EDL Anlagenbau Gesellschaft mbH
Moscow, 28-30 March 2012
EDL Anlagenbau Gesellschaft mbH
Process Simulation of Solvent Deasphalting Plants
with PRO/II based on Thermodynamic Equilibrium Data
"VLE K -Values - Fill Options"
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Introduction
SDA, the Solvent Deasphalting technology is actually one of the
most interesting „Bottom to Barrel“ technology for heavy residues
in modern refineries
? • Large price differences between light sweet crudes and heavy sour crudes
created strong incentives for bottom processing tecchnologies
• Old fashion technology SDA in the lube oil refinery
will be more and more also applied in fuel oil refineries, too
• The SDA technology is the lowest investment cost variant compared to
Gasification, Visbreaker, Hydrocracker, Coker et al
• In the best case both products DAO as well as Pitch can be converted in
further process steps to valuble products, no further residues will be available
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Integration of SDA in modern Refinery
VDU AR
Crude
SDA
ADU
VR
Bitumen plant
Asphalt (Pitch)
Bright Stock
FCC -Plant
Hydrocracker
Lube Oil Refinery
Fuel Oil Refinery
DAO
ADU…Atmospheric Distillation Unit
VDU…Vacuum Distillation Unit
SDA…Solvent Deasphalting
AR…..Atmospheric Residue
VR…..Vacuum Residue
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Typical SDA
a typical SDA plant is a PDA, e.g.
- Propane Deasphalting Plant -
The plant normally consists of the following parts:
• Propane Extraction
• DAO Train
• Asphalt Train
• Propane Condensation and Recovery
• Pressure Relieve -, Slop - and Flushing system
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SDA simulation and design
The simulation and design of a SDA , especially the
liquid –liqud extraction process is a challenging task !
? • the feed, Vacuum Residue can only be simulated with pseudo
components e.g. it is impossible to use components from the data base
with a defined structure
• the pseudo components have no structure to produce BIPs from the
UNIFAC –Model to build activity coefficients between the components
• the liquid –liquid extraction process for the SDA is based on the different
solubilities between the solvent and the hydrocarbons
• BIPs are necessary to calculate the equilibria in the two liquid phases,
the DAO and the Asphalt phase
BIP… Binary Interaction Parameters
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Model Basis: „Chueh and Prausnitz“
The BIPs can be calculated based on a publication from Chueh and Prausnitz
(1967) for an EOS (Equation of State) via the partial molar volumes of the
multicomponent liquid mixture:
)(5.0 bT
a
b
RTP
Equation of State:
Partial differentiation of EOS:
with the mixing rules for a mixture and used for
),,,,,,(........,,,, biaiciciciiiijiii TPxfababa
222/12
2/1
)(
2
)(
)(
)/()(2
)1(
b
b
T
a
b
RT
Tb
babax
b
b
b
RT i
kkii
k
k
0)( and 0)(
2
2
cc TT
PP
0867.0 and 4278.0a b
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applying the pseudocritical rules to the critical region: 93,0RT
)()(
)()(
'
'
RCMCTCMCM
RCMCTCMCM
TD
TDTTTT
Further, with adjustments to SRK and PR applied in PRO/II we get
the BIP„s between the components:
n
CMjCMi
CMjCMi
ijk
2/)(1
3/1'3/1'
3/1'3/1'
3n (the best fit with experimental data)
Model Basis: „Chueh and Prausnitz“
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Notation
factor ..acentric..........
EOS KwongRedlich in parameter essdimensionl....,
phase liquidin ffraction ....molex.........
mixture of volumecritical true.........
mixture of volumeicalpseudocrit corrected.......
mixture of volumeicalpseudocrit........
phase liquidin k component of memolar volu partial..........
mixture liquidor liquid of lume..molar vo..........
mixture liquid of volume..totalV.........
re temperatureduced..........T
ure..temperatT.........
pressure ..totalP.........
