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Steam engine refractory


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Short story is that as part of my job I've taken over a project of converting a narrow gauge steam locomotive from burning oil to coal. One of the problems that has come up is that the ash pan liner is buckling. The theory is that steel wasn't designed to contain hot ashes in close proximity. One solution is to basically weld some wire on the walls and then cover it with a refractory that can withstand the temps and movement that comes with an engine. Any suggestions?

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Could you line it with insulating firebrick like Morgan Thermal Ceramics K-26 IFB?  That way you could change out any portion that might become damaged a little easier. 

Pnut

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On 2/4/2021 at 8:14 AM, pnut said:

Could you line it with insulating firebrick like Morgan Thermal Ceramics K-26 IFB?  That way you could change out any portion that might become damaged a little easier.

That was discussed, but from my understanding the firebrick would deteriorate faster than the refractory. I'm open to being educated if that isn't the case. Thanks for the input pnut.

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Either way, the ash pan lining is a consumable. As pnut notes, bricks are a lot easier to replace, especially if they're bedded down in a layer of sand and ash. Which would you rather: pry out a brick or two and replace it, or have to chisel out the entire lining and replace the whole thing every time one part gets damaged?

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Seems to me that this issue would have occurred before; is there a way to research what has been used previously? Have you talked with the folks at the Cumbres Toltec Railroad?

I was reading the BBC and one of their historic train issues was the closing down of UK coal mines for "Climate Change"; so they are looking at having to import much dirtier coal from Europe and having the shipping contribute to the carbon cost as well.

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It depends on the type of brick and the amount of thermocycling they'll be subjected to, and the temperature they'll be reaching as to how fast they degrade. Hard firebrick is pretty tough but doesn't insulate well. The newer soft insulating firebrick is much tougher than it used to be but I've not had any first hand experience with them. I build forges all the time that can burn steel but only have a couple inches of clay I dig out of the ground  sperating that fire from the wood box it's in. 

I think I'd try hard firebrick on top of a layer of maybe an inch of clay. They make split firebrick. 

How often does the firebox cool to ambient temperature? 

Pnut

EDIT: As an afterthought. Will the coal in the firebox be creating clinker like in a forge or will it not be reaching a high enough temperature for that? 

 

 

Edited by pnut
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I'm not sure yet of the amount of thermocycling involved. When we are operational it will run every weekend, so will probably maintain temp for steam pressure over the weekend then cool down during the week. It definitely does get hot enough to create clinker, however the quality of the coal we use reduces how much I've encountered. This engine hasn't run since about '67 and this is the first engine that I have been a part of working on so I am learning as I go. I am unsure of the gauge of the ashpan currently. I'm in contact with individuals who run locomotives, but not with anyone that has done the conversion before so it is a bit of an experiment for us determining the extent of the changes that need to be made. When we decided to roll with coal we had a committed free source of coal, however with the political winds being what they are, we have access to coal considering the area with live in but the cost has definitely gone up considerably above "free". Fire brick usage is definitely doable I'm just glad to have this discussion with folks who are familiar with the products.

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A couple thoughts here. I got a look at Engine 557 while it was largely disassembled and being restored. They had the back off the boiler and the ash pan was relatively thick, maybe 1/4", maybe even cast. I couldn't tell and wasn't looking for that detail. You might be able to contact the organization, I'm not familiar with progress, etc. even though I drove past it at least twice a day. 

https://www.alaskarailroad.com/sites/default/files/akrr_pdfs/2012_08_14_Rls_557_Trnsport.pdf#:~:text=steam locomotive for eventual return to service on,facility%2C formerly known as the Kenai Supply Building.

If I had to wing it, I'd just use hard fire brick or pack the pan with a couple inches of damp clayey soil. Insulation isn't really a factor. Preventing warpage is a matter of differential heating, a layer of clay or fire brick will evenly distribute heat. Just like claying a forge pan, sheet steel warps, cast iron cracks if it isn't clayed. 

The coal bed should be receiving air up through the fire grate so the blast is passing over the ash pan and should be cooling it. 

An acquaintance, some years ago was involved in relining the coal boiler in the interior and dropped off a bunch of fire brick from the furnace. They're nothing fancy, just oversized hard fire brick. IIRC about 2"+ thick, 9-10" wide and 18-20" long. That power plant is fired with powdered coal that is blown into the furnace chamber in a blast of air and burned like a gas burner. The only time they shut it down is to reline it and they have to calculate how much of the liner will be damaged cooling down and reheating so they can compensate.

So, that's my reasoning for hard fire brick or a rammed clay liner. Say 2-3pts sand to 1pt clay and just moist enough you can pack it hard with hammers. Probably a good idea to strike some expansion grooves to control checking. It WILL check.

Frosty The Lucky.

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