The rotor of a steam turbine is subjected to bending while they are operating. However, the supports of the turbine, as well as the bending, are designed in such a way that they separate the static forces from the dynamic forces and always keep them harnessed in an effective way. But, it is very common that due to the bending, there is an impact between the rotating parts of the turbine and the stationary elements. This is the cause of cascading impacts inside the turbines. Therefore, these cascading impacts are what we observe as vibrations in the Steam Turbines. In this article, we are going to learn about the cause of vibrations in a steam turbine.
Working of a Steam Turbine
As the name suggests, steam turbines are turbines that work by converting the heat energy of the steam into a rotating motion. A steam reservoir is placed along with the turbine for the whole mechanism to work properly. The first step that is required is the conversion of water into steam.
Therefore, water is subjected to extremely hot temperatures, and gradually the water turns into steam. This heating of water is done either by burning fossil fuels or with the use of solar energy. The water that is being heated in the boiler is connected to a chamber through which steam is transferred.
The steam is then transferred from the boiler to pump the steam turbine. The steam coming through the boiler rapidly rotates the blades of the turbine, and a mechanical rotation is achieved. These turbines are further connected with several other power generating sources such as generators, or pumps. Converting the rotational energy into other forms of storable energy.
The root cause of vibration in a steam turbine
One of the problems that power generation plants often face is rotor bending which causes failure in the power plant. This stops the proper rotation of the rotor blades and is the major reason for the reduced efficiency and productivity of power plants.
This reduces the generation of power in the power plant and additionally increases the maintenance cost. However, this rotor bending is due to the interaction between the rotating parts of the turbine with the stationary parts. This can cause vibration in the steam engine and is the reason for several problems.
Effects of rotor bending
Inadequate tolerances inside a system’s chamber or diaphragm frequently result in stroking, which could have a variety of detrimental impacts on the rotor, causing vibration. Furthermore, along with vibration, friction can cause rotor end sealing to fail. Interaction in between a high-speed rotor as well as a stationary material not only causes damage but also causes localized temperature rises, elevating the heating of the components due to friction.
Furthermore, this rubbing can cause elasticity deflection on the blades, resulting in an upsurge in noise and vibration. This bending can also result in permanent damage to the rotors and the components it comes in contact with. A steam turbine service will help you effectively to maintain the efficient working of your turbine.
Several causes of vibration in a steam turbine
There are several causes that can start a vibration in the steam turbine. Here are some of the reasons which can cause vibration in steam turbines:
· Uneven warming of a Turbine rotor
There are several conditions in steam turbines when their automatic rolling function is halted. Therefore, this causes the improper heating of the internal parts of the turbine. Consequently, the chances of uneven heating of the shaft increase due to which a rubbing is observed between the stationary and the rotatory parts. This further results in the bending of the shaft.
· Misalignment of Coupling
One of the factors that cause the turbines to vibrate is the misalignment of the coupling. Misalignment may be a cause of bending of the shafts and the bearing of the entire turbine system. This might cause an eccentricity altering the centre of mass of the rotor. A centrifugal force is developed along the rotating direction of the rotor. This increases the speed of rotation and may result in bending. This bending of the rotor blades causes vibration in the steam turbine.
· Rubbing of blades
Sometimes the blades of the turbine touch the other internal parts of the turbine. This may be due to several reasons which can be improper oiling of the blades or thermal expansion. Due to this, the tip of the blades rubs the internal parts of the turbine, while the blades are rotating. This impact causes vibrations in the entire turbine and can be a cause for the breakdown of the entire steam turbine.
Conclusion
Steam engines are an effective method of generation of power using renewable sources of energy. However, its operation is not as simple as it looks, thus there are several ways in which a turbine can fall apart. One of the causes of failures of these turbines is the vibration that is the result of a collision between rotating parts and the stationary part of the turbine. There are several ways in
which vibration can be fixed, early identification through professional consultations is critical to preserving optimal performance and minimizing machine damage.
