efficiency from a barrel evaporator

[82cabby]

Hi all-

I am wondering what I can do to improve the efficiency of my barrel evaprator. I averaged about 1.5 gallons of syrup per cord of wood last year and would like to see that improve! Here is a picture of the setup
, http://img.photobucket.com/albums/v282/dkutina/Maple%20Evaporator/P1030523.jpg

although there is now a pan about 28"x28" instead of the trays on top. The flue exits the top behind the pan and I have a blower on a speed control feeding the thing through the opening at the bottom seen here:

http://img.photobucket.com/albums/v282/dkutina/Maple%20Evaporator/P1030384.jpg

Filled with firebrick it looks like this:

http://img.photobucket.com/albums/v282/dkutina/Maple%20Evaporator/P1030513.jpg

Fire on the grate pictured. Air blows in from underneath. Pan is the same size as, and sits on top of the open top. It seems like I have to choose between a slow, gentle boil and filling the firebox every hour or ripping boil and fill it every 20 minutes (depending on blower speed). Either way, I'm going through a lot of wood per gallon of syrup.

Any help, ideas, suggestions, tips etc...will be appreciated!

Thanks!

[jmayerl]

Not sure how much space you have in the barrel but I would get the fire up close to the bottom of the pan. Also get some blanket insulation around the whole thing to keep the heat directed up at the pan.

[rookie]

my 1st year i had the whole barrell open to the smoke stack, then my 2nd year i made a small fir box in the front (about 18") then a verticle wall ramped up to my to my smoke stack, this made a huge diff. in my gph, not sure about wood consuption but I'm sure it was better than a a cord to 1.5 gallons. hope this helps

[82cabby]

blanket insulation? Like the pink stuff from home depot?

[CBOYER]

put your rig in a temporary shelter, at least protect the most windy side

[hkillam]

I've gotta believe that the very large mass of brick is absorbing a significant percent of the heat from the fire. But I also can't believe it would lower your gallons per cord THAT much.

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[82cabby]

I was led to belive that the firebrick was necessary. Not only to protect the barrel from over heating but to provide sort of a 'thermal mass' and keep everything hot. Does take it a while to get up to temperature though.

[jmayerl]

Ok, when I first responded the picture with the brick wasn't on there. I would take some of the brick out and use insulation blanket. You can get it at any refractor store or maple supply store. Its about $4 a sq ft and you would need about 8 I'm guessing. The bricks have 0 insulation value and are only used to protect insulation or arch board.

[jmayerl]

Also remember that having a flat pan, the best evaporation rate you will get is 1-1.5 gallons per hr per sq ft. Add that your outside I would cut that in half due to the wind and you can see it takes lots of wood to make syrup. Also if you run the pan as shallow as possible it will help alittle. We run about 3/4 of an inch deep.

[RileySugarbush]

Cut the top plate holes bigger and drop your pans down in. Then run them deep. You will almost double your rate and efficiency, but will get burnt rings like bathtub rings around the edges. Don't worry about the burning, the syrup will filter out fine, a little darker but delicious and you will be way ahead on time and wood. I boiled for years with four pans dropped all the way in.

[rookie]

blanket insulation? Like the pink stuff from home depot?
no its white, not sold at home depot, if you don't want to drive for some you can get it online from www.bascommaple.com put it under your brick , also i would stand the brick on its edge not on the flat like you have it. all this different advice probly has you kinda crazy huh?

[jfroe939]

I have a barrel arch. So I guess that counts for something. In addition to what others said... if you do keep the bricks in , at least stack them in on their side instead of stacking them flat. You're leaving even less room for wood. Because your fire box is so small, I would agree with other posts to replace your bricks with archboard or something like that. You're not going to ruin your little cooker overnight. The bricks main priority is to protect your evaporator and secondarily keep heat. The way you've got your bricks on the back end towards the stack... it looks like it's impeding air flow and that's a huge, huge deal with arches. I'd get rid of the back ones completely. Next, the rule of thumb for arches is to make your stack twice as high as your pan is long. For barrel arches make it 2.5X as long as your pan because these aren't ideal evaporators for getting a good draw going. And make sure not to close up your front door so tight that air can't get in and keep a good boil going. Now, as far a getting a good boil goes, hopefully you were using dry wood. Remember, too, that stainless is considered a highly insulating metal and that it doesn't conduct heat that well, so if your pans were thicker than what you'd use on the stove at home, that's not good. So how thick do you want? As thin as you can get would be my answer. I yes, definitely find a way to get that thing in some sort of shelter, even if it's just a tarp hung on some squared frame. Cutting the wind is a biggie and so is just the idea that you don't want cool, open air hitting your pan head-on. After all this, stand back and just sorta judge your setup overall while the fire's burning. If the inside of your firebox resembles a meat smoker more than a roaring flame thrower, it's either wet wood or something's happening that's keeping the smoke from getting sucked up your stack. If the flame inside is just a' roarin', then you know your heat-source isn't the problem so much and it's something else. Might even be that you don't have a damper on it and too much heat is going up the stack. I can't for the life of me imagine a scenario where you make all these changes and still only make 1.5 gallons of syrup on a cord of wood. That being said, barrel arches are a little trickier to keep a steady, constant flame going. Do understand though that you will most likely be adding more wood every 20-30 minutes at the least. If that's not the case and it takes longer for the wood you put in to get burnt up, that's a good indicator that you're not getting good draw up the stack and you'll want higher stack. I was really surprised when I wasn't getting a good flame on my barrel arch my first year. Couldn't figure it out why it wouldn't burn as well when I was using the same type of wood in my bigger arch and that was just crankin'. Then I added another 5-foot section of stack and that was all the difference. Nailed it. Hope I didn't sound condescending. I'm guessing these things will help (or your money back) ;)

