OXYGENATION OF AQUEOUS BODIES
USING LIQUID OXYGEN-LOXINATION
by
T. D. Bath
William Garner
A. E. Vandegrift
Midwest Research Institute
Kansas City, Missouri 64110
for the
FEDERAL WATER QUALITY ADMINISTRATION
DEPARTMENT OF THE INTERIOR
Program 17050 EEY
- Contract 14-12-168
March 1970
J
MIDWEST RESEARCH INSTITUTE 425 VOLKER BOULEVARD, KANSAS CITY, MISSOURI,64Tl,0 ° AREA 816 561-0202
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ABSTRACT
An, experimental system was designed, constructed, and tested for
the introduction of oxygen in the liquid state (LOX) into a body of water
at 7° to 30°C. The sorption of LOX, both by static water columns and by
flowing water columns, was examined. Sorption efficiency and mass-transfer
coefficients were calculated.
Under experimental conditions investigated, these coefficients did
not appear significantly different from those observed for gaseous oxygen.
Water temperature, initial dissolved-oxygen concentration, and shear at the
point of oxygen injection were less significant in affecting the mass-trans-
fer coefficients than was gross water turbulence. The mass-transfer coeffi-
cients correlated with the corresponding Reynolds number.
ii
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TABLE OF CONTENTS
Abstract.
Introduction 1
Rationale 1
The Phenomenon 2
Scope and Objectives of the Program 4
Program Review 5
State of the Art Review 5
Equipment Design and Construction 6
Operating Procedures 13
Experimental Program . 14
The Experiments „ 15
Experimental Analysis 16
Data Groups - Their General Impact and Validity 21
Evaluation 30
Information From the Data 30
Economic Considerations 35
Overall Evaluation 38
Conclusions , „ „ 39
Appendix A - Scope of Work 41
Appendix B - Bibliography „ 46
List of Tables
Table Title Page
I Results of LOX Injection into a Seven-Foot Column of
Water, T = 20°C 23
II Results of LOX Injection into a Seven-Foot Column of
Water Equipped with Baffles, T = 20°C 23
III Results of LOX Injection into a 14-Foot Column of Water
with the Lower Portion of the Column Equipped with
Baffles, T = 20°C 24
IV Effect of Temperature on the Absorption of LOX 25
V Effect of Initial DO on Both Relative Absorption and Mass-
Transfer Coefficient, T = 20°C 27
VI Effect of Localized Stirring on Both Oxygen-Absorption
Efficiency and Mass-Transfer Coefficient, T = 20°C,
Initial DO > 0.5 ppm . 28
iii
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TABLE OF CONTENTS (Concluded)
List of Tables (Concluded)
Table Title Page
VII Factors Affecting LOX and Gaseous Oxygen Absorption .... 29
VIII Efficiency of Absorption of Oxygen in a Continuous Flow
System 30
List of Figures
Figure Title Page
1 Simplified Schematic of LOX Dissolving in Liquid Water. . . 3
2 Water-Flow Diagram for LOXination Equipment 7
3 Switching-Device Circuit Diagram 8
4 LOXination Equipment „ 9
5 Close-Up of LOX-Absorption Column 10
6 Nose Piece of First LOX Injector 11
7 Schematic of Injector and Associated Apparatus for Continu-
ous LOX-Injection Experiments „ . 12
8 Typical Curve of DO Versus Time for a Dynamic LOXination
Run 17
9 Dissolved Oxygen Content at Column Outlet 18
10 Rate of Concentration Change During Oxygen Absorption (The
Slope of This Line Is the Mass-Transfer Coefficient). . . 20
11 Correlation of Mass-Transfer Coefficient with Reynolds
Number, 30-Second Injection Period 31
12 Correlation of Mass-Transfer Coefficient with Reynolds
Number, 60-Second Injection Period 32
13 Correlation of Mass-Transfer Coefficient with Reynolds
Number, 120-Second Injection Period „ . . . 33
14 Cost of Pure Oxygen 37
iv
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INTRODUCTION
Rationale
One of the basic problems in water pollution control is that of
supplying dissolved oxygen (DO) to a body of water at sufficient rates and
in sufficient quantities to prevent septicity due to bacterial metabolism
of organic impurities. This problem can occur either in a sewage treatment
plant, or in a stream or river, when the organic load becomes so great that
the natural diffusion process, cannot supply the amount of oxygen required.
In such cases, artificial processes for increasing the DO concentration
can be used, including mechanical aeration methods. The present program
was initiated to investigate the possibility of using liquid oxygen (LOX)
to replace these aeration processes; i.e., using liquid oxygen as a source
of dissolved oxygen for aqueous bodies. We have designated this process
as "LOXination."
The rationale for considering LOXination in wastewater treatment
and for stream or impoundment aeration is as follows:
1. Usually the most economical form for transportation of oxygen
is the liquid state, LOX.
2. LOX is more dense than water. If slugs of adequate size are
injected into an aqueous body, they should sink to the bottom and thus
limit direct losses to the atmosphere.
3. LOX, when injected into water, could evaporate at rates that
would produce a higher pressure bubble than can be obtained by sparging of
gaseous oxygen; therefore, use of LOX could yield improved mass-transfer
rates.
4. Evaporation of LOX in an aqueous matrix should lead to lo-
calized cooling which would increase the driving force for mass transfer.
5. LOX, when injected into water, could impart increased
turbulence to the system, thus increasing the rate of solution.
6. If moderate sorption efficiencies (on the order of 50%) could
be achieved in field application, use of LOX for large aqueous bodies would
be cheaper than mechanical aeration.
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The Phenomenon
Liquid oxygen and liquid water cannot coexist except under very
artificial and extreme laboratory conditions. Any study of the transport
of LOX into water must of necessity concern itself with transient situa-
tions where it is questionable whether the LOX itself ever comes into direct
contact with liquid water.
Liquid oxygen has a density at -183°C of 1.142 g/ml. It would
be expected that LOX would sink in a body of water and form a pool at the
bottom from which it would evaporate and then dissolve. A report^-' of a
large dump of surplus LOX in the Houston ship canal advised that the LOX
sank to the bottom and dissolved without producing any surface ebullition.
Preliminary tests at MRI seemed to corroborate this report.
Once in contact with liquid water, LOX should rapidly evaporate.
The heat content of 0.31 ml of water at 20°C is sufficient to vaporize 1 g
of the LOX. The gas that would be produced by 1 g would occupy 230 ml at
-183°C and at 1 atm. Conversely, if the gas produced were confined to the
space occupied by the liquid, a pressure of 263 atm would be needed. The
actual system of vaporizing LOX in water surely involves a bubble of pressure
intermediate between 263 atm and the hydraulic head of the water body. As
the bubble expands, it must overcome the inertia of the surrounding water.
The exact formulation and solution of the kinetic equations that analyze
the system shown in Figure 1 are beyond the scope of this program. Heat
flows into the LOX according to the equation
-K A -
dt H 1 dx
where Q is the heat transferred in time "t", KJJ is the heat-transfer
coefficient, A, is the effective transfer area, and T is the temperature
difference across the distance "x". The amount of LOX evaporated is the heat
transferred divided by the latent heat, X
Oxygen transfers into the water according to the relation
-dOx _ f .
dt " KGA2(VPs)
where Ox is the amount of oxygen transferred into the water phase, KQ is
a mass-transfer coefficient, A^ is the effective area through which the
oxygen is transferred, P is the pressure in the gas envelope at time t,
and P is the vapor pressure of 02 at saturation.
