I am aware of several attempts to build locomotives with high-pressure water-tube boilers spanning from late 1920s to early 30s, often either using the Schmidt system or a water-tube firebox combined with a fire-tube boiler.
Something I’ve wondered is why more locomotives were never tried with a marine three-drum Yarrow or Admiral boiler. The LNER 10000 used a modified back-to-back Yarrow boiler that from what I know seemed to work well enough but the locomotive with otherwise plaqued with issues such as superheating troubles and feedpipe troubles before the whole thing was given up.
It’s interesting the Yarrow boiler was never tried on another locomotive. I would think in the United States it would have been tried at least once due to a more lenient loading gauge and maybe someone dedicated could have made it work. Why do you guys think it was never even attempted? Was it considered economically unsound as superpower steam reached its peak?
Keep in mind that there were successful watertube designs, not necessarily involving higher pressures. The Brotan design in Europe was probably the most utilized of these; to my knowledge it was not used in North America.
In almost all cases in North America, the design is not for a watertube boiler per se (like a Yarrow); it’s a watertube firebox (to replace staybolted-plate construction with a vulnerable crown sheet and high maintenance requirements including differential thermal issues) which is appended to a ‘normal’ shell-and-tube/flue convection section. These had their own thermal-expansion issues, some of which were solved with improvements in welding technology and inspection, involved considerably more fabrication than conventional ‘Stephenson’ construction, and had sometimes extreme problems with circulation at different levels of turndown (which becomes critical at the high peak firing rates found in large locomotive boilers).
In my opinion, the critical thing that ‘killed’ the adoption of watertube boxes was cleaning and maintenance. When you combine a high evaporative capacity per foot with indifferent feedwater quality (and, later, the presence of chemicals to treat the feedwater, some of which produce solids that have to be frequently or continuously blown down) you wind up with sludge and deposits which have to be carefully turbined down lest they form hot spots with resulting DNB and stress-corrosion acceleration (and more!) There is also an amazing amount of quench in many of these designs, as they aren’t limited to ‘waterwall’ structure but may have rows of tubes in the combustion plume, like syphons, that stop much of the luminous radiation literally cold.
Perhaps most notable among American designs were the Emerson fireboxes applied to B&O power. An interesting approach to economical construction was used on Baldwin 61000 (still available for study in the
Schmidt as in smoketube superheaters, not Schmidt as in terminally high pressure in purified water. Roughly a decade and a half apart.
The thermodynamic craze for extreme pressure on locomotive boilers seems to have started roughly in step with improved metallurgy for power-station boilers, without precisely realizing that the situation on board the locomotives of the day would not be comparable in a great number of respects.
Mind you that high pressure in and of itself did not necessarily hold terrors - Jacob Perkins, building on the work of Oliver Evans, was working with 2000psi pressure (in small-flattened-bore thick-wall tubes) by the 1840s, and his grandson built a yacht (the Anthracite) with a boiler hydro’ed to 4000psi, proofed to 2000psi, tested at 750psi and running reliably at 350psi across the Atlantic in 1880. The generation of engineers who were expected to run the Schmidt-system 4-8-4 on NYC, however, were faced with a very large steam gauge normally reading 850psi, and never did come to like it – this not being surprising after very similar high-pressure tube failures.
Anything higher than 300psi was recognized in the 1920s to involve compounding. This went hand-in-hand with the perceived advantages of three cylinders … in the 1920s. The practical effect of the changes that would make large 2-cylinder engines so good ‘later on’ didn’t really start happening until near the end of that decade.
OK, more than 2 cylinders and compounding superceded by improved 2-cylinder locomotives?
I keep coming back to Wardale’s account of the C&O 614 tests by the ACE people that he relates in The Red Devil. On a BTU basis, he rates the 614 as using 12 times the energy of the SD60 diesels used for coal drags on the same route.
Mind you, Wardale speaks of the host railroad’s attitude towards thrashing the diesels (they were for it), but when I say coal drags, they were really underpowering their trains and averaging 20 MPH whereas the 614 was averagin about 30 MPH. Yes, the faster speed works somewhat against energy efficiency.
