Ultrasound assisted desorption of CO2 from MEA solution in the presence of VRAs

Monoethanolamine (MEA) is the most used solvent compared to other amines for CO2 capture in the post-combustion processes [1]. However, disadvantages like the requirement of high energy for desorption [4], reduction in CO2 carrying capacity of the solvent [2], and thermal degradation of MEA at the stripper operating conditions [3] are major causes of concern for large scale post-combustion CO2 capture plants.These drawbacks can be countered by intensifying the capture process.

Use of ultrasound to assist the stripping of the solvents by heat can significantly unlock cost savings in CO2 capture plants [5]. Ultrasound results in cavitation in liquids leading to the formation of bubbles which grow by further diffusion of gas into them, thus providing an easier way for the gas to escape in the form of bubbles [6].The aim was to determine the rate and amount of CO2 desorbed from loaded MEA solventsand the impact of various parameters like the concentration of MEA, intensity of ultrasonic power, temperature, and loading of the solvent.

In addition, innovative additives developed at DTU known as the Vapor Reduction Additives (VRAs) have also been tested at different concentrations. VRAs have the capacity to reduce the vapour pressure of water and similar solvents including amines, which reduces the amount of water evaporated and thus the energy required in the condenser and reboiler sections.

Use of ultrasound in addition to the VRAs can significantly reduce the size of the equipment in addition to the reduction in operational costs.