Boiler house Heat recovery systems
2
Example: The example below considers condensate from three steam systems at different pressures, 20 bar g, 10 bar g and 6 bar g, discharging into a flash vessel designed to operate at 2 bar g. The condensate loads are 1000 kg / h , 2000 kg / h and 4000 kg / h respectively. By consulting the table and entering the relevant data into the boxes below, the total amount of flash steam can be calculated in kg / h. This is multiplied by the 'LP factor' according to the flash vessel pressure to give total volume flow in m 3 / h. Five ' Velocity factors ' are shown: 67 , 138 , 243 , 385 , 560 each of which relate to a 3 m / s take-off velocity for flash vessels FV6, FV8, FV12, FV15, and FV18 respectively. By dividing the 'Total volume' by each of the 'Velocity factors', five take-off velocities are obtained. Choose the smallest flash vessel with a take-off velocity of less than 3 m / s. The example shows an FV8 being the smallest flash vessel with a take-off velocity of 2.7 m / s.
Flash pressure bar g
Trap pressure bar g
0
0.5
1
1.5
2
2.5
3
4
5
6
7
8
9
10
2.8 18
% flash
25 24.5 22.6 21.2 20.0 18.9 18.0 17.2 15.7 14.4 13.3 12.2 11.3 10.4 9.5 24 24.1 22.2 20.7 19.5 18.5 17.6 16.7 15.3 14.0 12.8 11.8 10.8 9.9 9.0 23 23.6 21.7 20.3 19.1 18.0 17.1 16.3 14.8 13.5 12.3 11.3 10.3 9.4 8.5 22 23.2 21.3 19.8 18.6 17.6 16.6 15.8 14.3 13.0 11.8 10.8 9.8 8.9 8.0 21 22.7 20.8 19.3 18.1 17.1 16.1 15.3 13.8 12.5 11.3 10.3 9.3 8.4 7.5 20 22.2 20.3 18.8 17.6 16.6 15.6 14.8 13.3 12.0 10.8 9.7 8.7 7.8 6.9 19 21.7 19.8 18.3 17.1 16.0 15.1 14.2 12.7 11.4 10.2 9.2 8.2 7.2 6.4 18 21.2 19.3 17.8 16.6 15.5 14.5 13.7 12.2 10.8 9.7 8.6 7.6 6.7 5.8 17 20.6 18.7 17.2 16.0 14.9 14.0 13.1 11.6 10.3 9.1 8.0 7.0 6.1 5.2 16 20.1 18.2 16.7 15.4 14.3 13.4 12.5 11.0 9.7 8.5 7.4 6.4 5.4 4.5 15 19.5 17.6 16.1 14.8 13.7 12.8 11.9 10.4 9.0 7.8 6.7 5.7 4.8 3.9 14 18.9 16.9 15.4 14.2 13.1 12.1 11.2 9.7 8.4 7.1 6.0 5.0 4.1 3.2 13 18.2 16.3 14.8 13.5 12.4 11.4 10.6 9.0 7.6 6.4 5.3 4.3 3.3 2.4 12 17.5 15.6 14.1 12.8 11.7 10.7 9.8 8.3 6.9 5.7 4.6 3.5 2.6 1.7 11 16.8 14.8 13.3 12.0 10.9 10.0 9.1 7.5 6.1 4.9 3.8 2.7 1.8 0.9 10 16.1 14.1 12.5 11.3 10.1 9.2 8.3 6.7 5.3 4.1 2.9 1.9 0.9 - 9 15.2 13.2 11.7 10.4 9.3 8.3 7.4 5.8 4.4 3.2 2.0 1.0 - - 8 14.4 12.3 10.8 9.5 8.4 7.4 6.5 4.9 3.5 2.2 1.1 - - - 7 13.4 11.4 9.8 8.5 7.4 6.4 5.4 3.8 2.4 1.2 - - - - 6 12.3 10.3 8.7 7.4 6.3 5.2 4.3 2.7 1.3 - - - - - 5 11.2 9.1 7.5 6.2 5.0 4.0 3.1 1.4 - - - - - - 4 9.8 7.7 6.1 4.8 3.6 2.6 1.7 - - - - - - - 3 8.3 6.2 4.5 3.2 2.0 0.9 - - - - - - - - 2 6.3 4.2 2.6 1.2 - - - - - - - - - - 1 3.8 1.7 - - - - - - - - - - - -
LP Factor = 1.673 1.149 0.881 0.714 0.603 0.522 0.461 0.374 0.315 0.272 0.240 0.215 0.194 0.177
AI-P404-12 AB Issue 3
Page 2 of 5
Sizing A Flash Vessel On Up To Three Trap Pressures
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