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Keywords
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Gas sweetening, Absorption, Promax simulation, Hydrogen sulfide (H2S), Carbon dioxide (CO2)
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Abstract
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The selective removal of acid gases using amine-based solutions is a significant process in the petroleum and natural gas industries. This work investigates the effectiveness of two common chemical solvents of Methyl Diethanolamine (MDEA) and Diethanolamine (DEA) and the blends of them with different mass concentration and circulation rate to absorb H2S and CO2 from natural gas in an existing industrial process plant in Phase I of the South Pars Gas complex (SPGC) located in Persian Gulf region. This sweetening unit was simulated for H2S-CO2-MDEA-H2O and H2S-CO2-DEA-H2O systems that are incorporated into the Amine Package in Promax simulator. Sensitivity analysis were performed on circulation rate (140-350 m3/hr for MDEA and 300-520 m3/hr for DEA), concentration (30-65 wt.% for MDEA and 30-40 wt.% for DEA) of amine solution and the MDEA to DEA ratio (eight different cases) which are the main factors improving process performance. The effect of these factors has been separately studied on the parameters such as acid gas content in the sweetened gas, reboiler duty, acid gas loadings, amine carryover and pH. The results confirmed that higher solvent concentration and circulation rate are beneficial to the sour gas absorption process. However, they require a greater corresponding energy to regenerate rich-loaded solution in the reboiler. It enhances the operational costs. Based on the results, the optimal concentration and flow rate of MDEA and DEA solvents was obtained 40 and 32 wt.% and 150 and 350 m3/hr, respectively.
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