Although the Elesco’s were the most appealing in my opinion, what feedwater heater (and valve gear) was the most efficient and why? If a new “classic” steam locomotive were to be built today which would it utilize?
I believe Coffin was the first design followed by Elesco and finally the Worthington was the latest and probably most effective and modern design.
Elesco was the least efficient but easiest to identify because of the famous cylinder bundle mounted just ahead of the locomotive stack.
Elesco was a “closed design” because it kept exhaust steam and boiler feed water separate from each other in order to prevent cylinder lubrication oil which was in the exhaust steam out of the boiler intake water.
The very successful Worthington was a “open design” because it mixed exhaust steam into the feed water. Worthington had developed a separator design to extract the oil.
Worthington is usually seen as a small tank or box just ahead of the locomotive smoke stack but is really a large tank sunk into the front end design of the locomotive smoke box.
Feed water heaters were not widely added to steam locomotives in the United States until the 1920’s. They were one of the truely modern locomotive appliances that increased the performance and efficiency of the engine.
Early 1920s designs almost overtook the locomotive with all of the external plumbing and large clumbsy pumps they used. For example the Elesco “closed design” heater tube bundle was a large beadle brow mounted on the boiler top. The Coffin design was sometimes mounted externally and appeared as a large “horse shoe” tank mounted over the smoke box door.
In the 1920’s you will notice most all of the plumbing necessary to effect the feed water systems was hung along the outside of the boiler giving a sometimes ugly mess appearance to the locomotive with a huge pump often carried on the left side of the engine.
As the 1930’s progressed the systems were perfected and the piping and pumps became almost invisible. New York Central Hudsom 4-6-4 sunk the Elesco “closed design” bundle down into
The idea that feedwater is admitted ‘cold’ might have been true in the mid-Nineteenth Century, in the days of rod-driven pumps, but a moment’s reflection will show that any locomotive using an injector will have hot feedwater. The concern is that, because of the way an injector operates, it cannot use feedwater that is hot enough to ‘flash’ to steam during injection. A FWH system with a hot-water pump does not have this limitation.
Note that a delivered-water temperature in the range quoted (200-250 deg.F) is still well shy of the actual equilibrium temperature of water in a typical large Super-Power locomotive, particularly one that uses “modern” high pressure of 300 psi or higher. Part of the importance of FWH on such locomotives is to reduce thermal cycling of parts of the boiler structure. Do you not mean the rise in temperature through the heater, starting with water at whatever temperature the cold-water pump delivers?
During the ‘age of steam’ the use of FWH was driven by economics – the substantial first cost and mintenance costs of the system being balanced against the financial results of the benefits. It is interesting to note that one of the most sophisticated modern locomotives, C&O 614, had her (admittedly poor) FWH system removed early in her life, and never replaced even during the 614T testing. On a ‘preserved’ locomotive, the advantages of good FWH may take on more importance, more for the preservation of boiler integrity than for any supposed improvement in fuel economy (which saving is a minuscule part of the overall cost of running big steam) or nominal water rate.
Might be a good idea to discuss heat recovery in the Rankine cycle, an i
Dr. D,
This is maybe one of the biggest myths ever and needs to be busted.
For example, the temperature of unsaturated steam (which the injector uses) at 300 psi is 421.7 degrees F (water tempurature varies, plus or minus, according to the pressure). For all intents and purposes, all of this heat is transfered to the feedwater going into the boiler. So, there is absolutely no “almost freezing” water going into the boiler. Somewhere in the 200+ degree range may be more like it.
Hot water supplied from the feedwater heater is in about the same temperature range, varying according to how hard the locomotive is being worked.
The idea that using the injector for putting cold* water into the boiler and knocking down the boiler pressure is pure myth also. The reason the boiler pressure lowers is because boiler pressure is being used to inject the water into the boiler.
- “Cold” is a relative term. As we have just seen, the feedwater isn’t cold at all. The water in the tender is “Cold”. The feedwater going into the boiler, whether it be by use of the injector or the feedwater heater is very hot compared to the tender water, yet, colder (200+ degrees) than the water at boiler pressure (420 degrees).
Use the following links (wait for them to load) to learn about:
Injectors: http://www.icsarchive.org/icsarchive-org/bb/ics_bb_508d_section_5236_locomotive_injectors.pdf
Feedwater Heaters: http://www.icsarchive.org/icsarchive-org/bb/ics_bb_508d_section_2517_locomotive_feedwater_heating_equipments.pdf
Ralph Johnson design engineer for Baldwin Locomotive Works offers a differing opinion concerning the feed water heater designs,
"The preheating of boiler feed water by means of waste exhaust steam is a highly important economy without which no heavy-duty locomotive can be considered efficient. The reasons, summarized briefly are:
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On any boiler it increases the maximum evaporative capacity, no matter how efficient the boiler may be in itself.
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For equivalent evaporative capacities it decreases the weight of the boiler.
