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Amine hydrochlorides in refinery overheads:
Solving corrosion problems through electrolyte process simulation
Prodip Kundu
OLI Systems Inc.
2014 Software Global Customer Conference September 30 - October 2, 2014
Refinery overhead corrosion
Contain complex mixtures of hydrocarbons, water, inorganic and organic acids, and various ionic species.
Composition and phase behavior changes rapidly as it is being condensed.
Acids or salts present in the overhead system can cause corrosion when the right conditions exist.
Organic neutralizing amines are commonly used to combat corrosion in refinery crude column overhead systems.
Corrosion due to neutralizing amines in refinery overhead systems and subsequent corrosion-related failures are frequently reported.
In order to avoid expensive material solutions (i.e., Ti), we need to understand the overhead chemistry better.
Refinery overhead corrosion
Acidic chloride-based corrosion:
Residual salts hydrolysis:
Amine hydrochloride salts formation:
RNH2 v + HCl v ↔ RNH3Cl s/l
RNH3Cl s/l + H2O ↔ RNH3+ aq + Cl− (aq)
Refinery overhead corrosion
Failures can be traced to the formation of amine hydrochlorides, either as hygroscopic solids or concentrated solutions.
Lack of understanding of physical properties, thermochemical behavior and phase equilibria of amines and their hydrochloride salts.
Root Cause of Failures:
OLI Systems’ Mixed-Solvent Electrolyte (MSE) model:
Phase equilibria in mixtures containing various amines, ammonia, HCl, CO2, H2S, water and hydrocarbons.
The model predicts the formation of solid salts or concentrated amine hydrochloride solutions that may induce corrosion.
Mixed-solvent electrolyte model (MSE): Thermophysical Framework
Themodynamic framework
Phase and chemical
equilibrium algorithm
Applications (process, corrosion, oilfield scaling, etc.)
Standard-state properties of
solution species
Excess Gibbs energy model
Gas-phase equation of
state
Thermo-chemistry of
species
Adsorption models
Transport properties and
surface tension
Structure of the thermodynamic model
Definition of species that may exist in the liquid, vapor, and solid phases
Excess Gibbs energy model for solution nonideality
Calculation of standard-state properties
Helgeson-Kirkham-Flowers equation for ionic and neutral aqueous species
Standard thermochemistry for solid and gas species
Algorithm for solving phase and chemical equilibria
Standard-state properties: Aqueous species
Helgeson-Kirkham-Flowers-Tanger equation
Temperature and pressure dependence of partial molar volumes and heat capacities based on ion solvation theory
Computation of standard-state Gibbs energy and enthalpy of formation and entropy by thermodynamic integration
Estimation methods for the HKF parameters
Outline of the model: Solution nonideality
RT
G
RT
G
RT
G
RT
G exII
exLC
exLR
ex
LR Debye-Hückel theory for long-range electrostatic interactions
LC Local composition model (UNIQUAC) for neutral molecule interactions
II Ionic interaction term for specific ion-ion and ion- molecule interactions
Excess Gibbs energy
i j
xijji
i
i
exII IBxxn
RT
G
)aI(cb)I(B xijijxij 1exp
ion interaction parameters
Outline of the model: Chemical equilibrium calculations
For a sample chemical reaction:
At equilibrium
with
dDcCbBaA
bB
aA
dD
cC
bB
aA
dD
cC
0
xx
xxln
RT
G
i
0ii
0 vG
Standard-state chemical potential of i
Solubility and vapor-liquid equilibria are governed by analogous equations
Infinite-dilution properties Thermochemical databases for aqueous systems
Helgeson-Kirkham-Flowers model for T and P dependence
MSE-AmineHCL Databank
MSE Databank
Thermodynamic Framework Mixed-solvent electrolyte model (MSE)
Subset of the chemistry of interest (i.e., CO2, H2S, H2O, NH3, HCL, NH4CL, 56 Hydro- carbons and selected mixtures)
