Membrane-Based Oxygen-Enriched Combustion

Abstract

The use of oxygen-enriched air, instead of ambient air, can significantly improve the energy efficiency of combustion processes and reduce the cost of CO 2 capture from flue gases throughout manufacturing industries. This study examines the overall energy savings and economic benefits that can be obtained using oxygen-enriched combustion based on novel membranes and processes to produce oxygen-enriched air. Membrane processes using low-pressure air as a countercurrent sweep in the permeate were used to minimize the energy cost of producing oxygen-enriched air. High-performance thin film composite membranes based on a series of perfluoropolymers and bench-scale spiral-wound modules were prepared, and showed oxygen permeance as high as 1200 gpu (1 gpu = 10 −6 cm 3 (STP)/cm 2 •s•cmHg) combined with O 2 /N 2 selectivity of 3.0. The membrane-based oxygen-enriched combustion processes show good energy savings (defined as the fuel savings less the energy consumption of producing oxygen-enriched air) and economic benefits (defined as the value of fuel saved less the operating cost of producing oxygen-enriched air), especially at flue gas temperatures higher than 1090 °C (or 2000 °F). For example, at a flue gas temperature of 1649 °C (or 3000 °F), membrane-based oxygen-enriched combustion shows a net energy savings of 35% and a net economic benefit of 29%, compared to the combustion process with air. The effect of oxygen-enriched air on NO x emissions in a natural gas furnace was also experimentally investigated.

Steam/oxygen biomass gasification at pilot scale in an internally circulating bubbling fluidized bed reactor

“…Moreover, the availability of a technology based on enriched-air gasification can make it suitable for RDF gasification [37,38], thus expanding the fields of its applicability. Studies on low cost technology for oxygen-enriched air production are giving an important sustenance to the feasibility of such applications [39][40][41][42].…”

Gas permeation in thin films of “high free-volume” glassy perfluoropolymers: Part II. CO2 plasticization and sorption

“…The CO 2 /CH 4 selectivity of~5 for AF 2400 makes it a potential candidate for natural gas separations. Although amorphous perfluoropolymers have been used for oxygen enrichment of air and CO 2 separation in some cases, they have not been extensively studied in thin film form [5]. Recently, Horn and Paul demonstrated that thin films undergo significantly greater CO 2 plasticization effects than thick films; the observed responses are affected by the aging time and CO 2 exposure protocol used [6e8].…”

The optimal point within the Robeson upper boundary

“…We have assumed a reasonable thickness of the selective layer of 1µm (Koros and Mahajan, 2000;Lin et al, 2013;Cabasso and Lundy, 1986;Baker, 2002). Permeance cannot be used instead of permeability to find minimum costs, since it is a function of how the membrane is engineered.…”