Simulated Design for the Removal & Recycling of Acid Gases from Natural Gas

Natural gas is one of the major sources of fuel and raw material to industries all over the world. However, it contains some acid gases such as CO2 and H2S which are corrosive and harmful to the environment. These acid gases must be brought to permissible limits to promote safety in the operation and increase the heating value of the natural gas. In this project, we design an acid gas removal plant based on the amine treatment process using ASPEN HYSYS software.   

      In our proposed design, a counter-current flow occurs between the rising sour gas and the descending methyldiethanolamine (MDEA), thereby, absorbing the acid gases. MDEA is recycled back to the absorber column, while the acid gases are separated into their respective components of CO2 and H₂S respectively. CO2can be used for enhanced oil recovery while H₂S can be used in petrochemical processes such as production of rubber, sulfuric acids and medicines.

          The use of activated MDEA for the acid gases absorption, which encapsulates a combination of two different amines, say MDEA and DEA, is recommended for future developments of this project. The total utilities and installed cost for our proposed natural gas sweetening plants are $1,315,710 and $1,671,800 respectively.

Table of Contents

Abstractiii

Acknowledgementsiv

List of Tablesv

List of Figures

1.     Introduction. 1

1.1.     Scope and Limitation(s)2

2.     Motivation/Objective of the Study. 4

3.     Literature Review.. 4

4.     Methodology. 7

5.     Process Description. 8

5.1.     Qualitative Description of Process Equipment11

5.1.1. Two-Phase Separator (V-100)11

5.1.2. Absorber Column (MDEA Contactor, T-100)12

5.1.3. Valve (VLV-100)14

5.1.4. Flash Tank (V-101)14

5.1.5. Heat Exchanger (E-100)15

5.1.6. Mixer (MIX-100)16

5.1.7. Cooler (E-101)

5.1.8. Pump (P-100) 16

5.2. Acid Gas Removal17

5.2.1. Reflux-Reboiler Tower17

5.2.2. Cooler (E-102)18

5.2.3. Cooler (E-103)19

5.2.4. Component Splitter (X-100)19

6.   Equipment Specifications20

7.   Plant Safety Analysis22

7.1. Inventory Analysis23

8.   Economic Analysis29

9.   Conclusion & Recommendation(s)31

10. References32

Appendix A: Material Balance. 34

Appendix B: Equipment Sizing. 37

Appendix C: Material Stream Properties40

Appendix D: Stream Compositions41

Appendix E: Absorber Column Gradients42

Appendix F: Regenerator Column Gradients43