AirProtekt removes carbon-fibre plant contaminants

AirProtekt has installed and commissioned a combined system to remove oxides of nitrogen and other gaseous contaminants from SGL Carbon Fibres' manufacturing facility in Muir of Ord, Scotland.

SGL Carbon Fibres is a subsidiary of German-based SGL Group and the Scottish manufacturing site produces carbon fibre for use in a variety of engineering applications.

The site has upgraded the production capacity of its facility with the addition of two new production lines.

To assist in handling the additional emissions, including fugitives from the upgraded facility, AirProtekt was selected to supply a third Regenerative Thermal Oxidation (RTO) system at the site in combination with a new Selective Catalytic Reduction (SCR) system.

The principal purpose of the new combined system is to treat and remove pollutants such as oxides of nitrogen and hydrogen cyanide.

The SGL carbon-fibre manufacturing plant uses Polyacrylonitrile as a raw material in the form of long lengths (tows) of carbon fibre.

The tows are heated by passing through a series of electric or gas ovens and furnaces.

The first stage of heating in ovens to 250C in the presence of air produces oxidised Polyacrylonitrile or Panox, which is sold as an oxidised fibre product.

The Panox can be further heated within low temperature and high temperature furnaces to 1,500C in the absence of air to produce carbon fibres for use in various engineering applications.

The chemical reactions during the heating process generate exhaust gases of oxides of nitrogen, hydrogen cyanide, ammonia, carbon dioxide, carbon monoxide and volatile organic compounds.

The exhaust gases are extracted using RTO systems that reduce the levels of the contaminants prior to discharge through stacks, which are the main point sources of emissions from the carbon-fibre manufacturing process.

The combined RTO and SCR system was developed, engineered and installed by AirProtekt and Lufttechnik Bayreuth (LTB) to free capacity on one of the older RTO systems.

This improved the capture of fugitive gases from one of the manufacturing units and helped to address overall control of the release of odorous emissions from the Muir of Ord facility.

AirProtekt and LTB's engineering team tailored the combined RTO and SCR system to comply with SGL Carbon Fibres' specific emission regulation requirements.

The solution was required to allow the Muir of Ord facility to comply with the emission-limit values specified in its operating permit granted by the local environmental authority.

AirProtekt offered the 4,500 tonnes per year Scottish carbon-fibre manufacturing facility a complete package solution that involved system design, equipment supply, installation and commissioning, supported by an after-sales service team.

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