AmineHCL Databank
Parameters for amine hydrochlorides
Private databank, available only to consortium members until November 15, 2014
MSE Databank
New MSE databank, available
from November 15, 2014
New MSE Parameters
Pure components 20 amines 20 amine hydrochlorides
Binary systems Amines and water Amines and hydrocarbons Amine hydrochlorides and water
Ternary systems
Amines, water and hydrocarbons Amines, water and hydrogen sulfide Amines, water and carbon dioxide
Quaternary systems
Amines, water, hydrogen sulfide and carbon dioxide
Amines and Amine hydrochlorides
Methylamine CH3NH2 Dimethylamine (CH3)2NH Trimethylamine (CH3)3N Ethylamine CH3CH2NH2 Diethylamine CH3CH2NHCH2CH3
Propylamine CH3(CH2)2NH2 Butylamine CH3(CH2)3NH2 2-Butylamine CH3CH2CH(CH3)NH2 Cyclohexylamine c-(CH2)5CHNH2 Ethylenediamine H2N(CH2)2NH2
Morpholine c-(CH2)2O(CH2)2NH N-Methylmorpholine c-(CH2)2O(CH2)2NCH3
N-Ethylmorpholine c-(CH2)2O(CH2)2NC2H5 Ethanolamine (MEA) HO(CH2)2NH2
Diethanolamine (DEA) HO(CH2)2NH(CH2)2OH Dimethylethanolamine (DMEA) (CH3)2N(CH2)2OH Diglycolamine (DGA) HO(CH2)2O(CH2)2NH2 N-Methoxypropylamine H2N(CH2)3OCH3
Dimethylisopropanolamine HOCH(CH3)CH2N(CH3)2
Methyldiethanolamine (MDEA) CH3N(C2H4OH)2
Thermodynamic properties collected & stored in the databanks
For pure amines and amine hydrochlorides:
Standard-state properties Gibbs energy of formation Enthalpy of formation Absolute entropy
Critical properties Critical temperature Critical pressure Critical volume Densities
Molar volume Van der Waals surface & area parameters
Amines in the gas phase Amines in the liquid phase Solid amine hydrochlorides
Amines
Heat capacities
Gaseous amines Liquid amines Solid amine hydrochlorides
Pure liquid amines
Solid amine hydrochlorides
Liquid amines
Thermodynamic properties used to evaluate MSE parameters
1. Vapor pressure as a function of temperature
2. Speciation data at various temperatures (i.e., dissociation constants, distribution of species, pH data)
3. Vapor-liquid equilibria (VLE) data (i.e., isobars, isotherms, isopleths, relative volatility)
4. Liquid-liquid equilibria (LLE) data
5. Solid-liquid equilibria (SLE) data (i.e., freezing point depression)
6. Sublimation data
7. Caloric properties (i.e., heat capacity, heat of mixing, dissolution, dilution)
8. Densities of aqueous solutions at varying temperatures
Which parameters were regressed for amines?
Standard-state Gibbs energy (fGo)
Absolute entropy (So)
UNIQUAC parameters Interaction between neutral species 4 parameters (linear temp. dependence) 6 parameters (quadratic temp. dependence)
UNIQUAC density parameters For aqueous amines 2/3 parameters out of 6 required
Aqueous amines & Corresponding amine-H+ ions
Amines and water Amines and hydrocarbons
HKF parameters For all aqueous species (neutral or ionic ) Maximum 7 parameters in the model
Amine-H+ ions
Aqueous solution of amines
Which parameters were regressed for amine hydrochlorides?
Standard-state Gibbs energy (fGo)
Absolute entropy (So) 21 amine hydrochlorides (two possible solid
phases for ethylamine hydrochloride)
Solid amine hydrochlorides
Ion interaction parameters 4 parameters for almost all pairs 5 parameters (ethanolamine ion-chloride ion)
6 parameters (hydrogen morpholine ion-chloride)
Between Amine-H+ ions & chloride (Cl-) ions
Subcontractors: Southwest Research Institute (SwRI, San Antonio, TX) Laboratory of Thermophysical Properties (LTP, Oldenburg, Germany)
Hydrolysis reaction constants: AMINE +H2O = AMINE-H+ + OH-
Propylamine
-6.0
-5.5
-5.0
-4.5
-4.0
-3.5
0 25
50
75
100
125
150
175
200
225
250
275
300
t / C
log
Kb
Ref. 1 Ref. 2,6
Ref. 3,6 Ref. 4,6
Ref. 5,6 Ref. 9
Ref. 8 Calc.
sec-Butylamine
-6
-5.5
-5
-4.5
-4
-3.5
-3
0 50 100 150 200 250 300 t / C
log
Kb
Ref. 1
Ref. 2
Calc.