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Q
Figure 1 - Simplified Schematic of LOX Dissolving in Liquid Water
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The accumulation of oxygen in the gas envelope is "n" of the
general gas equation, PV = nRT. Thus
PtV _ 1 dT
= - K^ KgA2(Pt-P )
RT X dx
where V is the volume of the gas envelope and, therefore, a function of
the radii of the LOX sphere and the gas sphere. Likewise, A, and An are
different effective areas, but both are dependent on the radius of the gas
sphere. The distance of the heat transfer, "x", is also a linear dimen-
sion. With further examination, it is recognized that P and T, being
related to V, are also related to the radius, as are the constants X,
KH and KG since they are functions of T . The result is a transcenden-
tal equation with no closed-form solution.
Nonetheless, if (1) heat transfer, (2) LOX boil-off, and (3) trans-
fer of oxygen from the gas envelope occur under high pressure, nonequilibrium
conditions (to be expected due to the inertia of the water), there should be
a more rapid solution of injected LOX than injected gaseous oxygen.
A similar argument can be made that the turbulence due to high
thermal gradients in the water surrounding a sphere of LOX in a gas envelope
would be greater than around a simple gas bubble.
Scope and Objectives of the Program
The program tasks can be separated into two broad areas: (1) in-
formation retrieval and generation, and (2) evaluation. The objective of
the first task area was to develop enough information, both through literature
review and experimentation, to permit us to perform the second task area
adequately: assessment of the appropriateness of LOX as an oxygen source in
oxygen-poor waters. The "Scope of Work" agreed upon by Midwest Research
Institute and the FWQA is attached as Appendix A which details the experi-
mental and evaluative objectives of the program more fully. This report
documents our efforts to fulfill the letter and the intent of the "Scope
of Work," and delineates the difficulties and extenuating circumstances
which we encountered in these efforts and which have led to our present
inability to perform a really definitive assessment in this report.
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PROGRAM REVIEW
State of the Art Review
A literature survey was conducted at the beginning of the program
to obtain as much information as possible pertaining to the injection of
liquid oxygen into water. This survey was continually updated during the
program. The particular key words used in the search include: sewage treat-
ment, aeration, mass transfer, liquid oxygen, and gaseous oxygen. We have
found that very few studies'have been conducted using pure gaseous oxygen,
or air enriched with oxygen, fpr increasing the DO content of aqueous solu-
tions. No studies were found in which liquid oxygen had been used for this
purpose.
The reviewed literature was divided into five groups: (1) pure
oxygen or enriched air, (2) mass-transfer coefficients, (3) transfer in
activated sludge processes, (4) effects of surface-active agents, and
(5) general. During the past decade, Amberg^/ studied reaeration of streams
with molecular oxygen, and McKinney^L' studied oxygen-enriched air for biologi-
cal waste treatment. All other reported work using pure gaseous oxygen was
done more than 10 years ago. References that are not cited in the text of
the report but that are considered relevant are included in the Bibliography
(Appendix B).
Few data v/ere available on the mass-transfer coefficient that might
be expected when pure oxygen or enriched air was used, and none were avail-
able for liquid oxygen. Several articles were obtained in which mass-trans-
fer coefficients were calculated for the transfer of oxygen from air. Also
obtained were several articles on the transfer of oxygen in activated sludge
processing, using both mechanical aeration and the diffused air process.
The effect of surface-active agents on the transfer of oxygen has received
a great deal of study because of the presence of these compounds in most
treatment facilities. Mancy and Okun— and EckenfelderJL' have all been
very active in this area.
Reprints of the most pertinent pieces of literature were obtained
at the beginning of the project. A bibliography of this literature is pre-
sented in Appendix B. This bibliography was added to as the program pro-
gressed, but in general, little of real pertinence to the program was
found.
Concomitant with this program, the FWQA has had work under con-
tract to investigate the potential of pure gaseous oxygen in secondary treat-
ment. This gaseous oxygen program has been conducted at- Batavia, New York,
by Union Carbide. The results of the Union Carbide program should help
evaluate the need for further investigation of LOXination.
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Equipment Design and Construction
Design basis. The design of the experimental apparatus used in
these studies was tailored so as
1. To provide experimental data over the range of process
variables specified in the "Scope of Work,"
2. To be reasonably easy to control and operate, and
3. To restrict costs to the budgeted amount in the contract.
This third item furnished the limiting constraint on the size of the ap-
paratus. This, in turn, specified that extremely low amounts of LOX be
injected in order to operate the system at reasonable sorption efficiencies.
Although we were unable to obtain information from LOX processors and han-
dlers regarding the design of devices to handle such low flows of LOX, it
was our feeling that the problem could be solved by the development of a
special LOX injection device. A description of the major components of the
apparatus, as well as a schematic flow diagram, an instrument circuit diagram,
and photographs of the completed apparatus, are all presented in Figures 2-5.
Construction. The fabrication and assembly of all of the major com-
ponents of the apparatus, except the LOX-injector device, did not present any
unusual difficulties. These injectors were used during the course of the
project. Schematic designs of the last two are shown in Figures 6 and 7.
The initial design used a vacuum jacket to maintain the oxygen in the liquid
state. Flowrate was controlled by a needle valve in series with a toggle-
type valve which was used to shut off flow (and also to remove ice formed
at the end of the injector). Tests with this device showed that the design
did not provide adequate insulation to guarantee that the injected LOX
would be vapor-free. This injector was then rebuilt so that the valves and
tubing that were in direct contact with the LOX were jacketed with a liquid-
nitrogen bath. This device would dispense LOX which seemed to be free of
vapor, although problems were encountered with the formation of ice on the
injector tip. Although some rather unusual procedures had to be used to
make this device operate (discussed below under Operating Procedures), it
was used during most the experimental runs described below.
Later in the program, there arose the need for a device that
would dispense LOX continuously into the water column. Since the injector
shown in Figure 6 developed leaks, it was simpler to construct a new device
that would incorporate in its design the experience of several months of
laboratory study. This third injector design consisted of several concen-
tric tubes. The inner tube carried LOX, the next two carried a continuous
stream of liquid nitrogen, and the liquid-nitrogen-containing tubes were
surrounded by insulation. Flow was controlled by the tip orifice and the
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WATER
OXYGEN
TRANSFER
COLUMN
L-X-VACUUM
DEOXYGENATOR
NITROGEN
SUPPLY
Figure 2 - Water-Flow Diagram for LOXination Equipment
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oo
• -AAA/-II——*
1 - »••>
f) 2W MHI
INTKRKITrER
CONTACTS
WH1/8LL-
OXYGEN ft WMI
THERMISTOR 6 BLK
_ OXYGEN 5 Will
THERMlSrOR 5 BLK
OXYCEN 4 WHI
THERMISTOR 4 BLK
OXYCEN 3 II WHI
CRN
^ THERMISTOR 3 BLK
OXYGEN 2 Will
II
o ' o
IIIKRMISTIIR 2 ItLK
>T| <• WHI
I I OXYGEN I W
THERMISTOR I BLK
Will f(;R\
n «~"
•1XYCKN RI.C'ORH \7 TK\IT KI-.l'OKI> \7 MXRkTr. Ri'.Ol'"
L*
Figure 3 - Switching-Device Circuit Diagram
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Figure 4 - LOXination Equipment
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10
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TEFLON NOSE PIECE
^J-LUfe
LOX-INJECTION LINE
r— OXYGEN BLEED LINE
T
• TOGGLE OPERATED PUSH ROD
x VACUUM JACKET
LOX-INLET VALVE ( IN OPEN POSITION )
Figure 6 - Nose Piece of First LOX Injector
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STAINLESS STEEL TUBE
THERMOCOUPLE
INSULATION (RUBATEX)
CENTERING
SPACER
LIQUID NITROGEN
LIQUID NITROGEN
LIQUID
NITROGEN
,—&
20 PSI
RELIEF
VALVE
LIQUID
NITROGEN
GAS O2
Figure 7 - Schematic of Injector and Associated Apparatus for Continuous LOX-Injection Experiments
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back-up pressure. A thermocouple was placed as close as possible to the
point where the LOX entered the water. A continuous flow of 25 g/min of
LOX into the water column could be maintained without icing until the LOX
reservoir was emptied. It is worthy of mention that we were not able to
develop a device that would permit the extremely low, LOX flowrates de-
manded by the dimensions of the rest of the apparatus.