Wardale also blames “the poor exhaust system” and “the leaking firebox”, but they were operating a 614 at high loads and low speeds far from where it would get its peak thermal efficiency. Compounding along with multi-cylinder could have gone a long way to producing tractive effort close to the adhesion limit mile after mile, what the CSX was doing with the diesels they were comparing against, with a reasonably efficient degree of expansive working for efficiency. A two-cylinder single-expansion locomotive is just not going to do it in that service.
Keep in mind that the 614T testing was not ‘done’ to determine the thermodynamic efficiency possible out of the J-3 design: there was no air preheat, no feedwater heat, no enhanced firebox-leg circulation, and no feedwater heat. And bad uncorrected leaks in the firebox staybolting, poissibly other places. The purpose of the testing was to develop characteristic curves for Stephenson-style boilers for the Foster-Wheeler people, ASME for example long having had no applicable boiler code for that construction in mobile power boilers.
Even assuming overall-Rankine-cycle efficiency as high as Porta thought possible for “Gen 1” steam, between 9 and 10%, you are still multiples of fuel cost away from diesel, even before you have to incorporate the water consumption, carriage, and handling costs. This was supposedly ‘made up for’ by the cost of the fuel used (which is why the ACE 3000 was somewhat suicidally designed to run on “mine run” coal) but you should not expect any large conventional reciprocating locomotive to be particularly efficient overall, and to this we add the ghastly slow-speed performance characteristics (as commonly ascribed to the ‘misuse’ of the H-8 Alleghenies with substantial consists held to top speeds well below the locomotive’s horsepower peak).
Remember that the effective feature of ‘compounding’ on locomotives is the longer possible expansion from inlet to exhaust. Good modern 2-cylinder engines had an admission pressure essentially limited not by boiler technology but maintenance cost, and an exhaust pressure (with suitable front end) equivalent to that the LP engine of a compound could produce; the only real ‘price’ of saving the complexity and extra cost/maintenance of a compound is that the valve gear needs to be effective at assuring effective ‘long expansion’ regardless of speed and applied load. Enough thermodynamic advantage to overcome the first-cost and maintenance
Keep in mind that the 614T testing was not ‘done’ to determine the thermodynamic efficiency possible out of the C&O J-3a design: there was no air preheat, no feedwater heat, no enhanced firebox-leg circulation, and no feedwater heat. And bad uncorrected leaks in the firebox staybolting, poissibly other places. The purpose of the testing was to develop characteristic curves for Stephenson-style boilers for the Foster-Wheeler people, ASME for example long having had no applicable boiler code for that construction in mobile power boilers.
Even assuming overall-Rankine-cycle efficiency as high as Porta thought possible for “Gen 1” steam, between 9 and 10%, you are still multiples of fuel cost away from diesel, even before you have to incorporate the water consumption, carriage, and handling costs. This was supposedly ‘made up for’ by the cost of the fuel used (which is why the ACE 3000 was somewhat suicidally designed to run on “mine run” coal) but you should not expect any large conventional reciprocating locomotive to be particularly efficient overall, and to this we add the ghastly slow-speed performance characteristics (as commonly ascribed to the ‘misuse’ of the H-8 Alleghenies with substantial consists held to top speeds well below the locomotive’s horsepower peak).
Remember that the effective feature of ‘compounding’ on locomotives is the longer possible expansion from inlet to exhaust. Good modern 2-cylinder engines had an admission pressure essentially limited not by boiler technology but maintenance cost, and an exhaust pressure (with suitable front end) equivalent to that the LP engine of a compound could produce; the only real ‘price’ of saving the complexity and extra cost/maintenance of a compound is that the valve gear needs to be effective at assuring effective ‘long expansion’ regardless of speed and applied load. Enough thermodynamic advantage to overcome the first-cost and ma
Not necessarily in this country, but there are ample markets even in Europe for external-combustion power, and in a number of contexts for ‘renewable’ or clean versions of locomotives technically using those kinds of fuel, for example those burning biodiesel or the kind of highly-torrefied wood proposed Project 130. While the 5AT project has fallen on hard times, there are just as many potential uses for that size and character of engine as there were 20 years ago.
