Carlisle SynTec, Inc
Carlisle SynTec manufactures single-ply roofing systems primarily for commercial and industrial applications. In most situations, return of boiler steam condensate is a viable and often utilized energy recovery and water conservation practice. However at Carlisle SynTec, the return and reuse of steam condensate has not been feasible due to its use of a mica coating in the manufacture of EPDM (ethylene propylene diene monomer), a type of synthetic rubber.
During the production of EPDM, steam condenses on the product, the mandrel and autoclaves interior walls. This steam condensate is not returned to the boiler due to the suspended mica particulates that render the condensate unusable. Prior attempts to remove the mica with traditional cartridge filtration had been ineffective, causing immediate boiler pump seal wear & failure, coating of internal boiler surfaces and even internal boiler component blockages. This required subsequent repairs, system downtime and parts and labor costs. No further attempts to filter the condensate were pursued.Seeing an opportunity, Carlisle Syntec requested assistance from the Illinois Sustainable Technology Center (ISTC) to investigate the feasibility of producing a steam condensate suitable for return to its boiler, saving natural gas, chemicals and water.
A condensate sample and a mica raw material sample were collected. ISTCs Laboratory Services sized the samples using a Coulter LS Particle Size Analyzer.
Sizing results indicated that the mica particles had a broad range of particle sizes (from 0.2 micron to 200 microns) which most likely would render standard bag or cartridge filtration ineffective. With this in mind, ISTC set up a portable ultrafiltration membrane unit on-site, and successfully processed a small sample batch of heated condensate.
The ultrafiltration system was thoroughly cleaned before use and water fluxes (permeate flow rates) were collected at multiple pressure points for establishment of a baseline for future reference. Over time, as the membrane system processes the condensate, membrane fouling occurs and flux rate declines which is typical and to be expected. Finding the rate at which this occurs is the reason for conducting the pilot.
The pilot system ran for 142.5 hours and processed approximately 11,970 gallons of heated condensate. The permeate flux was recorded periodically from the startup through the end of the pilot. The end was determined when the flow rate leveled and remained steady. The system was then cleaned using physical action, followed with detergents, and then clean water fluxes were recorded and compared to the initial water fluxes to determine the best cleaning methodology.The pilot conducted at Carlisle SynTec has shown ultrafiltration membrane technology to be a feasible methodology for removing its mica particulate from steam condensate making it suitable for reclamation and reuse in the boiler. Reclaiming this condensate will save water, chemicals and energy, an opportunity that Carlisle SynTec would like to further investigate with ISTCs assistance.
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