Oak Ridge National Laboratory (ORNL) engineers have 3D printed a unique aluminum device to enhance CO2 capture from fossil fuel plants and other industrial processes.
According to the scientists, the first-of-its-kind, low-cost aluminum device focuses on a key challenge in conventional absorption of carbon using solvents – a process known to produce heat and limit carbon capture’s overall efficiency.
Absorption is one of the most commonly used and economical methods for capturing CO2. It places a flue-gas stream from smokestacks in contact with a solvent such as monoethanolamine (MEA) that reacts with the gas.
The team tested their novel circular device inside a 1-meter-tall by 8-inch-wide absorption column consisting of seven commercial stainless-steel packing elements.
The ‘intensified’ device – which comes with a mass-exchanging contactor-driven heat exchanger – was installed in the top half of the column between the packing elements.
3D printing the device ensured that it could be integrated within the column, without disturbing the geometry, thus maximizing the contact surface area between the gas and liquid streams.
“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,” notes principal investigator, Dr. Xin Sun
Embedded coolant channels were also added inside the packing element’s corrugated sheets to allow for heat exchange capabilities.
The final prototype measured 20.3 centimeters in diameter, 14.6 centimeters in height, with a total fluid volume capacity of 0.6 liters.
According to Lonnie Love, the intensified device’s creator, other materials such as emerging high thermal conductivity polymers and metals can also be used to manufacture such devices.
Two separate experiments – one that varied the CO2-containing gas flow rate and one that varied the MEA solvent flow rate – were conducted to determine which operating conditions produce the greatest benefit to carbon capture efficiency.
Both experiments produced substantial improvements in the carbon capture rate and demonstrated that the magnitude of the capture consistently depended on the gas flow rates.
The study also showed a peak in capture at 20% of carbon dioxide concentration, with percent of increase in capture rate ranging from 2.2% to 15.5% depending on the operating conditions.
Image and content: Carlos Jones, Michelle Lehman/ORNL
