Burner Efficiency What to Buy or Build

[iron quake]

I’m going to be building a new forge with open ends with doors and a clear open side as well. The design will be somewhat like David Hammers Super C design but deeper and longer 5” high 9” deep and 24” long. I’ll be able to shut off burners when I need less working volume and reduce the volume with a movable back wall as well. I don’t forge weld so I don’t need that but I’d like that level of performance. I need this size and style to be able to forge furniture parts. I have a forge like this now but its too small and VERY inefficient. So I know what I want, now how to heat it is the question.

 

I’ve looked at burners by Reil, Frosty, Rex, Zoeller Devil Forge, and Hammers hybrid style. My question is has anyone quantified the energy efficiency of these burners. The website of Devil Forge claims their hybrid burners are 30% more efficient than their standard burners. What about the rest of these other burners? This forge is going to consume a lot of fuel, so efficiency is very important to me.

 

Thanks in advance for your input and suggestions.

[EricJergensen]

I doubt those claimed numbers have been rigorously established. Do they define their test setup? They're basically saying that their standard burner burns 77% less of the propane going into it.

 

Efficiency comes down to this: do you burn all the propane?

 

For naturally aspirated burners, it basically comes down to mixing efficiency. If you get "complete" mixing of the optimal ratio of air and propane, you've gotten all the efficiency you can get. (You've got to get that mixture at the nozzle so the propane can burn before it gets too diffuse to combust. It won't burn well later, when spread out with all the waste gasses.) I doubt any of those burners you listed really is 30% more efficient than the "worst" burner at their respective optimal fuel consumption. Most of the difference probably comes down to operating range: the "best" ones can operate near their peak efficiency over a wider range of fuel consumption.

 

Note: most people don't try to run burners at peak efficiency. They want a slight excess of propane to cut down on excess O2, so they don't scale the metal as much. If you hit 100% efficiency, there will be no dragon's breath.

 

On the other hand, roughly 80% of the air you use in combustion is inert (almost all of that 80% is nitrogen). So, you do waste quite a bit of heat on bringing that up to forge temperature (and then lose it as exhaust). A recuperative forge uses exhaust gases to preheat the air (and usually propane as well) getting some of that lost heat back. That's not an option if your forge is very open. (And, you must use waste heat, I've seen designs that actually end up using forge heat instead of exhaust heat. That's a net efficiency loss.)

 

All that said, if you burn a lot of propane, you'll eventually make up the burner cost increase even if it's only a 10% improvement.

 

Also, you would get much more benefit from being as enclosed as possible (given the stock and enough opening that you don't end up with back-pressure on your burner).

[iron quake]

Thank you Eric for your response I guess this topic is of little interest on the forum or more likely no one else has any idea as to the efficiency of their design or anyone else's. 

 

Given as you say a small increase in performance could be of great value in fuel savings over time, any idea how to figure it out? I don’t have the means to purchase or build and test all of these, to make any determination on my own. I was hopeful someone else would have done that already. 

 

I find it peculiar that there is a lot of boasting about all these burners and how simple they are to build and CHEAP, with plumbing parts for $10, but no one seems to care about $100’s in fuel costs. 

[ThomasPowers]

Go with a blown burner---a lot more adjustability   All the pro's I know that do big work use blown burners

[Kenny O]

I have been trying to find the answer to your question as well. I have built a few Porter burners, very labor intensive I was going to build a frosty "T" burner because of its ease but I don't know the specs on consumption.

[iron quake]

I'm going to purchase a burner from Jim Fox at thermal Art Design. $85 nice looking burner and a good price. I'll land one in my old forge after I re-line and coat it and see how it acts. I have a nice little machine shop but at $85 I can't even think about making them. I spend enough time making power hammer and press tooling as it is. 

[Kenny O]

That is a fair price, I will do a web search. This is the last burner I made for a smelter.

