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Last, best chance for railroad steam locomotives

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Last, best chance for railroad steam locomotives
Posted by Paul Milenkovic on Monday, March 15, 2021 10:35 AM

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.

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?  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?

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?

If GM "killed the electric car", what am I doing standing next to an EV-1, a half a block from the WSOR tracks?
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Posted by Overmod on Monday, March 15, 2021 11:55 AM

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.

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Posted by Overmod on Monday, March 15, 2021 12:58 PM

Paul Milenkovic
Other nominations go to Wardale's Red Devil locomotive in South Africa...

A problem, reading between the lines, was that the design depended extensively on both a skilled and motivated cadre of engineering and shop personnel, who did NOT survive political changes.  A very similar thing happened with the QJ experiments --  apparently complicated by what turned out to be a colossal lack of sincerity about retaining even optimized working steam.  This was as I recall around the time the replica Hudson project was gearing up at Datong... only to be dropped with the 'stated' reasons being highly suspicious at best.

... the ACE 3000 project that never advanced beyond the Vu-Graph stage in the U.S. ...

Thereupon hangs a tale not fully told to this day; Mr. Wardale and Ross Rowland having decidedly different accounts of the project.  In my opinion far more detail design needed to be done even on the (grossly overcomplicated) locomotive in the patent description, starting with a frame that would work as intended.

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.

And in a world where presumably LDP could teach his philosophies to willing Hispanophone cohorts, and ready access to certain modern materials and the tools and equipment to work with them correctly, the trick might have been made to work.  For a while.  Perhaps I'm mistaken, but I don't see this being sustainable in Cuba, especially after the fall of the USSR.  And there are few things worse than a specialized and complex design in a cheapening world -- ask PRR about it, for example... Whistling

The 3-cylinder arrangement required a cranked axle, but may there is lower risk of this thing breaking in this lighter duty application?

It was my impression that the three cylinders were to give more even torque and less augment with very small wheels.  If the detail design were done right the 'additional' maintenance expense of the arrangement over 2 cylinders might not be so bad -- using the 'right' sort of cylinder tribology as well as steam distribution, for example.  

[/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?

There is something to be said for this, but it vaguely reminds me of the shop that did my Walker mowers -- they were involved in that classic 'Murican sport, competitive lawn-tractor racing, and were able to build a version of the three-cylinder Kubota in the Walkers that made over 750hp on the dynamometer.  This is a comparable technological tour de force as making a Third World agricultural locomotive Generation 2 or better... and about as sensible capital-wise, and arguably about as maintainable.  

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 would like to see this done properly with bagasse firing.  Perhaps it could be.   I'd not hold my breath for the big savings, though.  (And no, no chain-grate, either.)

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?

Have you actually looked at a locomotive train-heat steam generator, or consulted the manual for one?  There are few things more complicated than the rig the Golden Rock people ginned up for 'modern steam' firing -- but something like an OK4620 qualifies.  And that's before you start dealing with the effects of untreated water, recognizing that Porta Treatment won't work properly in them (let alone in a tapered monotube, if you were thinking of going there, which I really, really wouldn't...)

If you wanted to go with light oil firing, such a thing could be hooked up to a "fireless cooker" steam storage locomotive?

This of course is the 'first best use' of the bagasse firing: nake process steam in a stationary mill, and sparge it in as necessary.  Then if you want separately-fired superheat with catalytic ignition, or boost baseline endurance with a small on-board fire, you're much better set.

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?

Part of the issue I have with the design, and I don't claim by any means to be 'expert', is that everything I researched or learned about practical bagasse firing won't support that intermittent 'severe' model of operation.  You might get something to work on a duty cycle like the Teresa Cristina where there is sustained running with GPCS-style lean and reducing firing conditions and good Rankine-cycle recuperation of combustion-plume heat.  But that is most certainly not what my understanding of the LVM designs was likely to be used for.

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Posted by Paul Milenkovic on Monday, March 15, 2021 3:33 PM

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?
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Posted by Overmod on Monday, March 15, 2021 4:26 PM

Paul Milenkovic
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 eliminate the uncovered crown-sheet BLEVE explosion hazard of the staybolt firebox.

There were numerous attempts at 'steam generator' arrangements for power, not all of which were strict monotubes (let alone tapered once-through with superheat, as with Doble).  They can be nifty; you might get a kick out of the projected steam generator for the Cyclone  'supercritical pressure engine' which was, for a few shining minutes anyway, going to be the Lingenfelter Sledgehammer of steam LSR vehicles -- but as a cheap method for onboard charging of a typical fireless locomotive they leave some things to be desired.

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...

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Posted by Juniatha on Friday, March 19, 2021 7:37 PM

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

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Posted by Overmod on Friday, March 19, 2021 8:18 PM

Juniatha
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 and uproot it.

Let me be first, probably of many, to request 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 of it I made in 1992 at the age of sixteen - that in her final version, as a Mountain (by w/a) type with a European standard w/a 4-4 tender, at least doubled the overall efficiency of some better late hour classic steam designs that have been.

Since my first designs, at about the same age, were high-wheeled de Glehn compounds (albeit 4-8-4s), I'd be interested to see these, too. 

Or - on quite the other end I could retrieve the 0-6-0 with a six wheel tender, a plan to rebuild one of Meiningen's 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 did their same old standard procedures overhauls of existing preserved steam engines.

Have you contacted Andreas Schwander?  This is a key interest of his, and I think he has connections to promote it.

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Posted by Overmod on Friday, March 19, 2021 8:44 PM

Juniatha
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.

Note that this is just the opposite of the method used on the T1 to lessen main-rod stroke - a key difference (which was reported in detail when the T1 design was discussed in Atlantic City) was that the roller rods could be easily pressed on and off that design.  That could certainly not be said for Porta's 'design' -- I think about the best that could be expected would be a segmented bronze inner bushing made comparable to the inner lubricant-holding floating bushing in a UP FEF2 or 3, with an outer bronze or compatible eye pressed over the segments once on the pin, machined with suitable radius to allow lateral on the main as for roller-bearing rods.  This would also tolerate the very generous radii between machined pin faces that would be needed for the design to work.