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The effective tender capacity is increased.
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Boiler maintenance is decreased because a percentage of the feed water is returned in the form of condensed steam or distilled water.
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Produces an increase in the general over-all efficiency of the locomotive.
Feed water heating reduces the amount of heat which must be supplied by the fuel for the generation of steam, and for a given locomotive there will be either a decrease in coal consumption for a given evaporation, or the total evaporation of the boiler will be increased if the same quantity of fuel is burned. In either case a pound of fuel will evaporate a greater amount of water than would be the case if cold feed water were used. Also, as exhaust steam in the form of condensate is returned to either the boiler or the tender tank, it follows that a smaller amount of cold water will be required and in this way there will be a reduction of cold feed water used per horsepower developed. The cylinder performance, however, is not affected by feed water heating except that there is some reduction in back pressure, as less steam is passing through the nozzle when the heater is in use…
Theoretically the feed water heater can add up to 18 per cent to the maximum evaporative capacity of the boiler, depending upon the temperature of the water in the tender and the
Differing from what?
Big Jim,
Ralph Johnson pointed out a number of functions of the feed water system not discussed. From its function as a condenser to the overall evaporative contribution and stabilzation of the boiler. Many engines rely on it for effective feed water in place of the lifting injector and as a safeguard to boiler explosion. The consideration of removal of the system as surpurflious is highly misleading to the overall safety and function of the operational steam locomotive.
The Gettysburg PA tourist line boiler explosion that caused the government to completely redesign the FRA rules for operating steam locomotives in the 21 Century was a result of the lifting injector failing and the feed water system not fuctioning in boiler water supply. It was also caused by the ignorance of the crew and non functioning water glass.
To leave the impression that excursion engines could do away with the sytem misunderstands their function and contribution to locomotive operation.
When Ross Rowland made the statement about “We threw out the FWH because in was un-necessary - didn’t work anyway!” this sounds cavalier and about equal to “CO 614 whistling past the graveyardd!”
“Ross Rowland and CO 614 being a play toy of a millionare aside, that engine needed its feed water system!”
Doc
They have installed a feedwater heater on Sou. 4501.
The thing about the steam locomotive is having a dirt-simple machine using a dirt-cheap fuel. Once your start tinkering with that relationship, things get . . . complicated.
I am sitting here with my copy of The Wonderful World of Energy by Lancelot Hogben, published by Doubleday. There is an illustration of Joule spending his honeymoon measuring the temperature difference in a waterfall, with his patient newlywed bride Mrs. Joule taking a reading from the top and Mr. Joule taking a reading at the bottom. They could find no difference.
The lesson is that when scientists such as Joule and his patient wife and others started studying the underpinnings of thermodynamics, notably the relationship between mechanical action (work) and heat, it takes an enormous amount of work to generate measurable amounts of heat. Conversely, if you generate a large amount of heat by burning coal in the steam engine, and even if you convert only a tiny fraction of that heat to work, you get usable and economically beneficial amounts of work in the form that can propel the train.
That was an essential feature of the Industrial Revolution. Even if you used heat inefficiently to generate work, you could do many useful things and work on improving efficiency step-by-step over time.
That was also another feature of Industrial Progress. You started out with very inefficient conversion of heat into work and made various improvements, step-by-step and over time to get the much more efficient engines we have today.
If the keep-it-simple-(and)-stupid (KISS) principle was an iron law with the iron horse, steam locomotives would have never gotten superheaters. The diesel-electric locomotive that superceded steam entirely, on the other hand, is a pretty complicated thing that was also rather expensive in relative terms back-in-the day.
There is a tendency to view the steam locomotive as the dirt-simple design that engineers kept adding complications to (su
And, a mechanical stoker.
And, as I understand it, roller bearings on the lead and trailing trucks. Why ever not?
Paul Milenkovick,
Nice piece on the efficiency of external combustion! The Red Devil class of South Africa left quite a heritage we could all become more familiar with! As I said, nice piece.
Doc
The Worthington open style feed water heater had another advantage. By heating the water to near the atmospheric boiling point in a vented vessel, most of the air/oxygen in the feed water was driven off before it reached the boiler. Oxygen in feed water is a bad thing since it corrodes away the boiler steel (oxygen plus steel in the presence of water = rust). The Elesco and Coffin closed feed water heaters were not able to remove oxygen nor did injectors. Chemical treatment of feed water could also remove oxygen, but chemical treatment of boiler feed water by railroads seems to have been a pretty ‘iffy’ subject.
