Ribbon Burners?

[Frosty]

I have a request from a local bladesmith who wants to make a heat treat oven and would like to use a ribbon burner. In spite of how many burners I've built I've never build a ribbon burner and need some general rules of thumb such as:

Number and dia of the burner holes per sq/in. and pattern if there is one.

Size of the plenum per length of burner. He wants a pretty long forge, upwards of 4 1/2' so I think there will need to be a substantial plenum to maintain an even pressure to the burner holes.

How much blower? Placement of the blower output in the plenum?

And anything else we might need to know.

Thanks,

Frosty

[Charlotte]

Sorry that I cann't find the Hammers blow issue, but a couple of years ago they showed a step by step build of a top down ribbon burner.

Some one here mentioned that they had built one.

I'll look some more tomorrow.

PS. Couldn't go to sleep until I found it. Winter Issue 2006 Hammer's Blow. Article by John Emmerling "Building a Ribbon Burner"

His burner was 3x3x3/16 x 10 long 2 " pipe With a baffel welded at the pleneum entrance. 3 rows of air holes cast in place with crayola crayons. Holes about an inch apart two rows of 9 with one row of 8 in between.

He used Mizzou or HPV-ESX castable (comes in 50 lb bags) He used one of the centaur forge electric blowers that has a Baldor motor. He used a 1/16 inch orifice for propane and thought normal house hold gas and 1/4" would be adequate. Gas introduction should be 9 times the pipe diameter or 18 " for natural gas and maybe shorter for propane.

Edited May 15, 2009 by Charlotte
add info

[Glenn]

Frosty, use the search engine, it is your friend. (grin)

Ribbon Burner Forge (with photos)

[mike-hr]

I measured my burner this morning, same specs that Charlotte said. I've been playing with different size Mig tips for the gas orifice, Currently I'm running a tip drilled to .073 inch. I've changed the blower out for a quieter one, and then changed pulley sizes to get it to run faster. Each time I got more air to blow, I could use a bigger gas tip. My burner, at 10 inches long, has smaller flame tips at the holes on the end. McraigL did some thinking on it and when he did his, he took a holesaw cut-out that matched the inside diameter of the air feed pipe, did some slitting and twisting, and made a nifty propeller shaped disc that got welded between the gas inlet and the burner box. He's getting really good air/gas mix and gets consistant flame in all the holes. I'm still quite happy with the forge, except that it pumps out a lot of CO during start-up, so I have to open the big door for 15-20 minutes. That becomes an issue on cold winter mornings, but the shop warms back up fast when I close the door. Once it's at running temp and tuned neutral, the CO meter reads zero all day.
Thinking about your 4-1/2 foot long forge, I don't know if you could go longer burner and less rows and still get fuel/air all the way to the ends. A long thin burner may be more prone to cracking over time. I don't think you need the whole length covered with burner, mine heats the forge very even throughout , but 4-1/2 feet is a long tube.

[Charlotte]

Carlise Manufactruing recomends, for their cast iron ribbon burners," The recommended premix burner pressure is 1 1/4” W.C. When
using a premix system at a pressure higher than 1 1/4” W.C., a
restriction orifice can be installed in the feed inlet of the burner
to maintain the correct pressure."

[Frosty]

Thanks guys, this'll give us a departure point with some hard numbers.

Search engine? As in look it up myowndarnedself? Golly gosh Glenn you're starting to sound just like Dad.

Thanks again.

Frosty

[Charlotte]

Frosty, btw the Carlise folks seem to max their individual burner lengths to something on the order of 18". ( If i remember the info correctly) I'd guess there is some sort of either manufacturing, practical, or marketing limit there. It appears that after that they use multiple units. This is just my understanding of their propaganda, and I could be misreading.

For blowers I'd guess you will need something on the order of the blowers sold for Johnson forges.

The same equations apply for btu, propane consumtion and air consumption as any other burner.

I'd guess two manifolds feeding four burners will get there. two right two left and about the size of the single burners already shown.

[Frosty]

Thanks Charlotte, that's pretty much what I'm thinking.

I've heard of and one time saw pics of a ribbon burner in a commercial furnace that had to be 20' long but who knows how many separate units were behind the wall.

