SubscribeApplication stories from throughout the world illustrate the diversity of valve automation projects in the water industries that are facilitated by Rotork's valve actuation services.
Case Study 1
Warminster uses IQs, AQs and Pakscan to operate at peak efficiency
Bob Elliott, Rotork’s correspondent in the USA, reports:
The Warminster Municipal Authority Wastewater Treatment Plant, located in scenic Bucks County, Pennsylvania, operates with the efficiency and precision of a fine Swiss watch. It serves a population of about 66,000 and is designed to treat over eight million gallons of wastewater a day from residential, commercial, and industrial users.
George Pfeiffer, Sewer System Superintendent, Warminster Municipal Authority, said, “Automation and teamwork keep things running smoothly around here. We have made a commitment to invest in our employees, have reliable equipment, do most of our own maintenance, and use automation where it makes economic sense.”
That simple formula has resulted in good things for Warminster’s customers, too. They pay one of the lowest rates in the area.
Caption: In 1999, employees of the facility, themselves, installed Rotork IQ actuators on telescopic valves which regulate the flow of wastewater in and out of the primary settling tanks. The actuators are linked by a Pakscan two-wire loop communication system to the facility’s PLC.
Before that, all the valves were manually operated every four hours. Now, they operate every half-hour automatically, enhancing process efficiency.
The Biological Process
The plant was originally built in 1959 and has been upgraded several times, most recently in 2001. It now employs a totally biological A2/O process for wastewater treatment. The main steps in the process include: screening, grit removal and primary settling, A2/O processing and treatment, final clarification, and disinfection by intense ultraviolet light.
According to an engineering consulting firm hired by Warminster, the totally biological A2/O process has shown that it can accomplish BOD and nutrient removal at a much higher process efficiency than conventional activated sludge treatment.
The plant discharges its treated water into Little Neshanamny Creek, which is part of the Delaware River system. By maintaining its highly efficient operation, the Warminster facility is doing its part to help make Little Neshanamny Creek cleaner.
Pfeiffer said, “Keeping the environment clean is a top priority for us. We process wastewater biologically with no chemicals, and we completely remove nitrogen. Specifically, our process removes ammonia, nitrates, nitrites, and phosphorus. After our last major upgrade in 2001, we have virtually eliminated suspended solid overflows after heavy rain storms.”
Pfeiffer said, “Because the process is totally dependent on biological treatment, rather than chemical treatment, it is necessary that we monitor and carefully regulate every step of the process. It’s important to have a dedicated staff of professionals who are well-trained and thoroughly understand their duties. We’ve also invested in cost-effective automation equipment that’s dependable and able to perform well around the clock.”
Caption: Warminster Municipal Authority has a staff of 29 employees who work as a team to keep theplant running at peak efficiency. From left, George Pfeiffer, Sewer System Superintendent;Henry McKillip, Lab Technician; and Stephen Sweder, Operator.
Valve Automation Trial
In 1999, Pfeiffer started a SCADA pilot project to see if automated valves would help improve productivity and performance on the primary settling tanks. Previously, a total of 16 telescopic valves were manually operated and needed to be drawn down every four hours, 365 days a year.
Pfeiffer called upon Edwin Elliot and Company, Lafayette Hill, PA, to assist them with the project. After a careful analysis of appropriate technology, the Authority decided to install 16 Rotork IQ electric actuators, a Pakscan two-wire loop, and a Pakscan IIS masterstation for local control at the primary settling tank site.
“We did all the wiring and installed the valves, stems, and actuators in-house,” Pfeiffer said. “It was easy. The Pakscan two-wire daisy-chain system was simple to hook up. We saved a tremendous amount of money by doing the work ourselves,” he added.
“From day one the primary tank settling process became extremely more efficient. It was ten-fold better than doing it by hand. Now, time and position of the valves are controlled by PLC. We are operating the valves every half-hour now, instead of every four hours as we did when we were doing it manually. More frequent operation, lets us control the process better,” he noted.
Expanding the Concept
Because the automated valves worked so well at the primary settling tanks, the Authority decided to apply the same concept throughout the plant. They have Rotork actuators and Pakscan communication systems on all the sludge-handling processes, digesters, and centrifuge.
