Any locomotive that would be designed today using steam, would look nothing like the steam engines that the diesels phased out. The maintenance cycle would have to be such that other than putting in fuel and steamable fluids (if not a closed loop system) there would be no need for maintenance other than replacing brake shoes and adding sand for the 92 day inspection cycle. Anything more maintenance intensive is a not-starter.
Never too old to have a happy childhood!
Paul,
A couple of quick comments on the Rankine cycle.
One larger contributor to efficiency is that liquid water is nearly incompressible, so pumps can be made to be very efficient. Gas based cycles have to contend with the gas heating when compressed, which provides all sorts of ways for the entropy to increase.
One limit on maximum steam temperature is that the fraction of water that breaks into H+ and OH- increases with temperature. 1200F appears to be the practical limit for steam temperature in order to keep corrosion under control.
- Erik
Relax Paul, I'm just trying to make a joke here.
Honestly, no-one would be more happy than me to see steam come back, in whatever form. Maybe it's possible, maybe it's not. Probably not.
Keep in mind a whole industry that no longer exists would have to be re-created from scratch. It's all gone! Baldwin, ALCO, Lima, all of them. The manufacturing equipment was scrapped a long time ago, the men that built the locomotives are dust, or the very few that are left soon will be, and all the appliance makers are gone too. All that remains are the blueprints.
There's a much better chance of wholesale mainline electrification where feasable than there is a return to steam. Or another power source may be waiting in the wings for some genius to find it or for God to reveal it in His own good time.
But steam? Man I LOVE steam, and I think the world changed for the worse when steam died, but it ain't gonna happen. More's the pity.
Hence my statement that this thread is all fun speculation.
Paul Milenkovic It may not be in 10 years, in may not be in our lifetimes, and it may not be in a 100 years, but at some point, we are going to run out of economic oil ... there may come a time when knowing how to build, maintain, and operate steam locomotives will become essential.
It may not be in 10 years, in may not be in our lifetimes, and it may not be in a 100 years, but at some point, we are going to run out of economic oil ... there may come a time when knowing how to build, maintain, and operate steam locomotives will become essential.
You did not read the references for Oxford Catalysts very carefully. ;-}
It is not difficult to determine the marginal cost for a barrel of syndiesel (or equivalent) prepared via Fischer-Tropsch either from gasified coal or natural gas. It is not difficult to determine the marginal-price range for great extension of the various biodiesel processes -- specifically including algae, which is the only generation technique that does not need to follow Malthusian proportions.
In brief, we are never going to 'run out of oil' as long as there is a cost-effective demand for it, even if as a carrier fuel. There are too many advantages, including the ease of distribution and storage.
The one scenario where I could imagine some type of steam technology being used for railroad traction would be utilizing solid biomass fuel but it's hard to picture that taking the place of fossil fuels.
It probably won't, except for political or witch-hunt reasons. Some of the 'biomass' contenders, notably the torrefied fuels, are primarily intended to work as additives for reasonably clean coal combustion -- economics (including, if you must, 'welfare economics') will determine the operant proportion of biomass above that which produces all the desired effects from the 'additive' components.
I am working on a multifuel system that is essentially a throwback to the very early days of oil firing on locomotives. This uses a GPCS-compatible bed of mixed coal and biofuel, providing baseline output, with some combination of liquid and gas fuel (as needed) through separate burners... which can use the firebed as assistance for continued atomization, flameholding, or maintenance of a zone of gas over transition temperature, and (among other things) eliminate any tendency for sooting or smoking even up to high secondary-fuel mass flow.
Voith is not the only company with fairly-well-advanced Rankine cycle bottoming; BMW had a well-defined one at automobile scale years ago. (Notably, this followed the precedent of their fuel-cell system in being sized for the ancillary loads normally driven off a vehicle IC engine, and not being designed to substitute for the wide-range high-vanity-cushion "turndown ratio" required of a typical automobile engine. Smart!!)
Paul Milenkovic Firelock76 ndbprrWell the reality is steam is totaly impractical. Energy Is lost converting water to steam and more energy is lost converting steam to power. Internal combustion eliminates the steam step making it more efficient on the power side and the exhaust polution side. Steam can't win in any way. Well yeah, we know all that, but this is just fun speculation. No harm in that. Kind of like speculation on "what if General Robert E. Lee had an atomic bomb at Gettysburg?" "Gen'ral Lee, we're losin' sir! What're we gonna do?" "NUKE 'EM!" This nothing like speculating on "what if General Lee" had an atomic bomb. This is like speculating on "what if China develops their missile tech to the point that our Carrier Battle Group Navy is rendered obsolete -- what do we do now?" It may not be in 10 years, in may not be in our lifetimes, and it may not be in a 100 years, but at some point, we are going to run out of economic oil. You live-steam hobbyists, you people exhibiting steam traction engines at shows, all of you operating steam locomotive railroad excursions, all of you arm-chair engineers speculatin' away on trains.com, keep doing what you are doing, because there may come a time when knowing how to build, maintain, and operate steam locomotives will become essential.
