Oxyfuel:
Using Pure Oxygen to Produce Pure CO2
In the oxyfuel process, a fuel like coal is combusted with pure oxygen instead of air, with exhaust gas added to regulate the combustion temperature. The resulting flue gas consists of almost pure CO2 along with some steam.
Cooling the flue gas enables the CO2 to be separated from the steam, which condenses to water at low temperatures. The CO2-dense flue gas is then scrubbed using conventional equipment, which removes the minimal amounts of dust, sulfur dioxide, and nitrogen oxides it contains. The success of the oxyfuel method depends to a considerable degree on determining how thoroughly these gases must be scrubbed from the CO2 before it can be safely transported and stored.
Cooling the flue gas enables the CO2 to be separated from the steam, which condenses to water at low temperatures. The CO2-dense flue gas is then scrubbed using conventional equipment, which removes the minimal amounts of dust, sulfur dioxide, and nitrogen oxides it contains. The success of the oxyfuel method depends to a considerable degree on determining how thoroughly these gases must be scrubbed from the CO2 before it can be safely transported and stored.
It takes a lot of energy to produce the pure oxygen with which the fuel is combusted, but comparatively little to scrub the CO2 after combustion. Another challenge is to improve control of the combustion process in the boiler. Innovative solutions to meet these challenges will be important milestones towards rolling out the oxyfuel process on a utility scale.
With oxyfuel, the key challenge is to manage the combustion of coal with pure oxygen. We're currently operating a 1 MW oxyfuel test unit at E.ON UK's Ratcliffe power station, a coal-fired facility located in central England. Successful trials have demonstrated that the test unit can simulate the combustion process under real operating conditions. The trials are giving us important insights into the stages of the combustion process and the impact oxyfuel technology has on the entire generation process. The results of the operational trials will be incorporated into an oxyfuel combustion unit we're developing together with a British engineering company partnering with us in the trials. The next stage of R&D is to install this unit in a larger pilot plant and to run tests that will refine the technology and help make it commercially viable.
The pure oxygen needed for oxyfuel combustion is produced through cryogenic air separation. The equipment for this process, which involves liquefying air, is widely used in industrial applications. But it's an energy-intensive process and, for application in a power plant, will need to be refined significantly or replaced by an alternative process. Basic research into membrane technology, which may help make air separation more efficient, is currently under way.
In a project called OXYCOAL, we're partnering with other companies and research institutes to conduct important basic research on smaller-scale test units. The project's purpose is to significantly enhance the efficiency of the oxyfuel process and to make oxyfuel a viable, long-term option in a sustainable climate-protection strategy.
Another important part of our oxyfuel effort is our involvement in a project called ADECOS (Advanced Development of the Coal-fired Oxyfuel Process with CO2 Separation) which focuses on the technical and commercial development of oxyfuel technology. Its main objectives are to optimize combustion processes, to develop larger-scale oxyfuel combustion units, and to study the emissions behavior of oxyfuel units and their susceptibility to dirt and slag buildup.
The pure oxygen needed for oxyfuel combustion is produced through cryogenic air separation. The equipment for this process, which involves liquefying air, is widely used in industrial applications. But it's an energy-intensive process and, for application in a power plant, will need to be refined significantly or replaced by an alternative process. Basic research into membrane technology, which may help make air separation more efficient, is currently under way.
In a project called OXYCOAL, we're partnering with other companies and research institutes to conduct important basic research on smaller-scale test units. The project's purpose is to significantly enhance the efficiency of the oxyfuel process and to make oxyfuel a viable, long-term option in a sustainable climate-protection strategy.
Another important part of our oxyfuel effort is our involvement in a project called ADECOS (Advanced Development of the Coal-fired Oxyfuel Process with CO2 Separation) which focuses on the technical and commercial development of oxyfuel technology. Its main objectives are to optimize combustion processes, to develop larger-scale oxyfuel combustion units, and to study the emissions behavior of oxyfuel units and their susceptibility to dirt and slag buildup.
