Gas velocity 1.2 1.2 1.2 1.2 1.3 1.3 1.3 1.3 1.31.31.3 1.3 0.2 0.2 0.2 0.2 Emiss
ID: 1712023 • Letter: G
Question
Gas velocity 1.2 1.2 1.2 1.2 1.3 1.3 1.3 1.3 1.31.31.3 1.3 0.2 0.2 0.2 0.2 Emission Gas velocity 1.2 1.9 0.9 1.2 1.6 1.8 0.9 0.9 1.3 1.7 0.1 0.1 0.10.1 1.1.0.2 1.0 0.9 1.0 1.1 0.8 0.6 0.9 0.9 Emission 1.1 0.70.81.0 1. 0.8 0.91.4 1.0 0.71.01.0 0.9 0.9.2 1.5 .0 19 6'-0" To main flue 2'-0" -0 Average gas velocity-39 fus Average emission per unit area = 1.2 lb/ft2-hr Citation From No. 2 I.D. fan From No. 1 I.D. fan FIGURE 4.3 Measured velocities and particle mass flow rates (velocity concentration) in a complex duct. The valuesi shown are the ratio of the observed value to the average value for the whole duct. For example, near the bend, where the velocity is shown as 1.2, the measured velocity was 12-39 ft/s 47 ft/s 14.3 m/s [2]Explanation / Answer
In the above figure we need to calculate total volume flow rate, but given that two sections and distance between them are 36'. Given that velocities and emission values which can physically idetified that the values are different but if we closely observe that sum of all the values are constant at both the sections.
sum of all the velocities at first section = 1.2x4 + 1.3x8 + 0.2x4 = 16
Sum of all the velocities at end section = 1.1x7 + 1.2+ 1.0x3 + 0.8 + 0.6 + 0.9x3 = 16
simillarly
Sum of all the emisson values at first section = 1.1x2 + 1.2x2 + 1.3 + 1.6 + 1.7 + 1.8 + 1.9 + 0.9x3 + 0.1x4 = 16
Sum of all the emisson values at first section = 1.1x2 + 1.0x4 + 0.9x3+ 0.8x2 + 0.7x2 + 1.2 + 1.5 +1.4 = 16
So from the above, consider any section
let consider end section
total; velocity = 16
given average gas velocity = 39 ft/s
Total velocity = 16x39 = 624 ft/s = 190.19 m/s
Area = 8' x 6' = 2.4384 x 1.8288 = 4.459 m2
Total volumetric flow rate = velocity x Area = 190.19 x 4.459 = 848.123 m3/s
given average emission per unit area = 1.2 lb/ft2-hr
Total mass emission rate = total emission value x average emission per unit area x area = 16x 1.2x 8x6
= 921.6 lb/hr = (921.6/3600) lb/s = 0.256 lb/s = 0.116 kg/s
The required answers are
Total volumetric flow rate = 848.123 m3/s
Total mass emission rate = 0.116 kg/s
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