Dr D Wizlish, Glad to see you chime in on this discussion, but when did throwing out a bunch of technical names and vague comments constitute a legitimate retort?
Wizlish,
Glad to see you chime in on this discussion, but when did throwing out a bunch of technical names and vague comments constitute a legitimate retort?
Ye gods, just the kind of discussion I love, and I have been missing it completely! Let me take up some of the points with a bit more detail. I keep thinking that because I've seen technical detail, it's self-evident to others with serious interest and knowledge of steam practice... that's a dumb assumption. As my great-grandmother used to say, 'ignorance is not stupidity'. (Except when it is ignorance as shown by me in assuming everyone knows the esoteric stuff!)
... I cannot come to believe that a modern engineering and computer design "poppet valve" concept could not overcome all of these limitations cost effectively.
Much of the effective limitation was solved in between the PRR efforts in '47-'48 to fix the T1 problems (many of these, like better centrifugal casting of the valves, were never implemented) and the system on ATSF 3752 that is described in Vernon Smith's One Man's Locomotives. The 'catch' is that even the simplified used in Franklin type D (which uses a kind of wire-drawing effect to produce the effect of cutoff as speed increases) has complicated gears and shafts that require close alignment and careful maintenance. With the advent of comparatively cheap CAD/CAM, many of the objections to designing and fabricating the 'nightmare boxes' are reduced. But there is still much more involved in providing all those valves and seats and springs and cams when the alternative is a (comparatively) simple articulated, multiple-ring long-lap long-travel piston valve (or Willoteaux valve if you need the equivalent of multiple ports opening in parallel)/ driven by a simple pin-jointed linkage like Baker gear.
"Sleeve valve" as used in early automobiles and in Ricardo's work
These have almost as grim a history as rotaries in steam-locomotive practice. About the closest I think they came to workability was the setup used in Bulleid's Leader, where a Meehanite sleeve with a great plurality of ports was used, between the piston and the cylinder wall. This design had probably the lowest possible dead space of any workable arrangement, and (naturally!) very good theoretical high-speed steam admission. But the design showed also a remarkable capability to start leaking steam if even one of the very substantial number of sealing rings cracked or wore -- and even a cursory examination of the required lubrication arrangements would convince you that 'cost-effective' was an adjective to describe the setup. (I am tempted to point out that when Bulleid attempted a Leader-style arrangement later, in Ireland, he used more-or-less conventional piston valves.)
"Rotary valve" as used in some internal combustion motor designs such as CSRV.
And they work, if anything, even worse than they did in IC engines. Two words for you: Paget locomotive. Differential expansion vs. required tight sealing makes for an operational disaster in typical railroad service.
A possible way around this is to adapt an idea from a British design called an 'asynchronous compound' -- have the rotary valve always work with a slight clearance, and use the 'slip' together with the exhaust steam in a compound arrangement of some type. But the simplicity you gain from the absence of sealing -- or inadvertent interference fits -- will be bought at a comparatively high price... in a number of respects.
I won't go into how you keep a rotary valve exposed to highly superheated steam lubricated, while keeping lubricant out of the exhaust (or using enough antifoam in the water treatment!) so you can use an open FWH.
"Reed valve" as in two stroke interal combustion and modern compressors.
I'll bite -- just how would you propose using these on a high-pressure steam locomotive?
I for one cannot think of any other common valve designs applicable to power producing machinery...
Well, you left out a biggie -- the 'bash valve'. Arguably the simplest valvetrain you can have -- a projection on the piston crown lifts a ball off its seat against spring restoring force. I'd agree that poppets are better than these for large railroad locomotives, but if you are converting a locomotive diesel prime mover to run on steam (as in Perry Shoemaker's approach) the bash valve remains an interesting potential approach.
... Possibly the Wardale articulated design with Baker action was a workable compromise for commonly accepted maintaince schedules Wardale was confronted in maintaining Red Devil.
