Paul, I had the opportunity of studying some Porta Papers, among them the one he gave at the Paris Millenium meeting. According to a participant of this meeting he gave a paper looking back at Chapelon's 240.A and .P: he promoted a more fully reconstruction (more like a new built using old parts) as a three-cylinder compound with - naturally the HP inside. Outside LP cylinders were dimensioned so outlandish as to make full ihp (due to boiler limits) at around 10 % c/o (full throttle). That immediately raised the question in me what c/o he would think for 1/2 nominal output or less? I got the answer when reading he even proposed to go 'shorter than zero' i e go over neutral point into backwards for forwards running and claimed he had done that with one of his rebuilts and it worked "fantastically" (quote)! Now, what happens if you go 'over the limes'? Valve travel filling will shorten further and lead will increase! Yet there is a small margin where this could work because the expansion section of work still goes in the forward direction, it only works above a certain speed because it needs to overcome the countering process at the increased lead section. Mechanically this is more like the diesel engine works with a very pointed impulse of thrust - very hard running, thus. Mind that for a small output you submit the engine to full piston thrust and possibly a negative thrust towards the end of piston travel because of extreme expansion going even below atmospheric pressure - and of course due to the excess lead filling. Mechanically this would be abusive for a steam locomotive with her extremely large piston thrust as compared to any other engine, same power output each.One might ask how this enormous LP piston will be supported by the - rebuilding! - given main pin on the drive axle? To that Porta gave a most remarkable answer, in principle saying that "steel doesn't age" and there was "no need to keep designed loads below its full tensile strength" - and consequently he presented his own method of lengthening the stroke on a given wheels and pins material: turn down the diameter of the main rod pin asymmetrically towards the outer side. So, now he had a step between the pin section of the coupling rods that remained original and the turned down pin of the main rod with the already increased piston force and somewhat increased stroke. My informant said there were several in the audience who later discussed 'the wisdom' of such proposals and he himself had quoted the Wöhler curve for strength of steel against increasing numbers of stress reversals. Everybody who knows that curve knows what to think about this bold advance of Mr. Porta's. The same goes with his suggestion "He" can get 1000 psi (70.3 kp/cm² / 69 bar) out of a staybolted firebox. The question immediately pops up: how long until it blows up?It is true that with the advent of feedwater treatment it was possible to avoid scale incrustations and that was a major step towards application of higher boiler pressures. There is however another point to consider with increased pressures, that is hot shortness of steel due to the - also - increased boiling water temperature! So with the use of suitable sorts of steel and full welded construction of an advanced yet principally conventional type of steam locomotive boiler I can see 18 - 20 bar / 261 - 290 psi instead of 16 bar / 232psi, or 25 - 28 bar / 363 - 406 psi in fully new construction to be used but not near three times as much or other fever fantasies such as overcritical water / steam (over 220 bar / 3191 psi and over 374 °C / 705 °F) way out of a suitable range for application in a moving vehicle.
On the other hand, 20 % of overall thermal efficiency seems to be just attainable with compounding and re-superheating if all components are designed to best thermal functionality - a point which is often missed: it is surely not enough to just throw in some exotic type of apparatus and expect it to make the difference. Exotic, non-used, or never over experimental use call for even higher degrees of careful, thoughtful design and still contain a larger degree of failure than types more often used or standardized.
That is the simple reason why so many steam designers shrank from applying even known yet not often used types of machinery or such not in use by their company.
Perhaps I can post the side elevation of that Hudson type four cylinder compound design with 20 % overall efficiency - if there are enough requests to make me plunge into my files, search for it and hopefully and uproot it.
Or, I may post my own design of an eight-wheel high drivered type four-cylinder de Glehn compound - the first three varying layouts in two w/a, 4-8-4 and 4-8-2, of it I made in 1992 at the age of sixteen; in her final version, as a Mountain (by w/a) type with a European standard w/a 4-4 tender, she at least doubled the overall efficiency of some better late hour classic steam designs that have been.
Or - on quite the other end of power output I could retrieve the 0-6-0 with a six wheel tender, a practical plan to rebuild one of Meiningen's rugged and solid fireless (without tender) built in the 1980s with a special design boiler of high water capacity to work industrial plants variably with / without firing for a whole day without replenishing supplies. I found it quite a cute design and a realistic proposal but the director of the Meiningen workshop didn't know how to promote it and, frankly, wasn't half interested in venturing for something new - they rather continue their same old standard procedure overhauls of existing preserved steam engines. This repeated the other major reason why steam had to be replaced - it didn't much proceed anymore!
