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

Chemistry in Refining Overheads 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 CTW, September 2006 Chemistry in Refining Overheads

Chemistry in Refining Overheads 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 CTW, September 2006 Chemistry in Refining Overheads

Chemistry in Refining Overheads 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 CTW, September 2006 Chemistry in Refining Overheads

Chemistry in Refining Overheads 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 CTW, September 2006 Chemistry in Refining Overheads

Chemistry in Refining Overheads What is needed -> The amine system parameters for the model To obtain the parameters Experimental work measure amine-HCl salt data where no published / literature data exists Data development work develop a thermo-physical property database for the amine-HCl salts Once obtained Application development set up cases to calculate sublimation point and dew point …For user-defined refining overhead streams, of varying compositions CTW, September 2006 Chemistry in Refining Overheads

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 CTW, September 2006 Chemistry in Refining Overheads

Mixed Solvent Electrolyte Model Key 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 CTW, September 2006 Chemistry in Refining Overheads

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 CTW, September 2006 Chemistry in Refining Overheads

Chemistry in Refining Overheads 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 CTW, September 2006 Chemistry in Refining Overheads

Approach: 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 CTW, September 2006 Chemistry in Refining Overheads

Chemistry in Refining Overheads 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 CTW, September 2006 Chemistry in Refining Overheads

Example systems, NH4Cl & NH4HS Solid-gas equilibrium computations for pure NH4Cl and NH4HS NH4Cl NH4HS CTW, September 2006 Chemistry in Refining Overheads

Chemistry in Refining Overheads 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 CTW, September 2006 Chemistry in Refining Overheads

Chemistry in Refining Overheads Status JIP underway SwRI is the experimental partner Amine list has being compiled Equipment has been designed Literature search is nearly complete CTW, September 2006 Chemistry in Refining Overheads

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 CTW, September 2006 Chemistry in Refining Overheads

Amines to be studied – next 8 Methylamine Methyldiethanolamine MDEA Ethylamine N-methylmorpholine Diglycolamine DGA Diethylamine N-butylamine Sec-butylamine CTW, September 2006 Chemistry in Refining Overheads

Chemistry in Refining Overheads Questions? Thanks for your attention! CTW, September 2006 Chemistry in Refining Overheads