Wardale himself has been forthright in saying that he considers proper piston valves to be a better solution in practice, for a working locomotive, than poppets. Note that the advantages of the Franklin System only prevail at high speed AND high delivered power -- examine the performance of, say, the T1 with Franklin OC valve gear vs. the T1a with piston valves and Walschaerts gear.
The multi roll bearings and diesel piston rings on piston valves is novel considering the problem with "carbon sticking piston valves" that high demand situations created (such as when Pennsy borrowed a N&W 600 for tests and stuck the valves).
Note that 'Multirol' is a trade name for a particular make of needle bearing. And they are diesel-style rings, not repurposed actual diesel-engine piston rings -- the metallurgy and characteristics are usually different.
The carbon sticking the rings is, of course, derived from superheated steam coking the lube oil needed to keep rings sliding. There are approaches that ought to reduce this -- the Spilling company, for example, makes engines that can use upward of 1000-degree steam without using oil lubricant. A useful thing here is to look up the old enginion AG "zero emission engine" -- which I still find an intriguing design -- and examine how its tribology was arranged.
"Trofimov valves as improved by Meiningen, or Wagner bypass valves!" I cannot believe you would introduce a subject title like this without some explanation of them. They represent quite an insight into new thoughts on piston valve design.
Well, actually not all that new. The Trofimov valve is a functional improvement on an older design (the Nicolai valve, which had an interesting history) -- it provides automatic bypass action when the locomotive is drifting. There are, or were, operating instructions for the system on the Web -- look for references to locomotive 3025, which had them. Perhaps this link to a .pdf will still work.
Here is a picture of a Wagner bypass valve (as fitted to a large ATSF locomotive expected to run at high speed):
A point that was raised in discussion is that Trofimov valves can be fitted to most any locomotive with piston valves -- the Wagner bypass requires its own housing in the cylinder casting.
I also cannot believe you would bring up "compression control" and its importance without some discussion because it is the subject of choice to continue this thread. Walschearts design and Baker designs primarily failed because they kept back the tremendous efficiencies that could have been realized in reciprocating steam locomotives when operated at "limited cut off."
The compression control is really more about reducing momentum effects at high speed than it is about suppoosedly "tremendous efficiencies" to be gained by limited cutoff. I would refer you to the people responsible for the Duke of Gloucester, a locomotive that can reliably operate at over 95% cutoff without mechanical damage -- there are practical limits to how much cutoff can be used while still making the required power to propel the engine at speed, and those are nowhere near what the valve gear can reliably produce.
I don't know if the thermodynamic and water-rate improvements of Jay Carter-style compression control (look it up on the SACA 'phorum' if you have to) would be valuable enough on large locomotives to justify their use over the simpler Okadee valves that just vent excessive compression.
Wardale and his support by South African Railway hardly compares to what Pennsylvania Railroad pursued with the T-1 duplex drive development or that New York Central under Paul Kiefer was attempting in similar situation to Wardale with the NYC 6000 series Niagaras. Time was indeed running out.
With the cost of diesel fuel in the present age some doubt remains that the diesel electric locomotive could have displaced reciprocating steam locomotive if it had been allowed to continually develop to its full potential.
Even with diesel fuel at ten times the cost it was in the Forties, it is highly likely that some form of diesel traction would have become highly adopted. Remember that very few people (outside GM-EMD, of course!) were expecting steam to disappear anywhere near as quickly as it did in North America. The various unavoidable inefficiencies of big steam -- starting, perhaps, with all the problems and issues related to water, which the diesel avoided entirely, and finishing up with all the manpower reductions that dieselization facilitated -- were one of the major factors, as was the 'critical mass in reverse' when it became increasingly impractical for specialty manufacturers of essential steam-locomotive systems to stay in business. When superheater elements can't be built or rebuilt to order quickly and easily by experts, and arch brick is no longer made or delivered when needed, or you can't get parts to your fancy FWH pumps -- even a large theoretical saving in fuel gets eaten up pretty quickly.
