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"BLUE" Gasification flame, Fact or fiction?

Post in 'The Boiler Room - Wood Boilers and Furnaces' started by Armaton, Jan 8, 2012.

  1. Armaton

    Armaton Member

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    Since I am in the market for a 6-10,000 dollar boiler, (plus install), figured I'd get some input. I got on youtube and viewed many vendor and individual videos on 9 different advertised boilers, as well as a video on a homemade gasification barrel stove, and the only video (IMO) that had a "TRULY" blue flame was the barrell! All the boilers gasified, and one even had a slight blue tinge, but none seemed to have that nice blue flame, except the barrell! Why is that? Figure if anyone could coax that pretty blue flamefrom a boiler, it would be the vendors. I bring it up not to irritate, but to get information. The boiler that I am almost certain to buy also was lacking in the blue flame category! Comments?

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  2. eriesigtau

    eriesigtau Member

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    My econoburn usually has a blue flame once it gets up to temp but does have some orange and white as well. The blue seems to be more in the middle kinda like a propane torch.
  3. afblue

    afblue Feeling the Heat

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    I will have to say a "blue flame" is not what defines the efficiency. Its not going to look like a blue natural gas flame. My Paxo 25, its blue/purple when it first starts gassing, and its smokey, I call it a "wet flame". as things roll on its a bright orange/yellow and putting out some serious heat, the last 1/3 of the burn, its practically white with a tinge of blue on the edges and almost feels like you need torching glasses to look at it , and the fire block is glowing orange where the flame hits it. My infrared temp gun will give me random readings in the 16-1800deg range when I try to point it at something in the lower chamber, and when I point it at the glowing brick it gives me an error. So not knowing exactly how hot it is, its friggin hot!!!! so "blue" doesnt indicate clean burn.
  4. My biomass consistently has a blue flame or blue tinged flame. But it is very hard to take a good picture of the flame -- always comes out more orange than blue. Haven't tried a video.
  5. stee6043

    stee6043 Minister of Fire

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    Fact. But keep in mind that keeping that blue flame blue when you vary wood type, moisture content, weather, etc. is a whole different story than getting it once for a photo op.
  6. hobbyheater

    hobbyheater Minister of Fire

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    The modern gasifiers burn clean. Look at the advertised flue gas temperatures. The ones with the lower flue temperatures are able to retain more of that heat.

    You have a real adventure ahead of you in selecting a boiler. There are lot of good ones out there. There was only one in the market for me to choose from.

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  7. woodsmaster

    woodsmaster Minister of Fire

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    Fact. I often get some blue flame when things are very hot. usually second half of burn. here's a video
    of mine spiting out some blue.
    http://youtu.be/5Hq1WvFHTE4
  8. Duetech

    Duetech Minister of Fire

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    As sstee6043 stated there are variances in conditons and fuel types and one generic setting will not garner the same exact results for each fuel setting. Some of the more sophisticated boilers have controllers that will vary settings to gain the best output. Wood properties change also while burning and as the fire progresses fewer volatiles will be present and more true gasses like carbon monoxide and hydrogen will be burning. Once my EKO40 was up to temp it was generaly adjusted so a predominantly blue flame could be seen for most of the burn however as fuel quantity diminishes the color changes again.
  9. ozzie88

    ozzie88 Member

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    I found out that burning different types of wood give you different colors. They all will burn good, hot, clean,etc. in a good boiler but when I burn Birch I get a really good blue frame,so burning say ash,maple, burns mostly hot white & orange but all burn HOT!

    Hope that hepls, try birch,should get blue flame.
  10. deerefanatic

    deerefanatic Minister of Fire

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    Mines mostly white/orange.... Tough to tell though when the entire bottom chamber is glowing orange!!!
  11. ISeeDeadBTUs

    ISeeDeadBTUs Guest

    Fact.

    But as others have said, the color of the flame is useful for photo ops... and that's about it. If I have to be away for a long day - like today -and I over-fill the GW with amix of Maple/Oak, I will get a ridiculously large coal bed at the end of the burn. Heaping that bed up over the air inlets will make blue flames that you'd die to see. But since there is nearly no smoke at that point, I doubt there is much secondary burn. A roaring fire will heat the H2O faster than the dancing blue flames.

    Don't keep us in suspense... what unit are you gonna' buy??
  12. Armaton

    Armaton Member

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    I really like the Varms, either the Vedolux 30 or 37 will do for me since I intend to have 1000 gallons of storage. Not that I "Dislike" any of the others. I feel the Lamda control units are nice, but for my application, not worth the cost, (since I'm certain to be voluntarily playin with the thing for the next 5 years anyway). The Vedo's have a smaller footprint, easy cleaning, and lighting, and I like the fact that even though I have a bigger chimney right now, when it burns out, as it surely will, I could go to a less expensive 6 inch if I so choose. I have just been waiting for Clarkbug and Floydian to get theirs online and get some experience with them. It's too late in this burning season for me to realistically put one in, so gonna closely monitor their threads just to make sure, before I pull the trigger.


    Armaton
  13. woodsmaster

    woodsmaster Minister of Fire

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    Might be able to get it cheaper in the off season to.
  14. EffectaBoilerUser (USA)

    EffectaBoilerUser (USA) Member

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    I've noticed that with my effecta lambda boiler the flame is blue/purple for several inches when it leaves the ceramic and stainless steel burner tube.

    However, when I take photos of this flame it automatically turns to an orange flame (I'm not a photography wizard but there must be a reason for this).

    I've done a lot of investigation into boilers and have determined that the most important measurables are:

    1.) Temperature in the secondary chamber.