Firelock76 ndbprrWell the reality is steam is totaly impractical. Energy Is lost converting water to steam and more energy is lost converting steam to power. Internal combustion eliminates the steam step making it more efficient on the power side and the exhaust polution side. Steam can't win in any way. Well yeah, we know all that, but this is just fun speculation. No harm in that. Kind of like speculation on "what if General Robert E. Lee had an atomic bomb at Gettysburg?" "Gen'ral Lee, we're losin' sir! What're we gonna do?" "NUKE 'EM!"
ndbprrWell the reality is steam is totaly impractical. Energy Is lost converting water to steam and more energy is lost converting steam to power. Internal combustion eliminates the steam step making it more efficient on the power side and the exhaust polution side. Steam can't win in any way.
Well yeah, we know all that, but this is just fun speculation. No harm in that.
Kind of like speculation on "what if General Robert E. Lee had an atomic bomb at Gettysburg?"
"Gen'ral Lee, we're losin' sir! What're we gonna do?"
"NUKE 'EM!"
This nothing like speculating on "what if General Lee" had an atomic bomb. This is like speculating on "what if China develops their missile tech to the point that our Carrier Battle Group Navy is rendered obsolete -- what do we do now?"
It may not be in 10 years, in may not be in our lifetimes, and it may not be in a 100 years, but at some point, we are going to run out of economic oil. You live-steam hobbyists, you people exhibiting steam traction engines at shows, all of you operating steam locomotive railroad excursions, all of you arm-chair engineers speculatin' away on trains.com, keep doing what you are doing, because there may come a time when knowing how to build, maintain, and operate steam locomotives will become essential.
But at what point are we going to run out of economic natural gas? Hint: a LOT longer than the oil reserves..
As far as Rankine cycle bottoming although the railroad industry doesn't seemed to be focused on it there is at least one company offering a system based on essentially 0ff-the-shelf technology.
Voith turbo, knows to some US railfans as the company that provided the Hydraulic transmission system for Espee's Alco built Diesel Hydraulic locomotives, is trying to market such a system:
http://resource.voith.com/vt/publications/downloads/1971_e_g_2161_e_steamtrac_rail_2012-08_screen.pdf
"I Often Dream of Trains"-From the Album of the Same Name by Robyn Hitchcock
If GM "killed the electric car", what am I doing standing next to an EV-1, a half a block from the WSOR tracks?
The Rankine (steam power) cycle, with some tweaks such as a feedwater heater, is pretty close to a Carnot cycle. The Carnot cycle is the theoretical highest efficiency -- subject to a limit on the "hot side" temperature and the "cold side" temperature of the thermodynamic cycle.
The Brayton (gas turbine) cycle is also a pretty close approximation to a Carnot cycle. One key difference with the Rankine cycle is that there is no phase change -- the raising steam from water you talk about. This means that considerable mechanical shaft power from the turbine has to be recycled into running the compressor, to boost the air working fluid in pressure so that heat can be transferred to it at a higher temperature than heat is rejected at the turbine exhaust.
Gas turbine engines live or die on the mechanical/aerodynamic efficiencies of turbines and compressors. This also explains why gas turbine efficiency drops off so dramatically at part load -- as you drop the RPM's on the turbine and compressor, their efficiency as well as pressure ratio drops off.
The steam engine (Rankine cycle) only needs to move a much denser fluid -- liquid water -- from atmospheric pressure in the tender up to boiler pressure. This needs much, much less mechanical power than a gas turbine compressor, whether the water is "injected" into the boiler using a mechanical pump or using a steam-ejector pump (the common type of steam locomotive "injector"). The "supercritical" steam cycles used in some of the latest electric power plants is sorta halfway between a Rankine (phase change) and a Brayton (air -- no phase change) cycle. There is more pumping work, but not nearly as much as with a gas turbine.
OK, what limits the efficiency. The Carnot efficiency, and the Rankine cycle achieves that in a rough round-number approximation, requires as high a boiler temperature as possible, and it requires as low a cylinder exhaust temperature as possible.
So what are the limits on the boiler temperature. Largely, the boiler pressure. Owing to the phase change, boiling adds heat at the constant boiling temperature for that boiling pressure. I came up with a way to remotely measure the pressure in those unclad boilers at these Gas and Steam shows or Thresherees -- I point my remote-sensing infrared temperature gauge, read the temperature, and then look up the boiler pressure on a chart.
What is the limit on the exhaust steam temperature? It is the exhaust pressure.
In a non-condensing steam locomotive cycle, the exhaust pressure can be no lower than atmospheric pressure, hence the exhaust temperature can be no lower than the atmospheric boiling temperature of 212 deg-F. If you ran a steam locomotive at the high altitudes of the Andes Mountains, the ambient boiling temperature is lower and hence the Rankine and Carnot efficiencies could be higher. In practice, however, you always have some exhaust back pressure, so the heat rejection temperature of the steam locomotive is that much higher.
