Simplifying Lime Feed, Lowering Costs

Challenge

The 8-million-gal-per-day (mgd) Kingston, N.Y., Water Treatment Plant (WTP) has been in operation for more than 100 years. Although a number of improvements have been made to the pressure filter facility over the years, it operates essentially as it was designed and today provides drinking water for 24,000 Kingston Water Department customers. Treatment consists of chlorine disinfection, direct-in-line filtration with alum coagulation and corrosion control through the addition of lime.

The plant needed a less maintenance-intensive replacement for its oversized 5-hp lime slurry feed pump. Plant operators used to have to continually add water to the volumetric feeder’s slurry solution tank to keep up with the positive displacement pump’s demand. Additionally, operators also had to replace the pump’s shaft sleeves every three or four months, which proved expensive.

The Kingston plant needed a less maintenance-intensive
replacement for its oversized 5-hp lime slurry feed pump.

Solution

In 2001, Kingston replaced its existing centrifugal pump with a continuous feed Chemtube peristaltic pump system (PPS) from Siemens Water Technologies. In 2005, the plant installed a second PPS. Both are elevated on pedestals to facilitate maintenance.

Premium, efficient roller technology eliminates use and disposal of the lubrication fluid typical of other peristaltic pumps that use a sliding-shoe design. Unlike with other pump types, the pumped fluid does not require any valves, seats or seals that can foul or wear out.

In addition, the pumps are equipped with a leak detector to provide early indication of hose failure. A float-type sensor located at the lowest point of the pump housing immediately detects the smallest of leaks and initiates alarm contact.

Simplicity and versatility of design makes the Chemtube PPS ideal for several demanding municipal and industrial applications.

Results

Kingston’s continuous feed Chemtube PPS pumps, equipped with mechanical variable speed drive, operate 24/7. The new pumps consume less energy and require significantly less maintenance than their predecessor. Operating costs have been greatly reduced, as the pumps require only a fraction of the horsepower that the former slurry pump required.

Kingston replaced its centrifugal pump with a
continuous feed peristaltic pump system.

The Chemtube pumps feed between 150 to 500 lb of lime per day, depending on water quality and the time of year. In more than a year of constant service, operators only replaced the pumps’ hose after eight months of operation. Replacing the hose was fairly simple, according to Kingston Plant Supervisor Debra Sheeley. One operator was able to change the hose in less than 30 minutes—and that was his first changeout.

Most Chemtube PPS models, such as the two at the Kingston WTP, use a direct coupled, right-angled gearbox to provide the smallest footprint possible. This compact design minimizes floor space and allows more room for service and other equipment.

“The new pumps are only one-third the size of the old pump,” Sheeley says. “The lines going from the pumps to the effluent mains are smaller, and connections are a lot easier to take apart. The Chemtube PPS is much easier to handle, all the way around.”

Manor M. Parikh is global product manager for liquid feed technologies at Siemens Water Technologies, and is located in Vineland, N.J., USA. He can be reached at 856-507-4087 or at manor.parikh@siemens.com.

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