FEQQMEVEG VELGQTFES
N fiflgfiii 33%“?! CG’LEMNS

”that: 50? Ha 909m of M.S.
MiCHWAN S‘FAY‘E GfiLLBGI
C3239?“ Gaeiéfea $3M:
Efi-é

This is to certifg that the

thesis entitled
FLOODINC VELOCITIES IN BUBBLE PLATE COLUMNS
presented by
Charles Carleton Sisler

has been accepted towards fulfillment
of the requirements for

Master's degree in Chemical Engineering

Major professé

Date May 27; 19514

 

FLOODING VELOCITIES IN BUBBLE PLATE COLUMNS

BY

Charles Carleton Sisler

A THESIS
Submitted to the School of Graduate Studies of Michigan
State College of Agriculture and Applied Science
in partial fulfillment of the requirements
for the degree of

MASTER OF SCIENCE

Department of Chemical Engineering

1954

ACKNOWLEDGEMENT

The author is indebted to Dr. Carl M. COOper
for his invaluable guidance, to Mr. William Clippinger
and Mr. Kenneth L. Turbin for their assistance in the
installation and modification of the experimental equip-
ment, and to Mr. R. F. Romell, of the Vulcan Copper and
Supply Company, and Mr. R. C. Jente, of the Monsanto
Chemical Company, for their help in the compilation of

the bibliography.

33 1.303

{on

1“;

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TABLE 9;: CONTENTS

INTRODUCTION
SURVEY OF PREVIOUS STUDIES
Allowable Vapor Velocity
Pressure Drop
Entrainment
Weir and Downspout Design
Plate Stability
Flooding Velocity
EXPERIMENTAL EQUIPMENT
PROCEDURE AND CALCULATIONS
DISCUSSION OF RESULTS
SUMMARY
RECOMMENDATIONS FOR FUTURE WORK
BIBLIOGRAPHY

APPENDIX

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to

m
HHHH o
mrmomm m H

17
23
31
31+
35

37
1+2

Figure

Figure

Figure

Figure 4

Table

Table

Table

Table

Table

Table

Table

I.

III.

IV.

VI.

VII.

INDEX 39 FIGURES AND TABLES

 

Schematic Diagram of
Equipment and Piping

Photograph of Equipment
Pressure Drop Kg, F

Steam Flow Rate
XE- Controller Setting

Summary of Data and
Calculations, AtmOSpheric Runs

Summary of Data and
Calculations, Pressure Runs

Summary of Data and
Calculations, Vacuum Runs

Consolidated Data for
AtmOSpheric Runs

Consolidated Data for
Pressure Runs

Consolidated Data for
Vacuum Runs

Pressure Gauge Calibration

1+3

44

45

47

48

1+9
51

 

INTRODUCTION

The capacity of a bubble plate column is usually
limited by the quantity of vapor that can rise through the
column without causing some undesirable effect. In many
cases the maximum allowable vapor velocity is the velocity
above which the liquid will no longer flow down from plate
to plate in a normal manner, and the column is said to
flood. In other cases the specifications for the overhead
product from the column may necessitate complete freedom
of contaminants that are present in the liquid, and the
allowable Vapor velocity is one that will result in no
appreciable entrainment of liquid in the vapor. Other un-
desirable effects that sometime arise from excessive vapor
velocities are channeling of vapor through only a portion
of the bubble caps on a plate and dumping of liquid through
inactive caps.

Economic considerations dictate that a column
should be designed with as small a diameter as is consis-
tent with satisfactory operation at the design capacity.
Also, a column that is grossly oversized in diameter may
have unstable plates, and the dumping of liquid through
inactive caps may result in a low distillation efficiency.
(27) Yet the only methods available for calculating the
maximum allowable vapor velocity, and hence the diameter
of the column, are empirical, and there is no general
agreement as to which of the methods gives the most reli-

able estimate of allowable velocity.

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All the methods in common use today are related
to the "F-factor", which is defined as:

0.5
F = v (av/61)

where V is the superficial vapor velocity, based on column
cross-section, in feet per second, and dv and d1 are the
vapor and liquid densities, respectively, in pounds per
cubic foot.

One design procedure consists of the assumption
of a vapor rate, calculation of the pressure drop through
the plates, and selection of a plate spacing such that the
liquid backup in the downSpouts will be high enough to
permit liquid downflow against the pressure drop. The F-
factor enters this procedure, because the commonly used
methods calculate that part of the pressure drop which is
due to flow of vapor through the risers and caps as prOpor-
tional to the square of the vapor velocity. Expressed as
head of liquid, this pressure drop is calculated as propor-
tional to Vzdv/dl, which is F2. (12, 15, 17, 20, 29)

Other procedures in common use today are based
upon entrainment considerations. Most of the methods are
intended to permit calculation of a vapor velocity such
that entrainment is negligible, or else a velocity that
is typical of commercial practice. (8, 9, 28, 29, 46, 47,
57) Since increased vapor velocity, up to a certain point,

results in increased plate efficiency despite the increased

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entrainment, one equation has been prOposed as a means of
estimating the vapor velocity at which distillation effi-
ciency will be at a maximum. (19) None of these methods

is purported to permit calculation of the vapor velocity

at which the column will flood.

The methods based on entrainment agree in that
the calculated vapor velocity is proportional to the minus
one-half power of the vapor density, hence F would be con-
stant. In some methods other variables, such as liquid
density, interfacial tension, plate spacing, and bubble
cap slot area are also introduced.

The objective of this study was to determine the
flooding velocity of a pilot-plant sized distillation col-
umn at different vapor densities to ascertain whether the
flooding took place at a fixed value of F.

Using steam and water in the experimental column,
the flooding velocity was determined at three different
pressure conditions: atmospheric, 40 psia., and at about 3
or 4 psia. The F-factor at which flooding took place de-
creased with decreasing vapor density. The pressure drOps
observed were not proportional to F2, except at constant
vapor density. At constant F the pressure drop increased
with decreasing vapor density. These observations suggest
a need for improvement of methods for predicting pressure
drop through bubble plates.

As the factors that contribute to the flooding

-4-

of bubble plate columns are numerous and interacting, a

brief survey of pertinent literature follows.

_5-.

