August 1, 2010

Local Warming: Helsingin Energia Uses CHP to Heat a City

SSS Clutch Co. In.

Flexible Operations

To give plant operators the operating flexibility required, ABB-Stal Utility Division used a clutch from SSS Gears Ltd. for Vuosaari B. The SSS clutch is a freewheeling clutch. When the device connected to the output shaft of the clutch is moving faster than the input side, the clutch disengages. When you apply power to the input side, however, and its speed matches or exceeds the speed of the output side, then the clutch engages (Figure 7).

7. Clutch operation. A clutch installed between the low- and intermediate-pressure turbines allows the plant to disconnect the low-pressure turbine and use that steam to produce thermal energy for district heating. When more electricity is required, the steam used for heating is redirected to the low-pressure turbine. When the low-pressure turbine reaches driveline speed, the clutch engages, adding its horsepower to the driveline to produce an additional 48 MW. Courtesy: SSS Clutch Company Inc.

The clutch was installed between the low- and intermediate-pressure turbines. When the demand for electricity is low at night, the steam can be redirected from the LP turbine and used to heat water, which is stored in a hot water accumulator for use when needed. As the steam is cut down, the clutch disengages the LP turbine from the HP/IP turbine. Then, when electricity demand rises, the steam is redirected to the LP turbine and the clutch reengages, bringing the 48-MW LP turbine back online. “The SSS clutch allows the turbine to operate as both a baseload and a peaking generator, while also providing district heating when needed,” says Lampinen.

—Contributed by SSS Clutch Co. Inc.