carbon chunk

[Scott Hegan]

I fished this out of my burner head yesterday. It's obviously carbon, and I've heard that my eclipse head is notorious for building carbon up, but still, this thing is big.
What can I do to minimize the buildup?
Does the new recuperator have anything to do with the buildup?
Is this dangerous?
Scott

[John Teeter]

:eek:

so...this idea is car technology...but the way to reduce carbon build up in the combustion chamber in cars...is liquid water injection. Basically steam cleans the combustion chamber of the engine.

would you need to do it continously? maybe. if you did it once a week as a preventative maintenance....would it work? maybe.

basic setup would cost about 100 bucks. Lemme know if you want more details

john

[Antiny Genet]

I have a recuprated eclipse burner I have a small cool air line going into the back of the viewing window this is ment to help stop carbon build up.From there it's all up to the fine tuning.

[Pete VanderLaan]

It looks more like part of the burner to me.

[Scott Hegan]

it also looks like some glass I've seen, but it isn't.
the burner is in fine condition, it's got a high temp stainless steel nozzle.
is it likely that I'm running the furnace rich?

[Hugh Jenkins]

I have seen clinkers from the beginning of dealing with recuperators of every kind. It is part of delivering raw fuel into a very hot burner port. Since the air and gas are kept separate, there is a very fuel rich core in the injection zone of the burner. If the gas inlet gets hot enough the fuel will "crack" without oxygen and free carbon will build up on any surface it hits. There are two solutions, one is to not have the gas line come in surrounded by hot air. That requires a very different burner design. The second is to add a small amount of cool air in the fuel train. That makes the flow a little higher and cooler and gives a small amount of oxygen to begin combustion in the center of the fuel cloud.

It sounds like Antiny's solution is similar and specific to the Eclipse.

This has been part of the challenge of recuperators. If they are too hot, clinkers can be formed. But we want as much heat as the system can handle. Eclipse limits the temp recommendation for their burners. Charlie Correll designed his for excess air to run them cooler. You may be delivering the air too hot for the design of the burner. Also anything that does not deliver the gas right on center in the burner throat can be a problem.

If you want to get maximum heat, most likely a very different design will be needed.

[TC Robertson]

I recognize that lump! I called it furnace coal, and it built up in my Eclipse when I went to propane from nat gas. Too big a burner running at too slow after melting seems to cause it. A smaller burner, 400k, and a minumun air setting that isn't too low should help. We used to clean it out with a curved steel rod that you could get to the burner face from the door. It diverted the flame once in a charge and fried the burner block area. Good Luck, Later, TC:eek:

[Richard Huntrods]

I did my Chem. Eng. Thesis on a very related topic - Coke formation in a quench cooler (doing Ethylene pyrolysis).

After all the maths and simulations, coke formation is really a form of condensation. Flow velocity and temperature drop are the key parameters affecting coking rate.

Anything that interferes with the flow through the burner will increase the rate of coke deposition. Things like a sharp pipe bend right before the burner head or any baffle or manifold in the burner.

If you can arrange things so you have a straight section of pipe feeding into the burner head (say 12") that would help.

Any serious temperature drop can also trigger more coke formation. For example, a bare pipe just before the burner head will cause increased coke formation.

If you have bare pipe between the recuperator and the burner, try to insulate the pipe with frax (all the bare pipe - as close as possible to the burner head) and that should alsoreduce the coking rate.

In the end though, you may only be able to reduce the rate of coke formation, not stop it completely.

Regular maintenance then becomes your friend.

Cheers,

-Richard

[Kraig Richard]

Grown this substance previously in experemental platforms. More then likely....Your cracking your fuel. Less gas nozzle ( shorter gas tube) in the hot airstream, will reduce this effect. So will diluting the hot air with some cold air at the nozzle. bringing in the heated air as a secondary stream also stops growing carbon stalagtites.