SURVEY 9;: PREVIOUS STUDIES

Allowable Vapor Velocity

 

Although the present methods for the calcula-
tion of allowable vapor velocity leave much to be desired,
they are a substantial improvement over the rules-of-thumb
developed in the early days of continuous fractionation in
bubble plate columns. In 1922 Peters (38) recommended a
maximum superficial velocity of l to 1.3 feet per second.
In 1929 Chillas and Weir (ll) advocated the use of higher
velocities, and suggested that baffles be installed to de-
crease entrainment. Commenting on their paper, Peters
said, "We found that really the limit is not the velocity
at all . . . It's the pressure drop in almost every case."
Badger and McCabe (2) state that the vapor velocity, in I
feet per second, ordinarily should be equal to the distance
between plates, in feet.

Souders and Brown (46, 47) stated that the vapor
capacity of a column was usually limited by the quantity
of entrainment that could be tolerated. They proposed a
theoretical equation containing an empirically derived
constant for calculation of the maximum allowable vapor
velocity:

0.5
W = C [dv(d1'dv) ]
where W is the mass velocity of the vapor, in pounds per
hour per square foot, C is a constant, and dv and (11 are

vapor and liquid densities, respectively, in pounds per

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-6-

cubic foot. Theoretically, with proper evaluation of the
constant, this is the equation for the mass velocity of
vapor that would Just suspend a spherical drop of liquid
against the force of gravity, less bouyancy. They eval-
uated the constant from operating data for a number of
commercial columns, and published a graph showing the value
of C for various plate spacings. Two curves were presented
for two different surface tensions. Later Brown (8) mod-
ified the graph by adding more curves for various surface
tensions.

Carey (9) published a similar equation,

0.5
v = K [(dl-dv)/dv ]

which is the same as the Souders and Brown equation except
that both sides have been divided by the vapor density, to
give an expression for allowable linear velocity rather
than mass velocity. Tabulated values of the constant K
were given for various plate spacings and liquid seals.
Carey mentioned some of the complexities other than entrain-
ment that result from high vapor velocities, such as change
in the type of vapor-liquid contact, froth buildup, Jetting
or spouting, and change in weir and downspout performance.
Edmister (18),presented a graph based on the
work of Souders and Brown (47) and Peavy and Baker (36)
for estimation of allowable vapor velocity as a function

of vapor density, liquid density, liquid seal, and the

plate spacing less the depth of liquid on the plate. He

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recommended it for preliminary design only. Clay, Hutson,
and Kleiss (13) compared a capacity curve calculated by
the Edmister method with their curve for 90 percent of
experimental flooding load. The average agreement was
better for the Edmister method than for the Souders and
Brown method, but the Edmister curve was the wrong shape,
giving an estimated capacity that was too low at high
pressures and too high at low pressures.

Kirkbride (29) recommended that the diameter of
a column be calculated so that entrainment is nil, and that
plate Spacing be calculated afterward so that the liquid
head in the downspout is adequate. He based the diameter
on a maximum allowable vapor velocity calculated by the
equation:

0.5
v = 5.5 (T/MP)

where V is the allowable velocity in feet per second, T is
the vapor temperature in degrees Rankine, M is the molecular
weight of the vapor, and P is the absolute pressure in
pounds per square inch. It is to be noted that the term
T/MP is proportional to the reciprocal of the vapor density
if the vapor is treated as an ideal gas. Kirkbride says
this equation is conservative, and that the calculated veloc-
ity can be exceeded by 100 percent without entrainment be—
coming important, provided the plate spacing is adequate to
handle the liquid load.

EdulJee derived an expression for estimation of

E‘s

 

-8-

the vapor velocity at which distillation efficiency is
maximum, in contrast to the velocities calculated by the
above methods, at which entrainment is minimum. His equa-
tion is:
dv v2 = 0.375

As entrainment is appreciable at the velocity calculated
by this method, the method cannot be used in cases where
entrainment would affect some quality of the product such
as taste, odor, or color.

Some designers estimate the maximum allowable
vapor velocity in terms of a modification of the factor F
and define the factor as V(dv)0'5, with no mention of the
liquid density. (28) Since the range of liquid densities
normally encountered in distillation columns is quite narrow
compared to the range of vapor densities, a design procedure
that consistently neglects the liquid density (tantamount
to considering it to be constant) would not differ a great
deal from a procedure that takes liquid density into consid-
eration.

Zenz (57) advocates calculation of the vapor
capacity per bubble cap rather than the superficial veloc-

ity based on column cross-section. He offers the equation:

1.5 0.5
VC :2 SO Mal/av)

2.43

 

where V0 is vapor capacity in CFM per cap, S0 is the slot

opening in inches, W is the total slot width per cap, and

-9...

d and (1V are the liquid and vapor densities, respectively,

1
in pounds per cubic foot. In order to use this equation a
designer must assume a slot opening. Zenz mentions that
slots should be blown open no less than 0.3 inches and no
greater than 1.25 inches. It seems that a designer would
require specific experience upon which to base a choice of
slot openings, as the above limits represent an eightfold
variation in cap vapor capacity.
Pressure 2322.

Pressure drop is important in a study of column
flooding since it affects the height of liquid backup in
the downspouts, and hence affects the flooding velocity at
any given plate Spacing.

Cicalese, 55 gl,, (12) present equations for
calculating the pressure drop for vapor flow through the
cap riser, reversal of flow, flow through the dry slots,
and flow through the liquid on the plate. Dauphine (15),
Edmister (l7), and Eld (20) also give methods for calcu-
lating the pressure drop. All these methods indicate that
the items contributing to pressure drop can be grouped into
two categories, one of which is proportional to F2, the other
of which is a function of the slot submergence and the
effective density of the fluid.

Rogers and Thiele (42) discuss the effect of the
relative height of the weir and the cap slots and the effect

of foam height on pressure drop.

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Souders, Huntington, Corneil and Emert (48) con-
cluded that the pressure drop is influenced greatly by the
head of fluid (usually a mixture of liquid and vapor) re-
quired to pass the liquid into the downspout. I
Entrainment

Entrainment can be classified into several basic
types: small drOplets entrained from the liquid surface at
moderate vapor velocities, large dr0ps splashed by a Jetting
action at higher velocities, and froth resulting from.the
foaming characteristics of the material. (1, 30, 33) Strang
(50) also reported considerable re-entrainment of drops that
had collected on the bottom of the plate and flowed to the
edge of the vapor risers.