 

 

[Frosty]

You're absolutely right, most of the guys talking about burner efficiency not only don't know what that means but haven't tested anything. I only report my observations and have built quite a few different types. Ron Reil is the one exception to this trend I know of, though Michael Porter may have tested as well. I'll ask him if you just MUST know. Ron not only is a retired science teacher he has the equipment on the shelf to do meaningful tests. I have to say he was NOT happy with the results but that's a different story.

 

When I say an ejector type induction device is around 30% more efficient than a lineal induction device I try to stress it's a more efficient inducer, not burner. Those are two different things.

 

It doesn't matter how you do it, if you properly mix 17.5 pts air to 1 pt propane it will produce 95,000 BTUs per gallon. The actual BTU rate is misfiled somewhere in my dented memory, there's a bit more to it than the rounded number and there is some variation in batches. Take it as a ball park figure for conversation sake or look it up.

 

What makes an ejector a better burner than a linear is the higher induction rate, it makes them much less vulnerable to breezes and back pressure hence it's more practical in a forge that isn't going to be in a sheltered environment. The increased induction efficiency is why ejectors are used to highway clean drains, pump bilges in a hurry etc. Truth is they suck better than they blow.

 

No matter what kind of burner, be it naturally aspirated or a gun (blown) it must be properly adjusted to your needs. If so, it doesn't make one whit of difference what kind it is you will get just so much heat per gallon of propane. If fuel economy is a major factor it may be worth the time to do some research into other fuels.

 

I believe virtually every flammable substance has hard info, from handling and transporting to flame chemistry as in fuel:air ratio, exhaust chemistry, total unit BTUs, BTUs per second/minute, absolute temperature, etc. There are gvt departments that research and publish this information for a number of reasons and it's public information. For a start you might ask the FD, they have to be able to access this info  quickly under stressful conditions, often with people's lives depending on them getting it right. If they won't tell you what you want to know they probably know where you can look.

 

Asking general questions expecting specific and scientific answers on a blacksmithing web site isn't going to be terribly satisfying. Very much of what we do is by guess and by gosh. For instance, I'm going to try this type X burner and see what happens. And a week later saying My forge is plenty hot but it sure went through that 100lbs of propane fast. I'll just write that down and give a Jimmy Pete's Hottsy burner a try and see.

 

Frosty The Lucky.

[EricJergensen]

Correction to the 1st paragraph in my previous post. I meant to say that 30% meant that the standard burner burned 77% of the propane that the hybrid burner did. That means that 23% of the propane that the hybrid would have burned is supposedly just wasted by the standard burner. My point is that this doesn't make sense. It seems implausible that any half-decent burner is throwing away 23% of the propane that some premium burner would burn.

 

It's not that we don't care, but it is super difficult and super expensive to set up the experiment. Even if I do set up something that allows me to test one burner vs another, that only tells me about those two specific instances of the burner. If I want to know something about whether brand X typically outperforms brand Y and by how much, I need a large random sample of each brand of burner. 30 would be a minimum. Then what about testing a range of outputs? In wind? Each individual experiment answers one very specific question, so it would take tons of individual experiments to get a good picture.

 

Or, perhaps all you want to do is know how your forge works. Well, that's easier. Build your forge. Buy a set of burners from several manufacturers. Install a set. Fiddle with it until it holds your forge at, say, 2400°F and then see how much propane it burns in a hour (doing absolutely nothing with the forge in a room carefully maintained at 78°F with no breezes and a constant level of O2). Now do the same for each of the other sets.

 

But, I think you'll find fairly minor differences. The real payback is in stopping heat loss. Thicker/better insulation. Better IR coat. (Frosty, I think, noted that the performance of a fresh coat of ITC-100 is much better than an old coat.) Better enclosure (maybe options to open it up at need, but keep it to the minimum exhaust size usually). Recuperative forge.

 

Or, make a natural gas powered blown burner. Much cheaper fuel per BTU.

 

To answer your question about calculating savings: assume some amount of consumption reduction and then just take that off of you're cost of propane. If you can save 5% in consumption (my intuition here is that's pretty big savings for one burner vs another) on 100lbs of propane, that's close to $5 each tank (about $1/lb so $100 per tank times .05). If you use 100lbs per week, 50 weeks a year: $250 per year. I suspect very few folk use anything like 100lbs a week every week. But, maybe somebody else can offer guidance here. I have yet to spend $100 on propane, total, since I usually use coal. 

