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Desuperheaters
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Desuperheaters

Desuperheaters

Transvac direct contact steam Desuperheaters (also known as attemperators) are used as a method of steam temperature control, reducing the temperature of superheated steam. A desuperheater’s function is to produce steam temperatures approaching saturation temperature (typically to within 3°C). To cool the superheated steam, a medium, usually water, is entrained and flashed into vapour by absorbing heat from the steam.

 

For steam recovery solutions, please visit our Thermocompressors page.

 

Applications

  • To reduce the temperature of steam discharged from turbine by-pass systems on power plants for heat exchangers, dump stations etc.
  • To improve heat transfer efficiency of indirect contact heat exchangers – shell & tube, plate-type, reactor heating jackets
  • To reduce the temperature of steam on direct contact applications such as food cooking kettles, in-line steam heaters, tobacco drying plant and paper mills

 

Advantages

  • Low cost, simple, robust design
  • No moving parts to wear
  • Minimal steam pressure drops
  • Flexible design options

 

Construction

Our units are available built to our own proprietary codes of practice (typically ASME B31.3) or to ASME VIII Div 1, PD5500, Stoomwezen and other recognised design codes. Units can be CE marked on request. Connections are sized to suit the process conditions. Standard materials of construction include carbon steel or stainless steel. For high temperature applications we offer chrome molybdenum steel (F11, P11, F22, P22 etc), however we can also manufacture in other metals or alloys requested.

 

Which model is right for my application?

 

Please note this is a general guide and does not represent every option available. Please contact us if you have any queries.

 

Spray Type Desuperheaters

A simple in-line model where cooling water injected into the centre of the unit via an atomizing nozzle sprayed in the direction of the steam flow.

 

1. Simple Spray Type Nozzle (SND)

The assembly is designed for mounting on a suitable flanged branch on the steam pipework. A thermal sleeve installed downstream of the unit is recommended.

 

2. Complete Spray Type (STD)

A complete unit ready for installation including spray nozzle, nozzle housing, thermal sleeve within a flanged shell.

 

Applications

  • Relatively constant load handling duties
  • Turndowns up to 3:1 depending upon conditions
  • Turndowns 5:1 for some applications

 

Venturi Type Desuperheaters (VTD)

The venturi principle is used to create regions of high velocity and turbulence which produces intimate contact between the steam and cooling water.

 

Applications

Suitable for most general plant applications, except where high turndowns on cooling water are required.

  • Turndown 10:1

 

Steam Atomizing Type Desuperheaters (SAD)

A high-pressure auxiliary steam supply is used to atomize the incoming water within the diffuser of the unit.

The auxiliary steam pressure needs to be at least 1.5 times the inlet pressure with a minimum pressure of 3 barg.

 

Applications

Turndown to 20:1 or 50:1 with water recycle

 

Desuperheating & Pressure Reducing Stations

Transvac can provide complete Desuperheating & pressure reducing stations, including control valves, temperature sensors, pressure transmitters, instrumentation and pipework, all mounted on a support skid.