Small droplets have no effect on flooding, and
little effect on column operation except in those cases
where some quality of the product, such as taste, odor, or
color, is concerned. Large drops have an appreciable effect
on plate efficiency, and can contribute slightly to a ten-
dency to flood by increasing the amount of liquid downflow.
Large quantities of froth-can cause flooding either by
interfering with the flow in the down8pouts or by filling
the space between plates, since the hydraulic gradient to
cause flow across the plate is much higher for froth than
for liquid. If appreciable froth is entrained in the vapor
flow to the next plate, a decrease in plate efficiency and

a slight increase in the liquid load result. (13, 42, 48)

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The type and quantity of entrainment depend upon
many factors. Much has been written about the effects of
superficial velocity, slot velocity, vapor density, and
plate spacing. (1, 10, 25, 55, 43, 45, 50, 53, 54)

The effects of foaming tendency and interfacial
tension are discussed by Kirschbaum (30, 33), White (56),
and Souders and Brown (47). These effects sometimes vary
in an unpredictable manner. Pyott, Jackson, and Huntington
(39), working with air and kerosene, got different curves
of entrainment 13, either mass velocity or linear velocity,
for different temperatures. They explained this difference
as due to a change in foaming characteristics. Rhodes and
Slachman (41), distilling a benzene—toluene mixture, ob-
served that entrainment went through a minimum at 60-70
mole percent benzene, without apparent change in foam or
manner of boiling. The variation seemed to be in drop size.
Distilling an ethanol-water mixture, they observed that
foaming varied with composition. They noted entrainment
due to foam rising to the next plate at ethanol concentra-
tions higher than 30 percent. Thompson (52), working with
the system ethanol-water-calcium chloride, reported that the
critical vapor velocity, beyond which entrainment increased
rapidly, was lower for higher ethanol concentrations.
Stabnikov (49) blew air through water, solutions of sodium
hydroxide, and solutions of sodium hydroxide with soap, and

found that for superficial velocities below 0.25 meters per

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-12-

second, entrainment was greater for foaming liquids than
for non-foaming liquids; at higher velocities the converse
was true.

Several equations have been derived for calculat-
ing the effect of entrainment on plate efficiency or the
required number of plates. (3, 4, l4, 19, 40, 43, 47, 53)
Peavy and Baker (36) found the optimum vapor velocity cal-
culated by the method of Colburn (14) to be beyond flooding
velocity in many cases. Brown and Lockhart (7) studied
data from both laboratory and commercial columns, and con-
cluded that plate efficiency levelled off at a maximum,
extending in most cases over a range of vapor velocities
of from 0.8 to 1.2 times those calculated by the method of
Souders and Brown (47).

Weir and Downspout Desigg

A bubble plate column floods if the discharge
weirs and downSpouts fail to carry liquid away from each
plate at a rate adequate to maintain steady-state conditions.
If steady-state conditions at the required liquid rate can
be maintained only with a very high liquid level on the
plates, the column will not necessarily flood, but the
pressure drop may be obJectionably high (12, 48), and en-
trainment may be increased due to the decreased distance
between the liquid surface and the plate above (39).

Methods for estimating the liquid level in the
downspouts are presented by Kirkbride (29) and White (56),

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both of whom itemize and discuss the various items that
constitute this total backup head. As these methods do
not take into consideration the possible interference of
froth with downspout operation, both Kirkbride and White
recommend that the plate spacing be at least twice the
calculated height of liquid in the downspouts.

Kallam (27) pointed out the importance of the
configuration of the discharge weir and downspout on
liquid capacity. He found that a downspout bounded by a
weir on one side and by the column wall on the other side
had a higher capacity than a downspout with the same cross-
sectional area bounded on all sides by a weir. In the
latter case, liquid falling from one portion of the weir
interfered with that falling from another part. He ob-
tained curves of flooding velocity of an absorber at various
oil-to-gas ratios, with several different downSpout arrange-
ments.

Souders, Huntington, Corneil, and Emert showed
that a downspout can operate under three distinct condi-
tions of fluid head: 1) at low heads, as a weir; 2) at inter-
mediate heads, as a free-running orifice, accepting a mix-
ture of liquid and vapor, but having sufficient vortex to
allow separation; and 3) at high heads, as an orifice run-
ning full, with its capacity diminished by disengagement

within the orifice.

‘44.;

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-14-

Carey (9) mentioned the need for froth dis-
engagement space between the bubble caps and the discharge
weir. Peavy and Baker (36) suggested placing a top baffle
in front of the weir so that the liquid must flow under it,
as an aid to disengagement.

White (56) recommends that downspouts be delib-
erately over-designed, as they constitute a relatively un-
important cost item but are an important factor in flooding.
Plate Stabiligy

A bubble plate is said to be stable if vapor
issues from all the slots on the plate. A plate that is
unstable, due to poor design, is characterized by a high
hydraulic gradient, with the liquid at the liquid inlet end
of the plate so deep that vapor preferentially flows through
the shallower part of the plate. Liquid may dump through
the risers of the inactive caps. As the vapor passes
through a fewer number of caps than the designer intended,
it flows at a higher velocity, resulting in increased en-
trainment. The higher velocity also causes a greater pres-
sure drOp, which further aggravates the unstable condition
by increasing the liquid level in the downspouts and on the
deep side of the plate. (28)

Plate instability can cause a column to flood,
especially if it is a large column with a high liquid rate,
when the excessive hydraulic gradient causes liquid to

back up to the top of the downspout. Harrington, Bragg,

l1

\—

-15-

and Rhys (24) describe the difficulties encountered with
several extremely large columns installed by the Standard
Oil Company of New Jersey around the beginning of World
War II. In addition to an excessively high liquid gradient
caused by the large quantity of liquid flowing over a con-
ventional arrangement of caps and hold-down bars, some of
these columns exhibited a unique problem due to vapor cross
flow. As vapor passed through caps at the liquid discharge
side of the plates only, it had to cross to the opposite
side of the column after it passed each plate. One column
had large I-beams to support the plates, and the clearance
beneath the beams was such that the velocity of the vapor
cross flow was more than ten times the calculated super-
ficial velocity. The cross flow entrained liquid from the
shallow side of the plate and deposited it on the deep side.
The buildup would continue for about two minutes, after
which the differential pressure would become great enough
to blow vapor up through the deep side of the plate, after
which the cycle would repeat. Another column had a similar
difficulty with vapor cross flow, but flooded due to full
downspouts instead of surging.