“All in all,” Pfeiffer commented, “we have a total of more than 50 Rotork IQ and AQ actuators with all of them tied to the Pakscan system. The programming is interfaced with our PLC, so it’s easy to tell each actuator what to do and when to do it. Each valve actuator has its own address, so we have maximum control.”
Warminster takes pride in doing as much work in-house as possible. They do approximately 98% of all maintenance throughout the plant by themselves.
Pfeiffer said, “The reliability of the Rotork actuators and Pakscan system has been excellent. I couldn’t ask for anything better.”
Caption: From left, Operators Timothy Pattison and John Dee stand near Rotork AQ actuators, which operate valves for the digester phase of the wastewater treatment process.
Case Study 2
A helping hand for migrating salmon
Frank Koopmans at Rotork Holland notes:
The fish stairs at Hagestein on the River Lek, a tributary of the Rhine, is one of an increasing number that have been built to encourage the return of migrating fish to the main rivers of the Netherlands. The dramatic improvement in water cleanliness brought about by the country’s successful environmental policies has enabled salmon to return to old spawning grounds, although their progress can be hampered by man-made barrages and sluices.
Rijkswaterstaat, the responsible authority, is therefore building specially designed fish passages, or stairs, around the obstructions, controlled by adjacent sluice gates that regulate the river flow under changing ambient conditions. The use of Rotork IQ electric actuators facilitates automatic operation of the sluice gates in response to signals from level sensors.
Case Study 3
New actuators secure third century of operation for Australian water valve
Spencer Jenner from Rotork Melbourne reports:
A valve that was installed in 1895 has been retrofitted with Rotork IQ actuators during an upgrade programme on a dam at Adelaide in South Australia. The 975mm diameter double door stop valve was installed on the pipeline from the Happy Valley dam, built in 1890’s to provide the increasing population of Adelaide with a reliable water source.
Caption: The Happy Valley double door valve during it’s original installation.
In 2003, the South Australian Water Corporation – a long-standing customer of Rotork Australia – began a 20million dollar modernisation project on the dam to address safety issues related to flooding and earthquakes, since a large population now resides downstream of the dam. SA Water wished to use the old valve as a scour valve to draw down the reservoir level should flooding become imminent.
Before the work could start, the valve’s internal condition was assessed by SA Water’s diving team, who had to swim for over 30 metres down the 915mm diameter pipeline in order to carry out the inspection. Once thevalve’s condition was confirmed as good, SA Water’s valve expert Michael Stasiuk designed new adaptation to enable two Rotork IQ actuators and gearboxes to be fitted to the valve, in-situ in the reservoir outlet tower, 20 metres below water level.
The completion of the retrofit work now enables the valve to be controlled remotely – securing its usefulness into the third century of operation.
Case Study 4
Filter upgrade is first for Pakscan and modulating pneumatic actuators
Mike Heuseveldt from Rotork Fluid System in Rochester USA reports on the innovative use of the Pakscan two-wire control system to operate modulating pneumatic actuators.
The Clinton Water Treatment Plant in Illinois has been recently modernised and expanded, improving filtration quality and increasing output.
As part of the filter plant upgrade Rotork supplied P and SP range pneumatic actuators, in various combinations of double-acting and spring-return for isolating and modulating duties with stay-put or failsafe closed operation on loss of power. The twenty-nine actuators, which are operating butterfly valves on filter clarified and wash water circuits and plug valves on filter sludge circuits, are all controlled by a Pakscan two-wire digital control system.
Caption: Rotork pneumatic actuators on filter-to-waste drain valves.
The on/off pneumatic actuators were fitted with Rotork’s standard remote control and indication package, including the Pakscan interface card, to energise open and close solenoid valves. However, the modulating actuators demanded an innovative, customised package to facilitate Pakscan connectivity. This was achieved by equipping a Pakscan General Purpose Field Unit with an electro-pneumatic transducer to send a 3-15 psi signal to the actuator’s pneumatic positioner in response to commands from the Pakscan loop.
This is the first time that Pakscan has been used for modulating pneumatic actuation, providing further evidence of how the benefits of Rotork’s predominance in electric actuation control systems can be translated into the operation of Fluid System equipment to meet the increasingly sophisticated expectations of plant operators.