[Antiny Genet]

When i melt i open my air valve fully and then open up the the gas untill i get the smallest hint of of a flame comeing out the top of the recuprator when furnace increases in tempture I have to keep notching gas down and again when its at the set point other wise the furnces in hevey reduction.After last charge and back up at set point I turn down both gas and air a good wack but enough to maintain set point this take a little bit of time to get it point were i like it ,working in low light helps.
I did have cabon build up with my new furnace at working tempture this was fixed by adjusting the low pressure bypass on the zero pressure regluator to its minimum setting.
I hope your melts are gong well and you have enough info to resolve you problem.

[Scott Hegan]

my incoming airstream is only about 200c at the burner. is this really hot enough to crack the fuel?
Hugh: saw pablo at the show. very excited about whats happening. is there any chance you're going to give a lecture at the gas conference? if so I'd love to attend.
Steve: are you still giving the class this summer and where do I sign up?

[Hugh Jenkins]

Scott, glad to hear some indirect news from Pablo. So far, I've had to figure no news is good news. I am waiting to hear an actual fuel use rate or at least final pressure settings.

I will not be giving a talk at GAS this year, but I will be there. Charlie Correll will be part a session that I think will be on comparison of energy sources and costs.

Back to clinkers. 200 degrees will not crack fuel, but it could accelerate it in the burner port. I had more clinker problems with "warm" recuperation than I now have with high temperature recuperation.

[Steve Stadelman]

Originally posted by Scott Hegan
my incoming airstream is only about 200c at the burner. is this really hot enough to crack the fuel?
Hugh: saw pablo at the show. very excited about whats happening. is there any chance you're going to give a lecture at the gas conference? if so I'd love to attend.
Steve: are you still giving the class this summer and where do I sign up?

YES, class on, $750.00 down to pob 453 forest grove ore 97116, $750 due when you show, see sticky thread at top for dates.

[Wes Hunting]

Scott,
Check out the expense of powder coating those puppies, this could be a blessing in disguise. It's totally organic, like free-range lettuce.


Dude...:thumb:

[Kraig Richard]

Originally posted by Wes Hunting
Scott,
Check out the expense of powder coating those puppies, this could be a blessing in disguise. It's totally organic, like free-range lettuce.


Dude...:thumb:

Wes Not sure if you meant that carbon chunk was organic or the powder paint. I powder coat parts at least once a week. ... Usually Biker Black :)

Depending on which color, labels from DuPont and other powder companies do not show powders used in coating are organic. Their ingrediants list read nearly as scary as any batch formula.

[Charlie Correll]

Yes, it is catalytic cracking, the hot air strips off hydrogen from the gas molecule before it has a chance to oxidize with the air. Propane is worse than natural gas. Propane is C3H8, natural is CH4. The carbon-carbon bonds in propane are harder to break than carbon-hydrogen bonds, so propane leaves more clinkers. But this is a MIXING problem. The thermjet mixing winds up with a whirling outer donut of air hugging the burner throat walls, leaving the gas in the center. The gas heats up from the preheated air, and a tiny fraction of it cracks, leaving the deposit. Bad. My nozzle mix burner has a better mixing system, leaving no dead gas volume to crack. The gas mixes with the air as soon as it's in the burner throat, and with proper air/gas proportion, leaves no clinkers at all. If your mixture is way rich, even on my burner, it will leave clinkers.

Having flames come up out of the top of the recuperator is a waste of ga$ and is very hard on the recuperator. Ideally, the mix should be set so that all the gas and air burns by the time it enters the exhaust port. Having combustion in the recuperator or coming out the door means that ga$ is burning that has no benefit to your melt. It's burning outside the furnace. It's like having too much air. The unburned gas cools down the flame and the furnace.

Adding cold air will help, but, hey, you are adding COLD air, that has to be heated up by the flame, thus costing you in efficiency.

[Scott Hegan]

is there any way to modify the burner nozzle (it's made of stainless) so that the mixture occurs faster and more completely? is there any way to cast or machine an aftermarket nozzle that will replace the flawed design? is there any component that could be designed and manufactured to the central fuel injection system inside the burner that would create a better mix? I realize that middle temp preheating is far from optimum, but it's a system I'm married to probably for the next ten years or so.

