# 451
Some out of box thoughts on steam. I will start this by saying I am not an engineering student or any kind of expert. But that having been said I can maybe think of things out of the box. 1st thought. If a way could be found to increase the available torque from the format of a shay or climax type locomotive. With a rod geared locomotive I would think that a lot of problems associated with trying to balance the main drivers. The other advantage they had was like diesels they had all the weight on the drive wheels and did not need pilot trucks. 2nd thought. A steam turbine with the ability to adjust the jets against the blades. Combined with a blade that had different pitch from root to tip. Instead of adjusting the pitch of the blade have different points at which the steam nozzle was aimed at the blades. This way you could get more leverage at one point but as you increased speed move the nozzle to apply force at a different point on the blades. Essentially providing a way to change gears. This is kind of hard to describe and maybe someone has thought of this already. But as I said I am no expert. Last thought on this is think of how a variable pitch propeller works on a n airplane. The difference being is the propeller does not change pitch but where the steam is applied to the is changed. Thx IGN
# 452
Injecting steem into a turbine is not all that different from injecting steam into a reciprocating steam engine's cylinders. The steam pushes the whole face of the piston, not just a specific area close to the valve inlet. The same applies to turbine blades.
But there is different approach that night work. On a large and wide turbine, don't just have one inlet port and one outlet port around the circumference . Have four pairs. Control the steam so you have only say the intlet port at 3 dgrees and the outlet port at 357 degrees for low power, the inlet ports at 3 and 183 degres and outlet ports at 177 and 175 degrers for half power, and inlet ports at 3,, 93, 183, and 273, and outlet ports at 87, 177, 267, and 357 degrees for full power. Has anyone built such a turbine?
daveklepperBut there is different approach that night work. On a large and wide turbine, don't just have one inlet port and one outlet port around the circumference . Have four pairs. Control the steam so you have only say the intlet port at 3 dgrees and the outlet port at 357 degrees for low power, the inlet ports at 3 and 183 degres and outlet ports at 177 and 175 degrers for half power, and inlet ports at 3,, 93, 183, and 273, and outlet ports at 87, 177, 267, and 357 degrees for full power. Has anyone built such a turbine?
Dave, look at the control-nozzle arrangement on the Met-Vickers turbine in the "Turbomotive". This does the important half of what you propose.
For engineering reasons, there is little if any point in arranging multiple outlet ports on a turbine this size. The exhaust involves very large plena with progressively increasing volume, and the orientation of multiple plena is going to involve some iteresting packaging to get it in line with the draft-producing apparatus in the front end. (While I am a fan of Holcroft-Anderson 'recompression' to utilize the latent heat of vaporization in the Rankine cycle, I am not particularly hopeful that a 6000+ hp turbine can be meaningfully condensed with meaningful overall cost-effectiveness...) I invite you to calculate just how many degrees the exhaust plenum represents, and why a single plenum served by multiple throttle nozzles was chosen.
Note that at least one proposed approach to this kind of turbine involves a pair of turbines, sharing a mainshaft and central drive pinion. Inlet is inside, close to the pinion; the large exhaust plena are outboard, where there is ample room for them. and the reversing is handled internally. In all probability these turbines would combine impulse and reaction -- the original design I saw had an initial impulse stage, and then multiple reaction stages; the modern equivalent would blend these from blade root to tip. It would be technically possible to bleed steam at different stages to optimize feedwater heat, and Erik will probably have something to say on running a heat balance on such a design and on whether the added work is worthwhile on something this small (in overall turbine terms).
# 454 - classic long standing Chevy BigBlock
on 451
What you aim at is a full adhesion geared steam motor concept - something that could have been done and would in fact have made steam competitive to diesels on a 1 : 1 basis of serviceable locomotive mass as far as starting tractive effort and limit by adhesion factor on rail is concerned - however , not likely so in view of power output per unit of serviceable locomotive mass . Or on the other hand , first generation diesels were so low in motor power they had to use a considerable part of it only to propel themselves at speed , so maybe an excellent design of the above mentioned might have stood a chance ; however , then again exactly *that* was the problem of steam locomotives of this unconventional concept : there *was no* excellent design realized and hardly could be expected in that preciously short a development time as at best available for steam at the onslaught of dieselization .
