Entrainment in Oil Absorbers F. ,4.ASHRAF,~ T. L. CUBBAGE,~ AND R. L. HUNTINGTON University of Oklahoma, Norman, Okla.
Carey ( 1 ) offers another equation which is a simplification of Souders and Brown’s equation and should give substantially the same result, except for high-pressure fractionating equipment or whenever the value of dz is sufficiently large in relation to d, to have an effect on the numerical value of the expression (dl - d2):
U = K (liquid density)l/z FIGURE 1. PHOTOGRAPH OF THE THREE LABORATORY TOWERS
E
NTRAISMENT, or the mechanical carrying of liquid droplets from one tray to another has long been recognized as a detriment to the efficiency of all types of bubble-plate towers. Impairment of color is not so important in oil absorbers as i t is in fractionating columns, where entrainment even to a small degree may throw certain products off specification. Loss of absorption oil, however, from oil absorbers into the dry residue gas not only causes an added cost to the manufacturer of natural gasoline but also lowers the value of such gas when used as a raw product for carbon black manufacture. When residue gas is blown into the air in large quantities] entrained oil creates a hazard and a nuisance as it settles on surrounding dwellings and growing crops. Entrainment has been partially solved, in an empirical manner, by a n increase in the distance between plates and by t h e installation of various types of mist extractors located immediately below each plate and in the top of the tower several feet above the top tray. There has also been a trend toward larger down-spouts so as to prevent the possibility of excessive liquid submergence on each tray when higher rates of reflux or liquid absorbent might be used. These improve ments have given the towers a wider range of liquid and vapor capacities, but have not given the manufacturers of such equipment the required quantitative data so badly needed for the intelligent design of bubble towers. Souders and Brown (6) have developed a relationship between the allowable mass velocity of a rising stream of vapor and the densities of liquid droplets and vapor fluid. By equating the upward force given to the droplet to the downward pull of gravity, the following expression has been obtained by these investigators :
w
=
C[d*(dl
-
dJ11’2
where W = mass velocity of vapor C = a constant dz = density of fluid or vapor dl = density of liquid droplets 1
3
Present address, Anglo-Persian Oil Company, Teheran, Persia. Present addreas, Phillips Petroleum Company, Bartlesville, Okla.
vapor density where U = linear velocity, ft./sec. K = a constant Chillas and Weir @) have obtained some quantitative data with air and water and have shown how entrainment is reduced by means of a mist extractor. Holbrook and Baker (3) have recently reported results of a laboratory investigation in which steam and salt water were used in a bubble-plate tower.
EXPERIMENTAL WORK The writers have realized the need of quantitative data showing the relationships between the numerous variables involved, such as tray spacing, gas and liquid densities, velocities, surface tension, ratio of liquid to vapor, liquid submergence] chimney and bubble-cap design, etc., and have therefore set up and operated two small laboratory columns and a semi-commercial tower, shown in Figure 1: To the left of the window is a standard 2-inch wrought-iron pipe column, equipped with a bubble cap at the base and three flanges, 16,20, and 24 inches, respectively, above the bottom tray. A movable tray assembly is bolted in place at the 20-inch spacing. To the right of the window is a small glass column, ls/lO inches i. d., and in the right foreground is the semi-commercial fractionating column with its overflow weir and one of its removable trays standing on the floor near by. The glass column has a bubble cap at the base and a movable tray which can be manipulated from overhead. The 121/r inch i. d. semi-commercial tower was primarily designed for studies in fractionation, but, since it has not been insulated as yet, it is being used temporarily as an absorber. Compressed air, which is piped to the tower through a 2-inch pipe, is available in sufficient quantities for linear velocities up t o 21/r feet per second. This column is equipped with three removable trays; the spacing between them can be varied by changing the length of the downspout and spacer nip les. Each tray has a rim which provides an annular space of agout 1/4 inch between the rim and the inside wall of the tower into which asbestos rope (soaked with sodium silicate) can be tightly packed. Figure 2 shows the design of the 2-inch iron tower and Figure 3 the details of the glass column. Table I gives the various dimensions of the trays, caps, chimneys, etc., for the three laboratory columns, and Table I1 the physical properties of the liquids and gases used in the different columns. In order t o duplicate as closely as possible conditions in the top of an absorber, kerosene was chosen as the liquid and a dry natural gas and air as the vapor mediums. I.068
i N D ENGINEERING CHEMISTRY
INDUSTK[ \L
October, 1934
'rABI,E; I.