If you have a condensing cycle as in a steam power plant, you can exhaust to lower temperature -- the temperature at which you can cool your condenser -- and a correspondingly lower condenser inlet pressure, which may need compound expansion to realize in practice. Can you use a condenser on a steam locomotive? Apart from there only be a few examples -- the South African Railways Class 25C being the most notable, the question is, to what temperature can you cool your condenser?
The condenser temperature makes a big, big difference on the Rankine efficiency, and power plants like to use a (cold) body of water such as a lake or river. A steam locomotive can only reject heat to the ambient air temperature, which may be higher. But not only that, air is a much poorer heat transfer medium than cool water, so getting even close to the ambient air temperature with a condensing tender requires either very large cooling coils taking up space and weight, or very powerful cooling fans, that are a "parasitic" power load that lowers overall efficiency.
OK, what limits you on the hot side? Basically boiler pressure, and there are a variety of reason why steam locomotives never went to higher-than-300 PSI water-tube boilers, although the Jawn Henry ran 600 PSI in a water-tube boiler, and to the extent that the Jawn Henry had operational problems and was scrapped, I am told they didn't have to do with the water tube boiler.
What else can you do? Superheat, you can use very high levels of superheat. When you do that, you are no longer close to a Carnot cycle -- you have to use very high hot-side temperatures in relation to an equivalent Carnot cycle. But many practical cycles -- gas turbines, gasoline and Diesel car and truck and loco engines, use very high hot-side temps to squeeze out more efficiency.
But what is the limit in a steam locomotive, could you not use "insane" levels of superheat, and Chapelon advocated very high superheat? For one thing, there is cylinder lubrication, but Wardale wrote about cooled cylinder liners to circumvent this.
Here is the situation. In intermittent internal combustion (gasoline, Diesel piston engines), you can get very high combustion temperature spikes -- for very short times, and you cool the cylinder wall with radiator cooling water, the piston by oil splash. A modern Diesel locomotive has a very large radiator, but that radiator is just maintaining cooler cylinder temp than combustion temp and represents a parasitic loss -- there was talk of "adiabatic" engines with ceramic pistons to boost efficiency. That radiator cooling is nothing like the main thermodynamic cycle heat flow passing through a steam condenser.
In continuous internal combustion (gas turbines) you can't get quite the same combustion temperatures as in with intermittent combustion in piston combustion chambers. But there are "tricks" -- mainly exotic metals for the turbine blades to withstand the temps along with compressor "bleed air" to cool the turbine blades -- this is also a parasitic loss that you try to minimize.
Now, in a steam engine, which is external combustion, you have to transmit combustion heat across a tube wall, of either a boiler or a superheater. Even if you have the cylinder lube problem under control with cylinder cooling per Wardale, you have to prevent your superheater tube from burning up or melting, and the question is how high can you (economically) go, but modern power plants are using some exotic allows to push this limit -- would you use them in a steam locomotive that already gives up half the efficiency by rejecting heat to ambient air, whether in a condensing or a non-condensing cycle, in relation to the steam power plant using cool river water.
As to whether steam not being able to win, what doesn't win is external combustion, where the hot-side heat transfer has to take place across a metal surface -- in the internal combustion schemes, the heat transfer is by combustion in the actual working fluid, and you can apply cooling to the back side of metal surfaces as needed.
So why do you need external combustion? To burn coal or other solid fuels, including biomass such as waste wood or fuel crops such as switch grass or perhaps solid waste. The steam locomotive is all about burning solid fuels -- if you are burning liquid or gas fuel, you may as well use a gas turbine or a piston engine.
If you are going with external combustion, there are alternatives to the Rankine cycle -- external combustion closed-circuit (usually helium working fluid) gas turbine, Stirling engine, supercritical (highly compressed) CO2, and so on. I went to a talk at the "U" given by engineers from Argonne Lab under US Navy contract to test the supercritical CO2 engine -- as a possible replacement for the steam powerplant in atomic subs, where you have a condensing cycle, but you use little or not superheat because the hot-side temp limit is where nuclear fuel pellets start to melt.
Your ever-eager Forum participant raised his hand during the Q&A and asked, "I see in your supercritical CO2 engine 3 heat exchangers -- these would be the feedwater heater, boiler, and condenser in a steam engine? The thing is that water is a really effective heat transfer medium, both as a liquid and in phase change between liquid and gas? How is pressurized CO2 on that score." At that point, the guys from Argonne labs all looked down at their shoes, and the one guy said, "Yeah, there is that bit about heat exchangers -- what we are gaining in theoretical efficiency with CO2 we appear to be giving up in heat exchanger losses . . ."
So no, there is nothing impractical about steam, especially if the "design requirement" is external combustion to use solid fuel, nuclear fuel, or even solar heat. The steam power cycle is probably as good as it gets with external combustion, as the Navy kinda found out by giving a bunch of money to study this to the Argonne Labs people. Given that you don't have a supply of river water, L.D. Porta was arguing until the time of his passing that a (refined) Stephenson steam locomotive is as good as it gets to derive traction from solid fuel -- coal or biomass.
