Calgon Carbon Corporation is a publicly-traded international company based in Pittsburgh that produces materials used for industrial and commercial markets. Its flagship factory in the United States is the Big Sandy Plant in Kentucky, which produces activated carbon from bituminous coal.
In 2013, the company hired Black & Veatch to upgrade their boiler makeup water treatment system and assist in other modifications to reduce operating and maintenance costs of the plant.
Makeup water from the nearby Big Sandy River is high in calcium, magnesium, sodium, chlorides, nitrates, silica and other minerals and needs to be conditioned for efficient boiler operation. The plant's existing water-softening system was not producing the high purity water quality required to operate the boilers efficiently. The plant was operating at approximately 20 percent blowdown of the boiler water each day. These high blowdown rates and the associated excessive water treatment costs and reduced thermal efficiency were resulting in excessive costs to the company.
Additionally, the river water quality caused problems with the plant's flue gas scrubber system. The scrubbers remove sulfur dioxide and other contaminants from flue gas. The high mineral content of the river water caused scaling on the equipment, reducing its effectiveness and requiring costly routine maintenance.
Calgon turned to Black & Veatch, whose experts devised a solution that not only significantly improved boiler efficiency and water treatment operating costs but also solved the scrubber issue.
The fix had two parts. First, a new water treatment system consisting of an ultrafiltration unit and a reverse osmosis unit was designed to improve boiler makeup water quality. Three of these duel-unit systems were installed, each capable of producing 100 gallons per minute (GPM) of purified water. Two units would run parallel — 200 GPM total — with a third available as a spare.
Space for the new system in the existing plant was inadequate. The new treatment system is housed in a prefabricated building outside the plant, next to the existing water treatment system. Black & Veatch worked with plumbing contractors to design and install the interconnections without affecting plant operation or impeding existing equipment.
The existing water treatment system didn't go to waste. While the water quality was not adequate to work efficiently in the boilers, it made a significant improvement in scrubber operation. Black & Veatch designed a system that redirected the existing treatment equipment effluent water to the scrubbers.
Once online, water from the new boiler makeup treatment system reduced overall water consumption by the boilers from 20 percent to approximately 2 percent per day.