[iron quake]

Thanks to all of you for your replies. I guess what I take from this is, its much more important on construction, insulation and coatings than the burners. I have an induction forge from Monster Metal and that saves a bunch on the propane but I can’t do large furniture parts with it.

[Frosty]

Eric: WOW! Anyone saying their burner burns more fuel than others, all things being equal is BSing. As you noted it doesn't make sense, it just ain't so. If your burner is wasting 23% of the propane your forge would have yellow dragon's breath a foot or two high out the doors.

 

While Ron was using pretty sophisticated test equipment in controlled conditions I THINK he finally realized how little it mattered. Heck, he didn't like the results in they didn't make sense to him but that was the result of how propane behaves, not the numbers.

 

What a person working at the forge needs to  know in reality is two fold. Does the burner and forge do the job? Is it efficient?

 

Trying to determine consumption rates by the cu/ft, gal, etc. is pretty . . . Just time how long it takes to run through a full tank a few times and average it. The environmental differences will cancel out. The arithmetic is easy. I typically get about 8hrs from a 40lb tank running two of my 3/4" burners at 5-9 psi. But that's an average and doesn't take into account the slight differences in propane's BTU per batch.

 

So, considering running two chambers on my forge is about 700 cu/in and open at one or both ends and 9psi will bring most all of it to welding heat on about 5lbs/hr. that'd be about 2.5lbs. using one burner in one section. AND I adjust my burners to run rich for a reducing atmosphere in my forge. You can see pics of my variable geometry forge burning in the gas forge section, it has a generous dragon's breath.

 

Insulation is good, a high zirconium kiln wash is even better, it's darned resistant to flux. but both is best. ITC-100 is out of my price range now, we buy Zircopax and kaolin clay and make our own kiln wash. If I said fresh ITC works better than old I misspoke or was misunderstood. It works a treat till it's worn off. Where a person really sees the difference is when you first fire a freshly washed forge compared to it's unwashed performance. Maybe I didn't say that well enough but the 2-3 year old wash on my forge still does just what it did when fresh.

 

All in all unless a guy is operating on a margin of a couple percent or running a factory sized forge almost any of the home built burners you see will work just fine if adjusted properly. The efficiency difference between a Porter type IV and a Porter type V is insignificant and Mike put a lot of effort into improving that version.

 

Iron Quake: Didn't you get or make the induction wands? Grant had more ways to apply induction heating to steel than a boy could need. Basically copper tubing hooked to the water and power and the business end might be a loop you pass over the work OR it could be two loops with a gap between them you can pass down the length of a bar, OR a flat spiral pad you can pass over the work and heat say the center of a car hood. There near the end he was making heat wands of the goofiest shapes he could come up with one of the coolest was a longish hairpin wand you could put inside a piece of pipe and heat it.

 

I'd LOVE to have an induction forge but I haven't had a paycheck job since the accident and can't afford one. <sigh>

 

Frosty The Lucky.

[iron quake]

Frosty,

I wish everyone who wanted one of these systems could have one, I really do their just that good. I’ve not made any really odd shaped coils. I have used the heater with other tooling to heat and roll up long lengths onto a removable mandrel like a coil spring. Most of the heating is done in rather short sections of about 6” or less. For making upsets, mortise, tenons and other short heats you just can’t beat it. Not only do you get the heat just where its needed but then being able handle the part without tongs is really nice. The process is so fast too its just crazy. 

 

I never got the chance to work with Grant as he passed away a couple days after my email to him about a system. He was a special fellow and I know many folks still miss him. I was able to work with Larry at Monster Metal, he was very helpful and I’m completely satisfied with my purchase. Given the direction propane prices are heading, he might see a lot more business coming his way.

[Devil-Forge]

We did a test between our burners DFPPROF and DFP

[ptree]

To test actual burner eficiency is a tall order. As Frosty notes a simple run it a couple of tanks and see how long they last is usuall sufficient for most.