In his defense, it does make sense to decrease the amount of necessary overbalance in a high-speed engine, and if you want (for some reason best known to a philosophical engineer like LDP) to do this with mains inside -- and there are good nominal reasons to have the mains inside the rods, as well as at shorter stroke than the coupling rods -- that design and perhaps no other would do it.  Personally I think the rod force to all the coupled wheels, outboard of not only a necked section but an offset one, would be suicidal in the long run -- before we take up the issue of making the pin seat and axle seat far enough apart that the wheel center does not crack under loading too (note that the pin location in the 72" center of the T1 main was chosen to be a safe minimum for this not to happen; this too being explicitly discussed).

If Porta ever discussed DNB carefully (and the resulting much greater issues that might pose with hot-short characteristics), I have not seen it.  A Cunningham circulator is supposed to deal with this somewhat in the water legs, but unless the transition to the crown or other structure (which is also partly determined by the desired combustion plume and gas flow inside the inner wrapper) is similarly improved you've likely set yourself up for problems.  I also don't remember LDP proposing an effective way to keep watertubes wholly unencrusted without periodic turbining, something his published tube layouts certainly didn't make easy or inexpensive (and which historically has been one of the great stated failure points of even something as simple as watertube fireboxes).  Meanwhile, while it was still the Porta-McMahon treatment, there were problems with the necessary antifoam additive at pressures (and saturation temperatures) even in the 200psi range, which I don't recall were satisfactorily addressed before the changed emphasis of the 5AT project.  Now there are ways to get around that part of the problem (for example by greatly increasing the vertical steam separation) but I am still a bit nervous about using PT at very high pressures (e.g. where even small amounts of silica become a dangerous contaminant).

Are you familiar with Porta's design of a non-sliding pin-jointed crosshead?  Professor Milenkovic, I think, would be fascinated by it ... in a number of senses.  

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Posted by Juniatha on Friday, March 19, 2021 11:46 PM

Overmod,

you can't get around boiler water temperature increasing with increasing steam pressure, there is no way any circulator can help you: it will and has to reach its due temp before it can start boiling. What you probably point to is overheating of fireside surfaces due to bad water circulation and thus steam cushioning on the waterside - sure that would likely cause overheating - similar to that caused by scaling. To me, taking care of proper water circulation is a thing not mentioned because it is sine qua non to design.

"Are you familiar with Porta's design of a non-sliding pin-jointed crosshead?"
No - I had once come up with my own lever system, mainly for slow power. However, an enclosed system where the slide bar goes around the crosshead instead of the old way with the crosshead surrounding the ruler and a good mechanical grease / solid lubrication or if we speak of up-to-date modern technology - a dry-running combination of materials (which then needs to be protected carefully against intrusion of dust and particles) with a slide bar and crosshead is still the best and potentially lightest solution. Such horrible amounts of wear and play as were tolerated in US steam are of course absolutely unacceptable and I wonder if that didn't break a piston rod now and then. At least it led to a quick demise of the rear stuffing box.

Asymmetrically turned pin with different strokes coupling / main rods:
I don't think it is worth dropping any more word about that nonsense and the weird forces it creates in the part, the only proper way to have a main pin is the regular symmetrical form, no doubt about it. Btw piston travel of the T1 was very nearly the same as standard with DR types of engines and they had the regular form of pins, i.e. same stroke for both coupling and main rods - there never was a problem with wheel centers cracking between pin and axle - and those wheels were comparatively very delicate in design. Many even 'survived' one or more water blows. For instance, I know that the Berlin group around their 52 8170 managed to fabricate a water blow when shunting at the yard around their shed at Schöneweide - the cylinder cover was pushed so that there was a huge steam escape from then on - yet the wheel was undisturbed. Full piston force at 228 psi b p is 45 tons (metric) - quite a thrust for an engine of less than 1/2 the axle-load of US mainline power, piston diameter is larger than that of NYC J-3a Hudsons!

" it does make sense to decrease the amount of necessary overbalance in a high-speed engine"
If you had been on the footplate of a German two-cylinder engine - which all did have that 'decreased overbalance' (but due to limiting the amount of hammer blow to 10% of static axle load) you would be much more cautious about this.
I can only tell you the effect of the free mass forces set loose by this is disastrous to engine conditions. I have met so many engines that were worn down to the limit by this and were shaky in everything you could think of and then some! Some were nothing but an offense to the crew to drive at regular speed. True, to this usually came irregularities in valve gear working, in cylinder clearance and in axle bearings having developed play and - last not least - differences in wheel and rod spacings - one millimeter can cause hard riding if the bearings have not worn to tolerate it! Former work tolerances after an overhaul were 1/10 *) between two axles and 3/10 over all coupled axles - this was later given up to the end of steam traction which caused increasingly hard riding of virtually all locomotives - even the newly overhauled were little better. You can see that on the video I posted of the Swiss 01 202 of her trip from Stuttgart in my former posting.

On the other hand, I remember 52 8117 - then one of a few still on the roster of DR - at the head of a semi-fast regular train going north towards Berlin: she sure was rattling, you could see that from the car window, but she ran dead straight ahead - no nosing, no swaying, no nothing, just straight ahead, smoke wings vibrating, at somewhat above regular service speed limit, ~ 60 mph all the way, the train was light for her and there was no exhaust noise (the driver later said he used some below 30 % c/o and 6 bar (85 psi) at steam chest - close to the minimum (70 psi) you had to maintain to prevent clattering of the Trovimov piston-valves). There was just that hammering of the reciprocating mass at the bumpers of the first car (coupling was not tight enough, trainman who did the coupling had made it easy on himself). Yet when we arrived in Berlin-Zoo there was no hot bearing, not the slightest hint, the fire was fine on the grate and steam was plenty: safety valves soon cracked open at the stop.
That was my farewell to the 52-80 in Berlin in 1993 - a type of engine that never gave up and was thankful for but a handful of taking care!
Well, ok - excuse my digress ...

