View Full Version : Rocket evaporator.
hansel
02-01-2017, 04:19 PM
Is the stove pipe a j tube burn chamber or the chimney? This will be my first year sugaring and I considered doing something similar with a barrel but was able to get a free 275 gallon oil tank in pretty good shape. Im going to use it on its side and plan on putting a firebrick rocket burn chamber on one end and see how many of the 4 stream pans will boil. I anticipate I will need a second rocket on the opposite end to get all 4 to boil. I just need to build my combo wood shed/sugar shack in the next week or 2 so I have a place to boil/hide the evaporator during offseason. The evaporator I figure will only take a few hours to make just being a few simple cuts on flat sections of the oil tank.
I have looked at rocket stoves. I think this is a cool idea for smaller producers. Hope it works. Keep us updated.
barnbc76
02-01-2017, 06:49 PM
I have a similar one, this will be the 3rd season. I used a galvanized trash can and stove pipe and a 16qt pot. It is a great preheater/boiler. I think It gives me about 3/4-1gal/hr. This year I upgraded it by placing a partial 55gal drum over top it so it will retain heat better. You will want to make sure you can get air under the fire somehow. This year I am going to dig a hole under it and put a grate across it. Also the more you use it and it starts to wear out you will want a rod under your pot to give it support.15287
Is your exaust going coming out the top? I see the stove pipe down at the bottom is that where the wood goes?
Shaggy acres
02-01-2017, 10:23 PM
I posted photos and a brief description on Permies.
The burn chamber and riser are now made out of fire brick because the 1/4" thick steel tube carbonized and chipped to pieces from the extreme heat.
https://permies.com/t/43160/Rocket-Stove-Maple-Syrup-Evaporator
barnbc76
02-02-2017, 09:32 PM
Looks good, how many taps are you going to do?
An overall mock up. This weekend, I will bring it outside. I'm going to fill it with sand and firebricks up past the bottom elbow. Then I'll use a bigger pipe (8") to wrap the (6") riser inside and add sand in between to insulate the riser then test fire it and see if it can boil water.
Sand isn't a great insulator I'd grab a bag of vermiculite or perlite.
5 Oaks
02-03-2017, 10:43 AM
My brother in law loves to build rocket stoves. He has been kicking around this idea. I don't dare show him this or he will not be a productive human for weeks until one has been built! LOL, so...how do i print this?! Thanks for the post, looks great!
barnbc76
02-03-2017, 07:33 PM
Now it make sense to me, very cool looks highly efficient, but is that going to be sufficient for boiling with 37 taps. I think you will be swimming in sap unless you have another thing to boil on in addition.
hansel
02-03-2017, 08:35 PM
I got it outside. Filled it with firebrick and Vermiculite and fired it up. My 8 " double wall riser blew apart when I was filling it with vermiculite. I will do without it for now.
15322
It works awesome so far.
15323
But........
15324
The burn chamber is cherry red.
I may be rebuilding it with firebrick sooner than I would like.
Yeah, you will probably burn through that stove pipe in just a few burns. I also imagine you don't need that much wood in there to maintain a boil.
hansel
02-04-2017, 09:55 PM
15337 my j tube will be like this. using 32 splits only need to make 2 cuts. will come in from underneath the tank make a rectangular cut 9 x 7. inside dimension is 4.5x6.5" which is very close to the area of a 6" circle. will mortar it in 2 pieces so i can clean out any ash, nails, etc. since i plan to burn mostly pallets, trash wood from the dump.
Joe Hillmann
02-23-2017, 07:51 PM
Because you are heating the sides of the pan as well as the bottom doesn't it burn once you get closer to syrup on the sides that are heated but not always covered in liquid?
hansel
02-23-2017, 09:51 PM
It's a nice design. But I think I'm going to try to go bigger than a 6" pipe size. I noticed as I was boiling that it was the rapid boiling was concentrated in that six area. Plus, it wasn't foaming too much. No need for a defoamer. But I was only getting a 2 gph boil rate.
15658
How many gph were you shooting for? Imagine that pot only has ~1.5 sq ft surface area. Could be some long days with 30 taps.
RollinsOrchards
02-23-2017, 11:09 PM
Not sure. Haven't got that far yet.
I would think that you could lift the pot partway out of the hole it sets in so that the heat only comes up the sides as high as the liquid level to minimize the burning on. We had a recessed flat pan and it did burn onto the sides a little, but not horribly.
Joe Hillmann
02-26-2017, 05:39 PM
I hate to say it but I don't think a rocket stove is the best option for long boils. They are meant to be very efficient at doing hot short fires but to keep one burning hot for 20-30 hours at a time would require you feeding it every couple minutes. I had thought of setting up some type of rocket stove but figured something that I can pack full of wood and coals was easier and with it being insulated much of the heat still ends up in the sap.
hansel
02-27-2017, 05:47 PM
After a bunch of tweaking. I got a decent setup. Once it gets hot. It's a rocket. But I'm noticing some limitations. One is, I have to sit here constantly feeding it. And once in a while you have to let the coals run down. Otherwise you either have to clean them out or the fire won't burn. Adds to downtime. My wood has to be small too. Real small.
15723
If I stuff it with long stuff. It gets clogged quickly. Which means I need to clean it out more often. Plus all that cutting leads to stuff like this happening.
15724
So yeah. Not sure if I'm totally sold on the rocket stove evaporator idea yet.
Your ratios look a little off: horizontal burn tube looks too long for that riser height. You may want to try it as an L instead of a J. If your burning longer stuff like lumber in your pic, you won't have to cut it as small and it should burn better. You will still have to push it forward though.
I saw your pan sitting in his shop the other day! How's it working out for you?
Trapper2
03-27-2017, 02:20 PM
Keep us informed on the updates. This is an most interesting thread as we can see your failures and successes.
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