Several methods for the calculation of hydraulic
gradient and the design of stable plates have been published.
(16, 21, 22, 23, 28, 51)

Eld (20) and Kallam (27) caution against design-

ing columns larger than necessary. At relatively low vapor

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-16-

rates not all the caps will be active, and liquid will
dump through the risers of the inactive caps.

Flooding Velocity

 

Very little has been published about the experi-
mental determination of flooding velocity.

Since thissxudy was completed, Clay, Hutson, and
Kleiss (13) have reported an investigation of the effect
of load and pressure on performance of a commercial bubble
plate column separating isobutane from normal butane.
Flooding in their column was due to the rising of the froth
level to the next plate. The downspouts worked satisfac-
torily, and the downflow rate had no appreciable effect on
the flooding velocity. They recommend the use of the
Souders and Brown method in lieu of better capacity data,
and suggest multiplication of the constant by 1.33 for
light hydrocarbons. This will give a curve equivalent to
about 90 percent of the experimentally-determined flooding
velocity.

Peavy and Baker (36) were unable to determine
accurately at what velocity flooding began in laboratory
investigations, as the flooding velocity varied with the
rate of increase in vapor velocity. Accordingly, they
recommend that columns be operated well below the flooding

velocity range.

 

 

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-17-
EXPERIMENTAL EQUIPMENT

A modified Model A—2 Experimental Laboratory
Distillation Unit, manufactured by the Vulcan Copper and
Supply Company, of Cincinnati, Ohio, was used for this
study. The column of this unit is made from 8-inch seam-
less copper pipe, and contains 24 bubble plates spaced on
6-inch centers. Each plate has two 3-inch Vulcan pressed
bubble cap assemblies.

Total slot area is 5.54 square inches. The cross-
sectional area of the downpipes is 3.3 square inches, and
the effective length of both the distributing weir and the
overflow weir is about 6.5 inches. The effective cross-
sectional area of the column, allowing for the downpipe,
is about 0.323 square feet.

Certain modifications of auxiliary equipment were
required for this study. The experimental objective was
the determination at three different pressures of the vapor
velocity that would cause the column to flood, as evidenced
by the differential pressure across the column. A steam
and water system was used to avoid the complications of
composition changes.

Accordingly, the calandria was blanked off and
steam was introduced directly into the bottom of the column.
The perforated Sparger was removed. Water from the bottom

of the column was pumped through a rotameter to the top

-18-

plate of the column to provide a metered liquid downflow.
Figure l is a schematic diagram of the equipment and
piping.

The valving arrangement was necessarily dif-
ferent for operation under the three pressure conditions:
atmospheric, pressure, and vacuum. For the atmospheric
runs the atmospheric vent valve V-6 (referring to Figure
l) and needle valve V-5 were open to keep the condenser
at atmospheric pressure. Valve V-2 was open so that con-
densate from the condenser would flow to a barrel on a
scale, to be weighed. Valve V-4 was open, so that any
water accumulating in the bottom of the column, due to
heat losses, would be bled off to another barrel on a scale.
'The liquid level controller in the bottom of the column and
control valve V-9 controlled this flow. All other valves
were closed, except V-lO, by which the downflow rate was
controlled manually.

For the runs under pressure, valve V-7, connect-
ing with a compressed air supply, was open. Condensate from
the condenser was routed through valve V-3 and relief valve
RV-l. A pressure of 25 psig., as indicated by pressure
gauge PG-l at the bottom of the column, was maintained by
careful adjustment of needle valve V-5 and relief valve RV-l.
The relief valve handled a mixture of air and water. Bottom
accumulation was again discharged through valves V-4 and V-9.

All other valves were closed except V-lO, by which the

I1,

I\

..c.

-19-

downflow rate was controlled manually.

For the vacuum runs, valve V-8, connecting with
a vacuum pump, and atmospheric vent valve V-6 were Open.
Needle valve V-5 was Just cracked, to permit a small amount
of air to be drawn into the piping to result in a stable
pressure at the vacuum pump. Condensate from the condenser
was brought through valve V-l to combine with water from
the bottom of the column on the suction side of the pump.
All the condensate was discharged through valves V-4 and
V-9. All other valves were closed except V-lO, by which
the downflow rate was controlled manually.

A larger condenser was installed in place of the
one that came with the equipment. As the unit installed
was a two-pass baffled heat exchanger, not designed as a
condenser, it was connected so as to condense inside the
tubes, and cooling water was piped to the shell. It was
installed in a horizontal position, with the vapor line
from the top of the column connected to the upper half of
the tube bundle. A portion of the vapor line was raised
to prevent condensate from running back into the column.

The separator, where non-condensibles disengaged
from the condensate, consisted of a vertical section of
3-inch pipe, fed at a 3-inch tee in the middle.

A length of Saran tubing was installed vertically,
as shown in Figure 1, connecting the top of the separator

with the water piping below the bottom of the column. This

-20....

tubing and the gauge glass in the bottom of the column
served as the two legs of a manometer to indicate the pres-
sure drop through the column in inches of water. This
arrangement gave greater sensitivity than did the mercury
manometer originally provided with the distillation equip-
ment. Also, trouble with the mercury manometer was ex-
perienced in early exploratory runs, as vapor condensed

in the connecting tubing unless the air purge rates were
increased to a point that they resulted in an appreciable
pressure drop in the tubing. I

Steam was supplied by the College power plant
at a nominal pressure of 100 psig. Unfortunately, the
piping between the power plant and the Chemical Engineer-
ing Building, where the experimental equipment was located,
was so small that the pressure drOpped considerably at the
flow rates used in this study.

A Foxboro Model 40 recording flow controller was
installed to control the steam input to the column. The
flow was measured by the differential pressure across a
1.48l-inch diameter orifice installed in a 3-inch schedule
40 pipe. The pressure in the orifice run was regulated by
a Fisher Model 92-A pilot-operated reducing valve.

The condensate streams from the condenser and
the bottom of the column were collected in open steel barrels
on platform scales.

Figure 2 is a photograph of the equipment.