Juniatha

 * one tenths / three tenths of a millimeter!

 

Oh, btw: "Have you contacted Andreas Schwander?  This is a key interest of his, and I think he has connections to promote it."

No - how should I? Don't have the address, have no contact long since with the German steam preserve scene - and the opportunity is also gone long since: all remaining fireless 0-6-0s have been scrapped; same with wheel sets and auxilliaries including complete stoker machinery, there was a serious practical proposal to use the 1850 mm (73") wheel sets of a Pt47 and a 44 class crank axle to build a new 32 class Prairie three-cylinder engine with stoker firing on a 17 sqft wide grate of a new 290 psi boiler, combined with an ex 52 semi-cylindrical tender, one of the rare long form with 5900 mm (232") wheel base had been fixed at the ZNTK Gniezno. All gone - all scrapped!  Well, I was just observing - only once I got more directly involved: when I saw at Wolsztyn one ex 42 in dull but at closer examination not too bad condition on the 'forlorn track'. I got to whirl up some PKP guys at headquarters about that engine, seriously attempting to bring her into the engine house and finally have her (I should say: him, because to me the 42 is 'the bad brother of the 52') overhauled. It were my parents who when they got wind of it made it clear to me I was about to chain a 150 tons chunk of steel to my feet and make myself depending on the more or less good will of a lot of people I don't even know. And even if I should succeed in making him servicable again - where would I go? to Schöneweide? Well, quite certainly not!!  Vienna? the ÖBB / traffic museum, the ÖGEG, too, all had their own 42. The US even? Those costs of transport - prohibiting! And all that only to have endless trouble with US laws and norms and demands ...  No - I slowly and sadly woke up ...

 

 4:46h ?? It is 23:00h over here!

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Posted by Paul Milenkovic on Saturday, March 20, 2021 12:22 PM

I guess I am being "tag-teamed" with criticism of Porta's ideas as being outlandish.

The man did apprentice under Chapelon?  He uprated and upgraded the 2-foot gauge Japanese-built 2-10-2's for heavy coal haulage in Patagonia, Argentina?  He rebuilt a metre-gauge locomotive into his compound-expansion "Argentina"?  He applied steam-powered rams for underfeed stoking, a version of the Gas Producer Combustion System (GPSC) and one of his improved exhausts to the Hunslet Austerity-class tank switch engine in England?

So by bringing up the Cuban Prometheus project, I am defending Porta as being all-knowing and all-wise in what further steam locomotive development could have accomplished?

To take the points raised, I am skeptical of Porta's claim of going to 1000 PSI boiler pressure with a staybolt firebox, or of even going to that steam pressure with a watertube boiler.  The American Society of Mechanical Engineer (ASME) got its start in developing codes for boiler safety, and they recently published an account of an accident where contemporaneous with the Gulf War, the engine-room crew of the helicopter assault ship Iwo Jima perished from a steam release from a burst fitting in a 600-PSI steam circuit.  The fatal accident was attributed to a contractor during a port call for repairs "in that part of the world" cutting corners in replacing the fitting with a substandard part or with the wrong bolts.

Someone can tell me the pressure level that poses the danger that an invisible high-pressure steam leak can cut a crew member in half.  The accident with the Fury locomotive using the high-pressure split-circuit Schmidt system in England along with the Iwo Jima accident suggests that pressures not much above 300 PSI are an accident waiting to happen in a mobile boiler subject to the railroad shock and vibration environment.  I am also thinking of the scary but non-fatal incident of a burst circulator tube in "A Niagara Falls" in Steam Glory 3 as reason to stay away from pressures much beyond 300 PSI.

I believe Porta that he studied the German TUV codes and that a staybolt boiler could be designed for, what did the Cuban locomotive call for, 368 PSI, but maybe the project could have backed off from that increase in boiler pressure?

Moving down the list, there is the 3-cylinder compound expansion and putting a pair of LP cylinders outboard?  Isn't that the arrangement on the 242-A1?  Besides, Porta's idea was for a light-duty industrial/branchline locomotive with less cylinder volume?

As to the problems of overexpansion and cylinder compression and all of that, the idea of compound expansion is that if you expand to, say, 40% in both HP and LP, that level of expansion combined with torque smoothing from the 3-cylinder arrangement could, in principle, allow close to max tractive effort.  40% is no big deal as a cutoff with conventional valve gear, but in compound mode, that could get you to an effective 16% expansion giving high efficiency.  Reducing the cutoff in both HP and LP to 25% would have you overexpanded? 

I think what June is trying to say that if the compound cylinders were sized and the full-tractive-effort cutoff balanced for 40%, reducing the cutoff may require such a small level of cutoff in one of the cylinder banks that it would be unworkable with conventional valve gear without running into severe compression/rod knock?

Wardale said he was impressed on how one of his locomotive drivers took to full-throttle working, that not only did they guy "steam the locomotive" flat-out, he also "drifted flat out."  Actually, alternating between full-throttle and "drifting" is a tactic for "hypermiling" in a gas-engine automobile, which is an automotive sport among the ecologically inclined car enthusiast, and this works especially well with hybrid or other cars that switch off the injectors during coasting.  I have ridden on city buses that appear to be driven that way.  It might be more reasonable to alternate between full (or a large fraction of tractive effort) when steaming and then drifting where the greater mass of a locomotive and train cars stores kinetic energy with less change in speed.


And yes, even his acolyte Wardale was complaining about how hard it was to get the GPCS to work consistently, and Wardales luck in South Africa with a version of Porta Water Treatment consistently led to foaming and carryover that was ruining the superheater header from flash-boiling "bumping" knocks.  And yes, Wardale saying "go with pulverized-coal firing" is probably non-starter, probably from "slagging" of the front tube sheet even if you could solve the problem of a coal-powder explosion by grinding the powder at the point of firebox injections?

On bagasse firing, Porta was said to have been working on that one, even to the point of stoking small black-power firecrackers on the firebed to mitigate the "caking" tendency of that fuel?

