The condenser for this distillation column is a shell-and-tube heat exchanger containing 19 tubes and a glass shell. This heat exchanger is tilted horizontally towards the exit for a smoother flow of the condensate liquid. The cooling water comes in from the vapour side, flows through half of the tube bundle to the opposite end and then returns to exit at the inlet side. A flow controller on the operation software controls the cooling water flow rate and two temperature sensors measure the inlet and outlet temperatures of the cooling water. Note that vapour coming from the distillation column condenses on the outside surface of the horizontal tubes, and vapour condensation should be complete by no more than 2/3 of the condenser length to ensure safe operation, as is the norm for distillation condenser design. If the vapour goes beyond the limit and escapes from the condenser, a temperature sensor at the condenser vent will detect the rising temperature. If the vent temperature reaches 40 degrees Celsius, the safety threshold, the operation software will shut off the operation. This is just one of the control mechanisms to ensure safe operation. As can be seen, the pressure drop in the condenser should be negligible because of its sheer size, meaning that the pressure in the condenser is almost the same as that at the top of the distillation column. As such, the column pressure is also commonly used to control the safe operation of a distillation column.
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