And I'd expect the UMW to be increasing the cost of decent steam coal
And then there is the environmental pollution issue. Smoke was already a serious concern by the late '40s. Things like total-loss lubrication, ash dumping, ejection of fines in the exhaust, or continuous blowdown dribbling nice alkaline water all over the railhead would not have been tolerated if there had been a substantial number of working mainline steam locomotives left.
Dr DA 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.
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The Elesco, Coffin, and Worthington feed water heater systems consisted of water pump or pumps - one sometimes two - and the heat exchanger. The pump was often on the pilot deck but sometimes on the side of the locomotive - the early ones were huge. The all important heat exchanger - which was of the "open type" or "closed type" - was usually ahead of the stack. The "open type" mixed exhaust steam with the cold water feed into the boiler, the "closed type" did not mix but used a system of hot pipes to heat the cold boiler intake water.
Both of these systems were common to many late ATSF steam locomotives like ATSF Hudson 3463 in Topeka KS - Worthington "open system" with water pump on the pilot deck - and many other railroads.
An examination of ATSF 4-6-2 Pacific 3415 does indeed show what appears to be the Elesco bundle - "closed system" on the pilot deck. Can't say I have seen many in this location. Looks good though!
Doc
cefinkjr 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.
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.
Dr D It is held that the internal combustion engine thermal efficiency is on the order of 25-30%...
It is held that the internal combustion engine thermal efficiency is on the order of 25-30%...
Sure, if you are talking about a 1960's era gasoline engine. Many modern car engines are in the 30% - 35% range. Toyota has some engines that are up around 38%. Modern turbo-diesels are easily in the 40% - 45% range, while large marine diesels are 50% to 52% thermal efficient.
Dr DIt is held that the internal combustion engine thermal efficiency is on the order of 25-30%, and the external combustion reciprocating steam locomotive thermal efficiency on the order of 10-20%. These basic statistics are often given. Steam powerplants, however, have achieved thermal efficiency as high as 40-50%.
Doc, ya gotta remember that steam plants get their high efficiency in ways that cannot be packaged practically on locomotives. They rely on very steady and continuous operating conditions, they usually have lousy turndown ratio (and in many cases turndown actually leads to boiler and refractory damage as the combustion gas paths etc. change!), they do feedwater heating with multiple bleed stages on the turbine, they use radiant superheating and exhaust into a substantial vacuum with enormous plenum volume...
The Carnot cycle represents the absolute maximum efficiency that can be used by an engine that uses heat to expand a gas and push something to do work -- a piston, a turbine blade, etc. That neatly corresponds to the maximum work that can be done with, say, an internal combustion engine, which generates its combustion gas entirely within the cylinder. An external-combustion system, though, can follow the Rankine cycle, which looks at the most effective way of using the heat to produce a given amount of work practically -- can exhaust heat be used to preheat water, or air for combustion, or can steam at higher temperature preheat a cylinder to reduce wall temperature when steam at lower temperature is admitted for power, for example.
The thing is that many of the ways in which heat is most effectively transmitted from combustion to work involve expensive, or heavy, or bulky, or complicated systems, many of which do not take kindly to the environment encountered by working steam locomotives that have to earn their bottom-line keep. Perhaps nowhere is this illustrated better than condensing, but there are reasons why very effective and comparably simple devices like the Schmidt superheater, the Snyder combustion-air preheater, and the Cunningham circulator are things that ought to work well, things like the Franco-Crosti preheater/economizer and the popular kinds of American feedwater heater are more complex and involve more maintenance and tsurris (to the point they were removed as unworkable when their maintenance exceeded their economic benefit), and things like the Schmidt high-pressure system of NYC 4-8-4 and LMS Fury fame (and those D&H compounds) could never provide meaningful economic recovery of their costs.
Much of the promise of 'modern' steam involves the use of new materials to permit better retention of heat in the Rankine cycle, for example the use of aerogel lagging and jacketing or the use of thermal tiling or thermal-barrier coatings in part of the radiant gas path. An interesting point about the rebuilt European 2-10-0 8055 is that it is possible to maintain working steam pressure indefinitely by 'plugging in' an electric element of only about 35kW (and regulating it via a simple pressure transducer); this means that many of the losses and waste associated with "idling" steam power between runs can be reduced or eliminated.
