The influence of partial capture conditions on CO2 absorption in process industries

The amount of carbon dioxide in the atmosphere is increasing rapidly which leads to serious climate damage if nothing is done to address this situation. This thesis evaluates the application of carbon capture to process industries to reduce emissions and decrease the atmospheric carbon dioxide concentration. The main focus is on partial carbon capture where waste heat or heat surplus is used to run the capture process leading to a lower capture rate but simultaneously the costs are reduced since no additional heat supply is needed. The carbon capture processes are simulated using Aspen Plus where a standard set-up is first compared to an advanced split-flow configuration regarding the energy consumption. For both process designs a sensitivity analysis is conducted focusing on different parameters to optimize the carbon capture process. For comparison two different solvents, MEA and piperazine, are used for the sensitivity analysis of these two process configuration. The optimized process design of the split-flow configuration using MEA as a solvent is used to investigate different partial capture cases. These investigated cases are applied to an existing industrial case, a pulp mill. Two stacks of the pulp mill can be used to capture CO2 from, the recovery boiler and the lime kiln. In the recovery boiler steam is produced which is primary used to satisfy the need of the pulping process, but there is a heat surplus which can be used to produce electricity or to run the capture process. First it is investigated how much CO2 can be captured from the two stacks by using this heat surplus instead of producing electricity. The electricity loss per unit of CO2 captured was determined for different cases. The electricity loss is investigated for the case where CO2 is only captured from one of the two stacks and a case where CO2 is captured from both stacks always using only the steam available. . In cooperation with an external partner, cost estimations for different partial capture cases, applied to the pulp mill, are conducted. First full scale capture, where the capture rate is 90 %, was applied to both stacks. For the second case, the capture rate is decreased to 75 % having partial capture and the third case uses partial capture where the flue gas flow is decreased to 75 %. The two latter ones were only applied to the recovery boiler