CO₂ Capture Membrane Process for Power Plant Flue Gas

Abstract

Because the fleet of coal-fired power plants is of such importance to the nation's energy production while also being the single largest emitter of CO 2 , the development of retrofit, post-combustion CO 2 capture technologies for existing and new, upcoming coal power plants will allow coal to remain a major component of the U.S. energy mix while mitigating global warming. Post-combustion carbon capture technologies are an attractive option for coal-fired power plants as they do not require modification of major power-plant infrastructures, such as fuel processing, boiler, and steam-turbine subsystems.In this project, the overall objective was to develop an advanced, hollow-fiber, polymeric membrane process that could be cost-effectively retrofitted into current pulverized coal-fired power plants to capture at least 90% of the CO 2 from plant flue gas with 95% captured CO 2 purity. The approach for this project tackled the technology development on three different fronts in parallel: membrane materials R&D, hollow-fiber membrane module development, and process development and engineering. The project team consisted of RTI (prime) and two industrial partners, Arkema, Inc. and Generon IGS, Inc.Two CO 2 -selective membrane polymer platforms were targeted for development in this project. For the near term, a next-generation, high-flux polycarbonate membrane platform was spun into hollow-fiber membranes that were fabricated into both lab-scale and larger prototype (~2,200 ft 2 ) membrane modules. For the long term, a new fluoropolymer membrane platform based on poly(vinylidene fluoride) [PVDF] chemistry was developed using a copolymer approach as improved capture membrane materials with superior chemical resistance to flue-gas contaminants (moisture, SO 2 , NO x , etc.). Specific objectives were  Development of new, highly chemically resistant, fluorinated polymers as membrane materials with minimum selectivity of 30 for CO 2 over N 2 and CO 2 permeance greater than 300 gas permeation units (GPU) targeted  Development of next-generation polycarbonate hollow-fiber membranes and membrane modules with higher CO 2 permeance than current commercial polycarbonate membranes  Development and fabrication of membrane hollow fibers and modules from candidate polymers  Development of a CO 2 capture membrane process design and integration strategy suitable for end-of-pipe, retrofit installation  Techno-economic evaluation of the "best" integrated CO 2 capture membrane process design packageIn this report, the results of the project research and development efforts are discussed and include the post-combustion capture properties of the two membrane material platforms and the hollow-fiber membrane modules developed from them and the multi-stage process design and analysis developed for 90% CO 2 capture with 95% captured CO 2 purity.iv

Membrane-based carbon capture from flue gas: a review

“…They predicted that such studies will shift Robeson's bound to the upper right corner of a Permeability/Selectivity plot having moderate selectivities and high permeabilities. Toy et al (2012), in a project for U.S. Department of Energy, synthesized a vinylidene fluoride (VDF)-based copolymer membrane (VDF-co-B). They observed that the bulky, high-dipole comonomer B helped to increase gas permeability in the polymer matrix, and its greater polarity enhanced the CO 2 affinity (solubility) of the matrix.…”

Assessment of Membrane Performance for Post-Combustion CO2 Capture

“…SO 2 is more condensable than CO 2 and therefore can plasticize the polymer, but it can also compete with CO 2 for sorption sites, leading to a reduction in CO 2 permeability. In tests with a polycarbonate membrane, a short-term test did not reveal any significant impact on CO 2 permeability, but a 20% loss of permeance was shown after continuous exposure to 300 ppm SO 2 over a period of 4 months . Li et al investigated the effect of SO 2 on a facilitated transport membrane using a mixed feed gas containing 5000 ppm SO 2 and showed that the CO 2 permeance declined by 17% and the CO 2 /N 2 selectivity by 20% due to competitive sorption …”

“…In tests with a polycarbonate membrane, a short-term test did not reveal any significant impact on CO 2 permeability, but a 20% loss of permeance was shown after continuous exposure to 300 ppm SO 2 over a period of 4 months. 24 Li et al investigated the effect of SO 2 on a facilitated transport membrane using a mixed feed gas containing 5000 ppm SO 2 and showed that the CO 2 permeance declined by 17% and the CO 2 /N 2 selectivity by 20% due to competitive sorption. 25 Nitric oxide in flue gases ranges from 10 to 500 ppm, mostly as NO and traces as NO 2 .…”