1069
DIMEXBIOSS OF CoLmssfi IAENOTH FROM
I D.
so.
OF
BOTTOM
OF
TOWER Inches
CHIMNEYS
CHIMNEY
I. D . Inches
OF
0. D.
PLATE Inches
Inches
aq ' I
UPTAKE CHIMNEY
1 1 2
Glass column 2-in. iron tower I2l/n-in. iron towern
2
'/2
1 2s/a
0.114 0.14 0.05
aa/4
21/4
BUBBLE C A P
NO.
COLTJNN
SEAPE
B U B B LCAPS ~ I. D. 0. D. Inches Inches
OF CAPS
SLors Number
Length Inch
Width Inch
Glass 1 B/S 12 9/10 l/sz Round If3 2-in. 1 a Round 1 '/32 'la 32 12I/z-in. 2 35,'s 1 8/16 Square a Commercial absorber 7 X 30 feet. ten trags, 22-inch spacing; 6 feet from top tray t o top of absorber. b Ratio of the cross sec'tional area oi'the uptake chimney to that of the tower. c From t h e top of the slots to the surface of the liquid.
..
TABLE11. PROPERTIES OF MATERIAL PRDWJRE LIQUID COLUMN
OR
Laboratory 7-ft. i. d . commercial
GAB
Kerosene Natural ga6 .4ir Dry residue gas Gas oil
AT 14.2
LB.
ABS.
SURFACE VISCOSITY TENSION Ar
AT
70' F. 70OF. Lb./cu. f t . Centzpoisea D y n e s / c m . DEN3ITY
50.5 0.0450 0.0734 0.05 52.2
1.95 ,.
29.0
.. ..
,.
4 57
-.==
FIGURE 2.
lXHAUST
OUTLET
and Figures 4 to 10. As might be expected, the data obtained from the small columns do not give results which are as comparable with commercial towers as the runs made on the 12l/*-inch i. d. tower; moreover, i t is inconsistent to attempt to compare laboratory data with overhead entrainment from commercial absorbers since the space above the top tray in an absorber is usually from 4 to 6 feet in height.
DATAFROM %INCH IRON PIPE COLUMN SHOWING EFFECT PRESSURE ON EXTRAINJIENT. Figure 4 shows the relationship between entrainment and mass velocity for three different operating pressures with a tray spacing of 24 inches. Data from the same set of runs have been plotted in Figure 5 giving the entrainment in pounds per hour per square foot of cross-sectional area of the tower vs. linear velocity. The two graphs show that more gas can be processed a t higher pressures for the same entrainment but that the permissible linear velocity falls off with increasing operating pressures because of the bouyancy of the denser gas surrounding the liquid droplets. OF
I
$++L
1
0.255 0.149 0.0975
FIGURE 3. GLASSCOLUMN SET-UPFOR GRAWMETRIC DETERRIINATION O F ENTRAINMENT
GAS
GAS SUPPLY
Inches 2.0 2.5 1.0 12 Two mist extractors, 4 feet above top tray. sr/1ao l/l
30:9
z=i t
T
QENCEC
DISCUS~ION OF RESULTS The results from the several laboratory columns, as well as actual operating data from some commercial absorbers in the Oklahoma City field are shown in Tables I11 and IV
A
&-4I
LIQUID sUBYER.
