INNOVATIVE EXTRACTION
PROCESSES FOR CHALLENGING FEED-STOCKS
Indian Institute of Petroleum
(Council of Scientific & Industrial Research )
Dehradun
SYMPOSIUM
ON
SOLVENT EXTRACTION REVISITED
FEBRUARY 5TH – 6th , 2010
IIChE (NRC) Auditorium
NEW DELHI-INDIA
Aromatic Extraction
Extraction Step
Removal of Aromatics
Recovery of Aromatics
Capacity
Selectivity
FGH/SK/ATF/LOBS
Production
Pure BTX Production
Solvent Recovery Step : Distillation
Limitations of conventional scheme
 Overlapping of boiling point of feed-stock
& solvent
 High level of impurities in feed stock
Innovations
Required
Examples
De-aromatization of Middle distillate by
using re-extraction
Pure BTX from Straight Run Naphtha
Middle Distillate De-aromatization
 Trend towards increasing use of hydroprocessing
 Not attractive for small refineries as requires high
capital & operating expense
 Loss of valuable aromatics
 Search for alternative to hydrotreatment
 Solvent
extraction
already
established
naphtha fraction and Lube fraction
 Extended to Middle Distillates
for
Kerosene De-aromatization using
Sulfolane Based Extraction

Sulfolane Technology developed jointly with
EIL and HPCL

Demo was given to IOCL on ATF pilot plant at
HPCL, mumbai

Process Package along with EIL was
submitted to IOC Digboi
Limitations of Sulpholane
Based Extraction Technology

Utilities required were high due to
distillation step for the solvent recovery

Further work was initiated at IIP to improve the
solvent recovery process
RE-EXTRACTION
A novel approach for solvent recovery
use
of
Re-extraction Technology

Replacement of energy intensive distillation step
by using reverse extraction

High capacity solvent like NMP can be used in spite
of boiling point overlap with feedstock – No
distillation
Re-Extraction
Solvent
Low Boiling Hydrocarbon Stream– Low energy
required for separation from aromatics
Capacity And Selectivity Of
Solvents For NMP Water Blend
100
80
Thiodipr opionitr ile
Ethyle ne
Glycol
Oxidipr opionitr ile
Sulfola ne
Ethyle ne
C arbonate
60
N itr ome tha ne
D ie thylene
Glycol
40
D im ethy l Sulfox ide
Me thy lfor ma mide
Triethy le ne Gly col
Pr opy le ne Ca rbona te
Tetr ae thy lene Glycol
20
Water
NMP + Water
Ethyle ne
D ia mine
Furfura l
Me thy lca rbam ate
D ie thylene Glyc ol Methy le ther
Selectivity Ù
10
Triethy le ne Tetr am ine
Pr opy le ne
Glycol
N -Methylpyr rolidone
D ipropyle ne Gly col
NMP
0 ..1
0 .2
0 .4
Capacit y Ù
0 .6
0 .8
1 .0
2 .0
Like Dissolves Like
Aromatics in Feed
LPS + Aromatics
Saturate in feed
Extraction solvent
Extract
Phase
Re-extractor
Re-Extraction Solvent
LPS
Lean Solvent
FLOW SHEET WITH RE-EXTRACTION
AROMATIC
EXTRACT
TOP PHASE
LEAN
SOLVENT
WATER
FEED
WATER + NMP
EXT
PHASE
SEC-SOLVENT
FURNACE
FUEL
DEAROM. RAFFINATE
WATER
RE-EXT COL
BOTTOM
WATER
LEAN
SOLVENT
RAFFINATE
PHASE
WATER + NMP
De-aromatization of Heavy Naphtha,
Kerosene and Gas Oil
KTU REVAMP at IOC GUWAHATI
Feed-stocks for De-aromatization
Characteristics
Heavy
Kero.
Gas Oil
Naphtha Fraction Fraction
Density, kg/m3 at 20°C
‘S’ Content, ppm
Viscosity, cst at 40°C
710
44.8
0.76
860
648
2.039
884
1900
5.06
IBP, °C
50%, °C
122
147.5
190
238
213
300
298
396
57.8
42.2
60.7
39.3
FBP, °C
194
Saturates, Wt.%
Aromatics, Wt.%
194.0
69.8
30.2
VALUE ADDITION
Feedstocks
Raffinate
Extract
Heavy Naphtha Solvent,
Diesel blending
component
Kerosene
Gas Oil
MS pool
blending
Component
(BNZ free)
Superior kerosene Solvent for
pesticides
High Cetane Diesel Solvent for
pesticides
Challenges with Given feed-stocks
Three
different feed-stocks of different boiling range
• Conventional scheme with single solvent not feasible –
Boiling point overlap
Re-extraction with NMP using blocked out mode
operation is an alternative
De-aromatization in
block out mode
Solvent
Heavy
Naphtha
De-aromatized
Heavy Naphtha
Kero
Gas
Oil
EXTRACTION
UNIT
De-aromatized
Kero-fractiom
De-aromatized
Gas Oil
Experimental studies

