Swedish valve manufacturer SOMAS produces the triple-eccentric control dampers that are installed on the Siemens gas turbine in the new LEAG power plant. The valves are used here as blow-off and cooling air dampers.
In partnership with Siemens Energy, energy supplier LEAG has built a new turnkey gas-fired power plant in Leipheim, Bavaria. At its center is a Siemens SGT5-4000F gas turbine. At the request of the transmission system operator Amprion, the power plant will serve to ensure grid stability in the event of an emergency. This is intended to ensure a reliable power supply.
With an output of up to 300 megawatts in just 30 minutes, the SGT5-4000F generates electricity for the entire region. To ensure smooth operation, blow-off valves and control valves for the cooling air are required inside the turbine, which SOMAS provides with its triple-eccentric control dampers.
Triple eccentric control dampers in use
In a certain speed range, the aerodynamic load on the axial compressor can lead to so-called compressor pumping. To prevent this, air is blown off at certain points of the compressor before the pump-critical speed range is reached, whereby the SOMAS dampers are used. The valves are located in the blow-off lines provided for this purpose, which lead into the exhaust gas duct behind the gas turbine.
The SOMAS blow-off dampers are operated by pneumatic actuators, with switching times of two seconds to the open position and five seconds to the closed position. Control is automatic depending on the operating conditions. During commissioning, all blow-off dampers are open and are then closed one after the other once the critical pump speed range has been exited in order to keep temperature and performance jumps as small as possible.
At the same time, the turbine blade rows must be cooled with air so that the permissible material temperatures in the turbine are not exceeded. This requires cooling air control to ensure optimum cooling with low cooling air consumption.
The cooling air is extracted at various stages of the compressor. Some of it is routed via external extraction lines with SOMAS cooling air control dampers to the corresponding connection points on the turbine housing. These dampers are controlled by electric actuators and also have mechanical protection against complete closure to ensure minimum cooling of the blades at all times.
Successfully in operation
Blow-off valves and cooling air valves for gas turbines have been part of the SOMAS range for a long time. The valves installed in Leipheim are triple-eccentric control dampers whose technical details have been specially optimized. The dampers have now been in use on the Siemens Energy gas turbine SGT5-4000F for a year and fulfill their purpose with little maintenance.
