Amine hydrochlorides in refinery overheads: Solving corrosion problems through electrolyte process simulation Prodip Kundu

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1 Amine hydrochlorides in refinery overheads: Solving corrosion problems through electrolyte process simulation Prodip Kundu OLI Systems Inc Software Global Customer Conference September 30 - October 2, 2014

2 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.

3 Refinery overhead corrosion Acidic chloride-based corrosion: Residual salts hydrolysis: Amine hydrochloride salts formation: RNH 2 v + HCl v RNH 3 Cl s/l RNH 3 Cl s/l + H 2 O RNH + 3 aq + Cl (aq)

4 Refinery overhead corrosion Root Cause of Failures: 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. OLI Systems Mixed-Solvent Electrolyte (MSE) model: Phase equilibria in mixtures containing various amines, ammonia, HCl, CO 2, H 2 S, water and hydrocarbons. The model predicts the formation of solid salts or concentrated amine hydrochloride solutions that may induce corrosion.

5 Mixed-solvent electrolyte model (MSE): Thermophysical Framework Excess Gibbs energy model Gas-phase equation of state Thermochemistry of species Standard-state properties of solution species Themodynamic framework Adsorption models Phase and chemical equilibrium algorithm Transport properties and surface tension Applications (process, corrosion, oilfield scaling, etc.)

6 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

7 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

8 Outline of the model: Solution nonideality LR LC II Excess Gibbs energy ex G RT ex LR G RT ex LC G RT ex GII RT Debye-Hückel theory for long-range electrostatic interactions Local composition model (UNIQUAC) for neutral molecule interactions Ionic interaction term for specific ion-ion and ionmolecule interactions G ex II RT ni i i j x i x j B B ij I ( I x ) b ion interaction parameters c exp( I a ij x ij ij x 1 )

9 Outline of the model: Chemical equilibrium calculations For a sample chemical reaction: aa At equilibrium 0 G RT bb x ln x c C a A cc x x d D b B c C a A dd d D b B with Standard-state chemical potential of i 0 0 G v 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 i i i

10 MSE-AmineHCL Databank Thermodynamic Framework Mixed-solvent electrolyte model (MSE) Subset of the chemistry of interest (i.e., CO 2, H 2 S, H 2 O, NH 3, HCL, NH 4 CL, 56 Hydrocarbons and selected mixtures) MSE Databank Parameters for amine hydrochlorides AmineHCL Databank MSE Databank Private databank, available only to consortium members until November 15, 2014 New MSE databank, available from November 15, 2014

11 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

12 Amines and Amine hydrochlorides Methylamine CH 3 NH 2 Dimethylamine (CH 3 ) 2 NH Trimethylamine (CH 3 ) 3 N Ethylamine CH 3 CH 2 NH 2 Diethylamine CH 3 CH 2 NHCH 2 CH 3 Propylamine CH 3 (CH 2 ) 2 NH2 Butylamine CH 3 (CH 2 ) 3 NH2 2-Butylamine CH 3 CH 2 CH(CH 3 )NH 2 Cyclohexylamine c-(ch 2 ) 5 CHNH 2 Ethylenediamine H 2 N(CH 2 ) 2 NH 2 Morpholine c-(ch 2 ) 2 O(CH 2 ) 2 NH N-Methylmorpholine c-(ch 2 ) 2 O(CH 2 ) 2 NCH 3 N-Ethylmorpholine c-(ch 2 ) 2 O(CH 2 ) 2 NC 2 H 5 Ethanolamine (MEA) HO(CH 2 ) 2 NH 2 Diethanolamine (DEA) HO(CH 2 ) 2 NH(CH 2 ) 2 OH Dimethylethanolamine (DMEA) (CH 3 ) 2 N(CH 2 ) 2 OH Diglycolamine (DGA) HO(CH 2 ) 2 O(CH 2 ) 2 NH 2 N-Methoxypropylamine H 2 N(CH 2 ) 3 OCH 3 Dimethylisopropanolamine HOCH(CH 3 )CH 2 N(CH 3 ) 2 Methyldiethanolamine (MDEA) CH 3 N(C 2 H 4 OH) 2

