Shut Down Procedure

The pilot plant should be safely and efficiently shut-down at the end of every trial run. Under no circumstances should the feed pump or reboiler be left operational overnight or while the pilot plant is unattended. A shut-down procedure is outlined in Table 12.10 and, jgain. common sense and safety should be the primary focus at all times.

If necessary, a faster shut-down can be achieved by withdrawing distillate and collecting it in the product cylinders as either liquid or vapour. This action will reduce the column pressure and initiate rapid cooling as liquid vaporises throughout the column. However, this shut-down route potentially wastes hydrocarbon since it is difficult to recycle the distillate from the product cylinders.

Table 12.10 - Normal Shut-Down Procédure for the Réactivé Distillation Pilot Plant

Step

Action Required

1

Turn the reboiler off. Continue to circulate chilled water through the condenser and the bottoms cooler. Continue to manipulate the bottoms control valve to keep the reboiler sump level stable.

2

Shut the distillate control valve as the column pressure begins to decrease. The reflux control valve can remain open.

3

Continue to recycle the bottoms product to the feed tank via the bottoms cooler. This will remove heat from the process and expedite the cooling of the equipment.

4

Stop the feed pump and close the bottoms control valve when the reboiler temperature falls below 60°C.

5

Stop the chilled water flow to the condenser and bottoms cooler and allow the column to cool further due to heat losses only.

6

Turn off power to the reboiler and feed pump but maintain power to the thermocouple display to provide a continuous indication of the temperature of the column.

7

Check the orientation of all ball valves to ensure that all sample points are closed and that the column is isolated.

8

Stop the extraction fan and air conditioning once the laboratory atmosphere is normal. Continue to circulate air through the laboratory (via the extraction fan and air conditioning) if a strong hydrocarbon or ethanol odour is detected.

Was this article helpful?

+1 0

Post a comment