Hydrolysis constants (Kb) for all 20 amines in water (temperature range from 0 to 300oC)
Diglycolamine
10
11
12
13
14
0.0001 0.001 0.01 0.1 1X DGA
pH
25C, ref. 1
Calc.
N-Methylmorpholine
7.5
8.5
9.5
10.5
15 30 45 60 75 90t / C
pH
I=0.01,0.002 m I=0.05, 0.002 mI=0.25, 0.002 m I=0.01, 0.01 mI=0.05, 0.01 m I=0.25, 0.01 mI=0.01, 0.05 m I=0.05, 0.05 mI=0.25, 0.05 m 0.01,0.002-calc.0.01,0.01-calc. 0.01,0.05-calc.0.05,0.002-calc. 0.05,0.01-calc.0.05,0.05-calc. 0.25,0.002-calc.0.25,0.01-calc. 0.25,0.05-calc.0.52 m NMM - ref. 6 0.52 m NMM - calc.
pH: Amine solutions
pH values were measured at SwRI for 10 aqueous amine solutions as a function of temperature.
Vapor-liquid equilibria (VLE): Aqueous amine solutions
0.0001
0.001
0.01
0.1
1
0 0.2 0.4 0.6 0.8 1X MEA
P /
atm
.
25C: Touchara et al.(1982) 35C: Touchara et al.(1982)
90C: Tochigi et al.(1999) 70C: Lenard et al.(1990)
90C: Lenard et al.(1990) 60C: Nath&Bender(1983)
78C: Nath&Bender(1983) 91.7C: Nath&Bender(1983)
25C - calculated 35C - calculated
60C - calculated 70C - calculated
78C - calculated 90C - calculated
91.7C - calculated 0.0000001
0.000001
0.00001
0.0001
0.001
0.01
0.1
1
0 25 50 75 100 125t / C
P M
EA
/ a
tm.
X=0.0317: Kohl&Riesenfeld(1979)
X=0.0687: Kohl&Riesenfeld(1979)
X=0.1122: Kohl&Riesenfeld(1979)
X=0.0153: Texaco(1981)
X=0.0317: Texaco(1981)
X=0.0495: Texaco(1981)
X=0.0687: Texaco(1981)
X=0.1122: Texaco(1981)
X=0.1643: Texaco(1981)
X=0.2278: Texaco(1981)
X=0.0153: Dow(2003)
X=0.0317: Dow(2003)
X=0.0687: Dow(2003)
X=0.1122: Dow(2003)
X=0.1643: Dow(2003)
X=0.3067: Dow(2005)
X=0.5412: Dow(2005)
X=0.7264: Dow(2003)
X=0.8486: Dow(2005)
X=1: Dow(2005)
X=0.0153 - calculated
X=0.0317 - calculated
X=0.0495 - calculated
X=0.0687 - calculated
X=0.1122 - calculated
X=0.1643 - calculated
X=0.2278 - calculated
X=0.3067 - calculated
X=0.5412 - calculated
X=0.7264 - calculated
X=0.8486 - calculated
X=1 - calculated
VLE for all 20 aqueous amine systems over a wide range of temperature, pressure and concentration. Three kinds of VLE (isobars, isotherms and isopleths).
Ethanolamine Ethanolamine
sec-Butylamine
0.001
0.01
0.1
1
10
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1X sec-BuAm
P (
atm
.)