That Said, having a long career in R & D and lots of flow testing experience I worked with several burner makers to do flow testing. What I did was to do simple air flow testing to see about improving the total flow thru existing designs.  When looking at most of the homebuilt designs made from plumbing fitting, the propane side is often condusive to a good flow, but the many threads shoulders etc are restrictive to the flow of air into the burner, causing less total flow. That then means restricting the flow of propane to get the flame you want. With care to good flow path design, the total flow through the burners can be improved by 10 to 40% depending on design. This does NOT refer to the combustion effiecency but rather to the simple mass flow through the device. NOW there is a link to effiecency when you turn up the fuel flow to overcome the restrictive air flow path. Not a direct linear link but indeed a link.

 

I currently use a Geshermier burner in a freon can forge. With ITC-100 I can easy weld high carbon steel. I run 3 RR spikes in the forge in production pulling one to forge and then rotating as each cools to keep the power hammer fed. I get about 9-10 hours from a grill bottle sized tank at full throttle.

 

A very good flow path, give a much better turn down ratio, IE the ratio from full throttle to minimum that with burn without stuttering or flame out. The really well optomized Geshermier burner in a heated forge will run from 15psi to no indicated pressure on an Admittley cheap and inaccurate gage. I preheat at 10 psi and run production at 10. I use that burner for its high effieciency and the ITC-100 makes a huge difference in the heat. I typically have little to no visible dragons breath. But I heat and beat at a rate the does not seem to produce badle scaled items.

 

In looking to have good fluid flow(air is a fluid) sudded changes in diameter cause turbulance. Turbulance causes flow restriction. Sudden increase in diameter is worse than sudden reduction in diameter. Sharp edges or shoulders also make for turbulance.A perfect flow path may not yeild enough turbulance for good mixing, but the turbulance that will always exist at the propane nozzle where the propane goes from high to low pressure seems to be enough.

 

Most big gas burner forges in industry operate totally differently than any small blacksmith burner I have seen. The industrial forges that I have worked with all used injection of the fuel into the eye of the high pressure blower and from the blower direct to the nozzles, not after the blower. this gives very nearly perfect mixing of the fuel and lets the forge piping be less of an issue. Imaging a forge with an interanl volume of a small car. Typicall 6 or 8 burners on two opposing walls. hard to balance but if the fuel is already fully mixed just pipe to the nozzle and have trim valves to set the flow(flame) at each nozzle. Think say 6 each 3/4" diameter nozzles with 20 PSI natural gas injected into the eye of a blower with a 4 foot diameter wheel case. Now imagine a $20,000 a month gas bill in 2005.

 

But at the end of the day, if the forge runs well, heats the items you need to heat, to the temp you need, then it comes down to Frosty's measure of fuel efficiency, how long does the fuel last.

[timgunn1962]

I am rather struggling to see what the test in the post #13 video is supposed to demonstrate, unless I am missing something important.

It looks to me as if both burners have chokes. The one on the left seems to have a plate choke which appears to be closed down quite considerably. The burner on the right shows a sliding-sleeve choke which appears to be fully open.

At the beginning of the test, the forge on the left seems to be running noticeably richer and cooler than the one on the right. The difference in dragons breath seems less marked later in the video, but the forge on the right looks significantly hotter immediately after the gas supply is turned off.

The test therefore seems to me to be comparing an appropriately-adjusted burner (on the right) with an inappropriately-adjusted one (on the left).

Obviously, the appropriate adjustment will vary according to what the user is trying to achieve.

Am I being unreasonably cynical about this?

 

 

 

[yahoo2]

Frosty, I think, noted that the performance of a fresh coat of ITC-100 is much better than an old coat.

 

I have seen it a couple of places, Ron Reil talks about it on his design page http://ronreil.abana.org/design2.shtml and puts it down to soot and fine scale dust sticking to the surface and absorbing radiation rather than reflecting it back into the forge.

[EricJergensen]

Yeah, if it doesn't look as white as it was originally in the visible range, it probably isn't as "white" in the IR range either...