Another keg furnace

I am not sure I understand the question exactly, but I like the squared off support you added.

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Hi pat.
I am wondering if I can replace the 2 inch water pipe that has an O.D. of 2-3/8 inch that I now use in the burner with a somewhat smaller diameter piece of tubing?
This would give me a bit more refractory above the burner tube where it enters the furnace.
It is a bit thin now at ½ to 3/4 inch thick.
The other part of the question is how would I go about curing the refractory in the new squared off support? I could just put the whole bottom of the furnace in a quick oven built from a cut off 55 gallon drum and heat it up in a good hot fan assisted wood fire.
I am using a siphon nozzle and plan on making a quick release type hanger so the burner assembly can be easily be removed.

Joe

 

I prefer a burner tube that is a little over 2" diameter, but that is my personal preference.
I don't think you need a lot of refractory around the burner tube.
If you set it up correctly (don't extend the burner tube into the furnace, but rather stop short of the furnace interior), then basically the tube runs almost cool to the touch, so the refractory is more of just a method of sealing the burner tube to the furnace, so you don't have combustion air blowing back past the burner tube/furnace joint.

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I could go with the original 2 inch water pipe. I have one ready to go. I was just thinking if I could drop the diameter a bit . I could maintain a more uniform thicker lining around the tube.
I hope to use a small blower for combustion air and a small hobby low pressure compressor to supply air to the nozzle. The compressor was designed for small paint guns and air brushes.
The fuel will be supplied by an automotive fuel pump. It will have a regulated pressure from 0 to 10 Lb.

Good night! Back tomorrow.
Joe

 

So the question becomes. With the temperature only being very high an inch +/- from the burn chamber. With what do you fill the box? Refractory followed by a cement that is chemical set not thermal set with a tube through it to hold the burner? All refractory? Refractory followed by wool or just a small amount of refractory to form a seal around where the tube enters the chamber and use the empty portion just to help support the burner?


Joe

 

I personally (opinions will differ on this no doubt) would fill the box with refractory.
I would wrap the burner tube with plastic wrap, and perhaps grease it a bit under the plastic (burner tubes are notoriously difficult to pull back out of the refractory, but the plastic should work).

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How would you then go about curing the refractory? I could build a quick and dirty wood oven or possibly bury that part in charcoal in a grill with a fan pointed at it.
What would you do?
Joe

 

I would cure the refractory like I cure all my refractory.
I use a propane burner, and start with it in the tuyere and on low.
I let the temperature of the furnace rise over about an hour, and increase the burner output about every 15 minutes.

I get the furnace hot enough to begin driving off any moisture in the refractory, which is a light steam that comes out of the refractory.
You do not want to get the refractory too hot too fast, else you will flash the water into steam and crack/explode the refractory.

One the steaming gets to be minimal, which should be after about an hour, then continue to turn the burner up until it is at its maximum.
If you turn the burner up and get heavy steaming, turn it back down for a while.
Once the steaming stops, I generally change to an oil burner, and start it at about 1/2 output.
If no additional steaming happens, then I go to 3/4 output, and again if no steaming happens then full output.

I run the oil burner at full output for perhaps 10 minutes, and if there is no more steaming, then you are done, and the refractory is dry.

That is my method.
Others have some elaborate rituals and obsess with light bulbs and all sorts of stuff.
I ignore the rituals and do it my way.
For iron work, the refractory is going to crack no matter what method you use for dryout, so I use my method which uses minimal time and fuel, and touch up any cracks with Plastic A.

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Ok sounds good. I was thinking that a total filling with refractory might be the best way to go. I just have not had enough experience with the stuff to know if it would hold together if not adequately cured through with it being on he outside so far from the burn chambers heat. It will be inside the S.S. box portion.
For now I am out of refractory and will be pickling some up in a couple of weeks. For this and some other projects I plan on buying a 50Lb. bag. I also want some Satanite for patching and repairs. With a limited shelf life. Is this something that I would want to buy a 50 Lb. Bag of? Or would it be best to pay 2x the price a pound and buy 10 Lb. At a time?
Joe

 

What are these pictures of? I'm confused.

My experience is that Satanite does not have a shelf life. I routinely use some which has been wet and dried. I put it back in water and it makes good mud again. By dried I mean naturally dried, not fired.

 

The pictures in post 164 are that of a SS corner add to the bottom part of a keg furnace to help with the burner placement and retention. This is the part where I would be looking at refractory. Or at least within 2 inches of the burn chamber. Wool has not been considered at this time, This furnace will not be moved so mass is not a problem. The other use for the castibel refractory if for piths. At this time I have 0!
In post 153 there is a picture of the furnace in early development that shows how the bottom separates allowing you to see where the S.S. box like part will be in reference to the frame.
The Satanite is for used for furnace maintenance. Thank you for letting me know that Satanite had no or at least a very long shelf life.
I will use the 50 Lb of refractory quickly. Satanite not nearly as fast. It is under ½ if I but it in the larger bags and pick it up.
Joe

 

Thanks, I seem to remember you were building a lift off furnace now. I had forgotten.