If there is a requirement for external combustion, and that requirement comes from the need to use solid fuel, and the conversion of solid into liquid fuel can be an inefficient process in its own right, not only can steam win, it is still the only game in town.
carnej1The railroad industry doesn't seem to agree with you about LNG/CNG fuel as they are pressing ahead to develop the technology given Natural Gas's current price advantages vs. diesel.
I was talking strictly about external-combustion locomotives.
There have been various efforts to develop CNG locomotives for quite some time (remember RailPower's CINGL development?) but only recently (with the gas glut from fracking) has the economics come together. LNG is technically more complex in some respects (here is a Railway Age article that's a good introduction to the subject), and some recent technical advances have made it far more practical. But these largely remain systems with IC engines (combustion turbines or piston engines) and comparatively few even use or propose Rankine-cycle bottoming even though there are comparatively mature systems to do that.
Your point about burning 'much more efficiently' is accurate and correct... and it probably is fair to add that NG fueling can produce "cleaner" exhaust than diesel, with considerably less fancy (and expensive, and economy-reducing, etc.) aftertreatment systems. Clean air was at one time the significant salient advantage for natural-gas locomotives, IIRC.
,
Here is a link to a good article that describes the basic Oxford Catalysts approach.
Note that there are other approaches that utilize both catalytic decomposition of H2O2 to 'direct steam' and the use of ;combustion' fuel/H2O2 to produce steam. A key differentiation is that the Oxford Catalysts team understood early that modulating the average number of steam molecules generated per fuel-molecule oxidation can control the temperature in the catalyst bed and hence the expected service life of the catalyst in a commercial machine such as a practicable locomotive.
In case you wonder why this is 'the best idea you never heard of', the principal issue was, and probably always will be, the ease of producing TATP from even moderately concentrated hydrogen peroxide, combined with the relative ease of diversion in any really practical-scale implementation of direct-steam technology on American railroads. Believe me, I am unhappy about this.
Methanol as a carrier fuel is useful in other contexts, of course, and its use is not limited to direct steam applications. One of the things I have been waiting for is an inexpensive reforming technology, and here it appears to be...
Overmod BoydI haven't had a chance to read all replies,, could it be fired with natural gas or ethanol? It could, but it probably shouldn't be. Ethanol is excessively expensive and has some chemical drawbacks as an external-combustion fuel (some of these are the same characteristics that make it a good racing fuel). It's also relatively lacking in heat content compared to liquids of equivalent volume that have more carbon. Natural gas has a very low heat content both by mass and by volume. You can go with CNG, in which case you have pressure issues, or you can go with LNG, in which case you have refrigeration and condensate issues. The situation is not at all like diesel fuel, where you can essentially slop the stuff around in buckets and not worry excessively about flashpoints, critical-mixture explosions in ambient air, and other more or less nasty things natural gas firing not done via fully sealed pipework can provide for you. Where ethanol -- and methanol, which is easily made from methane -- shine, in potential, is in direct-steam cycles, for example the approach taken by Oxford Catalytics to generate reasonably-superheated steam directlly from catalyzed reaction of fuel with about 30% hydrogen peroxide. I don't expect to see direct steam cycles deployed on locomotives any time soon! RME
BoydI haven't had a chance to read all replies,, could it be fired with natural gas or ethanol?
It could, but it probably shouldn't be. Ethanol is excessively expensive and has some chemical drawbacks as an external-combustion fuel (some of these are the same characteristics that make it a good racing fuel). It's also relatively lacking in heat content compared to liquids of equivalent volume that have more carbon.
Natural gas has a very low heat content both by mass and by volume. You can go with CNG, in which case you have pressure issues, or you can go with LNG, in which case you have refrigeration and condensate issues. The situation is not at all like diesel fuel, where you can essentially slop the stuff around in buckets and not worry excessively about flashpoints, critical-mixture explosions in ambient air, and other more or less nasty things natural gas firing not done via fully sealed pipework can provide for you.
Where ethanol -- and methanol, which is easily made from methane -- shine, in potential, is in direct-steam cycles, for example the approach taken by Oxford Catalytics to generate reasonably-superheated steam directlly from catalyzed reaction of fuel with about 30% hydrogen peroxide. I don't expect to see direct steam cycles deployed on locomotives any time soon!
RME
The railroad industry doesn't seem to agree with you about LNG/CNG fuel as they are pressing ahead to develop the technology given Natural Gas's current price advantages vs. diesel.
Whether the effort goes any farther than Burlington Northern and UP's similar experiments back in the early-to-mid 1990's remains to be seen.
The main reason not to use the fuels mentioned in a steam engine is that internal combustion engines burn them much more efficiently.
