Separation Processes Questions and Answers – Solid-liquid Cascades

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This set of Separation Processes Multiple Choice Questions & Answers (MCQs) focuses on “Solid-liquid Cascades”.

1. A material balance for any soluble material B around any interior stage from n=2 to N-1 is:
a) Y n+1 S + X n-1 RF A =Y n S + X n RF A
b) Y n+1 S + X n-2 RF A =Y n S + X n RF A
c) Y n+1 S + X n+1 RF A =Y n S + X n RF A
d) Y n+1 + X n-2 RF A =Y n S + X n RF A
View Answer

Answer: a
Explanation: Material balance for any soluble material B around any interior stage from n=2 to Y n+1 S + X n-1 RF A =Y n S + X n RF A Where Y j is the mass of solute per mass of solvent and F A is the mass flow rate of slurry and R is the constant ratio of mass of solvent to mass of insoluble solids.
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2. Which equation holds true at equilibrium?
a) Y N+1 = Y N
b) X N = Y N
c) F B = F A
d) R 1 =R 2
View Answer

Answer: b
Explanation: At equilibrium the concentration of B in each overflow equals the concentration of B in liquid part.

3. What is the formula for washing factor?
a) W= SRF A
b) W= RF A /S
c) W=SF A/R
d) W=S/RF A
View Answer

Answer: d
Explanation: The formula for washing factor is W=S/RF A, where F A is the mass flow rate of slurry and R is the constant ratio of mass of solvent to mass of insoluble solids.

4. The concentration of solute is given by:
a) (F B /S)(1/W Nsub>n-1 )
b) (F B S)(1/W sub>n-1 )
c) (F B /S)(1/W sub>n-1 )
d) (F B S)(W sub>n-1 )
View Answer

Answer: c
Explanation: The concentration of solute X N is given by (F B /S)(1/W sub>n-1 ) where S is the flow rate at stage N and F B is the mass flow rate of slurry and W is the washing factor.

5. What will be the concentration of solute in overflow doe N=2?
a) (F B /S)(1/W +1)
b) (F B /S)(1+W+W 2 /W 2 )
c) (F B /S)(1+W+W 2 /W)
d) (F B /S)(1+W/W 2 )
View Answer

Answer: a
Explanation: (F B /S)(1/W +1) is the equation used. Now for N=2, (F B /S)(1/W +1)= (F B /S)(1/W +1).
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6. Which of the following is true about cascades for a particular S?
a) Maximizes Y 1
b) Maximizes X N
c) Minimizes Y 1
d) Does not affect X N
View Answer

Answer: a
Explanation: The cascade for any given S, maximizes Y 1 , the amount of B dissolved in a solvent nleaving stage 1.

7. The minimum amount of solvent required is underflow ratio is 0.5 and insoluble solids feed rate is 2000Kg/hr is:
a) 2000kg/hr
b) 1000kg/hr
c) 4000kg/hr
d) 500kg/hr
View Answer

Answer: b
Explanation: S min =RF A , thus S min = 2ooo*0.5=1oookg/hr.

8. What is the washing factor if solvent feed rate is 3000kh/hr , underflow ratio is 0.5 and insoluble solids feed rate is 2000?
a) 2
b) 3
c) 4
d) 5
View Answer

Answer: b
Explanation: Since W= S/RFA , W= 3000/2000*0.5=3.

9. The minimum amount of solvent required is underflow ratio is 0.3 and insoluble solids feed rate is 200Kg/hr is:
a) 50kg/hr
b) 600kg/hr
c) 666.66kg/hr
d) 60kg/hr
View Answer

Answer: d
Explanation: S min =RF A , thus S min = 2oo*0.3=600kg/hr.
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10. What is the washing factor if solvent feed rate is 2500kh/hr , underflow ratio is 0.3 and insoluble solids feed rate is 500?
a) 13.33
b) 166.66
c) 16.66
d) 133.33
View Answer

Answer: c
Explanation: Since W= S/RFA , W= 2500/500*0.3=16.66.

11. What is the washing factor if solvent feed rate is 2500kh/hr , underflow ratio is 0.5 and insoluble solids feed rate is 2000?
a) 0.5
b) 1
c) 1.5
d) 2.5
View Answer

Answer: d
Explanation: Since W= S/RFA , W= 2500/1000*0.5=2.5.

12. What is the washing factor if solvent feed rate is 2800kh/hr , underflow ratio is 0.7 and insoluble solids feed rate is 2000?
a) 1
b) 2
c) 3
d) 4
View Answer

Answer: b
Explanation: Since W= S/RFA , W= 2800/2000*0.7=2.

13. What is the washing factor if solvent feed rate is 3000kh/hr , underflow ratio is 0.2 and insoluble solids feed rate is 10000?
a) 1
b) 2.5
c) 1.5
d) 4
View Answer

Answer:c
Explanation: Since W= S/RFA , W= 3000/10000*0.2=1.5.

14. What is the washing factor if solvent feed rate is 1000kh/hr , underflow ratio is 0.1 and insoluble solids feed rate is 10000?
a) 1
b) 2
c) 3
d) 4
View Answer

Answer: a
Explanation: Since W= S/RFA , W= 1000/10000*0.1=1.

15. What is the washing factor if solvent feed rate is 2300kh/hr , underflow ratio is 0.3 and insoluble solids feed rate is 2000?
a) 1.97
b) 2.33
c) 3.07
d) 3.83
View Answer

Answer: c
Explanation: Since W= S/RFA , W= 2300/2000*0.3=3.83.
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Manish Bhojasia, a technology veteran with 20+ years @ Cisco & Wipro, is Founder and CTO at Sanfoundry. He is Linux Kernel Developer & SAN Architect and is passionate about competency developments in these areas. He lives in Bangalore and delivers focused training sessions to IT professionals in Linux Kernel, Linux Debugging, Linux Device Drivers, Linux Networking, Linux Storage, Advanced C Programming, SAN Storage Technologies, SCSI Internals & Storage Protocols such as iSCSI & Fiber Channel. Stay connected with him @ LinkedIn