Refineries produce about four percent of the global carbon dioxide emissions, close to one billion tons per year. Globally, the refining sector is the third largest producer of carbon dioxide after the electricity generation and cement industry.This greenhouse gases is a major cause of global warming and climate change and is a serious threat to human health and the environment. One way to reduce this greenhouse gas into the atmosphere is to reduce carbon dioxide by reversing this gas in the fuel cycle.The Fluid Catalytic Cracking unit (FCCU) is one of the emissions sources of this greenhouse gas in Abadan Refinery,which produces 230 tons per hour of combustion gases,it has 12.7% mole of carbon dioxide. Identifying the sources of carbon dioxide emissions in Abadan Refinery and simulating the chemical absorption of this greenhouse gas and converting it into methanol fuel is one of the objectives of this study.
 Methods: In this research, the concentration of carbon dioxide emitted from the emission sources of Abadan Refinery has been measured by Testo 350-XL and GC. Due to the fact that the concentration of carbon dioxide in the combustion gases of the FCC unit was the highest amount, so the chemical absorption of carbon dioxide from the combustion gases of this unit by 30 wt% diethanolamine solvent and converted into methanol during a hydrogenation reaction has been simulated with Aspen Hysys software. Finally, the economic calculations of the project were performed.
Results: The overall efficiency of chemical absorption of CO2 in the simulation with software is 92% and the purity of captured CO2 is 94.6%. With this method, 1003 ton per day of carbon dioxide in FCC unit can be absorbed and recovered and also converted into methanol product. In the simulation of the conversion of recovered carbon dioxide into methanol, the amount of 686 ton per day of methanol with a purity of 99.8% was obtained. The economic calculations of the project show that the cost of reducing emissions per ton of carbon dioxide is $ 19. The internal rate of return on the project is 22% and the net present value of the project is $ 92 million. The return time on investment of this project is 3 years.
Conclusion: Diethanolamine has a high efficiency in absorbing carbon dioxide from combustion gases.By chemical absorption method with this amine, carbon dioxide pollutant can be recovered from combustion gases that produced in refineries and used as an inexpensive feed to produce methanol fuel.This method, in addition to creating added value, prevented the emission of this greenhouse gas into the environment.