New technology that burns coal in oxygen rather than air is under test in the US, utilising Alstom advanced pulverised coal (PC) and circulating fluidised bed (CFB) boilers.

Alstom has completed the third phase of the oxyfuel-fired CFB in its 3 MWth pilot plant at the Power Plant Laboratories in Windsor, CT, using bituminous coal and a petroleum coke.

Based on the successful pilot scale results, Alstom is now developing a conceptual design of an 80 MW air-fired CFB plant retrofitted to oxyfuel firing, a design geared towards the first commercial demonstration plant of its kind in North America.

The tests demonstrated the successful operation of the CFB fired with high concentrations of oxygen instead of air. The tests also produced important data on heat transfer coefficients, combustion efficiency, emissions of major pollutants and trace emissions such as volatile organic compounds and mercury.

According to Dr Woody Fiveland, Senior Technical Fellow at Alstom’s Power Plant Laboratories: “The successful performance of oxyfuel firing during these tests is an important milestone in offering carbon capture ready solutions to our customers.”

Oxyfuel firing produces a flue gas of concentrated carbon dioxide, which can be captured and sequestered more easily. One promising scenario is to use the gas commercially for enhanced oil recovery and/or enhanced natural gas recovery, which also effectively sequesters it.