What is the power plant control valves? What is its working principle and application? How should we sized it? Jingyi valves, however, tells us that selection of the control valve in this process both simple and complex. Simple process medium is simple, only two kinds of water and steam, the complexity of the water and steam temperature and pressure fluctuation range, bringing a series of questions such as: flash, cavitation, erosion, noise and corrosion. But the first thing to consider is the safety and reliability of the control valve.
The water supply valve (main, boiler feed water valve, composite water valve) control requirements: control the boiler into the water to ensure steam evaporation, maintain boiler water level (primary, with a boiler to the valve system includes two control valves, one with at the start of the boiler, a water supply for normal use). Condition: The pressure valves in the boiler starts up to 100-300 kg, flow smaller, less pressure during normal operation, the flow rate, the flow adjustable ratio 75/1-100/1. Valve requirements: WCB/WC9 start valve dual valve system requires anti-cavitation Close Level V class pieces at the same time meet the needs of the boiler startup and normal operation, required for the compound to the water valve characterization valve. The general valve selected as the fault shut.
Boiler feed pump minimum flow valve cycle
Control requirements: the boiler feed pump safety start and stop the run, to eliminate the flow is too small, temperature increase, the strong cavitation pump water damage. (Old-fashioned power station to switch minimum flow control valves, as well as use of mechanical pumps automatically cycle valve). Condition: The pressure drop of 160-350 kg, which is 30% of the power plant systems to withstand pressure valves, flow of normal flow. Valve requirements: anti-cavitation, attempts to prevent the structure, V-class seal level, the pump start and stop running when the valve work continuously pump normally starts after the valve is closed, and the valve is usually opened for the failure.
Level of heater, heater drain condensate trap (Water Heater)
Control requirements: control heater condensate, condensate drain timely, high water discharge, hydrophobic normal water level. Condition: The saturated water heater control valve between the pressure is generally 6-30 kg, and finally a trap directly connected to the condenser or deaerator. Valve requirements: flash erosion resistance, V or VI seal level, the valve is usually opened for the failure. Deaerator water level control the valve (DALC) control requirements: provide flow to maintain the normal water level of the deaerator eliminated by adding steam to raise the water temperature of the gas dissolved in the water. Condition: The start-up phase flow of small and large temperature differential, the normal flow rate, pressure difference, the condition is similar to the valve. Valve requirements: low flow cavitation effect.
Desuperheater valve (desuperheater)
Control requirements: high-pressure water jet steam into the steam temperature to achieve the control requirements and conditions: water, differential pressure valve Requirements: the diverse type: nozzle type, assisted atomization type, self-contained type and on the clip.
Reduction Valve (high and low pressure bypass valve)
Control: adjust the high-temperature high-pressure steam to a certain temperature and pressure steam to the turbine to provide a bypass channel, boiler turbine capable of independent and work. Condition: The high temperature and high pressure steam. Valve requirements: thermal shock, noise reduction, quick response. Therefore, the people in the choice of power plant control valves can be candidates according to these requirements
|
