Performance of novel carbonate-based CO2 post-combustion capture process

A novel carbonate-based CO₂ capture process was developed at VTT, and proof-of-concept was tested using a bench scale device. The process has closed-loop, carbonate liquid, and the captured CO₂ is released at under-pressure. The temperature is around 65 °C, which enables, for example, utilisation of waste heat streams in process integrations. The process performance and its parameters were tested using 8 w-% sodium carbonate liquid with simulated gases, real flue gases and biogas. Also, the absorption mass transfer kinetics and suitable flow parameters of the invented microbubble generator were assessed. The device has successfully and continuously run for tens of hours, and the typical CO₂ capture rate between 72 and 84 % were performed at the liquid pH value of 9.3, using a near-atmospheric pressure process. Mass transfer rates k_La for carbonate liquid and air were between 0.14 and 0.34 s⁻¹, which indicates efficient gas absorption, enabling size reduction of the device size.