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Amine gas treatmentgas sweetening; acid gas removalrefers to a group of processes that use aqueous solutions of various alkylamines (RNH2) to removehydrogen sulfide(H2S) andcarbon dioxide(CO2) from gases

Diethanolamine(DEA)Monoethanolamine(MEA)Methyldiethanolamine(MDEA)Diisopropanolamine(DIPA)Aminoethoxyethanol (Diglycolamine) (DGA)

MEA (Monoethanolamine)Used in low pressure natural gas treatment applications requiring stringent outlet gas specificationsMDEA (Methyldiethanolamine)Has a higher affinity for H2S than CO2 which allows some CO2 "slip" while retaining H2S removal capabilities.DEA (Diethanolamine)Used in medium to high pressure treatingdoes not require reclaiming, as do MEA and DGA systems.FORMULATED (SPECIALTY) SOLVENTSA variety of blended or specialty solvents are available on the marke

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In oil refineries, that stripped gas is mostly H2S, much of which often comes from a sulfur-removing process calledHDS. This H2S-rich stripped gas stream is then usually routed into aClaus processto convert it into S.

In fact, the vast majority of the 64,000,000 tons of S produced worldwide in 2005 was byproduct sulfur from refineries and other hydrocarbon processing plants.The amine concentration in the absorbent aqueous solution is an important parameter in the design and operation of an amine gas treating process.The choice of amine concentration in the circulating aqueous solution depends upon a number of factors and may be quite arbitrary. It is usually made simply on the basis of experience.Ph thuc ngun kh u vo -> nng H2S, CO2in an amine treating unit, CO2is the stronger acid of the two. H2S forms a film of iron sulfide on the surface of the steel that acts to protect the steel. When treating gases with a high percentage of CO2, corrosion inhibitors are often used and that permits the use of higher concentrations of amine in the circulating solution.4ADIP PROCESSThe ADIP process covers the use of the aqueous solution of diisopropanol amine (DIPA) and the aqueous solution of methyldiethanol amine (MDEA).Absorber operating pressure can be up to 150 bar. Gas temperature can vary from ambient up to 60C. More than 450 ADIP units ranging in capacity from 1.900 Nm3/d to 12.200.000 Nm3/d are in operation throughout the world.

5H2S Treatment locationsOilfield Can be treated at Wellheads Transshipment Treated at Load port Refinery Treated at Refinery TerminalTreatment during offloading In Refinery treatmentTypically products treated as needed Downstream Downstream product treatment

Load portCng6Chemical Removal of H2SOxidizers Neutralizers (organic amines, inorganic bases)Metals Reactants Organic Bases Triazines Formaldehyde, Acrolein Effective in a wide range of fuelsMinimizes number of additives neededReduces product rejections and shipping delaysReduces additive odor, corrosion and safety problemsOxidizersAmine NeutralizersInorganic Bases Very fast Water soluble products, sulfites Fast reaction No sodium lower-temperature applications

Fast reaction, cheap Use alone or in combination Thermally stable products Dangerous Explosive not selective for S compounds - react with other components of the oilNot used Reaction is reversible Weak acid/base equilibrium regenerate H2S under certain conditions Wastewater effects increased nitrogen Non-selective for H2S Reaction is reversible Ash forming Increases fuel sodium content Limited safe injection temperatureSpecialty chemical conversion reagents(Scavenger)This type of additive reacts with H2S irreversibly to form thermally stable reaction products Economical costs and fast reaction

Water-soluble scavengersOil-soluble scavengersMetal-based scavengersNon-nitrogen and polymeric aqueous-based scavengers are also available.

Water-soluble scavengersthe most common scavengers often the product of choice for applications at temperatures below 200F (93C). Economical costs and fast reaction Moreover, due to their water solubility, they add a minimum amount of nitrogen to the fuel. A common type of water-soluble H2S scavenger is a triazine-based chemistry.

By reducing the concentration of H2S in storage tank headspace, use of an H2S scavenger reduced corrosion rates measured on the tank roofs from nearly 14 to < 1 mils per year (0.36 to 0.0254 mm per year).

Oil-soluble scavengersOil-soluble scavengers are used in high-temperature applications from ambient up to 350F (177C) or when water tolerance of the hydrocarbon is an issue. These products are typically amine based and perform as effectively as water-soluble additivesthe product of choice for viscous heavy oils and resinsMetal-based scavengersMetal-based scavengers answer the specific needs of very high temperature and high-H2S concentration applications. provide H2S reduction levels that other H2S scavengers cannot achieveincreased reactivity with H2SH2S + SULFIX product Inert S species(Baker Huges) Advantages: Non-reversible at typical usage temperatures Rapid reaction depending on mixing and dosage Selective for H2S May be used at high temperature and with caustic (KOH, NaOH) Extensive no-harm testing Successful industry track-record Effective in wide range of fuels UOP Amine Guard FS processUCARSOL (MDEA based solvent) Features:High thermal and chemical stabilityNon-corrosive (no corrosion inhibitors needed) achieve very low residual H2S & CO2 content of product gasNon foaming

Conventional (absorber + thermal regeneration)

Can achieve CO2levels below 50 ppm for LNG specificationsLower solvent requirements than flash-only systemThermal regeneration for higher level of removal17SulfaTreat (Schlumberger)A blend of iron oxidesThe process is a fixed bed system for treating gas or vapor streams