Which of the following composition can be controlled by a bypass stream? a) Exit stream b) Feed c) Process d) None of the mentioned
The correct answer and explanation is:
Correct Answer: a) Exit stream
Explanation (300 words):
In chemical and process engineering, a bypass stream refers to a portion of a flow that is diverted from the main process stream and redirected—typically around a unit operation—and then either recombined or discarded. The main purpose of a bypass stream is to control temperature, pressure, or composition in a system.
Among the options provided, the composition of the exit stream is what can most effectively be controlled by adjusting a bypass stream.
How it works:
Imagine a process where a feed stream goes into a reactor, and a bypass line diverts some portion of the feed around the reactor. The stream exiting the reactor will have undergone a chemical change (such as a reaction), whereas the bypassed stream will not. These two streams are then mixed to form the exit stream.
By adjusting the flow rate of the bypass stream, you can control the final composition of the exit stream. For instance:
- If you bypass more of the feed, less of the material is reacted, resulting in a higher concentration of reactants in the exit stream.
- If you bypass less, more material undergoes the reaction, and the exit stream has more product.
This method provides flexibility without altering the reactor conditions or feed composition.
Why not the other options?
- Feed: The bypass stream does not alter the feed composition—it only diverts a portion of it.
- Process: The term “process” is too broad and abstract; bypass streams do not generally control an entire process but rather a specific output or parameter.
- None of the mentioned: This is incorrect because the exit stream’s composition is affected.
Conclusion:
The correct answer is (a) Exit stream, as bypass streams are a valuable tool in controlling the final composition of what leaves a system.