(702a) Low-Pressure Sweep Membrane Modules for Carbon Dioxide Capture

To mitigate the harmful effects of global climate change, CO₂ in power plant flue gas must be captured and either sequestered or utilized in processes such as enhanced oil recovery.  Membrane technology is an attractive CO₂ capture option because of advantages such as energy-efficient passive operation, tolerance to acid gases and oxygen, no hazardous chemical emissions or handling issues, minimal water requirements, and no steam use requiring modifications to the existing boiler.

Working with DOE, MTR has previously demonstrated the feasibility of a two-step membrane process design to recover CO₂ from power plant flue gas.  The second step of this process is a selective sweep membrane module that strips CO₂ from the flue gas and recycles it back to the boiler with the incoming combustion air.  MTR is developing a membrane module specifically designed for high gas flow, low pressure, sweep operation.  These membrane modules contain up to 500 m² of membrane area, which is 10 to 20 times the membrane area of modules currently being used for flue gas CO₂ capture.  These large area modules will reduce the manifolding complexity, footprint, and cost of the very large membrane plants required for flue gas treatment.  By lowering the pressure drop through the modules, less compression/blower energy is needed to move gases through the module, which reduces the parasitic energy loss of the capture process.  In this presentation, results of the development work to date and future plans, including slip stream field testing at the National Carbon Capture Center (NCCC) operated by Southern Company in Birmingham, AL, will be discussed.

The development of large, efficient, low cost, sweep membrane modules is an enabling technology for membrane CO₂ capture and sequestration systems.  MTR is investigating several alternative process designs to remove CO₂ from coal power plant flue gas, and while all of the designs use a membrane contactor to recycle CO₂ to the power plant boiler, the second CO₂ separation unit need not be a membrane unit.  The selection of different hybrid separation technologies, hybrid process designs, and process economics will be presented.