Colloquium

Silica glass hollow fibres At the same AIChE meeting, the virtues of hollow fibre membranes made from silica glass in gas separation applications were promoted by Yaw Yang of PPG Industries Inc, Pittsburgh. In contrast to conventional polymeric membranes, the glass fibres can be made with fine pores and narrow pore size distribution. They also resist high temperatures and the corrosive effects of acids and organic compounds. According to Yang, they outperform polymeric types in both permeability and selectivity. Applications already demonstrated by PPG include separation of CO2 from methane, nitrogen from methane, oxygen from nitrogen, and Freons from air. Other likely applications include dehumidification of air, recovery of organic vapours, high temperature membrane reactors and liquid phase separation of organic solvents, Yang said.

Michaeal Hsu, president of Zytek, says that many oxidation processes have potential for fuel cell cogeneration, pointing out that chemical conversion combined with fuel cell electricity production is more economic than burning ammonia and recovering heat in the conventional way. Another project announced at the same meeting was a 400 kW phosphoric acid fuel cell to be installed by Westinghouse Electric, Pittsburgh, at a Norsk Hydro chor-alkali plant at Rafnes, Norway. The fuel cell device, due to be operating in the first half of 1992, will generate power from hydrogen off- gas; some of this will be supplied from the chlor-alkali plant and some will be a mixture with methane from a nearby ethylene plant. Power conversion efficency is said to be 50%, compared with 35-40% for conventional thermo-electric plants. Dow Chemical Canada Inc also tried a membrane based fuel cell in a chloralkali plant some time ago.

Colloquium A three-day colloquium on membrane science and technology will be held in Aachen, Germany, 1921 March. The meeting is sponsored by GVC.VDI Gesellschaft fur Verfahrenstechnik und Chemieingenieurwesen of Dusseldorf and the Aachen Institut fur Verfahrenstechnik, RWTH (see Calendar).

New award The European Society for Membrane Science & Technology, ESMST, has instituted an annual medal and prize, of Ecu 1000, for contributions to the field of membrane science and technology. The 1991 award will be made for the best scientific disertation accepted by ESMST in 1989 and 1990. It will be presented during the international membrane symposium at Twente in the Netherlands in June (see Calendar).

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Fuel cells At the 1990 Fuel Cell Seminar, held Nov 25-28 in Phoenix, Arizona, USA, details were given of a solid oxide fuel cell (SOFC) based on a ceramic membrane. It is understood that the fuel cell, made by Ztek Corp, Waltham, Massachusetts, USA, will be tried out in a demonstration project for cogeneration of electric power at a chemical plant in Taiwan. The SOFC employs the ceramic membrane instead of electrolyte, and ammonia and oxygen are the feed gases. The ammonia is oxidised to nitric acid, for subsequent production of ammonium nitrate, and electric power is coproduced.

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Electrochemistry competes with ultrafiltration An electrochemical process for wastewater treatment, which is said to be much cheaper than ultrafiltration, has been introduced by Sintra GmbH, Munich, Germany. The process deals with emulsions of heavy metals, surfactants, oils and other hydrocarbons, at a cost of $0.02-0.03/m 3 of wastewater compared to $0.05-0.13 for ultrafiltration, so the company claims, at throughputs between 2 and 2,000 1/min. The electrochemical reactor consists of an aluminium tube anode which sits on spacers above a steel end plate acting as cathode. After preconditioning to bring pH between 6.5 and 8 and conductivity to 3 millisiemens, wastewater is passed through the reactor under a 40 volt potential. At the anode, aluminium hydroxide is

Membrane Technology