kerosene was colored during the run gave a measure of the amount of entrainment,
LABORATORY GLASSCOLUMN.The small glass column was operated in order to observe the froth levels and the effective lengths of the slots, as well as to measure the entrainment with different tray spacings. Since the ercentage of kerosene which was thrown from the lower tray to t f e upper was never more than 5 per cent, the liquid level on the lower tray remained substantially constant. The upper tray was filled with glass wool, and the vapor was made to pass through the glass wool by means of a reflector cap. The increase in weight of the glass wool gave a measure of the entrainment. Cotton was fist tried but proved ineffective since it was not readily wetted by an oil mist. TWO-INCH IROXPIPE COLUMN.This column was designed for the study of pressures from atmospheric up to 100 pounds per square inch gage. The method of operation was similar to that of the glass column. FRACTIONATINQ COLUMN, 121/$ INCHES I. D. In order t o obtain quantitative data which would more nearly approach that of commercial towers, the semi-commercial column shown in Figure 1 was connected with an air line. The down-spouts were plugged, kerosene highly colored with a nonvolatile oilsoluble purple dye was put on the lower tray, and clear kerosene was poured onto the upper tray. The degree t o which the clear
~
SLOTARDA TOWERAREA
Total area Sa. i n .
OIL OVERFLOW
STANDhRD 2-INCH WROUGHT-IRON P I P E COLUMN
1070
INDUSTRIAL AND ENGINEERING CHEMISTRY
Figure 7 shows the effect of plate spacing from data obtained on the glass column. T h e c u r v e s are similar to those in Figure 6. S U B M E R G E X C EFROTH ,
4.0 4
630
3.
6
Y
3
Vol. 26, No. 10
>a 1
H E I G H T , A N D PRESSURE DROPS. Data from the glass a eU column are given in Figure 8 \ l 2 showing the height of froth ,-20 z I= $2 and the effective length of the 5 u1 Y L slots a t various linear velocizz E U 55 ties. Daube (7) b u b b l e d 5 various gases through a soda 5 I. LO ash solution and found that the height of the froth produced was a function of linear velocity and not mass velocity. From a theoretical standpoint one would expect MASS VELOCITY, */HR./S.FT. PLATE SPACING, INCHES t h e k i n e t i c energy of the FIGURE 4. ENTRAINMENT us. MASS bubbles making up the froth VELOCITY FOR LINESOF CONSTANT F'IGURE 5. E ~ T R A I N M E N TUs. us. PLATE SPACING AT ATPRESSURE AND A KEROSENE-NATU-LINEARVELOCITY AT DTFMOSPHERIC pREssURE FOR to be a controlling factor. Of RAL GASSYSTEM FERENT OPERATING P R E S A KEROSENE-NATURAL course, the mass of a bubble A 0 GAS SYSTEM IN THE may be largely that of the NATURAL GAS SYSTEM '-INCH IRON PrpE coL- l i q u i d film surrounding the UMN vapor or gas. However the data for air fall slightly higher than for the gas. Both froth curves are linear with respect to the linear velocity of the vapor. The effect of liquid submergence on entrainment and pressure drop through the plate is shown in Figure 9 and Table IV. I Figure 10 gives a general idea of the comne2 parative performance of the three laboratory s* c o l u m n s and a commercial absorber in the 06b Oklahoma City oil field. 2 After allowing for the greater density of the ""5 air, as compared with that of the gas, i t is readily w seen that the entrainment is higher in the 12l/20.2 E i n c h c o l u m n than in the small laboratory columns. This is probably due to the fact that o b the ratio of the slot area to the cross-sectional tower area is less in the 121/2-inch tower than in FIGURE 8. VARIATION OF HEIGHT OF the small columns. It was observed that the F~~~ AND EPP~CTIVE LENGTH PLATE SPACING IN INCHES SLOTS AT VARIOUS LINEAR VELOCITIES degree of atomization of liquid droplets was FIGURE7. ENTRAINMENT us. Height of froth = top of slots to top of froth; pLATE SPACING FOR L~~~~ OF effective length of slot = top of dead h q m d t
a
r
:
LINEAR VELocIm AT THE
to top of slot.
