Optimum conditions and maximum capacity at the amine-based CO2 capture plant at TCM Mongstad
Abstract
Using amine-based solutions is a mature method for CO2 capture. The study simulates this process for Technology Centre Mongstad (TCM) using a rate-based model in Aspen Plus. The main purpose is to develop a rigorous model for TCM and find the operation limits, maximum utilization capacity, and maximum achievable CO2 removal efficiency at the plant.
The model accuracy is verified by using different scenarios from the test campaign reports at TCM with four main configurations: Combined Heat and Power (CHP) flue gas, Refinery Residue Fluid Catalytic Cracker (RFCC) flue gas, lean vapour compression, and cold rich-solvent bypass. The deviation between the experimental data and simulation results is compared. The model shows more accuracy with more detailed input data and accurate practical parameters.
The verified model is used with scenario MHP with all the TCM configurations to simulate the plant. Aspen EDR is also used to design real heat exchangers. To avoid flooding, the maximum gas flow to the direct-contact cooler and absorber column is 78500 and 52000 Sm3/hr respectively. There is a maximum reboiler duty of 8.4 and 3.4 MW for RFCC and CHP stripper at the plant respectively. The optimum operating condition to achieve a CO2 removal efficiency of 90% after amine lean loading adjustment by using maximum gas flow, both strippers, and 15% of rich-solvent bypass gives a total SRD of 3.0 MJ/kgCO2.
By using a maximum amine flow rate of 230 ton/hr, a CO2 removal efficiency of 98% can be achieved. The optimum modification gives a bypass fraction of 19% and SRD of 3.63 MJ/kgCO2. Moreover, sending the condensed water to the CHP stripper will give an SRD of 3.65 MJ/kgCO2, which is less energy efficient than the previous configuration.