![Mersey Railway No](https://upload.wikimedia.org/wikipedia/commons/6/6c/Mersey_Railway_No._5_Cecil_Raikes.jpg)
A condensing steam locomotive is a type of locomotive designed to recover exhaust steam, either in order to improve range between taking on boiler water, or to reduce emission of steam inside enclosed spaces. The apparatus takes the exhaust steam that would normally be used to produce a draft for the firebox, and routes it through a
heat exchanger
A heat exchanger is a system used to transfer heat between a source and a working fluid. Heat exchangers are used in both cooling and heating processes. The fluids may be separated by a solid wall to prevent mixing or they may be in direct conta ...
, into the boiler water tanks. Installations vary depending on the purpose, design and the type of locomotive to which it is fitted. It differs from the usual
closed cycle condensing steam engine, in that the function of the condenser is primarily either to recover water, or to avoid excessive emissions to the atmosphere, rather than maintaining a
vacuum
A vacuum is a space devoid of matter. The word is derived from the Latin adjective ''vacuus'' for "vacant" or " void". An approximation to such vacuum is a region with a gaseous pressure much less than atmospheric pressure. Physicists often di ...
to improve both
efficiency and
power
Power most often refers to:
* Power (physics), meaning "rate of doing work"
** Engine power, the power put out by an engine
** Electric power
* Power (social and political), the ability to influence people or events
** Abusive power
Power may a ...
.
Thermodynamics
Unlike the
surface condenser
A surface condenser is a water-cooled shell and tube heat exchanger installed to condense exhaust steam from a steam turbine in thermal power stations. These condensers are heat exchangers which convert steam from its gaseous to its liquid stat ...
often used on a
steam turbine or
marine steam engine
A marine steam engine is a steam engine that is used to power a ship or boat. This article deals mainly with marine steam engines of the reciprocating type, which were in use from the inception of the steamboat in the early 19th century to their ...
, the condensing apparatus on a steam locomotive does not normally increase the power output, rather it decreases due to a reduction of airflow to the firebox that heats the steam boiler. In fact it may reduce it considerably. Condensing the steam from a high volume gas to a low volume liquid causes a significant pressure drop at the exhaust, which usually would add additional power in most steam engines. Whilst more power is potentially available by expanding down to a vacuum, the power output is actually greatly reduced compared to a conventional steam locomotive on account of the lower air flow through the firebox, as there is now no waste steam to
eject into the firebox exhaust in order to pull more air into the firebox air intake. In order to produce similar power, air to the firebox must be provided by a steam driven or mechanically driven fan. This often cancels out any improvement in efficiency.
The temperature of the exhaust steam is greater than typical stationary or ship-based steam plant of similar power due to having fewer waste recovery stages, as ships often have an additional low pressure stage or even a low speed turbine. Waste heat on modern steam plants is often recovered using heat exchangers. However, condensing locomotives do not have this benefit due to the waste heat being expelled to the surrounding air and not being recovered, and therefore none of the
energy
In physics, energy (from Ancient Greek: ἐνέργεια, ''enérgeia'', “activity”) is the quantitative property that is transferred to a body or to a physical system, recognizable in the performance of work and in the form of hea ...
in the waste steam is recovered to do mechanical work. In many conditions the temperature gradient is often much worse due to using air instead of having an abundant source of cooling water, which is usually the case with naval or stationary steam power plants. The
Anderson condensing system
Advanced steam technology (sometimes known as modern steam) reflects an approach to the technical development of the steam engine intended for a wider variety of applications than has recently been the case. Particular attention has been given to ...
significantly reduces these losses by only partially cooling the waste steam before compressing it into condensate, then pumping the high temperature condensate back into the boiler in order to recover the unused waste heat. This greatly reduces energy waste.
Because of the relatively high temperature in a locomotive condenser and the rejection of the heat to the air, the potential improvement in
thermal efficiency
In thermodynamics, the thermal efficiency (\eta_) is a dimensionless performance measure of a device that uses thermal energy, such as an internal combustion engine, steam turbine, steam engine, boiler, furnace, refrigerator, ACs etc.
For a ...
expected from including the condenser in the cycle is not usually realised within the space constraints of a typical locomotive. Indeed, losses due to viscous
friction
Friction is the force resisting the relative motion of solid surfaces, fluid layers, and material elements sliding against each other. There are several types of friction:
*Dry friction is a force that opposes the relative lateral motion of ...
in the condenser piping, and having to pump the condensate back into the boiler is likely to reduce the power output over what was achievable from simply venting to atmosphere.
These restrictions do not apply to marine or stationary steam engines due to not having size or weight restrictions. Ships often had massive waste steam recovery systems, such as the 400 ton waste steam turbine used to recover very low 6psi waste steam on the Titanic and its sister ships. This is several times the weight of an entire locomotive, and so is clearly not feasible as a form of waste steam recovery for locomotives.
Exhaust draught
A drawback of condensing the exhaust steam is that it is no longer available to draw the fire, by use of the
blastpipe The blastpipe is part of the exhaust system of a steam locomotive that discharges exhaust steam from the cylinders into the smokebox beneath the chimney in order to increase the draught through the fire.
