Operational Considerations
For the sub-teams that performed the experimentation, early in the semester, several operational issues were encountered. In order to obtain reliable experimental data and ease the experimentation for teams yet to perform the experiment, the following key operational issues were addressed during the experimentation.
Due to the inherently high flow rates of the bottoms pump, it was noted that the column could not achieve steady state condtions below certain feed flow rates. During first trial of experimentation for one sub-team, the chosen feed flow rate was so low that the bottoms pump could not be utilized to create steady state conditions. In turn, the data obtained during this trial could not be used to achieve the objectives because steady state conditions might not have been reached. Thus, a lower limit of the operating feed flow rate was created to prevent irrelavent data.
Reflux Preheaters
During the course of experimentation, the reflux preheaters had to be operated at the maximum setting in order to obtain the desired reflux temperature. One team tried to achieve the desired temperature by increasing the reflux pump setting; however, the temperature could not be obtained in that matter, so the alternative was to set the reflux preheaters on the maximum setting.
During the experimentation of one sub-team, the reboiler was set on the maximum setting at the beginning of the experimentation resulting in a steady flow of condensate. During the course of the experimentation, the reboiler temperature was reduced. After about five minutes of running the reboiler at the lower temperature, the sub-team noticed that the flow of condensate was considerably reduced. As a result of lowering the reboiler temperature, the amount of energy supplied to the reboiler was not sufficient to produce enough vapors to travel to the condenser. Because there was no condensation occurring along the condenser coils, the experiment was restarted with the reboiler temperature on the maximum setting. Therefore, it was deduced that the reboiler should be kept on the maximum setting.
On day three of experimentation for one sub-team, the rubber ring around the top of the feed tank came off and fell into the tank. The laboratory engineer, Mr. Crisler, was immediately notified, and he retrieved the ring using a long piece of sturdy wire. Some of the ring had dissolved in the feed solution and black specs could be seen floating in the tank. To ensure that the feed had not been contaminated to the point of interfering with the results, the black specs were removed and the solution was stirred, and then a sample of the feed was taken and run through the GC for analysis. The resulting chromatogram showed no contamination, and the only components present were ethanol and n-propanol.