Page 407 - APPLIED PROCESS DESIGN FOR CHEMICAL AND PETROCHEMICAL PLANTS, Volume 1, 3rd Edition

Ejectors and Mechanical Vacuum Systems 375

c200 I \ 3. At ejector suction conditions, determine:
a. Pounds/hour of condensable vapor
� 175 b. Pounds/hour of non-condensable gases
.... 150 ( 1) dissolved
Q) \
::,
(/)
(/) (2) injected or carried in process
.... 125
Q)
a. \ (3) formed by reaction
( 4) air inleakage
E 100
- 90 4. Prepare specification sheet, Figure 6-29 and forward
c
Q)
U) 80 \ to manufacturers for recommendation.
4) 70 ' 5. For checking and estimating purposes, follow the
N \
N guides as to the number of stages, utility require-
0
:z 60 \ ments, etc. presented herein.
.8 1.0 1.2
F=Steam Pressure Factor Barometric Condensers
Figure 6-278. Steam pressure factor for Figure 6-27A. By permis- Barometric condensers are direct contact coolers and
sion, Worthington Corp. condensers. They may be counter flow or parallel flow.
Good contact direct cooling is an efficient inexpensive
5 ., design, being considerably cheaper and more efficient
/ / / I/ than indirect surface or tubular coolers.
� 4 ,, I I
<[ / 1v;, 1,/ 6" II
�4� -
o 3 2 - -7
::c / v II y
/
i 2 v / Temperature Approach
<>
-= / �v v /
.. / / 1111 / / When serving vacuum equipment, the temperatures
/
le
::,
s 1.0 ,,
.§ .8 ., ,, ., ,, / II" I / I ., / I are usually set as follows when the non-condensables do
c,
not exceed one percent of the total water vapor being
�
j .6 / � / v / condensed. See Figures 6-20 A, B, C, and D.
2 .5 ., / / ., /
.... .,
<> 4 /
� Terminal Difference, steam temperature corresponding to
20 30 40 60 BO 100 200 300400 600 8001,000 vacuum less outlet water temperature = 5°F.
Capacity , Total I bs. of Mixture per Hour
Figure 6-28A. Ejector size, single stage-typical. By permission, Exit Air or Non-Condensables, temperature to be 5°F
Worthington Corp. higher than inlet water temperature to barometric.
.,; I
..0 \
ct 4
c:i, \ I
::c
..,
"'
.J::. \
(.)
=_3
�
� \
:::, I
"' .., '\,, I
"'
a: 2 !'.... ....... I I
- ...........
c:
.s <,
(.)
:::,
en � -- --- .__ - I
-
0
Figure 6-288. Steam consumption fac- 3 4 5 6 7 8 9 10 II
tor. By permission, Worthington Corp. W� = Pounds of Motive Steam per lb. of Mixture Handled