Operating Procedures
The test system had been designed so that experimental runs could
be conducted over a wide range of variables; e.g., water flow from 0 to 31
gal/min and temperatures from 4° to 30°C. The second LOX injector had been
designed so that LOX injection rates could be varied from about 1 g/min up
to 40 g/min with either continuous or intermittent injection.
The DO content and temperature that were attained in the absorp-
tion column during an experimental run were monitored with DO and tempera-
ture probes which allowed measurement of both longitudinal and radial pro-
files. These probes were calibrated at the beginning of each day's experi-
mental runs. The automatic switching device (see Figure 3) was set so that
temperature and DO measurements were taken continuously at each longitudinal
position in the column. In this manner the entire column was scanned every
15 sec, with the measurement at each longitudinal position being of 2-sec
duration.
Before experimental runs were conducted, it was necessary to obtain
a supply of water with the desired DO content. This was done by deoxygenat-
ing tap water in a vacuum-stripping column and storing this water under a
nitrogen blanket in a 1,500-gal insulated holding tank. The desired initial
temperature was obtained by circulating the water from the holding tank
through the heater or chiller.
Experiments were conducted both with the water phase being static
and with the water flowing downward past the LOX injector. Static runs be-
gan by injecting LOX for a predetermined time interval at a predetermined
flow. Temperature and DO levels were monitored from before LOX injection
until no changes occurred in the DO profile,,
A dynamic run was begun by starting the water flow through the
column, adjusting to the desired flowrate, and allowing this flowrate to
equilibrate. After the water-flow regime had been equilibrated, LOX in-
jection was begun. The increase in DO content of the water in the column
was monitored until it returned to the same level as before LOX injection.
13
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The majority of the experimental runs were made using the in-
jector shown in Figure 6. Due to ice formation on the tip of this device,
it was necessary to follow an unusual procedure to initiate flow. The
needle valve which was used to control flow was opened wide since flow
of LOX would not start otherwise. Once flow was initiated, the valve was
throttled back to whatever position was necessary to give the flowrate
required for the experiment. Since the valve was out of adjustment for
a time interval that was brief in relation to the 30-sec or longer LOX-
injection period, it was initially felt that this procedure introduced
little experimental error. Closer examination of the data, however, re-
vealed that the initial slug of LOX put in by this procedure could be an
important fraction of the total LOX input. This information has caused
us to hold suspect a large number of the data taken on the program.
For the continuous runs that were conducted to compare the sorp-
tion of gaseous oxygen and LOX, the injector shown in Figure 7 was used.
LOX flow was started with the water surface below the tip of the injector.
Once steady LOX flow had been established, as indicated by the flow of ex-
haust gas (measured by a wet-test meter), the water column was raised to
the top of the apparatus; while LOX injection continued and the desired
water flow through the apparatus was set. Only with this procedure could
we prevent plugging of the LOX injector with ice. A thermocouple at the
injector tip demonstrated that LOX at -183°C was being ejected. Further
evidence for the injection of oxygen largely in the liquid state was the
magnitude of oxygen flow through the system. The tip orifice would not
have permitted this amount of gas flow with the pressure employed.
The LOX and water streams were maintained constant until the DO
in the exit flow showed a constant level. The exhaust flow of oxygen that
was indicated by a wet-test meter also indicated steady sorption conditions,
Experimental Program
Rationale. The purpose of the experimental program was to de-
termine the influence of several operating and system parameters on the
rate and efficiency of transfer of LOX into the aqueous phase. The in-
fluences of these system parameters were to be determined experimentally
by varying one system parameter while holding the others constant. Fac-
torial experimental design was employed because a thorough study of the
total number of experimental conditions would have been prohibitively
expensive.
Chronology of Experiments. As noted above, the construction of
the experimental system was accomplished with little difficulty with the
exception of the LOX-injector device. A modification of the original design
14
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produced what we felt was a satisfactorily operating device. After "check-
ing out" the system, we proceeded to obtain a large quantity of experimen-
tal data according to the statistical experiment plan. More than 300
experiments were conducted to study the effect of LOX flowrate, water
flowrate and LOX-injection time on oxygen sorption and transfer rate in:
1. The cylindrical column,
2. The column with cross-flow baffles installed throughout its
length,
3. The baffled column with an additional, small-diameter ex-
tension on top,
4. System (3) at variable-inlet water temperatures,
5. System (3) with variable-inlet water DO,
6. The cylindrical column (with and without the extension) having
an impeller mounted just superior to the LOX-injection point (a 4-in.
impeller rotated at 680 rpm by a 1/10 h.p. motor, and a 6-in. impeller
rotated by 1/3 h.p. motor at 1,720 rpm, were used at different times).
7. System (6) used to compare the sorption of LOX in relation
to gaseous oxygen.
As pointed out earlier (under Operating Procedures), suspicion
as to the reliability of the amount of injected LOX led us to conduct
continuous runs. A few runs were made with this system in an attempt to
compare sorption efficiencies for LOX with those for gaseous oxygen. This
was the last set of experimental measurements performed on the program.
Attention was then turned to an attempt to draw useful conclusions from
analysis of the data at hand.
THE EXPERIMENTS
In this section of the report, we will deal with the experimental
measurements themselves, their analysis and their validity. The data are
presented in tables that include all those experiments with a particular,
experimental apparatus arrangement or process variable.
15
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Experimental Analysis
Material Balances. The LOX injector, in all runs involving the
injection of slugs of oxygen, was situated 14 in. from the bottom of the
column with the tip in the center of the cross section. The DO content was
measured at six height positions in the column. The lowest measurement
point is of greatest importance to the dynamic runs because it indicates the
outlet DO content. Figure 8 shows a typical curve of time versus DO content
where the time is measured from the start of LOX injection. This particular
curve is for Run No. 22. To calculate the efficiency of absorption, the
area under the curve was determined, multiplied by the mass flow of water
and divided by the amount of LOX injected. The LOX-injection system was
calibrated by continuous flow. The DO probes were calibrated against air-
equilibrated water. The overall, oxygen material balance was generally
not checked by measuring the quantity of gaseous oxygen evolving from the
top of the sorption column until very late in the program when it became
apparent that the oxygen material balance was in question. The gaseous
oxygen flow was calibrated by weight-difference measurements and checked
with a wet-test meter.