Seriously, if some enthusiast group with environmental leanings (cough, the Coalition for Sustainable rail wanting to break Mallard's speed record with a Wardale-ized AT&SF 4-6-4) were to concentrate on a Modern Steam project, perhaps a smaller-than-US-mainline passenger or freight locomotive such as the Prometheus locomotive might be a better focus?

 

If GM "killed the electric car", what am I doing standing next to an EV-1, a half a block from the WSOR tracks?
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Posted by Paul Milenkovic on Saturday, March 20, 2021 12:34 PM

Finally, for Professor Thinks-the-Baker-Gear-is-the-Coolest-Thing to have failed to have thought about what Porta's non-sliding crosshead could be been, such a thing has not happened. 

The ACE 3000 specified "pendulum links" for the piston-valve valve gear, where a pendulum link gives a crude approximation to straight line.  A much better approximation is the Watt's link (sometimes given as Watts link) used for guiding the rear axle up and down for the Police Interceptor version of the Ford Crown Victoria full-sized V-8 engined rear-drive car.  It is also used by Talgo in its axle-guiding linkage.  Steam engine inventor James Watt thought the approximation good enough to use with a beam-motion stationary steam engine, and people in the "live steam models" community have built them that way.

There is a complicated 7-bar linkage due to Peaucellier giving exact straight-line motion, but there is a simpler exact linkage due to Sarrus that is easy to build.  The problem with the Sarrus linkage is that it has links sticking out of the plane, and it might pose clearance problems for use as a replacement for the crosshead guide. 

Looking at the Wikipedia article Peaucellier–Lipkin linkage - Wikipedia, Lipkin is now credited?  Professor Harvey Lipkin at Georgia tech is someone whose mechanism work I greatly admire, but someone stuck his name on this thing?  Sorry, a different Lipkin contemporaneous with Peaucellier.

Wikipedia has good animation of the Sarrus Sarrus linkage - Wikipedia, and you can see where it could have clearance problems on a locomotive.  I have built models of this Sarrus out of creased foam-core board.  One could reduce the problem of its "elbow spread" by using a narrower angle between elbows than 90-deg, but then you reduce its stiffness.

If GM "killed the electric car", what am I doing standing next to an EV-1, a half a block from the WSOR tracks?
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Posted by Erik_Mag on Saturday, March 20, 2021 1:54 PM

Paul Milenkovic

Wardale said he was impressed on how one of his locomotive drivers took to full-throttle working, that not only did they guy "steam the locomotive" flat-out, he also "drifted flat out."  Actually, alternating between full-throttle and "drifting" is a tactic for "hypermiling" in a gas-engine automobile, which is an automotive sport among the ecologically inclined car enthusiast, and this works especially well with hybrid or other cars that switch off the injectors during coasting.  I have ridden on city buses that appear to be driven that way.  It might be more reasonable to alternate between full (or a large fraction of tractive effort) when steaming and then drifting where the greater mass of a locomotive and train cars stores kinetic energy with less change in speed.

Old streetcars were operated that way to spend minimal time in resistance notches. Gasolene autos would get more of a benefit from full throttle and coasting than a diesel auto due to pumping losses past the throttle. I recall seeing a plot of mpg vs speed for a MBZ 240 compared to a MBZ 240D. The mpg for the 240D peaked at 15 mph with a value maybe twice that of the 240, where both cars were presumably being driven at constant speed.

I was under the impression that steam locomotives were most efficient at substantially less than maximum output, possibly more due to less unburned fuel being sent up the stack and more time for the combustion products to reside in the combustion chamber.

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Posted by Sara T on Saturday, March 20, 2021 3:44 PM

>>That was my farewell to the 52-80 in Berlin in 1993 - a type of engine that never gave up and was thankful for but a handful of taking care!<<

I feel with you. You had told me about it. I know it was hard, but still I keep telling you: don't be sad it has ended, be happy you have experienced it!

The 42: Yes, I see, (s)he is much more rare than the 52, but doesn't look as well balanced with the thick boiler, (s)he looks shorter, too (is not really).

Hha! "bad brother of the 52" Smile

That was before we got to know each other - I could have told you: you had a 30 - 40 % chance of succeeding, but looking at the severs consequences if you didn't it was fully right to abandon the project; you would have had a person with some power at the head quarters in Warszawa, but the people at Wolsztyn would have given you a hell of resistance against that loco leaving the depot. Irony: I feel the loco still exists and is externally made up. Could somebody from this forum know of it and tell?

 

the forum reads  9:44 - here it is 9:52: looks like it gives European time with my postings?

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Posted by Overmod on Saturday, March 20, 2021 5:26 PM

Paul Milenkovic
I guess I am being "tag-teamed" with criticism of Porta's ideas as being outlandish.

Not at all -- although it might seem that way, circumstantially.  What we're objecting to are certain places in his work where his ingenuity and passion led to details that might be difficult, or uneconomical, to implement in practice.

LDP was a friend, admittedly early in my life and late in his, and I do cherish his memory and respect the things he knew and loved about steam power.  On the other hand, sometimes he seemed to assume certain things that differed from either my understanding or my opinion, and it is about these that I'm commenting.  I don't mean to imply "I'm right and he was wrong" instead of considering the underlying issues for what they are.

The man did apprentice under Chapelon?  He uprated and upgraded the 2-foot gauge Japanese-built 2-10-2's for heavy coal haulage in Patagonia, Argentina?  He rebuilt a metre-gauge locomotive into his compound-expansion "Argentina"?  He applied steam-powered rams for underfeed stoking, a version of the Gas Producer Combustion System (GPSC) and one of his improved exhausts to the Hunslet Austerity-class tank switch engine in England?{/quote]All that is so, and you should not leave out the Lempor as an ongoing example of what he was trying to achieve.  None of that implies either that everything he innovated was supportable, or that everything he tried was necessarily a success.

So by bringing up the Cuban Prometheus project, I am defending Porta as being all-knowing and all-wise in what further steam locomotive development could have accomplished?

There are those who so believe.  I deeply wish that someone would put his proposals for 'improving' the Tornado replica in detail, because they're fascinating.  To this day Ross Rowland considers him to have been one of the most, if not foremost authorities on steam; he says he dismissed Mr. Wardale from the ACE program because there could only be one authority on development and Mr. Porta was it.

