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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.


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)


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



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=0.0153: 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=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.



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



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)



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


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), 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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