Session: 10-06-02: Fluid Measurements and Instrumentation

Paper Number: 145922

145922 - An Experimental Study on the Evaporation Characteristics of Free-Suspended Droplet of Monoethanolamine Solutions 

The emission of carbon dioxide (CO2) from various industrial processes, such as the combustion of fossil fuels, has attracted much attention in the past decades. Post-combustion carbon entering the atmosphere is one of the main causes of global warming. Different technologies have been developed to capture carbon from gases containing carbon, to mitigate carbon emissions during industrial applications. Solvent-based carbon capture is one of the most important options and advanced technologies for decarbonization, which comes with the advantages of high stability, capacity, and technology readiness level.

Monoethanolamine (MEA) is the most used solvent in solvent-based carbon capture processes because of its excellent performance, even with low CO2 concentration flue gas. Conventionally, MEA-based CO2 capture was to inject MEA solution from the top of an absorber filled with fuel gas for CO2 absorption. During the absorption of CO2 in MEA, a series of chemical-based processes occur, including the formation of carbamate, the hydration of CO2, and the hydrolysis of carbamate. After the reaction process, the CO2-rich MEA solution was drained from the bottom of the absorber for the following CO2 recycling process.

During the CO2 capture process, however, evaporation of the MEA solution would also take place, which can degrade the CO2 capture efficiency. Thus, it is desirable to evaluate the evaporation dynamics of MEA solutions to inform the future development of MEA-based CO2 capture technologies.

In this paper, we developed an experimental platform to study the evolution of one single MEA solution droplet suspended in air. MEA solution droplets with different concentrations were suspended in the air using an acoustic levitator. As time went on, a chemical reaction between MEA and air and the evaporation of the MEA solution droplet occurred. A high-speed camera was used for recording, and the captured images of droplets were analyzed using image processing methods to obtain the diameter of the MEA solution droplet.

According to experimental results, the diameter of suspended droplets decreased over time because of evaporation. In addition, two rates of diameter decrease were identified during droplet evaporation, which corresponds to a fast evaporation at the beginning and a slow evaporation at the latter stage of the same droplet. Since the evaporation rates of water and MEA were different, it suggested that the evaporation of water was faster than MEA in the droplet. Thus, the concentration of suspended MEA solution droplets was increased over time with a significant loss of water. Since water plays an important role during the chemical reaction process, the evaporation of water may provide undesired effects on the performance of MEA-based CO2 capture.

Based on the results obtained from this research, a new insight has been experimentally proved that the concentration of MEA solution droplet was not constant due to water loss during evaporation. It provided an important reference for developing a spray nozzle with advanced performance in MEA-based CO2 capture technology.

Presenting Author: Haipeng Zhang City College of New York

Presenting Author Biography: Dr. Haipeng Zhang is currently a Postdoctoral Research Associate in the Department of Mechanical Engineering at the City College of New York. He received his Ph.D. degree and M.S. degree in Mechanical & Materials Engineering from the University of Nebraska‐Lincoln in 2022 and in 2018, respectively, and his B.S. degree in Mechanical Engineering from the Kitami Institute of Technology, Japan in 2007. He also worked for the pump department at the Beijing Office (China) of the KUBOTA Corporation between 2009 to 2015.

Authors:

Haipeng Zhang City College of New York
Tad Misztal City College of New York
Yang Liu The City College of New York