ATMOSPHERIC PRESSURE IN GLASSCOLUMN
Table 111includes the values of C in Souders and Brown's equation and of K in Carey's equation; these values were calculated from the experimental data. EFFECT OF PLATE SPACINO. Figure 6 shows a cross plot of data obtained on the 2-inch iron pipe column a t atmospheric pressure, giving the relationship between entrainment and plate spacing for lines of constant linear velocity. These curves show that a certain amount of entrainment takes place regardless of the distance between plates, entrainment which is probably due to the suspension of very minute liquid droplets in the gas stream. At lesser spacings a large part of the entrainment is the result of splashing of comparatively large drops, caused by the jetting action of the gas.
007
5
0.06
I Os5
;
:
00
oo2
oo,
FIGURE9. EFFECTOF LIQUID SUBMERGENCE ON ENTRAINMENT AND PRESSURE DROP THROUGH A BUBBLE C A P D $ ~ ; o ; ~ ~ ~~ ~~ ; ~ ~ & ~ l : " ' i ~ c ~ ~ velocity, 1 3 feet per second
D LINEAR' VELOCITY,
ri.Aec.
FIGURE10. ENTRAINMENT us. LINEARVFLOCITY ENT TOWERS FOR DIFFER' ~ ~ ~ ~ ~
INDUSTRIAL AND ENGINEERING CHEMISTRY
October, 1934
1071
TABLE111. EXPERIMENTAL DATA RUN NO.
ENTRIINMENT
Lb./sq ft./hr. A
LINEAR VELOCITY Ft./sec.
ABB. TOWER PHESBURE Lb./sq. in.
OF
TOWER TEMP. F.
VAPOR
VAPOR,
DENSITS
W
Lb./cu. It.
Lb./sq. ft./hr.
STD. 2-INCE WROUGHT-IRON P I P E LABORATORY COLUMN; KEROSENE-GAS S Y S T E X ; TRAY SPACINQ, 16 INCHEB;
9G 11G 12G 13G 14G 15G 160 17G 18G 19G 20G 21G 22G 23G 24G 25G 26G 27G 28G L'9G
0.161 0.166 0. I31 0.318 0.114 0.300 0.088 0.373 0.286 0.144 1.150 0.!>51 0.016 3.320 0.394 0.084 0.006 0.887 3 . '400 0. :!60
1.32 1.42 1.66 1.62 1.37 1.97 0.94 1.40 1.16 1.36 2.12 2.14 0.72 2.34 1.95 0.94 0.64 2.09 2.29 1.90
51G 52G 53G 54G 55G 56G 57G 58G BOG 61G 62G 63G 64G 65G 83G 84G 85G 86G 87G 88G 89G 9OG 9lG 92G 94G 95G 96G 97G
0.1025 0.030 0 . 1083 0.050 0.815 1.165 0.241 0. ,324 OA18 0.019 0.862 1.230 1.120 0.123 0.015 2.760 0.010 0.015 3.20 0 . '758 3.69 3.40 0.52 0.008 0,00014 3.0 3.39 1.42
1.60 2.04 1.94 3.57 4.07 4.34 2.76 2.54 2.99 1.14 3.05 2.96 3.04 2.04 1.15 1.55 1.22 1.455 1.48 3.27 4.60 5.98 1.37 1.13 1.145 3.81 5.63 3.01
0.112 0.142 1.010 0.111 0.716 0.708 1.325 2.010 0.414 0.019 0.915 1.490
1.99 2.36 3.48 2.14 3.10 3.98 4.18 5.32 3.00 1.11 3.78 4.29
14.80 14 80 15.15 15.10 14.60 15.10 14.45 14.60 14.70 14.72 15.67 15.67 24.10 16.10 15.35 14.35 14.35 15.60 15.88 15.50 I
B.
D.
