Carbon capture is necessary to continue the use of existing fossil fuels while reducing CO2 emissions, and thereby mitigating global climate change. Due to the high degree of separation of air needed for oxyfuel combustion, membrane technology has risen in popularity for its small scale separation capabilities of oxygen enriched air. This technology will be useful in combustor design in the power generation and transportation fields by lessening the emission of CO2 from combustors.
Membrane separation material options generally fall into one of two categories, polymeric or ceramic. These two membrane types provide very different performance and operating characteristics. The first, polymer membranes, operates at ambient temperatures. Polymer membranes are usually considered for producing O2-enriched air. Polymer membranes and/or zeolites are good for oxygen separation. However, the purity of oxygen is not high, meaning, making it insufficient for oxyfuel combustion with efficient carbon capture. The second type is the high-temperature ceramic membrane, or Ion Transport Membranes (ITM). Ceramic membranes produce very high purity oxygen, but they require high operating temperatures and have higher material cost per productivity. The permeability (oxygen flux rate) of ITMs depends on the partial pressure of O2 in the oxygen-nitrogen mixture. Increasing the concentration of O2 by using O2-enriched air rather than air improves the performance of the ITM. Combining polymeric with ceramic membranes can improve the overall efficiency of the system.
The invention is a combustor including a polymer membrane structure for receiving air at an input and for delivering oxygen-enriched at an outlet. The first component is a polymer membrane, which produces oxygen-enriched air. The second component is an ion transport membrane (ITM), and it is used to produce high quality oxygen. Integrating the polymer and ceramic membranes with combustion systems, such as gas turbine combustion chambers, can provide high temperature environment and high oxygen flux rates. This allows for large concentration gradients across the membrane, which is needed to achieve high fluxes of oxygen. Moreover, fuel oxidation converts chemical to thermal energy and maintains the high temperature required to activate the materials of the oxygen transport membrane. The two components provide high purity oxygen to burn with the fuel producing CO2 and water vapor. The water vapor can be separated by cooling, allowing for the CO2 to be easily captured, thus making the combustor carbon-free.
- Increases efficiency
- High stability
- Reduced volume/surface area of membranes
- Low material cost