My thought was to calculate the area of each burner hole and calculate how many it takes for the desired volume. Then determine a range of blower output and pressure. Add propane to taste.

I'm thinking he's probably going to end up with a manifold feeding three or four zones in a burner this size regardless. Might as well just make 3-4 burners. I've already suggested manifolding a number of small burner nozzles rather than a ribbon this size but . . .

I'm waiting for him to get back to me with some dimensions other than length and am trying to convince him to sub to IFI. We'll see.

Thanks,

Frosty

[Charlotte]

Hope I what I gave you helps. My first paying job was running heat treating furnaces for a major steel company. We used high pressure natural gas with open burner ports for most work.

High alloy furnaces were positive pressure units with very precise control. But not ribbon units.
This was back in the sixities when much of the decison making was done by the operator following a temperature profile drawn by the engineer.

[Frosty]

It's all information and it's all useful. When you're stepping into unknown territory everything you can learn ahead of time is useful even if not for what you want to do.

Frosty

[prburner]

More information here Pine Ridge Burners - Home Page

Will be glad to answer questions.

Regards, Tom

[Charlotte]

More information here Pine Ridge Burners - Home Page

Will be glad to answer questions.

Regards, Tom

Looks like a good deal. The added feature of "metering tubes" is a real bonus. Thinking about the hassel factory of building it your self the price is reasonable. With the availability of safety controls from the same supplier I belive that is solves most problems.

One question that I have is " What happens when the forge is at sustained welding heat? I've had metal inlets melt from reflected heat on a number of occasions. They were well back in refactory ports with an air gap all around. Edited May 16, 2009 by Charlotte
spelling

[Glenn]

Frosty, search engine as in we may not remember the fine points that were discussed previously.

[Frosty]

More information here Pine Ridge Burners - Home Page

Will be glad to answer questions.

Regards, Tom

Welcome aboard Tom, glad to have you.

Talk about timely. Did someone tip you to my questions or was your joining us a just another serendipitous event? I'm tickled either way. . .

I'll pass this along to the fellow wanting to build one. I'll be spending some time reading through your site so I can ask intelligent questions. I'm becoming more intrigued the more I find out.

If you'll click "User CP" at the top of the page and edit your profile to show your location it can make a big difference. IFI is represented by more than 50 countries and a lot of info is location specific.

Thank you Tom,

Frosty

[Fe-Wood]

I saw those Pine Ridge burners at the CBA conferance. They look good. Didn't seem to go through tons of fuel either. He had them on all day for two days. Impresive!
Seems to me you would want to run them in series. As stated before, even heat will be an issue on the ends.

I will be interested to see how you guys work this out.

[prburner]

Thanks for the welcome Frosty. Actually, I met James Johnson (Anyang USA) at the CBA Conference a few weeks back. He sugested I join your group. Figured I'd lurk until a ribbon burner question came up - didn' take long.

To answer some of your original questions about "rules of thumb" :

As you figured, the number of and placement of orifice holes is important. Too few holes and the burner block will not keep itself cool and you will have backburning problems at high temperatures. Too many holes and the structure of the block will be weakened. Either way you will have a short burner life. I use a 13 to 1 ratio. That is, the area of the burner face that is solid is 13 times the area that is orifice. Example : one 5/16" orifice for every 1 square inch of burner face.

As to placement of the blower output in the plenum. This, of course, becomes more important as plenum size increases. The pipe you see entering the plenum on my burners runs the entire length of the box. It is perforated in such a way as to distribute the fuel/air mix along the length of the burner, evenly pressurize the plenum, and at the same time create a vortex inside the plenum to further mix the fuel and air. Even with a properly baffled delivery system, if your blower output is in the 1" to 3" WC pressure range you are limited to a maximum plenum size of around 180 cubic inches. So yes, your friend will need more than one burner.

Charlotte,

A properly designed and installed ribbon burner uses the flow of fuel and air to defend itself from the heat of the forge. All metal parts should remain cool to the touch even after hours of operation.

Regards, Tom

[Frosty]

Well, it is a bit of a coincidence after all. Cool, I love it when that happens.

Thanks, the rules of thumb will flatten the learning curve quite a bit, especially the holes : solid block ratio.