    2.) Temperature of the flue-gas as it leaves the chamber.


    To be accurate (and be able to accurately compare between different brands of boilers), both of these temperatures need to be checked with internal temperature probes.

    I have attached a graph of these two temperatures during a typical burn in my effecta lambda boiler. The effecta lambda boiler has an internal temperature probe located in front of the fan where the exhaust exits the boiler and goes out the chimney. This temperature is displayed on the control panel. My effecta lambda boiler (via. the control panel) keeps track of the "total run time" of the boiler and also the "total run time between cleanings" on the boiler. What I have discovered after 1,700 hours of operation with my effecta lambda boiler is that at 200-250 hours (approx. 1-1.5 months of operation) the smoke temperature begins to rise approx. 30-50 C due to the coating of ash on the heat exchanger tubes. Once I run my cleaning brush through each heat exchanger tube a few times the smoke temperature drops back to where it normally runs (approx 170-180C).

    Lastly, I would highly recommend that you talk (at length) to several owners/users of the boiler you plan to purchase so that you can get good first hand ,experienced feedback. If possible, I would visit locations of actual boiler customers to see the boilers in operation first hand.

    Thanks,

    Brian
  15. EffectaBoilerUser (USA)

    EffectaBoilerUser (USA) Member

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    Sorry about that.

    I have atatched my burn data graph for my effecta lambda 35 boiler to this post.

    Hope this helps!

    Brian

    Attached Files:

  16. hobbyheater

    hobbyheater Minister of Fire

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    Dr Hill's Jetstream design still shows a very efficient operation. Pictured is the flue gas temperatures before and after the draft inducer port.

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  17. pwschiller

    pwschiller Member

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    Low flue gas temps may be due to efficient operation through nearly complete heat transfer, but they can also be due to excessive air being introduced. If the temp in the secondary chamber is averaging 1800 F and the average flue gas temp is 350 F, that seems to indicate a fairly efficient boiler. It's not clear to me how your photo is confirming efficient operation of your Jetstream.
  18. hobbyheater

    hobbyheater Minister of Fire

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    Western Hemlock, I believe, gives off 6900 BTUs per lb of wood. 145 lbs of wood consistently puts over 800,000 BTUs into heat storage. Storage is 1000 gallons.
    On an average, I go between 40- 64 hours between firings. Heat rise in the storage is small in the first 1 1/2 hours of operation but once the large refractory component heats up so does the transfer to storage. The longer the burn, the greater the efficiency. Heat is still transfered to storage for up to 4 hours after the fire is out.
  19. maple1

    maple1 Minister of Fire

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    I'm in that boat too - move over. Beer?

    I can't get enough info on the Varms - continuously watching this place for more real world feedback. My eyes are firmly on the 40 though - the fact that it operates on natural draft with no blower required (if your chimney is high enough, that is) seems to me to be a hugely understated advantage. Add in what looks like real easy cleaning and very efficient design, and they've got all my attention. I hope to have my own Varm install thread on the go this time next year.
  20. thecontrolguy

    thecontrolguy Member

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    I would have to agree with this as well. Really, the only way to truly assess your air ratios is to use a Lambda sensor on the outlet flue. This will clearly indicate that you do not have too much excess air. As the fuel burns, and you are at about 4 - 5 % oxygen on the sensor, then you can assume you are getting some pretty good efficiencies. Any less than this and you might get into trouble with CO production. Not only is CO toxic, as everyone knows, it is also a good fuel in the right conditions. Read that 'EXPLOSIVE'.

    You could try borrowing a Lambda sensor and see what your 'typical' is. Or, try a one-wire Bosch type, for automobile use, and home-brew an electronic meter / power supply unit to be able to test the burner at any time. This is the direction I am heading. Anyone know of a cheaper O2 meter for stack testing?
  21. heaterman

    heaterman Minister of Fire

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    In a nutshell

    Blue = burning pure vapor like natural, propane or wood gas

    Yellow/White = a liquid based fuel such as fuel oil or some type of gas with high moisture content or some solid matter mixed with it.

    I have seen the same gasifier produce blue as well as yellow/white with different loads of wood. I have also many times observed both colors in the large secondary chamber of a Garn where the flame is bright yellow at the front and turns blue toward the back.
    Personally, I feel that a wood gasifier is running a tad weak in the O2 department if the flame is blue. It may be that it is most efficient when exhibiting a flame of that color but I would like to see a bit more margin for error on boilers with manual air adjustments.
  22. CTYank

    CTYank Minister of Fire

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    It's been well known for a long time that yellow flames in a wood-burner indicates presence of free carbon in the gases. Some of you are just reading too much into this flame color thing. If you have some net excess air and temps > 1000 F where the secondary air and the volatiles meet, you can have complete combustion, regardless the color scheme.

    Often, when I toss in a few splits of black locust, I'll see a rippling wall of yellow flames about the pieces for a minute or two, then it's basic blue. Meaning: it lights and burns.
  23. woodsmaster

    woodsmaster Minister of Fire

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    The way I see it is that if you don't have smoke coming out the chimney it's burning fine.
  24. hobbyheater

    hobbyheater Minister of Fire

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  25. boilermanjr

    boilermanjr Member

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    Flame color varies with the stage of combustion and the eye of the particular human or camera making the recording. In the boilers we sell, often times the bluest flames come during the poorest combustion with wet wood. Most of the boilers discussed in these threads have E.U. data if not U.S. data. Ask for that information from your prospect suppliers. Don't get hung up on flame color.

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