To take the points raised, I am skeptical of Porta's claim of going to 1000 PSI boiler pressure with a staybolt firebox, or of even going to that steam pressure with a watertube boiler.  The American Society of Mechanical Engineer (ASME) got its start in developing codes for boiler safety...

And now do again; with the assistance of the National Board ESC they now provide a code for Locomotive Boilers again, a topic to which I'll return in a moment; the working factor of safety is now 5 in FRA part 230 (and yes, this has complicated the return of 1361 to steam even at 205psi...)

...and they recently published an account of an accident where contemporaneous with the Gulf War, the engine-room crew of the helicopter assault ship Iwo Jima perished from a steam release from a burst fitting in a 600-PSI steam circuit.  The fatal accident was attributed to a contractor during a port call for repairs "in that part of the world" cutting corners in replacing the fitting with a substandard part or with the wrong bolts.

My concern with high pressure is only peripherally concerned with substandard repair, although I did mention it explicitly and somewhat sardonically in my initial reply (as there are documented catastrophic sheet failures due to (nearly-incredible!) field welding and seal-welding practice even at typical 'mill engine' pressure, probably at most well under 200psi.  I'll return to that, too, in a moment.

Someone can tell me the pressure level that poses the danger that an invisible high-pressure steam leak can cut a crew member in half.

I have only seen this in conjunction with submarine pressure-hull accidents, and a fictional account of one such led to my introduction to waterjet cutting tools (which were as I recall at the time an Italian specialty).  In my opinion the likelihood of such a pinhole-nozzle leak on a locomotive that does not rapidly progress to a much larger "orifice" is relatively small, and unlikely to occur on a welded backhead or any other location where people might be 'adjacent to', that has been properly NDT-tested.

Frankly I don't foresee the day that men, even in good modern nanoinsulated or armored suits, go into hot fireboxes as NYC had them do to take care of leaks at some high percentage of working pressure.  That's the only other place I see a problem with mechanical damage.

In any case, that isn't one of the real reasons not to use high pressure on a locomotive.  You are welcome to sit in on one of the Code Week meetings that feature the Locomotive Boilers I sections (they are not conducted every Code Week, but you can have the agendas e-mailed to you) and discuss th

The accident with the Fury locomotive using the high-pressure split-circuit Schmidt system in England along with the Iwo Jima accident suggests that pressures not much above 300 PSI are an accident waiting to happen in a mobile boiler subject to the railroad shock and vibration environment.

The Fury failure is less of a motion cautionary tale as in having high-pressure elements exposed directly to a firebox volume which can communicate with the cab through either an open firedoor or secondary-air orifices.  What killed the Superheater Company's man was superheated flame, not superheated steam.  I believe there was a very similar accident to a French Mountain a few years ago that Juniatha discussed; there are pictures of the failed elements both there and in the case of Fury that are very enlightening concerning the force involved, but they notably did not progress to catastrophic release. 
I am also thinking of the scary but non-fatal incident of a burst circulator tube in "A Niagara Falls" in Steam Glory 3 as reason to stay away from pressures much beyond 300 PSI.

I believe Porta that he studied the German TUV codes and that a staybolt boiler could be designed for, what did the Cuban locomotive call for, 368 PSI, but maybe the project could have backed off from that increase in boiler pressure?

Perhaps, but the compound expansion benefits from higher pressure, and a 25atm boiler is not out of the practical range... thermodynamically.  Much more of a question is how you maintain that pressure in the field, even with "too-cheap-to-meter" biomasa as the fuel.

One of Porta's stated reasons for higher pressure is reducing the water rate, which is a significant issue on a locomotive operating away from sources of clean water (at least, clean enough to be made serviceable in a 25atm boiler) with a minimum either of chemicals or knowhow and discipline to dose them.   

Moving down the list, there is the 3-cylinder compound expansion and putting a pair of LP cylinders outboard?  Isn't that the arrangement on the 242-A1?

Yes, and on the Baldwin 60000 and other practical Smith compounds as well.  This arrangement was one of the more 'proven' arrangements for compounds, with the center cylinder HP and the two outside LP totalling to near the desired expansion ratio. 

Besides, Porta's idea was for a light-duty industrial/branchline locomotive with less cylinder volume?[/quote]But less volume does not imply fewer cylinders, or light duty implying that compounding could be dispensed with for operating economy (as distinct from first cost or maintenance issues).  On the contrary, there are advantages for multiple cylinders, including divided thrust and better balance, that apply to small-wheeled ag power operating on cheaply-built and light track.  Sentinel in the 1930s marketed motor locomotives for this same 'niche', some of which as I recall used pressures higher than 25atm.

As to the problems of overexpansion and cylinder compression and all of that, the idea of compound expansion is that if you expand to, say, 40% in both HP and LP, that level of expansion combined with torque smoothing from the 3-cylinder arrangement could, in principle, allow close to max tractive effort.  40% is no big deal as a cutoff with conventional valve gear, but in compound mode, that could get you to an effective 16% expansion giving high efficiency.  Reducing the cutoff in both HP and LP to 25% would have you overexpanded?

First, why would you want the cutoff in the HP to be the same as the LP, even for simplicity?  In my opinion a fundamental assumption is that the HP cutoff will be different, probably in both timing and duration, from the LP; this is one of the principal reasons for IP injection to help smooth out the torque. 

Wardale said he was impressed on how one of his locomotive drivers took to full-throttle working, that not only did they guy "steam the locomotive" flat-out, he also "drifted flat out."  Actually, alternating between full-throttle and "drifting" is a tactic for "hypermiling" in a gas-engine automobile, which is an automotive sport among the ecologically inclined car enthusiast, and this works especially well with hybrid or other cars that switch off the injectors during coasting.

