BATCH & STEAM BATCH & STEAM DISTILLATIONDISTILLATION

DIFFERENTIAL DISTILLATIONDIFFERENTIAL DISTILLATION

BATCH DISTILLATION BATCH DISTILLATION DIFFERENTIAL DIFFERENTIAL

BECAUSE BECAUSE EQUILIBRIUM EQUILIBRIUM CHANGES AS THE CHANGES AS THE PROCESS PROCEEDSPROCESS PROCEEDS

BASIC COMPONENTS BASIC COMPONENTS IN THE SYSTEMIN THE SYSTEM STILLSTILL CONDENSERCONDENSER DISTILLATE RECEIVERDISTILLATE RECEIVER

DISTILLATE RECEIVER

STILL

QR

CONDENSER

QC

BATCH DISTILLATION MODEL BATCH DISTILLATION MODEL

MODEL FOR THIS PROCESS IS THE RAYLEIGH EQUATION INSTANTANEOUS MODEL:

INTEGRATING OVER FINITE SEPARATION:

xy

dx

L

dL

ydLxdLLdxxLddLA

)113.11()(

)103.11(ln

212211

2

11

2

1

2

avg

x

x

L

L

LLxLxL

xy

dx

L

L

L

dL

SOLUTION TO MODELSOLUTION TO MODEL

EVALUATION OF THIS INTEGRAL REQUIRES EQUILIBRIUM DATA, y = y(x) IF DATA IS EMPIRICAL OR GRAPHICAL,

THEN GRAPHICAL INTEGRATION IS USED IF THERE IS A CORRELATION FUNCTION

FOR VLE, THEN ANALYTICAL INTEGRATION IS POSSIBLE

SIMPLIFIED SOLUTIONSSIMPLIFIED SOLUTIONS

USING MODIFIED RAOULT’S LAWUSING MODIFIED RAOULT’S LAW

THIS APPROACH CAN BE USED TO DESIGN THIS APPROACH CAN BE USED TO DESIGN THE CONTROL SYSTEM FOR THE BATCH THE CONTROL SYSTEM FOR THE BATCH DISTILLATIONDISTILLATION

Farschman, C. A.; Diwekar, U., Farschman, C. A.; Diwekar, U., Dual Composition Control in a Novel Dual Composition Control in a Novel Batch Distillation ColumnBatch Distillation Column , , Ind. Eng. Chem. ResInd. Eng. Chem. Res.; (Article); 1998; .; (Article); 1998; 37(1); 89-96.37(1); 89-96.

x

x

x

x

sys

sys Kx

dx

PP

x

dx

L

LKx

P

Pxy

001

1*

ln*

0

SIMPLIFIED SOLUTIONSSIMPLIFIED SOLUTIONS SYSTEM WITH CONSTANT RELATIVE SYSTEM WITH CONSTANT RELATIVE

VOLATILITY:VOLATILITY:

AB

A

A

B

B

B

BAB

A

A

B

BAB

A

A

B

AAB

B

A

B

A

BBAA

B

A

B

A

B

AAB

B

A

n

n

n

n

n

n

n

n

n

dn

n

dnRESOLVING

n

n

dn

dn

dndn

dndn

dnydndnydnVAPORIZEDdnFOR

n

n

x

x

x

x

y

y

1

0000

lnln

:

&:

BATCH DISTILLATION WITH BATCH DISTILLATION WITH RECTIFICATIONRECTIFICATION

USED TO IMPROVE SEPARATIONUSED TO IMPROVE SEPARATION CONSTANT REFLUXCONSTANT REFLUX CONSTANT OVERHEAD COMPOSITIONCONSTANT OVERHEAD COMPOSITION

Ivonne, R. D.; Vincent, G.; Xavier, J., Heterogeneous Entrainer Selection for the Separation of Azeotropic and Close Boiling Temperature Mixtures by Heterogeneous Batch Distillation, Ind. Eng. Chem. Res.; (Article); 2001; 40(22); 4935-4950

BATCH DISTILLATION WITH BATCH DISTILLATION WITH RECTIFICATIONRECTIFICATION

HIGHER PRODUCT CONCENTRATIONHIGHER PRODUCT CONCENTRATION INCLUDE MASS BALANCE FOR REFLUX FROM INCLUDE MASS BALANCE FOR REFLUX FROM

CONDENSER BACK INTO THE RECTIFICATION CONDENSER BACK INTO THE RECTIFICATION COLUMNCOLUMN

OPERATING LINE EQUATION:OPERATING LINE EQUATION:

