The distillate stream from a distillation column (flowrate \(35 \mathrm{~m}^{3} / \mathrm{h}\), density of water) is recycled. The destination of the recycle stream is at a location \(3 \mathrm{~m}\) below the fluid level in the reflux drum. First, the recycle passes through a pump to supply sufficient head to overcome frictional losses \((20 \mathrm{kPa})\) and reach the pressure of the stream with which it is mixed \((250 \mathrm{kPa}\) above distillate stream). Then it is heated from \(90^{\circ} \mathrm{C}\) to \(120^{\circ} \mathrm{C}\) using low-pressure steam at \(140^{\circ} \mathrm{C}\). Assume that all resistance is on the process-stream side of the exchanger (tube side).

It is desired to scale up the entire plant capacity by \(15 \%\). It has been determined that the distillation column can be modified to maintain the recycle stream temperature at \(90^{\circ} \mathrm{C}\). It has also been determined that, with the required changes in the feed section of the process, the minimum temperature of the recycle stream must be between \(119^{\circ} \mathrm{C}\) and \(121^{\circ} \mathrm{C}\) to satisfy liquidphase reactor inlet conditions after mixing with fresh feed.

a. Can the temperature criterion be satisfied?

b. Can the flows in this portion of the process be scaled up by \(15 \%\) ? The pump curve is in Figure P22.19.

c. With a scale-up of \(15 \%\) desired, what feature must be included in this distillation column so that column operation can be modified to maintain the recycle stream at \(90^{\circ} \mathrm{C}\) ?

d. It is suggested that because a lower temperature of the recycle stream would reduce the reaction rate, if needed, the pumps in the feed section could be used to increase the reactor pressure and hence the reaction rate. What is your opinion of this suggestion?

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Pressure Change (kPa) 400 350 300 250 200 150 0 10 20 30 Volumetric Flowrate (m/h) 40 50