Reactors in Series and Parallel Questions and Answers

Answer: A

Both are true and the reason gives the advantage: a rate curve obtained directly from experiment can be used without ever fitting a functional form to it. The steps read off directly from the plot. No functional form is needed at all.

Answer: B

The stirred tank jumps the mixture past the slow start and the plug flow reactor finishes efficiently. This is the standard illustration of matching the reactor to the shape of the rate curve. The rate has an interior maximum here.

Answer: C

Parallel plug flow reactors with equal space times behave exactly as one, so nothing about the system changes. The other three all alter the mixing or the temperature history. Parallel plug flow behaves as one reactor.

Answer: D

Space times add for reactors in series, since the volumes add and the flow is the same through both. The conversion, by contrast, does not add and must be worked out stage by stage. Volumes add and the flow is common to both.

Answer: A

The first two are correct. The third is wrong, since parallel reactors share the feed and the system space time is the total volume over the total flow rather than the sum of the individual ones. Series and parallel behave quite differently here.

Answer: B

Several vessels give more surface area per unit volume and allow one to be taken out for maintenance. The capital cost is usually higher, so the choice rests on the operating advantages. Maintenance can proceed on one vessel at a time.