Knut Ingvar Åsen

Advanced zero emissions gas turbine power plant

The AZEP advanced zero emissions power plant project addresses the development of a novel zero emissions, gas turbine-based, power generation process to reduce local and global CO 2 emissions in the most cost-effective way. Process calculations indicate that the AZEP concept will result only in a loss of about 4% points in efficiency including the pressurization of CO 2 to 100 bar, as compared to approximately 10% loss using conventional tail-end CO 2 capture methods. Additionally, the concept allows the use of air-based gas turbine equipment and, thus, eliminates the need for expensive development of new turbomachinery. The key to achieving these targets is the development of an integrated MCM-reactor in which (a) O 2 is separated from air by use of a mixed-conductive membrane (MCM), (b) combustion of natural gas occurs in an N 2 -free environment, and (c) the heat of combustion is transferred to the oxygen-depleted air by a high temperature heat exchanger. This MCM-reactor replaces the combustion chamber in a standard gas turbine power plant. The cost of removing CO 2 from the combustion exhaust gas is significantly reduced, since this contains only CO 2 and water vapor The initial project phase is focused on the research and development of the major components of the MCM-reactor (air separation membrane, combustor, and high temperature heat exchanger), the combination of these components into an integrated reactor, and subsequent scale-up for future integration in a gas turbine. Within the AZEP process combustion is carried out in a nearly stoichiometric natural gas/O 2 mixture heavily diluted in CO 2 and water vapor The influence of this high exhaust gas dilution on the stability of natural gas combustion has been investigated, using lean-premix combustion technologies. Experiments have been performed both at atmospheric and high pressures (up to 15 bar), simulating the conditions found in the AZEP process. Preliminary tests have been performed on MCM modules under simulated gas turbine conditions. Additionally, preliminary reactor designs, incorporating MCM, heat exchanger, and combustor, have been made, based on the results of initial component testing. Techno-economic process calculations have been performed indicating the advantages of the AZEP process as compared to other proposed CO 2 -free gas turbine processes.

Preparation of anchored ceramic coatings on metal substrates: a modified sol-gel technique using colloidal silica sol

A single-step dip-coating technique was developed to produce stable films or washcoats of controlled thickness, surface area and pore-size distribution on alumina whisker-covered metal substrates (both flat plates and monoliths). Dip-coating slurries were prepared by dispersing fine porous powder in a colloidal silica sol. The method provided control over coating thickness and coating properties, such as pore-size distribution and surface area. The coating thickness could be varied between approximately 2 and 40 μm by selecting slurry composition and withdrawal speed in the dipping procedure. The pore-size distribution and surface area could be varied by changing type and amount of porous filler material in the dipping slurry. Uniform and bimodal pore-size distributions were obtained using silica and ZSM-5 molecular sieves, respectively, yielding coatings with surface areas between 60 and 400 m2g−1.