1. Simulation Of Gas Sweetening Process
CHEMCON- 2014
Simulation Of Gas Sweetening Process
V.Bharath, T.Ajeeth Prabhu, S.Padma,
Department of Chemical Engineering ,
Gayatri Vidya Parisad College of Engineering,
Visakhapatnam, India
M.Adity Kishore,
Senior Engineer-Project Execution-Chemical,
Brahmaputra Cracker and Polymer Limited (BCPL),
Assam, India

2. Contents Introduction Why sweetening should be done????
Gas sweetening process
Problem Statement
Selection of Process
Process description of Amine Absorption Process
Parameters involved in Sweetening process
Results and discussion
Conclusion
Simulation of Gas Sweetening Process- CHEMCON 2014

3. Introduction
Natural gas is a fossil fuel formed when the layers of buried plants , animals are exposed to intense heat and pressure over thousand of years .
Natural gas is a composition of Methane, Ethane, Propane, Butane, Nitrogen, CO2(Carbon Dioxide), H2S(Hydrogen Sulphide), some higher hydrocarbons and small amounts of Helium , water , impurities.
Generally Natural gas is of two types:
Acid Natural gas (containing significant amounts of H2S and Co2 )
Sweet Natural gas ( absence of H2S and Co2 )
Simulation of Gas Sweetening Process- CHEMCON 2014

4. Why sweetening should be done??????
The impurities present in the natural gas like H2S, CO2, Water , higher hydrocarbons and some other impurities leads to following problems:-
Corrosion problems
Transportation problem
Reduction of calorific value
Effects on the atmosphere
In order to avoid all these problems the Acid Natural gas Should be treated.
Simulation of Gas Sweetening Process- CHEMCON 2014

5. Problem Statement
This paper presents a simulation study of the impact of various process parameters, on the separation and removal of acid gases from natural gas stream.
The effect of the various parameters on the percentage removal of acid gas is studied.
The parameters are optimized to give the maximum percentage removal.
Simulation of Gas Sweetening Process- CHEMCON 2014

6. Gas Sweetening Process
Gas sweetening process refers to a group processes that used to remove the CO2 and H2S.
Gas sweetening process refers to an important purification process which is employed to remove the acidic contaminants from the natural gas prior to sale.
This gas sweetening can be employed using the different methods to remove the H2S and CO2 present in the natural gas.
PROCESS
SOUR GAS
ACID GASES
Simulation of Gas Sweetening Process- CHEMCON 2014

7. Techniques Employed In Gas Sweetening
Gas Sweetening Process
Chemical Absorption
Amine
Other Chemicals
Physical Methods
Physical solvents
Cryogenic
Fractionation
Membranes
Adsorption
Others
Hybrid
Direct Conversion
Simulation of Gas Sweetening Process- CHEMCON 2014

8. Criteria for selection of process
H2S and mercaptan concentration in the sour gas and sale gas C2O and total sulphur limits
Maximum design flow rate
Raw gas inlet pressure
Requirement of sulphur recovery
Acceptable methods of waste products disposal
Simulation of Gas Sweetening Process- CHEMCON 2014

9. Amine treating
The relative development of different Amines used in gas treating with the passage of time:
Monoethanolamine (MEA)
Diglycolamine (DGA)
Diethanolamine (DEA)
Methyldiethanolamine (MDEA)
Simulation of Gas Sweetening Process- CHEMCON 2014

10. Amine absorption process (Chemical Absorption)
Simulation of Gas Sweetening Process- CHEMCON 2014

11. Parameters involved in the process
Temperature
Pressure
Composition of natural gas
Lean amine concentration
Flow rate of feed stream
Number of trays in the absorber and stripper column
Tray efficiency
Type of amine used and
Cost , etc
Simulation of Gas Sweetening Process- CHEMCON 2014

12. HYSYS FLOWSHEET
Simulation of Gas Sweetening Process- CHEMCON 2014

13. Result and discussions
Pressure
% removal of CO2
% removal of H2S
950Psi
1000Psi
99.798
1250Psi
1500Psi
98.309
Temperature
% removal of CO2
% removal of H2S
80F
99.79
86F
90F
95F
98.029
Simulation of Gas Sweetening Process- CHEMCON 2014

14. Contd…… Flow rate % removal of CO2 % removal of H2S 15 MMSCFD 98.18766
20 MMSCFD
25 MMSCFD
30 MMSCFD
Weight fraction
% removal of CO2
% removal of H2S 22
98.965 25 28 30
Simulation of Gas Sweetening Process- CHEMCON 2014

15. Conclusion
The parameters are optimized using optimizer tool in ASPEN HYSYS to get maximum removal percentage of H2S and CO2and the optimized parameters are obtained as follows
Parameters
Optimized Values
Temperature
86F
Pressure
1000psi
Molar Flow Rate
25MMSCFD
Weight fraction
28% w/w
% Removal of CO2
% Removal of H2S
Simulation of Gas Sweetening Process- CHEMCON 2014

16. References
Dawodu O. F., Meisen A., 1996, Degradation of Alkanolamine Blends by Carbon Dioxide, The Canadian Journal of Chemical Engineering, Vol. 74,
Dr. A. H. Younger, P.Eng (April 2004), Natural Gas Processing and Technology, University of Calgary
John Polasek, Jerry A. Bullin, A technical paper on Selecting Amines for Sweetening Units, Bryan Research & Engineering, Inc.
Simulation of Gas Sweetening Process- CHEMCON 2014

17. Simulation of Gas Sweetening Process- CHEMCON 2014