SIMULATION AND OPTIMIZATION OF A NATURAL GAS DEHYDRATION SYSTEM WITH TRIETHYLENE GLYCOL.pptx

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1. SIMULATION AND OPTIMIZATION OF A NATURAL GAS DEHYDRATION SYSTEM WITH TRIETHYLENE GLYCOL

2. OUTLINE Background of Study Statement of the Problem Aim and Objectives of the Study Significance of the Study Scope and Limitation of the Study Literature Review Materials and Method Results and Discussion Conclusion and Recommendations

3. BACKGROUND OF STUDY Natural gas are fossil fuel produced from underground reservoir that contains huge amount of light hydrocarbon mainly methane together with ethane, propane and butane. This fuel is the most efficient fossil fuel, offering much benefit when compared to using the coal and oil due to its low carbon emission.

4. STATEMENT OF THE PROBLEM Raw natural gas from the production wells contains many impurities such as: Hydrogen Sulphide , Carbon dioxide, Nitrogen, inert gases, metallic compounds, water etc. These impurities must be properly removed and One of such treatment is to remove the water content which is often present in the form of water vapour , and if not properly removed may cause serious problems such as corrosion of the gas pipelines, catalyst deactivation, gas hydrate formation, side reaction and burn less.

5. AIM AND OBJECTIVES OF THE STUDY The aim of the study is to effectively remove the water content of raw natural gas using Triethylene Glycol as the absorbent. OBJECTIVES Simulate Natural gas Dehydration process using Aspen HYSYS using available industry data. Investigate the effect of operating parameters on the efficiency of the process. Optimize the Triethylene (TEG) regeneration process using Design Expert.

6. SIGNIFICANCE OF THE STUDY This study uses TEG to dehydrate natural gas, as glycol liquid has high affinity toward water vapor. Dehydrated gas (sales gas), serves several purposes such as generation of electricity using gas turbine, domestic cooking gas, heating as it is more effective than electric heating pumps, it is also use in the industry as raw materials for the production of other chemicals.

7. SCOPE AND LIMITATION OF THE STUDY This study focuses on the simulation and optimization of the natural gas dehydration plant using Aspen HYSYS and Design-Expert software respectively to investigate the effectiveness of TEG in the dehydration of wet natural gas and to analyze the optimum parameters which yield maximum Recycled TEG. TEG is known to decompose at temperature of 206 C which is far lower than its boiling point of 285 C and this limits the temperature of the TEG regenerator reboiler.

8. LITERATURE REVIEW AUTHOR WORK FINDINGS Siti et al., (2012) Investigate the effect of different types of glycol in terms of their ability in dehydrating the wet natural gas to give the most minimum water contents in the dry gas were studied. He observed from the studies that triethylene glycol gives a better absorption rate of water from the wet gas when compared to ethylene and diethylene glycol. Neagu et al., (2017) Investigated the technical and economic evaluations of the TEG regeneration processes by evaluating various stripping gas flowrates to improve TEG purity. Their work result indicated that the stripping gas configuration is a more effective way of improving the TEG purity and regeneration performance. Affandy et al., (2017) Investigated the optimization of the TEG unit by replacing the TEG Contactor internals from tray to structured packing Their results shows that packed bed column can reduce the size of the column and also reduced the total annual cost of the natural gas dehydration unit. Kong et al., (2018) developed a framework to carry out a techno-economic comparison between the conventional and stripping gas dehydration process. They concluded that using inert gas such as N 2 reduces the partial pressure of the water vapor in the TEG regenerator column thus reducing the mole fraction of water in TEG solution. Chebbi et al., (2019) Investigated the impact of several operating parameters such as pressure, temperature, TEG circulation rate, and stripping gas flow rate to capital and operating cost They presented their main conclusions based on parametric optimization analysis that lower dehydration cost can be achieved at higher pressure, lower temperature and at higher TEG concentration without stripping gas.

9. MATERIALS AND METHOD Materials/Equipment Method Aspen HYSYS was used to simulate the Dehydration Process Design-Expert software was used for the Optimization Process Fresh TEG Wet Gas Contactor (Absorber) Regeneration (Distillation column) Pump Heat Exchanger TEG Mixer, etc.

10. RESULTS AND DISCUSSION Summary of Simulation Results Component Fresh TEG Wet Gas Sales Gas Recycled TEG Methane 0.0000 0.8565 0.9406 0.0000 Ethane 0.0000 0.0614 0.0401 0.0001 Propane 0.0000 0.0494 0.0152 0.0002 i-Butane 0.0000 0.0100 0.0003 0.0003 n-Butane 0.0000 0.0095 0.0033 0.0000 i-Pentane 0.0000 0.0083 0.0003 0.0005 n-Pentane 0.0000 0.0040 0.0002 0.0000 H2O 0.1021 0.0010 0.0000 0.0030 CO2 0.0000 0.0000 0.0000 0.0000 H2S 0.0000 0.0000 0.0000 0.0000 Nitrogen 0.0000 0.0000 0.0000 0.0000 TEGlycol 0.8979 0.0000 0.0000 0.9959 Total 1.0000 1.0000 1.0000 1.0000

11. RESULTS AND DISCUSSION Graphical representation of the effect of temperature on Recycled TEG Graphical representation of the effect of pressure on Recycled TEG Optimization Results

12. RESULTS AND DISCUSSION 3D Plot showing the effect of temperature and pressure on recycled TEG response. Graphical representation of the effect of flow rate on Recycled TEG Optimization Results

13. Discussion of Results RESULTS AND DISCUSSION From the optimization result, the optimum operating temperature, pressure and flow rates for the process were found to be 25 o C, 6320kpa and 1883kgmole/h respectively, this process variable values gives an optimum yield of Recycled TEG of 99.89mol% of the Recycled TEG stream.

14. CONCLUSION AND RECOMMENDATION Based on the results obtained, it can be concluded that: The column pressure of the absorption column should be minimized to reduce the amount of hydrocarbons trapped in the wet TEG stream leaving the bottom of the absorber, a minimum possible number of trays should be used in the regeneration to minimize operating cost. For Optimum operation, the simulation should be carried out at a temperature of 25 o C, pressure of 6320kpa and a flow rate of 1883kgmole/h, so as to yield maximum recycled TEG. Based on the findings of this work, it is recommended that the TEG regenerator reboiler temperature should not exceed 206 C as thermal degradation of TEG occurs at this temperature which is far less than its boiling point of 285 C.