Oxyfuel Boiler Technologies

An emerging technology for CO2 capture from fossil fuel fired power plants involves burning the fuel with oxygen in an atmosphere of recycled flue gas, a process commonly known as O2/CO2 recycle combustion.

The advantages of this process include :

  • High concentration of CO2 in the flue gas
  • Reduced flue gas volume for further separation/purification
  • NOx reduction due to the absence of N2 in the combustion air
  • Lower investment cost

One bottleneck for large-scale applications is the large quantities of oxygen required, which can be met only with cryogenic air separators and result in a high energy penalty. Critical point remains the development of novel oxygen production while the use of oxygen in large-scale boilers constitutes a new research area. Furthermore another major issue, derived from the low technical maturity of this technology, is the need to support extended tests and evaluations in large scale test facilities and in pilot plants together with extensive validation test programs.

The ENCAP “oxy-fuel combustion” subproject has nominated two candidates for pilot testing in Phase II of the project :

  • A 30 MWth power plant, based on the ENCAP oxyfuel PF concepts, in which crucial technical oxyfuel related issues will be tested. The pilot plant will be erected next to the Schwarze Pumpe power station in Germany. After the first pilot plant test period it should be possible to start the construction of a 200 MWe demo plant that will operate under commercial conditions
  • 1 MWth Oxyfuel CFB plant (based on modifications to an existing test-facility)

Furthermore, worldwide the following activities will be realised:

  • A conceptual design of an 80 MWe air fired Circulating Fluidised Bed retrofitted to oxyfuel firing, developed by Alstom (www.netl.doe.gov, www.alstom.com)
  • A € 50 million investment by Total on a pilot oxy-fuel project in their Lacq plant at a sour gas field in S.W. France. The pilot plant will be a modification of an existing 50 MW thermal boiler and its conversion to an oxy-combustion boiler.