Gas/electric switching saves up to 8 percent on energy
At Veyance Technologies' 1-million-sq-ft plant in Lincoln, Neb., where rubber power-transmission products are made, three outdated gas- and oil-fired boilers used for both production and climate control were in need of replacement. "We were running on much larger boilers from the 1960s, and we were looking to increase energy efficiency and add automation," plant engineering manager John Leach said. "We've been in Lincoln since the 1940s, and a lot of our equipment is from the '50s and '60s."
Today, Veyance operates with a boiler system that includes two Vapor Power Circulatic gas boilers (model TG-5907-SHK-300) with rated capacities of 300 bhp at 250-psig saturated steam and a Vapor Power HSI Electric boiler (model BBJ-600-250) with a rated capacity of 600 bhp at 250 psi. These are integrated with one natural-gas-burning "legacy" boiler from 1965. A single Vapor Power interface runs the highly automated system.
Since the installation of the Vapor Power boilers in late 2008/early 2009, Veyance has realized 5-percent to 8-percent savings on energy costs and trimmed its boiler-maintenance staff from four operators to two. Resource savings also came through elimination of fuel-oil inventory and the speed of system startup, which took one day, Leach said.
"I've been involved in a lot of boiler startups, and they are normally two to three days," Leach said. "There are a lot of resources that go into a startup, and we didn't have to dedicate those resources for several days. Plus, we were able to start saving energy two days earlier."
The system allows the switching of fuels as prices fluctuate.
"The electric boiler gives us an alternate fuel," Leach explained. "A few years ago, the price of natural gas was really high, and the price of oil is still high. Electricity prices vary, depending upon where you are located. If you are in New York City, for instance, they are really high. We have a pricing structure here in Nebraska that gives us an opportunity to take advantage of electricity prices."
In addition to the flexibility to negotiate shorter-term contracts with fuel providers, Veyance can shed load at times of peak electrical usage and increase load at times of lower electrical usage, which yields a more favorable rate on a day-to-day basis. Also, electricity is more expensive than gas during summer and vice versa. Leach said taking advantage of these fluctuations by starting or stopping the electric boiler is behind much of the energy-cost savings.
If either fuel source becomes unavailable, the plant will have immediate backup steam.
"We chose this configuration because we felt it would give us the best operational flexibility," Leach said. "If we have a change in our processes that requires more steam, we can add that quickly. On the other hand, I'm able to keep a minimum amount of boilers operating. These things (automatically) shut down or turn down based on load."
Information and photographs courtesy of Vapor Power International.