No hypermiler does the 'coasting' without putting the transmission or equivalent in neutral and shutting the engine off entirely.  That is not possible on a regular reciprocating steam locomotive, and in any case analogies to IC engine braking do not particularly hold.  We have had discussions on drifting practice here in the past; you might want to find and re-read them.  My own preference is to keep 'displacement steam' admitted to the cylinder to displace any air, even in the presence of bypass valves, but there are arguments otherwise, and a number of compression brake arrangements as well.

Hypermiling acceleration, likewise, is done keeping the engine close to the effective peak of the torque curve, but this implies a transmission that can do the appropriate speed matching not to 'waste' any of that power especially at low road speed.  Simple rods do this relatively poorly.  

It might be more reasonable to alternate between full (or a large fraction of tractive effort) when steaming and then drifting where the greater mass of a locomotive and train cars stores kinetic energy with less change in speed.

This prospect on an agricultural railway fills me with a certain amount of dread, particularly since tightlock couplers and good draft gear are likely not in oversupply there.  Far better to do as Porta planned on the Dona Cristina: set for consistent drawbar pull to balance train resistance at lowest water rate; the track profile, winds, etc. there allowed this to remain common for long periods of time (and hence the chemistry experiment that is GPCS firing could likewise be maintained in reasonable equilibrium for a comparable time...)

[quote ...And yes, Wardale saying "go with pulverized-coal firing" is probably non-starter, probably from "slagging" of the front tube sheet even if you could solve the problem of a coal-powder explosion by grinding the powder at the point of firebox injections?[/quote]Slagging of the front tubesheet?  By then your fly ash is not only solid but probably starting to be triturated...

On bagasse firing, Porta was said to have been working on that one, even to the point of stoking small black-power firecrackers on the firebed to mitigate the "caking" tendency of that fuel?

I can put you in touch with the sources who did actual bagasse firing, and you can read something about stationary practice in the B&W 'Steam: Its Generation and Use' industrial sections.  There are all sorts of cockamamie expedients, including the aforementioned underfeed stoking with tuyere flow to remove as much of the water as possible before combustion.  All this and GPCS too... conveniently ignoring the issue of luminous flame vs. peaky thermal emission from transparent gas combustion... isn't something I expect to be made reasonably cost-effective in a Cuban sugar-cane field.  Do I need to say more?

Seriously, if some enthusiast group with environmental leanings (cough, the Coalition for Sustainable rail wanting to break Mallard's speed record with a Wardale-ized AT&SF 4-6-4) were to concentrate on a Modern Steam project, perhaps a smaller-than-US-mainline passenger or freight locomotive such as the Prometheus locomotive might be a better focus?

This has been argued; in fact Davidson Ward has indicated that the torrefied-fuel project applicability would be much more to smaller power -- Project 130 is only a big publicity stunt to draw attention to the promise of the technology.  (What is perhaps amusing is that a very great amount of industrial engineering went into torrefaction by the early 2000s, no small amount of it as a 'clean coal' co-firing material, and there is little 'experimental' work that could be done in Minneapolis either to add to patentable knowledge or to make the locomotive eminently practical to run at high speed.

The problem is that steam still requires regular attention and maintenance, and she behaves poorly when she doesn't get it, usually in many ways.  That is my fundamental objection to building a highly complicated machine in relatively small numbers, requiring substantial training and discipline to 'care and feed'.  We have already reached the stage where either a modern 'fireless' locomotive or a good battery locomotive could be used in conjunction with a modern bagasse-fired steam plant, with the standby efficiency and fire risk largely handled, and with no sensitive fired-pressure-vessel risks.  Since such a plant is required to do anything with the sugar cane, much of the additional capital involved for the large plant and infrastructure is going to be paid for

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Posted by Overmod on Saturday, March 20, 2021 6:05 PM

Juniatha
you can't get around boiler water temperature increasing with increasing steam pressure, there is no way any circulator can help you: it will and has to reach its due temp before it can start boiling. What you probably point to is overheating of fireside surfaces due to bad water circulation and thus steam cushioning on the waterside - sure that would likely cause overheating - similar to that caused by scaling.

Actually DNB (as I use the term) can be a consequence of excessive heat flux even through clean plate to water at saturation pressure; I confess I hadn't thought of 'hot short' issues in inner-wrapper plate even at relatively high nominal saturation temperature, just at the overheat temperatures reached in 'bad' circulation. 

The 'enhanced circulation' as with Lamont boilers is to increase the water flow across the affected regions, to mechanically displace the extended boiling before Eisenhoffer/Leidenfrost effect can develop beyond the ability of saturation pressure to overcome it.  The temperature of gas at the waterside does not change dramatically, but the nucleation to steam (or potential for departure from nucleate boiling in regions of highest, possibly transient heat flux) does, and of course the plate heating in those regions would increase (against what is now a reasonably-good insulating steam film, as in superheaters).

In a Lamont waterwall, the feedwater circulation is continuous at about 6x times peak steam demand, and 100% of the fireside waterwall is continuously swept at that speed, with the full steam generation carried mechanically through the space and no separation performed vertically into a 'steam space' until centrifugal separation.  For Cunningham circulation (which takes downcoming water from the convection section and pipes it under jet-pump pressure to a manifold and nozzles spaced near the bottom of the water legs in a staybolted box) there is no 'special accommodation' for the accelerated circulation of 'pachinko' nucleate bubbles up the water legs once they get to the 'top' across the relatively unconstrained space above the crown.  While in tests this notably affected the boiler's ability to take up heat from the combustion plume, it still leaves firing constrained by concerns over the crownsheet and its circulation.  So it is practically difficult to enhance firing (or combustion heat transfer) to the walls without increasing exposure of at least some of the crown sheet to higher heat as well. but with lower defined circulation. 

 

I agree with you that using suitably-hardened surfaces in a multiple-bearing crosshead combined with modern tribology is a 'right' solution compared to theoretically-low-friction pin-jointed anything.  It is interesting to contemplate things that would shield that area from dust and moisture.

The method I devised to protect piston rods (and the rear gland) from contamination was to use a variant of a long-travel off-road shock boot between the rear of the cylinder block and the crosshead behind the piston-rod key.  This can be vented to handle any blow, and easily removed and replaced for inspection; any severe shock would be accommodated by the elastomer and any internal contact with the rod surface insufficient to damage or distort it.

