DESUPER HEATER

DESUPER HEATER

Flow-Tek Desuperheater leading suppliers of Steam Desuperheaters. We specialize in designing and manufacturing such equipment for power, process and co-generation plants.
STEAM DESUPERHEATERING The most practical way of reducing the superheat value of steam is by the direct addition of water. To achieve temperature stability of the conditioned steam and prevent thermal shock in downstream pipes, cooling water must be atomized. It is also necessary to have a correct mix of superheated steam and cooling water.

  • Modular and compact design
  • No cooling water control valve required
  • Ultra-fine atomization
  • Patented nozzle design
  • Simple installation
  • High differential pressures possible

Effective Desuperheating
The potential to reduce the degree of outlet superheat is limited by the capability of control system. Almost all desuperheaters are used to reduce the steam (or gas) temperature as close to saturation as possible.
Most desuperheater models (types) are actually capable of achieving saturation or close to the saturation. The caveatis that these units must be controlled precisely to prevent flooding of the whole system. The limitation of the control system is its sensitivity range. Consider a system with a controlled outlet temperature set at 1 °C above the saturation, where the controls are designed to maintain +/- 1 Deg.C.
The cooling water injection into the steam will continue till the temperature falls to saturation.. Then only the controls will reduce the cooling water injection. Due to the delays inherent in the control system (specifically introduction of derivative band) which is not in scope of desuperheater manufacturer, cooling water will continue to flow at the design rate for a short time. In that small amount of time, the saturated steam will be allowed to condense. Condensing vapor creates a vacuum, which sucks in more vapor, which too continues to condense. This results in loss of control, downstream equipment may be damaged & the downstream processes may be severely affected. Due to these reasons, we have opted to not guarantee desuperheating lower than 4 - 5 °C above the saturation. The downstream processes do not suffer much from such small amount of superheat.

Recommendations for efficient working of DSH

  • Minimum straight length at outlet should be 4 mtrs.
  • Minimum distance of Temperature Sensor from the point of water injection should be 10 to 12 mtrs.
  • Water pressure should be minimum 7 bar more than the steam pressure.
  • Maximum recommended pressure difference between steam and water is 45 bar. If it exceeds 45 bar then install pressure control valve in waterline to reduce water pressure within limits.
  • Spray water should be very clean (equivalent to boiler feedwater).
  • It is recommended to install a strainer of 0.8 mm mesh before water control valve.
  • Spray water should be very clean (equivalent to boiler feedwater).
  • Instrument quality air is required.
  • Minimum controllable temperature is Saturation temperature + 7°C
  • Minimum inlet velocity should be 15mts/sec for FND and 7mts/sec for VND.
  • It is necessary to keep the steam flow rates (for max. and min conditions) as practical as possible. Else the turndown ratio increases unnecessarily which necessitates the selection and use of a combination of nozzles in the same spray cylinder
  • STEAM

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