Much of the attention, though, is not focused on improvements in the Rankine cycle so much as reducing the 'people machine' aspects that were so deadly to classic steam locomotive practice. That goes far beyond what NYC and N&W were able to do, and probably isn't of interest even to many of the people in this discussion, but one of the most important (to me) possibilities is the use of modern electronics and control theory to improve how the locomotive is 'driven' and fired. If you then (as I think you should) outsource and provide long-term procurement for cheap solid fuel -- cheap enough that your cost in delivered $/BTU or whatever is lower per ton-mile than that for diesels -- and if you can get your water-rate problems addressed, you're more likely to have something that can compete effectively in the markets where steam power has distinctive advantages over complicated diesel-electrics.
A couple things.
The 10-20% thermal efficiency of steam locomotives is perhaps the theoretical efficiency of what can appear on indicator diagrams with a 100% efficient boiler, mechanical transmission, perfect valves, no wall condensation loss in the cylinder, heat loss from uninsulated or poorly insulated firebox, boiler, steam pipes, valves, and cylinders. Wardale gives figures that year-in year-out efficiency can be as low as 3%.
The Brown studies suggesting that steam locomotive economics were more favorable than generally understood assigns a value that steam, on average, used 6 times the BTUs of Diesel locomotives. Wardale gives some figures suggesting that the fuel consumption of steam could be even higher than that.
My thinking is that using all of the Chapelon/Porta/Wardale/Girdlestone improvements to the Stephenson-type steam locomotive without going to "exotic stuff" like turbines, condensing, water-tube boilers could improve steam to 3 times the BTUs of Diesel, making steam competitive with coal-to-liquids and burning that in a Diesel instead of the coal directly in a steam locomotive.
I have read the white papers on the Coalition for Sustainable Rail, and here are my impressions. No disrespect intended, but I think this group is very much like the ACE 3000 project in motivation and intentions. What I mean by this is that they are railfans and steam enthusiasts (not that there is anything wrong with that!) who are carrying the environmental banner as a justification for doing work on "modern steam." They are simply not a group of environmentalists who got up one morning and though, "Gee, last bring back the steam locomotive to burn biomass!"
Furthermore, the Santa Fe Hudson is their version of the C&O Northern in the ACE 3000 project. They don't intend a 1940's Hudson to be the "final form" of their high-speed passenger solid-fuel burning passenger loco. Rather, it is a historical artifact that will serve as some initial phase or demonstration before going on to their 21st Century design.
They appear to take the preservation concerns seriously. I don't think they intend to "chop" their 4-6-4 and turn it into something looking like those ugly D&H high-pressure steam engines. Or to the extent that they plan to do a "Red Devil" treatment on it, they are earnest about promising to turning it back to "the way it was" to address worries that they are going to mutilate a historic steamer beyond recognition. Remember, the vibe I get is these dudes are steam nuts waving the enviro banner to get funding and a purpose rather than enviros doing something nuts with steam.
Remember, the 4-6-4 is meant as some kind of proof-of-concept to be followed by some kind of ACE 3000-like thing (maybe, hopefully not condensing and hence doable), although they may be holding off on their ACE 3000-like think until they get experience with their mods of the 4-6-4.
If GM "killed the electric car", what am I doing standing next to an EV-1, a half a block from the WSOR tracks?
8,300 posts! Impressive!
CSSHEGEWISCH this observaton is by no means a fact.
It is held that the internal combustion engine thermal efficiency is on the order of 25-30%, and the external combustion reciprocating steam locomotive thermal efficiency on the order of 10-20%. These basic statistics are often given. Steam powerplants, however, have achieved thermal efficiency as high as 40-50%.
Expense of crude oil per barrel has risen from $1 to 2 dollars per barrel in the 1940 and 1950's to todays high of $128 dollars per barrel. The steam locomotive was challenging the cost efficiency of diesel electric at the time diesel was adopted as America's prime mover in the 1950's. Today serious consideration is given to steam power as an alternative power source.
