Khangiran sour gas refinery was originally founded in late 1970 decade and commissioned in early 80 s. The original plant consisted of three gas treating units (GTU) refining around 30 MMSCMD Mozdouran reservoir sour gas at the peak capacity. The refinery production rate was increased to 50 MMSCMD at the beginning of new millennium by constructing two additional GTUs. All sweetening units were designed using 34% DEA in water as the solvent. The amine was replaced by 45% MDEA solution, recently . The dry sour gas analysis (prepared by Amine Expert Company on 9th Feb. 2004) for the contactor feed of the Khangiran GTUs [1] were used. For all simulations, the dry gas was initially saturated with water before entering the GTU process. The average molecular weight of C6+ was computed about 156, based on RIPI report [1]. The sour gas contains about 10% carbon dioxide and hydrogen sulfide which should be separated using suitable amine solution in an absorption tower. The performance of amine contactor column is highly sensitive to the entering temperature of both sour gas and lean solvent. The optimal absorption temperature of H2S and CO2 by DEA solution is about 38°C and 49°C, respectively [2]. The operational temperature for MDEA solvent is usually about 50°C [3]. Evidently, increasing the entering gas and liquid temperatures boost the maximum peak inside the absorber to a value, which is quite close to the stripping temperature of hydrogen sulfide.

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