Reducing Boiler Feedwater Costs with Reverse Osmosis, 1992 Engineering Conference Proceedings

The Fernandina Beach Mill of Container Corporation of America was experiencing a shortage of boiler feedwater makeup capacity. This was due largely to the high mineral content of the well water supply which necessitated a daily regeneration cycle for the demineralizer units. The resin and chemical costs associated with this short regeneration schedule were also high.

After evaluating commercially available treatment technologies, reverse osmosis (RO) appeared to have the greatest acceptance in municipal water treatment and a number of successful installations to evaluate. Based on this information, a pilot plant was installed on the mill site. After ten (10) months of operation and numerous abuses, the unit produced the expected water quality and proved its durability for industrial use.

A conservative design approach was taken in all phases of the project due to the criticality of the makeup water supply. Redundant control systems, high quality materials for piping and mechanical systems, and low membrane flux rates were used to assure reliability and longevity.

After a thorough pre-startup check of the control systems and an extensive flushing and cleaning of the piping systems, the system was brought up to design performance and put on-line in a matter of days.

After several months of operation, system performance began to decline. Numerous tests and cleanings of the system had little effect. During a scheduled shutdown period, sand was found in the system downstream of the cartridge filters. This sand had become imbedded in the first elements on each RO skid. This condition was caused by poor sealing of the filter cartridges in the filter housing. Upon installing a new design filter cartridge and cleaning the elements, performance increased immediately and steadily improved over the next six (6) months.

After two and a half years of operation, the polyamide thin film composite RO system has proven to be an economical, reliable, and efficient pretreatment system for demineralizers.