 

Easiest way to reach Andreas is probably via LinkedIn, if you 'do' that.  PM me for the e-mail address I have.

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Posted by Overmod on Saturday, March 20, 2021 6:15 PM

Paul Milenkovic
There is a complicated 7-bar linkage due to Peaucellier giving exact straight-line motion, but there is a simpler exact linkage due to Sarrus that is easy to build.  The problem with the Sarrus linkage is that it has links sticking out of the plane, and it might pose clearance problems for use as a replacement for the crosshead guide. 

The linkage I saw was something worked out, interestingly enough, by comparison to pin-jointing conventional valve gear linkage with either roller or needle bearings to simplify maintenance and long service life; we had discussions on how this might be used with AAR M-942 grease lubrication for life in excess of that of regularly-dressed driver tires.

The problem was that, in the version I saw, this presumed that the pin joints were adequate to 'take' any transverse component of thrust or reaction.  I was not, and am not, convinced that this could be made to deflect or buckle sideways under not-uncommon conditions, certainly to the point you'd start to see Vauclain Compound-like distortion and blow at the piston-rod glands.

Something you might do with a Sarrus linkage is use a pantograph arrangement rather than simple hinging: this adds to the number of pin joints but reduces the necessary horizontal excursion.  Whether this is in fact 'better' than good tribology on a suitably hard-faced multiple-bearing crosshead is... open to argument.

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Posted by Juniatha on Monday, March 22, 2021 4:03 AM

Overmod

Mind that I wrote

'or'

not 'and'

so decide which one ...

or, no: actually I think we better leave it as it is, for me it would only mean having to make up a text explaining details and I have to find and scan the drawing(s), so it would mean hours of work to put it up (and I don't have so much spare time today) and then it would only create trouble, me having to explain, defend, explain ... and so on, it would only mean hassle and bla-bla.

Naw, ok, let's leave it as it is - nobody hurt, me not either, everything's fine and we are all happy. Maybe some other time. Steam is gone anyways.

Never mind, have a nice day, today

Greetings

=J=

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Posted by CSSHEGEWISCH on Monday, March 22, 2021 10:06 AM

Just an observation from a diesel enthusiast.  After reading these various posts, it appears to me that most of the proposed designs discussed entail an increasing degree of complexity that might improve operating efficiency but would require additional maintenance expense on what was already a maintenance-intensive machine.

The daily commute is part of everyday life but I get two rides a day out of it. Paul
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Posted by Overmod on Monday, March 22, 2021 2:30 PM

CSSHEGEWISCH
After reading these various posts, it appears to me that most of the proposed designs discussed entail an increasing degree of complexity that might improve operating efficiency but would require additional maintenance expense on what was already a maintenance-intensive machine.

Part of Porta's emphasis, ironically, was on making the machine easier to maintain or better in the service for which it was intended.  There are examples in late steam practice -- the extended use of direct-steaming enginehouse systems; lubritoria; complicated turbine-driven systems to reduce parasitic losses; hot suits with controlled air to go into fireboxes; and very complicated lubrication systems, at the end verging on pressure lubrication, for example.  The idea of the cast engine bed as a specialty is a tremendous expense, likely not possible today; its function, though, in reducing maintenance expenses should be preserved (and that is why modern practice calls for a combination of lost-foam castings and carefully-cut and stamped pressings via an appropriate combination of welding techniques).

There is a somewhat lamentable tendency to overemphasize the importance of efficient Rankine-cycle thermodynamics.  Interestingly, it's the powerplant engineers with their Byzantine penny-pinching heat balance arrangements that were among the first to affirm the importance of high running reliability over parsimonious fuel and water consumption -- and putting the complications and higher materials and system costs where it most mattered to the real bottom line: producing ton-miles without surprise.

Of course, optimization "today" involves a completely different set of criteria.  Even looking at the 5AT effort vs. the LVM800 series will give you a constellation of different priorities (whether or not you agree that all the steps taken in either are 'right' from a North American perspective).  A very wide range of careful alternatives were developed for the replica T1 5550, not all of which were judged 'worth the candle' to provide for the organization's announced purposes.  


And it is for the organization with 'the gold to make the rules' to decide on what degree of complexity in the name of either thermodynamic or operating efficiencies are justifiable.  My concern with the LVM is that Porta presumed that the Cuban system could produce both the necessary support and training and the necessary motivation and pride to support the complexities.  In my opinion any practical chance of that closed with the collapse of the USSR, although few things would make me happier than to see Cuba take the necessary steps toward making it so.

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Posted by Flintlock76 on Monday, March 22, 2021 4:10 PM

Overmod
My concern with the LVM is that Porta presumed that the Cuban system could produce both the necessary support and training and the necessary motivation and pride to support the complexities. 

Maestro  Porta may have been presuming a little too much.  Steam-hunter Colin Garrett said the problem with Cuban steam maintanance was it ranged from outstanding to bombs looking for places to explode. He did see (and photographed) the remains of one of the latter, and this wasn't a crown sheet failure, this was the front course of the boiler disintegrating.  The engineer was oiling all around at the time, they only found his legs. 

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Posted by Sara T on Monday, March 22, 2021 4:28 PM

Oh, Juni!

Don't throw away an opportunity to put at least a little bit of light on your work!

Come on, you can do at least one. (I will talk to her!)

Guys, say, what do you think? 

                                                   0S5A0R0A3

 

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Posted by Overmod on Monday, March 22, 2021 6:03 PM

Sara T
Guys, say, what do you think? 

Well, you know what I'd say.  And to either or both ... her choice ... whenever she has the time.  (And I promise to keep digits-off, too...)

So moved.  Do I hear a second?

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Posted by Overmod on Monday, March 22, 2021 6:10 PM

Flintlock76
 
Overmod
My concern with the LVM is that Porta presumed that the Cuban system could produce both the necessary support and training and the necessary motivation and pride to support the complexities. 