Here is a link to an externally installed Coffin-style Feedwater heater on a Lima-built 2-8-4 Berkshire of the B&M. see @ http://abpr.railfan.net/abprphoto.cgi?//november98/11-01-98/bxm4009.jpg
These engines were problems for the B&M and were traded to western US RR’s to help with the WWII war effort[note: 10 to SP, and 7 to AT& SF]. see @ http://www.steamlocomotive.com/berkshire/?page=bm
The Coffin-style was favored on the Frisco but was generally built inside the smoke boxes. See link @ http://thelibrary.org/lochist/frisco/friscoline/images/photos/p01389.jpg
The Worthington Feed water Heater was usually mounted in a transverse fashion on the top of the Locomotives smoke box as showin on this T&P ‘Texas’ type #546. See @ http://www.llarson.com/steam/schenzinger/images/NA129.jpg
this link as well, might be of interest on this Thread @ http://www.steamlocomotive.com/appliances/feedwaterheaters.php
Once again, another site that continues the “Cold” water myth.
Sam,
Your mixing up the Elesco and the Worthington.
Elesco is a closed system that resembles the bundle on the top front of the boiler. This “beetle brow” was quite distinctive. Early designs such as this Texas and Pacific 600 have all the plumbing outside the locomotive for that wonderful “clutered look.” NYC early freight Mohawks were also famous for the Elesco “beetle brow” and they matched it with similar outside plumbing. ATSF was also a user of the “beetle brow” Elesco such as the famous 2-10-4 Madame Queen.
Later NYC Hudsons also had this Elesco “closed design” but you couldn’t tell it was Elesco because the “beetle brow” was gone, it was sunk down into the smoke box so only the ends of the bundle protruced out of the boiler jacket. Thus they did away with the famous “beetle brow” which was so distinctive and which some people thought was very attractive! The plumbing was also mostly hidden on these late feed water heater designs making the engines less rugged looking and quite slick for American steam engines.
Worthington heaters were a square box hardly visible in front of the engine stack. Worthington were the last and best type feed water heaters and were of the “open design” - which mixed the pre heat steam with the incoming boiler water. These are pretty common today on most surviving steam locomotives today. ATSF 3463, UP 844 are examples.
Doc
Didn’t some roads have locomotives with the Elesco “bundle” on the pilot deck? Seems to me I’ve seen that but can’t recall which road it was.
Canadian National and Grand Trunk Western used bundles on the pilot but they were “air reservoirs” tanks used for storage of compressed air. The air was used in the application of the train air brakes and engine air brakes.
A feed water heater must be located so that it can work - what does it work on but exhaust steam from the cylinders as it is on the way to the stack. It is diverted to a chamber or bundle where cold tender water may be heated. There would be no purpose for placing this on the engine pilot deck.
The ATSF 3460 Hudson 4-6-4 engines used a feed water pump located on the pilot deck which fed water into the Worthington Feed Water Heater located in the smoke box just ahead of the smoke stack.
Every appliance on a railroad steam locomotive had a useful designed place and purpose. The railroad steam engine was unlike other stationary or marine steam engines - it was compact - designed for quick generation of great power - and repairable - and would travel over land propelling itself. Patterns of locomotive design developed and they were never changed. Even the Chinese were copying the basic locomotive design developed in Europe and in the United States - decades after.
In fact the BASIC LOCOMOTIVE DESIGN OF ROBERT STEPHENSON 1829 who created the first workable steam railroad locomotive was not changed to THIS DAY!
What was this design - a horizontal multi fire tube boiler fed with draft induced by the cylinder exhaust blast pipe. Separate firebox surounded by water feeding into the multi tube boiler. The cylinders directly “double acting” upon drive wheels.
These concepts were never changed from the first English locomotive design 1829 to the NYC HUDSON and PENNSY T-1 of 1940.
Doc
My understanding of this from “Red Devil” is that a feedwater heater diverts exhaust steam from when it comes out of the cylinders to provide heat for the feedwater. Generally, this steam is exhaust out the stack, but being run through the restriction of the feedwater heater, it no longer contributes to the exhaust blast that furnishes the draft. That is why if you divert a lot of exhaust steam (feedwater heater, Porta and others had proposed combustion air preheaters as well), you need a really efficient blast nozzle. This is needed to get enough draft with the remaining “blast” steam.
Also, a feedwater heater condenses some of the steam fed to it, and this water recovery reduces the “water rate” of the locomotive by partially condensing the exhaust steam.
The other thing Wardale mentions is that the steam at exhaust valve opening still has considerable pressure, a pressure that can be much higher than the back pressure during the duration of the exhaust stroke. A similar “blow down” occurs in internal combustion exhaust valve opening. Using a check valve, the feedwater heater can receive exhaust steam under pressure that is elevated above the atmospheric boiling point of water. This mean that in theory, a feedwater heater could preheat the incoming water to above 212 F of the atmospheric boiling point.
The exhaust steam is under this blast of “blowdown” pressure under long cutoffs and full throttle (“hard” working of the engine). But Wardale also suggests reaching high levels of feedwater temperature may require a two-stage design that no one used. It certainly requires a “closed shell” design because a feedwater heater of the open type operating at atmospheric pressure is limited to 212 F.
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