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Skrip

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skirp present
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  Assalamualaikum and good morning to the panel,….. Today I will present about my research project which entitled the optimization of LNG dehydration process. LNG is one of the type of natural gas where it is in liquid form when the methane gas is processed into LNG by cooling it to -161 o C. As the natural gas convert from gaseous state to liquid state, its volume decrease by a factor more than 600 times. Due to technical and economical reason, it is a favourable method to transport gas. Since natural gas is buried underground the formation, it contains impurities such as water. This water can form hydrates and cause corrosion in pipeline. So my project was done to accomplish 2 objectives which are first, to determine the most effective glycol as absorbent for absorption dehydration process and second, to evaluate the optimum parameters in absorption dehydration process. Next is my problem statement. Since natural gas is found deep in underground reservoir, it contains impurities such as water. This water can form hydrates when natural gas components such methane, ethane, h2s and co2 occupy the empty lattice positions in the water structure. This hydrates can block pipeline flow and control system. Therefore, dehydration process which is a process to remove water in natural gas is necessary. There are five scopes of research in this project. First, to design the simulation of gas dehydration plant by using Aspen HYSYS. Second, to investigate the type of glycols which are EG, DEG and TEG. Third, to study the effect of number of stages of an absorber in dehydration unit. Fourth, to study the effect of varying inlet gas temperature on glycol dehydration unit. And lastly, to investigate the effect of varying the reboiler temperature on glycol dehydration unit. For the methodology, this project is done by simulation by using Aspen HYSYS. First, I will design the natural gas plant. This is where I determine what kind of equipment need for dehydration unit. Second, I determine the condition and properties of natural gas plant. Here I specified the condition and composition and condition of natural gas stream and glycol stream such as temperature, pressure and flow rate. Then, I begin with the simulation by using the normal condition by using Aspen HYSYS. After that, I will varying the reboiler temperature, inlet gas temperature and change the number of stages of absorber. If all the equipment converged, then I will record and analyse the data. This is the process flow diagram of the gas dehydration plant. The results is analyse from these four graphs. From we can see, TEG glycol requires the smallest flow rate to achieve the lowest water content compared to EG and DEG. This is due to TEG can be regenerated more easily and has high boiling point and decomposition temperature. BP of TEG is 288 o C and BP of water is 100 o C. This huge difference make it easier to separate water from glycol. Plus, TEG has 2 OH bond which has strong affinity towards water molecule. Next is the graph of water content vs number of trays in absorber. We can see that the higher the number of trays, the lower the water content in dry gas. This is because when there are high number of trays, there are more contact areas between water and glycol. So this promotes absorption process. For the third graph which is water content vs inlet gas temperature, we can see that the lower the inlet gas temperature, the lower the water  content in the dry gas. When the inlet gas temperature is low, the gas velocity will decrease. So low diameter of vessel is required. So the cost can be reduce. For the last graph which is water content vs reboiler temperature, the higher the reboiler temperature, the lower the water content. This is because high temperature can vaporize more water vapour. For the conclusion, it can be concluded that the optimum condition of dehydration unit based on the results obtained are use TEG glycol, use 12 number of stages, 20 o C inlet gas temperature and 200 o C reboiler temperature. For the recommendation, the result need to be compared with the actual field data to be more accurate. Plus, in the future the simulation of others dehydration methods can be done to determine which method is most effective. *** Max water content  - 4 to 7 lb H2O/MMscf Inlet gas T <20 o C is not investigated due to raw gas T, composition and hydrate formation >50 o C cause high TEG losses. Reboiler T >200 o C is not simulated because TEG max regeneration temperature is 204 o C. glycol decomposition occur at 200 o C.
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