-21-

*—-N—- Atmospheri c Vent
V-6

 

 

 

 

 

 

 

   

 

 

 

 

a .
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-—-N-—i Compressed Air
V-7
Xv-5
—9%—-—t To Vacuum Pump
a V"
N
g 1/2 QPo-e
Condenser
T-2 ' Q Separator
u I L
z 7
a 2. °
7 k
E a RV-l
E’ '3
E o
5 -———— 3 v-5 V
' 1' 7 3/4 "
:5 '5: — > To Scale.
(H
-1 X - Tank For
:5 .3 V V 2 Overhead
= a 3 a Condensate
gm :3 N
k 1 a: h Rotameter
Tfl A '
fl 90-1 V-lO
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Steam 2— l- I " :
GG _ 11]}ij
RV-2 To Scale
- -4 Tank For
1” v 9 v Battom
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Pump

Figure 1. Schematic Diagram of Equipment and Piping.

-22..

 

Photograph of Equipment

Figure 2.

-23-
PROCEDURE AND CALCULATIONS

Preliminary runs indicated the need for increas-
ing the steam rate in small increments, as the column would
flood after a large increase, even at relatively low steam
rates.

Preliminary runs also indicated that the column
could not be flooded at a pressure much higher than 25 psig.
due to the pressure drop in the steam line from the power
plant. The series of pressure runs, originally planned for
60 or 70 psig., was accordingly run at only 25 psig.

Data were entered in the operating log at fre-
quent intervals. The timing varied, but generally entries
were made at l, 3, 5, 10, 15, 20, 25 and 30 minutes after
the steam control point was changed. Some runs were ob-
served for longer periods if erratic behavior Justified
doing so. Some of the runs, in which the column flooded,
lasted only a minute or two.

The following data were recorded at these fre-
quent intervals: time since controller setting, weight of
overhead condensate collection drum, weight of bottoms con-
densate collection drum, height of water in both sides of
the manometer (the Saran tubing and the gauge glass on the
column), temperatures at bottom and top of column, downflow
rotameter reading, pressure reading at the base of the

column and at the separator. Once during each run the

1‘

(a

-24-

following data were also noted: time run started, steam
controller setting, pressure of main steam line and of
steam at orifice. Thermometers were read to the nearest
half degree 0., pressure gauges to the nearest pound, and
manometer legs to the nearest tenth of an inch.

The data that were obtainable at the main floor
level were usually all obtained within a period of one
minute. The temperature at the top of the column and the
pressure at the separator were read less frequently, and
usually about a minute before the other items.

The bottoms condensate collection drum was on a
dial-type scale, which was read at exact time intervals,
usually of 5 or 10 minutes, timed by a stop watch. The
collection drum for overhead condensate (in the atmospheric
and pressure runs only) was on a beam-type scale. The flow
rate to this drum was determined by timing the interval
between the rising of the beam at two settings, usually
10 pounds apart. Several time and weight readings were
always taken and the increments were checked for uniformity.
This precluded gross errors in scale or watch readings, and
also ascertained that steady state conditions had been
reached before the weight data were taken.

As the original log contained over a hundred
pages, it is not reproduced here in detail; Tables IV, V,
and VI, in the Appendix, are a consolidation of the log,

with the data used in the calculations on one line for each

a . i
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-25-

steam setting. In transferring the data from the log to
the consolidated tables, the condensate collection rate

for each drum was converted to pounds per hour by straight-
forward arithmetic that requires no explanation. A pres-
sure drop figure that was typical for the period during
which the rates were determined was selected for each run.
In the few cases where the pressure dr0p surged more than
one or two inches of water, two figures were entered in

the table, representing the extremes.

Tables I, II, and III in the Appendix develop
the F-factor for each run, for conditions at the bottom of
the column. The bottom of the column was chosen because
both the vapor rate and the liquid downflow rate are highest
at the bottom, due to heat losses. Hence, in this study,
flooding conditions were probably first reached at the
bottom plates.

The runs have been designated by two letters and
a number. The first letters (A, P, or V) signify atmos-
pheric, pressure, or vacuum. The second letters (L or H)
signify a low or high liquid downflow rate. The numbers
indicate sequence.

In all the runs at the "low" downflow rate, the
downflow reading of the rotameter was 12 (arbitrary units).
At the high downflow rate, the rotameter read 24. These
rates were determined to be 304 and 671 pounds per hour,

respectively. For the atmospheric and pressure runs, wherein

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-26-

any condensate that accumulated at the bottom was with-
drawn and weighed separately, this accumulation was added
to the metered downflow rate. For the vacuum runs no such
correction was possible.

The steam input, in pounds per hour, is the
total condensate rate, since at steady state conditions,
the steam input and the condensate discharge must be equal.
A graph comparing condensate rates with the steam control-
ler setting, included in the Appendix, shows some scatter.
The controller setting and this graph were used to estimate
the steam input rate in those cases where the column flooded
rapidly and no condensate rates were obtained.

The quality of the steam supply was not deter-
mined experimentally. A drain leg and trap were located
just ahead of the regulating valve for the orifice run.

As steam normally leaves the power plant with not more than
5 degrees of superheat (according to power plant personnel)
and passes through several hundred feet of pipe between
buildings, it seems safe to assume that the stream was
saturated just before it was throttled by the regulator,

at whatever pressure existed at that point during any given
run. The steam was also assumed to be dry, although it is
quite possible that some water was entrained at high rates.

If the steam was saturated at line pressure be-
fore throttling by the regulator and the automatic control

valve, it was superheated when it entered the column. It

-26-

any condensate that accumulated at the bottom was with-
drawn and weighed separately, this accumulation was added
to the metered downflow rate. For the vacuum runs no such
correction was possible.

The steam input, in pounds per hour, is the
total condensate rate, since at steady state conditions,
the steam input and the condensate discharge must be equal.
A graph comparing condensate rates with the steam control-
ler setting, included in the Appendix, shows some scatter.
The controller setting and this graph were used to estimate
the steam input rate in those cases where the column flooded
rapidly and no condensate rates were obtained.

The quality of the steam supply was not deter-
mined experimentally. A drain leg and trap were located
just ahead of the regulating valve for the orifice run.

As steam normally leaves the power plant with not more than
5 degrees of superheat (according to power plant personnel)
and passes through several hundred feet of pipe between
buildings, it seems safe to assume that the stream was
saturated just before it was throttled by the regulator,

at whatever pressure existed at that point during any given
run. The steam was also assumed to be dry, although it is
quite possible that some water was entrained at high rates.

