689:v
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113:(
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104:(
94:·
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