Clear the air

The US Office of Fossil Energy's National Energy Technology Laboratory (NETL) is working with Air Products and Chemicals to perfect a novel means of producing oxygen in high volumes.

The Ion Transport Membrane (ITM) Oxygen production technology reportedly requires less energy and offers lower capital costs than conventional technologies.

NETL and Air Products teamed up in 1998 to develop the membrane material and the process. Now, the process is being validated in a five-tons-per-day prototype facility producing high-purity oxygen.

The ITM Oxygen technology is a radically different approach to producing low-cost, high-temperature oxygen. Existing technology is energy intensive and requires air to be cooled to approximately -280F: the temperature at which air becomes a liquid and oxygen can be separated.

In contrast, the electrochemical properties of ITM Oxygen make it possible to selectively separate oxygen from a stream of air at high temperature and pressure.

In the ITM Oxygen process, oxygen in high-temperature, high-pressure air is ionised at the surface of a ceramic membrane and transported through the membrane via a pressure gradient.

The oxygen ions recombine as pure oxygen on the permeate or low-pressure side and leave a stream of hot, compressed, oxygen-depleted air on the feed or non-permeate side.

The energy of the hot non-permeate stream is recovered through conversion to electrical energy and steam.

As part of the continuing project, a subscale engineering prototype facility was designed and built to test multiple membrane modules under commercial conditions.

Testing in the prototype facility is providing engineering data to support the design of a 150-tons-per-day test facility that will then co-produce oxygen and power.

The larger facility is expected to be commissioned in late 2010.