I do think that the Project 130 claims regarding Amtrak-capable power were, shall we say, a little overstated (and I notice that Ward’s approaches have considerably backpedaled from the original claims). For a variety of reasons we have discussed, the original impetus for ‘clean coal’ power that drove the research involving 614T and ‘American Coal Enterprises’ didn’t have much of a renaissance after the artificially-induced fall in oil prices around the Iran-Iraq War torpedoed it in the mid-80s, and it is almost unthinkable now, although some competent organizations known to me continue to advocate and work for that technology as an alternative.
Wardale suggested that whereas a steam locomotive may never be better than some small multiple of a diesel locomotive’s fuel consumption in BTUs, it could be equal to or better than the process of making synthetic fuel out of coal to run a diesel locomotive. If the synthetic fuel plant took 3 BTUs of coal to produce 1 BTU of #2 diesel fuel and an advanced steam locomotive took 3 BTUs of coal to haul what 1 BTU could in a diesel locomotive, you were breaking even, and you didn’t need the expense of the synthetic fuel plant.
The thought was that late-era steam needed 6 times the BTUs of diesels and a doubling of steam thermal efficiency to 3 times diesel was in the realm of what the Chapelon-Porta-Wardale improvements could achieve.
Of course all of this was in the era before emission of CO2 came under regulatory stricture with Kyoto and Paris agreements on forestalling CO2-induced climate change. Whatever you think about the seriousness, urgency or perhaps lack of such of this problem, you are just plain not going to get any government support or even regulatory approval for a scheme that replaces a petroleum-derived energy course with a coal-derived energy source with a 3:1 increase in CO2 emissions. It is just not going to happen.
On the other hand, the US Federal government was contemplating just such a thing of using massive coal reserves to substitute for scarce imported oil in the era of the ACE project. Even Porta and especially the Project 130 people caught wise to an emerging new reality with the idea that, "we will be burning carbon-neutral biofuel, not coal, and the same formula applies to biofuel-to-liquids conversion being equivalent to combusting solid biofuel directly in a steam locomotive of perhaps double the thermal efficiency as late-era US steam.
What had Wardale so glum about the Locomotive Number 614 tests is that the 614 was running 12 BTUs to carry the same tonnage as 1 BTU in a diesel locomotive. Th
One major ‘take-home’ point about the 1980s steam research was that it implicitly involved two things: “energy independence” in the immediate post-Carter years, and perceived cheap fuel translating into cheaper running costs. As those became ‘deprioritized’ all the disadvantages of external combustion at the required large, cheap scale became just as insurmountable as they were historically. You may have observed it hasn’t shut down development of higher-efficiency steam locomotives; you may also have observed that even the more likely applications of it in practice haven’t occurred (the suburban service in Switzerland being a comparatively recent example).
That is not entirely because the technology is unworkable; it’s more because the effective barriers to re-entry, political and economic, are too high, and the risks intolerable to modern institutions. There are other factors waiting should those be overcomable in a particular context, but those are sufficient enough so far, and predictably into the futures we currently predict.
Wardale apparently made the mistake of emphasizing this point to Ross et al. at the wrong time. To this day, bring it up and Ross will strongly react that Porta was the critical design ‘genius’ and Wardale unable to accord with that, or uncomfortable in a “subordinate” position – rather than that he was noting where all the shortcomings were.
To this day, obtaining the results of the 614T testing is a difficult (and, in my case, fruitless) exercise. In no small part this is likely because they are far from representative e
I get that compounding hasn’t lived up to its promise. That is basically what Chapelon was working on because France was all about compounds, and those locomotives weren’t performing as well as they could.