Reproducibility. During all but the final phases of the experi-
mental program, replicate runs showed good precision. The results obtained
in three dynamic experiments, during which identical experimental conditions
were maintained, are shown in Figure 9. The plotted data are the DO level
as measured by the Clark oxygen electrode at the bottom station of the
absorption tower.
Near the end of the experimental period, it was discovered that
the techniques for injection were not those for which the calibration was.
made. The LOX-flow calibration in use was not valid. For this reason,
the columns of data on efficiency of oxygen absorption in the tables of
results are labelled as "relative efficiency."
A graphical technique was used to calculate the absorption ef-
ficiency. This technique involved determining the area under the curve
of dissolved oxygen versus time for a given run (see Figure 8). The units
of the area calculated in this manner are (ppm) x (sec). This area was
multiplied by the mass flowrate of water through the column to obtain the
total amount of oxygen absorbed during the experimental run. The oxygen
injected during the experiment was obtained by multiplying the LOX flow-
rate by the time of LOX injection. Thus, efficiency was calculated by
dividing the LOX injected into the amount of LOX absorbed.
Mass-Transfer Coefficient. These were calculated two different
ways. The first method used involves the rate of transfer from the oxygen
globule into the water, and the second involves a mass balance and a rate
16
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WATER FLOWRATE: 27 GAL/MIN
LOX FLOWRATE: 0.125 GM/SEC FOR 105 SECONDS
0
100
150
200
250
TIME AFTER LOX INJECTION, SECONDS
Figure 8 - Typical Curve of DO Versus Time for a Dynamic LOXination Run
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of transfer for the whole column. The differential equation that applies
to the first process is:
dt
= Ka(C -C) (1)
!•• s
where C = concentration of dissolved oxygen at time, t, in ppm,
t = time for transfer in hr,
C = saturation concentration of dissolved oxygen in water in
s
equilibrium with a pure oxygen atmosphere in ppm,
1C = mass-transfer coefficient per unit volume,
a = area through which transfer is effected. Since bubble size
cannot be determined, the product
1C a = effective mass-transfer coefficient per unit volume, is
determined. It has the unit, hr .
If K a is assumed constant, Eq. (1) can be integrated to yield:
ln(Cg-C) = -Kja-t + constant . (2)
The actual value of the mass-transfer coefficient is obtained by measuring
the slope of ln(Cg-C) plotted versus time as shown in Figure 10.
In the case of bulk mass-transfer, the equation that applies is
^ = KJa(C -C) (3)
dV x s
where N = mass transferred per unit time in Ib 2/hr
V = volume of solution into which the oxygen is transferred and
"1C" and "a" have the same significance as above.
19
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oS
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cS
Q
100
9
8
7
6
5
10
0
I
1
20
40
60 80
TIME, (sec)
100
120
140
Figure 10 - Rate of Concentration Change During Oxygen Absorption (The Slope
Of This Line is the Mass-Transfer Coefficient)
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The rate of transfer is related to the concentration change in a mass of
water by the equation:
dN _ L
dC " p (4)
where L = solution flowrate in Ib/hr
and p = solution density in Ib/ft .
Equations (3) and (4) can now be combined to yield
K*a(C -C)dV = - dC . (5)
X s P
By integrating from the initial to final state, Eq. (5) yields:
In
(Cs-Cf) L (6)
where Ci = initial DO in ppm and Cf = final DO in ppm
and V = volume of the transfer vessel in ft .
By rearranging, the expression for the bulk mass-transfer coefficient is
obtained in terms of measureable parameters:
(Cs-Ci) L
1C a = In — '~T7 - (7)
^ (c.-cf) pv
For most cases of calculating the mass-transfer coefficient, we
used Eq. (2). We have, however, checked these calculations by apply-
ing Eq. (7) to randomly chosen experiments.
21
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The equivalency of the two mass-transfer coefficients, K, a and
K'a is shown as follows:
N = AvC (8)
o
where A = the column cross-sectional area in ft
v = the average solution velocity through the column in Ib/hr •
This says that the amount of oxygen transferred per unit time is equal to
the amount of water passing through a cross-sectional area of the con-
tacting vessel in this time period multiplied by concentration of oxygen
dissolved.
Now
— = Av, but v = — or (where 1 is column height )• (9)
dC t
Since v is independent of N or C, v = -r- and Adi = dV, then
dN. _ dV
dC ~ dt ' (10)
By rearranging, we obtain — = — . Therefore from Eqs. (1) and (3)
dV dt
K^a(Cs-C) = Kj.a(C8-C) , (11)
Thus KLa = KLa .
Data Groups - Their General Impact and Validity
The data can best be grouped according to the type of experimental
system used. The experimental systems were categorized in the section
called "Experimental Program," and we will use the same groupings here.
Results of replicate runs were averaged when the data from the runs were in
close agreement.
22
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Group (a). The data are presented in Table I. One obvious result
was the low absorption efficiencies observed which led to a modification of
the apparatus so that longer contact times could be obtained. Mass-transfer
coefficients were not evaluated.
Group (b). The data are listed in Table II. They show that rela-
tive absorption efficiencies can be increased by baffling the exchange re-
gion and operating at relatively small, LOX/water, flow ratios. This was
to be expected. These data do give the reader a feel for the reproducibility
of the experiments. The calculated LOX mass-transfer coefficients are
comparable to those for gaseous oxygen transfer studies.
Group (c). The data in Table III indicate that some of the runs
operated at higher (up to 100%) "relative" efficiencies. The main reason
for this dramatic increase in efficiency is additional contact time due to
the extension of the column by a small-diameter, 7-ft glass tube on top of
the original column. Nearly all of the mass transport takes place in the
upper 7 ft of the column where all of the undissolved oxygen is in the gas
phase. Thus, while it is no doubt interesting that this enhanced absorption
efficiency there is little in data of this sort to prove that LOX possesses
significant practical advantages over gaseous oxygen. At high efficiencies,
the question of the accuracy of the material balance becomes an important
factor. Earlier in the report it was noted that the term "relative" effi-
ciency was being used due to irregularities in operating procedure for the
LOX-injection device. An attempt was made late in the project to "cali-
brate" this injection technique with the following result (95% confidence
level):
LOX
Actual (8) = 8'2 + °'77 Calibrated <*> ~ 3'°
The variance associated with this equation is so large that it was not
deemed worthwhile to update the LOX-flow and the corresponding LOX absorp-
tion-efficiency values in any of the data groups. Thus, we can place rela-
tively little reliability on the efficiency data, other than for comparative
purposes. However, the calculation for mass-transfer rate is based only on
liquid-phase data, and these numbers are felt to be useful. These data
provide the basis for the correlation of the mass-transfer coefficient with
the Reynolds number developed later.
Group (d). The data in Table IV suffer from the same uncertain-
ties as the previous data. They do show, however, that any temperature
effects which may exist have no noticeable effects on the transfer co-
efficient over the range of temperatures studied. (Part of Group (c ) data
are reproduced for comparison purposes.)
