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Oxygen fired pulverised coal combustion (Oxy-Fuel), offers a low risk step development of existing pf power generation technology to enable CO2 capture and storage.
Oxy-firing of PF in boilers involves the combustion of pulverised coal in a mixture of oxygen and recirculated flue gas in order to reduce the net volume of flue gases from the process and to substantially increase the concentration of carbon dioxide (CO2) in the flue gases – compared to the normal pulverised coal combustion in air. Oxygen combustion combined with flue gas recycle increases the CO2 concentration of the off-gases from around 15% for pf up to a theoretical 95%. Oxy-combustion is likely to give increased fuel flexibility (same as current pf).
Oxy-fuel technology is important to power and coal companies at an international level for the following reasons:
There are a number of variants for the proposed oxy-firing of PF boilers, but in simple terms the technology involves modification to familiar PF technology to include oxygen separation; flue gas recycling; and CO2 compression, transport, and storage (Figure 1). Relatively pure oxygen is mixed with a proportion of either wet or dry flue gas taken down stream of the particulate cleaning plant (typically 70% of the total gas flow) and blown into the wind box of the boiler. Primary air to sweep the pulverising mills is substituted with dry flue gas.
The net result of this combustion process is a concentrated stream of CO2, that enables the CO2 to be captured in a more cost effective manner compared to post combustion capture of CO2 from an air-fired boiler.
The specific reasons for considering oxy-fuel as an option for clean coal technology development are as follows:
Oxy-fuel Technology Status
The full-scale application of oxy-fuel technology is still under development. However, laboratory and theoretical work has provided an initial understanding of design parameters and operational considerations. In addition there have been a number of investigations using pilot-scale facilities in the US, Europe, Japan, and Canada. Studies have also assessed the feasibility and economics of retrofits and new power plant. Some of the conclusions that can be drawn from the findings to date are as follows:
CCSD FEASIBILITY STUDY
An oxy-fuel working group was established under the Australian Coal Association COAL21 program and includes the following organisations: CS Energy, Stanwell Corporation, Tarong Energy, Ishikawajima-Harima Heavy Industries (IHI) , IHI Engineering Australia (IEA), Cooperative Research Centre for Coal in Sustainable Development (CCSD), Center for Coal Utilization, Japan (CCUJ), Cooperative Research Centre for Greenhouse Gas Technologies (CO2CRC), Xstrata Coal, Australian Coal Association Research Program (ACARP), & University of Newcastle. The group was formally ratified through the signing of an MOU in September 2004.
The main purpose of the Japan-Australia working group is to carry out a detailed 2 year engineering feasibility study on oxy-fuel technology with three specific deliverables:
The overarching goals of the study are two fold: first, to provide a detailed engineering assessment of the potential application of oxy-firing for electricity generation, and to develop an engineering capability in Australia and overseas to build oxy-fuel plants in the future.
CS Energy’s No. 4 (30 MWe) Unit at Callide A Power Station located near Biloela in Central Queensland (Australia) has been selected as the basis of the study.
The Callide A Oxy-fuel Feasibility Study has been broken into 5 tasks:
For more information contact:
Dr Chris Spero