History
The primacy of discovery of th ...
. The draught must thus be generated instead by a steam-driven fan. Where possible, this has been arranged to use exhaust steam, although in some cases live steam was required, with extra steam and thus fuel consumption.
Types of condenser
Steam locomotive condensers may be water-cooled or air-cooled.
Water tank condenser
Here, the exhaust steam is blown into cold water in the locomotive's water tanks. A non-return system must be fitted, to prevent water from the tanks being drawn into the cylinders when the steam is shut off. This system was mainly used for locomotives working in tunnels.
Air condenser
Here, the exhaust steam is blown into an air-cooled radiator, similar to that used for the cooling system of an
internal combustion engine
An internal combustion engine (ICE or IC engine) is a heat engine in which the combustion of a fuel occurs with an oxidizer (usually air) in a combustion chamber that is an integral part of the working fluid flow circuit. In an internal c ...
. This system was used on small tram engines (where the condenser was mounted on the roof) and on large tender engines (where the condenser was mounted in the tender).
Anderson system
The
Anderson condensing system
Advanced steam technology (sometimes known as modern steam) reflects an approach to the technical development of the steam engine intended for a wider variety of applications than has recently been the case. Particular attention has been given to ...
uses an air-cooled condenser but the steam is only partially condensed to form an
aerosol of water droplets in steam. This aerosol is then liquified by pressure, using a specially-designed boiler feed pump. A fuel saving of nearly 30% (compared with exhausting to the atmosphere) was claimed for the Anderson system but this seems paradoxical. One would expect a higher fuel consumption because of the power required to compress the aerosol.
The reason this is possible is due to
Carnot's theorem, which states that pumping heat requires less energy than producing the heat itself.
A similar effect known as
Vapor-compression desalination
Vapor-compression desalination (VC) refers to a distillation process where the evaporation of sea or saline water is obtained by the application of heat delivered by compressed vapor.
Overview
Since compression of the vapor increases both the p ...
was later used for
desalination of water. Instead of returning the condensate water to the boiler, the hot compressed condensate is passed through a heat exchanger to return heat to the boiler, then released as clean drinking water. It is one of the most efficient processes used to desalinate water.
Purpose
There are two usual reasons for fitting condensing equipment - reducing exhaust
emissions and increasing range.
Reduced exhaust emissions
Underground railways
![Metropolitan Railway Steam Locomotive, London Transport Museum](https://upload.wikimedia.org/wikipedia/commons/9/94/Metropolitan_Railway_Steam_Locomotive%2C_London_Transport_Museum.jpg)
Originally developed for the
Metropolitan Railway to allow their locomotives to work the tunnels of the
London Underground
The London Underground (also known simply as the Underground or by its nickname the Tube) is a rapid transit system serving Greater London and some parts of the adjacent counties of Buckinghamshire, Essex and Hertfordshire in England.
The ...
. This system was devised by
Daniel Gooch
Sir Daniel Gooch, 1st Baronet (24 August 1816 – 15 October 1889) was an English railway locomotive and transatlantic cable engineer. He was the first Locomotive Superintendent, Superintendent of Locomotive Engines on the Great Western Rai ...
and developed by
Beyer, Peacock & Company. Steam is diverted from the exhaust steam pipes into the water tanks via condensing pipes within the same tanks.
The water in the tanks could quickly heat up near
boiling point, reducing the condensing effect on the exhaust steam. It was not unknown for the tanks to be emptied and refilled with cold water on a regular basis. Ordinary
injector
An injector is a system of ducting and nozzles used to direct the flow of a high-pressure fluid in such a way that a lower pressure fluid is entrained in the jet and carried through a duct to a region of higher pressure. It is a fluid-dynamic ...
s will not work with hot water
(until hot-water injectors were developed) so condensing locomotives were usually fitted with
axle-driven
boiler feedwater pump
A boiler feedwater pump is a specific type of pump used to pump feedwater into a steam boiler. The water may be freshly supplied or returning condensate produced as a result of the condensation of the steam produced by the boiler. These pumps are ...
s. When not working in tunnels, the steam was directed to the
blast pipe The blastpipe is part of the exhaust system of a steam locomotive that discharges exhaust steam from the cylinders into the smokebox beneath the chimney in order to increase the draught through the fire.
History
The primacy of discovery of ...
and up the chimney in the usual way.
Roadside tramways
In Britain, locomotives working on roadside
steam tramways were required by law to have condensers. Water tank condensers (as above) were sometimes used but air-condensers were more common. A steam
tram engine
A tram engine is a steam locomotive specially built, or modified, to run on a street, or roadside, tramway track.
Legal requirements
In the steam locomotive era, tram engines had to comply with certain legal requirements, although these varie ...
usually had a full-length roof and this was surmounted by a nest of air-cooled copper tubes in which the exhaust steam was condensed.
Kitson & Company
Kitson and Company was a locomotive manufacturer based in Hunslet, Leeds, West Yorkshire, England.