23
-------
TABLE III
RESULTS OF LOX INJECTION INTO A 14-FOOT COLUMN OF WATER WITH THE LOWER
PORTION OF THE COLUMN EQUIPPED WITH
Flowrate
Run
100-102
103-104
106-109
110-111-122
112-114
115-117
118-120
123-125
126-127
129-131
132-134
135
136-138
139-141
142-145
146-148
151-153
154, 155, 159
156-157
160
161, 163, 164
162, 165
166, 167
168, 170
171,172
173-174
174-175
177-178
228
230-231
229, 232
233-234
235
236
LOX
(g/min)
3
3
3
12
12
12
12
12
12
12
3
3
12
12
12
3
3
3
12
12
12
12
3
3
3
12
12
3
3
9
6
3
6
9
Water
(gal/mln)
15
15
15
31
15
15
15
0
0
0
0
0
20
20
20
20
20
20
10
10
10
10
10
10
10
5
5
30
0
0
0
0
0
0
BAFFLES. T = 20°C
Relative
Injection Absorption
Time
(sec)
30
60
120
30
30
60
120
30
60
120
120
805
30
60
120
30
60
120
30
30
60
120
30
60
120
30
60
30
120
120
120
120
120
120
Efficiency
(%)
56.2
49.2
44.7
56.0
18.7
15.6
14.4
4.3
5.3
2.1
14.5
(steady 8.1
state)
20.2
18.9
18.6
100.0
60.0
42.7
8.9
10.3
11.4
10.8
30.4
36.7
30.0
7.5
5.2
100.0
6.2
3.4
4.7
8.6
12.0
3.4
Mass-
Transfer
Coefficient ,
K(hr-l)
3.66
4.49
5.02
6.38
3.71
5.09
6.98
5.22
5.56
4.55
3.00
2.95
2.95
6.00
8.87
3.18
3.06
4.96
1.13
0.63
1.39
3.50
0.70
1.53
3.06
0.66
1.20
6.43
2.2
3.4
2.1
3.1
3.2
4.4
25
-------
TABLE IV
EFFECT OF TEMPERATURE ON THE ABSORPTION OF LOX. DUAL COLUMN
WITH
14 -FOOT
HEAD, LOWER COLUMN BAFFLED.
Flowrate
Run
237-238
239-240
241-242
243-244
245-246
247-248
249-250
251-252
253-254
255-256
257
258
259-260
261-262
263
264
146-148
151-153
154, 155,
159
166, 167
168, 170
171, 172
Temperature
30
30
30
30
30
10
10
10
10
7
7
7
10
10
10
10
20
20
20
20
20
20
LOX
(g/min)
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
Water
(gal/min)
20
20
20
10
10
20
20
20
10
20
20
20
10
10
10
10
20
20
20
10
10
10
Injection
Time
(sec)
30
60
120
30
120
30
120
60
30
30
60
120
120
120
30
60
30
60
120
30
60
120
Relative
Absorption
Efficiency
(%)
4.1
6.5
8.2
0.58
3.0
3.9
5.2
3.7
0.70
4.0
4.5
5.3
2.6
5.1
0.83
1.3
3.18
3.06
4.96
0.20
1.53
3.06
Mass -
Transfer
Coefficient,
KOir-1)
100.0
79.5
59.0
38.6
39.8
78.0
61.0
57.0
37.0
100.0
78.0
57.0
33.3
31.5
48.0
31.7
100.0
60.0
42.7
30.4
36.7
30.0
26
-------
Group (e). The data in Table V show the effects of higher initial
DO on mass transfer and absorption efficiency. No apparent effects were
found.
Group (f). The data in Table VI were obtained to compare the
effects of (1) localized turbulence created by stirring at the point of
LOX injection with (2) the turbulence throughout the body of the column
due to flow and baffling. These data led to the interpretation that
localized turbulence is less effective.
Group (g). The data in Table VII are intended to compare the
transfer of LOX with the transfer of gaseous oxygen. If the absorption
efficiencies are ignored, there is a general (but not consistent) trend
in mass-transfer coefficient favoring LOX over gaseous oxygen. This may
be due in part to higher mass inputs for LOX than for gaseous oxygen.
Group (h). The data in Table VIII are the result of experiments
run with continuous injection of LOX into a flowing stream of water. The
intent of the experiments is to compare LOX with gaseous oxygen. The
oxygen flowrates necessary to sustain continuous flow were too high in
relation to maximum water flows to obtain high absorption efficiencies.
27
-------
TABLE V
EFFECT OF INITIAL DO ON BOTH RELATIVE ABSORPTION AND
MASS-TRANSFER COEFFICIENT, T = 20°C
Run
265-266
267-268
269-271
272-274
275-276
277-278
146-148
151-153
154, 155, 159
3
3
3
3
3
3
3
3
3
Relative Mass-
Injection Initial Absorption Transfer
LOX Water Time DO Efficiency Coefficient,
(g/min) (gal/min) (sec) (ppm) (%) K(hr-1)
20
20
20
20
20
20
20
20
20
60
60
60
60
A/30
60
30
60
120
5.0
5.0
4.67
3.75
3.0
3.0
88.0
76.0
65.0
64.0
91.0
73.0
< 0.5
< 0.5
< 0.5
100.0
60.0
42.7
5.4
5.7
4.4
4.8
4.8
5.6
3.18
3.06
4.96
28
-------
TABLE VI
EFFECT OF LOCALIZED STIRRING ON BOTH OXYGEN-ABSORPTION EFFICIENCY AND
N>
MASS -TRANSFER COEFFICIENT, T =
Run
Top Column Off
279-280
281-282
283-285
303-304
306-308
309-311
Top Column On
286-287
288-289
290-291
292
295 & 299
296 & 298
300-302
342-344
347-348
349-351
360-362
363-364
LOX
Rate
(e/min)
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
Water
Rate
(gpm)
(Head = 7 ft)
0
0
0
0
0
0
(Head = 14 ft)
0
0
0
10
10
10
10
0
0
0
5
5
Injection
Time
(sec)
30
60
120
30
60
120
30
60
120
30
60
120
30
30
60
120
30
120
20 °C. INITIAL DO > 0.5 PPK
Size
(in)
4
4
4
6
6
6
4
4
4
4
4
4
4
6
6
6
6
6
Impeller
(rpm)
Baffles removed
680
680
680
1,720
1,720
1,720
680
680
680
680
680
680
680
1,720
1,720
1,720
1,720
1,720
Relative
Absorption
Efficiency
a)
51.5
39.7
32.4
70.0
29.0
23.0
38.8
26.4
26.5
56.0
54.0
47.0
54.0
76.0
85.0
88.0
106.0
133.0
Mass-Transfer
Coefficient
K(hr"1)
7.7
6.3
8.7
2.5
1.4
2.2
3.4
3.5
5.9
1.7
5.2
8.0
1.1
2.8
6.5
12.6
29.0
65.0
-------
TABLE VII
FACTORS AFFECTING LOX AND GASEOUS OXYGEN ABSORPTION
Amount of
Oxygen
Injected
(g)
1.5
1.5
1.5
3.0
3.0
6.0
6.0
6.0
6.0
6.0
12.0
12.0
24.0
24.0
Flow
of
Oxygen
(g/min)
3
3
3
• 3
3
3
3
3
12
12
12
12
12
12
Period
of
Injection
(sec)
30
30
30
60
60
120
120
120
30
30
60
60
120
120
Water
Head
(ft)
7
14
14
7
14
7
14
14
7
14
7
14
7
14
Water
Flow
(gal/min)
0
0
5
0
0
0
0
5
0
0
0
0
0
0
Relative
Percent
LOX
70
76
106
29
85
23
88
133
16
31
16
35
-
27
Efficiency
Absorbed
Gas
46
50
48
33
48
32
45
44
23
33
16
32
10
24
, Mass-Transfer
Coefficient
LOX
2.5
2.8
29.0
1.4
6.5
2.2
12.6
65.0
1.2
5.5
5.0
11.7
-
21.3
, K(hr-l)
Gas
1.3
2.0
18.0
2.0
3.1
4.2
4.8
22.0
3.8
7.0
5.8
10.5
6.3
16.5
-------
TABLE VIII
EFFICIENCY OF ABSORPTION OF OXYGEN
IN A CONTINUOUS FLOW SYSTEM
Oxygen Flow = 25 g/min
LOX Absorption Gaseous Oxygen Absorption
Water Flow 02* DO** 02* D0**
(gpm) JS1 • XSL (%) (%)
31.0 15.0 14.0 13.0 14.0
5.0 5.0 1.6 10.0 1.1
2.0 ' 1.0 0.6 0 0.6
* 0~ means calculation from gaseous oxygen not absorbed by the water
column, measured instead by wet-test meter.