Your ideas on steam turbines I'd rather not comment - we may all have dreams , why not .
on Daveklepper # 452
>> Injecting steem into a turbine is not all that different from injecting steam into a reciprocating steam engine's cylinders <<
Oooh - it's a totally different story !
on Overmod # 453 ( please put in your # )
>> Dave, look at the control-nozzle arrangement on the Met-Vickers turbine in the "Turbomotive" <<
While the comment is basically aiming at the right direction , obviously Dave does *not* have drawings of the >> Met-Vickers turbine of the Turbomotive << and so he can't look at them .
a - >> there is little if any point in arranging multiple outlet ports on a turbine this size <<
b - >> wether the added work is worthwhile on something this small (in overall turbine terms) <<
How does -a- fit to -b- ? seems the turbine has shrunken considerably over the lines - *g*
>> orientation of multiple plena is going to involve some iteresting packaging to get it in line with the draft-producing apparatus <<
Again it would be nice to state which are the packaging that seem so interesting . btw what exactly is >> interesting << supposed to mean : difficult to design - a challenge to manufacture - offering thrilling aspects in adjacent design ?
>> I am not particularly hopeful that a 6000+ hp turbine can be meaningfully condensed with meaningful overall cost-effectiveness... <<
It can be done one a 2000 hp steam loco's tender - and thus it can be done on a 6000 hp steam loco's tender , it's simply a question of proper dimensioning .
>> I invite you to calculate just how many degrees the exhaust plenum represents <<
Would be interesting to read the results of *your* calculation , after all you let on you have done some already ?.
>> technically possible to bleed steam at different stages to optimize feedwater heat <<
That's right : it's *possible* - yet as preheating is being optimized , expansion / utilization of steam in the power turbine is being compromised - an idea that has been common in steam power houses - where conditions differ vastly from those found on a steam locomotive , namely in the locomotive heat energy generation and utilization has to be designed much more compact and at the same time more simple and robust to suit purpose .
>> Erik will probably have something to say on running a heat balance on such a design <<
Ok , Erik , looks like it's your turn now .
( part of third paragraph deleted by = J = Oct 30th )
Regards
= J =
# 455
Juniatha, could you explain to me (and other readers) the basic difference between injecting steam via piston valves into a reciprocating steam locomotive's cylender, and via the intake port of a steam turbine? Other than the fact that the intake port is continuous in operation while the piston valve opens only a fraction of the time, the fraction depending on cutoff setting. What I don't understand is the idea the the steam from the intake port could exert force on only a portion of the blades and not the entire blade area.
# 456
Essentailly, in a Turbine, each blade has the function of both the piston and the valve in a cylinder, since it receives steam (or gas or water for that matter in water-wheel) only at the time when it has just past the injection port and the time that the next blade passes. I imagine there must be a difference in the way the steam forces the blade forward and the way the steam forces a piston forward, or otherwise the differnces in blade ;profiles would not amount to much, and yet choosing the right blade profile is an important part of turbine design. I don't know of any locomotive cylinder pistons that were not flat-faced. Were there any?
One other idea. Are not entrance ports on turbines always on the circumference? Suppose there were five entrance ports, two on each side within the area swept by the blades and one on the circumference. Then would not choice and number of entrance ports used have the same degree of control as changing blade profile?
# 457
Dave
these questions enter thermodynamics and conversion of thermic into mechanic energy and should receive a more complete answer . I would answer it , however I first must see when I will have time to spend . As things usually are , I'd expect before I even open up trains forum next time , Overmod will have posted a 100 lines reply ...
Uhm , Dave I have just sent you an e-mail with a quick reply for now .
Juniatha
.. and I would really really appreciate if each participant could put up that counting # on top of his post again - thank you all .
