Membrane Process for Carbon Dioxide Capture
10:00 - 10:30
Level 0, between bld. 4 and 5
Anthropogenic emissions of carbon dioxide (CO2) from fossil fuel power plants potentially can lead to global climate change. Post combustion capture processes recover CO2 from the flue gas stream in which CO2 is relatively dilute. Among the technologies available for capture, membrane processes are of great interest due to cost competitiveness, robustness, and compactness.
Two projects to improve the viability of membrane processes are discussed. First, results from theoretical and experimental studies of the effect of spacer design on pressure drop in membrane modules are presented. Second, optimization of membrane and process design variables in an air-feed sweep configuration is reported.
Theoretical studies of the effect of filament spacing and angle on pressure drop are performed using computational fluid dynamics. Filament spacing has little effect but pressure drops increase dramatically as the angle between filaments increases. An asymmetric spacer has potential to offer low pressure drops comparable to traditional symmetric configurations. The computational results are validated with particle image velocimetry measurements of velocity fields. Additionally, the effect of spacer design and associated pressure drop on performance is quantified.
Membrane Technology and Research (MTR) proposed an air feed sweep system that significantly reduces capture cost. However, this reduction comes at the cost of reduced oxygen concentration in the boiler feed air. The effects of membrane transport properties and process operating pressures on performance are examined for various boiler feed oxygen concentrations. The CO2/N2 selectivity is varied over a broad range while the CO2 permeability is calculated according to the Robeson upper bound. The results are reported in terms of levelized cost of electricity (LCOE). A broad minimum in LCOE is found which decreases as oxygen concentration in the feed air decreases.