[smokeyamber]

Ok, I have a barrel setup so I will mainly agree with most of what was said, take some bricks out, maybe use some blanket ( though I do not ). My setup has a cheapo fireplace grate ( tractor supply) and just half bricks to make the firebox, then I used perlite to make a ramp and laid brick on it. No blanket.

Biggest help on such a small rig from my experience was dry wood and adding a blower. Still it's small so don't expect fast boils... mine might have done 7gal per hour, but averages around 5. Small wood too, I loved using pallets when I had em, they really burn fast and hot for quick pickup if you happen to use not really dry wood. You mention feeding every 20-30min... try more like every 10 with small dry wood and you are talking a true evaporator .... my goal is to get stuff to melt ! The blower helps with that. One other thing I found that really did seem to help was to boil at NIGHT... the fire did not crank til after 9pm. Seriously, maybe it as the cold air making better draft or my boiling sodas, but from 10 to midnight I would crank... not sure if anyone else has seen this but I sure did.

A flat pan will give you nicer ( lighter syrup), but on something that size I don't think it will help with rates compared to the hotel pan setup, the pan setup just has more surface area even accounting for running deeper. My solution is to of course UPGRAAAADE and build something much bigger... everyone seems to do that, but enjoy your setup cause it is great cheap way to get the bug !!!

Overall your setup is really nice so have fun with it and start planning for your shack since having one is really nice when you do those 21hr boils ! :cool:

[treehugger]

Talking from experience, Until this year I used a flat pan with a barrel firebox. They are woodhogs, no question about it. What made a difference for me was better bricking (getting fire closer to the pan). I also made a cheap hood made from metal roofing. Blocking that wind helped a lot.

[82cabby]

Thanks everyone for the pointers! I will definately try a combination of all of them.
I do have a variable speed blower connected, so draw is not an issue.
As I said in the first post, I'm not using the cafeteria trays anymore. I am now using a homemade stainless pan that is about 28x28 inches. The thinkness of the pan may be a problem though. I don't remember the guage, but it is thick. I could make another thinner one if that proves to be the issue and finances allow.
I will add the blanket insulation between the brick and the wall of the barrel and try to rearrange the brick to get a bigger firebox.
Some sort of windbreak definately sounds like a good idea. I will come up with some sort of temporary shelter.

Treehugger- you mentioned a cheap hood made from metal roofing. How exactly did you set that up? I have toyed with the idea of some sort of lid that could keep the heat in, but let the steam out. But it always seems like I would get a lot of condensation back in the pan and defeat the whole purpose.

Thanks everyone for all the advice!

[Daren]

Loved reading the posts and all the ideas are perfect and you will get a much better boil with even just a few of them. I agree the most with the post about recessing the trays deeper in the arch. Bingo....kinda like wind block meets blast furnace. Forget about cleaning the pans all that much, but the place smells like cotton candy from about 20 yards and I had a boil rate average over a full season of 7 gph. each pan was 1 foot by 2 foot, two deep and one 4 incher.

[treehugger]

I made the hood with ridged metal roofing. I put the two big pieces over the the entire pan (in a triangle form) with the ridge running lengthwise to the pan. I held them together by drillin 3 small holes on each pices and with a few pices of twisted galvanized wire. On the "gable" side of the hood, I cut two smaller pieces, but keeping the eve open And again holding them together with wire. The important thing was to keep the bigger pieces over the side of the pan by at least 3" with the ridges facing out so the condensation runs on the outside of the pan. It was total redneck engineering, but it worked for my budget at that time.

[seclark]

when you say a cord of wood do you mean a full cord or face cord,also are you preheating the sap in any way or just adding cold sap to the boil.I have a barrel set up and did not use anywhere near that much wood and made 4 gallons+.I have a blower,hood and preheater and it's in a small shack.Make sure the wood is dry and wrist sized and as mentioned fire more often.Some one said there were to many bricks near the stack and I would agree,you may be chok:-|ing the draft to much.Also my bricks are on end not flat so there is more room for fuel.Good luck and hang in there it will improve.Believe me if I had found this site sooner I would have done things better from the start,great bunch of people here,always willing to help us back yarders out.

[82cabby]

I meant a face cord, sorry for not being more specific. I do preheat in a turkey fryer pot over another fire.
Do I need to be worried about draft since I am using a blower? I figured the bricks near the flue brought the flames and hot flue gasses nearer to the bottom of the pan.

[seclark]

you still need a good draft even with the blower.it looks like your stack is 6" but how high is it?my rig is 8" stack,I started with 6" but after the first year changed to 8" and it helped a lot.