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Control systems Desuperheaters
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.
Internal nozzle
Internal diffuser
Main diffuser
Steam flow
Seals
Cooling water
Application - Suitable for most general plant applications, except where high turndowns on cooling water are required. - Flow turndowns between 3:1 and 10:1 depending on conditions.
4.8 4
Mechanical design temperature and flange rating <371 °C (<700 °F)
ASME 150, ASME 300, ASME 600 + PN16, PN25, PN40 Slip-on (Weld neck optional)
371 - 427 °C (700 - 800 °F) 424 - 570 °C (795 - 1058 °F)
ASME 150, ASME 300, ASME 600 + PN16, PN25, PN40 Weld neck (Slip-on N/A)
ASME 300, ASME 600, ASME 900, ASME 1500 + PN10, PN16, PN25, PN40, PN63 and PN100 Weld neck (Slip-on N/A)
Materials
Mechanical design temperature above 427 °C (800 °F) up to and including 570 °C (1058 °F)
Mechanical design temperature up to and including 427 °C (800 °F)
Component
Sizes 1 to 2: Size 3 and above: Sizes 1 to 2: Size 3 and above: Sizes 1 to 2: Size 3 and above:
ASTM A350 LF2N ASTM A106 Grade B ASTM A350 LF2N ASTM A106 Grade B ASTM A350 LF2N ASTM A105N
Sizes 1 to 2: Size 3 and above: Sizes 1 to 2: Size 3 and above:
ASTM A182 F11 ASTM A335 P11 ASTM A182 F11 ASTM A335 P11
Shell
Water branch
Flanges
ASTM A182 F11
Nozzle
ASTM A182 F316L
ASTM A182 F11
Sizes 1 to 2: Size 3 and above: Sizes 1 to 2: Size 3 and above: Sizes 1 to 4: Sizes 6 and 8: Size 10: Size 12 and above:
Not applicable ASTM A182 F316L Not applicable ASTM A350 LF2N
Sizes 1 to 2: Size 3 and above: Sizes 1 to 2: Size 3 and above:
Not applicable ASTM A182 F11 Not applicable ASTM A182 F11
Internal diffuser
Internal housing
ASTM A350 LF2N ASTM A240 / ASTM A312 316L BS EN 10130:2006 DC01 ASTM A516 Gr70
Sizes 1 to 4: Sizes 6 and above:
ASTM A182 F11 ASTM A387 Gr11
Main diffuser
Internal seals
Soft copper
Soft copper
TI-P475-01 TES Issue 5
Page 4 of 9
Direct Contact Desuperheaters
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