Walk-Through Qualification

Near the end of the semester, each new trainee is required to complete a unit walk-through with the instructor. During this process, a standardized checklist is used to record each student s level of competency. At the final exam, trainees are required to draw and identify each part of the pilot unit. These exams are typically extensive and require significant effort, since operational and troubleshooting data are included. The technical notebook reflects the sum of the student s efforts during the semester and is turned in on the last day. 

A pilot unit includes feed section, preheat system, distillation column, overhead system, bottom system, and product storage. The feed system is composed of a variety of equipment systems, including feed tank, valves, piping, instruments, and pumps. Before feed can be sent to the distillation column, it needs to be preheated using a heat exchanger. 

After the feed has been blended and preheated, it is sent to the distillation column. In a plate column, the heated feed enters on the feed tray. As the heated feed enters the column, part of it vaporizes and moves up the column. The heavier part of the mixture flows down the column through devices called downcomers. 

The overhead system is specifically designed to condense the lighter fractions and send them to product storage and back to the top tray in the column. The cooled, condensed product that flows back to the column is called reflux. The system is specifically designed to control product purity and control temperature in the top of the column. The overhead system includes a condenser, accumulator, pump, and piping. 

The bottom product is sent to the tank farm for storage. The overhead stream is sent to the tank farm, tested, and shipped to the customer. 

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