While more efficient in design the cost of diesel operation vs steam operation has been challenged by the attempt to produce steam locomotive ACE 3000, and by such enviornmental engineering groups as Coalition For Sustainable Rail to build an ATSF 3463 alternate steam prototype locomotive.
While the recent "shale oil boom" has lowered oil prices again the wide availability of cheep natural gas has caused diesel engine designers to think towards converting from diesel oil as a heat source to running on natural gas instead - supplied to the locomotive diesel engine by tank car bottle tenders as a viable option.
The consideration of steam power has merit for discussion on this site for historic purposes if not as as potential source for the engineering modern power.
Wislish has a great technical engineeing background he has been encouraging me in private e-mail to speak about the Rankine Cycle. I wish he would do so instead because with his advanced mathmatical background he really does a better job and has greater insight into this type of discussion.
Sometimes you have to provoke Wislish to get him to come out of his study - "to get big bear to come out of the cave!"
Doc.
The above post suggests that steam would have prevailed if the diesel-electric wasn't introduced until after additional improvements to steam were made. That would assume that the diesel-electric was a static design to which improvements could not be made. The fact remains that steam is dead or dying both on land and on sea.
Reading your text - I found we are in agreement on several points - first that when it comes to overall horsepower production the "poppet valve" arrangement is probably the top producer.
Second that the geared "poppet valve" designs from the 1930's and 40's were complex, expensive, and breakable - these designs however are over 75 years old. I cannot come to believe that a modern engineering and computer design "poppet valve" concept could not overcome all of these limitations cost effectively.
Lets speak of general engine valve designs -
- "Sleeve valve" as used in early automobiles and in Ricardo's work.
- "Rotary valve" as used in some internal combustion motor designs such as CSRV.
- "Piston valve" as used in most steam locomotive designs and potato guns.
- "Reed valve" as in two stroke interal combustion and modern compressors.
- "Poppet valve" from internal combustion and reciprocating steam.
I for one cannot think of any other common valve designs applicable to power producing machinery and "poppet valve" is the top choice for design efficiency in all modern engineering.
I do not think any designer would choose "piston valves" for reasons other than tradition and abject simplicity. Possibly the Wardale articulated design with Baker action was a workable compromise for commonly accepted maintaince schedules Wardale was confronted in maintaining Red Devil. The multi roll bearings and diesel piston rings on piston valves is novel considering the problem with "carbon sticking piston valves" that high demand situations created (such as when Pennsy borrowed a N&W 600 for tests and stuck the valves).
It is the nature of this site is to profer such discussion and you really need to share some of your fine understanding of these subjects. As it concerns where the reciprocating steam locomotive would have developed in the 1950's if given the chance.
Further, it is a given fact, that despite Wardale and his great success with Red Devil, the whole project "suffered from the outset by half hearted support on the side of South African Railroad managment, who by then had decided to replace all steam traction with electric and diesel-electric traction."
Obviously Wardale had to do what he could in a very shortening time frame. This was no situation to fully explore potential changes such as "poppet valve" vs. "piston valve" makeover of the Red Devil.
Wardale and this support by South African Railway hardly compares to what Pennsylvania Railroad pursued with the T-1 duplex drive development or that New York Central under Paul Kiefer was attempting in similar situation to Wardale with the NYC 6000 series Niagaras. Time was indeed running out.
Dr DWardale however never began development of Poppet Valve gear and its possibilities - surely he was of a mind to achieve much with this potential which Ralph Johnson noted. These were paths of power that steam locomotive design never persued because of the general adoption of diesel electric locomotive design in the 1950's.
You need to look much more carefully at the detail history of poppet valve design and development in the United States. There is more to effective steam distribution than better-flowing valves -- dead space, routing of steam flow in the tracts, and compression control being three. That is before you get into spring return, sealing under a wide range of temperatures, problems with drifting, etc. Note that Wardale and the 5AT organization both have come to prefer piston valves to poppets on locomotives that have to be maintained at lowest cost in regular service, and have explained their reasoning in some detail.
