Untersuchung chemischer Absorptionsverfahren auf Aminbasis zur CO₂-Abtrennung aus Rauchgasen

Anthropogenic climate change caused by emissions of greenhouse gases, in particular CO₂ from the use of fossil fuels, is one of the major global challenges of the 21^st century. In order to limit negative impacts of climate change on people and the environment, global warming should not exceed 1.5 °C relative to pre-industrial levels.

Fossil-fueled power plants are responsible for about 40 % of global CO₂ emissions. Various methods are currently being discussed and researched to reduce CO₂ emissions from power plants and combat climate change, including the substitution of fossil fuels, efficiency improvements and new combustion processes. One promising approach is the post-combustion CO₂ capture from flue gases. This involves using a chemical washing process with aqueous amine solutions, downstream of conventional flue gas cleaning, to separate CO₂. The amine groups absorb the CO₂ from the flue gas, which is then stripped out again by raising the temperature and using steam in a regeneration process, so the solution can be reused as an absorption solution. The advantages of this method include the ability to retrofit existing power plants and the provision of a pure CO₂ stream for increasingly discussed utilization.

In this work, the use of a spray scrubber on a pilot plant scale is investigated as a process engineering alternative to amine scrubbing with conventional packed columns. Spray scrubbers exhibit a lower pressure drop on the gas side and more flexible operation, but due to the lack of internals, the effective mass transfer surface is essentially limited to the spray.

The focus of this work is on the development and experimental testing of various possibilities to increase mass transfer in spray scrubbers for the separation of CO₂ with aqueous amine solutions. An aqueous 30 wt-% monoethanolamine (MEA) solution is used as the absorption solution. For this purpose, after an extensive investigation of the influence of the L/G-ratio and the specific heating power in the spray scrubber system, an internal absorbent recirculation within the absorber column as well as a tray insert are investigated. Finally, the additional influence of a bundle nozzle consisting of individual hollow cone nozzles is tested and the results are evaluated.