The reflux column is the tube that runs straight up from the top of the boiler. The column is made from 2" copper tubing, is about three feet long, and has a thermometer mounted in the top cap. It is packed with Raschig rings (described later) to provide a large area condensation surface inside the column, and it has two cooling tubes that pass water through the vapors that rise through the column from the boiler. It also has a Tee connector at the top to accommodate an elbow connection to the condenser, and a screen at the bottom to keep the packing from falling out.
The column head section consists of a cap, a The Column Head thermometer, a 3" long nipple, and a 2 x 2 x 1 V2"
tee. It also includes a connection to the condenser assembly with two 1 1/2" x V2" nipples, and a 1 V2 x 1 V2" elbow. A drawing of the assembly is shown below:
The cap is drilled in the center with a 3/8" hole to fit a rubber grommet and the thermometer stem. Not all stems have the same diameter, so you should make sure the hole fits your thermometer. The cap is not soldered to the column. This is to allow the column and packing to be back flushed and cleaned out by simply taking off the cap and hosing down the column.
The column body is made of a 3 foot section of 2" copper pipe. It attaches to the 2 X 2 X 1 The Column Body y» Column Head Tee on the top, and to the boiler (or flange) on the bottom end.
Two 5/8" holes are drilled on the center-line of the pipe, through both sides of the center section of the column. The two holes should be about 18 1/2" O.C., but more importantly, they should match the upper and lower cooling tubes coming from the condenser. You should use a drill guide (or drill press) to insure that the holes are squarely in the center of the tube, and on the same line along its length.
When the holes have been drilled, clean up the top end and solder the Tee fitting, nipple, and the middle section together. Then install the 1 V2" nipples and elbow to the tee connection. Do not solder these yet. They must be left free for final fitting of the condenser assembly.
Line up the two 1 V2 X 1 V2 X V2" tees on the condenser with the cooling tube holes in the column body, and install two 7" lengths of V2" tubing through the column and into the condenser tees. You should have a tower assembly now that looks like this.
Make sure everything fits OK and aligns well. When you're satisfied, remove the cooling tubes and condenser. Clean up and solder the 1 V2" elbow and nipples to the column tee. Finally, re-install the cooling pipes to the condenser to assure its alignment, and solder the remaining joints.
The next task is to install the mounting flange or coupling to the bottom of the column, and cover it with a screen. There are a number of ways to do this, and in many cases, it will you have selected.
Attaching the column is much easier if the boiler has a removable top, but no matter how you decide to do it, make sure that you can easily detach the tower from the boiler for clean up.
The column should extend about an inch or two below the boiler cover so that brass screening can be used to cover the end. The screen keeps the tower packing (Raschig Rings) from falling into the boiler. A stainless steel hose clamp secures the screen to the bottom of the column.
The Tower Assembly
Mounting the Tower depend on what kind of boiler
A typical attachment under these conditions is shown below.
If your boiler doesn't have a removable top then you will not be able to use this method of assembling the column to the boiler.
The easiest alternative in that case is to have a short nipple of 2" copper tubing MIG welded to the top of the boiler. This will allow a union to be attached near the bottom of the column and allow the column to be removed at that point.
You will also have to install the screening at the bottom of the column in a different way so that the column pieces can be attached at the union joint. One approach is to solder a small mounting strap to the inside of the column, and attach a perforated sheet metal disk to the strap with a small sheet metal screw.
Because the boiler I selected has a removable top, there was no need to bolt and unbolt the column to clean it. You may do this though, to avoid MIG welding. I brought the cover and column down to a friend with a MIG welder. He cut the 2 1/8" hole in the cover, and welded the copper column to the stainless steel cap. It really looks pretty. I bought him a case of beer.
To wrap the construction phase up, the column has to be packed with something for the vapors to condense on as they pass up the tower from the boiler. There are a lot of things you can use to pack the tower. Recommendations range from marbles, glass beads, copper or stainless scrubbing pads, to broken automotive safety glass and others.
Packing is a poor word to use for this material. It implies a dense filler. What we really want inside the column is something that won't pack, burn, melt, dissolve, or release impurities or poisons into the vapor in the column. We also want that material to have as large a surface area as possible, and at the same time offer as little resistance to the gas flow as possible. It should be easy to clean, and above all, it should not settle or pack down in the column.
And while that is a pretty tall order, there is a product that satisfies all these requirements. The product is called Raschig Rings. They are tiny (about W diameter) hollow cylinders made of glazed ceramic material. They are perfect for this kind of tower. They look like this.
In any event, fill the tower with your packing to just above the top cooling tube. Put the cover cap on, and attach the cooling hose couplings with stainless hose clamps.
At this point the real construction is over. Your still is complete except for a few finishing details, like heating and cooling issues. We'll cover that next.
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