13 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 Heat capacities Critical properties Critical temperature Critical pressure Critical volume Densities Molar volume Amines in the gas phase Amines in the liquid phase Solid amine hydrochlorides Gaseous amines Liquid amines Solid amine hydrochlorides Amines Pure liquid amines Solid amine hydrochlorides Van der Waals surface & area parameters Liquid amines

14 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

15 Which parameters were regressed for amines? Standard-state Gibbs energy ( f G o ) Absolute entropy (S o ) Aqueous amines & Corresponding amine-h + ions HKF parameters For all aqueous species (neutral or ionic ) Maximum 7 parameters in the model 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 Amine-H + ions Amines and water Amines and hydrocarbons Aqueous solution of amines

16 Which parameters were regressed for amine hydrochlorides? Standard-state Gibbs energy ( f G o ) Absolute entropy (S o ) 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)

17 logkb Hydrolysis reaction constants: AMINE +H 2 O = AMINE-H + + OH Hydrolysis constants (K b ) for all 20 amines in water (temperature range from 0 to 300 o C) -3 sec-butylamine Propylamine logkb Ref. 1 Ref. 2 Calc t / C Ref. 1 Ref. 2,6 Ref. 3,6 Ref. 4,6 Ref. 5,6 Ref. 9 Ref. 8 Calc. t / C

18 ph: Amine solutions ph values were measured at SwRI for 10 aqueous amine solutions as a function of temperature N-Methylmorpholine C, ref. 1 Calc. Diglycolamine ph 9.5 ph I=0.01,0.002 m I=0.05, m I=0.25, m I=0.01, 0.01 m I=0.05, 0.01 m I=0.25, 0.01 m I=0.01, 0.05 m I=0.05, 0.05 m I=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 m NMM - ref m NMM - calc t / C X DGA

19 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). P / atm C: 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 60C - calculated 78C - calculated 91.7C - calculated Ethanolamine 35C - calculated 70C - calculated 90C - calculated X MEA P MEA / atm Ethanolamine t / C 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= calculated X= calculated X= calculated X= calculated X= calculated X= calculated X= calculated X= calculated X= calculated X= calculated X= calculated X=1 - calculated

20 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). P (atm.) sec-butylamine P / atm X= X= X= X= X= X= X=1 X= calc. X= calc. X= calc. X= calc. X= calc. X= calc. X=1-calc. sec-butylamine C - ref. 1 10C - ref. 1 20C - ref. 1 30C - ref. 1 40C - ref. 1 50C - ref. 1 60C - ref. 1 70C - ref. 1 80C - ref. 1 90C - ref. 1 0C - calc. 0C - Y 10C - calc. 10C - Y 20C - calc. 20C - Y 30C - calc. 30C - Y 40C - calc. 40C - Y 50C - calc. 50C - Y 60C - calc. 60C - Y 70C - calc. 70C - Y 80C - calc. 80C - Y 90C - calc. 90C - Y X sec-buam t / C

21 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). 0.8 N-Methylmorpholine 40C-ref.2 50C-ref.2 60C-ref.2 70C-ref.2 80C-ref N-Methylmorpholine 0.25 atm. - ref atm. - ref atm. - ref atm. - calc atm. - calc atm. - calc atm. - Y 0.39 atm. - Y 0.59 atm. - Y 90C-ref C-calc. P / atm C-calc. 60C-calc. 70C-calc. 80C-calc. 90C-calc. 40C-Y 50C-Y 60C-Y t / C X NMM 70C-Y 80C-Y 90C-Y X NMM