There are also approaches for compression control (simple, like Okadees, or more complex like Jay Carter's approach for steam automobiles) that work just fine for the practical benefits and don't have the 'nightmare box' cost and maintenance issues that OC or RC poppets do. Trofimov valves, as improved by Meiningen, (or Wagner bypass valves) give much of the improvement in drifting that poppets provide.
Where poppets are most valuable is for high horsepower at high speed (see the two variants of the Lima-modified K4 setup). But not much of a locomotive's time is spent in that range. Meanwhile, compare the performance difference -- at the cylinders -- between Wardale's double long-lap/long-travel articulated piston valves, with 'diesel-style' rings (driven by Baker gear with Multirol-type bearings on all pivots) and a typical Lentz or Franklin setup.
Paul Milenkovic,
Very interesting point you have on the "Red Devil" and high exhaust pressure relief into a feed water heater system.
This observation is seconded by Ralph Johnson who was design engineer for Baldwin Locomotive Works in his book The Steam Locomotive.
Ralph saw one of the truely dynamic possible design factors of "poppet valve gear" was the separation of intake and exhaust valve events by removing the symetry of movement Walschaerts valve gear applies to both intake and exhaust piston valve events.
The exhaust valve event cannot be optomized because this would adversly effect the intake event. At close "cut off" valve settings - when Walschaerts would become most effective - it suddenly then ceases to become effective because of the compromise the intake event forces upon the exhaust and the exhaust upon the intake. Walschaerts valve design cannot achieve what becomes possible with steam locomotive power development.
Poppet Valve Gear design - owing to the use of camshafts - on the other hand has a unique ability to have taylored separate valve event for both intake and exhaust.
This fact plus the possibilty internal steam passage streamlining for intake and exhaust passages without the obstruction of the Walschaerts "valve piston" allows ever increasing possibilties of performance in reciprocating steam locomotives.
Automotive type intake and exhaust ports with poppet valves similar to gasoline engines are then a possibility with railroad steam engines.
Here is the Red Devil application of tapping off of high pressure exhaust for feed water heater and condensing effect. Additional added advantages of reducing exhaust back pressure and exhaust nozzel restriction ushers in many other possibilities for firebox and boiler draft and front end smoke box design then become available with this arrangement. Controled and reduced draft force reduced fuel consumption and increased heat derivation. This is where "Red Devil" got much of its unique performance.
Red Devil was a one off and brilliant design at the end of steam production and the discoveries of Wardale in perfomance and economy were not widely known and appreciated by the rest of the world.
Wardale however never began development of Poppet Valve gear and its possibilities - surely he was of a mind to achieve much with this potential which Ralph Johnson noted.
These were paths of power that steam locomotive design never persued because of the general adoption of diesel electric locomotive design in the 1950's.
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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.
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.
ChuckAllen, TX
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.
samfp1943this link as well, might be of interest on this Thread @ http://www.steamlocomotive.com/appliances/feedwaterheaters.php
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
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.
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.
And, as I understand it, roller bearings on the lead and trailing trucks. Why ever not?
BigJim They have installed a feedwater heater on Sou. 4501. https://www.facebook.com/southern4501
They have installed a feedwater heater on Sou. 4501.
https://www.facebook.com/southern4501
Johnny
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 (superheater, feedwater heater, high boiler pressure, condenser) in "failed" attempts to increase thermal efficiency in exchange for greatly increased maintenance expenses.
By that reasoning, the diesel should have failed. According to the H. F. Brown paper in the late 1950's, the diesel indeed had lower fuel costs but counter to established wisdom, and correcting for a worn out old steamer vs a brand new diesel, the steam engine had drastically lower maintenance costs balancing the increased fuel expense.
So what about the feedwater heater? Forward progress in engine efficiency or just another gadget not worth the maintenance expense?