** DO means calculation based on dissolved oxygen in effluent water stream
of absorption tower.
EVALUATION
Information From the Data
There is little to be gained from any attempt to correlate the
data on absorption efficiencies with any of the system parameters because
of the problems mentioned earlier. However, some qualitative judgments can
be made. The data on mass-transfer coefficients have greater utility. A
quantitative correlation between the mass-transfer coefficient and the proper-
ties of the system can be obtained by resorting to dimensional analysis.
Dimensional analysis indicates that the dimensionless mass-transfer coeffi-
cient (the Sherwood number) should be a function of the Reynolds number (Re)
and the Schmidt number (Sc). Since the Schmidt number contains parameters
which involve properties of the fluids only, it will not enter into the
correlation because we have been dealing with the same fluids throughout
these experiments. It is therefore reasonable that the mass-transfer co-
efficient should correlate with the Reynolds number alone. As mentioned
earlier, the degree of turbulence in the system was increased by lengthening
the injection time; because of this fact, an attempt was made to obtain
separate correlations for the three most commonly used injection periods of
30, 60 and 120 sec. The correlations which were obtained are shown in
Figures 11, 12, and 13.
31
-------
u>
t
LJ -
m|05
2
Z)
olO'
UJ
cr
I03
30-SECOND INJECTION
i 8 I I I I
O.I 1.0 10.0 100.0
MASS-TRANSFER COEFFICIENT (HR'1)
Figure 11 - Correlation of Mass-Transfer Coefficient with Reynolds Number, 30-Second
Injection Period
-------
U)
t
cr
^ *
m |05
en
•»
Q
OlO'
LU
o:
I03
60-SECOND INJECTION
O.I 1.0 10.0 100.0
MASS-TRANSFER COEFFICIENT (HR'1)
Figure 12 - Correlation of Mass-Transfer Coefficient with Reynolds Number, 60-Second
Injection Period
-------
t
a:
UJ .
OQ|05
CO
•»
Q
dio
LJ
cr
ICH
120-SECOND INJECTION
i i i i i i\jn
i i
I 1 I I I I t 1 I I
O.I 1,0 10.0 100.0
MASS-TRANSFER COEFFICIENT (HR'1)-
Figure 13 - Correlation of Mass-Transfer Coefficient with Reynolds Number, 120-Second
Injection Period
-------
Since in some cases the column had two different Reynolds num-
bers for each experimental run (due to the different diameters of the two
column sections), there is some question as to which Reynolds number corres-
ponds to the mass-transfer coefficient that was calculated. At any given
mass flowrate, the Reynolds number in the top section of the column is four
times the Reynolds number in the lower section of our column. By using the
second calculational method discussed in the previous section, it can be
shown that the Reynolds number which should be used in correlating the mass-
transfer coefficients corresponds to the number in the lower column. It can
also be shown that the ratios of the mass-transfer coefficients for the upper
versus the lower portions of the column are equal to the ratio of the volumes
of the upper and lower sections. The proof is as follows:
For a fixed initial and final DO, mass flowrate, and density, the
ratio of 'Eq. (3) for the top column section to Eq. (3) for the bottom column
section is
<*LaV>T
o
(KLaV>Bottom
therefore
K_ 3 ~ K_ B. B 011 OTTl
Top
In other words, if all oxygen transfer occurred in the top sec-
tion, but the concentration change used to calculate the mass-transfer
coefficient were measured in the bottom section, the actual mass-transfer
coefficient would be the one calculated, multiplied by the ratio VR /
VTop '
When the mass-transfer coefficients are increased by the ratio of
the volumes as described in the preceding paragraph, they fall on the cor-
relating line drawn from the original data. With the correlation shown in
Figures 11, 12 and 13, it will be possible to extend the range of usefulness
of these data by extrapolation. In other words, it will be possible to pre-
dict what the mass-transfer coefficient for a system similar to the one used
would be if the Reynolds number were, for example, 100,000.
It is not surprising that these data correlate strongly with the
Reynolds number. The same sort of correlation would be expected for gaseous
oxygen. In fact, previously published mass-transfer data would lead one to
expect a mass-transfer correlation of the form:
35
-------
f(Re, Sc) (see Iberall and Corderi/)
No gaseous data have been taken in a flowing water system similar to the one
we have used, so it is not possible to obtain a comparison between mass trans-
fer coefficients.
We can, however, compare with a correlation for wetted wall columns
to determine if the mass-transfer coefficient in the gaseous system would be
of the same order of magnitude as that for our LOX system. The correlation
is
(0.81)c 0.44
KLa = [_(0.023)(^)(Dvf]Re(°-81)Sc
where
Re = Reynolds number
Sc = Schmidt number
D = Diameter of wetted wall column
DV = Diffusion coefficient of 02 in water
For a Reynolds number of 10,000 in a reasonably sized column, 1C a zx 3 hr
which is the same order of magnitude as we have found.
Economic Considerations
The cost of pure oxygen to the consumer is predicated on the rate
of consumption and distance to source of production. An economic break-
point exists at the consumption rate of about 25 tons/day since at this
point, when no other untoward economic factors occur, a separation plant
would be erected at or near the site of consumption.
If the demand were over 25 tons/day, the oxygen would be supplied
as gaseous oxygen by pipeline. On the other hand,smaller quantity consump-
tion of oxygen could not economically support a plant and thus the oxygen
would be transported to the site of consumption as LOX.
