Challenge

The 8 million gallons per day (MGD) Kingston, N.Y., Water Treatment Plant has been in operation for 103 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 5-h.p. lime slurry feed pump had always been oversized for its application. For many years, water had to be continually added to the slurry solution tank of the plant’s Wallace & Tiernan A-690 volumetric feeder to keep up with the demand of the positive displacement pump. In addition, the pump required extensive and expensive maintenance. “Our slurry pump was a maintenance nightmare,” says Chief Plant Operator Bruce Mitchell. “We’d be lucky if we got three or four months service from the pump’s shaft sleeves. And those are very expensive.” The facility needed a less maintenance intensive replacement for the oversized pump and after investigating a number of different types of pumps, plant management decided a peristaltic pump would best meet the plant’s requirements and simplify the lime application process.

Solution

The existing centrifugal pump was replaced with a S26 Model Chemtube® Peristaltic Pump System (PPS) from Wallace & Tiernan.  

With the Chemtube PPS, there are no valves or seats required in the pumped fluid to foul or wear out, as with other pump types.

In addition, premium, efficient roller technology eliminates use and disposal of the lubrication fluid typical of other peristaltic pumps using a sliding-shoe design.

Results

Kingston’s continuous feed Chemtube PPS pump, equipped with mechanical variable speed drive, operates around the clock, feeding between 150 to 500 lbs. per day of lime, depending on water quality and the time of year.

• With the new pump, the lime application process is accomplished without continually adding water to the slurry solution tank.
• Also, the maintenance requirements of the Chemtube PPS are dramatically lower than with the old pump. In more than a year of 24-hour, 7-day per week service, the only maintenance performed on the new pump was replacement of the rubber feed hose after eight months of operation. “Replacing the hose was a simple procedure,”says Mitchell. “One operator accomplished the changeout in 30 minutes. And it was the first time he had ever done it.”
• The pump is 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.
• Because the h.p. requirement of the Chemtube PPS is only a fraction of the former, 5-h.p. pump, operating costs have been reduced.
• The compact design of the Chemtube PPS minimizes floor space, providing more room for service and other equipment. “The new pump’s footprint is probably a third of the old pump’s,” Mitchell says. “The lines going from the pump to the effluent mains are smaller and connections are a lot easier to take apart – the Chemtube is just much easier to handle, all the way around.”