Detailed experimental studies have been carried
out with feedstock provided by Guwahati Refinery
 Feed stocks analysis
 Single stage LLE data

- Extraction

- Re-extraction
 Continuous column studies for extraction and
re-extraction steps

Total number of data point generated = 175
Typical Experimental Results
Characteristics
Raffinate
Aromatic Content, wt.%
Smoke Point, mm
Cetane Index
Yield, wt%
Extract
Aromatic Content, wt.%
RON
Density
Sulphur, ppm
Naphtha
Kerosene
Gas Oil
7.75
21.6
21
16.1
60.8
71.2
56
82.4
73.48
96
0.8369
18 (from 44)
83.3
91.3
0.9423
250 (from 648)
600
Raffinate and extract produced met
the desired specifications
(from 1900)
Simulation And Modeling

Feed Characterization (Model Hydrocarbons)
GC & GC MS Hydrocarbon type analysis

Prediction of LLE Based on UNIFAC

Development and Simulation of Process Flow sheet
Using ASPEN PLUS

Optimization of Heat Integration and Operating
Parameters to Minimize Utility Requirements
Model Hydrocarbons Representing Gas Oil
Hydrocarbon
Type
Rep. Model
Hydrocarbons
Paraffins
n-Hexadecane
Non Condensed
Cycloparaffins
Structural
Formula
Mol.
Formula
CH3(CH2)4CH3
n-Pentadecyl
Cyclopentane
B.P.
oC
C16H34
287
C20H40
351
C12H22
239
C14H22
264
C16H14
306
C13H14
274
C15H30
C2H5
Condensed
Cycloparaffins
Bicyclohexyl
C8H17
Alkyl Benzenes
n-Octyl Benzene
Indanes &
Tetralins
1-n-Hexyl 1,2,3,4
Tetrahydro
Naphthalene
C6H13
C3H7
Diaromatics
1-n-Propyl
Naphthalene
C2H5
Bi-phenyls
1,1-Diphenylethane
C14H14
274
Fluorenes
Fluorene
C13H10
297
Experimental And Simulated Aromatics
Concentration On Solvent Free Basis
20
SIMULATED AROMATICS CONC., Wt%
SIMULATED AROMATICS CONC., Wt%
110
18
100
16
+10%
90
+10%
14
12
80
-10%
10
70
-10%
60
50
Simulated
Exptl
8
6
4
Simulated
2
Exptl
0
40
40
50
60
70
80
90
EXPERIMENTAL AROMATICS CONC., Wt%
a) EXTRACT
100
0
5
10
15
EXPERIMENTAL
AROMATICS CONC., Wt%
Fig
b) RAFFINATE
20
Summary: De-aromatization
of Middle Distillate

Re-extraction Technology is available for dearomatization of petroleum fractions of
different boiling ranges

Process package for similar application is
already completed
Pure BTX from
Straight Run Naphtha
Background

Huntsman Petrochemicals Ltd., approached IIP for
revamp of their NMP unit

Revamp involved changing the feed from Reformate
to Straight Run Naphtha to produce pure BTX and
de-aromatized Naphtha as cracker feed
• To increase feed-product differential costs
• To increase the Naphtha cracker capacity
performance
and
Improvement in Naphtha Cracker
Performance
 Conventional Naphtha Cracking
C2/C3 Olefins
Paraffinic Naphtha
~10% aromatics
CRACKER
 Dearomatized Naphtha Cracking
C2/C3 Olefins
Paraffinic Naphtha
~10% aromatics

