Geoscience Reference
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Calculate the collection efficiency of the electrostatic precipitator using the Deutsch-Anderson
equation. The volumetric flow rate (
Q
) through a passage is one-third of the total volumetric flow
rate:
Q
= 4000/(3 × 60) = 22.22 acfs
−
wA
Q
=−
−×
288 04
22 22
.
=
η= −
1
exp
1
exp
0 9944
.
=
99 44
.
%
.
What is the collection efficiency of the electrostatic precipitator if one duct is fed 50% of the gas
and the others 25% each? The collection surface area per duct remains the same. First calculate the
volumetric flow rate of gas through the duct in acfs:
Q
= 4000/(2 × 60) = 33.33 acfs
and then calculate the collection efficiency of the duct with 50% of gas:
(
−×
288 004
33 33
.
=
η
1
== −
1
exp
0 9684
.
=
96 84
.
%
.
To calculate the collection efficiency of the duct with 25% of gas flow, first calculate the volumetric
flow rate of gas through the duct in actual cubic feet per second (acfs):
Q
= 4000/(4 × 60) = 16.67 acfs
and then calculate the collection efficiency (η
2
) of the duct with 25% of gas:
(
−×
288 004
16 67
.
=
η
1
== −
1
exp
0 9990
.
=
99 90
.
%
.
Now calculate the new overall collection efficiency. The equation becomes
η
t
= (0.5 × η
1
) + (2 × 0.25 × η
2
) = (0.5 × 96.84) + (2 × 0.25 × 99.90) = 98.37%
■
EX AMPLE 17.10
Problem:
A vendor has compiled fractional efficiency curves describing the performance of a spe-
cific model of an electrostatic precipitator. Although these curves are not available, the cut diameter
is known. The vendor claims that this particular model will perform with a given efficiency under
particular operating conditions. Verify this claim and make certain the effluent loading does not
exceed the standard set by USEPA (1984b, p. 75).
Given:
Plate-to-plate spacing = 10 in.
Cut diameter = 0.9 µm
Collection efficiency claimed by the vendor = 98%
Inlet loading = 14 grains/ft
3
USEPA standard for the outlet loading = 0.2 grains/ft
3
(maximum)
Particle size distribution as given in Table 17.6
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