The Department of Energy’s Oak Ridge National Laboratory (ORNL) researchers have developed a first-of-its-kind aluminium device that enhances the capture of CO2 emitted from fossil fuel plants and other industrial processes.
ORNL’s device focuses on a key challenge in conventional adsorption of carbon using solvents. By using additive manufacturing, the researchers were able to custom design a multifunctional device that improves the process efficiency by removing excess heat.
Adsorption, one of the most commonly used and economical methods for capturing CO2, places a flue-gas stream from smokestacks in contact with a solvent, such as monoethanolamine, known as MEA, or other amine solutions, that can react with the gas.
The team tested the novel circular device, which integrates a heat exchanger with a mass-exchanging contactor, inside a one-meter-tall by eight-inch-wide adsorption column consisting of seven commercial stainless-steel packing elements. The 3D-prinited intensified device was installed in the top half of the column between the packing elements.
Additive manufacturing made it possible to have a heat exchanger within the column, as part of the packing elements, without disturbing the geometry, therefore, maximising the contact surface area between the gas and liquid streams.
“We call the device intensified because it enables enhances mass transfer through in-situ cooling. Controlling the temperature of adsorption is critical to capturing CO2,” said Costas Tsouris, one of ORNL’s lead researchers on the project.
When CO2 interacts with the solvent, it produces heat that can dimmish the capability of the solvent to react with CO2. Reducing this localised temperature spike in the column through cooling channels helps increase the efficiency of CO2 capture.
“Prior to the design of our 3D printed device, it was difficult to implement a heat exchanger concept into the CO2 absorption column because of the complex geometry of the column’s packing elements. With 3D printing, the mass exchanger and heat exchanger can co-exist within a single multifunctional, intensified device,” said ORNL’s Xin Sun, the project’s Principal Investigator.
Embedded coolant channels were added inside the packing element’s corrugated sheets to allow for heat exchange capabilities. The final prototype measured 20.3cm in diameter, 14.6cm in height, with a total fluid volume capacity of 0.6L. Aluminium was chosen as the initial material for the intensified device because of its excellent printability, high thermal conductivity, and structural strength.
“The device can also be manufactured using other materials, such as emerging high thermal conductivity polymers and metals. Additive manufacturing methods like 3D printing are often cost-effective over time because it takes less effort and energy to print a part versus traditional manufacturing methods,” said Lonnie Love, Lead Manufacturing Researcher at ORNL.