Reduce pressure and Desuperheaters system

feedwater control valve(control feed water flow rate to desuperheater)

according to process conditions selection feed water control valves.

Desuperheaters:

sizes:2″~16″
ANSI Class 150 to 2500
fabricated and forged constructions
High quality stuffing box
Variable nozzle type
Wide range of Cv(Kv) capacities available
Special nozzle combinations available

Application data

  • Boiler superheaters
  • Boiler reheaters
  • Turbine bleed steam
  • Pressure reducing valve outlet steam
  • Process steam
  • process gas

Every desuperheating station is a mixing point where there is a heat and mass balance. the universal formula is:

Gw=Gst(h1-h2)/(h2-hw)
where:
Gw—Injection water mass
Gst—Inlet steam mass
h1—Enthalpy of inlet steam
h2—Enthalpy of the outlet steam
hw—-Enthalpy of the injection water

This formula enables calculation of the quantity of water required to lower the inlet steam temperature to the the set-point temperature of the outlet steam.

Apart from the spray quality of the atomizer(primary atomization)there are other system parameters which influence the desuperhearter stations performance.These are:

Inlet steam velocity

At high steam velocities, water droplets are easily disintegrated.This factor contributes to the overall atomization quality(secondary atomization). The minimum acceptable steam velocity varies as a function of the nozzle size and pipe diameter.In case of doubt,  consult Proactive control valve team.

Water to steam ratio

This ratio is determined by dividing Gw by Gst. For system steam pressures below 15 bar,this ratio should nor exceed 10% for the normal operating conditions.system operating between 15 to 25 bar can have a ratio of up to 15%. For higher pressure duties , consult Proactive control valve team.

Distance to sensor

The distance from the injection point to the temperature sensor should be 12 to 15 meters. Systems operating at pressures above 25 bar can have significantly less run to the sensor.consult Proactive control valve team.

Required straight pipe run

The distance from injection point to the first pipe bend is also a function of steam pressure,temperature and nozzle size. Experience has shown that in systems up to 25 bar,4 to 6 meters is acceptable distance.

Spring back pressure nozzle

Desuperheater may be equipped with a variety of spray heads.The uniform body welding accepts spray cylinder heads with a wide range of Kv(Cv) values.Standard configurations are with either 3 or 6 equally sized spray nozzle but combinations are available.this feature enables Desuperheater to be customized to specific system requirements.

Feature

  • high Rangeability:200:1
  • pressure adjustment range:1.5-8 bar
  • no droplet form
  • Fan-shaped surface out
  • Misty,Average size of water droplet:60um
  • anti-cavitation
  • Anti-blocking, self cleaning
  • no need for check valve

Reduce pressure: