Raman-based Advanced Control of an Absorption Desorption System

For absorption processes with fluctuating feed gas compositions it is vital to continuously adjust the operation point to achieve energy efficiency. In this contribution a Raman-based advanced process control (APC) is introduced for the absorption of carbon dioxide (CO2) using an aqueous solution of monoethanolamine (MEA). The APC is based on a Raman spectroscopic analysis of the composition and CO2 load of the scrubbing liquid and a non-linear model predictive control (NMPC) to adjust the scrubbing liquid cycle. In addition, an outer real-time optimization loop is set in place to update the set points for the absorption process depending on the current feed gas composition minimizing the energy consumption of the process. Implementation and testing of the APC have been carried out in a mini-plant at TU Berlin. During a plant operation of more than 160 hours robustness and stability of the APC were shown.