Metallic Filters for Hot Gas Clean-up

摘要

Compared to ceramic filters, metallic filters can offer increased resistance to impact and thermal fatigue, greatly improving filter reliability. Successful development of metallic filters with high temperature oxidation/corrosion resistance for fly-ash capture is a key to enabling advanced coal combustion and power generation technologies. A beneficial metallic filter structure, composed of a thin wall (～0.5mm) tube with uniform porosity (～30%), is being developed using a unique spherical powder processing and partial sintering approach, combined with porous sheet rolling and resistance welding. Alloy choices based on modified superalloys, e.g., Ni-16Cr-4.5Al-3Fe (wt.%), are being tested in porous and bulk forms for oxide (typically alumina) scale stability in simulated oxidizing/sulfidizing atmospheres found in advanced combustion systems. New studies are exploring the correlation between sintered microstructure, tensile strength, and permeability of porous sheet samples.