I'm going to cut it here or I could go on till next morning and fall from the keyboard right into bed - don't do me that!
Juniatha
Paul MilenkovicMy idea on the use of those things for propulsion was not to try to match the firing rate of a monotube flash boiler to the varying steam demand of a railroad steam locomotive. Rather, it would be to cycle such a steam generator on and off to feed a pressure vessel in the style of a "fireless cooker." That could eliminate the uncovered crown-sheet BLEVE explosion hazard of the staybolt firebox.
First, we might as well assume typical SG pressure range: no exotic German high pressures and distilled water; second, the only sensible regimen for much of the "SG's" feedwater is to recirculate the water mass in the 'boiler' (at overcritical pressure and corresponding temperature) through what is essentially a steaming coil throttled on and off between appropriate limits -- you could harden a Raspberry Pi with an SD card and do the necessary firing optimization, avoiding what is now near- rocket science tinkering with restoring weary and expensive Vapor-Clarkson pumps and blowers and spark and relays and stuff. The catch is that you need sufficient overpressure to sparge adequate steam mass flow through adequate volume to make up both the thermal and work 'losses' in the engine and 'boiler' even if well-insulated, so you need a somewhat hefty BFP equivalent, whereas the Lamont equivalent would do the makeup circulation at near throttle equilibrium pressure (with steam separation done positively off the circulated flow in centrifugal separators) -- happily using simple coils containing fast-moving water for the thermal uptake as in a waterwall firebox and getting around the fun of arranging liquid-fuel firing around a complicated arrangement of quenching tubes for intermittent high turndown...
The thing about a Vapor-Clarkson is that it runs on electricity, and it has a number of complex proprietary parts and fabrications. It also requires fairly well-refined fuel, which it burns with the usual external-combustion losses. One might argue that by the time you arrange power to run the blowers and pumps and ignition, you might as well just use a small genset burning the same fuel... and electrical storage instead of all the problems with water transmissions.
The Lamont can run with solid fuel and careful damping, and at least in theory could use a small chain grate to simplify modulating the effective firing rate. I never got to the point of seeing if a Cunningham-style jet pump arrangement would give full circulation, primarily because it made too much sense to run other auxiliaries with OTS electrical motors drawing far more power than the ~3hp for 120,000lb/hr so why not use redundant electric circ pumping -- but for this size application and heat recovery rate, the jet pump ought to work just as it does for water legs in a comparable firebox structure. Something like a formed and welded Jacobs-Shupert construction would furnish all the 'explosion-proofing' you could possibly want, and be easy to clean and NDT inspect...
Prior to HEP, non-steam passenger locomotives had steam generators. These were saturated-steam monotube flash boilers. They were supplied untreated water, and they relied on a continuous blowdown system.
They could not have been that serious a maintenance headache, otherwise railroads would have kept steam locomotives for passenger trains needing steam heat?
My idea on the use of those things for propulsion was not to try to match the firing rate of a monotube flash boiler to the varying steam demand of a railroad steam locomotive. Rather, it would be to cycle such a steam generator on and off to feed a pressure vessel in the style of a "fireless cooker." That could eliminated the uncovered crown-sheet BLEV explosion hazard of the staybolt firebox.
Or did diesel locomotive "steam generators" blow up and kill engine crews?
My point about the small size of the LVM-800 is that, yes, it had a lot of the high-tech Porta was "pushing" but without the condensing and with that inside-connected double cranks for syncronizing the two drives. Yes, it had a crank axle, but how hard is that if you have less ambitious ideas of the amount of torque to apply?
The concept behind the 3 cylinders is compound expansion, and the idea there is to obtain high expansion at near maximum torque, and we have debated on whether that was possible with a two-cylinder simple or perhaps even a two-cylinder compound with the type of "IP injection" you have talked about.
Porta long advocated for compound expansion for getting thermal efficiency near maximum torque, something the Wardale didn't seem to "get" based on Red Devil and the 5AT site essays. I "got" this concept looking over Porta's claims of thermal efficiency for a planned triple expansion locomotive, yes, claiming he could get 1000 PSI pressure out of a staybolted firebox. His "engine map" showed a big fat region of 20% thermal efficiency that would be impossible to get without compound expansion. You could get enough expansion with, say, poppet valves and short cutoffs, but you would only get that under low load.