0C - ref. 1 10C - ref. 1 20C - ref. 1 30C - ref. 1 40C - ref. 150C - ref. 1 60C - ref. 1 70C - ref. 1 80C - ref. 1 90C - ref. 10C - calc. 0C - Y 10C - calc. 10C - Y 20C - calc.20C - Y 30C - calc. 30C - Y 40C - calc. 40C - Y50C - calc. 50C - Y 60C - calc. 60C - Y 70C - calc.70C - Y 80C - calc. 80C - Y 90C - calc. 90C - Y
sec-Butylamine
0
0.5
1
1.5
2
35 40 45 50 55 60 65 70 75 80 85t / C
P / a
tm.
X=0.1005X=0.1980
X=0.2985X=0.4982
X=0.6992X=0.8996
X=1X=0.1005-calc.
X=0.1980-calc.X=0.2985-calc.
X=0.4982-calc.X=0.6992-calc.
X=0.8996-calc.X=1-calc.
Vapor-liquid equilibria (VLE): Aqueous amine solutions
VLE for all 20 aqueous amine systems over a wide range of temperature, pressure and concentration. Three kinds of VLE (isobars, isotherms and isopleths).
N-Methylmorpholine
0.0
0.2
0.4
0.6
0.8
0 0.2 0.4 0.6 0.8 1X NMM
P / a
tm.
40C-ref.2
50C-ref.2
60C-ref.2
70C-ref.2
80C-ref.2
90C-ref.2
40C-calc.
50C-calc.
60C-calc.
70C-calc.
80C-calc.
90C-calc.
40C-Y
50C-Y
60C-Y
70C-Y
80C-Y
90C-Y
N-Methylmorpholine
50
75
100
0.0 0.2 0.4 0.6 0.8 1.0
X NMM
t / C
0.25 atm. - ref. 15 0.39 atm. - ref. 150.59 atm. - ref. 15 0.25 atm. - calc.0.39 atm. - calc. 0.59 atm. - calc.0.25 atm. - Y 0.39 atm. - Y0.59 atm. - Y
Vapor-liquid equilibria (VLE): Aqueous amine solutions
VLE for all 20 aqueous amine systems over a wide range of temperature, pressure and concentration. Three kinds of VLE (isobars, isotherms and isopleths).
Caloric properties: Aqueous amine solutions
Diethanolamine
0.55
0.7
0.85
1
0 0.2 0.4 0.6 0.8 1X DEA
Cp
(c
al/g
K)
30C-ref. 1 35C-ref. 1 40C-ref. 145C-ref. 1 50C-ref. 1 55C-ref. 160C-ref. 1 65C-ref. 1 70C-ref. 175C-ref. 1 80C-ref. 1 25C-ref. 220C-ref. 3 30C-ref. 3 40C-ref. 350C-ref. 3 60C-ref. 3 70C-ref. 380C-ref. 3 90C-ref. 3 100C-ref.310C-ref. 4 25C-ref. 4 40C-ref. 455C-ref. 4 10C - calc. 20C - calc.25C - calc. 30C - calc. 40C - calc.50C - calc. 60C - calc. 70C - calc.80C - calc. 90C - calc. 100C-calc.
Heat capacity was measured as a function of temperature and concentration.
Amine – hydrocarbon systems: Liquid-liquid equilibria (LLE)
Diethanolamine + Hexadecane
MSE model is capable of reproducing more complex phase behavior (i.e., VLE, VLLE and LLE) in the whole concentration range.
75
100
125
150
175
200
225
250
275
0 0.2 0.4 0.6 0.8 1X DEA
t /
C
LLE,I, 1 atm: Abedinzadegan&M eisen(1998)
LLE,II, 1 atm: Abedinzadegan&M eisen(1998)
VLE, 0.07 atm: Abedinzadegan&M eisen(1998)
VLE, azeotrope: Abedinzadegan&Abdi(1998)
LLE, 1 atm - calculated
LLE, 0.07 atm - calculated
VLE, 1 atm - calculated
VLLE, 1 atm
VLE, 0.07 atm - calculated
VLLE, 0.07 atm.
