Distillation Mini Manual

DISTILLATION MINI MANUAL

Before you go to lab:

 Familiarize yourself with the software currently being used. The Lab view program that controls the column is pretty self explanatory. Flow rates, i.e. reflux and steam pressure are controlled on a numerical scale from 0 to 100. Increasing the value increases the flow incrementally. Temperature measurements are accurate within a degree or so but the steam pressure should be read directly from the column, behind the stairs. The Lab techs can assist in the use of the software they can answer questions on how to make the changes you want. We recommend talking with the lab techs for 15 min to have them show you the software so you are familiar before the first lab.  Familiarize yourself with the column before your first lab section by taking a trip to the lab. During this time period take a good look at the column, and the tanks that accompany it. Figure out how everything is connected to gain a basic understanding of the whole system. The vapor ports run down the back of the column and the liquid ports alternate on either side. Read through the Gas Chromatograph manual prior to your first lab. Proper technique is required for accuracy.  Make sure to inform the techs when you need the column to be running. The column takes approximately an hour to reach an initial steady state. If you forget to inform the techs, this will be an hour of wasted lab time.  Make sure to take a look at previous lab group results. Your assignment will often build off the results of previous groups.

During the lab period:

 The techs will turn on the column (if told to). It will be at total reflux when you enter the lab, make sure to turn the feed valve so that the feed goes to the column and not to the reboiler.  Assign one group member to run the Gas Chromatograph every day after the first sample is drawn. The GC is very time consuming. On the first day prepare a calibration curve for the GC samples, to relate area ratios to concentrations. The concentrations the GC fives are inaccurate. Paraffin every sample container to avoid methanol evaporation.  Set the feed tray at the desire plate (plate 4, 5, 7, 10, or 11 are available).  Occasionally the pneumatic valves will “stick”. This may require a brief step up followed by a step down in the set-point of that particular valve to free it up.  Turn on your feed, bottoms, and distillate rate. Adjust the steam and reflux rates as needed. Make sure that your feed in approximately equals your bottoms and distillate out (mass balance), otherwise the column will be run dry or start to accumulate.  Approximately every 20 minutes, visually monitor the separation through the view ports. Also pay attention to the reboiler level and the steam pressure value right underneath the ladder. The column will not necessarily stay at steady state, so don’t assume it will. Be careful to never run the reboiler or reflux tanks dry. The software will provide a warning you approach a safe limit; get a lab tech quickly to avoid shutdown.  If you need to measure steam quality leak steam into a well insulated securely closed container with the thermometer stuck inside. Be careful. It is easy to burn yourself at this step. The steam leaking is a constant enthalpy process.  At the end of the lab period, tell the techs that you are finished with the column. Don’t shut down the column on your own. You can turn the steam pressure off when you are done to help cool the lab.