22 Caloric properties: Aqueous amine solutions Heat capacity was measured as a function of temperature and concentration. Cp (cal/gk) Diethanolamine 30C-ref. 1 35C-ref. 1 40C-ref. 1 45C-ref. 1 60C-ref. 1 50C-ref. 1 65C-ref. 1 55C-ref. 1 70C-ref. 1 75C-ref. 1 80C-ref. 1 25C-ref. 2 20C-ref. 3 50C-ref. 3 30C-ref. 3 60C-ref. 3 40C-ref. 3 70C-ref. 3 80C-ref. 3 10C-ref. 4 90C-ref. 3 25C-ref C-ref.3 40C-ref. 4 55C-ref. 4 10C - calc. 20C - calc. 25C - calc. 50C - calc. 30C - calc. 60C - calc. 40C - calc. 70C - calc. 80C - calc. 90C - calc. 100C-calc X DEA

23 Amine hydrocarbon systems: Liquid-liquid equilibria (LLE) MSE model is capable of reproducing more complex phase behavior (i.e., VLE, VLLE and LLE) in the whole concentration range. Diethanolamine + Hexadecane 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 X DEA

24 Amine CO 2 H 2 O systems: VLE for Ethanolamine (MEA) + CO 2 + H 2 O MSE model is capable of reproducing the behavior of the amine-co 2 -H 2 O ternary system essentially within the scattering of experimental data. PCO2 (atm) N, 15.2 wt%, 2.9 m CO 2 / MEA (mol/mol) 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) - smoothed 100C: Lee et al.(1976) - smoothed 25C - calculated 30C - calculated 40C - calculated 60C - calculated 80C - calculated 100C - calculated 120C - calculated 140C - calculated

25 Amine H 2 S H 2 O systems: VLE for Ethanolamine (MEA) + H 2 S + H 2 O MSE model reproduces the behavior of the amine-h 2 S-H 2 O ternary system consistently well. Total pressures can be reproduced more accurately than partial N, 7 m, 30 wt% 1 PH2S (atm) C: 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 - calculated 100C - calculated 120C - calculated H 2 S / MEA (mol/mol)

26 Amine H 2 S CO 2 H 2 O systems: VLE for Diethanolamine (DEA) + H 2 S + CO 2 + H 2 O MSE model reproduces partial pressures of CO 2 and H 2 S for amine-h 2 S-CO 2 -H 2 O quaternary system within their experimental uncertainty. 40C: Jane&Li(1997), 30 w% 80C: Jane& Li(1997), 30 wt% 40C: 100 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 10 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 1 Pcalc (atm) H 2 S partial pressures P exp (atm)

27 Sublimation data: Pure amine hydrochlorides Vapor-solid transitions of pure amine hydrochlorides as a function of temperature. SLE and VLE data for amine hydrochlorides-water systems are available. 1.E+00 1.E-01 p[atm] Methylamine hydrochloride 1.E-02 1.E-03 p[atm] Morpholine hydrochloride 1.E-02 1.E-03 1.E-04 1.E-04 1.E-05 1.E-05 1.E-06 1.E-07 1.E-08 1.E-09 MSE liquid MSE solid Aston&Ziemer 1946 Kisza E-06 1.E-07 1.E-08 1.E-09 MSE liquid MSE solid Bannard&Casselman 1965 Fearnside 1998 Lehrer&Edmondson 1993 Lehrer&Edmondson 1993, rescaled 1.E-10 1.E t[c] t[c] 300

28 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.

29 PRO/II Thermodynamic data Selecting Electrolyte category from PRO/II property calculation system and adding the databank (*.dbs) file to include the chemistry.

30 PRO/II Flowsheet PRO/II flowsheet is ready with the new chemistry model.

31 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 Upcoming presentations by Shell, Phillips 66, and Athlon at the OLI Simulation Conference, OLI is forming special interest group to guide further development of refinery overhead simulation technology.

32 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, CO 2, H 2 S, water and hydrocarbons The model predicts the formation of solid salts or concentrated amine hydrochloride solutions that may induce corrosion

33 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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