D

LR

R

xx

R

R

V

Dxx

V

Ly nD

nn

Dn

n

nn

11111

BATCH DISTILLATION WITH BATCH DISTILLATION WITH RECTIFICATIONRECTIFICATION

GRAPHICAL REPRESENTATION GRAPHICAL REPRESENTATION CONSTANT REFLUXCONSTANT REFLUX CONSTANT COMPOSITIONCONSTANT COMPOSITION

PERRY’S, SECTION 13

DESIGN FOR BATCH WITH DESIGN FOR BATCH WITH RECTIFICATIONRECTIFICATION

ADDING REFLUX TO BATCH DISTILLATION SYSTEM THAT IS EQUIVALENT TO A

CONTINUOUS DISTILLATION FEED BELOW THE BOTTOM TRAY CONSTANT CHANGE OF OPERATING LINE

CAN BE ANALYZED USING CONTINUOUS MODEL A SERIES OF COLUMNS ARE CONSTRUCTED BOTTOMS FROM ONE COLUMN BECOMES THE

FEED TO THE NEXT COLUMN EACH COLUMN REPRESENTS A SHORT

INTERVAL OF TIME IN THE DISTILLATION

BATCH DISTILLATION MODELBATCH DISTILLATION MODEL USES CONTINUOUS DISTILLATION MODELSUSES CONTINUOUS DISTILLATION MODELS

2

3

4

5

6

7

8

9

1

10

25_PERCENT

2

3

4

5

6

7

8

9

1

10

50_PERCENT

2

3

4

5

6

7

8

9

1

10

75_PERCENT

2

3

4

5

6

7

8

9

1

10

100_PERCENT

M1

INITIAL_CONC

25_LIQ 50_LIQ 75_LIQ FINAL_STILL

25_VAP

50_VAP

75_VAP

100_VAP

FINAL_DISTIL

STEAM DISTILLATION

DIRECT INJECTION USED WHEN WATER CAN BE MIXED WITH THE SYSTEM REPLACES THE REBOILER WITH DIRECT STEAM INJECTION

MAY HAVE A FEED AT THE TOP TRAY AND THEN PROCESS BECOMES STEAM STRIPPING

http://www.p2pays.org/ref/01/images/0003421.gif

STEAM DISTILLATION DESIGNSTEAM DISTILLATION DESIGN WHEN WATER IS INSOLUBLE IN THE

OTHER LIQUID VAPOR PRESSURE OF EACH

COMPONENT IS NOT INFLUENCED BY THE PRESENCE OF THE OTHER

FIND Tsys BY TRIAL & ERROR

sys

BB

sys

AA

sysBA

P

Py

P

Py

PPP

**

**

STEAM DISTILLATION EXAMPLESTEAM DISTILLATION EXAMPLE

RECOVERY OF CHAMOMILERECOVERY OF CHAMOMILE

http://www.chamomile.co.uk/distframe.htm

CONDENSED STEAM AND OIL ARE INSOLUBLE.

OIL IS RECOVERED USING DECANTATION, LIQUID-LIQUID SEPARATOR.

STEAM STRIPPERSSTEAM STRIPPERS

TYPICAL CONFIGURATION WITH TYPICAL CONFIGURATION WITH RECTIFICATIONRECTIFICATION

Yng Long Hwang, George E. Keller, and James D. Olson, Steam stripping for removal of organic pollutants from water. 1. Stripping effectiveness and stripper design, Ind. Eng. Chem. Res.; 1992; 31(7) pp 1753 - 1759;

STEAM STRIPPINGSTEAM STRIPPING AS APPLIED TO CRUDE COLUMNS IN OIL AS APPLIED TO CRUDE COLUMNS IN OIL

REFINERIESREFINERIES

Ji, S.; Bagajewicz, M., On the Energy Efficiency of Stripping-Type Crude Distillation , Ind. Eng. Chem. Res.; (Article); 2002; 41(23); 5819-5825

STEAM CONSUMPTIONSTEAM CONSUMPTION STEAM RATE IN TERMS OF PARTIAL

PRESSURES

MINIMUM STEAM CONSUMPTION, IN TERMS OF RELATIVE VOLATILITY

*

)(

B

BBB

B

sys

BB

steam

B

steam

BB

steamBsys

BB

steamsteam

B

steam

P

P

P

P

MW

MW

m

m

MWP

MWPP

MWP

MWP

m

m

B

steamBsteam

BB

steamsteam

B

steam

MW

MW

MWP

MWP

m

m,*

*