Four major, industrial gas suppliers were queried as to the
pricing schedule by requesting the cost for supplying oxygen to 10 differ-
ent locations. Four scales of oxygen requirements, subsequently established,
were somewhat related to the communal BOD load. These are listed below:
36
-------
Oxygen Requirements
Location (Ib/day)
Chicago, Illinois 200,000
Kansas City, Missouri 200,000
Buffalo, New York 200,000
Athens, Georgia 25,000
Corvallis, Oregon 25,000
Springfield, Massachusetts 25,000
Carlyle, Illinois 5,000
Henderson, Kentucky 5,000
Las Cruces, New Mexico 1,000
Show Low, Arizona • 1,000
The results of the responses are presented in Figure 14. The pric-
ing schedules of the four companies are quite close to each other. Two of
the companies quote LOX prices that include rental of storage facilities,
while the other two companies quote lower LOX prices with additional costs
for rental of storage tanks. All four suppliers would have the customer
provide a concrete foundation and fencing at his own expense. The sites
with lower level LOX consumption would have storage capacity with several
days' consumption at hand. Reorders are usually placed when the storage
facility has been drained to about 30% of capacity.
LOX is transported by truck and tank car. Quoted prices include
delivery within a 100-mile radius of the separation plant. In some of the
more remote locations of the West, the price of LOX could double due to
delivery costs. Delivery costs include both transportation and evaporation.
LOX can be piped, but costs of $10 to $30/linear ft for cryogenic piping
limit the distance of this transport method.
When oxygen is produced by on-site liquefaction and distillation
of air, the delivered product is gaseous oxygen since the heat of vaporiza-
tion of the liquid can be used to cool the air that is to be liquefied.
Tonnage oxygen costs drop to $10/ton only at the level of 1,000 tons/day
consumption. Only metropolitan New York City would produce domestic
wastes with a BOD requiring this amount of oxygen.
The minimum price of pure oxygen is related to the cost of power
by the relationship that 350 kwh is required for the production of 1 ton of
pure oxygen. The Kansas City industrial rate of slightly less than $0.02/kwh
sets a floor of about $7/ton oxygen. Only in plants producing a very high
tonnage of oxygen daily does this power requirement become the major factor
in the cost of pure oxygen in relation to capital costs and other operating
costs.
37
-------
10,000,000,-X
1,000,000
> 100,000
Q
O£.
UJ
O.
1/1
O
Z
o
Q-
z
o
z
o
3 4 5 6 7 8
CENTS PER POUND
COST OF PURE OXYGEN
Figure 14 - Cost of Pure Oxygen
10 11
38
-------
Speece— has conducted a modeling study of the solution of diffused
oxygen in water. Under certain conditions, 100% absorption was predicted.
Some power must be expended to accomplish this, but if the operating power
costs are assumed small in relation to the cost of the oxygen, oxygenation
may be compared with alternative processes as seen below:
Oxygen
Transfer Rate Cost/lb 02
Process (Ib/kwh) (2
-------
8. Varying the water temperature from 7° to 30°C had no apparent
effect on the absorption efficiency.
9. The initial DO content of the water did not appreciably affect
the mass-transfer coefficient.
41
-------
APPENDIX A
SCOPE OF WORK
FEDERAL WATER QUALITY ADMINISTRATION
CONTRACT 14-12-168 WITH THE MIDWEST RESEARCH INSTITUTE
42
-------
OXYGENATION OF AQUEOUS BODIES WITH
LIQUID OXYGEN. "LOXination"
The contractor will provide the necessary personnel, materials,
and facilities, and will exert his best efforts to perform the research and
engineering development studies that will determine the requisite parameters
for the oxygenation of aqueous bodies with liquid oxygen (LOX). A detailed
chronological description of the studies that will be conducted is presented
below:
1. The design of the experimental apparatus that will be used to
study the interaction of LOX with aqueous bodies will be completed and work-
ing drawings will be prepared. The preliminary design that has already been
completed calls for construction of a tower comprising multiple sections of
12-in. diameter borosilicate glass (Pyrex Double Tuff), separated by narrow
sections of 316 stainless steel. The glass sections will permit visual and
photographic observation of the phenomena occurring within the column, while
the stainless steel sections will permit the introduction of liquid streams
as well as the instrumentation necessary for these studies. The column has
been designed to allow pressurization to 30 psia. The liquid oxygen inlet
lines will be insulated by use of vacuum-jacketed tubing. A bleed line will
be placed just at the inlet to the column to ensure that the oxygen is intro-
duced into the column in the liquid state.
The design factors remaining to be completed include the structure
necessary to support the apparatus, the water pumping equipment, and speci-
fications for the insulation of the lower end of the column.
2. The experimental apparatus with its appurtenances will be con-
structed in our shops. It will be installed in a laboratory containing
safety features that will minimize hazards associated with the handling of
LOX. Hazards to be recognized in handling LOX include: (1) explosive mix-
tures which form when LOX comes in contact with reducing substances, (2)
burns and frostbite which may occur when low-temperature LOX or lines trans-
mitting LOX come in contact with tissue, and (3) the extremely high pres-
sures which can develop in a closed system if the system is allowed to warm
up. To minimize these hazards we shall exercise scrupulous housekeeping,
protect handlers of LOX with face shields and insulated gloves, and ensure
that adquate bubble-off lines are built into each piece of apparatus. The
laboratory will be well ventilated to ensure that unusually high levels of
gaseous oxygen do not build up, and the additional precaution of an atmospheric
oxygen monitoring meter with safety alarm will be installed.
3. When completed, the experimental apparatus will be tested for
performance according to the design criteria of (1) hydraulic flow, (2) ability
43
-------
to deliver oxygen in the liquid form, (3) minimization of heat input from
external sources, and (4) performance of the associated instrumentation.
4. The first studies will be conducted by measuring the effects
resulting from batch injection of LOX into a static water column. This is
one of four possible variations that also include batch injection of LOX
into a flowing water column, continuous injection of LOX into a static water
column, and continuous injection of LOX into a flowing water column. These
latter three conditions will be evaluated in subsequent experiments during
these first studies.
The LOXination phenomena will be studied by making visual and
photographic observations of the interface between the liquid water and the
liquid oxygen. This information will help establish the actual mechanism
of oxygen transfer. Additionally, mass transport phenomena will be studied
by establishing oxygen concentration profiles by means of polarographic
oxygen probes placed strategically throughout the apparatus. Heat transfer
phenomena will be studied by measuring temperature profiles with Chromel-
Alumel thermocouples.
The important process variables to be studied are:
(a) Temperature: The effect of temperature will be deter-
mined by employing water with initial temperatures of 4°, 10°, 20°, and
30°C. These temperatures are representative of the most probable range of
temperatures to be encountered in polluted natural waters or wastewater
streams.
(b) Initial Dissolved Oxygen Level: Inlet water with an ini-
tial dissolved oxygen s^evel of 0, 10, 20, and 407» of saturation will be
studied.
(c) System Pressure: The column will be pressurized either
by employing excess gas pressure or by increasing the hydrostatic head.
Pressures of 1, 1.5 and 2 atmospheres will be studied.
(d) Geometry of the Column: The effect of geometry will be
evaluated by using length-to-diameter ratios of 2, 6, and 10. Baffles will
be introduced to study their effect on changes in flow pattern and the re-
sultant changes in the rate of oxygenation.
(e) Water Flow Rate and Column Height: The relationship be-
tween oxygenation and both residence time and flow regime will be determined
by measuring the rate of oxygenation at various flow rates and column heights.
The residence time, which is the ratio of the column height to the average
velocity, will be selected so that the dimensionless parameter, V/Lk , will
44
-------
have the values of 0.25, 1.0, and 4.0.' In this parameter, V is the
average velocity in ft/sec, L is the height of the contacting vessel in
ft., and k is the rate constant for the specific rate of absorption in
sec'l.
