Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Separation Processes > week 4 > Flashcards

week 4 Flashcards

1
Q

Distillation method used for low volume high value products

A

batch distillation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Two types of batch distillation

A
  1. Differential distillation
  2. Batch rectification
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Batch rectification has two modes of operation

A
  • constant product composition
  • constant reflux ratio
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

As material is withdrawn, the MVC composition becomes smaller

A

Constant Product Composition

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

To maintain a constant product composition, the reflux ratio must be ____ as the composition of the MVC decreases

A

Increased

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

To maintain a constant product composition, the _____ must be increased as the composition of the MVC decreases

A

Reflux ratio

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Material balance of constant product composition

A

𝑆1𝑥𝑠1 − 𝑆2𝑥𝑠2 = 𝐷𝑏𝑥𝑑

S1 = mols in still initially
S2 = mols I’m still after
xs1 = mol frac of MVC in still initially
xs2 = mol frac of MVC in still after

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Equation for amount of product obtained in constant product composition

A

𝑆1 − 𝑆2 = 𝐷𝑏
S1 = mols in still initially
S2 = mols I’m still after

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

MVC

A

Most volatile component

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

If a column is operated at _____, the composition of MVC will continuously fall

A

Constant reflux

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

If a column is operated at constant reflux, the composition of MVC will continuously ___

A

Fall

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Constant product composition reflux ratio equation

A

dLb/dDb

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Most expensive type of tray arrangement

A

Bubble cap trays

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Tray arrangements from highest relative cost to lowest

A
  1. Bubble-cap
  2. Valve
  3. Sieve (lowest)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Tray arrangements from highest pressure drop to lowest pressure drop

A
  1. Bubble cap (highest)
  2. Valve
  3. Sieve (lowest)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Which tray arrangement has the lowest efficiency?

A

Sieve tray

17
Q

Which tray arrangement has the lowest vapour capacity?

A

bubble cap trays

18
Q

3 Tray arrangements

A
  • Sieve trays
  • Valve trays
  • Bubble cap trays
19
Q

Typical turndown ratio of a sieve tray

A

2

20
Q

Typical turndown ratio of a valve tray

A

4

21
Q

Typical turndown ratio of a bubble cap tray

A

5

22
Q

indicates the range of flow that is able to be measured with acceptable accuracy

A

Turndown ratio

https://en.wikipedia.org/wiki/Turndown_ratio

23
Q

3 types of reboilers

A
  • Kettle type reboiler
  • Vertical thermosyphon reboiler (reboiler liquid withdrawn from bottom sump)
  • Vertical thermosyphon-type reboiler (reboiler liquid withdrawn from bottom tray downcomer)
24
Q

Possible vapour liquid flow regimes for a contacting tray

A
  1. Spray
  2. Froth
  3. Emulsion
  4. Bubble
  5. Cellular foam
25
Q

Overall Column Efficiency equation

A

E = number of ideal stages/actual number of stages x 100

Values of E tend to vary between 30-100%

26
Q

Factors affecting column efficiency

A
  1. Kinetics slow as you near equilibrium
  2. Factors related to plate design
27
Q

measures performance of a single tray by considering the composition of the vapour phase as it enters and leaves a given tray

A

Murphree Efficiency

https://neutrium.net/equipment/distillation-tray-efficiency/

28
Q

Murphree efficiency equation

A

(yn - yn-1)/(ye - yn)

yn = vapour mol fraction on plate n
yn-1 = vapour mol fraction on plate n-1
ye = vapour mol fraction that is in equilibrium with the liquid mol fraction

29
Q

For a single plate, the vapour leaving is in equilibrium with the liquid leaving, and the ratio of that actual composition achieved to that which could occur if equilibrium between yn and xn were achieved is known as…

A

Murphree plate efficiency

30
Q

Shown by the lowest point on the total cost line

A

min total cost

31
Q

McCable Thiele Plots with a single side stream have

A

2 top operating lines with slope Ls/Vs and Ln/Vn

32
Q

McCable Thiele Plot for a distillation column with two feeds has…

A

An operating line per section (3)
A q line per feed (2)

33
Q

Overall column efficiency

A

E = (number of ideal plates/ actual number of stages) * 100

34
Q

Factors related this are

A
  1. Kinetics slow as you near equilibrium
  2. Factors related to plate design

Separation Processes (6 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions