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Thread: Rework AOF system on old King Evaporator

  1. #1
    Join Date
    Mar 2005
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    Albion PA
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    Default Rework AOF system on old King Evaporator

    Folks,
    This will be a thread to keep me motivated to get this project done before next season. Started out as just a need for new rail gaskets!

    Current set up with the AOF on the top rail:


    Current AOF is 2 inch sq tubing setting on the top rail. Several issues/ reason to change:
    1. Heat has warped the tubing out away from the original position. I had it fastened but the small screws were no match for the heat.
    2. being that close to the pan I had to modify it to add more air on the side opposite the draw off side.
    3. The top rail AOF expanded lengthwise about 1/2 inch when hot. Actually was cracking off the top edge of my front casting. (Not sure what I will do with that? May take the whole lip off?)

    So I am thinking of moving it down into the side of the arch where it has been noted most normal people put these systems! This will not be a kind and gentle repair/ rework. If you have a brand new shiny spotless evaporator and new arch you may want to look away!

    I have the steamaway and pans off and am noodling out the next moves. Basically cutting the old one into pieces, doing some fab work, taking out some fire bricks, installing the old reworked sections back in, re-bricking, and re-plumbing the air inlet system. I am going to keep the ability to throttle one side vs the other because I like more controls on things like this and maybe it will boil better with more air on one side vs the other?
    Will try to take a bunch of pictures and as usual write a lot.

    I am going to loose 2 inches of firebox depth. I have to move the rear drain exit location down 2 inches. Good news is that there is enough room for the 9 inch deep drop flues in the current arch. Just have to remove some sand.

    Here is a picture of my good friend Keith T firing the King arch. You can see the stainless sq tubing between the pan and the arch.


    I am also thinking of removing the parallel flow preheater from the inside of the steam away hood. I ran cold sap this year and really did not see and difference. It is hard to rinse the steamaway with all that extra hard ware in there too. That means I have to re-plumb the inlet for the sap too. As the steamaway will drop 2 inches and I will need two options for sap entering the float box on the steamaway.

    Comments are always welcome!

    Regards,
    Chris
    Last edited by Sugarmaker; 04-11-2019 at 09:22 AM.
    Casbohm Maple and Honey
    625 roadside taps + Neighbors bring some sap too!
    3x10 King, WRU, AOF and AUF
    12" SIRO Filter Press.
    2015 Ford F250 PSD sap hauler
    One Golden named Maggie, Norwegian Forest Cat named Lucy
    Too many Cub Cadets
    Ford Jubilee and several Allis WD's, and IH tractors
    1932 Ford AAB ton and a half, dump truck

    www.mapleandhoney.com

  2. #2
    Join Date
    Mar 2012
    Location
    Walpole, NH
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    Watching with lots of interest in how you do it. Thinking of modifying my old Algier arch for AOF. Already have AUF.
    Sugaring for 45+ years
    New Sugarhouse 14'x32'
    New to Me Algier 2'x8' wood fired evaporator
    2022 added a used RB25 RO Bucket
    250 mostly Sugar Maples, 15% Soft Maples. Currently,(110on 3/16" and 125 on Shurflo 4008 vacuum, 15 gravity), (16,000 before being disabled)
    1947 Farmall H and Wagon with gathering tank
    2012 Kubota with forks to move wood around

  3. #3
    Join Date
    May 2011
    Location
    River Falls, WI
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    Cool project Chris! I look forward to seeing your progress. I've dreamed about adding AOF, but I'm a long ways from taking the plunge. My rig is more than capable of meeting my needs now, and I only bricked it prior to the 2017 season, so I won't need to take anything apart for some time. Efficiency is always something to strive for, as is reduced emissions, so the thought is always in the back of my mind.

    Out of curiosity, with your current system, how much improvement over natural draft did you see?

    Ryan
    -Ryan


    Went off the deep end. Might be in over my head...

  4. #4
    Join Date
    Mar 2005
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    Ryan,
    Boy that is a good question about natural draft! I boiled with natural draft on a 30 inch x 10 foot Leader arch 20 years ago. (it was not mine) Had lots of time to do things as syrup boiled pretty much at a average pace.
    This arch of mine has had AUF since day one when I restored it. I added the AOF maybe 10 years ago.
    So AUF and AOF systems tend to be noisy! But they do work.
    When I build a fire and the draft door is open and AUF and AOF are not on yet I always think about just boiling without either and listening to the crackling fire and quiet. That lasts till I see the first bubbles in the syrup pan! Then I say, lets get rolling hit the switches and hear and feel the pans shudder and take off into a full rip/rolling boil across the front and rear pans!
    Without these you will get a lot of sparks out the chimney and a lot of black smoke., and a big fireball at the top of the stack. With AUF and AOF these are all greatly reduced and I believe you have a much more effecient burn of the wood. Yes you may burn more wood quicker but your also making more syrup quicker.
    Rule of thumb is 20 gallons of syrup per cord of wood. (now I do have a steamaway which helps) But I made 187.5 gallons of syrup an about 5 cord of wood this year which is closer to 40 gallons per cord. The AOF and AUF didnt hurt anything.