Amine – CO2 – H2O systems: VLE for Ethanolamine (MEA) + CO2 + H2O
MSE model is capable of reproducing the behavior of the amine-CO2-H2O ternary system essentially within the scattering of experimental data.
2.5 N, 15.2 wt%, 2.9 m
0.00001
0.0001
0.001
0.01
0.1
1
10
100
0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4
CO2 / MEA (mol/mol)
PC
O2 (
atm
)
25C: M uhlbauer&M onaghan(1957)
100C: M uhlbauer&M onaghan(1957) 40C: Jones et al.(1959)
60C: Jones et al.(1959)
80C: Jones et al.(1959)100C:Jones et al.(1959)
120C: Jones et al.(1959)
140C: Jones et al.(1959)
40C: Lee et al.(1974)100C: Lee et al.(1974)
25C: Lee et al.(1976)
40C: Lee et al.(1976) 60C: Lee et al.(1976)
80C: Lee et al.(1976)
100C: Lee et al.(1976)120C: Lee et al.(1976)
40C: Lee et al.(1976A)
100C: Lee et al.(1976A) 40C: Lawson&Garst(1976)
60C: Lawson&Garst(1976)
80C: Lawson&Garst(1976)
100C: Lawson&Garst(1976)120C-Lawson&Garst(1976)
134.4C: Lawson&Garst(1976)
140C: Lawson&Garst(1976) 80C: Isaacks et al.(1980)
100C: Isaacks et al.(1980)
25C: Bhairi(1984) 60C: Bhairi(1984)
80C: Bhairi(1984)
40C: Austgen et al.(1991) 80C: Austgen et al.(1991)
40C: Shen&Li(1992)
40C: Song et al.(1996)
40C: Park et al.(1997) 60C: Dang&Rochelle(2001)
30C: Singh et al.(2009)
100C: Goldman&Leibush(1959)120C: Goldman&Leibush(1959)
140C: Goldman&Leibush(1959)
60C: Nasir&M ather(1977) 80C: Nasir&M ather(1977)
100C: Nasir&M ather(1977)
40C: Lee et al.(1976) - smoothed100C: Lee et al.(1976) - smoothed
25C - calculated
30C - calculated
40C - calculated 60C - calculated
80C - calculated
100C - calculated120C - calculated
140C - calculated
Amine – H2S –H2O systems: VLE for Ethanolamine (MEA) + H2S + H2O
MSE model reproduces the behavior of the amine-H2S-H2O ternary system consistently well. Total pressures can be reproduced more accurately than partial.
5 N, 7 m, 30 wt%
0.000001
0.00001
0.0001
0.001
0.01
0.1
1
10
100
0 0.2 0.4 0.6 0.8 1 1.2 1.4H2S / MEA (mol/mol)
PH
2S (
atm
)
26.7C: Atw ood et al.(1957) 48.9C: Atw ood et al.(1957) 26.7C: Law son&Garst(1976) 37.8C: Law son&Garst(1976) 93.3C: Law son&Garst(1976) 40C: Lee et al.(1974)100C: Lee et al.(1974) 100C: Nasir&Mather(1977) 40C: Li&Shen(1993) 60C: Li&Shen(1993) 80C: Li&Shen(1993) 100C-Li&Shen(1993) 25C: Lee et al.(1976) 40C: Lee et al.(1976) 60C: Lee et al.(1976) 80C: Lee et al.(1976)100C-Lee et al.(1976) 120C-Lee et al.(1976) 25C - calculated 26.7C - calculated 37.8C - calculated 40C - calculated 48.9C - calculated 60C - calculated 80C - calculated 93.3C - calculated100C - calculated 120C - calculated
Amine – H2S – CO2 – H2O systems: VLE for Diethanolamine (DEA) + H2S + CO2 + H2O
MSE model reproduces partial pressures of CO2 and H2S for amine-H2S-CO2-H2O quaternary system within their experimental uncertainty.
