| dc.description.abstract | The growing concern over CO2 emissions has led to the development of CO2 capture technologies, with amine absorption, especially using monoethanolamine (MEA), being a widely adopted method for removing CO2 from industrial gas streams.
This study aims to advance the automation of cost optimization for CO2 capture via amine absorption, specifically using Aspen HYSYS models. The project focuses on simulating the CO2 capture process, dimensioning equipment, and automating cost estimation using the Aspen In-Plant Cost Estimator and the Enhanced Detailed Factor (EDF) method. The primary goal is to create a robust and automated process that optimizes CO2 capture costs, considering both capital expenditure (CAPEX) and operational expenditure (OPEX).
The study utilizes flue gas data from a natural gas-based power plant at Mongstad, Norway, to develop and simulate a process design in Aspen HYSYS. The base case scenario involves an absorber packing height of 15 meters, a desorber packing height of 4 meters, an 85% CO2 removal efficiency, and a minimal temperature difference (ΔTmin) of 8°C in the lean/rich amine heat exchanger. For the base case, the overall cost was calculated at 44 EUR/ton of CO2 captured, with an energy consumption of 4126 kJ/kg CO2 in the reboiler.
Several case studies were conducted to identify cost-optimal scenarios. The first case study focused on optimizing the economic performance of the lean/rich amine heat exchanger by adjusting ΔTmin from 8 to 18°C. The optimal ΔTmin was found to be around 15°C, with a CO2 capture cost of 42.5 EUR/ton and a reboiler duty of 4216 kJ/kg. This case study highlighted the trade-off between heat exchanger size and steam consumption, with automated calculations suggesting an optimal ΔTmin between 14 and 16°C.
The second case study examined the absorber packing height, varying it from 13 to 18 meters. The optimal packing height was determined to be 14 meters, resulting in a CO2 capture cost of 43.9 EUR/ton and a reboiler duty of 4036 kJ/kg CO2. This study revealed that increasing the number of absorber stages reduces the amine circulation rate and reboiler duty, influencing both capital and operational costs. It also suggested that higher CO2 concentrations in flue gas could lower costs, warranting further research into this variable.
The third case study explored the impact of varying inlet gas velocity to the absorber, ranging from 1.5 to 3 m/s. The most cost-effective velocity was found to be 2.5 m/s, with a CO2 capture cost of 53 EUR/ton and a minimum reboiler duty of 4183 kJ/kg CO2. Higher velocities initially reduced costs by enhancing CO2 absorption efficiency, but beyond 2.5 m/s, costs increased due to decreased contact time between the flue gas and amine solvent. | |
