The employment of power station control valves is more unique in the thermal power industry. The power flow is merely water in a steam cycle process, yet the control valve casting is both simple and complicated.
Simple indicates that the process medium is simple, with just two types of water and steam; complicated means that the temperature and pressure fluctuation range of water and steam is broad, resulting in a slew of issues such as flash, cavitation, erosion, noise, corrosion, and so on. However, the first item to evaluate is the control valve’s safety and dependability.
Commonly Used Valves in Power Plants
1. Water Flow Valve
Control boiler water intake, assure steam evaporation and maintain boiler water level main and attached type boiler feed valve casting systems have two control valves, one for boiler start-up and one for routine feed water usage.
When the boiler first begins, the valve pressure difference can reach 100-300 kg, the flow rate is small, the typical operating pressure difference is modest, the flow rate is large, and the flow rate adjustable ratio is 75:1 100:1.
WCB / WC9, for a dual valve system to begin the valve requirements of cavitation, class V closed class, for the composite water valve to utilize the characteristics of valve internals, and to fulfill the demands of the boiler’s start-up and normal operation.
2. Minimum Flow Circulation Valve for the Boiler Feed Pump
Make the boiler feed water pump start and stop operation safely in order to minimize small flow, temperature rise, and water cavitation caused by pump damage. Older power plants used on-off type minimum flow control valves as well as mechanical pump automatic circulation valves.
Pressure drop of 160-350 kg, power station system to resist pressure differential of the biggest valve, flow for the normal flow of 30%.
Valve criteria include anti-cavitation, anti-blocking structure, v Seal class, pump start and stop operation of the valve continuous work, pump normal start after the valve closed, and the valve is typically open for failure.
3. Heater Traps for High and Low Temperatures
Control requirements include controlling the placement of condensate in the heater, timely discharge of condensate, discharge of high water levels, and drainage of normal water levels.
Saturated water, a pressure differential between the heaters of 6-30 kg, and the last level of steam trap immediately linked to the condenser or deaerator.
Valve casting criteria include flash resistance, a V or VI seal class, and a valve that is typically open for failure.
4. Control Valve for Deaerator Level
Supply flow to maintain normal water level deaerator by adding steam to raise water temperature to remove dissolved gases in water.
The start-up phase flow is modest, there is a big temperature pressure difference, the typical flow is considerable, there is a minor pressure difference, and the operating circumstances are comparable to those of a water valve.
Valve specifications include effective cavitation resistance at low flow rates.
5. Thermocouple Temperature Reducing Valve
High-pressure water injection into the steam to raise the temperature to control levels. Water with a large pressure differential.
Valve specifications include the following: nozzle type, auxiliary atomization type, self-contained type, and clamp type.
6. Valves for Reducing Temperature and Pressure
High-temperature and high-pressure steam is regulated to a certain temperature and pressure of the steam engine to create a bypass channel, allowing the boiler to operate independently of the turbine.
High temperature and high-pressure steam are the working conditions.
Thermal shock resistance, noise reduction, and fast response are all criteria for valves.
While basic valve design principles have not altered, valve casting materials and manufacturing processes have substantially improved. With this in mind, valves may now work more intelligently and efficiently. This page discusses valves used in power plants, their importance, and their classifications.