The Modeling and Sizing of the Purification Train Required for the Removal of Carbon Dioxide from Synthesis Gas Solution Using Aspen Plus

A common method for the mass production of synthesis gas involves the partial oxidation of methane using an alkanolamine solvent for the purification process. Synthesis gas is not only a clean-burning fuel itself, it is also used to generate electricity, produce gasoline and diesel fuel.  Other functions of synthesis gas include the production of chemicals such as methanol and ammonia. A drawback for producing synthesis gas via a partial oxidation reaction is the impurities produced when the reaction takes place. That is, a small amount of carbon dioxide is produced. The purpose of this study is to use the computer-aided technology Aspen Plus, to accurately model the towers required to remove carbon dioxide from our product in the most efficient way. The composition of the flue gas contains 2.75 mole % of CO₂. After the towers are modeled, they will be sized using flooding correlations, such as Fair’s and Kister and Haas correlations. A program called SULCOL from Sulzer Chemtech will also be used to size the towers. Preliminary results have shown that we need two towers for the efficient removal of carbon dioxide. One uses 30 % by wt. diethanolamine to remove the carbon dioxide from the product and the other separates the carbon dioxide from the diethanolamine so the solvent can be recycled back into the first tower. Understanding the process for the production of synthesis gas is not only important for students in the field of chemical engineering, but also for the mass producers of synthesis gas.