Cross-flow structured packing for the process intensification of post-combustion carbon dioxide capture

Gianluca Lavalle,Mathieu Lucquiaud,Marc Wehrli,Prashant Valluri

doi:10.1016/j.ces.2017.12.022

Gianluca Lavalle, Mathieu Lucquiaud + Show 2 more

Open Access

https://doi.org/10.1016/j.ces.2017.12.022

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Abstract

We introduce novel insights into a cross-flow arrangement of structured packings specifically for post-combustion carbon dioxide capture. Gas-liquid dynamics are investigated numerically, with the liquid flowing under the action of the gravity and the gas driven by a horizontal pressure gradient crossing the liquid phase. An elementary packing cell consists of two connected channels: one depicting a co-current gas-liquid flow and the other depicting a counter-current two-phase flow. While flow reversal of the liquid phase can occur in the counter-flow channel at high gas flow rates, the overall flooding point is significantly delayed in comparison to a counter-current flow arrangement traditionally used for structured packings. Varying the gas flow rate and the tilting angle of the elementary cell, a detailed numerical analysis of the flow repartition between channels, the pressure drop, the gas and liquid velocities, and the onset of flooding is presented. The pressure drop is found to be smaller when tilting the cell with respect to the initial scenario at 45°. Flow reversal instead is delayed when lowering the tilting angle, that is when the cell is tilted anti-clockwise. We also reveal the presence of long waves at the edge of the cell at low tilting angles. Finally, data of the wet pressure drop in the cross-flow cell are compared with different commercially available types of packing arranged in a conventional vertical counter-flow configuration, such as several versions of the Sulzer Mellapak™.

Highlights

Gas-liquid flows play a fundamental role in many chemical unit operations, such as the carbon dioxide absorption and distillation columns
In order to provide novel insights into the cross-flow arrangement, we present the first detailed Computational Fluid Dynamics (CFD) study of the gas-liquid flow within a three-dimensional elementary cell of such an alignment of structured packings, as shown in Fig. 1, where the gas flows parallel to the packing sheets
This article provides novel and fundamental insights into a disruptive concept for contacting gas-liquid flows, where a compact, cross-flow, horizontal structure is streamlined to match the typical exhaust gas pathway of modern thermal power stations for carbon capture processes. It presents the performance of the three-dimensional cross-flow elementary cell of structured packings, in particular for the process intensification of postcombustion carbon capture

Summary

Introduction

Gas-liquid flows play a fundamental role in many chemical unit operations, such as the carbon dioxide absorption and distillation columns. To enhance gas-liquid contact, common column internals used are structured packings. These optimised geometric structures, made of textured metal sheets to maximise interfacial contact area between a gas phase and a liquid phase, spread the. Liquid phase as a thin film to extend residence time and allow mass transfer and chemical reactions to complete. A gravity-driven falling liquid film flows downwards along the packing walls in the presence of an upward flowing gas at a constant pressure gradient (driven from the bottom of the column). A typical application being removal of CO2 from flue-gas using an amine solution in an absorption column

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