69 69 66 66 67 67 67 70 70 70 70 75 75 80 78 74 74 78 67 70 68 68 60 61 70 60 60 60
11s X
0.2015 1.002 0.186 0.0661 0.14 0.658 3.26 0.034 1.07 4.05 2.44
30 FOOT COMXERCIAL ABSORBERB;
IC
2C 3c 4c 5C 6C 7c 8C 9c
0.72 0.89 0.96 1.22 1.35 1.51 1.73 1.84 2.38
1.09 1.54 0.907 0.727 0.93 1.31 2.2 0.55 1.52 1.92 1.88
0.0491 0.0498 0.0515 0.0514 0.0487 0.0515 0.0475 0.0472 0.0486 0.0497 0.0555 0.0533 0.078 0,0587 0.0528 0.0463 0.0471 0.0553 0.0573 0.0542
CONSTANT, Ca
CAREY'S CONSTANT,
Kb
ENTRAINED LIQUID CAUGHT I N QLASS W O O L
232 255 308 300 240 357 161 238 203 244 424 412 203 495 371 157 108.7 417 471 371
148 161 191 185 153 221 104 154 130 154 253 251 102 288 227 102 70.8 254 277 224
0.041 0.045 0,053 0.052 0.043 0,063 0,029 0.043 0.036 0.043 0.070 0.070 0.028 0.080 0.063 0.028 0.020 0.069 0.077 0.095
0.0530 0.0505 0.0593 0.0572 0.0622 0.0644 0,1090 0.1087 0,1080 0.1100 0.1093 0.1080 0.1082 0.1120 0.3570 0.3565 0.3565 0.3570 0.3790 0.1086 0.1086 0.0590 0.3655 0.3670 0.3605 0.1055 0.0578 0.1096
306 370 414 735 911 1005 1085 995 1165 451 1202 1155 1185 825 1480 1990 1563 1870 2020 1275 1800 1270 1800 1495 1488 1450 1170 1190
187 231 239 432 514 557 463 424 498 191 511 493 507 346 348 468 368 440 461 545 768 733 419 347 348 625 683 503
0.052 0.065 0.067 0.120 0.143 0.155 0.128 0.117 0.138 0.053 0.142 0.136 0.128 0.096 0.097 0.130 0.102 0.122 0.128 0.151 0.212 0.204 0.117 0.097 0.097 0.174 0.191 0.140
206 253 381 228 338 444 466 612 327 184 427 486
0.062 0.070 0.106 0.064 0.094 0.120 0.129 0.169 0.091 0.051 0.119 0.132
BAME A S A WITH 2D-INCH TRAY SPACINQ
14.40 .. 14.65 15.37 14.52 15.10 15.85 15.95 16.35 15.00 34.00 15.60 16.10
86 _. 83 83 83 83 82 82 82 79 79 79 79
12'/r-INCH I . D. WROUQHT-IRON FRACTIONATINQ COLUMN; KEROBENE-AIR SSSTEX;
1s 2s 3s 4s 5s 6s 7s 8s 9s 10s f
75 70 75 77 75 74 73 75 73 75 65 75 70 64 64 64 63 63 63 63
SOUDERB AND
BROWN'S
B A M E AB A W I T E ZCINCH TRAY BPACING
16.60 17.60 18.55 17.90 19.10 20.20 34.00 34 34 34 34 34 34 34 114 114 114 114 114 34 34 18.6 114 114 114 34 17.85 34 C.
lO6G 107G 108G 109G 1lOG lllG 112G 113G 114G 115G ll6cl 117'3
E.
M.4ss VELOCITY
14.1 14.1 14.1 14.1 14.1 14.1 14.1 14.1 14.1 14.1 14.1
80 83 83 86 86 85 84 72 74 74 74
0.0417 .. .~~. 0.0449 0.0468 0.0444 0.0467 0.0480 0.0483 0.0514 0.0467 0.1054 0.0498 0.0500
299 381 586 342 52 1 690 727 985 504 422.5 678.0 772.5
TRAY BPACINQ, 15 I N C E D S ;
0.075 0.074 0.074 0.074 0.074 0.074 0.074 0.075 0.075 0.075 0.075
294 412 245 195 250 353 590 148 408 516 506
E N T R A I N E D LIQUID DYED PURPLE
154 212 126 101 129 182 304 77 212 269 263
0.042 0.059 0.036 0.028 0.036 0.050 0.084 0.021 0.058 0.074 0.072
T E N TRAYS, 22-INCH BPACINQ; 6 F E E T FROM TOP TRAY TO TOP O F ABSORBER; TWO MIBT EXTRACTORS LOCATED 4 FEET A B O V E TOP TRAY; GAS OIL-REBIDUE QAS SYSTEM
1.58 1.52 1.60 1.90 1.88 2.25 2.05 2.16 2.44
45 45 45 45 45 45 45 45 45
60 60 60 60 60 60 60 60 60 (Continued on next page)
far greater in the 121/2-inch tower, as a fog of kerosene floated out of the top of the tower during each run, although the distance from the upper tray to the top of the tower amounted to 71/* feet. KOvisible fog appeared in any of the runs on the glass column.
0.16 0.16 0.16 0.16 0.16 0.16 0.16 0.16 0.16
911 877 924 1093 1081 1295 1180 1241 1405
317 305 321 380 375 450 409 431 488
0.088 0.084 0.089 0.105 0.104 0.125 0.114 0.120 0.135
Further data are now being obtained in this laboratory on the 12l/~-inch semi-commercial column with gas oil and water, A circulating pump will be installed so that the liquid can be pumped over the lower tray a t various rates. I n this way actual absorber conditions will be more nearly duplicated.
I N D 'I;S T R I A I, A i Y D E N G I N E E R I N G C H E 1cI I S T R Y
1072
1-01. 26, No. 10
TABLEI11 (Continued) VELOCITY
RUN No.
ENTRAINMENT
Lb./sq. ff./hr.
LINEAR VELOCITY Fl./sec.
.kBS.
TOWER PRESSURE Lb./sq. in.
TRAY SPACING Inches
Ton ER TEMP. ' F.
VAPOR DENSITY Lb./cu. f t .
OF VAPOR,
W
AND
BHOWN'S CONSTANT.
CAREY'S CONSTANT,
Ca
Kb
428 428 428 428 368 368 368 368 368
225 225 225 225 192 192 192 192 192
0.063 0.063 0.063 0.063 0.053 0.053 0.053 0.053 0.053
230 230 230 230 230 230
154 154 154 154 154 154
0.042 0.042 0.042 0.042 0.042 0.042
L b . / s q . .ft./hr.
F. LABORATORY G L A S U COLUMN: B E R O S E N E - h 1 R SYSTEM
1A 2A 3A 4A 5A 6A ?A SA
0.038 0.042 0.077 0.302 0.58 0.18 0.037 0.034 0.031
1.68 1.68 1.68 1.68 1.40 1.40 1.40 1.40 1.40
10A 11A 12'4 13A 14A 15.4
0.112 0.06 0.04 0.025 0.018 0.01
1.45 1.45 1.45 1.45 1.45 1,45
SA
22 20 18 16 12 14 18 20 22
-
80 80 80 80 68 68 68 68 68
0.071 0.071 0 071 0.071 0.073 0.073 0.073 0.073 0.073
SAME A S F FOR KEROSENE-NATURAL GAS SYSTEM
G.
a
14.1 14.1 14.1 14.1 14.1 14.1 14.1 14.1 14.1
12 14 16 18 20 22
14.1 14.1 14.1 14.1 14.1 14.1
68 68 68 68 68 68
0,044 0.044 0.044 0.044 0,044 0.044
W
[&(dl
s K P -
- ddI"2
ACKXOWLEDGMENT
L; (didz)')'
TABLE IV.
