Very interesting video. Note the use of “hardware store” vermiculite panels to fabricate an arch.

English subtitles are provided.

https://youtu.be/jT1ApY4YLhU

Sehr Gut !!!!

Fascinating and very well done, both the experiment and the video. What I really like is that with a little tweaking of the grates and drafting arrangement, this fuel conversion is practical. NO computerized fancy doo-hickies seem to be required....

Thanks for posting. Vielen Dank !!!

Much of what this actually represents is a modern version of comparative firing with coal and wood (remember wood as an alternative fuel, for example (somewhat abortively, as it turned out) with eucalyptus in Australia?

The 'better' solution for this type of pelletized fuel was well-established 2 to 3 decades ago, and was a hot topic in the power industry for 'clean coal' implementation; most of that intellectual property would likely be out of patent protection by this time.

The key approach is torrefaction (one of the comments in the YouTube video disguises this as "bio-coal from a pyrolysis reactor') which recovers the volatiles and reduces the mass of the feedstock so that it's principally carbon and properly-fluxing ash constituents before the 'pelletization' step. Much of the original preparation concentrated on pellets rather than briquettes (which were and are a more direct method of firing a legacy steam locomotive) because the idea was to co-fire the torrefied material with some form of pulverized coal, so the smaller form factor and greater exposed surface area were not a negative concern.

What extended testing should be conducted to establish is what larger briquetted size of torrefied product could be best used in alternative applications -- pellet stoves, for example -- and provide the best combination of first cost and effective distribution necessary for a good solid-fuel alternative. The follow-on (fun for people like me!) would be to apply some of the solvent-refined coal (SRC) processes, some of the most successful of which are also out of patent, to reduce the absolute ash composition and percentage of renewably-sourced torrefied product.

But does it smell like coal?

Having truly enjoyed the day at the CSR's first Everett Railroad testing, including having my hair scorched by hot embers, and having to leave for home before the rescheduled testing, which was due to other embers setting a small smoky sideline fire, I posit there's a little more involved than pellet size. What the effects of the binder is important too.

Perhaps this helped lead to CSR abandoning the project.

Brian Helfrich

There's a LOT more involved with practical torrefaction and the use of the product effectively in 'legacy' locomotive firing. Personally, based purely on the comments surrounding Project 130, I never had the impression the CSR/SRI people ever really understood what had been done with torrefied combustion fuel up to that time; they seemed to think they were breaking incredible new ground in locomotive fuels.

In a sense, they 'could' have been right: effectively-prepared torrefied wood could (relatively easily) be briquetted using similar methods to the soft-coal briquetting used in Europe a century ago (in part for smoke reduction) -- you size the briquettes to, roughly, good 2" washed coal with the right 'surface finish'. Historically briquetted fuel was considered a 'non-starter' because it cost more than run-o'-mine coal such as abortively considered for the ACE3000 -- that certainly doesn't apply for most modern heritage operations, particularly those currently suffering a shortage of proper steam coal from Eastern Europe or Russia.

The point about the torrefied pellets was that their form factor was intended for 'clean coal' firing with common sizes (and rakns) of pulverized coal in large once-through utility boilers -- supposedly the ash content and any additional 'clean coal' additives like dolomite would be incorporated into the product before final grinding and admixing. YOU DO NOT WANT A PELLETIZED FUEL IN A LOCOMOTIVE SUBJECT TO SUDDEN HIGH DRAFT -- whether that draft is periodic, as at starting with gear 'in the corner' and quickly-opened throttle, or during a slip. Most of the 'stove pellet' material I've had my hands on is relatively friable, and can be expected to behave at least substantially like the subbituminous coal fired in the Big Boys in service -- breaking apart, burning in the combustion plume over the fire and not completely consumed while luminous (leading to sooting and, if the fragments are large enough, reignited 'sparks' similar to those for wood firing. You want lumps that stay close to the firebed, that scrub off carbon that gives luminous radiation -- not the moral equivalent of defective oil firing that is not using oil controllability.

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At least one tourist operation in the US used briquetted coal; I visited the Laona & Northern during the 80's and was surprised to see the tender of the little Vulcan 2-6-2 loaded with what looked like bar-b-que charcoal, but bigger. Turns out it was bituminous coal, appearantly briquetteing was a good way to reclaim the dust at the bottom of the holds of the lakers that brought it north.

Would a heavy duct arrangement that wraps around the back of the grates and moves the air from below the grates to above (I am thinking of a C-shaped thing the width of the grates) do the same thing as the elaborate blower in the firedoor? I have a lot of experience with wood stoves and drafting but none with steam locomotives, so I may be way off.

Remember that the fire in a locomotive boiler is almost nothing like that in a typical pellet stove. The latter runs in a heavily reducing atmosphere (very stingy primary and secondary air) so that only a relatively small amount of 'space heat' is released over a ptortracted time. While a typical induced-draft locomotive firebox also runs almost wholly below atmospheric pressure, there is an enormous mass flow of combustion products moving at what can be very high speed, first to sustain radiant transfer and then to provide good turbulent convection and conduction in the tubes and flues. Dried and especially resinous wood is able to produce prompt flame, but it is not long-lasting in the way a substantially carbon flame is.

You're right in that a great many dampered tuyeres under the firegrate, perhaps even a windbox arrangement or even some steam injection, will provide the "best" combustion-plume generation in a typical arch-equipped locomotive firebox. Whether you then need careful overfire or secondary-air intakes in strategic places is a detail-design question -- see some of the stuff Porta did for 'biomasa' and look at (for example) the B&W discussions of bagasse furnaces (and the tuyeres and underfeed those often use).

Personally I can think of little more stupid than a forced-draft fan located in a firebox door. If you had a toy firebox without an arch, that might kinda-sorta work, but something I'd avoid with crosses, garlic and silver bullets is any sort of positive-pressure combustion in a Stephenson boiler -- not that they aren't an interesting idea thermodynamically, just that they're dirty as hell and have all sorts of gas leaks out and air leaks in. If you have to have a fan, rig it like the one in the South African 25 class, pushing up from under the gas plume as it exits the front tubesheet area, and does not run in the abrasive ashes and hot sparks. (Don't rig it in the smokebox door like the English Southern Holcroft-Anderson engine either... not that I need to tell you that).

I also suspect that engines like the one described require very deliberate, almost pussyfooting control over throttle and reverse to keep the 'fire' from levitating toward the stack, probably developing holes as that happens...

Once again, I'm afraid that I will reveal my ignorance with this question, but WTF is a tuyere ?? (My spell checker doesn't recognize this word, either.) It isn't in Webster, although I looked between tuxedo and twaddle, and the great ALCO design engineer A.E. Bruce doesn't include that word in the very comprehensive index of his magnum opus "The Steam Locomotive in America". Thanks in advance for any enlightenment you can provide.

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From Merriam-Webster:

Thanks to both you gentlemen for your replies. My dictionary says "Webster's II" on the cover... guess in plain English that means: Merriam-Webster LITE.

Sammy, the technical use of 'tuyere' can be found in a number of places, including IIRC the original operation of the Bessemer converter. Some of the underfeed-stoker designs involved them. But the best way to understand the idea is to go to your handy compy of "Steam: Its Generation and Use" and look at the section on bagasse firing, which has much of the technical detail on the operation.

For the specific appli8cation of oil firing: There are or were some good pictures on the Web showing the Dickens' Barker burner on 4014, at least one of which shows both the convergent fire walls and tuyeres they use ahead of the burner arrangement.