Greg B Smith

Glenn Herbert wrote:Welcome to Permies, Mark! For your restaurant-pan sized evaporator, your idea would probably work fine. You would really want to build an enclosure that the pan(s) could sit in with heat flow space underneath them, so you don't just have one super hot spot and ambient air around the edges. You might be able to get enough heat flow with a J-tube, but I think you would find that an L-tube works better and is easier to keep fed. Building an L-tube with an 8" wide x 9" high x 31" long firebox and a 27" or 31" total height riser (from the firebox floor) is very easy, requiring no firebrick cutting or real masonry skills, just large Lego stacking. See my photos above. The enclosure which you would need to build anyway to stabilize the core and pans can be just about anything, even stacked concrete blocks. You would need about 40 standard firebricks, and if you use blocks for the support structure, about 30 standard 8" concrete blocks. I like to use Durock or similar cement board for the firebox floor - it won't last forever but is cheap and easily replaceable. If you use firebrick for the floor, add another 16 or so to the brick total. You would want to fill the space between enclosure and firebrick core with perlite, best if mixed with a small amount of miscellaneous powdered clay and moistened before filling. This will support the firebricks securely.

All this material will cost hundreds of dollars less than a Dragon Heater core alone.

If I’m following correctly, the box can be made of cinder block with clay/perlite mixture to stabilize and insulate the fire brick core. The flame would be exposed to the pan bottom. The open flame would also be in contact with the top row of cinder block the containment wall is built from? Or is perlite/clay extending up the top row of cinder blocks also?

This is the pic of the syrup coming up.

This is a friends setup.

The furnace is built entirely out of fire bricks with a 16” drill case for stove pipe. There is a dirt berm inside the brick that funnels the flames to within 3” of the pan all the way to the chimney. Flames were going all the way past this 8’ long pan. The stack was producing NO smoke at all. Completely clean burn. They use split pine for the wood as it burns fast, hot, and nearly ash-less. They added about 10-12 sticks every 10 minutes. This is a 200 gallon pan that produces around 30 gallons of syrup every batch. Yeah, brix  on sugarcane juice is a little higher than maple sap. LOL. He also has a 12’ “worm” pan that is continuous flow but he said it would work you to death. LOL. If it was any worse than keeping up with the 200 gallon pan then I don’t want any part of it.

I have another friend that cooks in a 30 gallon sugar kettle with propane. The funny thing is, other than the time it takes to grind extra juice and bottle the extra syrup, the labor it takes is the same on the actual cooking. 200 gallons wood fired verses 30 gallons propane. Kinda crazy to me.  

Glenn Herbert wrote:That first one was a bit undersized for the 8 sf pan. I added a couple of bricks to the L-tube length and it seemed to work better, but I never got the chance to really test it. It would work great for a 4 sf pan like the OP's, and could be built entirely in/on a base of a dead kitchen stove.

So I need a metal box with a shallow channel that can funnel exhaust across the pan bottom and out the other end to the vent. I’ll be on the lookout. That’s much easier than the  55 gallon drum I had planned.

Looks like you used just plain galvanized vent pipe and accessories for your stove pipe. Is that correct?

I have a small JD tractor with front end loader and forks. I would like to build my rocket fired syrup evaporator on a pallet so it can be moved out of the way when not in use. I’m thinking lay a sheet of hardie on the pallet and then cover with half cinder blocks laid down flat for the base. Split fire brick would be the bottom of the fire box.

So from the ground up as follows: pallet, 1/2” hardiebacker, 1/2 cinder blocks with no space between themselves to form a solid floor, one layer of fire brick splits for fire chamber floor.

Would this work or do I need to find a different approach for being able to move the evaporator?

thomas rubino wrote:Ok;
You have a much smaller pan than I have seen in northern sugar shacks.

If it will fit over a barrel then that will work.

You may need to play with the diverter gap, it can't be too close.

For your "Work" force a 4x8 sheet of rigid insulation would work.

Be sure to use a good size exhaust stack.

This pan will be a stainless square pan 24”x24” on bottom with sloped sides. The top of the pan is 30”x30”. Just shy of 12” tall for a total of 30 plus gallons. It’s a batch pan.

This one will be used for small batches of syrup when testing new varieties of cane and or sorghum. I currently have 10 varieties of cane planted. In the future it will be used as a bottling vessel for a 200 gallon pan which will be 3’x8’ on the bottom and a much larger furnace to fire it.

This is a pan I am modeling mine after.

thomas rubino wrote:Hey Greg;
Well, you are boiling sap so it's going to be hot.
If I'm understanding correctly, the barrel is open top and there to help shield the heat.
I would consider using an insulated riser, it would concentrate the heat inside the riser giving the most out of the top under your pans.
Yes, I think a diverter to spread the high heat across all your pans is a good idea.
Consider, using a steel box as a stratification chamber that collects the heat, and then have your vent pipe leave from the lower part of the box.

For the workers, you could use 4x8 sheets of the rigid foil face insulation board standing on the edge to block quite a bit of the radiant heat.
Lots of fresh cold water, maybe misting fans, start before dawn and quit after lunch?

I’m not following on the stratification box.

What I was thinking was an air tight system with the exception of the firebox intake and exhaust. Heat would go through the riser to the pan bottom which would be gravity sealed to the top of the drum with firebox rope. Hot air would flow between the diverter and the pan bottom out to the barrels edge. The air would then flow around the edge of the diverter and down into the void/chamber underneath the diverter. From there it would exhaust out the stack.

The diverter would be attached to the top of the riser and extend to the edge of the barrel but not connected to the barrel. Air could pass between the side of the barrel and the edge of the diverter. Think of the diverter as paper plate with a hole in the center to slip over the riser. Air would be forced between it and the pan and over the edges of it. Hope that makes sense. If I have to draw it we are screwed. My art skills suck!

And when I say workers I really mean me! lol

Because sugarcane syrup needs to be skimmed for long periods of time, standing close to the stove will be hot work unless it’s cold outside. Here in the south that doesn’t happen often.

To concentrate the heat on the pan and shield the workers from heat, here is what I’m thinking:
L in a barrel extending to a couple of inches (actual height to be determined) from the top to concentrate the heat on the pan bottom. Diverting plate to spread heat across the bottom of the pan (this is hard to explain but would not affect the direct flow from the riser). Vent stack inserted below pan and heat diffuser to exhaust and possibly shielded to insulate radiant heat from workers. Vent stack can be as long as needed for better draw.

The questions I need to figure out is how much insulation for shielding workers can I add before the internal heat equalizes and draft and draw of air decreases or worst case stops.

Im thinking layers of mineral wool against the barrel and/or possible partially filling the barrel with perlite. Whatever to minimize the radiated heat.

thomas rubino wrote:Ha Ha, Well Greg you are talking to northern boys.
We know all about maple sap... and in my case virtually nothing about sugar cane.
Glenn is by far the more knowledgeable about this subject,  Montana has no natural Maple trees or any sugar cane at all.

As far as consulting goes you could continue to ask and receive answers right here at Permies.
I am always open to a scheduled phone call but my evaporator knowledge is limited. (No charge) you can contact me at dragontech@blackfoot.net

Thank you. That is very kind and I may take you up on the offer.