Reducing the cost of CO2 capture from flue gas is essential if carbon capture and storage is to be widely deployed as a low emissions coal technology for power generation.
The premise of developing a novel gas-liquid contactor is that without a “radical rethink” of the capture technology substantial cost reductions will not occur.
The gas velocity sets the contactor column diameter of a gas-liquid contactor and has a large influence on both the capital and operating costs.
The overarching objective of this study was to test a novel contactor concept. A new gas-liquid contactor was designed to widen the gas velocity operating window, which significantly restricts conventional contactor technologies, but not at the expense of higher pressure drop.
The novel Rotating Liquid Sheet (RLS) contactor developed not only achieved a significantly wider gas velocity operating window, it also eliminated the need for the solid packing elements used in conventional packed beds.
The potential cost reductions are as a result of eliminating conventional column packing, reducing or eliminating the need for external flue gas pumping and smaller contactors.
Overall capital cost savings are estimated to be approximately 30%, based on the elimination of the packing and the reduction in column diameter. Elimination of the flue gas blower provides a minor capital cost saving and, additionally, it provides the opportunity of a net reduction in electrical power consumption of 25%.
Other benefits include:
- The RLS contactor can be readily designed to deliver operating savings in other conventional chemical processes.
- Fluids with viscosity up to 50 mPas have been successfully run showing similar behaviour to low viscosity fluids and improved liquid sheet stability.
- The shorter residence time and the cyclonic nature of the gas flow may be particularly advantageous in dealing with flue gas streams with high ash, high SOx and high NOx levels as are typical of flue gas streams in Australian conditions.