BULLETIN 1144 SEPTEMBER 2001

MNSD-VMULTIPLE NOZZLESPRAY DESUPERHEATER

MNSD V MULTIPLE NOZZLE SPRAYDESUPERHEATER

2 © DeZURIK/Copes-Vulcan, September 2001

Features• Temperature control to within 15°F (8°C) of saturation with the ability to hold set point within a tolerance of

10°F (6°C)

• Standard maximum available Cv of 10.5 (Kv of 8.9)

• Waterflow turndown of 150:1 or higher

• User friendly design — nozzles and trim assembly can be removed without disconnecting actuator

• No need for separate cooling water control valve

• Designed for applications with temperatures up to 1150°F (620°C)

• Available in standard classes 600, 900, 1500 and 2500 per ANSI B16.5

• Cooling water inlet pressures up to 3500 psig (24 MPag) allowable standard (higher pressures allowable per application)

• FCI 70-2/ANSI Class V tight shutoff capability

• Suitable for vertical or horizontal installation

• Standard ANSI connections:3" (80mm) raised face flange (steam)

1.5" (40mm) raised face flange (water)

• Designed for high thermalfatigue life

The Multiple Nozzle Spray Desuperheater offersoptimum performance and rangeability in avariable spray tube design. The Model MNSD-Vfills the performance gap between the limitedcapability of a simple mechanical spray typedesuperheater and the virtually unlimitedcapability of DeZURIK/Copes-Vulcan’s VariableOrifice Desuperheater (Model VO). And, the newMNSD-V offers high temperature capabilities andlow class V leakage rating.

Many applications require turndowns in excessof that offered by a simple mechanical spraydesuperheater but do not necessarily warrantthe expense or require the additional refinementsoffered by the Variable Orifice Desuperheater.Many of these intermediate duties can be metwith a steam atomizing type desuperheater (SA-35), but atomizing steam is often not available, orthe additional installation and operational expenseis not economically justified. The Multiple NozzleSpray Desuperheater has been designed forthese applications.

Multiple Nozzle Spray DesuperheaterOffers High Temperature Capabilities and Low Class V Leakage Rating

The MNSD-V Desuperheater automaticallycontrols the cooling water flow with the ability tomodulate and shutoff. A separate cooling watercontrol valve is not required as the unit itselfcontrols variations in required coolant flow. Unlikecompetitive models that can only operate withrelatively low water inlet pressures, the MNSD-Vcan be supplied to accept cooling water inletpressures to 3500 psig (24 MPag). This eliminatesthe need for a cooling water pressure reducingvalve often required by competitive models andalso allows for much higher flow rates for a givenCv/Kv rating.

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Design and Principle of OperationThe MNSD-V Multiple Nozzle SprayDesuperheater consists essentially of a cage-guided plug situated within the nozzle tubejust behind the discharge nozzles.

The nozzle tube assembly fits up into the bore ofthe mounting flange and is locked in place with athreaded ring. This junction enables the coolingwater inlet connection to orient in any directionrelative to the position of the discharge nozzlespray at time of assembly.* Field alteration ofthis orientation is also quite easy.

The MNSD-V Desuperheater head offers a meansof mounting the unit to a companion flange onthe main header. It also provides an inlet connec-tion for the cooling water, a gland assembly forstem sealing and a mounting arrangement for thedependable DeZURIK/Copes-Vulcan Model 700Diaphragm Actuator.

*Standard orientation is cooling water inlet directly opposite spray outlet.

Discharge NozzlesThe multiple nozzle arrangement located nearthe end of the nozzle tube is composed of up to22 uniquely designed discharge nozzles arrangedin an overlapping manner to offer an extremelysmooth flow characteristic. The quantity,individual sizes and placement of the dischargenozzles are selected for each application tooptimize capacity and maximize controllabilityand rangeability.

Closed Open

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Cooling Water

Vapor

Cooling Water

The cooling water is admitted to the nozzle tubeassembly through the branch in the mounting head.

It reaches the lower portion of the nozzle tubeassembly as the plug exposes the nozzles. With theplug seated, no cooling water can reach thedischarge nozzles.

As the plug is extended by the actuator under thedictates of the temperature control loop, coolingwater is throttled at each exposed nozzle throughflow charaterization slots located just prior to thedischarge needles.

Optimum Desuperheater Efficiency

The cooling water then passes through speciallydesigned swirl discharge nozzles. Most of theenergy available from the differential pressurebetween the cooling medium and the main headeris expended while expanded through the nozzleswhich intensifies mechanical atomization. Theresulting soft, misty spray has a very low exitvelocity. This promotes rapid absorption andoptimum desuperheater efficiency, even at verylow flow rates.

