Boiler starting situation

Greetings.

As of May 2013, the outer shell of the boiler has been surveyed for thickness by ultrasound, and all the numbers are very good. The bottom of the front tube sheet shows some deterioration and a few rivets at the bottom of the flange joining the FTS to the barrel have eroded somewhat. The firebox has been checked in a few places on the crown sheet and above the old firebrick lining, nothing bad found yet, but there are visible patches welded in towards the bottom of the side sheets. ALL the radial crown stays are of the Baldwin Expansion stay deign, sort of a forged stirrup coming down from the wrapper sheet and a shaft coming up from the firebox going through the stirrup and secured with a nut. Drawing will be posted as soon as I can figure out how.

One of our guys is limber enough to fit into the boiler trough the dome, and while there's no lack of red clay scale as one would expect from Georgia water, he reports the braces, internal surfaces and stays look good generally. The throttle valve is missing the standpipe, we have the double seated spool that fits in to it.

So, I think initially we can start working on ways to make a new standpipe or replace the old throttle with something else; how to determine when to replace eroded rivet heads or ways to repair them; and best practices for cleaning an surveying boilers.

We might also want to think about any alterations that would make for more efficient heat transfer and circulation.

Sounds like a good start. How far are we allowed to go on the boiler for the sake of efficiency? We had discussed adding several transverse arch tubes privately, and it sounded like there was little desire to make major alterations to the boiler. Therefore, I'm guessing superheating, feed water heating, and a front end throttle are all out, although I really like the idea of making up a Chambers front end throttle for her. This would allow new, larger branch pipes to be installed, as well as a centrifugal separator on the dry pipe for drying the steam.

Due to the short amount of full throttle running, I don't think you can justify a feed water heater. However, if you can, I would suggest a scaled down Elesco could be kludged together. The heater itself could be easily fabricated, and I think you could modify a 9" compressor to work as a pump. I prefer open systems, but they would be a lot harder to fabricate.

Should superheating be "on the table," the biggest headache would be a header. Texas State has made weldment headers for their new boilers. I'm not sure how much service they have seen, so I cannot speak to any long term maintenance concerns. The units themselves are straightforward, with brand new return bends being available through my employer.

I still like the idea of transverse arch tubes. Compared with any other boiler efficiency modifications, these seem like they would offer the most bang for the buck. Better circulation and more direct heating surface would yield a more powerful boiler. With everything "downstream" remaining the same, a more powerful boiler can be run at lower, more efficient firing rates. The only real modifications necessary would be removal of a couple of staybolts, fabrication of the tubes, and adding doubler plates and washouts on the wrapper. I would suggest Huron washout plugs for ease of maintenance. External visual changes would be barely perceptible.

Flanging a patch for the FTS would be straightforward. Should superheating be desired, or should UT reveal more problems with the FTS, I would suggest removing the whole thing and replacing it with an unflanged weldment tubesheet. These were common towards the end of steam. I believe most if not all welded locomotive boilers were built with these. ATSF 2926 has one, and I believe the N&W used this design extensively as well. Fake rivets could be applied for cosmetic purposes.

I think we shouldn't limit ourselves in terms of what's theoretically possible while we kick around ideas.....not every locomotive is 110, and for others it could be very worthwhile to think about such things as front end throttles. It would be nice to know what's possible and how it could be done and what difference it could make.

I don't think from a practical perspective we're going to do major alterations to 110. First, the boiler seems largely in good condition so far, and NHVRR isn't in a position to devote a lot of money to fixing what isn't broke. So, smaller alterations like arch tubes or circulators? Much more possible, especially if we find we need to do some firebox repairs anyhow.

Jason Sobczynski had a plan that never materialized to superheat the little 3 foot gage 2-6-2 that was at Georgetown Loop a few years back. I don;t know whether that would have made any difference....or if it was everr quantified in some way.

Dave

As I also said in the cylinder starting thread, I don't see a great need to superheat this locomotive for the service intended. I would definitely concentrate on better circulation, perhaps pumped circulation a la Cunningham, and on air preheating a la Snyder, neither of which requires much complexity or compromise to appearance, and either of which removed if desirable.

Something I would do, however, is look into treating the inside of the boiler with one of the passivation approaches we discussed over on steam_tech (electroless nickel, etc.) It would help if there were a jig large enough to hold the boiler and rotate it to different angles, like the fixture used to assure consistent downhand/submerged arc position for welding.

Are we going to use Porta-McMahon treatment on this locomotive in service?

The drawing for the boiler was damaged in a fire at the Vulcan plant, and it's only half the boiler now.....but the same boiler was put on two locomotives Vulcan built for the Marion Railway, and we hope to get a copy of a good drawing from one of those files. Nick the archivist is going to track it down eventually.

The Porta McMahon program isn't practical as its requirements run contrary to FRA regulations about such things as frequency of washouts, etc. I had some correspondenc with Shaun a few years ago when I was at the Loop.....and we kicked around the concept of removing the treated water, filtering it, and reintroducing it after washouts as a way to get around it and make it 'legal." The infrastructure necessary to be used for one locomotive a few times per year.....probably not likely in this particular situation. If we were Strasburg or D&S it may be a very different situation.

I'm not sure what treatment program is being used in 17 now. Dave Dick could tell us about it. I've been leery of the Terlyn stuff because the guy selling it was a greasy creep, and nobody could tell me how it worked. I set up a working program based on weekly testing at the Loop, but we ran daily for months at a stretch and that isn't today's NHVRR either.

Perhaps introcducing a sacrificial anode of some sort and figuring out how to test and treat the water in the storage tank before it even gets to the tender is the place to start.

Dave

I have been thinking further about the superheater question, and still think keeping the engine saturated is wiser. The expected operating profile, with those relatively low drivers, means a wide range of throttle opening and cutoff variation. New superheaters would have to be sized and proportioned to work effectively across that range 'automatically' -- and this in a boiler with new gas speeds, flow patterns, firing modality. The Superheater Company had the empirical data and expertise to do this correctly, without needing recourse to dampers, but I am not sure (after the abortive RyPN contretemps last year) that there are any people with access to that wisdom now --and those with the knowledge may not know how to apply it in this context, for a reasonable cost.

Fuel and water saving from superheating will likely not pay the design charges. If the throttle is not relocated, the superheater would have to be certified, and safetied, as a separately-fired pressure vessel. And you might have all the problems Blue Peter and others have with water carryover into the superheater causing trouble that doesn't have to be there.

I think I'd concentrate more on ensuring that saturated carryover has minimum consequences. And make the thermodynamics elsewhere more efficient, as that can be done more cheaply and far less irreversibly. But that's just me. (You can always go in and superheat later, when the flow patterns and characteristics for the 'rest' of the rebuild are complete...)

Since the drawings haven't been uploaded yet, I'm doing a temporary workaround by loading images of the drawings to my Photobucket account. Here's the boiler drawing in JPEG format:



Looks like this is workable for discussion purposes. I'll post details of the exhaust and smokebox in the appropriate thread.

I had been assuming that recirculation of the Porta-McMahon water would be necessary, not just for FRA 'nudge, nudge, wink wink) compliance but for maintenance purposes. Pump it out into an insulated holding tank, pressurizing the boiler and filling/purging with nitrogen or dry air as you go. Rinse as desired through pressurized fittings. Inspect the boiler at leisure in the dry, without letting it cool down too far. Filter as you run it back in the next day... deoxygenate, and away you go.

This needs a large (enough) heated and prressure-rated tank, but bypass through a water heater element as done on 8055 will keep you right up to saturation pressure in holding. Transfer back to the pressurized boiler requires little pressure head and involves no flashing to steam, or hammer in the lines, etc. (And you test the pops with the departing gas as the system comes up to pressure....)

I think something like an ACFI tank feedwater heater, or something like the Wilson Water Conditioner on the MILW F6s, would be a better approach than trying to mount something up at the smokebox end of 110. I have changed my initial opinion: I think it is highly beneficial to have FWH on a saturated engine, which is using a higher mass of water in the first place. In addition, we have a relatively small front end but want to reduce back pressure: what better way to help with this than condense some of the exhaust steam in the incoming feedwater (along with what is used in the Snyder air heaters)?

Is there any advantage in sourcing an English ESI and putting it on this locomotive? It's the right size for it...

I vote for arch tubes, if this is a democracy. I would NOT vote for circulators that set up any disturbed flow pattern near the location of the steam dome.. Or anything even remotely working like syphons. (I am still hoping someone can tell me why ATSF took the two syphons back out of the 3460-class boilers so quickly... and for that matter what was done with the six welded boilers that were fabricated but never applied... but that is another discussion.)

In my opinion the Cunningham complements the action of the arch tubes to an extent, and the port locations for the Cunningham manifolds should be chosen to optimize flow in the legs that (again) keeps rising water away from under the steam dome. We should conduct some detail experiments on the boiler to determine the actual circulation patterns, in order to fix exactly where the Cunningham 'downcomer intakes' in the convection section are located. The company that made Cunningham's test jet pump is still in business, and might be able to replicate the device or provide detail drawings.

We have NO injectors right now....so if our English or Australian brothers know of an ESI that's available, we'd surely have an interest!

Dave

Just as a note: I vote yes on the welded front tubesheet, and yes to welding the tubes in the rear tubesheet -- just prosser & perhaps seal-weld them in front. Is all the sheet staying in good shape?

What internal inspections we have done - one of our skinniest young guys in on top of the tubes, everything else through washout holes - things look better than expected, and that's very good. There is a lot of red clay scale built up in the legs, so we may find something down there. Braces up top have not raised any red flage so far. Once we remove the tubes and clean all that crud out we'll know a lot more.

Dave

Now that we can look at the geometry of the back end of the boiler.....and given there's not much in the way of a history of water working problems on 17......to what extent do we want to worry about increasing circulation through the firebox?

So.....Mr Zahrt has suggested circulators, and Mr Ellsworth arch tubes or a pumped circulation system. I'm much more a fan of passive paths than mechanical assistance - especially when it isn't a critical problem being solved, but an effort to increase efficiancy at marginal cost.

So, I'm thinking also about the length of the flame within the firebox: the Canadian practice is to put the burner under the door aimed at the area below the tube bundle and use a brick arch, lengthening the fire path into a Z shape. It's apparent that the arch tubes would increase circulation and the extra time the fire has to radiate more heat in the firebox before entering the tubes would perhaps be of benefit.....but I'm ignorant about how the drafting was set up for small locomotives in Canada using this arrangement, and to what extent it would be more efficient. Perhaps our Canadian brothers can tell us more about it.

Dave

The more I think about it, the more I wonder about what I was saying with respect to centrifugal burners.

'Filling in the corners" with a vertical centrifugal is more difficult than with folded-flat. But I have to be concerned that with the available draft, expecting the flame to go cleanly in a Z around a refractory arch in a boiler this size may be like that old Angus Sinclair discussion about 'fooling the steam' to follow the arrows in the patent diagram rather than... go where it goes.

For the Z system to work, you would need HIGHLY laminar primary air, with no infiltration under the firepan at that end, at all, to spoil the flow, and a bunch of very accurately aimed ducts angled forward in the firepan to supply secondary air to the plume as it burns. The usual care against impingement quench at the throat, and time lag as the refractory heats up there (I honestly don't know if having 'arch tubes' in the refractory mass at that point to give it some preheat up to saturation temperature helps or hinders!) and then some more directed secondary -- ordinary 'overfire jets' won't really do the job; you need more directed flow and not 'stall') back up to more refractory high up on the backhead.

This can be made to work in steady-state, probably with high efficiency, given enough time and tweaking. What concerns me is just how variable the draft is going to be, and how long the system's response adjusting to draft changes is likely to be. What immediately comes to mind is that the blower system, or a parallel blower system, be rigged interlocked with the throttle and reverse, so that when running it normalizes the draft against sudden change. It should be simple to design a valve that looks at smokebox vacuum and throttles accordingly -- no need for fancy feedback proportional, as the input signal is already the controlled output. Bleed to allow the proportion to ease up and down over time. What it does during a puff is yet to be determined, but I'd put in some means to delay the burner relighting so the draft has adequate time to purge the box -- about 2 seconds? -- regardless of where the throttle and reverse happen to be set at the time of an 'incident'.

I'd stick with a von Boden-Ingles type of burner geometry here, perhaps with nozzles both below and above the stream, perhaps drilled slightly angled to give some spin, and some turning vanes rather than a straight-sided gap for the fuel admission. The result would then resemble some number of small rotating flows parallel to each other rather than a single conical plume. At least in theory.


However, I have to wonder whether Nigel's vertical burner and strong spiral flow in this little square box is not a better general idea. I would keep the refractory strictly limited and try thermal barrier coatings instead -- you want reasonable heat transfer but a minimum of surface quench. I wonder if the burner could be slung lower, in a cylindrical shell lined with refractory entirely under the mud ring, so that the flame would have time to carburete and ignite fully, against full refractory with a large thermal mass brought up and kept above transition temperature, before it moves up to impinge on relatively cold inner-sheet walls...

Same provision for automatic draft stabilization. I think we may have an approach in principle for cheap accommodation of waste-oil issues here.

Well, we have decades of Canadian experience to find out about before we make a decision about what the problems might or might not be. It's just one option to be considered along with any others at this point.

Just read that Wardale was considering this sort of thing for 5AT but discarded it for similar concerns, but Kloke uses it successfully on Leviathan, and his #1 steam guru is going to start using it on his other projects, so.....worthy of some consideration.

Perhaps we can look at the Leviathan's installation and compare it - i think the sizes will be pretty similar. Might be worthwhile to see if we can get ahold of Leviathan's drawings or even find a time to take a ride.....check it out in person.

Dave

I think you are right -- we have Kloke's experience on the one hand, and Nigel Day's on the other. (And if we are gluttons for punishment, SLM/DLM with the rack-engine burners; there are some shots of the stainless burners on the Web but IIRC they're in an academic page that you'll have to hunt for)

What I'd design for is the minimum required heat input, and hence the smallest geometry, with the secondary principle of reducing differential thermal stresses in the firebox structure (both in steady-state firing and transients). It seems possible to me that on a locomotive this size some of the automobile-size pressure-burner designs might be adaptable, and I think we should keep that option open and form some ties with folks in SACA and elsewhere with distinctive competence or interesting ideas.

Is it really possible to mount arch tubes?? How do you weld them in a riveted firebox? What is the quality of the tube plate? Visually inspected or measured?
Regards
Jos

As for water treatment, since the locomotive has a fixed operational base, why not arrange for a small water treatment plant. Chemically soften the water, filter by reverse osmosis, add oxygen scavenger and use it. The plant capacity to be enough for replenisment on a 24 hous basis which is surprisingly small. Almost all of the Dutch heritage organisations are working this way and you would be surprised to see how clean the boilers remain. I'll try and see whether I can post a photo of a 30 year old almost immaculate boiler tube.
regards
Jos

Thanks, Jos....I'm very happy to see your posts here.

This stage of discussion is casting a wide net about what is theoretically possible and then some. We have not yet done the teardown and inspection that would be required to have all the relevant answers in hand. This is done purposely by our marketing people as part of their concept of fund raising starting with a June 2 event at which 110 - appearing complete and in a new donated coat of paint - will have its program officially inaugurated. Crew is tied up with operating 17 during work sessions through the summer, but boiler surveying work has been sketched into the schedule starting towatds the end of summer. The entire outside shell was ultrasounded before the paint went on, and the results were pleasing. I don't see us getting into a lot of mechanical teardown until perhaps September or October, but if we need a specific answer on a priority basis, something can probably be arranged. .

Your experience with water treatment is very like mine at georgetown Loop - when I started there we dumped in gallons of stuff, and washed out every two weeks. Installing a water softener in the line filling the storage tank from the local mains combined with weekly testing cut our treatment amounts dramatically, and allowed us to set treatment and blowdown schedules according to real timely data.

NHVRR trucks in boiler water since there's no productive well with adequate flow. This may change....but it allows us to start with decent quality water to start with. Dave Dick can tell us about the additional treatment program in use now on 17. After several years of work the tubes are in good condition.

Suggestions for including circulators and arch tubes were placed on the table for discussion. Arch tubes in the US were generally rolled and expanded into place through holes with large screwed in plugs in the throat and backhead. Welding is of course better used today than in the 1920s. We customarily make welded repairs to riveted boilers, so from a practical and regulatory perspective there would be no difficulty providing the calculatiuons were good.

Dave

More naivete here. Why are we even discussing feedwater heaters and superheating? No. 110 is a little backwoods logging engine, not a main line speedster. Will we realize sufficient efficiency and operating cost reduction to make such modifications worthwhile? I mean, as it stands today, No. 110 would be run a couple of days a month. It seems to me the payback would be a long time coming.

We're discussing them because they might be possible or worthwhile if not here and now somewhere and it's good to know about options - even though some options will be discarded down the line. I see a future role as bad cop for me when it's time to start reducing options rather than engouraging them to be mentioned and considered.

So, something about superheaters that Strasburg posted on Railway Preservation News a few years back comes to mind - Strasburg has a run that is similar to ours in temrs of length, etc.....they just run lots more trains lots more days and c arry lots more people. Anyhow, they had just restored a superheated locomotive and found that there was no advantage in terms of efficiency compared to the saturated locomotives. They were sorry they hadn't just saturated it and saved a lot of money and trouble........I remembered an article form many years back in which it was shown that superheaters require the locomotive to be run for some length of time at a fairly high level of power before the superheaters gain enough thermal advantage to provide much efficiency.

So, perhaps it isn't a worthwhile solution for us - but if there's contrary evidence we should hear about it if anybody wants to post it.

Dave

Just got word from the archivist that no files for either of the Marion Railway locomotives survived....so we're stuck with the half of the boiler drawing that did survive the fire, fortunately the more nteresting half.......at least until we remove the tubes and measure and draft a new drawing this fall.

Dave

DaveLathrop57 wrote: ... (Strasburg) found that there was no advantage in terms of efficiency compared to the saturated locomotives. They were sorry they hadn't just saturated it and saved a lot of money and trouble........I remembered an article form many years back in which it was shown that superheaters require the locomotive to be run for some length of time at a fairly high level of power before the superheaters gain enough thermal advantage to provide much efficiency.

I think any real advantage of superheating for an engine as small as this one isn't efficiency per se, it would be lessened problem with carryover and condensation in the cylinders. The situation is a bit complicated by the small driver diameter, which may put the cyclic rpm up to where superheat gains begin to look attractive in some sense.

I repeat that I do not think superheating is at all a priority on this locomotive, even if other methods like FWH or air preheat are installed. Just too much fabrication, too much (likely) subsequent maintenance and potential points of failure, and (unless changing to a front-end throttle too) the safety risk involved in water carryover into the elements and subsequent temporary loss of throttle authority.

So, perhaps it isn't a worthwhile solution for us - but if there's contrary evidence we should hear about it if anybody wants to post it.

I am certainly interested in hearing about it if justifiable and cost-effective.

Let's look at the air preheating idea a bit more closely - what do you have in mind?

Dave

Basically, this is a modification of the Snyder preheater. Multiple rows of coils or fin tubes at the edges of the pan or where air is entering. Runs on exhaust steam with small bleed from turret or boiler to prevent freezing.

The alternative is to run heat pipe exchangers from an extended combustion-gas pass to the air intake. This has the theoretical advantage of enabling any desired degree of FGR (the Rankine equivalent of EGR) when that is desirable. Heated air (in counterflow) goes through ducts to the places needed. Draft pulls it in proportionally.

Some air preheat would be needed for secondary air if the Z "Canadian" firing is adopted -- this might be provided through a 'feather' of parallel pipes with thermal barrier coating projecting above the burner. Airflow cools the pipe and heats the secondary air simultaneously, with little equipment cost as far as I can see.

So, if I understand you correctly, we could use the preheater to also aim the airflow much as Nigel's firepans have done with the floor mounted burner? Very interesting...

Dave