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Licensed Unlicensed Requires Authentication Published by De Gruyter January 25, 2020

Simulation of an Acid Gas Removal Unit Using a DGA and MDEA Blend Instead of a Single Amine

Umer Zahid ORCID logo

Abstract

Most of the industrial acid gas removal (AGR) units employ chemical absorption process for the removal of acid gases from the natural gas. In this study, two gas processing plants operational in Saudi Arabia have been selected where two different amines n1amely, diglycolamine (DGA) and monoethanol amine (MDEA) are used to achieve the sweet gas purity with less than 4 ppm of H2S. This study performed a feasibility simulation of AGR unit by utilizing the amine blend (DGA+MDEA) for both plants instead of a single amine. The study used a commercial process simulator to analyze the impact of process variables such as amine circulation rate, amine strength, lean amine temperature, regenerator inlet temperature, and absorber and regenerator pressure on the process performance. The results reveal that when the MDEA (0–15 wt. %) is added to DGA, marginal energy savings can be achieved. However, significant operational energy savings can be made when the DGA (0–15 wt. %) is blended with MDEA being the main amine.

Acknowledgements

The authors would like to acknowledge financial support from King Fahd University of Petroleum & Minerals (KFUPM).

Appendix

A

For equilibrium reactions, Aspen HYSYS provides a built-in expression for calculating equilibrium constants:

lnKeq=A+BT+ClnT+DT

Table 6:

Parameters of the equilibrium constant of reactions used in the simulation.

ReactionABCD
H2O + DGAH+ ⇌ DGA + H3O+1.6957−8431.650−0.005037
H2O + MDEAH+ ⇌ MDEA + H3O+−9.4165−4234.9800
2 H2O ⇌ H3O+ + OH132.8990−13445.90−22.47730
H2O + HCO3 ⇌ H3O+ + CO3−2216.0490−12431.70−35.48190
H2O + H2S ⇌ H3O+ + HS214.5820−12995.40−33.54710
H2O + HS ⇌ H3O+ + S−2−9.7420−8585.4700

Nomenclature

AMP

2-amino-2 methyl-1-propanol

DEA

Diethanolamine

DGA

diglycolamine

EOR

Enhanced oil recovery

eNRTL

Electrolyte nonrandom two liquids

HHV

High heating value

KGP

Khursaniyah Gas Plant

MDA

1,8-p-methanediamine

MDEA

Methyl diethanolamine

MEA

Monoethanol amine

PE

2-piperidiene ethanol

PR

Peng Robinson

SAFT-VR

Statistical Associating Fluid Theory with variable range

SGP

Shedgum Gas Plant

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Received: 2019-03-19
Revised: 2019-12-10
Accepted: 2019-12-13
Published Online: 2020-01-25

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