The spray from the first discharge nozzle, andtypically the smallest, is quickly dispersed withinan average of 3' (1m) from the point of discharge.As the plug continues to modulate open, a swirlinginteraction of the various discharge nozzle spraysmaintains a narrow cone shaped pattern. Thiskeeps the water particles in the center of theheader where the line turbulence is the greatestallowing for faster, more complete absorption ofthe cooling medium.

Typical Information Required to Size:• Process steam flow rates• Process steam pressure• Process steam temperature

(superheated) • Desired process steam temperature

(desuperheated) • Available cooling water pressure• Available cooling water temperature• Process steam line size and schedule

Sizing SelectionThe MNSD-V and all DeZURIK/Copes-Vulcan desuperheaters can be sizedby DeZURIK/Copes-Vulcan or anauthorized sales representative usingSmartSize computer sizing program to assure correct application.

Installation RecommendationsFor optimum control and performance, apply the following guidelines:

• If the difference between the cooling medium and the header vapor temperature is greater than 450˚F (250˚C), and if the main header wall thickness is greater than .5" (12mm),

a thermal liner is recommended.

• For applications where unfiltered cooling medium is used, a 30 mesh strainer isrecommended for installation upstream of the cooling medium inlet.

xx

xx

Positioner

MNSD VTemperatureController

TemperatureSensor

Cooling Water

16–40'(5–12m)

Depending on Nozzle Configuration and Velocity

Vapor

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Materials of Construction

Item MaterialASTM A217, Grade WC6

Body Casting ASTM A217, Grade WC9ASTM A217, Grade C12AASTM A351, Grade CF8M

Cage & Torque Ring ASTM A565, Grade 616, Type 422, Hardened

Extension Leg ASTM A182, Grade F22ASTM A565, Grade 616, Type 422, Hardened

Retaining Ring: ASTM A479, Type 410, Hardened(For SprayTube Assembly)

Plug and Guide ASTM A565, Grade 616, Type 422, HardenedBushing

Plug C-Seal Inconel X-750 with Silver Plating

Orifice Disc ASTM A276, Type 420, Hardened

Swirl Disc 300 Series Stainless Steel

Spacer ASTM A479, Type 304

Seal Rings Graphite Grade JP-1000

Roll Pin 300 Series Stainless Steel

Seal Graphite with 316 SS (Body/Extension Leg)(Cage/Extension Leg)

Seat UNS R3006 Stellite 6

Stem and Stem Nut ASTM A276, Type 316, Cond. B

‘J’-Flanged Endsper B16.5

Header

Bottom ofMountingFlange

Reverse Acting

(Spring-To-Open)

D

C

D

H G

A

E

Main Header Size A

3" (80mm) Model 700 Class 150 through 1500

ActuatorSize B C D E F G H J Flange

39.31998.5

40.371025.4

160

160L

31.31795

39.751010

18.00457

18.00457

6152

6152

9229

9229

39.31998

47.751213

32.38822

40.811037

1.540

1.540

Dimensions

3" (80mm) Model 700 Class 2500

ActuatorSize B C D E F G H J Flange

40.3110245

41.371051

160

160L

31.31795

39.751010

18.00457

18.00457

7178

7178

9.5241

9.5241

41.371051

49.811265

32.38822

40.811037

1.540

1.540

Dimensions

3" (80mm) Mounting Flange Size

6" 12.06150mm 306

8" 13.06200mm 332

10" 14.12250mm 358

12" 15.12300mm 384

14" 15.75350mm 400

16" 16.75400mm 425.4

18" 17.5450mm 451

20" 18.75500mm 477

22" 19.75550mm 502

24" 20.75600mm 527

30" 23.63750mm 600

DimensionsDirect Acting

(Spring-To-Close)

*Supplied by Customer

F

MountingFlangeper B16.5

15.19385.817.19

385.8

B

DeZURIK/Copes–Vulcan reserves the right to incorporate our latest design and material changes without notice or obligation.Design features, materials of construction and dimensional data, as described in this bulletin, are provided for your information onlyand should not be relied upon unless confirmed in writing by DeZURIK/Copes–Vulcan. Certified drawings are available upon request.

Printed in the U.S.A. 080101

250 Riverside Ave. N. • Sartell, MN 56377 • Telephone: 320-259-2000 • Fax: 320-259-2227E-Mail: info@dezurikcopesvulcan.com • Web Site: www.dezurikcopesvulcan.com