# 458
Following up on Juniatha's email, I investigated a website, and I will leave it to Juniatha to post the reference. I found that I had forgotton whatever I had learned about turbines at MIT. I was thinking of a turbine as something like a waterwheel, that powered much New England machinary, pipe organs dating back to possibly the "Hydraulis" that some say was an organ in the 2nd Temple in Jerusalem, but a turbine is very different. The individual blades receive fresh steam (or gas) around the entire circumference, with alternate fixed and rotating blades shaped to create the torque and the rotary motion.
Power is controlled by something analogous to a throttle, and generally the turbine operates at maximum efficiency and minimum noise at its rated rpm and at or near maximum load.
But this is like running a conventional steam locomotive with only the throttle to control power and no "Johnson bar" (reverse lever). A locomotive engineer that completes a run with the bar "in the corner" all the time might well be fired for using far too much fuel, and possibly creating other problems in the locomotive as well.
There should be a way to provide "cutoff" in a turbine. Imagine each rotor has 16 or 24 or 36 or 48 blades. Full power has all openings open, reduced power one out of four around the circumference closed (entrance and exit, staggered appropriately) further reduction, half closed, and minimum power only one out of four remaining open. The result should be a turbine that can operate efficiently at different power levels. Constant speed or not is another question, since power is torque times revelutions per minute (times a constant), and answering that question takes more turbine designing skill than I claim to have.
If there is any monetary reward for this idea, Juniatha should certainly share! It is simply applying a lesson in reciprocating steam design to turbine design, and it should apply to gas as well as steam turbines.
# 459
after "closed" - first appearance, should be inserted "(entrance and exit, staggered appropriately)".
I will now make the correction using the edit mode.
# 4-6-0
daveklepper Following up on Juniatha's email, I investigated a website, and I will leave it to Juniatha to post the reference. I found that I had forgotton whatever I had learned about turbines at MIT. I was thinking of a turbine as something like a waterwheel, that powered much New England machinary, pipe organs dating back to possibly the "Hydraulis" that some say was an organ in the 2nd Temple in Jerusalem, but a turbine is very different. The individual blades receive fresh steam (or gas) around the entire circumference, with alternate fixed and rotating blades shaped to create the torque and the rotary motion. Power is controlled by something analogous to a throttle, and generally the turbine operates at maximum efficiency and minimum noise at its rated rpm and at or near maximum load. But this is like running a conventional steam locomotive with only the throttle to control power and no "Johnson bar" (reverse lever). A locomotive engineer that completes a run with the bar "in the corner" all the time might well be fired for using far too much fuel, and possibly creating other problems in the locomotive as well. There should be a way to provide "cutoff" in a turbine. Imagine each rotor has 16 or 24 or 36 or 48 blades. Full power has all openings open, reduced power one out of four around the circumference closed (entrance and exit, staggered appropriately) further reduction, half closed, and minimum power only one out of four remaining open. The result should be a turbine that can operate efficiently at different power levels. Constant speed or not is another question, since power is torque times revelutions per minute (times a constant), and answering that question takes more turbine designing skill than I claim to have. If there is any monetary reward for this idea, Juniatha should certainly share! It is simply applying a lesson in reciprocating steam design to turbine design, and it should apply to gas as well as steam turbines.
You seem to be describing a "Multi-port Governor Valve"
http://en.wikipedia.org/wiki/Steam_turbine_governing
"I Often Dream of Trains"-From the Album of the Same Name by Robyn Hitchcock
# 461
The idea is that the steam or gas stays a bit longer in each stage before being exhausted and replaced by new steam or gas as the turbine revolves
# 4-6-2
Some random comments.
The multi-port throttle valve is standard for power generation steam turbines, where high efficiency at low power settings is imperative. The valve allows the steam flow to be directly proportional with torque from around 10% to 100% of full load. Note that for a reciprocating steam engine with variable cut-off, the steam flow is more or less proportional to the shaft power. I'm not sure of the multi-port valve does much to reduce steam flow at lower shaft speed for a turbine, something more exotic sch as the variable incidence stator blades used on the J-79 compressor may be called for.
