Control of the electric power industry for pneumatic valve selection

abstract: the control in the electric power is one of the most important energy industry, there are steam, wind, hydro, geothermal, tidal power, solar power, this article focuses on fuel, kerosene, gas and nuclear power plants in the selection of some typical control pneumatic valve. Such power stations have in common is that the water into steam, use steam to drive a steam turbine turns a generator to produce electricity, the difference is the energy of turning water into steam, respectively, are: natural gas, fuel oil, coal, atomic pile. All kinds of plant structure is roughly same, we first combined cycle power plant as an example to briefly describes the selection of pneumatic control valve, and then to briefly go over the portion of the power plant in different.

simple view of power flow diagram is, in fact, water, steam cycle process, pneumatic control valve is used in the in this process is simple and complex. Simple is simple process medium, only two kinds of water and steam, water is complex and steam temperature and pressure range is big, bring a series of problems such as: flashing, cavitation, erosion, corrosion, noise. But the first thing to consider is to control the safety and reliability of pneumatic valve.

we according to the system to control the process of pneumatic valve selection.

vice boiler feed water supply pneumatic valve main, pneumatic valve, compound feed water regulating pneumatic valve

control requirements: control boiler feed water, maintain the economic level and steam flow.

working condition requirements: boiler startup pressure pneumatic valve - general Kg, flow is small, when normal operation of the pressure difference is small, large flow, flow adjustable ratio for: - :。 Pneumatic valve requirements:

pneumatic valve body material for WCB/WC, for double pneumatic valve in the system to start the pneumatic valve requires the cavitation resistance, V level off, the compound feed pneumatic valve need to use characterization of pneumatic trims at the same time meet the needs of the boiler startup and normal operation. General pneumatic valve selection for the failure, ( Need to be aware of is generally for the water to remove dissolved oxygen will join diammonium for processing, it will be on the SATELLITE, alloy or other similar alloys adverse reaction, so it's best not to use the method of surfacing STELLITE processing pneumatic trims, can be directly choose stainless steel material.

the boiler feed water pump minimum flow loop pneumatic valve

control requirements: the boiler feed water pump start-up and safe operation and eliminating because flow is too small, temperature increase, water pump cavitation damage. ( Old plant is using the minimum flow control mode of pneumatic valves, as well as the use of mechanical pump automatic cycle of pneumatic valve.

condition: da pressure drop Kg, is the largest power station in the system under differential pressure pneumatic valve, flow is generally normal flow %.

pneumatic valve requirements: resistance to cavitation, block structure, grade V seal level, the pump start and stop the runtime continuous working pneumatic valve, pump to normal after the start time of pneumatic valve pneumatic valve, pneumatic valve is usually a failure.

high/low heater drain pneumatic valve feed water heater hydrophobic, condensed water heater hydrophobic

control requirements: control the location of condensed water heater, timely will be condensed water discharge, high water discharge, namely hydrophobic normal water level.

condition: medium for saturated water, heater control pneumatic valve differential pressure is commonly - between Kg, the final level of hydrophobic pneumatic valve connected directly to the condenser or deaerator.

pneumatic valve requirements: resistance to flash scour, V or VI seal level, pneumatic valve is usually a failure.

the deaerator water level control pneumatic valve ( DALC

control requirements: provide traffic maintain the normal water level, deaerator eliminated by adding steam temperature gas dissolved in the water.

condition: startup phase flow is small, the pressure difference is bigger, normal flow, small pressure difference, working condition of similar water supply pneumatic valve. Pneumatic valve requirements:

effective during low flow resistance to cavitation,

desuperheating pneumatic valve ( Attemperator

control requirements: the high pressure water injection into the steam to steam temperature control requirements.

condition: medium is water, the pressure difference is bigger, pneumatic valve requirements: a variety of types: type nozzle, auxiliary atomization type, self-contained type and type to the clamp.

desuperheating decompression pneumatic valve ( High and low pressure pneumatic valve circuit

control requirements: the high temperature and high pressure steam to adjust to a certain temperature and pressure of steam; To the turbine to provide a bypass channel, boiler turbine and work independently.

conditions: high temperature and high pressure steam to reduce temperature and pressure relief.

pneumatic valve requirements: thermal shock, noise reduction, response quickly.