Ali farrokhi - SPGC Senior Process Engineer
Reza Babaei - SPGC Process Engineer

Gas sweetening units of SPGC(south pars gas company)were designed by French ELFCO.MDEA(which is Methyl DE-Ethanol Amine, as selective for H2S removal) uses totreat sour gas with around 5500ppmH2S&1.8%vol CO2 and sweet gas specificationare 3 ppmmol H2S &1.5%vol CO2. design amine circulation flow rate is 250 m3/hwith 45%wt concentration.We had high rate of CO2 co-absorbtion in amine absorber instead of higher rate of H2S absorbtion and so high H2S &low CO2 contents were problems in beginning of phase 2/3 start up with too low H2Scontent of acid gas to SRU(sulfur recovery units).During start up in 2002 the lean amine flow rate was decreased to 135 m3/h(optimum flow rate found after some simulation,investigation & test run) to have on spec sweet gas. Then in order to optimize process conditions espicially the utilities consumption, some HYSYS simulation & test run were done and total HPsteam saving of 1248 tons per day and power saving of 213 kw per day have been achieved in 4 gas trains of phases 2 & 3 due to lower required temperature of amine regeneration (optimum amine regenerator bottom temperature of 131.5 C). Optimum amine circulation rate found 135 m3/h in order to have on spec sweet gas(<3 ppm H2S & <1.5%vol CO2) and to have lower energies consumption in amine regeneration section (sream of amine reboiler & power of regenerator reflux air cooler).Results are applicable for phase-1 and phases 4&5 gas sweetening units.

Optimisation, Energies saving, MDEA Gas sweetening