- Erik
#463
Let's please number our posts-it takes only a few seconds!
Ref. 451:
narig01But that having been said I can maybe think of things out of the box. 1st thought. If a way could be found to increase the available torque from the format of a shay or climax type locomotive.
The problem with Shays is that they must have an offset boiler to provide room for the cylinders, limiting boiler size. And Climaxs have trouble adding cylinders.
We have discussed a "Hyper-Hiesler" before, this consisted of a 45-degree V8 underneath a Berkshire-type boiler. Transmissions connected the trucks to keep driveshaft speeds reasonable.
Lima built Shays, if only another major builder (ALCO?) picked up Hiesler planning to sell logging locomotives and decided to build a mainline version...
And now back to turbines.
# 464
It is possible that the variable blade is a better approach than mine is. Have any steam or gas turbines been built with variable blades?
And maybe, just matybe, such a turbine can achieve a comeback for the steam locomotive:
Diesels have two advantages, lower fuel costs from greater efficiency, and lower maintenance costs.
Lower fuel costs:
I have read and been told that North American has huge reserves of natural gas, and that it will be by far the lowers cost fuel on a dollars for energy basis in the future. So possibly the the firebox should burn natural gas? Means of course, a huge tender. But what is the problem with a huge tender? 75-80 feet long with a 12 or 16 wheels? And of course all kinds of safety devices to douce the fire in case of leaks.
Lower maintenance costs:
Boilers, tubes, everything built of the best materials, and water treated. This with natural gas should reduce much of the maintenance normally associated with steam. The goal is a locomotive that when dissembled for its first FRA mandated thorough boiler inspection shows zero measurable erosion of firebox walls or anything else, including tubes, with all dimensions like new, allowing acoustic and electronic testing to be employed subequently instead of a complete teardown.
I would opt for staring with the PRR S-2 instead of the N&W John Henry as a basis. I know well the advantages of electric transmission, but it adds a lot of costs, and even with ac a bit of maintenance. Assuming the new turbine can operaton efficiently at variable speed, I'd use it in a new "T-2", a 4-8-4 based on the S-2 design, with lighter and stronger and longer wearing steel everywhere, buring natural gas. But an alternative prototype with electric transmission might also be bult, with the electricals straight from modern ac diesel practice.
The end goal is a loco that is less expensive to build and less expensive to operate than a modern diesel for heavy passenger and intermodal freight service. Burning natural gas should make pollution control simple, since most of the product is water vapor and most of the rest CO2.
Dave, I like the way you think. No reason it couldn't be done. As a matter of fact, a LOT of live steam amusement park locomotives (Busch Gardens in Williamsburg Va. springs to mind) use propane to fire with. Get a close-up view and you'll see a number of gas grill propane containers in the tender, a bit comical until you realise there's method to the madness.
These aren't tiny locomotives by the way. They're three-foot gauge and of an impressive size. I know, I've ridden behind them.
For equipment for testing of boiler flues without teardown, one possible website is:
www.acousticeye.com - if it still works. Haven't tried it in a while.
#467 (I think)
The ASTM standard for acoustic pulse reflectometry is here:
http://www.astm.org/Standards/E2906.htm
I find it a bit difficult to imagine burning natural gas in a firebox is the best use of that fuel, in a number of respects. Surely the better approach is to use GTCC with steam as the bottoming. That gives you mechanical power from the combustion as well as the exhaust heat... You might use some direct burner input into the HRSG for transient operation, but not as a baseline.
My comment to Dave concerning plenum angle was not a design note -- on Curtis turbines the exhaust plenum is essentially full-disc. What I wanted to get him to see was that even if you had a more 'positive-displacement' approach, the exhaust plena would be so large circumberentially as to occupy many degrees of arc, not just the precise one or few degrees he was indicating.
