Thinking about filtration

Ceramic filtration, both catalytic (UCF) and non-catalytic (UTF), is now a widely accepted solution for the control of stack emissions. The technology initially built-up extensive references throughout the glass industry, and has proven its versatility in meeting a variety of technical and regulatory drivers. Ceramic filter technologies are often considered a Best Available Control Technology (BAT/BACT/BARCT/RACT) in certain industries across North America, Europe and Asia.

Today, ceramic filtration technology has gained acceptance in a variety of industries. Ceramic filters are now a proven alternative to traditional technologies such as baghouses, ESPs and SCR systems to achieve high levels of NOx, SO₂ and/or PM reduction at high temperatures, and are becoming increasingly cost-effective due to their high performance and lower operating costs when considered across the lifetime of the system.

The technology

Ceramic filtration technology originated from the desire to create a system that combined the efficiency of a fabric filter (with regard to PM removal), with the energy efficiency of an electrostatic precipitator (ESP). Furthermore, in achieving high levels of NOx reduction, decades of experience in the coal fired power industry has proven the longevity of Selective Catalytic Reduction (SCR) technology catalyst life in a so-called tail end arrangement downstream of a fabric filter. The major disadvantage when combining a baghouse with an SCR, is the different flue gas temperatures required by both technologies. While most baghouses have a max temperature of 200 – 240°C (400 – 450°F), it is necessary to reheat the flue gas post baghouse to the desired operation temperature of the catalyst as shown in Figure 1, which is a major disadvantage, especially in times of increasing efforts to limit CO₂ emissions.

Ceramic filtration technology negates the need for costly reheating requirements, with the technology able to operate at temperatures of up to 900°C (1600°F). This offers an advantage in combination with a waste heat recovery system; when installed downstream ceramic filters, heat exchangers for WHR have higher efficiency and lower operating costs.

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