Energy futureU.K. energy company to demonstrate its oxyfuel technology

Crawley, West Sussex, U.K.-based Doosan Babcock Energy is to start a significant new project to demonstrate its oxyfuel technology for carbon capture in coal-fired power plants. Carbon capture and sequestration (CCS) requires the separation of carbon dioxide from the main component in the flue gas — normally nitrogen. In oxyfuel firing, the separation is achieved by separating air into its two primary components, oxygen and nitrogen and firing the coal in the oxygen — which is diluted as necessary by recycled flue gas, predominantly carbon dioxide.

The £7.4 million Oxyfuel 2 project is being supported by the Department for Business Enterprise and Regulatory Reform (BERR) under its Hydrogen Fuel Cells and Carbon Abatement Technologies (HFCCAT) Demonstration Program. There is support too from a plethora of industrial sponsors and university partners, including Scottish and Southern Energy, E.ON, Drax Power, ScottishPower, EDF Energy , Dong Energy Generation , Air Products, and Imperial College and Nottingham University.

Doosan Babcock will modify its Multi Fuel Burner Test Rig at Renfrew to accommodate oxyfuel firing on pulverised coal with recycled flue gas and demonstrate the operation of a full scale 40 MW burner for use in coal-fired boilers. The upgrade of the burner test facility is expected to be complete early in 2009, with the first oxyfuel combustion demonstration by the end of March that year.

The technology

Oxyfuel combustion is the process of firing a fossil-fueled power plant with an oxygen-enriched gas mix instead of air. Almost all of the nitrogen is removed from input air, yielding a stream which is about 95 percent oxygen. Firing with pure oxygen would result in too high a flame temperature, so the mixture is diluted by mixing with recycled flue gas. The recycled flue gas can also be used to carry fuel into the boiler and ensure adequate convective heat transfer to all boiler areas.

There are many benefits to oxyfuel combustion. It produces approximately 75 percent less flue gas than air fueled combustion, and produces exhaust consisting primarily of CO2 and H2O. Oxyfuel combustion produces a CO2-rich flue gas ready for sequestration. Another advantage: Because nitrogen from air is not allowed in, nitrogen oxide production is greatly reduced. There are other benefits. There is also a downside. Because of the energy and economic costs of producing oxygen, an oxyfuel power plant is less efficient than a traditional air-fired plant. If there were no need to reduce CO2 emissions, oxyfuel would not be competitive.