CO2 capture and sequestration from a mixture of direct air and industrial exhaust gases using MDEA/PZ: Optimal design by process integration with organic rankine cycle

Abstract

Achieving climate change targets requires a massive reduction in carbon dioxide emissions. According to the Paris agreement, this amount should be reached to 30 Gt/year CO2 reduction. Among different energy and environmental technologies, CO2 Capture and Storage (CCS) technologies are promising technologies to achieve those goals. Despite different technical, economical, and environmental CCS challenges, process development based on recent advances can significantly facilitate the CCS’s deployment. This study aims to simulate the absorption system of CO2 with Methyl-Diethanolamine (MDEA) and Piperazine (PZ) absorbents. In this study, three different scenarios have been considered for designing the parts of the absorption tower and air blower that have the highest energy consumption to achieve the highest amount of absorption, purity, and CO2 recovery. Compared results from the defined scenarios show that the use of an intercooler in the middle of the adsorption tower (Scenario 3) is the best design for the CO2 capture simulated process where the adsorption rate is 90.1%, the purity is 82.26 (mol%) and CO2 Recovered reaches 28.74 ton/hr. Since energy consumption in high CO2 absorption rate and purity is one of the main challenges of such technologies, this study also evaluates the combination of the organic Rankin cycle (ORC) with air blowers by three refrigerants R290, R227, and R124 to reduce energy in the carbon capture units. The results show that in this cycle, R290 has the highest power output against R227 and R124 refrigerants under the same conditions. Combining ORC with an air blower reduces the cooling load of the whole process to 104.85 MW and the total power consumption to 46.375 MW. Finally, this study concludes that using different designs and combinations, including ORC cycles in high-energy CCS processes, can also reduce the cost of energy required, and its deployment can help prevent climate change.