Product - DAM-D Steam Desuperheater

​​​​​​​​​DAM-D: Steam Desuperheater

​The desuperheater DAM-D is typically used in combination with a steam pressure reducing valve to create a steam conditioning valve. The VLR steam conditioning valve uses the DAM-D as its desuperheating component. The DAM-D can be welded to the outlet or installed close downstream from the steam pressure reducing valve. Apart from providing desuperheating functionality to the upstream pressure reducing valve, the DAM-D also straightens the often very non-uniform flow patterns that are created by the pressure reducing valve. The DAM-D also reduces noise and creates a backpressure that reduces or eliminates high velocity in the valve’s outlet.

The DAM-D steam desuperheater is used in desuperheater applications where large spray water flows are required.
​​​

Key features


The DAM-D desuperheater consists of two stages. The first stage, the pressure reducing stage, consists of one or several perforated cylinders installed directly after the desuperheater inlet. The second stage consists of a series of mechanically opening spray nozzles inserted in to the desuperheater outlet. The size of nozzles, their number and insertion length may vary depending on steam desuperheating needs. In case of large pipes, they may use multiple insertion lengths in order to improve coverage. The spray nozzles receive water from a common water pipe encircling the desuperheater. The spray water flow must be controlled externally through a water control valve.

Pressure reduction
Pressure reduction in the desuperheater depends on the number of pipes installed after the inlet, as well as their drill patterns. Placing the pipes in the DAM-D reduces the necessary outlet size of the upstream pressure control valve when installed separately. It can also provide this feature to an existing pressure control valve when a secondary pressure reducing stage is desired.

Flow pattern
The pressure reducing pipes straighten the often non-uniform flow patterns created by the upstream pressure control valve, and create a backpressure that reduces and/or eliminates high velocitiesin its outlet. They also redirect the flow towards the center of the pipe and water away from the pipe wall, removing the need for a thermal liner. The increased steam flow speed caused by the pipes creates higher dynamic forces acting on the water droplets injected by the spray nozzles, improving their evaporation.

Noise abatement
The multiple pressure-reducing pipes serve as a diffuser, where the steam flow is broken up into a great number of partial fluid jets. This improves the rapid dissipation of kinetic energy in the steam, resulting in a substantially reduced emission of noise and vibration.

​Benefits

  • Flow pattern eliminating the need for thermal liner
  • Nozzle prevents flashing
  • Each nozzle maintains a differential pressure for water atomisation regardless of flow rate
  • Designed to handle large spray water flow quantities
  • Distributes water evenly over the cross section of the steam
  • Prevents water impingement on downstream piping (candy striping)
  • Nozzle assembly includes a thermal barrier preventing thermal shock between the water and the hot outlet
  • Connections customised for the application
  • Provides up to three pressure reducing stages as standard
  • Reduces upstream valve outlet size

Spray nozzles


The atomising spray nozzle is housed inside a nozzle holder inserted into the pipe outlet. Water is routed through the pipe leg and the nozzle chamber before being supplied to the spray nozzle.
  • The nozzle itself has a spring loaded plug which extends as the pressure in nozzle holder increases. The amount of water being injected by each nozzle is determined by a number of factors, including the diameter of the nozzle body opening, adjustment of the spring, and the pressure differential between the steam pipeline and the water pipeline.
  • The cooling water enters the inner nozzle chamber through a number of water channels. Water is rotated around the nozzle plug thanks to the special arrangement of the water channels. The plug and the seat are designed to create maximum water velocity at the nozzle edge point. The high velocity of the water
  • when it leaves the nozzle guarantees fine atomisation, quickly evaporating the spray water.
  • In order to maintain a specific opening water pressure inside the inner nozzle chamber, the nozzle plug is preloaded by a spring. The force required to open the nozzle is set by the adjustment nut.
  • As the nozzles spray perpendicular to the steam flow, the high relative velocity of water to steam creates an efficient secondary level of atomisation.

Configurations

Welded to a pressure control valve
The DAM-D is often used in combination with a pressure reducing control valve as a desuperheating component. It can be welded directly to the outlet of the valve, creating a complete steam conditioning valve. Common examples can be seen in the examples below.

Alternative set-up
An alternative to using DAM-D is using a VLB.
  • DRAG® + DAM-D
    • A desuperheater welded to the outlet of a DRAGR pressure control valve.
  • VSG-C + DAM-D
    • A desuperheater welded to the outlet of a VSG pressure control valve.

DAM-D with separate pressure control valve
This is an example where a bent pipe separates the VLR pressure control valve and the desuperheater. The DAM-D requires a minimum distance of straight pipe for the injected water droplets to completely evaporate, and for the temperature control system to function reliably. More information on desuperheater/valve installations can be found in II500.00 - Installation Guidelines. In this case the pressure control valve had to be placed just before a bend, but the desuperheater still has a recommended length of downstream straight pipe.

General product specification​​

Capacity
Unlimited (Depends on size and number of orifices)

Materials
Steam pipe material is adapted to connecting pipe material.
Nozzles and springs are made from X19CrMoVNb11.1* as standard

Rangeability
Nozzle turndown:
Limited only by turndown of selected water control valve.
System turndown:
Minimum steam velocity or temperature control is typically 4-6 m/s (13-20 ft/s) downstream depending on steam pressure

Pressure class
DIN PN 16-320
ANSI 150-2500
*Alternative nozzle and spring material in Inconel is available for high temperature applications and conditions without water injection.