The Oxford Catalytics concept is intriguing, do you have a link?
blue streak 1 carnej1 With modern automated equipment the fireman can monitor the firebox and operate the stoker remotely from the front of the locomotive. That was how the American Coal Enterprise ACE-3000 (and related proposals) was designed to operate; https://docs.google.com/viewer?url=patentimages.storage.googleapis.com/pdfs/US4425763.pdf You are underestimating the work of a fireman at the backhead. Watching water level., making sure coal was on all parts of the grate, eliminating clinkers, and many other items others can name
carnej1 With modern automated equipment the fireman can monitor the firebox and operate the stoker remotely from the front of the locomotive. That was how the American Coal Enterprise ACE-3000 (and related proposals) was designed to operate; https://docs.google.com/viewer?url=patentimages.storage.googleapis.com/pdfs/US4425763.pdf You are underestimating the work of a fireman at the backhead. Watching water level., making sure coal was on all parts of the grate, eliminating clinkers, and many other items others can name
With modern automated equipment the fireman can monitor the firebox and operate the stoker remotely from the front of the locomotive.
That was how the American Coal Enterprise ACE-3000 (and related proposals) was designed to operate;
https://docs.google.com/viewer?url=patentimages.storage.googleapis.com/pdfs/US4425763.pdf
You are underestimating the work of a fireman at the backhead.
Watching water level., making sure coal was on all parts of the grate, eliminating clinkers, and many other items others can name
The ACE3000 designers included many of the major proponents of modern steam including Livio Porta and David Wardale.
They designed the locomotive to use modern automated coal handling and combustion chamber/boiler systems based on then current practice in the power generation industry.
If you read the patent I cited in my earlier post it explains why the firebox setup would not require the fireman to handle the same tasks as on earlier coal fired steamers.
Note I am not saying that the ACE3000 would have been able to successfully complete with diesels but I do think it would have been able to operate as designed.
Overmod Firelock76The Germans built some cab-forward coal burners in the years prior to World War Two. However, the engineer and fireman were separated, the firebox being in the back of the boiler by the tender. The information I have (for example Gottwaldt, Streamlined locomotives of the Reichsbahn, p.33, showing the 'Kohlenstaub-Sonderbauart' [the specific/special design for pulverized coal] on 05 003) shows the boiler 'back-to-front' with the firebox adjacent to the cab (and both crewmen together) just as expected. The little door at the 'rear' of the shroud is access to the air compressors, smokebox door, etc., not access fo a 'power compartment' as on N&W TE-1 or Bulleid's Leader. Juniatha will have full mechanical details of how the burner and windbox were arranged; from what I can tell, the feed was from the throat of the firebox (as with some oil-burning practice) but the 'burner' is shown extending the length of the firebox sides. I'd suspect that some version of forced draft via the 'Luftkanal' was supplied, in addition to the more normal induced draft via the stack and whatever overpressure came in by way of the entrained hot air in the fuel mixture. If I understand the setup correctly, the coal supply runs pressurized. A turbine air compressor and air preheater supply hot compressed air to a stoker-like feedscrew, with the coal dust then becoming entrained in the air stream in a mixing chamber -- this was then blown to the burner, the mixture comprising much of the primary air and the fuel together... this would not bode well for leaks, although I'd expect the thermal mass of the arch would keep things lit short of a need for explosion doors. At least I'd hope so. My suspicion is that if all else worked as expected, the violently explosive nature of pre-ground coal dust, and its propensity to stick or 'bridge' with even small levels of humidity, would be reasons against use of the idea. Note for instance that there is essentially no way to access the worm with coal dust in the bunker while the locomotive is on the road.
Firelock76The Germans built some cab-forward coal burners in the years prior to World War Two. However, the engineer and fireman were separated, the firebox being in the back of the boiler by the tender.
The information I have (for example Gottwaldt, Streamlined locomotives of the Reichsbahn, p.33, showing the 'Kohlenstaub-Sonderbauart' [the specific/special design for pulverized coal] on 05 003) shows the boiler 'back-to-front' with the firebox adjacent to the cab (and both crewmen together) just as expected. The little door at the 'rear' of the shroud is access to the air compressors, smokebox door, etc., not access fo a 'power compartment' as on N&W TE-1 or Bulleid's Leader.
Juniatha will have full mechanical details of how the burner and windbox were arranged; from what I can tell, the feed was from the throat of the firebox (as with some oil-burning practice) but the 'burner' is shown extending the length of the firebox sides. I'd suspect that some version of forced draft via the 'Luftkanal' was supplied, in addition to the more normal induced draft via the stack and whatever overpressure came in by way of the entrained hot air in the fuel mixture.
If I understand the setup correctly, the coal supply runs pressurized. A turbine air compressor and air preheater supply hot compressed air to a stoker-like feedscrew, with the coal dust then becoming entrained in the air stream in a mixing chamber -- this was then blown to the burner, the mixture comprising much of the primary air and the fuel together... this would not bode well for leaks, although I'd expect the thermal mass of the arch would keep things lit short of a need for explosion doors. At least I'd hope so.
My suspicion is that if all else worked as expected, the violently explosive nature of pre-ground coal dust, and its propensity to stick or 'bridge' with even small levels of humidity, would be reasons against use of the idea. Note for instance that there is essentially no way to access the worm with coal dust in the bunker while the locomotive is on the road.
I think Firelock was referring to these two much earlier locomotives:
http://www.aqpl43.dsl.pipex.com/MUSEUM/LOCOLOCO/KPEV/prussian.htm
The 4-4-4 was rebuilt without the forward cab. I don't know whether the tank locomotive was similarly rationalised.
