Crude Unit Overhead Modeling The technology that makes it possible

1. Crude Unit Overhead Modeling The technology that makes it possible Chemistry in Refining OverheadsA Focus Group of the OLI MSE Consortium 2006 – 2008 Pat McKenzie, AQSim Jim Berthold, OLI CTW, September, 2006

2. Motivation • This project will address a major cause of overhead corrosion, the formation of amine chloride salt deposits Overview • Project background • Project approach • Status • Amine list • Questions Chemistry in Refining Overheads

3. Business Case • Corrosion source Amine-HCl salt deposits on hot metal surfaces • Prevention Prevent salt formation • Method Operate refinery unit above “salt point” T • Challenge What is a safe temperature? • Solution Predict sublimation point and dew point Ts in mixtures • Opportunity This Focus Group Chemistry in Refining Overheads

4. Goal • The goal of this project is to simulate the behavior of overhead refining streams • This will enable the simulation software users to determine optimal operating conditions, in order to minimize - or to prevent - the deposition of amine chloride salts in the overheads • For “typical” overhead chemistry • H2O • Sulfides, sulfates • Chlorides • NH3 and the amines • Light hydrocarbons Chemistry in Refining Overheads

5. Available technology • Electrolyte simulation is the core competency(a.k.a. ionic modeling) • Simulation techniques • Behavior of electrolytes – acid/base chemistry • Existing thermodynamic frameworks for ionic modeling can predict • Dew points • Sublimation points (“salt point”) • General phase equilibrium behavior for systems containing electrolytes and non-electrolytes Chemistry in Refining Overheads

6. What is needed -> The amine system parameters for the model • To obtain the parameters • Experimental workmeasure amine-HCl salt data where no published / literature data exists • Data development workdevelop a thermo-physical property database for the amine-HCl salts • Once obtained • Application developmentset up cases to calculate sublimation point and dew point …For user-defined refining overhead streams, of varying compositions Chemistry in Refining Overheads

7. Mixed Solvent Electrolyte Model:a new thermodynamic model • This work requires OLI’s newer mixed solvent electrolyte (MSE) framework • Amine-rich dew points are beyond the concentration limit of OLI’s aqueous model: 30 molal ionic strength • Sublimation as a phenomenon is only available in the MSE model, not the aqueous model Chemistry in Refining Overheads

8. Mixed Solvent Electrolyte ModelKey points to remember • Predicts water chemistry speciation • vapor, solid, aqueous, 2nd liquid phase • Predicts behavior of many electrolyte solutions • Dilute solutions, solid saturation, pure salts, pure solutes • Electrolytes in organic solvents • Water-organic-salt systems in the full range of concentrations • At temperatures up to 90% Tcrit of the mixture • Predicts based (primarily) on binary interactions • Predictions, not interpolations Chemistry in Refining Overheads

9. Advantages of the MSE framework • No local modeling is needed • Adding components to a system is handled without further data refitting (provided they are in the database already) • No local optimization is needed • Modification of k-values or vapor pressure coefficients (e.g., Antoine) is a common practice in some models, not required in the MSE model • Some systems benefit from ternary interaction parameters • Example: I2, HI, H2SO4 – needed the ternary • This is not expected in for the amine systems Chemistry in Refining Overheads

10. Past work • Shell Global Solutions, Inc. • Made some of these measurements • Used OLI’s previous, aqueous model to regress parms • Univ of Alberta - gas sweetening operations • Amines, water, CO2, H2S, and some HCs • Left out the critical (to us) HCl component Learning from past work • Work will be done in high-concentration model • Past experience in measurements will be used • Literature – public - data used wherever possible Chemistry in Refining Overheads

11. Approach: Experimental work • Experimental work • Vapor-Liquid Equilibrium (VLE) • Solid-Liquid Equilibrium (SLE) • Titration measurements (for ionization of amines) • Calorimetric measurements (melting points, heat cap) • Avoid direct sublimation point measurements • Sublimation equipment is expensive, more risk • VLE, SLE measurement equipment “off the shelf” • Potential corrosovity creates special needs • SwRI factored this into the design of equipment Chemistry in Refining Overheads

12. Data development work • Work will include • Literature searches for any available data • Specification of data to measure experimentally • Data regressions of compiled data into the model • For a particular amine, constituent subsystems would be: • Amine • Amine + water • Dissociation behavior between the amine and the ionized form of the amine • Amine + water + CO2 + H2S • Amine hydrochloride + water Chemistry in Refining Overheads

13. Example systems, NH4Cl & NH4HS Solid-gas equilibrium computations for pure NH4Cl and NH4HS NH4Cl NH4HS Chemistry in Refining Overheads

14. VLE for NH3 – H2S – H2O Accurate representation of solid-gas equilibria for NH4HS and nonideality of the NH3 – H2S – H2O ternary should ensure correct predictions of solid-gas-liquid equilibria in the ternary system Chemistry in Refining Overheads

15. Status • JIP underway • SwRI is the experimental partner • Amine list has being compiled • Equipment has been designed • Literature search is nearly complete Chemistry in Refining Overheads

16. Amines to be studied – 1st 10 • Trimethylamine TMA • Cyclohexylamine • 3-methoxypropylamine MOPA • 2-dimethylaminoethanol DMEA • Diethanolamine DEA • Dimethylisopropanolamine DMIPA • Dimethylamine DMA • Ethylenediamine EDA • Monoethanolamine MEA • Morpholine Chemistry in Refining Overheads

17. Amines to be studied – next 8 • Methylamine • Methyldiethanolamine MDEA • Ethylamine • N-methylmorpholine • Diglycolamine DGA • Diethylamine • N-butylamine • Sec-butylamine Chemistry in Refining Overheads

18. Questions? Thanks for your attention! Chemistry in Refining Overheads