Opening Pressure (OP) nozzle specification

​Spring-loaded OP nozzles come in a number of sizes with different capacities and opening pressures.
Opening pressure (Δp) is defined as the pressure differential between the water inlet and the DAM outlet.
Q0 = Required cooling water flow (l/m)

Example​

In applications where the steam pipe configuration makes it impossible to use a complete steam conditioning valve such as the VLB, it is possible to use a VLR steam pressure reducing valve and a DAM-D desuperheater welded to the pipe and achieve the same function. In this case the pressure reducing valve is installed perpendicular to the desuperheater, with a 90° bended steam pipe connecting the two.
 
Spray water is injected into the steam using a series of mechanically atomising spray nozzles encircling the desuperheater outlet. The spray water flow is controlled by a water control valve connected to the DAM-D water inlet pipe.



Latest News

Valve Doctor programme celebrates 20th anniversary
16 September 2019
Unconventional support for the unconventional oil and gas industry
01 July 2019
INWED19
17 June 2019
IMI CCI showcases choke valve at DUG Rockies conference
04 June 2019
Jackie Hu appointed Divisional Managing Director of IMI Critical Engineering
07 March 2019
Roy Twite to succeed Mark Selway as Chief Executive of IMI plc
05 March 2019
IMI Critical holds Safety Summit
21 September 2018
New HSE handbook to help keep field service engineers safe
10 August 2018
Safety first at IMI Critical
31 July 2018
IMI InterAtiva’s Series RK Valves certified ‘fire-safe’
24 July 2018
IMI CCI participates at regional VPP Safety Summit
08 June 2018
Largest Romanian customer recommends IMI Remosa
10 May 2018
Lean success in IMI Critical back office functions
04 May 2018
Isolation valves adapted for Fluidised Catalytic Cracking applications
30 April 2018
IMI Critical Korea closes in on world-class LEAN performance
27 April 2018
IMI board tours IMI Critical businesses
25 April 2018
New positioner software tools from IMI STI
08 February 2018
Launch of Zero Backlash Scotch Yoke Mechanism
16 January 2018
IMI Critical Korea certified to sell actuators in Europe
20 September 2017
IMI Critical named ‘supplier of the year’ by Korea’s Doosan
19 September 2017
100th Valve Doctor graduates from IMI Critical
13 September 2017
Top HSE certification for IMI Critical’s California site
12 September 2017
Launch of High Endurance Actuator
21 April 2017
Launch of AB6350 valve
06 April 2017
Launch of 100DPC Multi-trim
17 March 2017
Launch of 840GS control valve
22 December 2016
IMI Critical to exhibit new technology at ADIPEC 2016
25 October 2016
New graduates join IMI Critical in four countries
22 September 2016
IMI Critical to take stand at ONS 2016 in Norway
16 August 2016
IMI Critical opens new China plant in Qingpu
27 July 2016
IMI CCI Korea celebrates 2,000 days of no “Lost Time Accident”
25 July 2016
Visit to IMI Z&J Germany by the Russian Economic Bureau from Bonn
11 July 2016
IMI Z&J Düren moves into modern offices
08 July 2016
IMI Critical Engineering forms strategic partnership with MRC Solberg & Andersen
05 April 2016
IMI Way Day 2016 date announced
01 March 2016
NEW IMI Eye – fourth edition
26 February 2016
IMI Critical co-locates China businesses
20 January 2016
IMI CCI Switzerland gains certification for new generation safety valves
18 December 2015
IMI Critical rise to Dragon challenge
30 November 2015
IMI STI achieves CRCC approval for new products
24 November 2015
IMI Truflo Marine Attend the Engineering Technology and Innovation Exhibition 2015
23 November 2015
IMI CCI Sweden secures new contracts on three continents
23 November 2015
IMI Critical Engineering appoints new petrochemicals head
05 November 2015
IMI CCI Czech Republic gains ‘Safe Enterprise’ certification
03 November 2015
IMI Critical announces 90mRMB investment in China
29 October 2015
IMI CCI SriCity wins regional safety award
27 October 2015
Key clients attend grand opening of new Aberdeen facility
23 October 2015
IMI companies ‘act as one’ to deliver for customer
02 October 2015
IMI CCI Sri City approved by NTPC
01 October 2015
IMI Critical Engineering showcases innovation at Valve World Expo Asia
28 September 2015
Nexen awards IMI Orton
25 September 2015
IMI Critical Engineering celebrates opening of new Jubail repair centre
23 September 2015
IMI Critical and IMI Precision join forces at Valve World Expo + Conference Asia 2015
21 September 2015
IMI Critical Engineering opening of new Jubail Repair Centre
18 September 2015
IMI CCI India manufactures first 1050MW turbine bypass valve
20 May 2015
Largest ever contract for IMI Critical Engineering
18 February 2015
New Houston facility opens
12 February 2015
IMI Critical completes acquisition of Bopp + Reuther
02 January 2015
IMI Critical takes family of brands to Valve World 2014
11 December 2014
IMI STI doubles size of Italian plant
20 October 2014

Downloads

Contacts

​Global sales:
imicci.sales@imi-critical.com​​​
Product - DAM-D Steam Desuperheater