Metallic Filters for Hot-Gas Cleanup

Hot gas clean-up is one of the key technological barriers remaining in the development of advanced coal-fired power cycles.

These advanced coal-fired power cycles include pressurized fluidized bed combustion (PFBC) and integrated gasification combined cycles (IGCC).

The successful development of these high-efficiency, low-emission power plant concepts is premised on efficient removal of fine particles and gaseous contaminants from high-temperature, high-pressure combustion gas streams.

Although composite and monolithic ceramic candle filters have been investigated over the last two decades, recent analysis suggests that the metallic candle filter is one of the most promising approaches to hot-gas clean-up for advanced coal conversion technologies.

A 60.3-mm diameter, rolled and welded, prototype filter sample, having a 0.5-mm wall, fabricated from Ni-Cr-2xAl-Fe powder.

The ability to roll and weld these types of filters will allow porous sintered samples to be placed in a commercial PFBC system for long-term corrosion testing and evaluation.

Conceptual manufacturing process for metal candle filters.

Iver Anderson with materials used to create the metallic filter material. The photo shows the powdered metal, the sintering molds and the material.

The corrosion resistance of the filter materials is being evaluated under simulated PFBC/IGCC gaseous environments to determine the optimum alloy composition and filter structure.

The corrosion tests provide a means to estimate the service lives of experimental filter materials when subjected to either normal or abnormal PFBC/IGCC plant operating conditions.

A micrograph of the metallic filter material shows the necks between the powder particles.