Most current steam turbine designs are axial, and full-arc admission is recognized as an advantage in them, both in terms of efficiency and in terms of machine loading. It can be argued how much of the advantage would scale to locomotive-sized turbines, but it might also be remembered that speed and load changes (and associated heat effects in materials) are much more rapid in locomotive service than in almost any stationary application. There appears to be a considerable amount of discussion in the recent literature about best ways to implement full-arc turndown; GE for example has a patented approach that appears to involve multiple nozzles acting on different stages.
My understanding is that most modern steam turbines don't use variable-geometry blading. Part of this probably involves seal design in a steam environment -- packing and tip sealing are troublesome enough even before you introduce blade-angle change (perhaps a combination of GE's variable-clearance positive-pressure packing and some modern variant of a brush seal would let the approach work?)
Ordinary exhaust diffusers and hoods are difficult enough to design. Having several plena all capable of handling high-Mach exhaust flows and minimizing leaving loss would be ... interesting. Not impossible, mind you, just requiring more hardware and software for combining CFD and CAD than I have available to me. (Arrangement would be a modified mutual spiral; you would model the plena with lost-foam to construct the ducting, etc.)
Staged bleed for feedwater heating on locomotives was considered as far back as the ACE 3000 project (it is specifically called out in the list of patent references, for example) so I am not quite sure what part of the approach is supposed to be inapplicable to small-package design. (Please do recall, however, that I carefully made clear that it was 'cost-effective' design that was the chief criterion.)
On the other hand, extrapolating from a 2000hp condensing design (I presume this is supposed to be the class 25, although no hard reference was given) to a 6000hp design, as if nothing more than 4x the cooling area were required, is rather daring. There is much more to effective condensation than a quick review of heat-transfer mechanics might indicate, but the real issue (as far as I'm concerned) is how the system is designed for non-optimal operation, and 'graceful degrade' in extreme conditions, since very seldom are full-condensing locomotive designs amenable to effective 'switching over' to noncondensing operation -- this was a major concern about the ACE 3000, for example. On the other hand, no one would be more delighted than me to see details of an efficient 6000hp full-condensing locomotive that works.
I had thought about condensing for the T-2 prototype, but thought this could be something added later. Obvoiusly, it is one way to make the locomotive more efficient, not wasing residue heat, as well as reducing water consumption requirements, but it might be wise to leave it off the first design in the interests of simplicity and maintainability.
Possibly based on the speculaton so far, you can suggest how a turbine might be modified to react more quickly to changes in load demand and meet these changes efficently.
And if it is a suitable combustion gas turbine, might it also have road applications as well as rail?
469
Dave, I like your T2 concept, but there's a few things about the S2 I remembered reading about in "Classic Trains."
It seems there was a bit of a leakage problem in the boiler/ firebox area caused by a rapid drop in boiler pressure from 300psi to 100 psi when the throttle was opened. The drop in pressure was caused by a bit of "turbo lag", for lack of a better term. It took a while for the turbine to get up to speed, the steam initially flowing through the turbine blades like they weren't even there. Once the turbine began to spin, no problem, the boiler pressure came back up. A bit disconcerting for the engine crews until they got used to it.
There was also the problem of un-economical fuel usage at low speeds, at high mainline speeds it was just fine.
These problems could probably have been corrected if the R&D continued, but as the PRR was going diesel anyway the whole concept was dropped. Too bad, it's fun to speculate just where it might have gone.
By the way, if any of you out there don't get "Classic Trains" let me recommend it to you. It's a quarterly, but it's jam-packed with stories and info from the classic era of railroading, and the occasional tech-related articles that squash a lot of "old husbands tales." I should have subscribed years ago.
Wayne
#470
Mr. Firelock,
I had to comment on your post referring to the Bush Gardens steamers. The train ride is one of the three attractions which I will voluntarily board at that park (along with the skyride and the boat, I still miss the petting zoo), as all the other contraptions threaten to rearrange my innards.
I love the gentle rain from the stack after that initial blast of very saturated exhaust when pulling out of a station. Those engines are also capable of some of the slowest slips I've ever seen!
OK, that's steam I have seen.
#471
Hi John!