[Hugh Jenkins]

Scott, Eddie Bernard at Wet Dog has more experience with Thermjets and recuperators than I do. He is in the process of moving and might be overwhelmed for a while. But he finally gave up on them and is making a replacement burner that fits the same module.

[Charlie Correll]

The big burner throat with the small exit hole makes the problem worse, because it holds the hot gasses in the throat. The secondary air mix which doesn't hit the gas right away leaves unmixed gas getting hotter. But I don't know how to modify this burner.The literature says they will take about 700 degrees, but that seems to be iffy. Mine has a different principle of mixing, and probably would work on your furnace.

C

[Antiny Genet]

Originally posted by Charlie Correll

Having flames come up out of the top of the recuperator is a waste of ga$ and is very hard on the recuperator. Ideally, the mix should be set so that all the gas and air burns by the time it enters the exhaust port. Having combustion in the recuperator or coming out the door means that ga$ is burning that has no benefit to your melt. It's burning outside the furnace. It's like having too much air. The unburned gas cools down the flame and the furnace.

Adding cold air will help, but, hey, you are adding COLD air, that has to be heated up by the flame, thus costing you in efficiency. [/B]
I dose make sence that all combustion takes place inside the furnace my ecplipse burner is the first ever burner the i have brought for a furnace the thing that i like most about it is that it is very quite and as i live in the same building it is imporante to me. it burns with a lot of yellow in the flame and tend to work best in that mild redudction atomsphere. I the past i have built all my owne burners thay have all cranked with a blue flame but the have allways been noisy on the melt.
I am interested in your opion on how noisey you think your burner design is?
I am melting tonight so i will retuine my melting and back off the flame a bit and see how it goes maybe you can teach a old dog a new trick

[Charlie Correll]

The yellow flame in your burner is a characteristic of any nozzle mix burner. The gas and air are mixing in the burner throat and starting to burn immediately. The mixture is not as complete as in a premix system. The yellow you see is incandescent carbon, waiting to be oxidized. That oxidation takes place in the furnace chamber, closer to the glass, and moves heat more readily to the glass.

My burner is a bit louder than the Thermjet. I get more and better mixing action in the burner throat, and more turbulence which helps prevent the carbon buildup. What size is your thermjet? My 200 pound free standing pot furnace burns 186,000 BTU/hr on highest fire. The Thermjet 40 is for up to 400,000 BTU/hr, and would not be near capacity on my furnace, things would move slower in the burner throat, less mixing action, resulting in the carbon clinkers from preheated air.

I live upstairs from my shop and can barely hear my furnace on high fire. Actually, I like hearing it a little!

[Pete VanderLaan]

Originally posted by Antiny Genet
I dose make sence
**********

It sounds like you are coming down with a bad cold.

[Antiny Genet]

[ The yellow you see is incandescent carbon, waiting to be oxidized. That oxidation takes place in the furnace chamber, closer to the glass, and moves heat more readily to the glass.

That sounds quite positive I have thought that the yellow it was unused fuel and in the past focused my home built burners on blue flame this was influenced by my very first attempts at working with lead glass tubes the slightest hints of reduction or even a natural flame and the tube would go black.

What size is your thermjet?
From memory its a TJ040, a 400 000 btu burner

My 200 pound free standing pot furnace burns 186,000 BTU/hr on highest fire. The Thermjet 40 is for up to 400,000 BTU/hr, and would not be near capacity on my furnace, things would move slower in the burner throat, less mixing action, resulting in the carbon clinkers from preheated air.

So if I see it correctly from your perspective its better to have a smaller burner working hard out than a larger recuperated one cruising along producing clinkers

I have changed my melting a little i have turned down my cool air and my heated air up.
as for keeping the flame compleatly inside the furnace as soon as my tinyest hint of a gost of a flame disapairs the furnave starts to loose temperture.
I am melting again tonight so i am still working on the fine tuining at set point after large charge.