H2S partial pressures
0.00001
0.0001
0.001
0.01
0.1
1
10
100
0.00001 0.0001 0.001 0.01 0.1 1 10 100
Pexp (atm)
Pcalc
(a
tm)
40C: Jane&Li(1997), 30 w% 80C: Jane& Li(1997), 30 wt%
40C: Lal et al.(1985), 2 N 100C: Lal et al.(1985), 2 N
37.8C: Lawson&Garst(1985), 25 wt% 51.7C: Lawson&Garst(1985), 25 wt%
65.6C: Lawson&Garst(1985), 25 wt% 79.4C: Lawson&Garst(1985), 25 wt%
93.3C: Lawson&Garst(1985), 25 wt% 107.2C: Lawson&Garst(1985), 25 wt%
121.1C: Lawson&Garst(1985), 25 wt% 37.8C: Lawson&Garst(1985), 50 wt%
65.6C: Lawson&Garst(1985), 50 wt% 93.3C: Lawson&Garst(1985), 50 wt% 66C: le Bouhelec-Tribouloois et al.(2008), 25 wt% 25C: Lee et al.(1973), 2 N
50C: Lee et al.(1973), 2 N 75C: Lee et al.(1973), 2 N
100C: Lee et al.(1973), 2 N 120C: Lee et al.(1973), 2N
25C: Lee et al.(1973), 3.5 N 50C: Lee et al.(1973), 3.5N
75C: Lee et al.(1973), 3.5 N 100C: Lee et al.(1973), 3.5N
120C: Lee et al.(1973), 3.5 N 50C: Lee et al.(1974), 2 N
25C: Leibush&Shneerson(1950), 2 N 49.7C: Rogers et al.(1997), 2 N
Sublimation data: Pure amine hydrochlorides
1.E-10
1.E-09
1.E-08
1.E-07
1.E-06
1.E-05
1.E-04
1.E-03
1.E-02
1.E-01
1.E+00
0 50 100 150 200 250 300t[C]
p[a
tm]
MSE liquid
MSE solid
Aston&Ziemer 1946
Kisza 1967
1.E-10
1.E-09
1.E-08
1.E-07
1.E-06
1.E-05
1.E-04
1.E-03
1.E-02
0 50 100 150 200 250 300t[C]
p[a
tm]
MSE liquid
MSE solid
Bannard&Casselman 1965
Fearnside 1998
Lehrer&Edmondson 1993
Lehrer&Edmondson 1993, rescaled
Vapor-solid transitions of pure amine hydrochlorides as a function of temperature. SLE and VLE data for amine hydrochlorides-water systems are available.
Methylamine hydrochloride Morpholine hydrochloride
Adding OLI databank to PRO/II
OLI chemistry model wizard creates chemistry model (*.mod) file and it's associated property database (*.dbs) file for use with an OLI calculation engine.
PRO/II Thermodynamic data
Selecting Electrolyte category from PRO/II property calculation system and adding the databank (*.dbs) file to include the chemistry.
PRO/II Flowsheet
PRO/II flowsheet is ready with the new chemistry model.
Applications
OLI worked on specific applications covered by NDAs.
Continual improvements of algorithm convergence.
Studies based on the OLI technology.
A. Patel et al.: Use of ionic modeling to gain new insights on crude unit overhead corrosion, Corrosion 2012.
Upcoming presentations by Shell, Phillips 66, and Athlon at the OLI Simulation Conference, 2014.
OLI is forming special interest group to guide further development of refinery overhead simulation technology.
Summary
Corrosion due to neutralizing amines in refinery overhead systems causes corrosion-related failures and drives up the expenses substantially.
Understanding of physical properties, thermochemical behavior and phase equilibria of amines and their hydrochloride salts is crucial.
MSE model with amine hydrochloride chemistry ensures Getting the chemistry right before flowsheeting.
OLI Systems’ model reproduces phase equilibria in mixtures containing various amines, ammonia, HCl, CO2, H2S, water and hydrocarbons
The model predicts the formation of solid salts or concentrated amine hydrochloride solutions that may induce corrosion
Acknowledgements
Andre Anderko
Pat McKenzie
Margaret Lencka
Peiming Wang
Consortium Members
Southwest Research Institute (SwRI)
Laboratory of Thermophysical Properties (LTP)
Thank You
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