M636C
Modeling the "Fargo Area Rapid Transit" in O scale 3 rail.
The German innovation's description causes me to ponder:
Did they reinvent the Camelback, the Mother Hubbard, countless Anthracite burners?....rarely called saddlebacks....that isolated the fireman at the rear and could have been designed to put the cab further forward.
Thanks for the comments that included the ACE3000 pics.
I think the article included another, different, interpretation of the ACE in concept art.
blue streak 1 If it were an oil burner it would be a variation of the SP cab forward locos. Probably have a EMD or GE style collision posts and nose . With the smoke stack behind much better for tunnels. A coal burner might be built the same way but it would take a very long stoker system to provide coal to the front of the cab for the firebox. certainly have MU cables for diesels behind and or a second unit. . Smokestack of first unit would be close enough to second unit to drive smoke and cinders over cab ? Since most CP and yard turnouts are designed today ffor diesels a more practical arrangement might be a 4-8-4 or a 6-8-4 ? A 4-8-8-4 would be severely limited as to where it could operate + the size of turntables or wyes.
If it were an oil burner it would be a variation of the SP cab forward locos. Probably have a EMD or GE style collision posts and nose . With the smoke stack behind much better for tunnels.
A coal burner might be built the same way but it would take a very long stoker system to provide coal to the front of the cab for the firebox. certainly have MU cables for diesels behind and or a second unit. . Smokestack of first unit would be close enough to second unit to drive smoke and cinders over cab ?
Since most CP and yard turnouts are designed today ffor diesels a more practical arrangement might be a 4-8-4 or a 6-8-4 ? A 4-8-8-4 would be severely limited as to where it could operate + the size of turntables or wyes.
Why would you need a stoker that goes all the way to the cab?
Per Blue Streaks comment:
A cab-forward wouldn't necessarily have to be an oil burner. The Germans built some cab-forward coal burners in the years prior to World War Two. However, the engineer and fireman were separated, the firebox being in the back of the boiler by the tender. How'd that work out as far as co-ordination of effort was concerned? I don't know. Possibly not too well, German steam that survived into the sixties seemed to be of conventional layout.
Paul Milenkovic Should I start a new thread on "combustion processes" or would that result in the TLDR and MEGO effects?
Should I start a new thread on "combustion processes" or would that result in the TLDR and MEGO effects?
Not to ME!!! ;-}
OK, I get the sense that "the big boys" use pulverized coal combustion. The coal is ground up to the fine consistency of face makeup and then blown into the firebox with compressed air, where it burns like a gas flame -- there is little smoke, no cinders or "carbon carryover" to lower efficiency.
There's more to it than this, including the type and configuration of boiler that works best with this (and with the Cyclone variant of solid-fuel firing). Part of the story is very large size; part of the story is long-period stable operation at baseline load that requires little if any turndown from design conditions; part of the story is lots and lots of packaging space for aftertreatment, air preheat and economizer operation, etc.; part of the story is generally easy access to AC power to drive auxiliaries/ancillaries... electric motors generally being much more effective than small turbines or whatever.
One reasonably successful method of pulverized-coal firing on locomotives was the version of StuG that was tested on Victorian Railways. As you know from reading the Red Devil, Wardale thought that the next logical step beyond GPCS was some variant of PulC firing... I would argue with some intermediate-size fuel form factor, larger than conventional pulverized 'fines', but probably not as large as the 'pellet' size for some of the torrefied additives. There are still some difficulties involved with flameholding, the extreme turndown ratio endemic to normal railroad operation, etc.
With regard to operation of GPCS:
... [The] hydrogen and carbon monoxide then ignites when "secondary" combustion air is introduced above the grate.
Well, not exactly, and therein lies the 'rub' of the gas-producing system. (It is beneficial to study what the reaction conditions through the flame plume in a conventional locomotive boiler are when looking at various firing 'improvements', btw)
First, the 'ignition' presumes that the transition temperature is high enough, and the energy uptake high enough to make transition, to achieve combustion. Second, the ignition presumes adequate mixing of the secondary air with the gas plume to achieve full 'stoichiometric' equivalent... ideally without introducing too much excess air. Third, we still need to account for the behavior of the atmospheric nitrogen; in particular, we can't heat it excessively or it will give us NOx pollution even at fractional-atmospheric ambient pressure.
I also have a grim suspicion that Porta's 'cyclonic' combustion chamber arrangement actually has flow patterns different from those he expects, especially at high turndown and during flow-transition between low and high turndown.
I don't get the sense that Fluidized Bed Combustion is any time ready for steam locomotives as it takes a day-long startup procedure to get stabilized.
I've seen the artist's conception. It looked like a cross between an SD-70 and a Pennsy T-1, that is a modern cab unit with a duplex running gear. I'll see if I can find a picture somewhere.
OK, here ya go...
www.trainweb.org/tusp/ult.html
Wasn't there an accompanying artist's conception of what Ross Rowland's C&O 614 would have metamorphosized to if those ACE 3000 experiments proved out?TRAINs mag, decades ago?