    My goal is always to inform and or mentor with these things on forums. But I am easily distracted and ramble a lot!
    Regards,
    Chris
    Casbohm Maple and Honey
    625 roadside taps + Neighbors bring some sap too!
    3x10 King, WRU, AOF and AUF
    12" SIRO Filter Press.
    2015 Ford F250 PSD sap hauler
    One Golden named Maggie, Norwegian Forest Cat named Lucy
    Too many Cub Cadets
    Ford Jubilee and several Allis WD's, and IH tractors
    1932 Ford AAB ton and a half, dump truck

    www.mapleandhoney.com

  5. #5
    Join Date
    May 2011
    Location
    River Falls, WI
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    I hope you don't think that I'm clogging up your thread here, but I enjoy the conversation. Great info, and thanks for sharing!

    I suppose it's different for everyone, but that kind of constant background does really bug me. My 4x14 makes enough noise just with natural draft! Thing sounds like a train if you're close to it. I suppose for me the low hanging fruit would be just AUF. Not a ton of tinkering and less noise than AOF.

    The sparks out of the stack are concerning to me though. We have a hollow basswood about 30' from the stack that has caught fire the last two years in a row. 35' in the air... I don't get too much black smoke, but I mostly burn softwood split pretty thin. It'd be nice with a blower to burn bigger chunks. rps20190411_105317.jpg

    Can't really see it in the picture, but it's ablaze.
    -Ryan


    Went off the deep end. Might be in over my head...

  6. #6
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    Albion PA
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    Ryan,
    If you see most of my posts I am pretty long winded. I can hunt and peck pretty good! I haven't started a new thread in a long time. Most of my work was a while ago this is just a upgrade I would like to do, and I will attempt to document most of it for the good of the folks that care to watch.
    If I were to put a number on it I would say the AOF is the thing that reduced the gasses and sparks the most and maybe by 90% That's just a guess. Straight AUF may actually add more sparks just due to the volume of air being added. I do understand the natural draft noise too! And they do get loud if your pouring the wood to them, which most of us old wood burners do!
    Regards,
    Chris
    Last edited by Sugarmaker; 12-22-2019 at 09:55 AM.
    Casbohm Maple and Honey
    625 roadside taps + Neighbors bring some sap too!
    3x10 King, WRU, AOF and AUF
    12" SIRO Filter Press.
    2015 Ford F250 PSD sap hauler
    One Golden named Maggie, Norwegian Forest Cat named Lucy
    Too many Cub Cadets
    Ford Jubilee and several Allis WD's, and IH tractors
    1932 Ford AAB ton and a half, dump truck

    www.mapleandhoney.com

  7. #7
    Join Date
    Jan 2006
    Location
    Oneida NY
    Posts
    11,547

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    Chris, read this before you make the change http://www.uvm.edu/~pmrc/Combustion.pdf
    I did it back several years ago. I used to get stack temps of 1400-1600 F and had a ball of fire out the stack as unburned hot gasses got to more oxygen. I also had sparks out the stack.
    Then I built a modified version of how the instructions say to do it. I can't say how much HP air mine because my blower is from 1904 and is belt driven by a 1 HP motor, but it works wonders. I used 2" square tubing, set 6" below the pans with nozzles pointed down at the prescribed angle of 10 degrees downward, spaced every 6" from one side of the fueling door, all of the way around the firebox to the other side of the fueling door. My HO blower is outside, under my head tank platform, it blows in thru a 4" PVC pipe with 3 long sweep elbows, then it splits into 3 pipes that are 3" diameter. One feeds a heavy galvanized pipe, 4", that runs in under the arch. It has 3 rows of holes, one top center and one on each side facing almost to the outer edge of the grates. The other 3X feeds a 2" square tube that drops down from the arch ramp at the back of the firebox. From there it feeds the 2" square tube. Each of the 3" pipes has a 3" brass ball valve to regulate the air flow. I'd need to recheck but I think the one feeding the AOF is open about 2/3 and the one feeding the AUF is open 25-30%. Each of the nozzles is 3/8" black iron pipe. I removed the firebrick to install the manifold, then ran a layer of full firebrick above the manifold and used plastic refractory to protect the manifold tubing and above the brick to the top rail. My ball valves were adjusted several time during the first season, until I decided where they are now is best, since then they have never been moved again. Those valves would not likely be 3" brass ball valves but I got them at $.10 a pound at scrap prices. The blower was $.02 a pound with the motor too. That motor just quit this season and I had to buy a new one. The old one had a patent date on it of 1895.
    Before I did this my boil rate was between 55-65 GPH, and I added wood every 7 minutes. Now I get a boil rate of 75-85 GPH and add slightly less wood each time and at 9 minute intervals. I can also add at 8 minute intervals and get 85-90 GPH but things move too fast for me that way, so unless I have experienced help in the sugarhouse I do the 9 minute fueling. My stack temps are now at 750-1100 F, I get no sparks nor ball of fire at the top of the stack because the gasses are burned while still under the pans where they do more work.
    As I say, mine is modified, the write up says a 3" pipe to carry the HP air to the nozzles, mine is 2" square and the blower is unknown. I could get it tested for pressure but it works so well I don't worry about it, besides I get syrup fast enough. My plaqns were to cut the nozzles back to even with the brick, but then I decided to leave the excess and just let it burn off, that didn't happen and the nozzles still look new, likely because cold air is keeping them cool. The nozzles stick out 1" to 2.5", but that has not proven to be a problem.
    I start my fire by laying the wood up alternating it for best air flow then I use a weed burner torch. As soon as it is going, I turn the blower on and it stays on even during fueling until the coals are burned up at shutdown, I don't even turn it off to fuel. Initially I did shut it off, but then my grandson forgot to shut it off one time and I noticed it made no difference, then it was no longer shut off to fuel.
    Dave Klish, I recently ordered a 2x6 wood fired evaporator from A&A Sheet Metal which I will be converting to oil fired
    Now have solar, 2x6 finish pan, 5 bank 7x7 filter press, large water jacketed bottler, and tankless water heater.
    Recently bought another Gingerich RO, this one was a 125, but a second membrane was added thus is a 250, like I had.
    After running a 2x3, a 2x6, 3x8 tapping from 79 taps up to 1320 all woodfired, now I'm going to a 2x6 oil fired and a 200-425 taps.

