Coletto Creek,
Texas
The combustion of coal produces small particulates which have to be captured prior to their emission from a power station to prevent environmental damage. Historically, the equipment used for this consisted of electrostatic precipitators which use electric charges to attract and hold the particles. These devices work very well when a plant is at full load, however are less effective during start-ups and shut-downs.
Fabric filters, commonly called ‘baghouses’, provide significant advantages over electrostatic precipitators for the capture of dust and also mercury particles. These work very much like a domestic vacuum cleaner. The expelled flue gas is drawn across bags which trap the particles before the flue gas escapes. The captured matter is collected and sold as an ingredient for concrete.
Coleto Creek’s environmental performance has attracted recognition from the US Environmental Protection Agency who presented the plant with an Environmental Excellence Award in 1993. In 2006 Coleto Creek decided to further improve environmental performance by upgrading its technology to state-of-the-art particulate control, installing a baghouse, to further reduce dust emissions and prepare for future mercury emissions-related regulations.
The challenge for Coleto Creek, in constructing the new baghouse, was how to complete the installation without disrupting the operation of the plant. In addition, the existing precipitators treated flue gas upstream and the baghouse was designed to take the flue gas downstream of the air preheater. This meant all of the ductwork from the boiler had to be modified.
The solution was to construct the baghouse to the side, while the boiler was operating, then connect the new ductwork routing flue gas to the baghouse during a planned outage. The project commenced in June 2006, and was successfully completed during a scheduled outage in 2007. The baghouse has now passed all necessary regulatory performance tests and is currently meeting all of our performance expectations.