If the steam was saturated at line pressure be-
fore throttling by the regulator and the automatic control

valve, it was superheated when it entered the column. It

I‘.

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-27-

would accordingly vaporize a slight amount of water from
either the bottom of the column or the bottom plate, and
become saturated at the conditions prevailing there. Thus
for every pound of steam input, slightly over a pound
would rise through the lower part of the column.

Run A-L-l is cited as an example of a typical

calculation:

Steam line pressure gauge reading: 101 psig.
Corrected pressure, from gauge calibration
in Appendix: 92 psig.
Absolute pressure: 92 + 15 a 107 psia.
Bottom temperature, to nearest half degree C: 102.0

Bottom temperature, to nearest degree F: 216

As throttling is isenthalpic, it was possible to
calculate the quantity of saturated steam rising in the
bottom part of the column from enthalpy data, taken from

steam tables (Keenan, J. H., and Keyes, F. G., Thermogy-

 

namic Properties 2£_Steam, John Wiley and Sons, New York,

1936).
hg at 107 psia. = 1,188.4 Btu./lb.

In its final condition, the steam was saturated

at the bottom temperature of 216 degrees F.

hg at 216°F. = 1,151.9 Btu/lb.

.
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Ix

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-28-

The decrease in enthalpy of the steam, 36.5
o
Btu/1b., was used to vaporize water at 216 F. to satur-

ated steam at 216°F. This heat of vaporization is

hfg at 216°F. 1 967.8 Btu/1b.

For every pound of steam input, the amount of

water vaporized in the bottom of the column is
36.5/967.8 1 0.038 lb.
and the steam rising in the column is
l + 0.038 = 1.058 lb.
The steam rate rising in the column is then
(1.038)(251) 1 261 lbs./hr.

The specific volume of the saturated steam is

also taken from the steam tables:
vg at 216°F. = 24.90 cu. ft./lb.

The superficial velocity, based on a cross--

sectional area of 0.323 sq. ft., is calculated
V's (261)(24.90)/(0.323)(3600) 1 5.59 ft./Sec.

The factor F is calculated

0.5 0-5
F = V(dv/dl) = V(vl/vv)

0.5
1 (5.59)(0.01674/2u.90) 1 0.142

-291

The above calculations were repeated for each
run.

Immediately following is Figure 3, which shows
column pressure drop vs, the factor F for the atmOSpheric,

pressure, and vacuum runs.

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.31.
DISCUSSION 9;: RESULTS

In Figure 3 the abscissas were plotted on a scale
prOportional to F2 rather than F, as the literature indi-
cates that pressure drop should be linear with respect to
F2. (12, 17, 20) The data for runs at any one of the
three pressures exhibit this linearity below the flooding
point, but the data for the three series do not coincide.
At any given value of F the pressure drop for the atmos-
pheric series is slightly higher than for the pressure
series, and the pressure drop for the vacuum series is
considerably higher.

During several of the atmOSpheric and pressure
runs, flooding was evidenced by the loss of the liquid
level in the bottom of the column. Data points for those
runs have been encircled on Figure 3, to denote definite
flooding. Some other runs, especially in the pressure
series, showed erratic pressure drops but gave no visible
indication of flooding.

Apparently the column was flooded during most of
the vacuum runs, although the author was unaware of the
flooded condition at the time. There was no visible in-
dication of improper operation. The pressure drop was
high, but steady and reproducible. The condenser discharge
piping was connected with the bottom of the column during

the vacuum runs, so that overhead condensate and any bottom

I‘

\1/

-32-

accumulation could be pumped out of the system, hence a
normal level was maintained in the gauge glass at the
bottom of the column. A

A closer inspection of the pressure drop data
indicates that the column must have been flooded during
many of the vacuum runs. Differential pressures as high
as 198 inches of water were recorded. Since the total
distance between the top plate and the bottom plate was
only 138 inches, water pumped onto the top plate could
not have come down the column, and-must have gone up the
vapor line and through the condenser. The manometer was
connected so as to give the total pressure drop through
the column, the vapor line, and the condenser, but the
pressure drop through the vapor line and the condenser
would be negligible unless they were partially flooded.

In Figure 3 the pressure drop data for the vac-
uum runs show a hump in the F-factor range of 0.19 to 0.21,
with pressure drops ranging from 100 to 150 inches of water.
During the runs in this range the water level probably rose
in the top section of the column above the top plate, and
into the vapor line. At higher F-factors the data lie
along a straight line, but with considerable scatter.

Under vacuum, the column apparently started to
flood at an F-factor of about 0.19 or 0.20, compared to
0.22 for operation at atmospheric pressure or 0.24 for

operation at 25 psig.

,5

-33—

The maximum pressure drop at which the column
could be operated without flooding appears to be 80 or 90
inches of liquid, or perhaps 100 inches under vacuum con-
ditions.

In the atmospheric and pressure runs, Slightly
higher F-factors were permissible at low liquid rates than
at high liquid rates. In the vacuum runs, the flooding
point was not determined with sufficient accuracy to de-
tect the effect of liquid rate. This relationship should
prevail under any conditions, however, as a higher liquid
rate causes a higher head over the discharge weirs, a
higher friction head in the downspouts, and a higher head
over the distributing weirs.

The effect of vapor density on flooding velocity
in a pilot-plant sized bubble plate column was investigated
by flooding the column at three different pressures, using
a steam and water system.

Design methods in common use today predict that
the column should flood at a constant value of the F-factor,
and also predict that the pressure dr0p through the column
(not flooded) should be a linear function of F2.

Experimentally, the linear relationship between
pressure drop and F2 was observed only at constant vapor
density. At constant values of F, a decrease in vapor den-
sity resulted in an appreciable increase in pressure drop.
A decrease in vapor density accordingly lowered the value

of F at which flooding took place, since comparable pres-

sure drops were obtained at lower values of F.

f‘

-35-
‘ RECOMMENDATIONS FOR FUTURE WORK

The results of this study indicate a need for
an improved method of predicting the pressure drop through
bubble plates. Since the equipment and procedure in this
study were not devised for the purpose of obtaining exact
information on the relationship between pressure drop and
vapor density, future work should begin with a preliminary
investigation designed to confirm or refute the observa-
tions of this study.