[Antiny Genet]

Originally posted by Pete VanderLaan
**********

It sounds like you are coming down with a bad cold.

Almost i am a few chapters over, Dyslexic so written communication is hard work.

[Charlie Correll]

"So if I see it correctly from your perspective its better to have a smaller burner working hard out than a larger recuperated one cruising along producing clinkers"

The properly sized burner, with recuperation, will produce fewer or no clinkers. The bigger burner is quieter because it's nowhere near capacity at high fire. The turbulence is better mixing and more noise, unfortunately. Back in the 70's I used sticktite nozzles on undersized burners, and it was LOUD. Now, my exhaust fans are louder than my furnace, except on high fire. It ain't all that loud.


"I am melting again tonight so i am still working on the fine tuining at set point after large charge."

How did it go?

[Antiny Genet]

[


"I am melting again tonight so i am still working on the fine tuining at set point after large charge."

How did it go? [/B][/QUOTE]

Bolwing then melting over night then blowing the next day
i am usely read for bed after the last charge it takes a while for all that gear hanging off the side quite some time to settle down and stop makeing small adjustments.On my last melt at some point I woke stagered out and turned the gas down this snuffed out my little gost of a flame and still maintainted my set point.

How do you cope with your electronics make suttle adjustments ?

I have made the odd noisey burner a few rumblers and one that whisteled and was painfull to be around.

I find that the smaller the combustion space in my gloey holes the more noise thay want to make, my largest16in GH is almost silent a 9in GH with a highend kind of rumble Both of those have home built ribbon burners and a 4in GH with a inherted Nu-way burner its small and fits in the palm of my hand I can tell it wants to roar but operates on the smallest movemt opening the needle valve for the gas and 1/2 a turn of a gate valve for air.
I would like to put a recuprator on this some time soon I have the first recuprator i built its a bunch of heavy walled 90 degree elbows welded togther to make a helex that i stuck in side a retired 9 in glory hole I dont think its a grate recuprator but im sure I could install it in less that a day and runn it in till some thing brakes my guess that clinkering up would be the first problem to show up the bottled LPG the i get supplyed with is designed for automotve use and has waxes in it for valve luberication i dont think this helps retard clinkers.
Do you have any thoughts on this gloryhole modification ?

[Hugh Jenkins]

Originally posted by Antiny Genet

"the bottled LPG the i get supplyed with is designed for automotve use and has waxes in it for valve luberication i dont think this helps retard clinkers."
______________________


I learn something new every day. I would suspect that waxes or oil might make a difference. However, with a glory hole, you turn off every day so the build up, if any would be burned during cool down. I also haven't ever had clinkers unless there is considerable reduction, at least locally in the flame. You would not find that to be a good GH heating flame and would most likely adjust the air before a problem occurred.

The only propane engine I have experience with, is my generator, and uses the evaporated gas, not liquid carburation. That would leave the wax behind somewhere in the system.

[Charlie Correll]

"How do you cope with your electronics make suttle adjustments ?

The thing that makes it's own adjustments on my system in the proportionator valve. When it tweaks out, I tweak it back in. Every few weeks. If you have to tweak when the furnace goes from high to low, or low to high, then the overall adjustment is out of whack. I've got a paper on my websites that goes through forced air/forced gas unit adjustments, all the way from a two valve glory hole to a full auto system on a furnace.

correllglassstudio.com >> Controls and safeties>> Partlow Furnace Control Systems >> Control of Burner systems


"I have made the odd noisey burner a few rumblers and one that whisteled and was painfull to be around."

Me, too. And they are worse on small glory holes. It's the burner, not the glory hole. The whisper burners I was making had a 1/4" holes expanding to 5/16 as it got to the front, to slow the speed down and keep the flame on the burner. I finally changed the 1/4" to 1/8" and the problem just went away.

"I would like to put a recuprator on this some time soon"

One of my first recuperators back in '81 was two stainless pipes two feet long stuck in the chimney. It worked GREAT! for two weeks at which time it burned out. I think that may happen to your pipe fittings, but you will learn a lot.