The process intensification of CO2 absorption in Hilbert fractal reactor fabricated by a 3D printer

Abstract

CO2, as a major greenhouse gas, contributes greatly to the global warming. Increasing the efficiency of CO2 capture and utilization has becomea worldwide challenge. In the present research, Hilbert fractal reactor was fabricated via 3D printing technology for process intensification of ethanolamine (MEA) CO2 absorption. The performance of the Hilbert fractal reactor was investigated and compared to the serpentine reactor. For constant gas and liquid flow rates, the CO2 removal efficiency, the absorption rate, and the assumption of MEA increased with increasing concentration of MEA. In the comparison with the serpentine reactor, the CO2 removal efficiency in Hilbert fractal reactor is higher than that in the serpentine reactor at the relative low gas flow rate. The continuous bending in the Hilbert fractal reactor enhances the shear stress of the fluids, and the gas phase is segregated into the small bubbles which significantly increase the interface mass transfer. Under the relative high gas flow rate, the residence time of CO2 is short and the flow pattern in Hilbert reactor turns into the annular flow which adverse to CO2 absorption rate, and the advantage of Hilbert fractal reactor over serpentine reactor becomes negligible. The maximum CO2 removal efficiency of 57% was obtained in Hilbert fractal reactor.