Early history
The company was started in 1835 by James Kitson at the Airedale Foundry, off Pearson Street, Hunslet, with Charles Todd as a par ...
made many engines of this type. The system was satisfactory for tram engines (which were very low-powered) but would not have worked for larger railway locomotives.
Increased range
Generally this was a more sophisticated installation that used forced air cooling to condense the exhaust steam. The system was intended to reduce the problems of getting enough water to steam locomotives running through desert and very arid areas, e.g. South Africa. (See below)
Locomotives fitted with a condensing apparatus
With water tank condensers
*
Caledonian Railway 0-4-4T
*
Central London Railway tube-gauge 0-6-0T
*
Great Eastern Railway class G69 2-4-2T
*
Great Eastern Railway class L77 0-6-2
Under the Whyte notation for the classification of steam locomotives, represents the wheel arrangement of no leading wheels, six powered and coupled driving wheels on three axles and two trailing wheels on one axle. The type is sometimes kno ...
T
*
Great Eastern Railway class M15 2-4-2T
*
Great Northern Railway class J13 0-6-0T
*
Great Northern Railway class L1 0-8-2
Under the Whyte notation for the classification of steam locomotives, 0-8-2 represents the wheel arrangement of no leading wheels, eight powered and coupled driving wheels on four axles, and two trailing wheels on one axle (usually in a trailing ...
T
*
Great Northern Railway (later LNER) class N2 0-6-2T
*
Great Western Railway Metropolitan Class 2-4-0
Under the Whyte notation for the classification of steam locomotives, represents the wheel arrangement of two leading wheels on one axle, four powered and coupled driving wheels on two axles and no trailing wheels.
The notation 2-4-0T indi ...
T
*
Great Western Railway 633 class 0-6-0T
*
Great Western Railway 9700 class 0-6-0PT (a variation on the
5700 Class)
*
London, Chatham and Dover Railway R class 0-4-4T
Under the Whyte notation for the classification of steam locomotives, 0-4-4 represents the wheel arrangement of no leading wheels, four powered and coupled driving wheels on two axles, and four trailing wheels on two axles. This type was only used ...
*
LMS Fowler 2-6-2T
*
Mersey Railway
The Mersey Railway was the first part of the passenger railway connecting the communities of Liverpool, Birkenhead, and now the rest of the Wirral Peninsula in England, which lie on opposite banks of the River Mersey, via the Mersey Railway Tun ...
0-6-4T No.5 ''Cecil Raikes'' (preserved at the
Museum of Liverpool
The Museum of Liverpool in Liverpool, England, tells the story of Liverpool and its people, and reflects the city's global significance. It opened 2011 as newest addition to the National Museums Liverpool group replacing the former Museum of ...
)
*
Metropolitan Railway A Class
The Metropolitan Railway A Class and B Class were condensing steam locomotives built for the Metropolitan Railway by Beyer Peacock, first used in 1864. A total of 40 A Class and 26 of the slightly different B Class were delivered by 1885. Used ...
4-4-0T
*
Metropolitan Railway B Class 4-4-0T
*
Metropolitan Railway C Class 0-4-4T
*
Metropolitan Railway D Class
The Metropolitan Railway D Class was a group of six locomotives built for the Metropolitan Railway in 1894-1895 by Sharp, Stewart and Company.
Overview
Two locomotives were used on the Verney Junction-Aylesbury section. The other four ran betw ...
2-4-0T
*
Metropolitan Railway E Class
The Metropolitan Railway E Class is a class of 0-4-4T steam locomotives. A total of seven locomotives were built between 1896 and 1901 for the Metropolitan Railway: three by the railway at their Neasden Works and four by Hawthorn Leslie and Comp ...
0-4-4T
*
Metropolitan District Railway 4-4-0T
With tender air condensers
*
Deutsche Reichsbahn class 52. Around 200 of these were built with condensing tenders, to reduce the visible exhaust plume and so avoid air attacks on the
Eastern Front of
World War II
World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the vast majority of the world's countries—including all of the great powers—forming two opposing ...
.
* Russian
SO class. From 1936 some of these were built with
P11 condensing tenders for use across deserts in
Turkestan
Turkestan, also spelled Turkistan ( fa, ترکستان, Torkestân, lit=Land of the Turks), is a historical region in Central Asia corresponding to the regions of Transoxiana and Xinjiang.
Overview
Known as Turan to the Persians, western Turk ...
.
*
South African Class 20 2-10-2
The South African Railways Class 20 2-10-2 of 1935 was a steam locomotive.
In 1935, the South African Railways placed one Class 20 steam locomotive with a Santa Fe type wheel arrangement in service, designed and built at its Pretoria Mechanica ...
*
South African Class 25 4-8-4
*
South Manchuria Railway Mikaku class 2-8-2
See also
*
Jet condenser
*
Kirchweger condenser
*
Surface condenser
A surface condenser is a water-cooled shell and tube heat exchanger installed to condense exhaust steam from a steam turbine in thermal power stations. These condensers are heat exchangers which convert steam from its gaseous to its liquid stat ...
References
External links
{{Steam engine configurations
Steam locomotive technologies