As to the state of industrial infrastructure in 1990's Cuba, was Porta over-idealistic in his thinking. In his Postlude to Red Devil, he mentions one of the Latin American countries that he regarded as too backwards for what he regarded as the rugged nature of his technology. Do you think he got a false impression from the Cuban counterparts he talked to?
The thing about the Cuba project is that unlike the U.S. were things get "gold plated" with too high a level of technology, Porta seemed to think that he was running the show, unlike the ACE project that was pushing tech that Porta thought was A Bridge Too Far. Porta was able to build "Argentina" with him specifying everything.
Is modern Cuba that tech impoverished that Porta couldn't get workers to make a proper weld to his specifications? Maybe you have input from other steam projects in Cuba that this was the case.
If GM "killed the electric car", what am I doing standing next to an EV-1, a half a block from the WSOR tracks?
Paul MilenkovicOther nominations go to Wardale's Red Devil locomotive in South Africa...
... the ACE 3000 project that never advanced beyond the Vu-Graph stage in the U.S. ...
I would have been interested to see what the Foster-Wheeler engineers actually came up with out of their 'research' on 614T to work on the ACE 6000 or 8000 or whatever fantasy rating the ten-coupled locomotive was intended to be. Certainly there was discussion about it being 'fast' the way the 9F was supposed to be fast... just with an ever-so-much higher center of mass, and not particularly careful consideration of steering the back end of the chassis. If you wanted a practical reciprocating locomotive on that general scale, the 'right' answer is very much more like a Y6c with Chapelon's-style modulated IP injection to balance out the engines at 45-50mph road speed...
What is interesting about the proposal is that it didn't hold back -- 360 PSI boiler pressure with a staybolt firebox, 3 cylinder compound expansion, low-pressure cylinder steam reheat, feedwater heater, smokebox "economizer" (2nd stage feedwater heater), combustion air preheater and a cyclonic firebox to minimize particulate emission.
The 3-cylinder arrangement required a cranked axle, but may there is lower risk of this thing breaking in this lighter duty application?
[/quote]ALCo build 3-cylinder simple expansion locomotives culminating in the 4-12-2 Union Pacific type, but Alfred Bruce writes that this was always regarded as a maintenance and a catastrophic failure concern?[/quote]In my opinion it is practical to make a proper big end for a modern 3-cylinder simple that will hold up properly, be at least as 'maintainable' as outside roller rods, and be reasonably proof against unexpected (or catastrophic) road failure. What changed, in my opinion, was the state of the art in balancing post-Eksergian, which allowed nearly all the effective advantages of three-cylinder drive in an outside quartered two (or four) cylindered arrangement at 'permissible' levels of augment for North American operation. You need to look at little more than what the T&P treatment on the early 2-10-4s involved to understand that any benefit three cylinders might have had wouldn't outweigh the maintenance and servicing concerns (and indeed it is almost impossible to find a three-cylinder engine in the United States that was not expensively rebuilt to two cylinders in the era anyone in the United States cared...)
As to trying every advanced steam idea Porta could think of, maybe the better to do this on a small locomotive than something road-engine scale?
Switch engines are notorious for burning through a lot of coal on standby, but Porta thought that with enough cylinder insulation and with damper-controlled air to the firebox, he had this problem licked?
Now with proper liquid firing, including with liquid carrier fuel synthesized from biomass, something far more interesting becomes possible. Even small flame holding-scale firing mass flow can be arranged to do the same job as the electrical elements on the 8055 2-10-0 -- in fact the Dickens-Barker burner on 4014 can be observed to hold 300psi with normal 'idling' auxiliary demand on natural draft with damper blocks set. (If Ed starts having a whistle fest he does, in fact, need to crack the blower open a tad...)
Were a modern mechanically-atomizing pressure burner to be used, I suspect even a flutter-type burner could be used for appropriate standby.
The peak steam demand was to be something like 11,000 lbs/hr. I had suggested that a diesel locomotive train-heat steam generator could do this in one of its larger sizes?
If you wanted to go with light oil firing, such a thing could be hooked up to a "fireless cooker" steam storage locomotive?
