Separation Processes Flashcards
Ideal or Perfect Leaching
No inert is included in the extract
LEACHING
Composition of
1. Solution
2. Underflow
- Solution = Solute + Solvent
- Underflow = Solution + Inert
Underflow = Liquid + Solid
LEACHING
Constant Solution Retention
R = M sol’n / M inert
x or y = M solute / M sol’n
LEACHING
Equilibrium
y1 = x1
LEACHING
Tiller-Tour Equation
Determination of Stages
. log (x1 - y2 / xN - yN+1)
N = ————————————- +1
log (x1 - xN / y2 - yN+1)
Remember to add 1
Vertical X and Y
1 2 N, and N add 1.
Horizontal X and Y.
Swap XN, Y. and add 1.
LEACHING
y2
Determination of Stages
y2 = L/V (x1 - xN) + yN+1
Yellow two, length over velocity. Removen the Xs and add the Y with one side chick.
LEACHING
Efficiency
N, theo
η = ———————
N, actual
Always round N off to a whole number
LEACHING
Mass fraction of the solute in the extract in a constant solvent retention means
x or y = M solute / M solvent
it is not y1
MASS RATIO:
ex. mass fraction is …. 0.6; x1=y1=0.6V1/04.V1
LEACHING
- Counter-current
- Co-current
Leaching
(1)
V1 ←| |← V2
L0 →| |→ L1
(2)
S
↓
F →| |→ L
↓
V
V = y ; Extract
L = x ; Raffinate
LEACHING
When solving, always start with
Equilibrium: y1 = x1
-> a/V1 = F, solute - a/L1
Inert as basis if Retention is given and no feed amount is mentioned
Applicable in Counter current and Co-current systems
Rose oil is extracted from rose leaves using _____ distillation
Steam Distillation
When the solvent dissolves very little of solute then
large quantity of solvent is required to extract the solute
An ideal single stage extraction process is used to treat 100 mol/s of an organic feed solution. The solute concentration in this solution is to be reduced from 0.5 mol% to 0.1 mol%. A pure solvent S is used. To reduce the solvent requirement by half for the same separation
use another pure solvent S* whose partition coefficient is twice that of S
The triangle whose one corner coincides with the enriching line and the outer corner is on the stripping line is called the
Feed Plate
Flash distillation is suitable for the separation of components
having very wide boiling points.
Relative volatility varies with the concentration of component for an ideal solution. The relative volatity of a binary mixture may be defined as the ratio of vapor pressure of component ‘A’ to that of component ‘B’, when
vapor phase obeys Dalton’s law and liquid phase obeys Raoult’s law.
Leaching of coarse solid lumps is also termed as
Percolation
Large scale usage of flash distillation is practiced in
petroleum refinning
In an operating distillation column, the
driving force for the vapor flow is the pressure drop, as the pressure decreases gradually from the bottom to the top of the column.
In case of steam distillation, the steam leaving the liquid is not completely saturated with distillate vapor, because
mixing of steam with the material being vaporised is not so intimate as to result in equilibrium condition.
For a binary mixture distillation process, the degree of freedom is 2. However, if the pressure is fixed in this process, the number of independent variables in this process will be
1
Partition Ratio if:
1. kD > 1
2. kD < 1
- kD > 1; E/R
- kD < 1; R/E
ex. Y = 2.2 X —> CE = 2.2 CR (kD=2.2)
LLE
Shortcut Formula in getting solute A (in Raffinate) in a single/multiple stage extraction.
A,Rn = A,F (B / kD·S + B)^n
Rec = 1 - A,Rn/A,F
Rn = Raffinate in nth (last) extractor
Rec in extract
LLE
Shortcut Formula in getting solute A (in Extract) in a single stage extraction.