GLASS-COLUXN DATA(FIGURE 9)
(Kerosene-air system; plate spacing, 14 inches)
R U N No. 16.4 17A 18A 19A 20A
LINEAR ENTRAINMENT VELOCITY SUBMERGENCI DROP Lb./sq. ft./hr. Ft./sec. Inches Inches of H 2 0 0.017 0.030 0.044 0.046 0.059
1.3 1.3 1.3 1.3 1.3
1.0 1.5 2.0 2.5 3.0
HEIGHT OF FROTH
21A 22A 23A 24A 25A 26A 27A 28.4 29A 30A 31A 32A 33A 34A 35A 36A 37A 38A 39A
0.40 0.52 0.84 1.20 1.70 1.80 2.00 2.02 2.22 0.90 1.10 1.20 1.42 1.48 1.62 1.80 2.00 2.10 2.48
Inches 4.00 4.50 5.00 5.10 5.50 6.00 6.50 4:50 5.00 5.05 5.30 5.50 5.55 5.55 5.85 6.00 6.50
1.3
...
1.9
...
2.6
EFFECTIVE LENGTH OF
SLOTS
Inches 0.20 0.30 0.40 0.50 0.51 0.60 0.60 0:io 0.30 0.31 0.40 0.50 0.50 0.60 0.62 0:74 (1.81
If the designers of absorption towers would provide curved tubing connections a t several points in the tower immediately below different trays, much reliable commercial data could be obtained. The space in the top of an absorber might also be equipped with several such sampling devices a t different distances above the top tray for the purpose of studying the effect of spacing.
The writers wish to express their appreciation for the assistance given by several of the students in petroleum engineering a t the University of Oklahoma-C. W. Cannon, E'. B. Emerson, C. A. Jackson, J. G. Stephen, and R. W. Whitson-in . . the construction and operation of the expericolumns. The Phillips Petroleum Company cooperated by furnishing commercial data from one of their natural gasoline plants in the Oklahoma City field. The Patent Chemicals Company of Newark, S. J., donated a sample of oil-soluble Petrol Purple (I-hydroxy-4-p-toluidoanthraquinone) which was used for coloring the kerosene. The Tulsa Boiler & Machinery Company designed and h i l t the 12'/?-inch i. d. semi-commercial column.
(1) Carey, Chemical
LITERATL-RE CITED Engineers Handbook, p. 1197, McGraw-Hill
Book Co., New York, 1934. (2) Chillas and Weir, IND.EKQ.CHEK, 22, 206 (1930). (3) Holbrook and Baker, Ibid., 26, 1063 (1934). (4) Kallam, F. L., Petroleum Engr., 5, 33 (April, 1934). (5) Ibid., 5, 29 (June, 1934). (6) Souders and Brown, IXD.ENG.CHEM.,26,98 (1934). (7) Walker, Lewis, and McAdams, "Principles of Chemical Engineering," 2nd ed., p. 400, McGraw-Hill Book Co., New York, 1927.
RECEIVEDMay 7, 1934.
Presented before the Division of Petroleum Chemiatry a t the Twelfth Midwest Regional Meeting of the American Chemical Society, Kansas City, Mo., May 3 to 5, 1934.
CONCLUSIONS
A study of the figures showing the relationship between entrainment and linear velocity shows that there are tn-o causes for entrainment: (1) At lower velocities and greater plate spacings, entrainment is the result of the floating of minute liquid droplets from one tray to another. (2) At higher velocities and lesser plate spacings, entrainment is due mostly to the splashing of large drops of liquid as the result of the jetting action of the vapor. (3) The rate of increase of entrainment is slow up t o a certain point, after which the increase is very ra id. This critical point is no doubt the velocity above which t t e jetting action begins to control. (4) The various factors which affect the values of C in Souders and Brown's equation and K in Carey's equation, such as tower design and the physical properties of the liquid and gas, will require further investigation before any general relationship can be developed.
SUSQUEHANN.4 C O L L I E R Y , NANTICOKE