There was evidence that compounds were getting pitifully small amounts of power out of their LP stages on account of nucleate or wall-effect condensation. Apart from his work on lower back-pressure exhaust, streamlining the steam passages, lower-restriction superheaters, increasing direct heating area in the firebox with syphons, although the potential for quenching the luminous flame giving radiative heat transfer has been mentioned, Chapelon’s first approach was applying high levels of superheat so the steam would make it through the HP and LP stages with some superheat left so it wouldn’t condense.
Whereas his 242-A1 fast passenger locomotive gets the glory, his second approach came out of the 160-A1 high-tractive effort freight locomotive. A fuel-efficient freight locomotive is what the ACE project and their various iterations of proposed locomotives were all about. The 160-A1 was set up as a test bed to try different combinations of things, and it seems the “best” setup was to use low or no superheat (helps with valve and cylinder lubrication) in the HP feed but to rely on jacketing the HP cylinders to fend of wall condensation. Condensation in the LP cylinders was to be forestalled by use of a reheater of the IP steam.
I am interest in other sources of technical data on steam if someone can point me to them, but Wardale’s Red Devil book has numbers for limited sets of speed and cutoff. I have converted speed to MPH, the indicated HP at that speed to a factor of adhesion assuming 82 metric tons on drivers for Locomotive 3450, and converted to water rate form kg/kW to lbs/hp.
Page in “Red Devil” Speed Cutoff Factor-of-adhesion Water rate (lbs/h
It did in France, where coal was over “the equivalent of $6.60 per gallon”, and engineers were trained as just that – they didn’t call them ‘mecaniciens’ as a euphemism. There were other factors that enforced low water rate through compounding, such as a relatively low fixed speed limit that stressed acceleration to speed and then fine speed control close to that limit more than absolute high speed potential.
What is perhaps surprising is that so little practical recognition of the effect of this problem was made over the years. The issue is more significant than just ‘condensation’; it’s disproportional pressure over the stroke length, out of ‘sync’ with the HP expansion characteristics.
The effective ‘cure’ for this problem is some kind of proportional injection into the LP to equalize the thrust over the stroke with that practically being exerted by the HP. (There is a kind of parallel for multiple-stage systems like that on the 160 A1, but as I don’t entirely understand the dynamic layout Chapelon used, I can only mention it in the abstract.) This was difficult to do with strictly analog machinery, even in the early 1950s, and by the time digital equipment was properly robust to work on steam power, the emphasis was more toward steam turbines and not simple reciprocating power. Even a slightly ‘improved’ version of the N&W booster valve is capable of reasonable performance in this kind of service … at least in my humble opinion.
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Chapelon’s first approach was applying high levels of superheat so the steam would make it through the HP and LP stages with some superheat left so it
The idea is that you have a fundamental set of valve events, which cause and then induce steam flow (through the ports and passages). Pilot injection involves a small modulation of additional steam which ‘fine-tunes’ conditions in the cylinder for action of the main charge. Note that much of the additional mass flow and timing change required for extreme high speed can be provided via sufficiently-capable (and electronically-timed) injection in addition to what the valves do, without requiring the valve gear itself to be able to source the necessary mass flow at high cyclic/low duration.
In fuel injection, a very small amount of fuel can be injected early in a compression-ignition engine (or a direct-injection engine) to raise the temperature of the air charge through partial combustion and lower the effective compression that has to be derived from crankshaft rotation, at the same time distributing a small amount of ‘promoter’ molecules within the cylinder volume to optimize subsequent combustion reactions, especially when the engine is running at high speed/short combustion duration but relatively high expected MEP.
Pilot injection of steam can be used for a variety of purposes, one of which is to in effect ‘clean up’ the indicated diagram of pressure, another of which is to increase retained compression slightly to give less wiredrawing upon valve opening but maintain overall effective mass flow, another of which is to enhance heat in the cylinder on short cutoff and long expansion to preclude nucleate expansion when operating outside the best ‘envelope’ for valve and cylinder construction.
The N&W booster valve does some of what pilot injection can accomplish, but in the intermediate receiver rather than directly in a cylinder. As