This preliminary investigation could utilize the
same bubble plate column, with the addition of certain ac-
cessories. The use of air and water at room temperature
is recommended, rather than steam and water. This change
will reduce the amount of mass transfer in the column,
hence should make the data more reliable.

The pressure dr0p data should be taken across
one plate, or across a section of the column short enough
that the change in absolute pressure is of negligible magni-
tude. The test plate (or section) should be located midway
in the column, so that the air will be saturated and in
approximate thermal equilibrium with the water. It should
be equipped with:

l) A sloping manometer, filled with a light liquid
such as water or Meriam red oil, connected with
short sections of air-purged tubing, to read

differential pressure;

1- 'L' _
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(I

-36-

2) An accurate pressure gauge or a large mer-
cury manometer, to indicate gauge pressure;

3) A thermometer; and

4) A gauge glass to show liquid level on the
plate.

Water could be pumped onto the top plate through
the reflux rotameter. A suitable rotameter, a thermometer,
and a pressure gauge should be installed in the air piping.
Barometer readings should be taken, to permit accurate cal-
culation of the air density in the test section.

If the preliminary pressure drop study confirms
the observations made in this study, further investigation
will be needed to develop an accurate correlation between
pressure drop, vapor rate, vapor density, and liquid den-
sity. This would probably involve an extensive study of
pressure drop through dry bubble caps and through wet caps

with various liquids, submergences, and cap layouts.

ri

r.

.i

10.

ll.

12.

13.

-37-
BIBLIOGRAPHY

Ashraf, F. A., Cubbage, T. L., and Huntington, R. L.,
"Entrainment in Oil Absorbers," Ind. & Eng. Chem., gé,
1068-72 (1934).

Badger, W. L., and McCabe, W. L., Elements ngChemical
Engineering, 2nd Edition, McGraw-Hill Book Company,
New York, 1936.

 

Baker, E. M., "Entrainment in Plate Columns," Ind. &
Eng. Chem., 1, 717-8 (1939).

Baker, E. M., and Lindsay, R. A., "Design Calculations
for Plate Columns," Ind. & Eng. Chem., 35, 418-21 (1943).

Beall, I.N., "Fractionation for Absorption Plants," Ref.
& Nat. Gaso. Mfr., November 1930.

Brown, G. c. "Distillation," Trans. A.I.Ch.E., 3g,
321-63 (19365.

Brown, G. G., and Lockhart, F. J., "The Effect of Vapor
Load on Plate Efficiency in Fractionating Columns,"
Trans. A.I.Ch.E., 22, 63-75 (1943)-

Brown, G. C., g§_§1, Unit Qperations, John Wiley & Sons,
New York, 1950.

 

Carey, J. 8., "Plate Type Distillation Columns," Chem.
& Met. Eng., 5g, 314 ff. (1939).

Carey, J. S., Griswold, J., Lewis, W. K., and McAdams,
W. H., "Plate Efficiencies in Rectification of Binary
Mixtures," Trans. A.I.Ch.E., 0, 504-519 (1934).

Chillas, R. B., and Weir, H. M., "Design of Fractionat-
ing Columns," Ind. & Eng. Chem., 22, 206-13 (1930);
Trans. A.I.Ch.E., gg, 79-106 (19297.

Cicalese, J. J., Davis, J. A., Harrington, P. J.,
Houghland, G. 8., Hutchinson, A. J. L., Walsh, T. J.,
"Study of Alkylation-Plant Isobutane Tower Performance,"
Petroleum Refiner, gé, No. 5, 495-511 (1947).

Clay, H. A., Hutson, T., Jr., and Kleiss, L. B., "Effect
of Load and Pressure on Performance of a Commercial
Bubble Tray Fractionating Column," presented at the
Annual Meeting of the A.I.Ch.E. at St. Louis, December
13‘16: 1953.

\1/

[1‘

F
1
,1
e
7

{a

K

’ O

\

q

\ O

O
i
I
I

\_’/

1‘

I
Q <
’1' o
1
I
1
.
1
1

O
1
. 1/
1
I
N
n
K
n
n
O
I
I
O

f.

o
o
L . .
7 U
. . I
f‘ a

. ‘
1 l .
F

e e
.

I 1 .
i v ‘
o

\_ L.
o L. .
1 g 0
' 1
t. 11 \_ O
F
-1. - .l

14.

15.

16.

17.

18.

19.

20.

21.

22.

23.

24.

25.

26.

-381

Colburn, A. P., "Effect of Entrainment on Plate Effic-
iency in Distillation," Ind. & Eng. Chem., g§, 526-30

(1936)-

Dauphine, T. C., "Pressure Drop through Bubble Caps,"
Sc. D. Thesis in Chemical Engineering (1939), Mass.
Institute of Technology.

Davies, J. A., "Bubble Tray Hydraulics," Ind. & Eng.
Chem., 32, 774-8 (1947).

Edmister, W. C., "Hydrocarbon Absorption and Fraction-
ation Process Design Methods: Part 17. Fluidynamics
of Bubble Plate Columns," Petroleum Engineer, 29, No.
3, 193-200 (December, 1948).

Edmister, W. C., "Hydrocarbon Absorption and Fraction- '
ation Process Design Methods: Part 18. Plate Effic- i
iefic ," Petroleum Engineer, 29, No. 4, C45-53 (January, k
19 9 . 1h,

EdulJee, H. B., "Entrainment and Efficiency in Dis-
tillation Columns," Trans. Inst. Chem. Engrs. (London),
24, 128-32 (1946).

 

Eld, A. C., "Pressure Drop in Fractionating Towers,"
Petroleum Refiner, 21, No. 10, 537-9 (1948).

'Gardner, H. S., "Fluid Flow Characteristics of Bubble-

Cap Plates," Sc. D. Thesis in Chemical Engineering
(1946), Mass. Institute of Technology.

Gardner, H. 8., Pike, R. B., Winsche, W. E., and Urbon,
w. J., 'Fluid Flow Characteristics of Bubble-Cap P1ates,’
A.C.S. Distillation Symposium, Mellon Institute, Pitts-
burgh, Pennsylvania, December 30-31, 1946.

Good, A. J., Hutchinson, M. H., and Rousseau, W. C.,
"Liquid Capacity of Bubble-Cap Plates," Ind. & Eng.

Harrington, P. J., Bragg, B. L., III, and Rhys, C. 0.,
Jr., "No Peace for Fractionators,” Petroleum Refiner,
24, No. 12, 502-506 (1945); Oil & Gas Journal, 44, No.

