Optimization of Process Design and Operating Parameters of H2S Removal Unit to Reduce Lean Amine Inlet Temperature of Amine Contactor at Upstream Oil and Gas Subsidiary SI

Abstract

Upstream Oil and Gas Subsidiary SI is a natural gas processing company that operates an H₂S removal unit to convert natural gas rich in CO₂ and H₂S into sweet gas. The main problem of this unit is the high temperature of Lean amine coming into contact with the amine contactor. The purpose of this study is to determine the factors of high lean amine temperatures, evaluate the Lean Amine Cooler, Amine Regenerator Overhead Cooler, and Plate Exchanger performance, and ascertain the ideal operating parameters and process design configuration. The method used is simulation of H₂S removal unit with Aspen HYSYS, followed by comparative analysis between simulation data and equipment design data. The independent variables of this study include rebate duty, reflux ratio, and heat transfer area in the plate exchanger, with the primary dependent variable being lean amine temperature. The results showed that the high lean amine temperature was caused by a decrease in the performance of The Amine Regenerator Overhead Cooler and the Lean Amine Cooler, as seen from the UA and LMTD values of the simulation results which were smaller than the design. In contrast, the Plate Exchanger still functions well with a UA value that is more significant than the design. Optimization was carried out by adjusting the process criteria for design and operation of the H₂S removal unit. The optimized design involves bypass reflux from the Rich/Lean Amine Exchanger's regenerator for the rich amine stream and increasing the surface area of heat transmission of the Plate Exchanger to 62.17 m². The influential operating parameters are rebate duty, liquid flow rate to the mixer, and plate exchanger heat transfer surface area. Optimal operating conditions were achieved at a Reboiler duty of 1,642 kW, a liquid flow rate of 1.4 m³/h, reflux to Mixer ratio, and a heat transfer surface area of 62.17 m². In addition, it can be concluded that the optimization of process design and operating parameters successfully reduced the lean amine inlet temperature of the Amine Contactor.