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TSilly
03-29-2014, 11:04 PM
Hello,

Last year I did a barrel stove evaporator and had lots of fun boiling off for the first time ever! This year I decided to increase the size of my evaporator because most often I only have time after work and last year that meant boiling until 2am or later. I decided I needed a better tool. After looking around, seeing lots of options, then fine tuning the design planning with these forums I've built my new oil tank evaporator. I 'finished' it today (though it's raining cats-n-dogs outside so I can't test it!) and will hopefully fire it up soon!

Things I thought about:
Maximizing surface area -- I had hope to have 6 full pans on top for a full 10 sq ft of evaporation space but because of shape of the tank and pans there were some limitations so I went with 4 x 4" water steam pans and one large pan in the front that I found at a used kitchen supply locally. Each of the 4 pans is about 12" x 20" = 240 sq in or 960 sq in. The front pan is 15" x 25" = 375 sq in. Together this is right around 9 sq ft which as the rough rule-of-thumb is about 9 gallons/hr.
I built the fire box to work with a rocket stove but wanted to be able to have it be a "normal" firebox as well. My first phase is starting with the rocket stove but eventually will use a combination of perlite/chimney cement to create a high temperature insulation for the firebox, add a grate, and try out burning full logs. If you aren't familiar with rocket stoves all you need is a few minutes on YouTube to help get an idea of what they are about.
Trying to use as much "gathered" items as possible. I also really aimed to maximize using as much of a given object, especially the oil tank so I didn't need to seek additional materials
So far materials worked out like this:
- Used (surplus at local metal shop, Craigslist, Local hardware store): 1/4" 8 in square tubing for rocket stove, perlite/refractory cement, millions of cutting wheels, spool of flux core wire, chimney pipe
- Free (Freecycle, friends, family, Facebook) - oil tank, angle iron, bed frames (more angle iron), steel pipe, borrowed welder

Here are the pictures:
Back view 9501 -- Stack with bucket for preheating in the space before stack
Front view 9502 -- 4 Steam table water pans (slight larger than a full size), one oversize pan (15" x 25")
Front view, pans removed 9503
Video walk through
http://youtu.be/pdzP255fDno

Enjoy!

Cheers - Tom in Leeds, MA

optionguru
03-30-2014, 07:51 AM
I can't get the pics to load but the video looks good. I can't believe how many pans you were able to fit, now I have a new challenge for the off season. Looks great, I think you may get an even better evaporation rate with the sides of your pans being down in the fire. Gives you a lot more surface area exposed to the fire. Good luck, keep us updated.

TSilly
03-30-2014, 11:07 PM
Pete - I think you are right that I could have the rocket stove stack come a lot closer to the front pan simply by shortening the legs.

I did fire the evaporator with water in the pans today. Here is what I have found so far:
1. I started with a 4' stack but quickly moved to an 8' stack and that made a big difference in keeping the draft pulling!
2. The blower is great but makes stuff so hot that I melted my asphalt driveway (hopefully I can remove it tomorrow, yikes!) I will take this as an opportunity to insulate the stove around the firebox to prevent melting the driveway and making sure as much heat as possible is going straight up the rock stove chimney to the first pan.
3. The front door has a huge gap as it was just put together quickly but when running the blower it pushes so much air that it forces heat/ash through the front door. I will seal the front door with a layer of insulation and the original cut out to keep heat in and prevent the blowing out.
4. I am putting a plate that can adjust the intake on the blower to reduce the CFMs and therefore can adjust the blower better.
5. Insulation (which was going to happen once I knew whether I needed to re-weld anything) will go in to the firebox area and along the "table" (under the four pans) to again make sure I am heating up what I would like to.
6. I may eventually put a baffle in the back area to force the hot gases to better heat the pre-heat bucket better as right now the gases are rushing by the top 2 inches and heating it from the top down. If I take the sq in of the output chimney (~ 28 sq in) then divide by the height of the back box (10") and divide by 2 (so the gap will be divided for each side of the bucket it would give me a baffle with approximately 1.5" on either side which should hopefully force the hot air to move further down the side of the buckets..

I hope to get insulation and a couple of these tweaks done and may do a test and transition to a evaporation if all goes well!

TSilly
03-31-2014, 05:38 PM
It seems others couldn't see my pictures so here is a repost:

http://img.tapatalk.com/d/14/04/01/9y2ury7u.jpg
http://img.tapatalk.com/d/14/04/01/mysery9u.jpghttp://img.tapatalk.com/d/14/04/01/u9a3u8es.jpg


Sent from my iPhone using Tapatalk

Peabbles
03-09-2017, 11:40 AM
Tom, are you still using this rocket evaporator setup? This is my second year using an institutional rocket stove. I've been through several iterations with the burn chamber. Originally built with stove pipe, that disintegrated after 2 runs. 1/8" steel pipe lasted 13 runs. Now I'm experimenting with insulated castable refractory but I haven't found a mix that doesn't crack up. Anyway the pot is 60L and I can get approx 2.5gal/hr evaporation, but I've been thinking about attempting something like you've done to increase the evaporation rate, but I still would like to keep the wood use to a minimum.

Post an update if you have some time. I'd love to know more about how this worked out for you.