A scoping study on Oxy-CFB technology as an alternative carbon capture option for Australian black and brown coals
A roadmap for future Oxy-CFB deployment is presented, revealing that due to the current status of Oxy-CFB development compared to Oxy-PF, there is greater uncertainty regarding future technology development and deployment. Common drivers include a potential future cost of CO2, and development of higher USC efficiency commercial plants. The roadmap indicates a delayed application of higher temperature steam conditions for CFB compared to PF based on IEA projections. Although Foster Wheeler indicate guarantees can currently be provided for USC CFB units, the commercial risk of their deployment must be considered to be greater. Noted for Oxy-CFB is the current need for more fundamental and applied research related to the uncertainty of coal performance and gas quality control, in order to define the appropriate Oxy-CFB flowsheet.
Circulating Fluidised Bed combustion (CFBC) units use bed materials (such as silica sand) in which to combust coal at as temperature of about 900°C. CFBCs can tolerate varying particle size (from micron size as in pulverised coal-fired units to coarse feed size around ~10mm), and varying fuel quality (from anthracite to lignite, petroleum coke, biomass, and opportunity fuels). CFBC plants were originally developed for use with low-quality and 'difficult-to-burn' fuels – high sulfur, high ash, low calorific value and combinations – or where fuel flexibility was required, such as the availability of variable quantities of wastes for co-firing with more traditional fuels. However, gradually CFBCs have established themselves as being suitable for almost all types of solid and several liquid fuels.
Oxy-CFB operating at atmospheric pressure is emerging as a serious technology option for CO2 capture. This is demonstrated by the rapid design and construction of the world’s first Oxy-CFB pilot-scale facility at CIUDEN in Spain, which was commissioned in September 2011. The facility is designed and operated by Foster Wheeler, and will primarily test non-lignitic coals. In addition to the 30MWth Oxy-CFB unit, the facility also has a 20 MWth Oxy-PF unit and a biomass gasifier. A 300 MWe Oxy-CFB plant is also under consideration in the adjacent Compostilla Power Station.
A roadmap for future Oxy-CFB deployment is presented, revealing that due to the current status of Oxy-CFB development compared to Oxy-PF, there is greater uncertainty regarding future technology development and deployment.