Page 279 - APPLIED PROCESS DESIGN FOR CHEMICAL AND PETROCHEMICAL PLANTS, Volume 1, 3rd Edition

r- Mechanical Separations 249

tern, because the wire style, size, and material also affect the
2. value. For pressures below 30 psig, k = 0.35 avg., then
above 30 psig, k value decreases with pressure with an

Certain values have been found satisfactory for estimating
I I I approximate value of 0.30 at 250 psig and 0.275 at 800 psig.
systems described in Table 4-10 and Table 4-11.
I For conditions of high liquid loading, use caution in
1. 0 design. Use the high velocities for very fine mist to
.4
.9 0 I remove the small particles, and use two mesh pads in
.8 0 , series with the second mesh operating at a lower velocity
.7 0 I a Lo remove the larger drops re-entrained from the first
.4
.60 mesh. Systems involving high viscosity fluids should be
/��t.3 checked with the various manufacturers for their case his-
.5 0 tory experience. Lower k values are used for systems with
� f �P�2 high vacuum, high viscosity liquids, low surface tension
.40 ,
I
! i Table 4-10
.30
6' "k" Values for Knitted Mesh
::z::"' /Ji.
E ! � Bottom of mesh at least 12 inches above liquid surface
; Service Conditions "k" General Type Mesh
.20
"'t" Clean fluids, moderate 0.35 to 0.36 Standard
� ' liquid load, fits 90% of 0.35 High Efficiency
� ' process situations 0.25 Very High Efficiency
ON High viscosity, dirty 0.40 Low density or
I suspended solids Herringbone, high
(/) ' through-put
Q.J
s: .4�- j Vacuum operations:
� .10 2" Hg. abs. 0.20 Standard or
I� 'II 16" Hg. abs. 0.27 High Efficiency
g; .09 II II Corrosive Chemical 0.21 Plastic coated wire,
� .08 or plastic strand
II II
� .D7 II II Compiled from various manufacturer's published data. Note: k values
� .06 II u for estimating pm·poses, not final design unless verified by manufactur-
(/)
w er. Unless stated, all values based on stainless steel wire.
a: ,
c, .05 II�
TYPEi 1i r Variation of k with Disengaging Height*
.04 Table 4-11

.03 Disengaging Height Above Mesh, Inches Allowable k Value

�� '//;' 4 0.15
3 .......•.................. 0.12
0.22
.02 TYPE' 5 0.19
6
I 7 ........••....•........... 0.25
I II
I ' I 8 0.29
9
0.32
10
11 0.35
0.38
!2 0.40
13 0.42
0.2 0.3 0.4 0.5 0.6 0.7 14 0.43
K-factor, V/[(pl - pv}lpv]"' ft/sec (x 0.3048 = m/sec)
*By permission, 0. H. York, Reference (21).
Note: Values based on 12 lb/cu ft wire mesh. Design practice normally
Figure 4-17C. Pressure drop vs K-factor for standard York-Vane mist does not exceed k of 0.4 even for higher disengaging height.
eliminators, air-water system. By permission, Otto H. York Co., Inc.