A cab-forward 4-8-4, somewhat covered-wagonish-looking, EMD F-unit cab?
The Porta Gas Producer Combustion System (GPCS) was mentioned -- what does it do and how does it work?
According to Wardale's Red Devil and Other Tales of the Age of Steam, the problem with lump coal combustion on a firegrate, the standard steam locomotive system, is that as the lumps burn down, they get entrained by the flow of combustion air coming up from the bottom through the grate, and they are swept out as "sparks and cinders" through the boiler tubes and out the stack. Besides setting lineside fires (a problem in arid South Africa), the "carbon carryover" makes everyone's clothes dirty, and it is a substantial waste of fuel. At the "grate limit", fully 50 percent of the fuel goes up the chimney, contributing to the very low thermal efficiency of steam engines. If you could prevent carbon carryover, theoretically you could double overall thermal efficiency.
The Gas Produces system operates with a thick firebed and a greatly restricted flow of "primary" combustion air coming up through the grate. The idea is that such an oxygen starved fire turns coal into hydrogen and carbon monoxide, especially if some spend exhaust steam is fed into the firebed. That hydrogen and carbon monoxide then ignites when "secondary" combustion air is introduced above the grate.
That is how it works. What it is supposed to do is greatly reduce the carbon carryover problem. Because the primary air is greatly restricted so the coal bed doesn't as much as burn but acts as a "gas producer", there is much less force trying to lift the particles in the coal bed out the chimney. So the "gas producer" is not that you are turning the coal into gas to have a gas fuel. Rather, you are trying to combust the coal in two phases -- the first phase of solid coal in contact with restricted combustion air to produce combustible gas, and the second phase of the gas rising from the firebed burning in contact with the secondary air, introduced above the firebed where it cannot do the mischief of lifting the burning coal particles off the firebed and out the stack.
The (Red Devil) is in the details. Porta developed the idea and got it to work with these narrow gauge steam engines operating in far southern (i.e. cold part of) Argentina. Wardale took those ideas and tried to get them to work on two steam engines in South Africa, one of them being the famous Red Devil, and tried to get it to work on a QJ locomotive in China with what charitably be called "mixed success."
Wardale reported that the Gas Producer System was technologicaly beautiful -- when you could get it to work. His take was that it was much more efficient with greatly (reduced) carryover when he got it to work, but getting it to work depended greatly on just what coal you were burning as well as educating the crews on the correct procedures, that included such things counter to their training of piling on a thick firebed and leaving the firedoors at least partly open at all times to get enough secondary combustion air into the firebox. It also took longer to build up a firebed and get it into stable Gas Producer operation -- you writes of one fireman who just piled on a bunch of coal, resulting in a big blast when it generated enough gas to flash-over -- on one was hurt, but it gave a scare.
In China, the coal was so bad -- "rice coal" -- mainly small friable particles, that he couldn't get good gas producer firebeds, even in static tests of locomotives with the drive rods removed. He thought that the reason the Chinese were even able to burn this coal at all is that had something akin to a "slag tap" combustion system going -- they had enough molten clinker on the firebed that when they stoked this coal, it would stick to that slag and not get carried off. Maybe Wardale, with more resources, have tried to understand what the Chinese were doing and try to improve that.
Paul of Covington What about the equivalent of pneumatic drill motors (much bigger, of course) driven directly by steam and geared to the drivers, much like electric motors are?
What about the equivalent of pneumatic drill motors (much bigger, of course) driven directly by steam and geared to the drivers, much like electric motors are?
I too have wondered about steam motors driving individual axles.
My office neighbor from a couple years back taught the course on electric drives, and he did research on electric drives of the type his industrial employer used in airplanes. These direct electric drives are meant to replace the "wet" hydraulic system in airliners and their high maintenance expense. He thought that electric drives will "replace everything" and I tried to educate him about the need for quill or even Cardan shaft mechanical drives, from the electric motor, to reduce track impact in high-speed trains.
At least with an electric motor, you just need to supply a pair of wires, and if those wires are thick enough, which is usually not a limiting factor, those wires can bend as needed around corners.
With steam lines, you have both heat loss as well as fluid resistance to worry about when you start running steam lines all over the place. In the usual 2-cylinder rod-drive steam locomotive, you have short and fixed steam lines and exhaust lines, and it is fairly easy to make them low heat loss and low fluid resistance.
The minute you go to a divided drive of any kind, articulated locomotives are a simple version of the steam motor idea, things get really complicated really quickly. I just returned the book on the H-8 Allegheny to the State Historical Society library. The 6-drivered Alleghenies replaced a fleet of 5-drivered plus trailing truck single-axle booster locomotives that the railroad assigned the same tonnage rating. The divided-drive Allegheny with two 3-axle engines may have pounded the track less than the single 5-axle engine, but hoo boy did you have steam pipes going every which way!
