Work

CO2 absorption in pilot-scale multi-nozzle spray towers: CFD and experimental study of flow and mass transfer dynamics

Year: 2025

Type: article

Abstract: This study presents a comprehensive investigation into CO 2 absorption in a pilot-scale, multi-nozzle spray tower operating under industrial conditions. Through the integration of pilot-scale experimentation and reactive CFD modeling, this work advances the quantitative understanding of coupled hydrodynamic behavior and mass transfer phenomena in conditions representative of full-scale operations. A modular carbon capture unit was built and deployed at a Swedish waste-to-energy facility to experimentally investigate gas–liquid flow behavior and CO 2 absorption performance using a 15 wt% NaOH solution as the absorbent. The experimental data provided the basis for validating a reactive Euler–Lagrange multiphase CFD model, which elucidated gas–liquid interactions, including droplet dispersion, turbulent flow structures, mixing, and interphase mass transfer. Sensitivity analyses across a range of gas (50–200 m 3 /h) and liquid flow rates demonstrate how operating conditions influence droplet trajectories, residence time, and CO 2 absorption efficiency. Flow segmentation identifies two distinct zones where turbulence and recirculation enhance mixing and mass transfer, with side gas inlet configurations providing more effective radial mixing compared to axial inlet designs. Results demonstrate that tuning the liquid-to-gas (L/G) ratio, droplet characteristics, and gas inlet design significantly influences CO 2 capture, offering practical guidance for the next generation of spray-based carbon capture systems. The study investigated L/G ratios ranging from 2.3 to 7.0 kg/kg and examined the effects of droplet sizes between 200 and 3000 μm, observing that droplets predominantly in the lower size range exhibited improved dispersion and extended residence times, which are favorable for effective CO 2 absorption. The findings provide a direct basis for optimizing hydrodynamics and scaling spray tower absorbers for effective CO 2 capture in real-world systems.

Source: Results in Engineering

DOI: 10.1016/j.rineng.2025.106746

Authors: Ali Najarnezhadmashhadi, Sajad Jafari, Carl Häggmark, Henrik Kusar, Christophe Duwig

Institution: KTH Royal Institute of Technology

Language: English

Topic: Carbon Dioxide Capture Technologies

Subfield: Mechanical Engineering

Field: Engineering

Domain: Physical Sciences

SDGs: Climate action, Affordable and clean energy

Open Access status: gold

Estimated APC paid: $1,940