Environment
Catalytic filtration in the glass industry Martin Schroeter* explains how the versatility of catalytic filtration can become the recognised technology for stack emissions control within the glass industry.
T
oday, catalytic filtration is a widely accepted technology for control of stack emissions in the glass industry. Both in Europe and the USA, it holds a status of Best Available Control Technology (BAT / BACT) and became the preferred solution for control of NOx, SO2 and PM emission in Asia. While the implementation of the catalytic filtration technology in the glass industry has been installed due to a variety of drivers across different geographies, this paper summarises the versatility of the technology to address those drivers and inspire upgrading solutions.
Versatility of the technology One of the major characteristics of the catalytic filtration technology is its adaptability to accommodate different regulatory requirements. The track record of the catalytic filtration technology began in Europe in the late 2000’s as an alternative solution to add NOx removal efficiency up to 95% with negligible ammonia slip. This was a major concern for regenerative furnaces during flow reversal.
Four years later, the catalytic filtration technology was adopted for the glass industry in the USA, while it took further three years for the first catalytic filtration system start-up in Asia. At the heart of the technology is a filter candle made of ceramic fibres, which allows operation at elevated temperature of up to 900°C (1,650°F). The dust separation follows the principles of surface filtration on a conditioned layer, the “filter cake”. While dust removal is achieved with back pulse air, only part of the filter cake is detached and removed to the hopper section of the filter house. Since the ceramic filter does not expand during back pulsing, a residual dust cake will always remain on the filter. The residual dust cake prevents any constituent of the particulate matter to penetrate into the filter wall and thus makes the filter wall the ideal location to place a finely dispersed DeNOx catalyst as it will be entirely protected from particulate blinding. In combination with dry sorbent injection, typically using hydrated lime
as the sorbent, the catalytic filter is now capable to control both filterable and condensable particulate matter, NOx and acid gas precursors, like SO2, SO3, HCl or HF, together with metals and HAPs falling in the category of acid type components. While the catalytic filtration technology provides a high removal efficiency for all targeted emissions, geographies with moderate regulatory requirements may still consider catalytic filtration as a forward-thinking solution, which will still meet present regulations and be prepared for future requirements. This technology can also be used in combination with pre-existing emission control equipment -- adding emissions reduction capabilities by installing a partial flow treatment with catalytic filtration provides clients with a CAPEXefficient solution. At the other end of the spectrum, combination with traditional technology, like an SCR DeNOx slip reactor downstream of the catalytic filter system, can provide highest removal efficiencies Continued>>
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� Different regulatory requirements (removal efficiency/system availability) in different geographies.
49 Glass International July/August 2021
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