Monday, May 21, 2012

MIT's New Ceramic O2 Separation Membrane Kills Multiple Birds With One Stone

MIT researchers are investigating ceramic membranes as a way to reduce carbon dioxide emissions in powerplants. In their system, the air (red dots) that’s needed for combustion passes over a ceramic membrane (red layer). Only oxygen passes through the membrane, mixing with fuel (black and green dots) to produce a pure stream of carbon dioxide and water. After evaporating water, carbon dioxide can then be captured and stored. _MITNews

A new O2 separation membrane from MIT scientists, is being touted as a potential CO2 reduction breakthrough. But fortunately, in reality it is far more than just a masturbation aid for carbon hysterics. In reality, a cheap way of concentrating O2 in combustion chambres while eliminating N2, provides a powerful anti NOx tool while at the same time making combustion more efficient. In addition, by making it cheaper to sequester CO2 in purified form, it may also help create a lucrative market in large-scale, pure CO2 for a number of commercial purposes. More about the technology:
Now researchers at MIT are evaluating a system that efficiently eliminates nitrogen from the combustion process, delivering a pure stream of carbon dioxide after removing other combustion byproducts such as water and other gases. The centerpiece of the system is a ceramic membrane used to separate oxygen from air. Burning fuels in pure oxygen, as opposed to air — a process known as oxyfuel combustion — can yield a pure stream of carbon dioxide.

The researchers have built a small-scale reactor in their lab to test the membrane technology, and have begun establishing parameters for operating the membranes under the extreme conditions found inside a conventional powerplant. The group’s results will appear in the Journal of Membrane Sciences, and will be presented at the International Symposium on Combustion in August.

...The air we breathe is composed mainly of nitrogen (78 percent) and oxygen (21 percent). The typical process to separate oxygen from nitrogen involves a cryogenic unit that cools incoming air to a temperature sufficiently low to liquefy oxygen. While the freezing technique produces a pure stream of oxygen, the process is expensive and bulky, and consumes considerable energy, which may sap a plant’s power output.

Ghoniem says ceramic membranes that supply the oxygen needed for the combustion process may operate much more efficiently, using less energy to produce pure oxygen and ultimately capture carbon dioxide.

...The group is now gauging the system’s performance at various temperatures, pressures and fuel conditions using their laboratory setup. They have also designed a complex computational model to simulate how the system would work at a larger scale, in a powerplant. They’ve found that the flow of oxygen across the membrane depends on the membrane’s temperature: The higher its temperature on the combustion side of the system, the faster oxygen flows across the membrane, and the faster fuel burns. They also found that although the gas temperature may exceed what the material can tolerate, the gas flow acts to protect the membrane.

“We are learning enough about the system that if we want to scale it up and implement it in a powerplant, then it’s doable,” Ghoniem says. “These are obviously more complicated powerplants, requiring much higher-tech components, because they can much do more than what plants do now. We have to show that the [new] designs are durable, and then convince industry to take these ideas and use them.” _MITNews
In addition to use in large power plants, the technology may eventually be used in a wide range of smaller internal combustion engines, for improved combustion and reduced NOx emissions.

High volume purified CO2 can be sold in many markets, from oil & gas to foods to chemicals etc. And in the event of a new ice age, a controlled release of CO2 into the atmosphere might keep larger areas of the planet habitable -- although in reality the heat retaining properties of CO2 in the atmosphere are proving to be far less potent than the alarmists had predicted.



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