Judging maintenance cost can be challenging as it can be influenced by what Porta called "detail design." Just as there was a wide range in maintenance costs among 1st generation diesel, there was perhaps wider range within steam. In Wardale's Red Devil, the 25-class 4-8-4 steam engine that was upgraded into the single 26-class "Red Devil", the non-condensing version of the 25 had lower maintenance cost by multiples over anything else run in South Africa. How much trouble is a feedwater heater probably depends on "detail design." That and the effectiveness of the water treatement scheme, on which there was a lot of work if not significant advancement in the twighlight of steam.
What kind of fuel savings do you get from a feedwater heater anyway? In rough-round numbers and at around 300 PSI boiler temperature and about 800 F exit temperature of the superheater, it takes about 1400 btu to raise a pound of superheated steam starting with cold water. Of that, it takes about 400 btu to raise the cold water to the roughly 400 F boiler temperature, another 800 btu to evaporate it at that boiler pressure, and another 400 f to superheat it.
As it takes 1 btu per deg F per pound of water, I would say an exhaust steam injector or an "open shell" feedwater heater would save about 140 BTU or an efficiency gain under optimal conditions of about 10 percent. A closed-shell feedwater heater takes steam under pressure through a valve from the exhaust-opening blast and is reputed to be good for another 60 F in temperature increase, giving about a 14 percent savings. This is consistent with what Wardale claims for efficiency gain, but from his tables, his efficiency gain was lower than that in practice.
There is another thing you can do, and I don't know if it requires a feedwater heater as a first stage or not. The economizer.
One version of this was the Franco-Crosti system tried in England and elsewhere, where you piped the mix of steam and combustion gas from stack into a kind of "mini boiler", actually the feedwater preheater or economizer. That system, unfortunately, cooled the hot gases to where they started condensing, and the condensed locomotive exhaust is very corrosive and those heat exchangers did not last very long.
Another version of this was tried by Chapelon on the 160-A1 low-speed freight locomotive. It is also proposed by Wardale on the 5AT project. There, you use a baffle inside the boiler to separate it into a front preheater compartment from the rear boiler compartment. When the combustion gas in the tubes has cooled below 400 F, it cannot boil any more water but it certainly can preheat the water up to 400 F.
This flue-gas economizer seems simple enough, but the detail engineering is always where "the tough need to get going." You may want to combine this with a closed-shell exhaust-steam fed feedwater heater so as to not cool the flue gas to the dew point to wreck the tubes. Such a system could offer a 25 percent savings on heat rate.
What does this mean? The Case for American Steam reprinted on the Coalition for Sustainable Rail web site offers a "water rate" of 13.5 lb/hp-hr for the best of American steam (thermal efficiency-wise), i.e. the Pennsy T1 and those latter-day AT&SF Northerns and a water rate of 12.5 lb/hp-hr for Chapelon's 242-A1 compound, the best-of-the-best French design. With a 60 percent efficient boiler, we are talking 8 percent efficiency for the T1 (heat-to-indicated or cylinder HP and probably under the most favorable conditions), about 9 percent for the 242-A1.
Increase the boiler efficiency to 80 percent with a Gas Producer scheme, we are talking about 11 percent on the T1, 12 percent on the 242-A1. Now add the combination of a good feedwater heater and that economizer baffle in the boiler space and we are at 14.4 percent and 15.5. Finally, use exhaust cylinder steam to power a combustion-air preheater to boost the boiler to 90 percent efficiency, and we are at 16 percent efficiency simple expansion, 17.5 percent on the compound.
Add to that Chapelon's cylinder jacketing from the 160-A1 that extended efficiency over a wider range of piston speed, we are talking something that is competitive with a Diesel in thermal efficiency, considering that the conversion of solid fuel, whether from coal or from biomass to liquid fuel is at best 50 percent efficient.
If steam engine is a dirt-simple machine burning dirt-cheap fuel, however, forget about even a superheater -- go saturated steam.
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!"
Dr DRalph Johnson design engineer for Baldwin Locomotive Works offers a differing opinion concerning the feed water heater designs,
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