The idea behind the LVM-800, however, was to burn at-hand biofuel such as sugar cane "bagasse" and other ag waste. I am wondering if this thing was intended for single-crew operation, maybe the crew member preparing the fire during standby and then operating the locomotive for short "pulls" in switching service?
The problem with the LVM-800 only began with its optimization for bagasse being the lettering of 'BIOMASA' on a strategically-placed bunker drawing. We had an extensive discussion on more than one occasion on the Yahoo steam_tech list, where a couple of participants had extensive firsthand experience with bagasse firing, and they were not at all sanguine that the trick would work even with top-notch training and oversight. The idea of a cyclonic-firebox installation at high pressure in Cuba, the land of the repeatedly bead-welded throatplates, verges on the terrifying. If I recall correctly, until recently not one 'correctly-calculated' Lempor remained in actual service -- and a couple of the attempts were true whoppers, discussed only off-the-record in somewhat hushed, if occasionally profane, language.
That there is a role for small steam power, especially in regions where intelligence can be developed but capital is scarce, is undeniable. But that it would be relatively "thermodynamically uncomplicated" also follows in many respects -- I would be much more inclined to follow Tuplin on the 'outline' of that type of power than LDP (and I don't say that out of any disrespect).
Minimum practical bound and maximum unit size for 'mainline' modern steam converge in a remarkably narrow range: somewhere in the two-high-horsepower units MUed cabs-out range. Smaller and the packaging of the fixed plant and poorer thermo make the thing too much of a compromise even if fuel is cheap and its lifecycle handling cost-effectively outsourced; greater than that and your water rate becomes impossible or your condensation becomes a vast pain.
In the middle of large and small steam power is the demesne of the 5AT, and here an enormous 'leg up' is that Wardale has done the complete example set of FDCs for a locomotive of this size and characteristics. It would be relatively simple either to reduce complexity for a simple and cheap design, or improve certain aspects for specific applications including high useful road speed. The catch here of course is all the money to be spent for something on the small size for the money it will cost.
Personally I was proud of the final state of the Turbomotive 2 project just before Alan Fozard dropped it to join the 5AT group; there were a number of relatively simple modifications to give a good range of working power with minimal low-speed tip loss etc. I would be tempted to note that even a variant of the Westinghouse two-speed planetary would solve much of the problem-child PRR S2 issues, if you just have to retain side-rod drive to coupled wheels.
Note that some very interesting things happen with steam-generator packaging with Plate H clearance, including effective steam separation at high mass flow both from Lamont separators and a completely-filled convection section a la HRSG.
Let me take up some of the detail points in a following post.
I nominate L. D. Porta's LVM-800 (translates from Spanish to Modern Steam Locomotive, 800 Hp).
LVM800 - "Prometheus Project" (martynbane.co.uk)
This was a project in Cuba in the late 1990s that ended with the passing of its principal engineer in Cuba.
Other nominations go to Wardale's Red Devil locomotive in South Africa, the ACE 3000 project that never advanced beyond the Vu-Graph stage in the U.S. and the improved QJ class in China that Wardale had a role in developing.
What is special about the LVM (Locomotora Vapor Moderna) is that instead of "replacing the diesel" in mainline Class-I road service in the U.S. as the ACE3000 intended, this was meant as an industrial switcher/light branch line locomotive. Its much smaller scale and the setting of less ambitious sights made its development more realistic.
The 3-cylinder arrangement required a cranked axle, but may there is lower risk of this thing breaking in this lighter duty application? ALCo build 3-cylinder simple expansion locomotives culminating in the 4-12-2 Union Pacific type, but Alfred Bruce writes that this was always regarded as a maintenance and a catastrophic failure concern?
As to trying every advanced steam idea Porta could think of, maybe the better to do this on a small locomotive than something road-enginer scale?
Switch engines are notorious for burning through a lot of coal on standby, but Porta thought that with enough cylinder insulation and with damper-controlled air to the firebox, he had this problem licked? I brought up Porta's claims on the thread about Genset Locomotives.
The peak steam demand was to be something like 11,000 lbs/hr. I had suggested that a diesel locomotive train-heat steam generator could do this in one of its larger sizes? If you wanted to go with light oil firing, such a think could be hooked up to a "fireless cooker" steam storage locomotive?
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