Wardale talks up the Garratt as the "answer" to meeting the Diesel challenge by 1) having more powered axles like a Diesel, and 2) having a completely unobstructed ashpan to address some of the concerns I expressed in a prior post. But then he looked at a South African Railroad Garratt, the GMA/M class imported from England, I believe, and he explained that the coal and water consumption were really high, and the pressure drop from superheater header to cylinders and then exhaust backpressure from cylinder exhaust back to the blast pipe were really high. I am wondering whether steam power can tolerate really long steam pipe runs and be efficient.
My high-speed reciprocating jack-shaft drive steam engine concept, where a high speed piston engine turns a jackshaft (a crank, really) that is coupled with straight rods to the drivers is 1) meant to get the low dynamic augment of the S-2 and other rod-drive turbines by eliminating the angling rod off the crosshead, and 2) keeps the steam and exhaust passages short.
My divided-drive version of this has two sets of high-speed piston engines, back to back, one driving a set of drivers under the boiler, the second driving a forward set of drivers under a water tank as in a Garratt. Per Wardale's Garratt proposals, that water tank would be an emergency water reserve kept filled to maintain traction, and water would be drawn down from a trailing tank car as done with the GMA/M. This leaves the ashpan unobstructed by a trailing truck, and the coal tender would be supported by carrying axles and be articulated with the locomotive to stabilize the tracking. Both sets of steam engines would have short steam and exhaust pipes.
zkr123 If someone was to create a steam locomotive with today's technology, what would it look like?
If someone was to create a steam locomotive with today's technology, what would it look like?
It would look like this:http://www.5at.co.uk/
So, what is the combustion system of a steam locomotive, and what difficulties does it have?
A steam locomotive burns coal fuel on a firegrate at the bottom of a waterwall firebox. One problem is putting fresh coal on the grate to feed the fire. Owing to the high combustion rates and high rates of drafting of the combustion air required for the compact boiler on a steam engine, in relation to its heat rate, you have to get the coal spread evenly. If you get thin spots, cold air comes through and it does bad things to your boiler like cause differential contraction of tubes that cause water leaks, very bad.
One solution is to have a skilled, able-bodied crew member, the fireman, shovel the coal onto the grate. A second solution is to have a steam-driven stoker sprinkle coal on the grate. You still need a crew member to operate the stoker and keep an eye on the boiler pressure and water levels and anticipate changes in steam demand by seeing what the engine driver is up to, so you don't clog the fire, allow thin spots instead to develop, waste steam by popping the safety valves when the pressure limit is reached, stall out on the road by letting the pressure drop, and yes, kill yourself and your driver by letting the water-wall water level drop that the firebox overheats and blows everything up in a water-flashing-to-steam explosion.
You also have to remove ash from the firebed so it doesn't choke the fire. That is done by 1) letting the ash simply fall through the cracks between the firebars and fall into the ashpan, 2) agitating (rocking) the grate with a handle-driven link to encourage the ash to fall into the ashpan, 3) dumping all or part of the firebed into the ashpan using that handle and starting over with a fresh fire with fresh coal.
On top of all that, if your fire is hotter than the coal-ash melting (fusion) temperature (the coal ash is actually the non-combustible rock mixed in with the coal as they mine it, and that rock can melt depending on the type of rock formation). That melted ash can resolidify, creating these glassy rocks called "clinker." If too much clinker forms, the combustion air is choked off, the fire dies down, the boiler pressure goes down, and the locomotive slows down and come to a stop. On the "high iron" main line. With following trains. The clinker can be broken into pieces that will fall into the ashpan with a long poker thrust through the open firedoor, but that is hard work. Locomotive crews and especially firemen just hate clinker.
And then there are the cinders and the "carbon carryover." According to Wardale, the smoke you see from a steam engine is regarded as pollution, but it is really a minor waste of coal, mainly soot formed from incomplete combustion of the liquid part of the coal, the coal tar. The big waste of coal is the carryover in the form of cinders. Especially at high steaming rates at full power, the combustion draft lifts the burning coal particles when they burn down to a certain size, and those flaming "sparks" or "cinders" are swept through the tubes, where they wear things out, and out the stack, where they annoy people. Like the people at trackside whose property is set on fire. Or persons wearing white shirts or hanging laundry to dry near the tracks. Or the accountants who see the coal expense. A stoker is said to make this worse as the work conveyor can grind up the coal into small particles, and these particles are sprinkled on top of the firebed, where they can be swept out the chimney before they have a chance to burn.
So before you even see the relative cost of burning a lot of coal vs a small amount of expensive oil fuel, or whether the track pounding from the drive rods is worse than the pounding of axle-connected traction motors, you see why railroad management and the crews working for them like Diesels.
Paul Milenkovic:
"I have been wondering of a high-speed multi-cylinder steam piston engine could be coupled to the wheels with that same electric-locomotive style jackshaft drive."
I am no expert on steam engines, and I don't know much about the details of how pneumatic tools work, but your mention of a high-speed multi-cylinder steam piston engine got me thinking. I've long been impressed with the speed and power of pneumatic tools in such compact packages. What about the equivalent of pneumatic drill motors (much bigger, of course) driven directly by steam and geared to the drivers, much like electric motors are?
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