What are the protection devices of a steam generator?

What are the protection devices for steam generators?

The main protection devices for steam generators include safety valves, pressure gauges, and water level gauges.

Safety Valve

I. Types of Safety Valves

Common safety valves used in industrial boilers can be categorized into three types based on the method of applying pressure to the valve core: dead-weight type, spring type, and lever type. Based on the lift height of the valve core during opening, they can be classified as low-lift type and full-lift type.

If d is the throat diameter of the valve seat and h is the lift height of the valve core, when h ≥ (1/4)d, it is called a full-lift type; when h is between (1/40)d and (1/20)d, it is called a low-lift type.

The outer diameter of the low-lift safety valve's core is the same as or slightly larger than the outer diameter of the valve seat sealing surface. When steam flows out, the upward thrust on the valve core is relatively small, resulting in a relatively rapid opening and closing action. This type is generally suitable for pressure relief of liquid media.

Full-lift safety valves have a larger disc on the valve core. When steam flows out, it generates a greater upward thrust, allowing the valve core to lift significantly. This type of safety valve opens and closes more gently, has a large exhaust capacity, and good reseating performance, making it suitable for pressure relief of gas media.

II. Models of Safety Valves

The model, specifications, and parameters of safety valves mainly include the connection method, structural type, sealing material, valve body material, nominal pressure, and nominal diameter. For details, refer to the next section.

For spring-type safety valves, due to the characteristics of the spring itself, the pressure range of each spring is limited. Therefore, a spring-type safety valve with a specific nominal pressure is equipped with springs of different pressure levels. Within a certain pressure level range, the safety valve can ensure a certain level of sensitivity. When selecting, it is necessary to choose the safety valve based on the required opening pressure for the steam generator's operating pressure and specify the spring's pressure level. The sealing pressure levels of commonly used spring-type safety valves for steam generators are shown in the table below. If no specific requirements are provided during purchase, they are generally supplied according to the PⅤ level.