Post combustion CO2 capture by reactive absorption: Pilot plant description and results of systematic studies with MEA

Reactive absorption is one of the most promising technologies for post combustion CO2 capture (PCC). There is a need for methods and equipment that allow studying PCC efficiently on scales that are many orders of magnitude smaller than those of future installations in power plants. The present work describes in detail the set-up and operation of a pilot plant that is suited for that purpose. In that pilot plant the closed cycle of the absorption/desorption process is continuously operated (column diameters: 0.125 m, absorber/desorber packing height: 4.2/2.5 m, packing type: Sulzer Mellapak 250.Y™, flue gas flow rate: 30–110 kg/h, CO2 partial pressure: 35–135 mbar, solvent flow rate: 50–350 kg/h). The plant is equipped with high-end measuring instrumentation and is operated using an automated process control system. Sampling points allow the determination of the liquid phase concentration profiles in both columns. Two reference experiments that were carried out with an aqueous solution of 0.3 g/g monoethanolamine (MEA) are discussed in detail. The results give insight in the process behaviour in general and in the way such plants should be operated and how the evaluation of the results should be carried out. Based on comprehensive experimental studies with aqueous MEA solutions the influence of all important process parameters like CO2 partial pressure, CO2 removal rate, fluid dynamic load of the absorber, solvent flow rate, desorber pressure and solvent composition on the process behaviour is discussed in detail. These results allow a comprehensive understanding of the absorption/desorption process, which is important not only for the development of new tailor-made solvents but also for the design and operation of large scale plants. Furthermore the data establish a base line for comparisons with new solvents tested in the pilot plant and can be used for a validation of models of the PCC process with MEA.