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  1. #1
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    Building Pipe Burners

    Hi,
    I hope this is the proper place for this post? if not please feel free to move it.

    I need to build 2 pipe burners with about 36 inches of flame length.
    One burner needs to put out about 25,600 BTU and the other about 42,000 BTU

    I am building everything from scratch(burner,Venturis,etc...)except for the regulator. As cost is a limiting factor.
    I have been reading up as much as I can on the net on design and construction but still have a few questions I cant get answered.

    How do I go about designing these so that I end up with the BTU ratings I need?

    Also would a standard 11" WC regulator work or am I going to need a High Pressure(if so what PSI Rating?)regulator?

    I would also like to build this so as to use the least amount of propane as the burners will be running for a few hours at a time?

    And would it be best to drill the burner holes or cut slots for the burners?

    I'm sure more questions will pop up as I sit here and think more about this but I wont overload you all with more of Em'

    Here is a picture of what I am wanting to build


    Any help on this would be greatly Appreciated
    Thank You

  2. #2
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    Re: Building Pipe Burners

    -
    Last edited by steveinthewoods; 28-06-12 at 06:06 PM.

  3. #3
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    Re: Building Pipe Burners

    I had a bit of a play with a couple of pipe burners for work, several years ago now. They worked, but I didn't find them as easy to do as open-ended burners. Getting even flame distribution along the burner is just not a factor in open-ended burner design.

    My first attempt was with a slotted burner bar. When it didn't work, I went for drilled holes, which did. The slots in the first one were cut with an angle grinder, in the days before thin cutting discs. If you can afford to risk having to do it twice, thin disks might be worth a try. They'll certainly make the job easier; I was using stainless pipe and it wasn't fun drilling hundreds of 4mm holes.

    I used a commercial atmospheric gas injector (Venturi mixer), the details are downloadable from http://www.amalcarb.co.uk/downloads.aspx

    As you are making your own, it's worth getting hold of a copy of Mike Porter's book and having a good read of the stuff on Ron Reil's site.

    http://ronreil.abana.org/design1.shtml

    There's a useful BTU calculation spreadsheet on there that will let you calculate jet sizes and pressures for your desired output. If you have a lathe, drilled jets should be fine for the outputs you need. Otherwise, it's easiest to use MIG welder tips.

    Gas consumption is dependent on your heat output. 50,000 BTU/hr will use twice as much gas as 25,000 BTU/hr, and so on. Once your burner is set up, the gas flow and output can be varied over a fairly narrow range by adjusting the gas pressure. Flow varies with the square root of the pressure, so doubling the pressure will give 1.41 times the output. Conversely, halving the pressure will give 0.707 times the output. To get a 2:1 flow/output turndown, you'll need a 4:1 pressure turndown. I think you'd be doing well to get that.

    I also think you are better off using a low-pressure regulator if you can. One of the problems I had on the first one was getting an even burn; the flame was much bigger at the opposite end to the mixer. I don't know, but I suspect a smaller jet/higher gas speed would tend to make the problem worse.

    If at all possible though, I'd strongly advise that you find one that works well and copy it as closely as you can. You'll still need to understand what's going on, because you are unlikely to manage an exact copy, so will need to tune it, but it will greatly improve your chances.

    Regards

    Tim

  4. #4
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    Re: Building Pipe Burners

    Thanks for the replies.

    I'm going to buy the parts tomorrow and start experimenting.

    These burners will be used for a Hot Salts Bluing Setup
    The 25,600 BTU pipe burner will be used for heating plain water
    The 42,000 BTU pipe burner will be used to heat up the Hot Salts bath to around 292 degrees

    I will buy a standard 11" WC regulator like what is used for barbecues and see if that works. I cant seem to find any adjustable regulators locally and cant see paying the high shipping fees for one.

    Heres what I am thinking of doing/using for each one.

    On the burner that I need 25,600 BTU's on I will use 3/4 inch I.D pipe with one row of burner holes(I'm not sure what size to drill the burner holes or the spacing of them?) and use a small # 51 L.P orifice (i'll make my own orifice with a 51 drill bit).

    On the burner that I need 42,000 BTU's on I will use 1 inch I.D pipe with two rows of burner holes(I'm not sure what size to drill the burner holes or the spacing of them?) and use a small #51 L.P orifice (i'll make my own orifice with a 51 drill bit).

    On both the burners I will start the burner holes maybe 4 to 10 inches from the Venturis...I'm not sure what would be best or if this is even that critical? as both pipes will be about 48 inches long and I only need 36 inches of flame length.

    Since I cant get an adjustable regulator I will use a non adjustable 11" WC regulator (like used on barbecues) and maybe add my own petcock to adjust the gas flow on both burners? Or maybe forget this since it may not be necessary to help cut cost? then again it could be used to help regulate the temperature of the baths...?

    As for the Venturis/Mixer
    I was planning to use a belled pipe reducer drilled in the center for the Orifice/gas and then on either side of the gas input drill a large air intake hole then make a plate to go over them so I can adjust the air mixture.

    I'm hoping that the setup for each of these burners should get me close to the needed BTU/heat output and not waste to much gas since I will only be able to use the standard 5 gallon size (like used on Barbecues) tanks?


    What say you guys? Does this sound like a plan?

    I Appreciate the help and will look around and see if I can find the Book you mentioned

    Your help is most Appreciated
    Thank You
    Last edited by PredatorEdge; 07-09-10 at 08:23 AM. Reason: Added to

 

 

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