I've only been to Busch Gardens once, but I enjoyed the steam train ride better than any other attraction. I'll have to let Lady Firestorm know the petting zoo is no more, she really loved that attraction. As a matter of fact, the goats were quite taken with HER! Lady Firestorm's got a way with goats, apparantly.
If I remember correctly, the steam locomotives were both of a European pattern, one was named "Duke of York", the other was named "Bismarck". I'd have named them "Hood" and "Bismarck", but that's just me.
The other contraptions re-arranging your innards? I know where you're coming from, I'm too old for that $#!& myself
As one old Jersey guy to another just call me Wayne.
Hello Wayne,
The last I was at that park, there was a third 4-4-0 dressed up in kind of a western motif, could be a former King's Dominion engine.
Maybe I should wander back towards the topic. I found a neat article on steam locomotive improvements to 15" gauge engines on the Bure Valley Railway, somewhere in England. It was written by a consulting firm named Steam Loco Design. I found the article by typing in "steam locomotive cylinder design" and clicking on the "image" thingy. A pleasant plethora of piston valve pictures presented themselves across the screen and I clicked on the image of a brand new piston valve cylinder. I was then lead cluelessly to the source of the photo and the accompanying article. I tried to copy it, but the carbon paper just left a nasty smudge on the screen. Anyway, I found it fascinating. With photos and charts, as well as a few drawings, they explained how they took underperforming steamers and through improvements in valve design, steam passageways and Lempor exhaust systems, they created very capable machines which can cope with surprisingly demanding service. Those Britts really take their tourist operations seriously!
So I guess my point is, if I have one, that conventional, reciprocating steam locomotives still hold much promise. Plus, you must admit, chugging sounds cooler than a turbine's roar.
In closing, would you say that Lady Firestorm is a "goat to" person? Ok, that was baaaad.
What I have been taught by this thread is that even if my idea did work, it would revive the gas turbine concept and not the steam locomotive, because gas turbines burn liquid or gas fuel more efficiently than introducing boiling water as an intermediate medium of power transfer. Makes sense. Sorry I wasted time and spece, especially for Juniatha. So back to more practical uses for steam today, nosalgia and tourism. Until someone comes up with a better idea.
But now I have had some second thoughts about my second thoughts. The whole idea was predicated on cheap natural gas availabllity. If that were the case, the fact that a regular gas turbine is more efricient in turning inherent energy into work than steam would be trivial in overall operating costs, and modern locomotive that is a very advanced form of the S-2 may be lower in first cost when mass produced and far lower in maintenance costs than either a gas turbine or internal combustion.
daveklepper But now I have had some second thoughts about my second thoughts. The whole idea was predicated on cheap natural gas availabllity. If that were the case, the fact that a regular gas turbine is more efricient in turning inherent energy into work than steam would be trivial in overall operating costs, and modern locomotive that is a very advanced form of the S-2 may be lower in first cost when mass produced and far lower in maintenance costs than either a gas turbine or internal combustion.
Are you speculating about a Natural gas fueled reciprocating Steam locomotive?
If so how do you deduce that it would be lower in maintenence cost than a diesel modified to run on LNG (dual fuel)??????????????????
As indicated in previous posts, I would probably prefer a stean turbine design to a normal piston engine, because it is kinder to the track, and has fewer wear points. Going to gas firing removes much of the maintenance work associated with steam. Iinternal combusion engines of all have lots of moving parts and far many more wear points than either pistion or turbine steam engines, which are relaively simple in
comparison.
To rfpjohn"
John, if you want to see something really interesting in 15" gauge Brit steam Google "Romney, Hythe and Dymchurch Railway." I was looking at the website last night, and they've got some gorgeous steam engines working for them. Two have an American look, the "Winston Churchill" and the "Dr. Syn". Yeah, it's THAT Dr. Syn, remember him from "The Scarecrow of Romney Marsh" Disney mini-series?
Also, check out www.traintapes.com for some video of the RH&D. Just a sample, mind you.
Ditto the Ravensglass and Ecksdale
Dave, that's Ravenglass & Eskdale.
(Note that they themselves use the ampersand...)
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