Air cooled design feedback needed

[ecgoeken]

This is going to be my first build. After doing some research I think I would like to build an air cooled design. I am going to be operating this in an area with no access to running water. I know that I could use a pump and a bucket of ice water to condense, but I'd rather not deal with the hassle. Plus, I like to try new things. This is why I want to try this experimental build. I would like any advice as to whether or not you think this design will work. I would like to get as high an ABV as possible in one run. I am going to build a relatively small still using a turkey fryer for the boiler. I want to add fins to the copper column to dissipate heat and continually return reflux along the length of the scrubber packed column. On top of my column will be the thermometer to measure which vapors have made it past the column. Those vapors are fed into a .25" copper coil encased in an open ended pvc pipe with a fan on top. This would in effect create a wind tunnel across the copper condensing coil. After this stage I would collect the bounty. Building the column will take some effort so I would like to get some feedback before I jump into this build. I did a quick sketch of my idea. Please forgive the quality. I had to take a picture of the drawing with my phone. lol Thanks for your comments

http://i1163.photobucket.com/albums/q55 ... 1348178881" onclick="window.open(this.href);return false;" rel="nofollow

[NcHooch]

It's generally recognized that 3/8" tubing is the minimum to be used for a condenser coil. How do you plan on controlling the reflux?

I gotta tell ya, if I was going to build an air-cooled still, I'd be using a section of hot-water baseboard.

[Prairiepiss]

I would consider a worm in a bucket for a condenser. You don't need running water for that.

[ecgoeken]

The thought was that the fins along the entire length of the column would dissipate heat from the vapors and continuously create reflux. thats the thought anyways...

[Prairiepiss]

The problem would ne you want the reflux to come from the top. And the column to hold a natural temp gradient from bottom to top. If your cooling the whole length it will hamper its abilities to do that. And you really have no control over it. Air cooled wouldn't be the way I would go. But there are a few examples of what others have done around here. Some have worked some haven't. And some just look like death traps.

[CrickShine]

I have an air cooled reflux still, 2 inch column, 4 feet high, almost entirely packed with copper mesh. At the top is a 3/8th inch short reflux condenser that just goes up makes 3 loops and back down to the top of the column - this just adds another step to the reflux. Then just down from the top is the real condensor take-off with a needle valve. Mine is made from 1/4 inch flexible copper tubing. Originally, I took a 50 foot coil and wound it around a coffee can and then stretched it out to match my comlumn height. It did a great job of cooling but I did not need that much length - temp in the garage is usually 65 degrees F. The trouble I had that it created a lot of operating pressure and I had to seal my boiler really tight and then all the joints needed to be monitored continuously. So I shortend the condensor lenth to about 25 feet and it still works good. If it starts to spew vapor I run a small fan acoss it for a minute and then is works again (usually if it spews vapor I need to turn down my heat on the boiler).

If I was starting from scratch - I would use 3/8 tubing instead of 1/4. Also, you will not like the affect of the fins on the column. You need the column to be hot all the way up and then dissipate the heat in a reflux condensor. Actually, my first run was without the reflux condensor and it worked fine - but you got to keep messin with the design or your not having fun.

Crickshine - the weather is great in Washington

[myles]

There is actually lots of info on air cooled stills if you look. Your finned tube is good but it should be used on the reflux condenser chamber, not on the column itself. The column should be insulated. As for the forced air ventilated product condenser - yes that will work just fine, but as has been said, increase the size of the tube.

Riku has done a lot of work on these, and as a guide 2x 1m lengths of convector pipe (your vanned tube) will make an air cooled reflux condenser that will cope with about 1kW. As you can see these are lower power devices because of the relatively poor efficiency of the air cooled reflux condenser.

[Maritimer]

I'm a newbie, doing my second run right now. What really surprised me was how much heat the condenser has to take away. If you are running the boiler at 2 kW, the condenser has to take away 2 kW of heat. If you've used an electric heater, you might know that 2 kW is a lot of heat. Imagine getting rid of that heat and cooling the condenser down enough to keep the temperature low enough to condense the hot vapour around it.

Instead of going directly to air, you can go to water, and then cool the water in a radiator. Here is the solution I came up with:

The radiator is actually a condenser from a car air conditioner. The scrap yard had a wide choice, but this one looked ideal. Inside the box are two 16 inch oscillating table fans which I disassembled and attached to a piece of plywood in the bottom of the box. You can feel the heat difference between the upper long edge of the radiator (where the hot water comes in) and the lower edge (where the cool water comes out).

Here is a close-up of the radiator fins:

The amount of fins required is enormous. This is the point I'm making: you will need a lot more fins than you might think.

M

[kobold]

maybe a duh question, but did you look at the air still? its design is both compact and simple, might give you some ideas.

[UnseatedPanic]

Ok not to bring this up and not to be the ass of the group ... but please tell me you are not running the stuff you drink though an old car radiator... you know they make those with lead solder.... and have had antifreeze in them.... because if you are you are going to posion yourself even if itd new still made with lead...

[myles]

Ok not to bring this up and not to be the ass of the group ... but please tell me you are not running the stuff you drink though an old car radiator... you know they make those with lead solder.... and have had antifreeze in them.... because if you are you are going to posion yourself even if itd new still made with lead...

It does say quite clearly "hot water in....cold water out". As a coolant radiator it is just fine. But the point was well made. Do not run your product through an old radiator.

[sambedded]

Those vapors are fed into a .25" copper coil encased in an open ended pvc pipe with a fan on top. This would in effect create a wind tunnel across the copper condensing coil.

Yes 1/4 for coil is to small. And I would install fan at the bottom to avoid it's overheating.
On what power level are you going to run your column?

[myles]

Here is a bit of guidance to start you off. A 5m long length of 10mm tube in a coil can condense about 300w. Put that in a length of 5" or so drainpipe with a computer fan, and it will handle about 1kW.
Pintoshine runs a bigger version with 60 foot of 1/2" tube and a bigger fan, that will cope with 2.2kW and produce just less than 1 gallon / hour.

An air cooled product condenser is very viable. I ran a liebig on air one winter some time ago and that worked too.

With a minimum of 3/8" tube you could probably also make a force cooled reflux condenser, have a look at spiral stills just for a bit of an idea. They are typically very low power (300w), but with forced cooling this could be improved on.

[sambedded]

Sample of 3KW air-cooling design - http://translate.google.ca/translate?sl ... .0&act=url" onclick="window.open(this.href);return false;" rel="nofollow