Utilization of aspen hysys simulation to determine the optimum absorber working pressure needed to achieve more than 0.99 methane purity from egyptian biogas

Egypt has many sources that can be utilized in renewable energy generation, for example, agricultural waste, sewage waste and livestock production, which can be utilized in biogas generation. Biogas is not only one of the promising renewable energy sources in Egypt, but also it can be used in Industrial and research purposes. However, using biogas in industrial and research purposes needs to use an advanced technique for purification and enrichment in order to achieve high methane purity more than 99%.Whatever the purpose of biogasapplication, it is essential to clean it from acidic gases before using it.Biogas contains mainly two acidic gases they are CO2 and H2S, whichmust be minimizedin biogas total composition before pumping it in natural gas pipelines in order to insure the compatibility between biogas composition and natural gas network quality standards. In case of using biogas in industrial and research purposes such as X-ray metal analyzer the biogas CO2 and H2S contents must be equal to zero in order to achieve methane purity 99 % or more. This article aims to upgrade the Egyptian biogas to achieve 99 % methane purity by removing the acidic gases CO2 and H2S completely from Egyptian biogas composition. In order to make a proper design of biogas acidic gascleaning plant, Aspen HYSYS software can be used as one of numerical simulation programs.Using the typical acidic gas treating plant which plugged in Aspen HYSYS 8.6 library, and used for natural gas treating, it is possible to simulate the biogas treating process, but after taking in consideration the differences between partial pressures of CO2 and H2S in both of natural gas and biogas. This Partial pressure difference leads to study the relation between inside treating gas treating cycle main equipment, and both of CO2, H2S and methane volume contents of the final sweetening gas product.After drawing relation curves it is easy to determine the optimum working pressure, whichcan be used to achieve methane purity more than 99 % from Egyptian biogas. The natural gas treating process was done inside Pressure Swing Absorber (PSA) where the feed sour gas enters the absorber atthe CO2 contents of 0.025,H2S contents of 0.007, a temperature of 37 C, a pressure of 30 bars, a flow rate of 13 m3/hour,Diethanolamine (DEA) concentration of 0.3 and 20 stages PSA has atray diameter of 1.7 m.Then the final methane purity can be obtained from natural gas is 96 %.Using the same cycle with the same conditions, but after the regulation of the PSA working pressure to be suitable for Egyptian biogas treating, a 20 bar PSA working pressure will be obtained as the optimum pressure needed to achieve 99 % methane purity from Egyptian biogas.

Sameh Tawfik Abd Elfattah, Yehia A. Eldrainy and Abdelhamid Attia
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Int J Inf Res Rev
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