(Partition Ratio)
A,E / S = kD (A,R / B)
A,R = A, F - A,E
LLE
A solution of solute (A) in diluent (B) is mixed with solvent (S). The component (B) is slightly soluble in (S). The resulting extract will be
rich in S
poor in B
rich in A
Distillation
- Partial Presure (Eqbm Pressure)
- Dalton Law of Partial Pressure
- Pi = Pi°·xi
- Pᴛ = ΣPi = ΣPi°·xi
—-> Pi = Pᴛ·yi
∴ yi = Pi°·xi / Pᴛ
Pi° = Vapor Pressure
Pᴛ = Total Pressure
yi = equilibrium vapor
xi = equilibrium liquid
Distillation
It is the start of boiling.
Bubble Point
It is the start of condensation
Dew Point
It is the liquid below Boiling Point.
Subcooled Liquid
It is a pure vapor.
Superheated Vapor
Distillation
BOILING POINT DIAGRAM
. ⢸⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀
⢸⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀
⢸⢯⡑⠒⠦⢤ Superheated⠀⠀⠀⠀
⢸⠀⠙⢦⡀⠀⠀⠉⠲⢤⠀⠀⠀⠀⠀⠀
T ⢸⠀⠀⠀⠙⠢⡀⠀⠀⠀⠈⠓⢤<– DP
⢸⠀BP⠀–>⠑⠦⣄⡀⠀⠀⠈⠳⣄⠀
⢸⠀⠀⠀⠀⠀⠀⠀⠀⠀⠉⠒⠤⣀⡀⠈⠳⡄
⢸⠀Subcooled⠀⠀⠀⠀⠀⠉⠙⠒⠾
⢸⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀
⠘⠒⠒⠒⠒⠒⠒⠒⠒⠒⠒⠒⠒⠒⠒⠒⠒⠒⠒⠒
x or y
BP = bubble point
DP = dew point
It is used for extraction of minerals (Gold and uranium ore)
Pachuka Tank
CH 18
Radioactive nuclear waste is treated in
Pulsed Column Extractor
In a counter-currrent extractor, as the axial mixing increases, the extraction efficiency
decreases
P18-59; Agitator - Speed is low
Used for the extraction of oil from oil seed
Bollman extractor
Commonly used leaching solvent in the vegetable industry
Hexane
Antibiotic are best handled in a
Podbielnak Extractor
P15-83
In counter current liquid extractor
One of the liquids maybe pumped at any desired rate
P15-26/48
Raoult’s law is only applicable only if ideal solution, wherein the total volume of the mixture is the sum of individual volume.
An example of solution that will follow Raoult’s law most closely is
A solution of benzene, toluene, and oxylene
They have benzene ring or same structure
Distillation
Relative Volatility
It is used to determine the ease of difficulty of separating components by distillation
αAB = PA°/PB°
yA (1-xA) αAB = -------------
xA (1-yA)
E13-20 (1=A; 2=B)
A = MVC; ↓BP ↑P
B = LVC ; ↑BP
xB = 1-xA
yB = 1-yA
αAB shouldn’t be close to 1
5 Classifications of Distillation
- Bacth Distillation
- Flash Distilation
- Steam Distillation
- Simple Continuous Distillation
- Continuous Distillation with Reflux (Rectification)
Batch Distillation
Rayleigh Equation
`
A1 B1
ln —- = αAB · ln ——
A2 B2
D DA
↑ DB
| |
F → | |
A1 | |
B1 ↓
B A2
B2
E13-127
B = residual Liquid
Flash Distillation
Fraction of the feed vaporised
Formula for ƒ
` - (1-ƒ) x xF
y = ———- + ——-
ƒ ƒ
V y
↑
| |
F → | |
xF | |
↓
L x
Compute x=xA using Relative volatility
ƒ = V/F (amount of feed vaporised
Flash Distillation
Temperature of Liquid and Vapor when separated using the Txy diagram
` - (1-ƒ) x
M = ———-
ƒ
Steam Distillation
Pounds of theoretical steam
’ nS Pᴛ - PB°
——- = ————
nB PB°
n = m/MW
PB° = HB
Simple Continuous Distillation
Relative Volatility
’ DA BB
αAB = —— ·——-
DB BA
D DA
↑ DB
| |
F → | |
A | |
B ↓
B BA
BB
