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Control valve of the electric power industry how to choose to choose

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 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 control valve, and then to briefly go over the portion of the power plant in different.

Simple power process is actually the cycle of water, steam flow, in this process to choose control valve is both 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 safety and reliability of the control valve.

We according to the system process to control valve selection.

Deputy boiler feed water valve, water valve, compound feed water regulator

Control requirements: control boiler into the water, to maintain the economic level and steam flow.

General condition requirements: boiler startup valve pressure of 100-300 kg, flow is small, when normal operation of the pressure difference is small, large flow, flow adjustable ratio of 75:1-100:1.

Valve: the valve body is made of WCB/wc9, for double valve cavitation resistance starting valve in the system requirements, to v closed ranks, the complex characteristics of the utilization of feed valve need to trim at the same time meet the needs of the boiler startup and normal operation. General valve selection for the fault clearance, (it"s important to note that the general to the water to remove dissolved oxygen will join diammonium for processing, it will be to # satellite6 alloy or other similar alloy adverse reaction, so it"s best not to use 316 + stellite trims the method of surfacing welding processing, can be directly choose 416 stainless steel material).

Boiler feed pump minimum flow circulation 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 power plants using the minimum flow control valve switch type, as well as the use of mechanical pump automatically circulating valve).

Condition: the pressure drop of 160-350 kg, is the largest power station in the system under differential pressure valve, flow generally 30% of the normal flow.

Valve requirements: resistance to cavitation, block structure, grade v seal level, the pump start and stop running when the valve work continuously, pump normal times since the start valve valve, valve is usually a failure.

High/low heater water heater drain trap 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: the medium is saturated water, heater control valve differential pressure is commonly between 6-30 kilograms, the last level of trap connected directly to the condenser or deaerator.

The valve

Valve requirements: resistance to flash scour, v or vi levels of seal, valve is usually a failure.

Deaerator water level control 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 differential is bigger, normal flow, small pressure difference, working condition of similar feed valve.

Valve requirements: effective during low flow resistance to cavitation,

Desuperheating valve (attemperator)

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

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

(high and low pressure bypass valve) the temperature and pressure-releasing valve

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

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

Valve requirements: thermal shock, noise reduction, response quickly.

Deaerator water level control 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 differential is bigger, normal flow, small pressure difference, working condition of similar feed valve.

Valve requirements: effective during low flow resistance to cavitation,

Desuperheating valve (attemperator)

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

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

(high and low pressure bypass valve) the temperature and pressure-releasing valve

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

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

Valve requirements: thermal shock, noise reduction, response quickly.


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