29; 135 ff. (1945). ‘"‘

Holbrook, G. E., and Baker, E. M., ”A Study of En-
trainment in a Bubble-Cap Distillation Column," Trans.
A.I.Ch.E., 0, 520-45 (1935-4); Ind. & Eng. Chem., 26,

 

Joachim and Beardsley, Annual Report, National Advisory
Committee on Aeronautics, 12) 489 (1927).

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27.

28.

29.

30.

31.

32.

33.

34.

35-

36.

37.

38.

39.

40.

139...

Kallam, F. L, "Notes on 8Absorber Design," Article 1,
Petroleum Engineer, 358 (April, 1934); Article 2,
ibid., 29-32 (June, 1934).

Kemp, H. S., and Pyle,C ., "Hydraulic Gradient Across
Bubble-Cap Plates, Chem. Eng. Progress, _5, 435- -51
19 9 .

Kirkbride, C. G., "Process Design Procedure for Multi-
component Fractionators," Petroleum Refiner, 23, No.

9: 321-36 (1944).

Kirschbaum, E., "Efficiency of Rectification Columns,"
Chemische Fabrik, 6, 431-6 (1933).

 

Kirschbaum, B., "Choice of Steam Velocity in Rectify-
ing Columns,” Chemische Fabrik, 181-5 (1940).

Kirschbaum, E., "Behavior of Rectifying Plates at Sub-
atmospheric Pressures and the Computation of the Dia-
meter of Rectifying Columns," Z. Ver. deut. Ing.,

Verfahrenstech., 1940, No. 3, 69- -77.

 

Kirschbaum, E., Distillation and Rectification, Chem-
ical Publishing Company, New York, 1948.

Nelson, W. L., Petroleum Refinery Engineering, McGraw-
Hill Book Company, New York, 194i.

Parrish, P., Design and Working_ of Ammonia Stills, E.
Benn, Ltd., London, I924.

Peavy, Claude C., and Baker, E. M., "Efficiency and
Capacity of a Bubble-Plate Fractionating Column,’ Ind.
& Eng. Chem., 22, 1056-64 (1937).

Perry, J. H., Chemical Engineers' Handbook, 3rd Edi-
tion, McGraw-Hill Book Company, New York, 1950.

Peters, W. A., Jr., "The Efficiency and CapacitZ of
Fractionating Columns,l Ind. & Eng. Chem., 14_, 7

(1922).

Pyott, W. C. Jackson, C. A., and Huntington, R. L.,
"Factors Affecting Entrainment in Bubble- -Cap Columns,"
Ind. & Eng. Chem., g1, 821- -5 (1935)

Rhodes, F. H., "Effect of Entrainment on Plate Effic-
iency in Rectification," Ind. & Eng. Chem., 26, 1333-5
(193 )s ibid.. 27. 272 (1935).

f.

[-1

/\

\__/,

\_,/

41.

42.

43.

44.

45.

46.

47.

48.

49.

50.

51.

52.

53.

-40-

Rhodes, F. H., and Slachman, P. G., "Plate Efficiency
and Entrainment in Distillation," Ind. & Eng. Chem.,

22, 51-5 (1937).

Rogers, M. C., and Thiele, E. W., "Pressure Drop in
Bubble-Cap Columns," Ind. & Eng. Chem., 26, 524-8

(1954).

Sherwood, T. K., and Jenny, F. J., "Entrainment in
Plate Columns," Ind. & Eng. Chem., g1, 265-72 (1935).

Siegel, C. L., "The Design of Bubble-Cap Columns for
Fractional Distillation, Chem. & Met. Eng., 44, No. 9,

493-7 (1937).

Simkin, D. J., Strand, C. P., and Olney, R. B., "Entrain-
ment from Bubble-Cap Trays," presented at the National
Meeting of the A.I.Ch.E. at Washington, March 10, 1954.

Souders, M., Jr., and Brown, G. C., "Design of Vapor-
Recovery and Rectifying Units for Use in Refineries and
Gasoline Plants,” Oil & Gas Journal, 31, No. 5, 34 ff.

(1932).

Souders, M., Jr., and Brown, G. C., "Design of Frac-
tionating Columns: I. Entrainment and Capacity," Ind.
& Eng. Chem., gé, 98-103 (1934).

Souders, M., Jr., Huntington, R. L., Corneil, H. G.,
and Emert, F. L., "Performance of Bubble-Plate Columns:
Froth Heights and Pressure Differentials," Ind. & Eng.
Chem., 39, 86-91 (1938).

Stabnikov, V. N., "Effect of Foam on Entrainment in Cap-
Plate Columns," Khimicheskoe Mashinostroenie, 8, No. 6,

17-21 (1939).

Strang, L. C., "Entrainment in a Bubble-Cap Fractionat-
ing Column," Trans. Inst. Chem. Engrs. (London), gg,

169-78 (1934)-

Technical Advisory Committee Report FMC-15, "Miscel-
laneous Fractionating Techniques," Petroleum Industry
War Council (presented at American Petroleum Institute
meeting at Chicago, November 12, 1946).

 

Thompson, A. K. G., "Entrainment in a Bubble-Cap Distil-
lation Column," Trans. Inst. Chem. Engrs. (London), 14,

119-28 (1936).

Underwood, A. J. V., "The Theory and Practice of Testing
stills,” Trans. Inst. Chem. Engrs. (London), g9, 112-58
1932 .

 

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54.

55.

56.

57.

-41-

Volante, M. A., S. B. Thesis in Chemical Engineering
(1929), Mass. Institute of Technology.

Walker, W. H., Lewis, W. K., McAdams, W. H., and
Gilliland, E. R., Principles 9£_Chemical Engineering,
3rd Edition, McGraw-Hill Book Company, New York, 1937.

 

White, R. R., "Bubble Plate Column Design," Petroleum
Prgcessing, 147-54 (February, 1947) and 228-232 (March,
19 7 .

Zenz, F. A., "What Goes on Inside Bubble-Cap Towers,"
Chem. Eng., L4, No. 4, 169-173 (1952).

 

-42-

APPENDIX

 

 

 

 

 

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Actual Pressure, Psig.

TABLE VII.

Actual Pals...
Dead Weight
Tester

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REP 28 '59

 

 

 

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