Steam Turbines are one of the most widely utilized sources of power generation in the global market. Statistically, the market size of this industry is expected to expand at a CAGR of 2.8% by 2027. Created by Charles Parsons in 1884, the mechanism of these turbines runs on natural heat sources like coal, natural gas, or solar energy. This combines with water to produce heated steam which transports and adapts via the various steam turbine components.
During this transfer, the machine parts contribute to the overall energy production. For example, the spinning blades rotate the thermal energy output from the water-heat mixture and ultimately produce electric energy. Overall, all of the components of the steam turbines play an important role in the overall power creation. One of the notable mentions is the component of the governor.
In this article, you would learn more details on the functionality of the governor component of steam turbines specifically.
What is a steam turbine?
Governors are one of the crucial Steam Turbine Parts. Before focusing on the role of a governor, it is important to understand the basic mechanism of a steam turbine. Typically, a steam turbine is a device that extracts thermal energy from pressurized steam and uses it to do mechanical work on a rotating output shaft.
What is the function of a Governor
Related to the principal functionality of a steam turbine, its governor component bears a lot of responsibility. In general, A turbine moves at a rotational speed. While a certain amount of load generates a specific boost of energy, the load can keep adjusting in particular situations. That is when the Governor comes into action. Its output signal manipulates the position of the steam inlet valve or nozzle to regulate the rotational motion.
For example, should the load increase, the governor would ease the nozzle to release some of the pressure and vice-versa.
Modes of a Governor.
The governor generally is required to have two basic control modes.
- The Start-up Speed Controller- During the startup sequence, the Speed Controller overrides the control to orderly ramp up the steam turbine. That means, for the steam turbine governing to ramp up to adjust to each state, the startup controller would ignore the load value and read the maximum setpoint.
- Speed/Load Controller – This is the main function and purpose of a governor. The speed/load controller balances between the amount of pressure added to the load and the opening of the inlet nozzle that is controlled by the governor. For example, If the load is more than a given ramp, then the speed/load controller would find the balance by maintaining the inlet pressure.
Types of Governor Systems
While mainly the function of a governor stays remains the same, there are four major types of governor systems.
- By-Pass Governing: An additional amount of steam can release through the by-pass valve incorporated in the turbine in the later stages of the turbine. Here, the load is typically manageable to bear.
- Nozzle Governing: Consider that there are four openings to a nozzle. According to the pressure required, the nozzle valve will either open or close to regulate the load. For example, if the load is reduced, then one of the four nozzles will shut down.
- Throttle Governing: When the requirement of steam is less due to decreased load, the stop valve partially closes and the shaft speed increases. This occurs to ensure less steam admits into the turbine. This yields less power to meet the demanded power supply. There are two types of throttle governing, one for small turbines and for big turbines. While the mechanism for small turbines is fairly simple, for big turbines, an oil-operated servo mechanism is used that enhances the lever sensitivity.
- Combination Governing: It is the usage of any two types of governing to produce the best results. The general norm is to use bypass governing and Nozzle governing.
- Emergency Governing: As the name suggests, emergency governing is used in the worst-case scenarios. It is inhibited when:
- The mechanical shaft speed becomes more than 110% of its rated value
- The lubrication system perishes
- The condenser becomes too hot. This happens when there is a lack of cooling water or the vacuum in the condenser is scarce.
- There is an imbalance of the turbine
Types of Governors
Besides the various governing systems, there are different types of governors available as well:
- Centrifugal Governor
- Pendulum type
- Gravity Loaded
- Spring Loaded
- Inertia Governor
Steam turbines fall under the necessary category of different machine types. These systems are crucial parts of power plants and contribute highly to the overall energy output on a global scale. In this context, the governor is one of the most important components in the turbine body that influence its overall functionality and output rate. For accurate management and operation of steam turbines, understanding governor-oriented functions is important first.