جستجوی مقالات مرتبط با کلیدواژه « natural gas sweetening » در نشریات گروه « فنی و مهندسی »

The natural gas sweetening unit usually involves an absorption column and a distillation column. The absorption column completely removes H2S and CO2 from natural gas, and the distillation column is used to recover the solvent. The main problem is high energy consumption in the gas sweetening process, particularly in the distillation column, necessitating energy optimization of this process. A novel method was used in this study for heat integration of the natural gas sweetening process. To this end, liquid and vapor streams leaving the absorption column entered the top and bottom of the distillation column, respectively. The feed entering the distillation column was preheated by the bottom product. The liquid and vapor streams reduced the cold and hot utilities of the distillation column, and feed preheating reduced the heat duty of the reboiler. The recycled solvent was then pre-cooled by the sweetened gas. According to the results, the proposed method reduced energy consumption by 67%. Moreover, the proposed process could reduce the total annual cost (TAC) of the base process to the maximum value of 66.7%. This reduction in TAC is due to the reduction of operating cost and capital cost by 66.77 and 66.64%, respectively.

The sweetening unit of the Ilam Gas Refinery plays a major role in providing olefin feed, and at the present time, the provinces of Ilam, Kermanshah, Hamedan, Kurdistan, and Lorestan in Iran are the consumers of the gas produced by this refinery. The gas sweetening unit of the Ilam Gas Refinery has an absorption and distillation column. H2S and CO2 are removed by diethanolamine in the absorption column, and the entrainer is recovered in the distillation column. The concern is the high energy consumption of this process, particularly the distillation column. In this study, a novel method for heat integration of the distillation column of the gas sweetening unit of the Ilam Gas Refinery was used, so that the feed entering the distillation column was splitted into two sections prior to feeding. Afterwards, the bottom section was preheated by the bottom product of column. Preheating the bottom section of feed decreased the reboiler and condenser duties. The results demonstrate that the proposed method decreases the energy consumption by 17%.

Natural gas usually contains significant amounts of acid gases when it is extracted from underground reservoirs. Therefore, it must be treated by appropriate processes to remove these acidic components. In this study, the simultaneous absorption of carbon dioxide and hydrogen sulfide from natural gas into diethanol amine solution was simulated using CFD. Absorption process was performed in a wetted-wall column with counter-current gas-liquid flow. A two-dimensional simulation based on the volume of fluid model was used. To investigate the hydrodynamics of the flow in the column, distribution of the volume fraction of phases along the column, the formation of liquid film and velocity profiles were studied. To validate the results for predicting the liquid film thickness, the column was simulated at different flow rates of water and air in laminar flow regime. Simulation results for liquid film thickness were compared with experimental data. Then by considering the mass transfer from the gas phase to liquid phase based on Higbie’s penetration theory, the concentration distribution of components in gas and liquid phases was calculated. The effect of temperature on absorption of and was also studied. The comparison of simulation results with the experimental data for the outlet concentrations in the gas phase showed that there was a good agreement between them. The developed model can also be used in further studies to determine the effective parameters on simultaneous absorption of and in a wetted-wall column. This helps to optimize the performance of the sweetening process in gas refineries.

This study evaluates the effect of Structural modifications on energy consumption of gas treatment units of BIDBOLAND refinery (Iran’s first gas refinery). To this aim, Aspen HYSYS (V.8.3) software was employed for the unit simulation in rate based method. The results show that as CO2 content in inlet sour gas is less than 2 percent and MDEA solution is used as solvent, using multiple feeds to the absorption column, static mixers and absorption column sidestream cannot reduce energy consumption level; while using desorption column sidestream and a flash unit can reduce the unit energy consumption up to 10 percent.

This investigation attempts to evaluate and compare the effect of packing type on the mass transfer and pressure drop along the gas sweetening absorption column. To this aim, modern packings such as Super Ring, Ralu Ring, Ralu Flow and the second-generation packing (Pall Ring), have been used in simulated columns by using of Aspen HYSYS modeling software. Flooding calculation is made possible by linking Aspen HYSYS with MATLAB programing. The selected models validity is checked by comparison to empirical data from a real gas plant. It should be noted that empirical data is available just for second-generation packing. Comparison of these packings performance shows that Super Rings provide low pressure drop, Ralu Rings lead to high mass transfer and Ralu Flow packings can provide high mass transfer and low pressure drop in absorption columns. According to results, the capacity of gas treatment units can be significantly increased by replacing Pall Ring with Ralu Flow.