(433b) The Design of a New Membrane Contactor for CO2 Capture

MTR is developing a new membrane process to capture and sequester CO2 from power plant flue gas. A key component in this process is a membrane contactor that selectively removes CO2 from flue gas exhaust stream and recycles it to the power plant boiler. Because the volume of the flue gas is very large and the driving force for CO2 permeate is very low, an economical and small footprint, very large membrane contactor is required. We are developing a plate-fame contactor for this application.

Counter-current sweep is a traditional and effective way to introduce sweep in plate-fame contactor but counter-current sweep contactor is mechanically very difficult to make and the pressure drop in the sweep side is another issue. We are developing a new design: cross-flow sweep. Computational Fluid Dynamics (CFD)   is used to design the cross-flow sweep modules.  Our base case was developed for use in a 1 MW_e power plant, which produces approximately 1 m³ (STP)/s of flue gas.  The feed gas contains 10% CO₂ at a pressure of 2 bar, and the module area is adjusted to produce a residual stream containing 2% CO₂ (80% CO₂removal). These are close to the conditions that this type of contactor would be exposed to when being used to treat coal power plant flue gas.  Our base case module has a 1 m x 1 m module footprint.

Several design parameters are discussed:

1)      Sweep ratio which is the volume ratio of the gas between two sides of membrane

2)      Performance comparison between using counter-current sweep and cross-flow sweep

3)      Multi streams of feed or sweep

4)      Module with different ratios of length to width

5)      Partial counter-current designs

In all the cases which have different design parameters the membrane contactor separation performance and pressure drop inside the module are compared.