ARU
Pure B T & X
~10% capacity addition can be obtained in the Cracker
 Off spec cracker naphtha feeds can be used
 Improvement in economic due to production of pure BTX
Possible Feed-stocks for
BTX production
Conventional
Challenging
Characteristics
Reformate
PG
SR
Naphtha
Total Paraffins, wt.%
24.4
7.38
65.42
Total Naphthenes, wt.%
2.42
8.78
25.14
Total Aromatics , wt.%
73.18
83.84
9.44
AR/ Naphthenes Ratio
30.2
9.5
0.37
Challenges to produce pure BTX
from SR Naphtha

Technologies for production of pure BTX from high
aromatics feed stocks already established
Conventional
feed
stocks
aromatics and low in naphthenes

are
rich
Proposed feed stock : Naphtha
 Aromatics content low (~10 wt.%)
 Ratio of aromatic to naphthenes less than 1
(Higher Naphthenes)
Difficult to produce pure aromatics
without innovations
in
SIMPLIFIED PROCESS FLOW SHEET FOR THE
PRODUCTION OF PURE AROMATICS
EXTRACTOR
FEED
STRIPPER
SOLVENT
RECOVERY
RAFFINAT
E WASH
RAFFINATE
EXTRACT
BENZENE
SOLVENT
REGENERATOR
Effect of carbon number and HC type
on separation with solvent
Relative solubility
Relative volatility
Separation of naphthlenes is comparatively difficult by distillation
Stripper is limiting
Innovations for Removal of
Naphthenes
Temp.
Gradient
Extra
backwash
Extract
Purity
Backwash
Antisolvent
Extract Purity Improvement
For achieving targeted purities of aromatics various
combinations of the operating variables were tried:

Different S/F in the extractor

Use of different backwash streams along with existing
backwash stream

Use of water as antisolvent

Use of secondary solvent
Continuous column extraction runs with
straight run naphtha at 40 °C
• Feed : S R Naphtha with 10% aromatics
• Solvent : NMP with water
Run type
• Back wash : Benzene Rich C6 cut
• S/F : 3.0 w/w
Extractor Bottom
Aromatic wt%
% aromatic Purity in
stripper runs
Only Feed & Solvent
47.09
With Back wash
63.94
C6A=98.75
C7A=96.24
C8A=93.23
With H2O & Back
wash & Recycle
78.28
C6A=99.17
C7A=98.96
C8A=95.73
With H2O, recycle
Back wash &
Pentane
81.32
C6A=99.93
C7A=99.37
C8A=98.50
Processing of Straight Run Naphtha
Composition, wt.%
Raffinate
P-63.4
Naphtha N-25.7
A-10.9
BW + recycle
Pentane
EXTRACTOR
Water
P-65.83
N-31.60
A-2.57
Solvent
P-16.5
Extract N-2.2
A-81.3
Simulation And Modeling Of BTX Unit

Required
modified
interaction
parameters
for
naphthenes and solvent

Large Number of LLE data with naphthenes ( Model
HC) and solvent were generated which were not
required for conventional system,
for simulation
studies

Simulation of Process Flow sheet Using ASPEN
PLUS
Plant simulation Diagram
Closed loops Simulation: Results gives us the confidence that
data are correct and well fitted for real plant operation
BTX Quality Achieved

Solvent contamination

Non-aromatic content
• bp<110 °C
• 110 °C<bp<136 °C
• 136 °C<bp<138 °C
•
• 145 °C<bp
: 1ppm
(based on normal boiling point)
: 700 ppm wt/wt
in benzene fraction
: 2000 ppm wt/wt
in toluene fraction
: 3000 ppm wt/wt
in ethyl benzene fraction
: 5000 ppm wt/wt
in remaining fraction
Process Economics
 The concept & economics of integrating Cracker
with Straight Run Naphtha dearomatization was
published in April 2007 issue of Hydrocarbon
processing much after our work
 The author studied two types of off spec. Naphtha
for integrating dearomatization and cracking on a
cracker
 The payout period was found to be ~0.8 year
IIP Technology for pure BTX
from S R Naphtha
Outcome
 Technology successfully developed and
demonstrated on lab scale
 Plan for retrofitting the above in the existing
unit was also provided to the client in UK
THANK YOU
www.csir.res.in
www.iip.res.in