gas treatment – What Is Piping: All about Piping Engineering

Gas sweetening process is the method removing Hydrogen Sulfides, Carbon Dioxide, and Mercaptans from natural gas to improve its quality and make it suitable for transport and sale. These elements are corrosive and toxic in nature and should be removed. Reasons for Gas Sweetening Process Removal of the contaminants from Gas are required for reason of: Corrosion ControlToxicityGas/ Liquid product specificationsTo prevent poisoning of catalyst in downstream facilitiesControl of the overall heating value of the natural gasTo meet environmental requirements CO2 & H2S are very common contaminants in Natural Gas system Reason for CO2 Removal for Gas Sweetening: When combined with water forms Carbonic Acid which is corrosiveCO2 reduces the BTU value of the gasIf present in 2-3% gas is not saleable. Reason for H2S Removal for Gas Sweetening: Extremely toxic gasHighly corrosive Reason for Mercaptans (R-SH) Removal for Gas Sweetening: It has smellIf comes in contact with bacteria (inside the final product storage) then released H2S2R-SH Bacteria R-SSR + H2S Gas Sweetening Process Treatment – Process Selection Air pollution regulations regarding Sulfur Compound disposal and/or Tail gas clean-up requirementsType & concentration of Impurities in sour gasTemp/pressure at which sour gas is available and at which sweet gas must be deliveredSpecification for the Acid gasSpecification for the Residue gasHydrocarbon composition of the gasSelectivity required for Acid Gas removalCapital cost and operating cost Chemical Reaction Process (Continuous) for Gas Sweetening Amine Process MEA (Mono ethanol Amine)DGA (Diglycolamine)DEA (Diethanol Amine)MDEA (Methyl Dethanol Amine)DIPA (Diiso Propanol Amine)Formulated Amines (Proprietory Amines)Mixed Amines Physical Solvents (Absorption) Selexol (DOW process)Fluor Solvent Application of Physical Solvent Consider when Partial pressure of acid gas > 50psiHeavy HC concentration is lowBulk removal of acid gas requiredSelective removal of H2S is required Advantages of Combination Process Can achieve 30ppm of CO2 and 1ppm of H2SLow Energy requirementLow foaming & non-corrosiveHigh acid gas loading Combination of Chemical + Physical Solvents SULFINOL-M (Sulfolane + MDEA)SULFINOL-D (Sulfolane + DIPA)UCARSOL (Formatted MDEA based Solvent) Other Methods Molecular SieveLocatSulferox Physical Solvent v/s Chemical Solvents Evaluation of Process Note: Acid gas (H2S+CO2+CS2+COS+RSH)Acid gas pick-up – Mole of Acid gas removed in RegeneratorAcid gas loading – Quantity of Acid gas absorbed in the Amine Solution Process Capabilities Sulfinol (SHELL TECHNOLOGY) Process of Gas Sweetening Solvents: Sulfinol-M {Sulfolane (20%)+MDEA (50%)+Water (30%)}Sulfinol-D {Sulfolane (20%)+ DIPA (50%)+Water (30%)}Sulfinol-X  Improved Sulfinol M & Sulfinol D with an Acceleration Agent Note: Sulfolane – Tetrahydro Thiophene Dioxide (Physical Solvent) Merits of Sulfinol Process Higher Acid Gas loading (typical 1.5 Mole of AG/Mole of Sulfinol)Lower corrosion RatesAbility to slip up to 50% CO2 (Selective removal of H2S from gas FEED containing CO2)Lower solvent rateLower Energy of RegenerationLower capital & Energy / Operating cost per unit of Acid Gas removedComplete removal of mercaptansThe high removal rate of COSLower foaming tendencyCan be used for wide range of operating pressure (up to 80 bar)Sulfolane increases the physical solubility of the acid gas contaminants in the solventSulfolane improves the efficiency of the absorption processPhysical solubility of Mercaptants increases. De-merits of Sulfinol Process Payment of Licensing feeThe solvent is costlier than chemical solventsAt low acid gas partial pressure, the advantage of a lower circulation rate for the Sulfinol process diminishes as compared to chemical solvents.