Mike Schmatz

Here is a pic of it running with the shroud around the pan. Thought I already had it on here.
Just water though, still no sap!

I agree especially at the very bottom where the grate drops into the bottom tube. The longest I have run it is about 2 hours and the ash wouldn't fill a serving spoon. During the season it will run about 12 hours in a day next to my conventional arch so that will be a test. It will also get fed a wider variety of fuel so some may produce higher ash amounts. The nice thing about the ash is that you can scoop it right out of the bottom while it is running if I need to. It just drops through the grate into the bottom tube.
I have some heavier stainless to make a new grate, I was thinking of 1/4" to 1/2" slats instead of holes but we will see.

10 day forecast still has no tapping weather in it.

Good morning,

The tubing came from a steel supply outlet. It was a scrap from a much larger piece and it is 1/4" thick. I thought that should last a while.

For a grate I just use a 1/16" thick piece of steel with 1/2" holes drilled in it the full area of the 6" X 6" tubing.

The notches on each side of the top of the tube were to hold the pan 2" above the riser giving room for gases to escape in all 4 directions.

The perlite keeps the cabinet from getting warm at all. The only area subject to heat is the very top where the riser outlet enters the shroud around the pan.

Since it is still too cold for sap here in NY it has not had a long term test only short burns for experimenting. I am ready for some warmth though. The tank is ready the tubing is ready I am ready but Mother Nature has her own ideas.

Thanks for looking
Mike

I will post updates once it is producing and let everyone know how it worked.

Just a couple when it is running

The surface area is the determining factor for evaporation. You can expect 1 gallon of evaporation per hour with one square foot of surface area. A pan with flues in it will double that evaporation rate. I am using a flat pan. I also run a 10 sq foot pan on a more traditional arch.

I think I can add some more pictures with this post of the prototypes.

I would also like to use the flow from the flue to warm my butt down the road.

Using two plates that cover the inputs I can control the fire pretty well or even shut the stove right down by starving it.

Your idea of perhaps 4 rockets in a row may be in the future. Spreading the flow of heat exiting the riser will also be something to work on from the prototype when 2015 syrup season is over.

Thought about it last year but didn't put much time or effort into it. In theory it should consume much less wood due to the efficient operation of the rocket type stove.

First rocket stove attempt was just some 3" galvanized pipe. It worked and I learned a few things about the principals.









My second attempt was a typical j type rocket used in a mass heater but it would only boil a small pot with the exhaust. I made that out of some fire brick and an old flu liner from a chimney. Not well insulated. The higher temps are in the combustion area and I think this would work if you sunk a pan into the bottom of the j shape of the rocket stove but you would need to fit the pan into that area very precisely to keep the air flow without introducing any leaks.












My third attempt I used some 6" square tube made of 1/4" steel. I used a v shape to move the fuel and therefor the flames closer to the pan. Once I welded it up I fired it and it would boil a pot with a gallon of water but still not what I needed to utilize my 2 sq foot pan that my in laws made me for the top of my small wood stove.





4th attempt I changed the air intake to make this thing really rocket. Once I added the extra air intake it would boil a larger pot with two gallons of water no problem.

Once I did that I used an old two drawer file cabinet to mount it into. I placed a brick on the bottom of the cabinet and placed the rocket on top of it. That brought the top to the perfect height. I sealed it with some sheet metal and filled the whole box with perlite. I capped the perlite on top with some fire brick. That would boil a restaurant pan 3/4 full and shoot flames out the top of the riser and around the pan. Yehaaa!



Just a little more now. I built a shroud around the large pan I have and pushed the exhaust out the back and up some 6" flue pipe.

It will now give me a thriving rolling boil in the 2 sq ft pan with as much fluid as you want. You can see where it was getting too hot on the side of the shroud so I put a fire brick on each side to protect the sheet metal shroud. The shroud is set off the pan about an inch to inch and a half to keep the air flowing.


The best thing is it sips wood. Only the ends of the fuel burns and max is 6" wide so what used to require a full wood stove to operate now just the tips of the wood. It completely consumes every bit of fuel in the combustion chamber so no smoke or soot. Amazing! Still learning but I may try to expand the principals on a larger scale.

Next test burn I will get some pictures of it cranking!


Cant seem to attach pictures

"Use a water bath. A larger shallow pan that your syrup pan sits in, so that it has boiling water under it instead of the direct heat of the rocket stove. Most syrup operations use steam or boiling water to heat the syrup because if the syrup gets too much above the boiling point of water, it can carmelize."

This will work if you simply want to heat syrup but not effective for boiling sap. Even good sap requires a 40 to one ratio of sap to syrup so you need to boil off 40 gallons of water vapor to get your gallon of syrup.
I have also seen suggestions to set up some type of evaporator like a food dehydrator but the bacteria would eat all of the sugar out of the sap long before you would get to syrup at that low temperature.

My current set up is a 6" square steel tube as the stove. Insulating it was the only way to get enough heat out the top of the riser to boil large quantities of sap. My pan for this set up is a rectangle 12" by 24" and 8" deep. With this pan the most you can expect is 2 gallons of evaporation per hour. That is 10 hours for a gallon of sugar maple syrup. I plan to use this for finishing rather than quantity evaporation. My simple block arch will evaporate 10 gallons per hour but requires allot of fuel. My hope is develop a rocket fuel source for that some day.
The pan also needs to have a shroud around it directing the heat from the riser to the sides of the pan. If you do not do this the sides of the pan act as a heat sync and dissipates a substantial amount of heat, especially in colder weather.

Hope this helps a little bit so you can save some time on your project.

Hi. I'm back!

I have some photos to add.

Mod one was a basic j tube construction out of fire brick. This did not produce sufficient heat at the exit of the riser to boil large amounts of water.

Mod 2 would boil a pot but not the steam pan.

Mod 3 would boil the steam pan with a shroud around it but the real breakthrough was packing it in perlite. The temp at the exit point was a significant increase and the 1/4 inch steel plate will glow bright red during operation in the combustion area. I believe the higher temps help contribute to complete combustion leaving only small amounts of ash.


The cap on the loading chamber is not required for proper draft but forcing the air input through the bottom causes the flame to shoot out the top onto the pan base very efficiently.

One other option would be to use the j tube construction method but build the evaporator pan into the base of the j where the horizontal burn area produces the maximum output of heat.

Hi folks,
New to the forum but I have been experimenting with the rocket stove for maple sap evaporation and I thought I would share. Evaporation is a function of heat and surface area. About one gallon per hour per square foot of surface area if you have a good boil. More heat will give you the ability to boil a larger surface area.

So far I am on my 4th generation rocket stove. I have a pan that is two square feet of surface area and I am attempting to get a rolling boil in the entire pan. (Stainless steel 8" deep)

I have built the current manifestation with 6" square tubing and I built it into a two drawer filing cabinet filled with perlite. I angled the feed tube and added an air intake directly into the bottom. (Will try to post pic)

I have had good success with a restaurant pan at a good boil but I still need to build the shroud that will go around the correct pan.

My large evaporator is 24" by 60" and would require several stoves to get the necessary boil but we continue to experiment.

Spring is coming!

Have to run. Be back soon!