Maple Syrup

SMD

New Member
Dec 12, 2017
18
Batesville, IN
Hi All,

Enjoying my E250 to heat my house and barn with a hydronic system. Liking it. But.......

What if I used the E250's ability to product steam so that I could boil maple sap into maple syrup during maple season? The E250 is rated to 15 PSI of steam.

Close hydronic system in Late Feb. Place steam controls on the boiler. Run the steam through a pipe into my syrup area, run flexible copper tubing through a wide pan with sap in it. Steam at 15 PSI runs through the pipes (that's 245 F). Sap boils and you get maple syrup. A lot of it, because the monster will put out close to 180K btu of steam.

What are your opinions? Would 15 PSI be enough to boil sap efficiently?

Thanks,

Andrew
 

peakbagger

Minister of Fire
Jul 11, 2008
4,610
Northern NH
I will let you run the numbers. It takes about 1000 Btu/lb of water to convert water to steam. There are about 8 lbs of water per gallon. So your wood boiler at full burn is good for 180 gallons of sap per hour or 3 GPM. One trick to improve the efficiency of the process by capturing the hot water vapor coming off the sap to preheat the incoming sap. I think commercial evaporators use three stages of heat recovery.

Of course with the right technology and enough money you can install a multiple effect evaporator used in the sugar and a lot of other industries to evaporate water. The problem is that in order for maple syrup to taste like maple syrup the sugar is actually caramelized in the processing and that is what give its flavor. The current technology of reverse osmosis filters is used to drive out a lot of the water from the sap and then they switch over to the pan type evaporators with couple of economizers for the final processing to get the flavor.

Some "entrepreneurs" (AKA crooks) over the years figured out that they can buy beet sugar and mix iit in with the raw sap and come up with a product that tastes like pure maple syrup. I believe that there is now a test for this adulteration and if someone is caught the fines are high.

There is huge maple syrup processing facility run by a hedge fund in Island Pond VT and I would not be surprised if they haven't researched multiple effect falling film evaporators. https://en.wikipedia.org/wiki/Multiple-effect_evaporator. We had two line ups of these evaporators for black liquor in Berlin NH and they were 5 stories high. They took weak black liquid (a byproduct of the pulping process) at around 1% concentration and got it up to 70% concentration which we then burned in a chemical recovery boiler to supply steam for our process. The black liquor came from hardwood trees with a lot of maple in the mix and had a distinct maple odor. A byproduct of certain hardwood pulp mills used to be vanillin which is sold as artificial vanilla extract.
 

SMD

New Member
Dec 12, 2017
18
Batesville, IN
Thanks, all for your input. I especially like the offer to give feedback on the syrup.....

Like the ideas on efficient sap boiling.... was thinking starting this next season just boiling, then moving to RO or other efficiencies if I ever get more serious about things. boiling 3 gallons of sap per minute would be pretty impressive.

I spoke with Woodgun, it turns out my boiler is designed to heat water, it doesn't have enough space above the firebox to make steam.

Not being one who gives up easily..... what if I replaces much of my boiler water with propylene glycol, then ran the wood gun at 300F? Assuming I could get 10 gpm of flow, and my sap is boiling at 220, that would yield a temp difference of 80F. That comes out to about 280K btu per hour, which is well over what the woodgun can put out.

Will this work?

Andrew
 

SMD

New Member
Dec 12, 2017
18
Batesville, IN
Maple1, I have a place to set up a liquid heat transfer pan right now, ready to go, with water and electric already in place. For a wood fired arch I'd have to build a new shed. It makes a lot of sense for me to look into this.

Also, high pressure steam is out of reach for most syrup makers- the boilers and pans are just too expensive. This technology would allow all syrup makers to use liquid heat transfer for their pans cheaply. At 300F, it's probably hot enough to impart a really nice flavor to the syrup, with no risk of burning. This technology could potentially help the small farmer make high quality syrup cheaply and easily.

Andrew

Forget all about this kind of stuff.

Just get or make a purpose built stove/evaporator.
 

E Yoder

Feeling the Heat
Jan 27, 2017
294
Floyd, VA
I'd love to see pictures. From my experience with OWB R&D, about 10% of my ideas survive, but a few good ones come through. It's a lot of fun and hard on the wallet. :)
 
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mike van

Feeling the Heat
Apr 24, 2013
359
Kent Ct
I will let you run the numbers. It takes about 1000 Btu/lb of water to convert water to steam. There are about 8 lbs of water per gallon. So your wood boiler at full burn is good for 180 gallons of sap per hour or 3 GPM. One trick to improve the efficiency of the process by capturing the hot water vapor coming off the sap to preheat the incoming sap. I think commercial evaporators use three stages of heat recovery.
Are you sure of the 180 gal/hr? Maybe in the cooling tower of some nuke plant? After 20+ years on my old Leader, I bought a new one Feb 1, 2 x 61/2, not huge but for 150 taps its just fine. It'll do 25 gal per hour with good dry wood. 180 sounds really out there
 

maple1

Minister of Fire
Sep 15, 2011
9,879
Nova Scotia
Yes, something is off kilter in those numbers.

We have a 5'x16' with a 10' piggyback pan on top. Feeding a 2'x8' oil fired that finishes. That setup usually runs on a sap feed of 4-5 gpm. Could do more if you really push it, but no need with the RO ahead of it.

I think the thing that is getting missed here is the fact you need to evaporate 39 gallons out steam of 40 gallons of sap to be left with 1 gallon of syrup. Which as already mentioned takes big BTUs.
 

SMD

New Member
Dec 12, 2017
18
Batesville, IN
Hi maple1. Yup, there is a problem there. It takes 1000 BTU per pound to convert hot water into steam. That's 8000 btu per gallon, not 1000.

My e250 could boil about 30 gallons per hour.

Physics has a way of sobering you up pretty rapidly.

Your rig sounds really nice! How many trees do you tap?

I'm still working on the hydronic evaporator. Looks like propylene glycol won't work. Moving in the direction of a food grade oil based fluid. Food grade and would be obvious if there was a leak.
 

maple1

Minister of Fire
Sep 15, 2011
9,879
Nova Scotia
Around 35,000.

I'm not sure where the disconnect is in the numbers but I would bet there is no way you can do that with your Econoburn. I think a big part of it is heat exchanging. Evaporators have the sap and the (very hot) fire separated only by a thin layer of stainless sheet metal, basically. Plus it is being constantly fed cold sap.