Note
Neither Emerson, Emerson Process Management, nor any of their affiliated entities assumes responsibility for the selection, use and maintenance of any product. Responsibility for the selection, use, and maintenance of any product remains with the purchaser and end-user.

• Design DMA—A simple mechanically atomized desuperheater with single or multiple, fixed-geometry spray nozzles is intended for applications with nearly constant load. The Design DMA is installed through a flanged connection on the side of a DN150 (NPS 6) or larger pipeline. Maximum unit CV is 3.8.
• Design DMA/AF—A variable-geometry, mechanically atomized, back-pressure-activated desuperheater with one, two, or three spray nozzles is designed for applications requiring control over moderate load fluctuations. The Design DMA/AF desuperheater (figure 2) is installed through a flanged connection on the side of a DN200 (NPS 8) or larger pipeline. Maximum unit CV is 15.0.

• Design DMA/AF-HTC— The Design DMA/AF-HTC is functionally equivalent to the Design DMA/AF, however it is structurally suited for severe applications. The most common applications include boiler interstage attemperation, where the desuperheater is exposed to high thermal cycling and stress, high steam velocities and flow induced vibration. In addition to this specific application, the Design DMA/AF-HTC is suitable for other severe desuperheating application environments. The Design DMA/AF-HTC uses a forged construction optimized to move weld joints away from high stress regions. The Design DMA/AF-HTC differs from other desuperheaters whereas it requires a minimum mounting ID of NPS 4. Typically this requires using a long welding neck flange for the mounting flange.

The desuperheater design incorporates an integral thermal liner inside the desuperheater body pipe. This minimizes the potential for thermal shock when cool water is introduced to the unit that is already heated to the operating steam temperature.
The nozzle mount for the Design DMA/AF-HTC is engineered to minimize the potential for excitation due to vortex shedding and flow induced vibration. The Design DMA/AF-HTC desuperheater (figure 5) is installed through a flanged connection on a DN200 (NPS 8) or larger pipeline. Maximum unit CV is 15.0.

• Design DSA—The Design DSA desuperheater uses high-pressure steam for rapid and complete atomization of spraywater in low-velocity steam lines. This desuperheater (figure 3) is installed through a flanged connection on a DN200 (NPS 8) or larger pipeline. This desuperheater is intended for applications requiring high rangeability. Maximum unit CV is 9.97.
• Design DVI—This desuperheater injects spraywater in the outlet of the venturi section, assuring excellent mixing and rapid atomization. The Design DVI desuperheater (figure 6) is easily installed between flanges in DN25 through DN600 (NPS 1 through 24) steam lines. There are no moving parts, and the water injection pattern provides rapid and thorough cooling. It is intended for applications with moderate load changes and low-velocity steam. Maximum unit CV is 9.48.
• Design TBX-T—The Design TBX-T desuperheater incorporates a spraywater manifold of variable geometry Type AF nozzles that produce an optimized spray pattern over a wide operating range. These nozzles are strategically placed to achieve optimal mixing and quick vaporization at all flowing conditions (see figure 4).

The Design TBX-T desuperheater can be configured with a pressure reducing valve (PRV) immediately upstream, with an integral diffuser, or as a standalone device.

Available Types

Design ■DMA, ■DMA/AF, ■DMA/AF-HTC, ■DSA, ■DVI, and ■TBX-T(see the Available Desuperheater Types section for descriptions)

Connections

See table 1

Maximum Pressure Rating(1)

Consistent with applicable pressure-temperature ratings (as shown in table 1) per ASME B16.34

Inherent Rangeability

Up to 50:1. The ratio of maximum to minimum controllable Cv is dependent upon the available water pressure differential

Spray Water Pressure Required(2)

3.5 to 35 bar (50 to 500 psi) greater than steam line pressure

Atomizing Steam (Design DSA)

Atomizing steam should be 2.0 times the pressure of the steam to be desuperheated. Amount of atomizing steam will be 10% of maximum spraywater flow

Maximum Unit CV (for Spraywater Flow)

Design DMA: 3.8
Design DMA/AF: 15.0
Design DMA/AF-HTC: 15.0
Design DSA: 9.97
Design DVI: 9.48
Design TBX-T: Contact your Emerson Process Management sales office

Construction Materials

Desuperheater Body (all Designs except DMA/AF-HTC): ■ Carbon steel, ■Chrome-moly alloy steel (F22), or ■300 series stainless steel
Desuperheater Body (Design DMA/AF-HTC): ■Chrome-moly alloy steel (F22, F91)
Nozzle Material Design DMA: ■ 303,■ 316, or, ■410 stainless steel
Design DMA/AF, DMA/AF-HTC, TBX-T, and DSA: ■410 stainless steel
Design DVI: ■303 or ■316 stainless steel or ■ F22 venturi with drilled hole

Note
Neither Emerson, Emerson Process Management, nor any of their affiliated entities assumes responsibility for the selection, use and maintenance of any product. Responsibility for the selection, use, and maintenance of any product remains with the purchaser and end-user.