I believe in drying out refractory to the manufacturer's recommendations as closely as I can.

Satanite goes on thin. I tried putting 1/2" in the floor of my furnace and it would not dry, shank, and curled up on the edges. I pulled it out and almost threw it away. Found out it was exactly like dried mud, and reconstitutes like dried mud. I'm still using those dried chunks when I need Satanite.

 

This is the only picture I have of the barrel at this time showing very small cracks vertical up and down its length. They are caused by using fire brick that are do not have a high enough temperature rating for this application, Covered by a thin wash of refractory. I think a couple of coats of Satanite should increase the insulation enough to protect the bricks.
I do not want any more build up than is needed. The furnace bore is now 10 inches. This does not leave any room for anything over a number 10 crucible while leaving enough air room. I hope to get a bit more efficiency of early fuel air mix and burn when burning oil by the way the burn chamber was designed. It is made like it was molded around an inner tube with the center filed in. The diameter of the chamber is 12 inches at its center maximum point and 10 inches at its edge where it dumps into the barrel.
Joe

 

Hi Kelly
The Satanite cure on the barrel inside for me will not be the problem as I will be painting it on as thin as practical, cure and repeat a minimal amount. Trying not reduce the diameter any more than I must while doing any repairs.
The part I am wondering about is around the tuyere. I want to fill in the box around the burner.
I now have a burner that is made of 2 inch water pipe. It leaves only around ½ inch of refractory above at the top rim above the burner. A 2 inch water pipe is 2 -3/8 O.D.
I would like to replace the 2-3/8 O.D. water pipe of the burner with 2 inch O.D. thin waled tubing. This would give me an extra 3/8 inch to build up refractory over the top where it is thin.
It would also restrict the I.D. of the tube causing a restriction in the air and an increase in velocity. Something that would not be good. I think I could make up for the loses of I.D. By improving the way the spray nozzle is held in the tube.
I have considered welding a small tube in the box portion at the tuyere to help hold the burner and just packing the box with wool although I would like this part filed with refractory. If I can find a way to cure it.
Joe

 

You can melt a lot of metal through a 1-1/2" pipe. Don't sweat the combustion air velocity, it all burns in the furnace anyway.

 

I am a poster child for refractory abuse.
Plastc A is your friend if you are in a hurry.

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Velocity causing cold spots on the impingement side of the furnace has been a concern.
With the burn chamber being convex and shaped much like an inner tube. I hope to get away from this. I have a hope although it might be just that and not a reality. By having the burn chamber wider than the barrel. This will cause the flame to swirl around the bottom of the chamber and pith delaying it from climbing up the sides of the furnace a bit longer and keeping the hot gases where I want them longer.
I have not came to a conclusion as to the final diameter of the burner tube but if I go with 2 inch O.D. thin wall exhaust tubing it will give ample refractory thickens. The thoughts of using a 2 inch O.D. tube welded into the S.S. add on and potted in refractory as a sleeve for the burner is somewhat appealing. If I use this method and use thin wall 1- 3/4 O.D. tubing such as exhaust pipe. I could easily fit the 1-3/4 removable burner inside this sleeve.
Joe

 

I made it back out to the shop to work on the furnace a bit.
I had some cracking in the liner barrel and some damage to the lid that could become structural if not attended to. The tawnier -“ burn hole” was irregular shaped causing a rough transition where the fuel air mix end of the tawnier enters the furnace.
I had also recently added a squar box like extension to the tawnier.
There was a metal exhaust pipe fitting installed in this box with 2" ID. on the outside and 2.25" OD. on the other end going into the furnace. I flooded the box with 3000 degree refractory with the tube slightly protruding into the furnace. After air drying I smoothed in the transition where it goes into the furnace with Grefpatch 85. And then thinned the Grefpatch 85 down with water and coated the entire inside of the furnace.
This Grefpatch 85 is a bit expensive but it is suppose to be really something. It comes premixed with the consistency of a thick masonry mortar.
Now comes THE QUESTION OF THE PITH ?
What is every one using? I have 45 extra pounds of dense refractory at this time.
Do you prefer a solid mass or a hollow body? My furnace is convex around the burn chamber. I had considered making my piths convex to maximize burn chamber room while maintaining a circular air flow. What do you guys think?

It has become obvious that I wont have this one done by my set goal of the 4th of July... of last year or this one for that mater, but there is always the 4th 2020!

Joe

 

Solid plinth made out of Mizzou. Make a few of different heights if ya can. I used a cool whip container for mine. Has a nice shape and is very stable with a heavy pot of metal on it.

It's a Tuyere... pronounced two-yair

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