Turbine Bypass Valve | Image Resource : Chemtrols.com
The turbine bypass systems are very useful components in steam pressure and temperature control processes. They increase the flexibility of the steam power plants. The main advantage of bypass valves is that they assist in faster shutdowns and start –ups hence saving critical and expensive components from suffering significant damage owing to thermal transients. Apart from power plants these equipment are also useful in some of the boiler designs to ensure safe operations. Here is all the information you might need regarding the purpose, design and applications of turbine bypass systems.
Design and Components of Turbine Bypass Systems
These bypass systems comprise of various components including hardware such as steam – pressure reducing valve, desuperheater, spray water control valve, dump tube or sprayer and actuator. The performance of the turbine bypass valve has a strong effect on the heating rate of the plant and its capacity. The EFOR i.e. theEffective Forced Outage Rate is also controlled by bypass systems. Hence it is an important component which is crucial for the long term health and performance of the expensive and vital components of power plants such as steam turbines, boiler tubes and headers.
To ensure full efficiency all the components used in a turbine bypass system must be selected correctly keeping in mind the size and the capacity of the plant. The steam pressure reducing valve is a primary component which is essential to control the upstream pressure. It is available in various configurations. The final decision regarding the selection of the appropriate configuration of the pressure reducing valve can be made as per the plant layout and the user’s preference. The most simple and compact configuration is the angle – body design with flow – to – open configuration. It is a compact and lower weight package which is characterised by less demanding supporting requirements, simpler pre – warming requirements and special treatment that reduces noise at the outlet pipe.
Actuators are also a crucial component that ensures high performing turbine bypass systems.Modern day bypass systems use pneumatic actuators which are sized to offer fine control and to meet the high thrust requirement that is necessary for tight shutoff. Special electrohydraulic actuators are also available by various companies. The type of actuator plays a key role in describing the turbine bypass system. The selection of actuator type depends on the expertise of the end user and the plant design. The double acting pneumatic actuators are more reliable and simpler in construction.