  8. #8
    Join Date
    Mar 2015
    Location
    Peoria, IL
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    634

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    One of the best things to combat noise of a pressure blower for AOF is put the blower in another room or outside. The additional 20' of pipe is worth the quiet it brings inside the kitchen. I was fortunate to have the opportunity to put my blower in the attic of our sugar kitchen and the only noise I hear is the roaring fire inside the arch.
    Camp Wokanda
    Peoria Park District

    2023 - 210 on 3/16 shurflo, sap storage shack w/ 1100 gallon tank - 123 gallons
    2022 - 210 on 3/16 shurflo, homemade vac filter & water jacket canner - 104 gallons
    2021 - 215 on 3/16 shurflo, added 2nd membrane to RO - 78 gallons
    2020 - 210 on 3/16 shurflo, upgraded hp pump on RO - 66 gallons
    2019 - 150 on 3/16 shurflo, Deer Run 125 dolly RO - 73 gallons
    2018 - 120 on 3/16 shurflo, 2x6 raised flue w/hood, homemade arch w/ AUF & AOF - 34.5 gallons

  9. #9
    Join Date
    Mar 2012
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    Walpole, NH
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    Quote Originally Posted by mol1jb View Post
    One of the best things to combat noise of a pressure blower for AOF is put the blower in another room or outside. The additional 20' of pipe is worth the quiet it brings inside the kitchen. I was fortunate to have the opportunity to put my blower in the attic of our sugar kitchen and the only noise I hear is the roaring fire inside the arch.
    Do you hear the air going through the pipe?
    Sugaring for 45+ years
    New Sugarhouse 14'x32'
    New to Me Algier 2'x8' wood fired evaporator
    2022 added a used RB25 RO Bucket
    250 mostly Sugar Maples, 15% Soft Maples. Currently,(110on 3/16" and 125 on Shurflo 4008 vacuum, 15 gravity), (16,000 before being disabled)
    1947 Farmall H and Wagon with gathering tank
    2012 Kubota with forks to move wood around

  10. #10
    Join Date
    Mar 2015
    Location
    Peoria, IL
    Posts
    634

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    Quote Originally Posted by BAP View Post
    Do you hear the air going through the pipe?
    Yes but its not an over whelming noise. The roar of the fire in the arch pretty much drowns it out.

    I should add that I piped my blower through pvc which is thick enough to keep the noise down.
    Last edited by mol1jb; 04-11-2019 at 05:58 PM.
    Camp Wokanda
    Peoria Park District

    2023 - 210 on 3/16 shurflo, sap storage shack w/ 1100 gallon tank - 123 gallons
    2022 - 210 on 3/16 shurflo, homemade vac filter & water jacket canner - 104 gallons
    2021 - 215 on 3/16 shurflo, added 2nd membrane to RO - 78 gallons
    2020 - 210 on 3/16 shurflo, upgraded hp pump on RO - 66 gallons
    2019 - 150 on 3/16 shurflo, Deer Run 125 dolly RO - 73 gallons
    2018 - 120 on 3/16 shurflo, 2x6 raised flue w/hood, homemade arch w/ AUF & AOF - 34.5 gallons

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