This being precisely the thing that would have to change, and massively, and with both technical knowledge and equipment/material support, in order for any modern steam to thrive there.
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Posted by Flintlock76 on Monday, March 22, 2021 9:17 PM

Well, God rest his noble soul!

Maestro  Porta didn't see "left," and he didn't see "right," he only saw steam and the best ways to keep it alive, no matter who used it.  One has to admire him for that.

A steam locomotive's like a big friendly dog, it's apolitical.   

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Posted by Erik_Mag on Monday, March 22, 2021 9:55 PM

Overmod

The idea of the cast engine bed as a specialty is a tremendous expense, likely not possible today; its function, though, in reducing maintenance expenses should be preserved (and that is why modern practice calls for a combination of lost-foam castings and carefully-cut and stamped pressings via an appropriate combination of welding techniques).

The rudder bearing support for CVN's is on the order of a 400 ton casting, so casting an engine bed may not be completely out of the question... Pricing may be a bit on the high side.Whistling

On the other hand, maybe we can wait till someone makes a big enough 3D printer. Second best thing would be using 3D printed sand molds, though based on the one example of the 3D printed sand molds, a set for the T1 engine bed would be on the order of $10 million.

There is a somewhat lamentable tendency to overemphasize the importance of efficient Rankine-cycle thermodynamics.  Interestingly, it's the powerplant engineers with their Byzantine penny-pinching heat balance arrangements that were among the first to affirm the importance of high running reliability over parsimonious fuel and water consumption -- and putting the complications and higher materials and system costs where it most mattered to the real bottom line: producing ton-miles without surprise.

Mercury topping cycles come to mind, along with the D&H 1400-1403 series of experimentals. On a more recent note, the Ft St Vrain HTGR was built with steam turbine driven helium circulators to give a fraction of a per cent better thermal efficiency. The problem was that shaft seals on the turbine end were leaking a bit of steam into the helium side and that steam was not a particularly nice thing to have in intimate contact with the very hot graphite moderator.

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Posted by Juniatha on Monday, March 22, 2021 10:07 PM

Sara,

Ok - but I would need at least three members to request a posting to do it.

I think that's fair in view of the effort it takes to put it up.

And I choose which one.

=J=

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Posted by Juniatha on Monday, March 22, 2021 10:24 PM

Eric wrote: "On the other hand, maybe we can wait till someone makes a big enough 3D printer. Second best thing would be using 3D printed sand molds, though based on the one example of the 3D printed sand molds, a set for the T1 engine bed would be on the order of $10 million."

I had told the T1 5500 society years ago that there is a less costly method for building a one-off piece of frame: steel plates cutting, braces, guide stays, etc and welding it all into one piece. In tendency it will be lighter, yet it has to be normalized in the end and also it does not have fully the same quality of keeping to design measures as the old one-piece molding, yet it can be designed to fit the demand. But I got the impression it didn't find open ears, so to say. Neither my promoting fully welded construction for the boiler ...

Ok ...

=J=

 3:24 ? what time is that?

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Posted by SD70Dude on Tuesday, March 23, 2021 4:32 AM

I'd like to hear about your work.

As for the T1 project's frame and boiler, here's a discussion over on RYPN from a couple years ago about that very subject, with a post from their general manager explaining why they did not choose a cast frame:

http://www.rypn.org/forums/viewtopic.php?f=1&t=43986&start=30

jasonjohnson

We have already contacted 2 different foundries and sent them drawings of our frame to cast complete. One came back as a no bid and the other one wanted a minimum of 3 pours to get it right. The patterns and 3 pours would cost us $2.5 million. The company was more than capable, but felt it would take at least 2 pours to get all the gating right.

From above "if mass producing today they would cast frames" the truth is this is a one off. As Kelly showed, the PRR fabricated cylinders many times and even converted a K4 to poppet valves with welded cylinders. We have copies of those drawings and our engineers as using them to convert frame to weldments and some smaller more manageable castings.

This is the path we are headed down after boiler is mostly complete (minus tubes/flues)

We will be releasing frame drawings once we have completed conversion and finite stress analyses. Look for more details on this at the PRRT&HS convention in May.

Greetings from Alberta

-an Articulate Malcontent

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Posted by Erik_Mag on Tuesday, March 23, 2021 10:34 PM

J,

I was being a bit facetious with the 3D printer comment.

As for the materials aspect, I've told my son that there should be a big future in working on materials for 3D printing with his search for grad school. Strangely enough, stainless steel can actually perform better being 3D printed due to the rapid quenching.

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Posted by Overmod on Wednesday, March 24, 2021 8:51 AM

Erik_Mag
Strangely enough, stainless steel can actually perform better being 3D printed due to the rapid quenching.

A large part of this used to be because the process was a braze rather than sintering.  Very effective structures can be fabricated from that, including prototype rocket-engine components (remember the NASA contest?)  I had a certain disdain for brazing, as being kind of the poor relation of proper fusion welding, until I started learning stainless and titanium airframe construction.  Opened my eyes!

With the advent of cheap fiber lasers (how quickly disks seem to have become obsolescent!) practical joining of 5" or thicker sections has become essentially routine, with surprisingly small HAZ in practice.  Normalizing the structure still is wise, and takes time, but you can literally build the necessary CA 'furnace' in a back yard and fire it with domestic gas...

If you look at the original feasibility plan for 5550, the 'default' was always to be lost-foam castings and waterjet/laser (shipyard cut if necessary) hydroformed plate.  That puts engineered material in place of structurally-indeterminate bulk mass in the engine bed, but keeps the advantages of castings where appropriate (and, perhaps importantly for the historians, allows a certain similarity to the control dimensions of the original).

In some alternate life I was told that GSC cast engine beds in multiple simultaneous pours, with slightly different alloy composition for different parts diffusing together seamlessly.  This was attractive enough that I took it as design 'gospel' until a couple of people with real-world forging experience and historical knowledge of GSC and locomotive builders noted it was done with just two pours... hence the intricate gating, very large excess capacity in it, and the expressed expectation that multiple castings would be needed to ensure a fully 'usable' result.  Personally... I think laser keyhole welding is a better answer today.

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