This set of Basic Chemical Engineering Multiple Choice Questions & Answers (MCQs) focuses on “Bypass and Purge”.
1. A bypass stream does not go through which of the following?
a) Mixer
b) Process
c) Separator
d) None of the mentioned
View answer
Explanation: A bypass stream directly goes from divider to separator skipping the process.
2. Which of the following does the purge stream comes from?
a) Feed stream
b) Product stream
c) Recycle stream
d) None of the mentioned
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Explanation: Purge stream is the removal of unwanted material from the recycle stream.
3. Which of the following composition can be controlled by a bypass stream?
a) Exit stream
b) Feed
c) Process
d) None of the mentioned
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Explanation: Bypass stream can be used to control the composition of a final stream.
4. Which of the following composition is controlled by purge stream?
a) Feed
b) Product stream
c) Recycle stream
d) None of the mentioned
View answer
Explanation: Composition of recycle stream can be controlled by purge stream.
5. Which of the following is decreased by the bypass stream?
a) Feed
b) Product
c) Feed & Product
d) None of the mentioned
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Explanation: Bypass stream decreases the feed and increases the product.
6. What is the required value of P to balance methane (CH4) in a process?
a) 5 mole/hr
b) 10 mole/hr
c) 15 mole/hr
d) 20 mole/hr
View answer
Explanation: Overall CH4 balance: 0.6*20 = 0.8*P, => P = 15 mole/hr.
7. In a certain process, what is the value of W when the system is balanced?
a) 5 mole/hr
b) 10 mole/hr
c) 20 mole/hr
d) 25 mole/hr
View answer
Explanation: Overall C2H6 balance: 0.4*20 = 0.2*15 + 1*W, => W = 5 mole/hr.
8. Given a material balance where G = 5 + H, and for CH4 balance, G(0.6) = H, what is the value of G?
a) 12.5 mole/hr
b) 25 mole/hr
c) 37.5 mole/hr
d) 50 mole/hr
View answer
Explanation: Material balance: G = 5 + H, CH4 balance: G(0.6) = H, solving both equations G = 12.5 mole/hr.
9. In a system where G = 12.5 mole/hr and for CH₄, H = 0.6G, what is the value of H?
a) 5 mole/hr
b) 7.5 mole/hr
c) 10 mole/hr
d) 12.5 mole/hr
View answer
Explanation: H = 0.6G = 7.5 mole/hr.
10. In a reaction where the total flow rate F is 20 mole/hr and G has been determined as 12.5 mole/hr, what is the value of B if B is given by B = F – G?
a) 7.5 mole/hr
b) 15 mole/hr
c) 20 mole/hr
d) 22.5 mole/hr
View answer
Explanation: B = F – G = 20 – 12.5 = 7.5 mole/hr.
11. For the reaction N2 + 3H2 -> 2NH3, where the overall conversion of N2 is 80% and the balance for W is given by 0.210 = 0.81*W, what is the value of W?
a) 2.5 mole
b) 5 mole
c) 9.5 mole
d) 20 mole
View answer
Explanation: 0.2*10 = 0.8*1*W, => W = 2.5 mole.
12. In a reaction where N2 + 3H2 -> 2NH3 and W = 2.5 mole, if F = W + P and F = 10 mole, what is the value of P?
a) 2.5 mole
b) 5 mole
c) 7.5 mole
d) 10 mole
View answer
Explanation: F = W + P, => 10 = 2.5 + P, => P = 7.5 mole.
13. For a reaction where the purge stream has an N2 balance calculated as 100.2 – 100.20.8 = 7.5x, what is the fraction of N2 in the purge stream?
a) 0.04
b) 0.05
c) 0.16
d) 0.4
View answer
Explanation: N2 balance: 10*0.2 – 10*0.2*0.8 = 7.5*x, => x = 0.05.
14. In a reaction system where the moles of H2 in the G stream are given as 100.8 – 3100.20.8 = 3.2 mole, and the moles of H2 in the P stream are 0.95*7.5 = 7.125 mole, what are the moles of H2 recycled?
a) 1.5
b) 2.2
c) 2.8
d) 3.9
View answer
Explanation: Moles of H2 in G stream = 10*0.8 – 3*10*0.2*0.8 = 3.2 = moles of H2 in H stream. Moles of H2 in P stream = 0.95*7.5 = 7.125, => moles of H2 in R stream = 7.125 – 3.2 = 3.925.
15. For the reaction N2 + 3H2 -> 2NH3, where recycled moles of H2 are 3.925 and recycled moles of N2 are 0.35, what is the value of R?
a) 1.4
b) 2.8
c) 4.2
d) 6.8
View answer
Explanation: Recycled moles of H2 = 3.925, recycled moles of N2 = (10*0.2 – 10*0.2*0.8) – 0.05 = 0.35, => R = 3.925 + 0.35 = 4.275.
Sanfoundry Global Education & Learning Series – Basic Chemical Engineering.
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