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Heating and cooling: gasifying boiler primary air control

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  1.  
    • CommentAuthorjohnnyh
    • CommentTimeJan 30th 2016
     
    Hi to all,

    wondering whether anyone can tell me which parameter is best to control primary air on a gasifying boiler? Would it be better to use oxygen levels in flue gas or flue temperature or something else entirely?

    Any info would be much appreciated,

    regards,

    john.
  2.  
    Hmmmm - can't measure either of your choices at present (flue probe melted after flue fire) but pretty sure flue temp would be v difficult due to the stages in the life of a burn and how to relate the right amount of air to a particular temp. Now, I use colour and size - I look for a big blue flame just bouncing off the bottom. And have seen a ref to the same before from another manufacturer. My installer used the noise the thing makes (and years of experience obviously!). Goof luck.
    • CommentAuthorowlman
    • CommentTimeJan 31st 2016
     
    My boiler uses both; a Lambda sensor in the side of the flue exit and a temp sensor in the chamber just before the inline flue fan. Together, these sensors adjust motorised dampers on the front of the boiler and hence regulate primary air.
  4.  
    Ahhhhhhh, so much more to go wrong, says he jealously :wink:
    • CommentAuthorowlman
    • CommentTimeJan 31st 2016
     
    Initially that's what I thought before I bought it. I did cast an eye over the ease of servicing, and it all seems very simply put together with easily accessible robust components, I've been pleased so far.
    • CommentAuthorjohnnyh
    • CommentTimeJan 31st 2016
     
    That's the set-up i'm going for, motorised air inlets controlled electronically. Will be a bit more fragile than a fixed air system but hopefully more efficient and will adapt to changing fuel supply.

    i have found out that the level of secondary air is easy enough to get right simply by trying to keep flue gas oxygen at a steady level but primary air is more about keeping the gas production high but constant and that seems much more complicated. It's probably not practical to measure anything in the fire bed as sensors won't last or stay clean but that is possibly what industrial gasifiers do. I have read a lot over the last week about comparing co/co2 ratios, firebox pressure etc. etc. but that is probably outside the realms of practicality for me as well.
    Then again the domestic boilers that have automatic air control seem to do so with only a flue temp. sensor and an oxygen sensor so i am trying to find out what they do to determine the primary air setting.
  7.  
    Posted By: johnnyh... i have found out that the level of secondary air is easy enough to get right ...
    ... so i am trying to find out what they do to determine the primary air setting.


    I'm curious to know more about this secondary air inlet that you have on your Orligno. On my Orligno I only have a single adjustable air inlet; round one on the main combustion fan sitting just above the lower combustion door. I can't see anyother seconary air inlet. Any chance of a picture as I'm starting to think your Orligno is different in some way to my Orligno 200 40KW.
  8.  
    If you're interested in flame colour to adjust air inlet settings here's an interesting thread ...

    http://www.hearth.com/talk/threads/blue-gasification-flame-fact-or-fiction.80266/

    What I find is the colour of the flame is consistently yellow\orange despite wood or air inlet setting. I'm gradually increasing the primary (and only) air inlet until I see a reduction in crap building up inside the loading door. I suppose the state of any ash in the lower chamber can give a clue as well.
    • CommentAuthorjohnnyh
    • CommentTimeFeb 3rd 2016
     
    My orligno has a fan with a rotary type adjustment, then below the fan are two screws which adjust the secondary air that exits inside the refractary concrete nozzle. Behind the fan mounting plate there are two sliders that are secured with nuts and these are the primary air inlets.

    just tried taking a photo but it's too dark out there in the man cave.
  10.  
    Posted By: MonsterMonsterIf you're interested in flame colour to adjust air inlet settings here's an interesting thread ...
    Yes, I am. Thanks
  11.  
    Posted By: MonsterMonsterIf you're interested in flame colour to adjust air inlet settings here's an interesting thread ...

    http://www.hearth.com/talk/threads/blue-gasification-flame-fact-or-fiction.80266/

    What I find is the colour of the flame is consistently yellow\orange despite wood or air inlet setting. I'm gradually increasing the primary (and only) air inlet until I see a reduction in crap building up inside the loading door. I suppose the state of any ash in the lower chamber can give a clue as well.


    I checked my flame in a bit more depth and directly in the nozzle it is light blue turning to a light pink to peach to soft orange extending into the concrete funnel. Adjusting the circular primary air intake only made the flame bigger or smaller but very little difference in colour. I'm currently burning naturally seasoned mixed hardwood, mostly ash, at between 20 to 24% mc. I think the type and quality of fuel will have more an effect on flame colour.

    Apparently a blue flame is the ideal.
    • CommentAuthorjohnnyh
    • CommentTimeFeb 7th 2016
     
    I have to open the lower door to see the flame. Closing it again seems to change the flame after i've adjusted the air to suit.

    I need a viewing window type thing. Anyone got one on theirs?

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