Rheinberg

This 54 MW TwinPac gas turbine CHP application at Solvay`s Rheinberg chemical plant provided efficient heat and electrical power and could also operate as a synchronous condenser to support local grid stability

Solvay’s Rheinberg plant in Germany produced a number of energy intensive chemicals including soda ash, chlorine and polyvinylchloride. The energy costs for the plant were high, with a large demand for both electrical power and process steam. To increase capacity, reduce emissions and boost efficiency, the plant’s management decided to install a new combined heat and power (CHP) gas turbine plant to take over the supply of electrical baseload and process heat.

The 54 MW plant comprised 2 x FT8 aeroderivative gas turbines each rated at 27 MW in a “Twin-Pac” arrangement. Each gas turbine had a seperate power turbine which connected to the synchronous generator via a flexible coupling and an Encased 170T SSS Clutch. The power turbines also fed Heat Recovery Steam Generators (HRSG) that replaced an old steam boiler and provided the manufacturing plant with its production steam requirements.

The aeroderivative gas turbine design was particularly well suited to this system arrangement, as they have their own starter system to bring each gas turbine up to speed. The SSS Clutch engaged when the speed of the gas turbine matched the speed to the generator and the teeth on the input shaft automatically aligned to the teeth on the output shaft.

This CHP system design was driven by availability and part load efficiency requirements. The SSS Clutches at each end of the generator permited the gas turbines to operate independently, thus providing maximum flexibility and efficiency over a wide load range working conditions, between full load (54 MW) and half load (27 MW). If the power requirements droped below half load, one of the gas turbines could be shut down, providing a fundamental advantage over other gas turbines in the 50 MW power class.

A full redundancy concept was implemented at the Solvay plant, with separate auxiliaries, ancillaries and control systems provided for each gas turbine and HRSG. As such, either gas turbine or HRSG could be shut down for maintenance or repair work while the second unit remained operational.

The system was also able to function as a synchronous condenser. In this operating mode, the generator uncoupled from the drivers and provided reactive power and inertia to the electricity grid with minimal mechanical losses.

The SSS 170T Clutches at the Rheinberg plant were seated in their own casings, mounted to the generator base frame. They were fed with oil from the generator oil system.