Techno-economic evaluation of a PVAm CO2-selective membrane in an IGCC power plant with CO2 capture
Multi-scale and/or multi-disciplinary approach to process-product innovation
Analysis of Environmental Issues (T3-3b)
Keywords: IGCC, membrane, CO2, capture, power
The high partial pressure of CO2 in a water-gas-shifted syngas stream in an Integrated Gasification Combined Cycle offers an excellent driving force for membrane separation. The challenge has been to find an inexpensive membrane that has a high enough selectivity to separate CO2 without losing a significant fraction of hydrogen to the CO2 stream. A polyvinyl amine membrane is under development at the Norwegian University of Science and Technology that permeates CO2 by a fixed-site-carrier mechanism, which allows both a high selectivity over hydrogen (approximately 100) and a reasonable permeance (0.05-0.1 m3(STP)/m2.bar.h).The polymeric membrane can be supported on polysulfone hollow fibres and may therefore be produced in bulk without drastic modification of current membrane spinning techniques.
Published data for an operating power plant, the ELCOGAS 315 MWe Puertollano plant, was used as a basis for the simulation of an integrated gasification combined cycle process with CO2 capture. This incorporated the fixed site carrier PVAm membrane to separate the CO2 from a CO-shifted syngas stream. Continuous-rig laboratory permeance data was used in an in-house membrane model integrated with Aspen Hysys®. The study included the effect of membrane selectivity, CO2 recovery and the position of the shift reaction in the process route on the plant efficiency and cost.
It appears that the modified process, using a sour shift catalyst prior to sulphur removal, could achieve greater than 85% CO2 recovery at 95 vol% purity. The efficiency penalty for such a process, including CO shift and CO2 compression, would be approximately 10 percentage points. The membrane section compared favourably with respect to the energy consumption of physical solvent CO2 capture and was similar in capital cost.
Presented Tuesday 18, 09:25 to 09:45, in session Analysis of Environmental Issues (T3-3b).
