Electric Auxiliary Boilers Reduce Cold Startup Time of Combined Cycle Gas Turbines

Today, combined cycle gas turbine (CCGT) plants play a critical role in providing power grids with additional electricity during peak periods of high demand. By harnessing the energy from both combustion and steam turbines. CCGT plants use less fuel overall and can run longer than traditional "peaker` plants to produce cheaper electricity on demand.

Depending on the condition of the region`s electrical grid. CCGT plants may be called upon to operate many hours a day. several times a week, or only a few hours per year, depending on the condition of the region`s electrical grid. Regardless of their cycle frequency, however, these peaker plants must be particularly adept at quickly transitioning between their on and off status.

One of the challenges that CCGT plants face in this regard is starting their steam turbines quickly after being offline. In a combined cycle power plant, a gas turbine initially generates electricity. The waste heat from the gas turbines is then captured via a Heat Recovery Steam Generator (HRSG), which produces pressurized steam that goes to the steam turbine, enabling the power plant to generate additional electric power.

In order to be ready to provide energy as quickly as possible, CCGT plants use auxiliary boilers to reduce the cold startup time of their steam turbines, which can save as much as 30 minutes per cycle. The boilers also play a critical role in maintaining the readiness of condensers whose function is to turn the steam recovered from the turbines back to water.

"You have to generate the steam to start the turbine turning and that is one of the major uses of auxiliary boilers." said Robert Presser, Vice President of Acme Engineering, a manufacturer of industrial and commercial boilers with operations in the U.S.. Canada, and Europe. "When you need an auxiliary boiler to start the turbine, you need a lot of power and you need it fast."
Managing an `on and off again9 relationship

In one example, Acme Engineering was asked to provide a 3-megawatt conventional electric boiler system for Goreway Power Station in Brampton, Ontario. The 875 MW natural gas-fueled combined cycle plant provides electricity to Ontario`s power grid on a 24/7.