Page 410 - APPLIED PROCESS DESIGN FOR CHEMICAL AND PETROCHEMICAL PLANTS, Volume 1, 3rd Edition

378 Applied Process Design for Chemical and Petrochemical Plants

Table 6-11 Table 6-13
Air Density Table Temperature-Pressure-Volume of Saturated Water
Vapor Over Ice
.. -
Density. Lbs./Hr./CFM at
Temp. °F. Lbs./cu. ft. 30" Hg. Abs. Specific
ABSOLUTE PRESSURES Volume
30 . 0.08105 4.86 Temp. ------ Cu. Ft.
40 . 0.07943 4.76 •F. Inches Hg M.M.Hg Microns Per Lb.
50 . 0.07785 4.66
60 . 0.07635 4.58 32 0.1803 4.580 4580 3,306
70 . 0.07493 4.50 30 0.1645 4.178 4178 3,609
80 . 0.07355 4.42 25 0.1303 3.310 3310 4,508
90 . 0.07225 4.34 20 0.1028 2.611 2611 5,658
100 . 0.07095 4.25
110 · 0.06966 4.18 15 0.0806 2.047 2047 7,140
120 . 0.06845 4.10 10 0.0629 1.598 1598 9,050
130 . 0.06730 4.04 5 0.0489 1.242 1242 11,530
140 . 0.06617 3.97 0 0.0377 0.958 958 14,770
150 . 0.06510 3.91
-5 0.0289 0.734 734 19,040
-10 0.0220 0.559 559 24,670
-15 0.0167 0.424 424 32,100
-20 0.0126 0.320 320 42,200
Table 6-12
Gas Constants -25 0.0094 0.239 239 55,800
-30
74,100
0.180
0.0071
180
-35 0.0051 0.130 130 99,300
PV = WRT R = 1544/Molecular Weight -40 0.0038 0.097 97 133,900
I
For Use With Units Of:
Cubic Feet, Lbs./Sq. Ft. Abs., R., Pounds Values obtained from Keenan & Keyes-"Thermodynamic
0
Properties of Steam". John Wiley & Sons, 1936, by permission.
Mol. Gas
Gas or Vapor Formula Weight Constant, R
Hydrogen ............... I-h 2 772 suspended solids and slurries. Sizes range from l'2 inch to
Carbon Monoxide ........ co 28 55.l 24 inches. The ejectors are usually used in pumping air or
Oxygen ................. 02 32 48.3 gases while the eductors are used in pumping liquids.
Methane ................ CH. 16 96.5
Ethylene ................ C2H• 28 55.1
Nitrogen ................ N2 28 55.1
Ammonia ............... NH a 17 90.8 Steam Jet Thermocompressors
Carbon Dioxide ...... ' ... C02 44 35.l
Steam (Water Vapor) ..... H20 18 85.8
Sulfur Dioxide ........... S02 64 24.1 Steam jet thermocompressors or steam boosters are
Air ..................... ... ' 29 53.3 used to boost or raise the pressure of low pressure steam
to a pressure intermediate between this and the pressure
of the motive high pressure steam. These are useful and
economical when the steam balance allows the use of the
Air temperature leaving barometric = 85 + 5 = 90°F
necessary pressure levels. The reuse of exhaust steam
from turbines is frequently encountered. The principle of
8500 (1000)
en.,[ cooling water required = = 556 operation is the same as for other ejectors. The position
(30.6) (500)
of the nozzle with respect to the diffuser is critical, and
Water Jet Ejectors care must be used to properly position all gaskets, etc.
The thermal efficiency is high as the only heat loss is due
Ejectors using water as the motive fluid are designed to radiation [5].
for reasonable non-condensable loads together with large
condensable flows. Water pressures as low as 10-20 psig Ejector Control
are usable, while pressures of 40 psig and higher will
maintain a vacuum of 1-4 inches of Hg absolute in a sin- Ejectors do not respond to wide fluctuations in operat-
gle stage unit [1]. Combinations of water and steam ejec- ing variables. Therefore, control of these systems must
tors are used to efficiently handle a wide variety of vacu- necessarily be through narrow ranges as contrasted to the
um situations. The water ejector serves to condense the usual control of most other equipment.
steam from the steam ejector. For the single stage ejector, the motive steam flow can-
\,\Tater ejectors and water jet eductors are also used for not be decreased below critical flow in the diffuser [2],
mixing liquids, lifting liquids, and pumping and mixing (Figure 6-30). Units are usually designed for stable opera-