High-rise, water/wastewater heat exchange saves 30% on energy costs
While some process industries only got hip to sustainability recently, water/wastewater was green from the beginning. It’s always been concerned with treating drinking water for consumption, and cleaning wastewater for release as effluent. Lately, however, the water/wastewater industry is finding even more ways to be sustainable, such as optimizing generators in hydroelectric applications or otherwise limiting energy use.
“Sustainability is also about combining stewardship with efficiency, and understanding how the outcomes involved in providing them do well by people and the planet,” says Greg Graves, VP of sales and marketing at Revere Control Systems, a system integrator in Birmingham, Ala., which was acquired by SJE close to a year ago, and is a certified member of the Control System Integrators Association. “Our original owner, Bob Adams, advocated stewardship, even though the demands on most water/wastewater applications haven’t changed, other than needing more cybersecurity protections.”
For instance, Revere has partnered with G.A. Fleet Associates for 35 years to design and implement water/wastewater and related building systems for many high-rises and other structures in New York City, including the Freedom Tower, Hudson Yards and the 9/11 Memorial. About 17 years ago, Revere and GA Fleet developed their Fleetway specialized, flexible, hardware and software control platform for managing pumps, tanks, water distribution, and pressure and water hammer forces in those often-huge structures.
Starting out as a simple sewer ejector system—basically a lift station control for wastewater—Fleetway has evolved with Revere’s software and circuit designs into a control system with customizable panels, HMIs and networking with BACnet and EtherNet/IP protocols, which serve tank-fill systems, booster processes, cooling towers, standalone tanks, HVAC and other applications. The platform’s flexibility and scalability makes it field-configurable, and enables it integrate seamlessly with building management systems (BMS). Likewise, Fleetway can handle unexpected challenges, such as missing components, or last-minute design changes, as well as support hot swapping of live changes while its system is powered. In addition, users can read, assign inputs, adjust hardware connections, and even redefine system behavior with Fleetway’s touchscreen interface without needing a custom PLC or programming.
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To comply with recent New York’s municipal regulations mandating reduced natural gas consumption, they’ve also spent the past five or six years collaborating on using Fleetway to recover leftover heat from outgoing, 98.6 °F wastewater, and employ it to indirectly heat incoming, clean, typically 60° F water. This process runs the wastewater through a heat exchanger, which gets the clean water 90% of the way to the 90 °F to 120 °F level it needs to reach, which saves about 30% of the energy that’s usually required to heat it, according to Graves.
“Every building could have multiple Fleetway applications, including one for its sewer system, another for its tanks and level control, and another to manage the water columns in between,” explains Graves. “Fleetway is an industrial platform that can save energy in costly high-rise environments and elsewhere. Heat exchangers are already everywhere, but we haven’t seen them used in the water/wastewater streams of major buildings yet, which is what we’re trying to do.”
