Backup Power for Pumping Systems

There are several steps that water utilities can and should take in this regard.

The first three strategies involve energy efficiency in general for pumps:

The first is to ensure that they have the most energy-efficient pumps possible.
The second is to conduct energy audits of the pumping system.
The third is to introduce other energy efficiency strategies into the utility’s pumping system, which might be the result of the energy audit’s findings.

When it comes to keeping water utilities operating, pumps are considered to be the highest priority. So, what does it take to keep the pumps running, especially if a water utility suffers a power outage from the local electric grid? There are several steps that water utilities can and should take in this regard. The first three strategies involve energy efficiency in general for pumps:

The first is to ensure that they have the most energy-efficient pumps possible.
The second is to conduct energy audits of the pumping system.
The third is to introduce other energy efficiency strategies into the utility’s pumping system, which might be the result of the energy audit’s findings.

[text_ad] These three steps are important. If and when power does go out, backup power sources (such as generators) won’t need to be as large or work as hard to keep the pumps running during the outage if you have energy-efficient pumps to begin with, as well as other energy efficiency strategies in place that reduce the need for excess amounts of energy. This article will focus on the first strategy, looking at energy efficiency for pumps. Efficient Pumps According to “Energy Efficiency and Water Pumping Fact Sheet,” published by the Water Research Foundation (WRF), 80% of the energy used in water treatment and distribution is used to pump water. Given the large amounts of energy that are required by the pumps to lift and move water, and because energy costs are often the second highest cost in a water utility’s operating budget, the proper selection of pumps, motors, and controls is critical in order to ensure an efficient system and be able to control costs. According to “Improving Pumping System Performance: A Sourcebook for Industry,” published by the US Department of Energy (DOE), in order to ensure that you select the most efficient pumps, it is important to know the rates of flow and pressure in the pumping system. There are many combinations of pumps and components, and the challenge is to be able to identify the most cost-effective and energy-efficient mix in order to be able to match the design of the pumping system. When evaluating pumping systems for ways to improve efficiency and reduce costs, the DOE recommends that water utilities should identify indicators of inefficient pump system operations. These indicators include pumps with high maintenance requirements, oversized pumps that operate in a throttled position, badly worn pumps, and noisy pumps or valves. As part of pump system improvement, the DOE recommends that water utilities should evaluate the pump motor. Motors control pump speed and are directly tied to the efficiency of the pumping system. If motors are operated for long periods of time (more than 50% of the time),then motor efficiency increases. They are most efficient when running 75% of the time. The DOE recommends that water utilities should develop plans to upgrade existing motors with premium efficiency models, since those motors can provide up to 10% more efficiency compared to standard models. [text_ad use_post='27033'] In addition, according to the WRF, the installation of variable frequency drives (VFDs) is one of the easiest energy reduction improvements a water utility can implement. VFDs are electronic controllers that adjust the rotational speed of an electric motor (such as a pump motor) by controlling the frequency or voltage of the electric power supplied to the motor. VFDs should be considered when a pump is oversized, or when a throttling valve is used in pump operations. The WRF estimates that the use of VFDs can reduce energy by as much as 50%, because VFDs match the motor speed to the specific energy demanded. As a result, energy is conserved, because the drive operates at lower speeds when appropriate. One manufacturer offering energy-efficient pumps is Flygt, a division of Xylem. Flygt offers “N-Technology Pumps,” which are designed for self-cleaning. “They have backswept leading edges, so, rather than having horizontal leading edges, where material such as rags and other trash can get caught on the impeller, our pumps have a horizontal backswept leading edge, so debris gets cleared off the impeller each time it rotates,” says Lisa Riles, North America municipal transport marketing and business development manager. “This eliminates clogging. If you are pumping clean water, efficiency will usually be level. However, if you are pumping wastewater, there will be a decrease in efficiency when you have rags and other debris clogging it.” Flygt guarantees a 25% energy savings on its N-Technology pumps compared to standard pumps. Flygt also offers an Experior solution, called SmartRun, which includes the N-Technology (the self-cleaning function that provides more efficiency), as well as VFD technology. “Each time the pump comes on, an intelligent control system looks at the last time it was on, how long it was operating, what frequency it was operating on, and then adjusts the frequency in order to minimize energy usage,” says Riles. “This provides an additional 25% energy savings over the N-Technology pump alone, for a total of up to 50% energy savings.” As noted, VFDs are used to save energy and improve performance. However, many wastewater pump stations experience problems with clogging, due to the fact that the parameters in the VFD are not set correctly. Flygt’s SmartRun intelligent control combines the functionality of VFD with a simple interface. A number of key functions for wastewater pumping are pre-programmed, and parameters are pre-set. The control unit provides the intelligence to capitalize on the full benefits of VFD pumping. The SmartRun includes an energy minimizer function that typically reduces energy consumption by 30% compared to conventional on/off systems. One customer happy with the Flygt solution is Bradley Zellers, town manager and wastewater superintendent for Winamac, Indiana. Zellers was approached by Flygt in 2013 to conduct a study on one of the utility’s lift stations. “We were having issues with flushable rags getting stuck in our pumps,” he says. “We were pulling pumps a couple of times a week to unclog them.” Flygt installed an Experior pump in April 2014. “Since that time, we haven’t had to pull it even once,” he says. “We are also set up with a SmartRun VFD, and our electric consumption is one-third to one-half less than before.”