I was already planning on making sure the burner holes exceeded the area of the supply pipe to minimize restriction. Setting a baffle to induce a vortex is another good tip. I hadn't considered that at all. I don't know if it's even legal for a commercial appliance maker but I like introducing the gas into the blower's impeller to enhance mixing. If we can make it work well enough with naturally aspirated, inducers, a vortex in the plenum will really improve things.

Making multiples is a lot easier than trying to make one large unit. It's helpful to have a Pro saying the same thing.

Thanks again.

Frosty

[NeatGuy]

I make a very easy to make ribon burner. I have built several as shown in the Hammers Blow article and have found it to have many design flaws. I will post some pictures of the one I started yesterday. It takes about 2 hours to assemble no cast refractory.

Here is an early version which works well but I would recomend the new version which I will post some pictures soon.



brad

Edited May 17, 2009 by NeatGuy

[Charlotte]

.....Charlotte,

A properly designed and installed ribbon burner uses the flow of fuel and air to defend itself from the heat of the forge. All metal parts should remain cool to the touch even after hours of operation.

Regards, Tom

Thanks Tom, I rather thought that was the answer. One more question, have you thought about or looked at creating a chip forge type of set up using your burner. Specifically I've been thinking about a side draft set up.

[prburner]

Frosty,

I can't agree with your idea of having the outflow of the burner exceed the supply pipe. It takes a certain amount of backpressure to evenly pressurize the plenum to the point that all the delivery orifices will burn evenly. This required backpressure is also the
reason that a naturally aspirated system will not give satisfactory results. The keys to an efficient ribbon burner are an evenly pressurized plenum and accurate metering of the fuel/air mix into the delivery orifices. If you study the flame characteristics of
most homemade burners and compare them to the photo on my site you will see what I mean.


Charlotte,

I had never seen a chip forge in action until the CBA Conference last month. I think a ribbon burner would work well for that application and have been rolling some ideas around in my head. I agree, side draft will be the first thing I will try. Someone bought a burner from me at the Conference to use in building a chip forge. He said he would keep me informed as to his progress. I will pass any info along.


Brad,

Using the expanded metal as a diffuser is ingenious. Looking forward to seeing your new version.


Regards, Tom

[NeatGuy]

Here are two pictures of a burner that I have been working on. One advantage to this method of construction is: one can easily replace the nozzel with makes it easy to experiment.



I also have a pdf file with dimensioned plans but am not sure how I can post this.

brad

[prburner]

Brad,

I'm guessing that the nozzel is an insulating fire brick (IFB) with holes drilled in it ? How do you seal it to the steel shell to prevent leakage? Are you still using the expanded metal baffle?

Regards, Tom

[Charlotte]

Tom it looks like its tapered to me. A little mortar and some inswool would make a sort of seal. With enough pressure behind a little leak might not make any real difference.

[NeatGuy]

Yes it is a high temp fire brick with holes drilled in it. If could post the pdf it would explain alot. I use a high temprature sealant which seems to work well and so far seems to last. I believe that a skim of refractory mortar would also work. I changed the diffuser to sheet metal with slots cut in it but I believe that the expanded metal works better. Most of my research with this burner has been to simplify and improve on the construction.

Since you, prburner, have done more of the science end of this burner, I was wondering how tapered holes would perform.

brad

[Frosty]

Brad, you can attach a .PDF file just like a .JPG file, from the manage attachments menu. Just select the PDF file and upload it.

Tom:

One factor of getting naturally aspirated burners to work properly is balancing back pressure to output. With every branching, bend, obstruction, etc. you should increase the cross section to maintain optimum output.

It isn't to eliminate back pressure but manage it. Introducing an induction device's output into a plenum will cause a lot of turbulence as well as back pressure. If the back pressure raises above a certain threshold it will inhibit induction which will be less able to overcome the back pressure and further reduce induction. It happens on a geometric scale and quickly.

On the other hand ejector type induction devices can be made to develop very strong vacuum and pretty respectable output pressures, they just need to be designed for it.

I'm not actually recommending a person spend a lot of time and effort trying to design an inducer where a gun works so well. Unless you like to tinker of course.

Thanks again for the great info.

Frosty