Membrane gas-solvent contactor pilot plant trials at Vales Point Power Station
Membrane gas-solvent contactors are a hybrid technology in which traditional solvent absorption occurs within a membrane module. The technology involves the transfer of CO2 from the flue gas and through a hollow-fibre membrane, where it is chemically absorbed into the solvent. This takes advantage of the highly selective nature of solvent absorption technology, while the membrane acts to physically separate the solvent and gas phases. The process enables more CO2 to be quickly transferred into the solvent phase requiring significantly reduced equipment sizes when compared with conventional CO2 absorption systems using packed beds.
At the Vales Point power plant in NSW, the research team conducted a world’s first continuous pilot scale demonstration of capturing carbon dioxide using membrane gas-solvent contactor technology, while simultaneously undertaking carbon dioxide (CO2) capture and solvent regeneration. The project clearly identified commercially available membrane contactors that can be successfully implemented for CO2 capture from flue gas using conventional solvents, as well as the subsequent solvent regeneration at elevated temperature. The pilot plant campaign determined the optimal operational conditions, especially for solvent regeneration, that enabled efficient carbon capture operation over an extended period.
The membrane was designed to process 3 – 5 kg/hr of flue gas, utilizing 30 wt% MEA circulating with a flowrate of 0.1-0.12 L/min through both membrane contactors. Solvent regeneration was achieved through a steam sweep (2 – 5 kg/hr), that heated the solvent to high temperature as well as reduced the partial pressure of CO2 on the permeate side of the membrane, promoting CO2 liberation.
The research aims included:
- Commissioning and trialling membrane contactor systems for solvent absorption from flue gas, utilising commercially available membrane modules.
- Trialling membrane contactor systems for solvent regeneration, utilising commercially available membrane distillation modules.
- Operation of the membrane contactor process in full continuous mode, with solvent absorption and regeneration occurring together for extended periods of time.
- Achieving the performance of the pilot plant with overall mass transfer coefficient for absorption >0.08 cm/s and for regeneration >0.05 cm/s.
- Detailed analysis of process performance to enable scale up design leading to future commercialisation of the membrane contactor process.