|Source:||Oak Ridge National Laboratory|
|Date:||1/1/94 Record No.: 10059|
|Contact:||Dave Stinton, 615-574-4556|
Gas Clean-up with Ceramic Composite Filters
They have a long history in CVD for coating nuclear fuel with continuous fiber ceramic composites, and are now doing chemical vapor "Infiltration." A Nikalon fiber preform is infiltrated with CV Silicon Carbide, to make tougher high temperature materials impervious to breakage by thermal shock. Near-term applications include filters for PFBC fly ash and char. (Commercially available candle filters aren't tough enough.) In work funded by METC, 3-M won the bid to commercialize, and is making 5' candles prototypes, replacing the traditional clay or glass binder with CV Si Carbide, making it very resistant to corrosion. They performed well in tests by Westinghouse. (Not related to EPRI's candle filter project in the U.K.)
Applications work on alloys, ceramics for corrosion problems: Iron Aluminide alloys have superb resistance to sulphadizing; e.g., in H2S in coal gasification (not the same as sulfates in combustion). Good structurally only to 600íC, but as a cladding to 1100íC in sulfur environment and to 1300íC in an oxidizing environment.
An application has been developed to create a porous sintered filter metal. Amitech is the licensee for the invention, and makes the powder. In 1987, the Pall Corp. and Amitech entered into an informal collaboration with ORNL, and Pall is making filters from this material, and is replacing its own product on the market. The market is small currently, but since hot gas cleanup technology doesn't exist--plants are designed more conservatively than may be necessary, particularly in the area of heat recovery. The technology may make 700íC flue gas cleanup possible. A utility could do the tests needed to go to the next step.