(Solved): The figure above illustrates a distillation column applied in the production of acetaldehyde. In one ...

The figure above illustrates a distillation column applied in the production of acetaldehyde. In one figure, demonstrate a Piping & Instrumentation Diagram (P&ID) for this column by considering the following conditions. Please sketch back the figure for answering each a, b, and c. You need to have one sketch for each question.

a) The feed controller (FC11) regulates the feed flow rate to the tower. The reflux drum level is controlled by the reflux drum level controller (LC12) by adjusting the top product draw. The tower bottom level is controlled by the tower bottom level controller (LC11) by adjusting the bottom product draw. The overall material balance for the distillation column is maintained by these three controllers.

b) The product composition or the extent of separation is controlled by the bottom temperature controller (TC11). The bottom temperature is indicative of the bottom composition and is easier to measure and control than the composition. The tower bottom temperature is controlled by regulating the hot oil flow to the reboiler.

c) The tower pressure is regulated by the top pressure controller (PC11). This is a split range controller that operates on two valves, namely the condenser bypass valve (B) and the off-gas valve (A). If the column pressure is low, the condenser bypass valve opens to allow hot vapor from the column top to flow directly to the reflux drum. This raises the pressure. If the column pressure is high, the condenser bypass valve closes. If the pressure cannot be maintained by closing the bypass valve, the off-gas valve opens to release vapor to the flare header.