Control systems Desuperheaters
4
Detailed example (continued) The datasheet generated by the program for this example is as follows: Spirax Sarco Venturi Type Desuperheater Data Sheet
v 1.4
1 Client :
Spirax-Sarco Limited
Client Project Ref : Plant Location : Equip. Item No. :
2 Client's Ref :
EXAMPLE CALCULATION
3 Spirax Sarco Ref :
VTD01582
4 Description :
Size 6 Venturi Type Desuperheater
No. OFF : Operation : Serial No. :
1
5 Unit Ref :
VTD150 °CS6F0 DE-VTDSDSO
6 Drawing No. :
7 Unit Size :
6
INLET CONDITIONS
CONDITIONS UPSTREAM OF LET-DOWN VALVE
8
Case 1
Case 2
Case 3
9 Flowrate (kg/hr) 10 Pressure (bar g) 11 Temperature ( °C)
5000 2.302 179.7
3000 2.108 179.2
1000 2.012 178.9
Case 1
Case 2
Case 3
2
1
10
10
10
200
200
200
12 13
COOLING MEDIUM
Case 1
Case 2
Case 3
14 Flowrate (kg/hr) 15 Pressure (bar g) 16 Temperature ( °C)
193.5
116.1
38.7 2.13
4
5.34
3.2
95
95
95
17 Medium -
Water
18 19
DISCHARGE CONDITIONS
Case 1
Case 2
Case 3
4.8 19
20 Pressure (bar g) 21 Temperature ( °C) 22 Flowrate (kg/hr)
2
2
2
3
136.7
136.7 3116.1
136.7
5193.5
1038.7
23 24
MATERIALS OF CONSTRUCTION
Flanges Gaskets
Carbon Steel ASTM A 105
25 Main Body 26 Inner Nozzle 27 Inner Venturi
Carbon Steel ASTM A 106 Grade B Stainless Steel BS 970 S11/13 Stainless Steel BS 970 S11/13
Soft Copper
Inner Body Main Venturi
Carbon Steel ASTM A350 LF2 C.Steel BS 1501-151/161-430A/B
28 29 30
MECHANICAL DESIGN
Steam Water
CONNECTION DETAILS
Side
Side
Size
Rating 300 LB 300 LB 300 LB
31 Max.Design Pressure (bar g) 32 Max. Design Temperature ( °C) 33 Internal Corrosion Allowance (mm)
15
15
Inlet Steam
6
220
220
Discharge Steam 6 Cooling Medium 1
1.5
1.5
34 Mechanical Design Code
ASME B31.3
Flange Type
ASME B16.5 Slip-On
35 Welding Standard
To Code
36 External Surface Finish
High Temp. Silicone Aluminium
37 Weight (kg)
68
38 39 40 41 42 43 44
DIMENSIONS
A (" NB)
6
B (mm) 178 C (mm) 127 D (mm) 533 E (mm) 660
Note: Letters refer to Drawing
0 Issued for sizing only
PDA
08/01/2010
Rev Description
By
Date
Checked
Date
A Spirax Sarco Size 6 venturi type desuperheater has been selected. It can be seen from the 'Cooling Medium' section that the maximum cooling water pressure required is 35 psi g (2.41 bar g) consequently a water booster pump should also be installed (as the cooling water is only available at 75 psi g (5.17 bar g). The program has calculated a steam pressure drop across the desuperheater of 4.4 psi g (0.303 bar g) (maximum). As there is a pressure reducing valve installed, the program has automatically added this pressure drop to the desuperheater inlet pressure to 'compensate' for the pressure drop. This will ensure that the outlet pressure from the desuperheater is 30 psi g (2.07 bar g). The datasheet therefore shows the correct pressures and flowrates for sizing both the pressure reducing valve and the water control valve.
TI-P475-06 CTLS Issue 4
Page 9 of 12
Desuperheater Online Program Sizing Guidance
Powered by FlippingBook