Still Operation and Checkout
Using this still involves working with heat, steam, electricity, gas, and possibly explosive vapors. You must take extreme care to prevent injury, fire, or explosion if you ever decide to use the device.
Some view using it to distill alcohol as being akin to boiling gasoline on your home gas or electric stove. Over time more than one person has been maimed or killed in the explosions and fires resulting from these activities. You must be careful at every step in these procedures.
In this section we will be going over how to operate the still for the first time. Before you use the still for any purpose, test the apparatus by distilling a gallon or two of water. This preliminary run will verify that the joints don't leak, that there is sufficient heat input to do the job, and that there is enough cooling to control the distillation. It will also help clean up any remaining flux from the joints soldered during construction.
The Internal Reflux Still
To start the run, mount the boiler on top of the heat source, fill it with about a gallon of tap water, and attach the column to the boiler. Then connect the cooling hoses on the column to the water supply and drain.
Do not allow the cooling water to circulate through the apparatus at this time.
Turn on the heat to its highest setting and insert the thermometer in the top of the column. The bulb should be seated to the level of the upper column tee connection (where the vapors flow to the condenser).
In a short time (about 10 or 15 minutes depending on the heat source) the water should be boiling to the point where both vapor and liquid can be seen exiting the condenser. The thermometer should indicate that the boiling point temperature (100° C.) has been reached in the column.
The next step should be to determine the maximum distillation rate of the still. To do this you will need to open the cooling flow to the maximum and increase the boiling rate to the point where the condenser can no longer condense all the vapor.
It's easy to recognize this point because you'll be able to see a lot of steam mixed in with the distillate running from the still.
When you've reached that point slowly back down the heat to the point where the vapors no longer exit the condenser. In doing this, be careful not to reduce the heat to the point that the thermometer drops below the boiling point (100° C.). You should now be at the maximum distillation rate settings for this still.
When you have reached that point, measure the time needed to collect exactly 250 ml of distillate.
Knowing the maximum distillation rate is important because it forms the basis for estimating the reflux flow. Recognize though, that in this exercise we are working with water. Different mixtures in the pot will have different distillation temperatures and different rates of distillate flow. You will need to redo this exercise to get the right basis figures for the distillation at hand.
Before finishing up the initial run you might find it worthwhile to time and measure a few distillate volume readings at different cooling settings to get a feel for the control sensitivity and distillation rates. Finally distill about a gallon of water to finish cleaning out the still.
When it's time to shut the internal reflux system down you should always follow a set sequence of actions in order to avoid problems. The shutdown sequence is:
1. First remove the thermometer cap from the top of the column.
Use gloves, it may be hot.
2. Next turn off the heat.
3. Finally shut off the cooling water circulation.
This is important, because if you are using plastic tubing to collect the distillate from the condenser, it could get kinked or obstructed in some way. That would seal off the apparatus from the air. If this happened while it was cooling down, a vacuum would be formed within the still as the vapors inside condense, and the air pressure outside could crush the unit.
When the unit has reached room temperature, disconnect the cooling hoses, and back-flush the column with water. Then remove the cover and clean and flush the boiler.
Valved Reflux Still
Operating the valved reflux still is much easier than running the Internal Reflux still because the valves on the still head provide direct control of the distillation and reflux rate.
As with the Internal Reflux checkout run, you should begin the checkout run by filling the boiler with a gallon or two of water.
Next install and bolt down the top end with the keg clamp screws, close both needle valves on the still head, and connect up the cooling hoses. Then install the thermometer in the column cap.
At this point you should turn on the heat at high setting to bring the water to boil, and also turn on the water circulation,
The temperature will rise to 100° C. when the boiling starts, and steam will begin to appear at the top of the still head. When this happens, turn down the heat just enough to stop the vapors from escaping but without changing the temperature as measured by the thermometer.
When you have reached this state, the water will still be boiling, but all the vapors are being condensed at the coil in the still head. The condensed distillate will then run down the still head and collect in the valved cap and nipple at the bottom of the assembly.
Opening the collection valve at this time will allow you to measure the distillation rate without any reflux (max distillation rate). As with the Internal Reflux instructions above, measure how long it takes to collect 250 ml of distillate.
Once the max rate has been determined, you can then close the output valve and open the reflux valve. The system will then be operating in total reflux (all distillate is returned to the column).
Finally, after running under total reflux for a few minutes, adjust the output valve to allow a collection rate of about 1/3 of the maximum rate. That will mean that about 2/3 of the distillate will be flowing back into the column for re-distillation, and the other 1/3 will be collected as output.
At this time you might also experiment with adjusting the reflux valve at this point to increase or decrease the amount of distillate returned to the column or retained in the holding cap,
After you‘ve become comfortable with the operating controls shut down and clean up the system.
The valved reflux still water and heat connections can be shut down in any order without any danger of implosion because the column is always vented to the air at the top of the still head.
Nevertheless, it is good practice to first remove the column cap and thermometer (use gloves ). This will help to protect accidentally breaking the thermometer when removing the column from the boiler.
Also, please be careful in dealing with the near boiling water remaining in the boiler, and with disconnecting the heating supply (both electric and gas).
After disconnecting the water hoses you can then remove the top end from the boiler for cleanup.
Now that you know how to run the still, it might be a good idea to give some more thought of how to tune it so you can get the most out of using it. That's next.