: Natural gas is considered as a clean fuel gas in comparison with other fossil fuels.  The Natural gas found in the reservoirs is not purely clean but it consists of different contaminants such as H₂S, CO₂, He, Hg, N₂, and water and some hydrocarbons such as lighter and heavier hydrocarbons.  About 40% of the world remaining gas reservoirs contains impurities like H₂S, CO₂ and sulfinol.  Many large oil and gas fields have more than 10 mole % CO₂ and H₂S content.  For injection into pipelines and equipment, the untreated natural gas must be treated in order to meet the pipelines and equipment’s quality standards specifications for consumer gas, to prevent them from corrosion and to achieve the standard transport requirements.

In this research a process simulation model was developed on the basis of the real plant data obtained from the gas cleaning facility located at jhand, Punjab [Pakistan] for the removal of acid gases such as H₂S and CO₂ using absorption process in Aspen HYSY simulation software v9.0.  In absorption process the solvent used generally is MDEA for the selective removal of H₂S but it removes CO₂ at slower rate.  Piperazine when blended with MDEA solution increases the rate of absorption of CO₂ from natural gas and increase the removal efficiency of acid gas by 0.87% when the total numbers of trays were equal to 31.  Two different process simulation models were developed for acid gas removal using Aspen HYSYS for two different solvents i-e MDEA and Piperazine activated MDEA solution.  The process simulation model based on MDEA as a solvent was compared and validated with the actual plant data.  The Aspen HYSYS process simulation software v9.0 worked great with the actual plant data and the results were in agreement with each other within +-17% error.  The two simulation models were then compared for the removal of acid gases efficiency.  The process simulation models based on Piperazine blended with MDEA have shown that they have higher efficiency of 8% especially for CO₂ removal in comparison to the use of MDEA alone as a solvent when the total numbers of trays used were decreased from 31 to 20.