parametersn interactiofor sBIP'.........k
region critical theofunction t correction)...D(T
EOS KwongRedlich in nstantsb.......coa,
a
CT
'
CM
R
ij
R
b
CM
k
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PRO/II PFD- one stage
Typical one stage liquid –liquid extraction unit:
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Pseudo component feed Vacuum Residue (VR)
kg/kg 9669.015 d
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Pseudo component properties
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PRO/II- K-value –Fill Options
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EOS for „Fill –Options“
The following EOS are awailable for the „Fill –Option“:
- Modified Chueh Prausnitz Hydrocarbon Fill -
• Soave Redlich Kwong
• SRK –Panagiotopoulos-Reid
• SRK –Modified Panagiotopoulos-Reid
• SRK –SIMSCI
• Peng –Robinson
• PR –Panagiotopoulos-Reid
• PR –Modified Panagiotopoulos-Reid
• Predictive Peng Robinson 78
• Tacite
The best fit with practical results we achieved with the
SRK –Modified Panagiotopoulos Reid thermodynamic !
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BIPs calculation
BIPs calculated from the output report:
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Stream list
DAO: 28.5 %, Asphalt : 71.5 %
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VR-DAO-Asphalt TBP
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VR-DAO-Asphalt distribution
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Property list
As shown in the property list special data as S, V, Ni, Fe, N and CCR
can be controlled in the DAO, Asphalt via a distribution in the feed (VR):
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Bench scale tests
The theoretical results were compared to bench scale tests in a autoclave:
Conditions: subcritical pressure from 30 to 35 bar and
temperature about 50°C
Solvent: Propane (100%)
Autoclave
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Bench scale tests
Results: DAO and Asphalt from the bench scale unit
DAO…..Deasphalted oil
AS……..Asphalt (Pitch)
Asphalt DAO
*…SRK -Mod Panag. -Reid
**…PR -Mod Panag. -Reid
The SRK Modified Panagiotopoulos -Reid method gives the best fit to the practical results !
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Study of thermodynamic models
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Solvent impact
The choise of the solvent or solvent mixture is very important !
Asphaltenes
Resins
Oils
Cru
de
Oil
Am
os
ph
eri
c R
es
idu
e
Va
cu
um
Res
idu
e
Pro
pa
ne
Pre
cip
ita
te
Pe
nta
ne P
rec
ipit
ate
Hep
tan
e P
rec
ipit
ate
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Simulation studies of Solvent mixtures
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Ternary plots -Temperature influence-
Ternary plot from literature:
1 2
3
Solvent to Feed ratio
(tie lines):
1…0,5
2…3,0
3…8,0
Binodal curves
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Ternary plot – Pressure influence -
Binodal curves
Solvent to Feed ratio
(tie lines):
1…0,5
2…3,0
3…8,0
1 2
3
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PRO/II simulation of multiple stage extraction
Heater on stage 1 to precipitate Asphalt
Controller for precipitation
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Ternary plot – Pressure influence -
The number of trays are not so important !
For the design the
HTU, NTU concept
must be applied !
HTU…Height of Transfer Unit
NTU…Number of Transfer Unit
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The Solvent Deasphalting (SDA) is a key technology processing heavy
residues to valuable oils (DAO, Deasphalted Oil) and asphalt (Pitch) for the
Bitumen production. The process will be more and more interesting also in
fuel oil refineries as a “Bottom to Barrel” technology with low costs.
The calculation of the extraction process with NPB components is difficult
because of the lack of BIPs between the components. Other ways to build
up the data from the UNIFAC model are not applicable.
The model from CHUEH and PAUSNITZ, published in the AIChE Houston
Meeting in 1967 is applicable to estimate the BIPs between the NBP
components and the solvents, finally to calculate the extraction of the SDA
for high pressure.
Summary
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Summary
The model application in the PRO/II simulation program under the
Equation of State (EOS) with the VLE K values –“Fill Option” is the basis
for the complete process simulation of the whole SDA process.
Experimental results have shown that the model can be applied to design
the SDA process with different solvents (Propane, Butane etc.) and
solvent mixtures for the sub- and supercritical extraction processes.
Further investigation should be done to apply the model also to other
extraction technologies e.g. solvent extraction with furfural or NMP.
Thank you for your attention !
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