These three steps are important. If and when power does go out, backup power sources (such as generators) won’t need to be as large or work as hard to keep the pumps running during the outage if you have energy-efficient pumps to begin with, as well as other energy efficiency strategies in place that reduce the need for excess amounts of energy.

This article will focus on the first strategy, looking at energy efficiency for pumps.

Efficient Pumps
According to “Energy Efficiency and Water Pumping Fact Sheet,” published by the Water Research Foundation (WRF), 80% of the energy used in water treatment and distribution is used to pump water. Given the large amounts of energy that are required by the pumps to lift and move water, and because energy costs are often the second highest cost in a water utility’s operating budget, the proper selection of pumps, motors, and controls is critical in order to ensure an efficient system and be able to control costs.

According to “Improving Pumping System Performance: A Sourcebook for Industry,” published by the US Department of Energy (DOE), in order to ensure that you select the most efficient pumps, it is important to know the rates of flow and pressure in the pumping system. There are many combinations of pumps and components, and the challenge is to be able to identify the most cost-effective and energy-efficient mix in order to be able to match the design of the pumping system.

When evaluating pumping systems for ways to improve efficiency and reduce costs, the DOE recommends that water utilities should identify indicators of inefficient pump system operations. These indicators include pumps with high maintenance requirements, oversized pumps that operate in a throttled position, badly worn pumps, and noisy pumps or valves.

As part of pump system improvement, the DOE recommends that water utilities should evaluate the pump motor. Motors control pump speed and are directly tied to the efficiency of the pumping system. If motors are operated for long periods of time (more than 50% of the time),then motor efficiency increases. They are most efficient when running 75% of the time. The DOE recommends that water utilities should develop plans to upgrade existing motors with premium efficiency models, since those motors can provide up to 10% more efficiency compared to standard models.

NOTHING FOUND

In addition, according to the WRF, the installation of variable frequency drives (VFDs) is one of the easiest energy reduction improvements a water utility can implement. VFDs are electronic controllers that adjust the rotational speed of an electric motor (such as a pump motor) by controlling the frequency or voltage of the electric power supplied to the motor. VFDs should be considered when a pump is oversized, or when a throttling valve is used in pump operations. The WRF estimates that the use of VFDs can reduce energy by as much as 50%, because VFDs match the motor speed to the specific energy demanded. As a result, energy is conserved, because the drive operates at lower speeds when appropriate.

One manufacturer offering energy-efficient pumps is Flygt, a division of Xylem. Flygt offers “N-Technology Pumps,” which are designed for self-cleaning. “They have backswept leading edges, so, rather than having horizontal leading edges, where material such as rags and other trash can get caught on the impeller, our pumps have a horizontal backswept leading edge, so debris gets cleared off the impeller each time it rotates,” says Lisa Riles, North America municipal transport marketing and business development manager. “This eliminates clogging. If you are pumping clean water, efficiency will usually be level. However, if you are pumping wastewater, there will be a decrease in efficiency when you have rags and other debris clogging it.” Flygt guarantees a 25% energy savings on its N-Technology pumps compared to standard pumps.

Flygt also offers an Experior solution, called SmartRun, which includes the N-Technology (the self-cleaning function that provides more efficiency), as well as VFD technology. “Each time the pump comes on, an intelligent control system looks at the last time it was on, how long it was operating, what frequency it was operating on, and then adjusts the frequency in order to minimize energy usage,” says Riles. “This provides an additional 25% energy savings over the N-Technology pump alone, for a total of up to 50% energy savings.”

As noted, VFDs are used to save energy and improve performance. However, many wastewater pump stations experience problems with clogging, due to the fact that the parameters in the VFD are not set correctly. Flygt’s SmartRun intelligent control combines the functionality of VFD with a simple interface. A number of key functions for wastewater pumping are pre-programmed, and parameters are pre-set. The control unit provides the intelligence to capitalize on the full benefits of VFD pumping. The SmartRun includes an energy minimizer function that typically reduces energy consumption by 30% compared to conventional on/off systems.

One customer happy with the Flygt solution is Bradley Zellers, town manager and wastewater superintendent for Winamac, Indiana. Zellers was approached by Flygt in 2013 to conduct a study on one of the utility’s lift stations. “We were having issues with flushable rags getting stuck in our pumps,” he says. “We were pulling pumps a couple of times a week to unclog them.” Flygt installed an Experior pump in April 2014. “Since that time, we haven’t had to pull it even once,” he says. “We are also set up with a SmartRun VFD, and our electric consumption is one-third to one-half less than before.”