Sintered metal filters have been used for hot gas filtration in various plants in the chemical process, petrochemical and power generation industries. These filters can provide particulate capture efficiencies of 99.9% or better. The temperature for filtration has been as high as 600℃.
Metal filters can be designed with required strength at elevated temperatures, hot corrosion resistance and toughness to withstand the thermal and mechanical stresses.
There are many applications in the chemical, petrochemical and power industries, where filtration of hot gas is required to protect downstream equipment, for process separation, or to meet environmental regulations. Filtering the gas emanating from a reactor at high temperature is important, since cooling will either require a heat exchange or mixing with cold air, at an added cost.
When mixing with cold air, the dew point should be controlled to prevent condensation. Hot gas particulate filtration has been identified as a key component for the successful implementation of coalbased combined cycle power systems such as Pressurized Fluidized Bed Combustion (PFBC). The proper selection of filter media with appropriate pore size, strength and corrosion resistance enables long-term filter operation with high efficiency particle retention.
For gases with low levels of particulate contamination, filtration by trapping the particles in the depth of a porous material is satisfactory. The life of such a filter will depend on its dirt holding capacity and corresponding pressure drop. For gases with high dust loading, the operative filtration mechanism is cake filtration.