Flow regimes will be selected so that the effect of laminar,
transition, and turbulent flow will be measured. To achieve these types of
flow, the flowrate will be varied to give Reynolds numbers of 0, 500, 2500
and 5000.
(f) The Mechanism of Creating the LOX-Liquid Water Interface:
This mechanism will be elucidated by adding LOX at various points in the
water column and observing the physical breakup of the LOX stream or slug.
Various dispersal devices such as impellers, impingers and multiorifice
distributors will be tested for their ability to produce optimum-size LOX
globules. The criterion for optimum size will be the maximum absorption of
oxygen in the shortest time period.
5. The results of all of the experiments which are described
above will be tabulated, correlated, and interpreted to establish relation-
ships among the numerous system variables and the phenomena involved in oxy-
genation of aqueous bodies by LOX. The experimental apparatus will then be
modified, if necessary, to produce the most efficient addition of LOX to
aqueous bodies.
6. The requisite parameters for the oxygenation by LOX of water
from naturally occurring aqueous bodies will be determined. Among the
waters that will be studied are, (a) Missouri River water, (b) effluent from
the Blue River Sewage Treatment Facility at Kansas City, Missouri, (c) real
or synthetic sewage treatment plant effluents that contain a higher than
usual level of LAS, and (d) industrial effluents such as would be encountered
in the pulp and paper industry.
7. The interaction of LOX with sludges from domestic wastewater
and natural benthic sludges will also be measured. This interaction is im-
portant because in many applications of LOXination, the bottom of the LOXina-
tion vessel may be a natural river bottom or a sludge-holding tank, in which
the bottom will be covered with dispersed organic material.
8. When all of the design parameters have been established by
laboratory and field investigations, a precise economic comparison of LOXina-
tion with other artificial aeration techniques will be prepared. The results
of this analysis along with the field testing will determine whether a large-
scale demonstration project is feasible.
45
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9. Throughout the course of the engineering study, due attention
will be given to the eventual application of LOXination to field sanitary
engineering practice by continuous recognition both of its technical feasi-
bility and the economic requirements. Although this study has been designed
to examine the application of LOXination to the abatement of water pollution,
any phenomena which affect air quality or land values are important factors
to be recognized and evaluated. Thus, the effect of large-scale LOXination
on the total environment will be an important part of the study.
10. The senior investigators on the project will recognize the
necessity to keep abreast of advancements in associated scientific and
engineering fields by a regular program of literature surveillance, attendance
at related scientific and technical meetings, and personal contact with other
technical people in the field of sanitary engineering.
Close liaison will be maintained between the senior investigators
and the Project Monitor as well as other interested personnel of the FWPCA.
Informal monthly letter reports will be sent to the Project Monitor. A
Final Report will be issued following completion of the project in numbers
and in the style as requested by the FWQA.
46
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APPENDIX B
BIBLIOGRAPHY
47
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REFERENCES CITED
1. McGriff, S., Washington, D. C., private communication.
2a. Amberg, H. R., L. F. Cormack, W. Funk, A. S. Rosenfeld and R. 0. Blosser,
"Reaeration of Streams with Molecular Oxygen," Ind. Water Eng., 4 (2)
15 (1967).
2b. Amberg, H. R., D. W. Wise and T. R. Aspitarte, "Aeration of Streams with
Air and Molecular Oxygen," Tappi. 52, 1866 (1969).
3. McKinney, R. E., private communication of data obtained in the study by
J. T. Pfeffer and R. E. McKinney, "Oxygen-Enriched Air for Biological
Waste Treatment," Water Sewage Works. U2, 381 (1965).
4. Mancy, K. H., and D. A. Okun, "The Effects of Surface-Active Agents on
Aeration," J. Water Pollution Control Federation. 37, 212 (1965).
5. Iberall, A. S., and S. Z. Cardon, "Aeration Mass Transfer Related to
Reynolds Number," J. Appl. Chem. (London). 16 (2), 64 (1966).
6. Speece, R. E., "The Use of Pure Oxygen in River and Impoundment Aeration,"
paper presented at 24th Purdue Industrial Waste Conference, May 8, 1969.
ADDITIONAL PERTINENT REFERENCES
Pure Oxygen or Enriched Air
"High-Purity Oxygen in Biological Sewage Treatment," W. E. Budd and F. F.
Lambeth, Sewage Ind. Wastes, 29. 237 (1957).
"Absorption of Oxygen in Bubble Aeration," C. E. Carver, Biological Treat-
ment of Sewage and Industrial Wastes: Vol. I, Aerobic Oxidation, Reinhold
Publishing Corp., New York (1956).
Mass-Transfer Coefficients
"Physical Rate Processes in Industrial Fermentation. II. Mass-Transfer
Coefficients in Gas-Liquid Contacting with and Without Mechanical Agi-
tation," P. H. Calderback, TranstjInst. Chem. Engrs.London, 37, 173 (1959),
"Nomograms to Calculate Dissolved-Oxygen Contents and Exchange (Mass-Trans-
fer) Coefficients," I. C. Hart, Water Res.. 1, 391 (1967).
48
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"Pressure Drop and Heat and Mass Transfer for Countercurrent Liquid-Gas
Flow in Packed Columns," H. Scrader, Kaeltetechnik. 10, 290 (1958).
"Theoretical Concept of Oxygen Transfer in a Gas Bubble Aeration System,"
C. C. Poon, Water Sewage Works. 113, R-200 (1966).
Transfer in Activated Sludge Processes
"Oxygen-Transfer in the Biological Treatment of Sewage," S. Aiba et al.,
Air Water Pollution. 5 (2-4), 103 (1963).
"Relation Between Dissolved Oxygen Concentration and Oxygen Utilization
Rates in Activated Sludge Waste Treatment," G. F. Bennett and L. L. Kempe,
Chem. Eng. Progr.. Svmp. Ser. 63. 78, 171 (1967).
"Oxygenation from Diffused Air in Aeration Tanks," K. Bewtra and R. Nicholas,
J. Water Pollution Control Federation. 36, 1195 (1964).
"0-Transfer in the Activated-Sludge Process," A. L. Downing and A. G. Boon,
Air Water Pollution. 5 (2-4), 131 (1963).
"Diffused Air Oxygen Transfer Efficiencies," P. F. Morgan and J. K. Bewtra,
Adv. Biol. Waste Treat.. Proc. Conf.,3, 181 (1963).
"Influence of Turbulence on the Activity of Activated Sludge Floes," L. Hartman,
and G. Laubenberger, J. Water Pollution Control Federation, 40, 670 (1968).
"Field Studies of Oxygen Utilization in High Rate Activated Sludge," W. G.
Ahrens, M. J. Hammer and J. M. Nicholson, Univ. of Kansas. Bull. Eng.
Arch. No. 58, Trans. 17th Annual Conference on Sanitary Eng. (1968).
"Oxygen Transfer in Biological Systems," G. F. Bennett and L. L. Kempe,
Purdue Univ.. Eng. Bull.. Ext. Ser. Nojt 129, 435 (1965).
"Preliminary Investigations into the Effect of Oxygen Tension on Biological
Sewage Treatment," D. A. Okun and W. R. Lynn, Biol. Treat. Sewage Ind.
Wastes, Pap. Conf.. 1, 192 (1956).
"Surface Aerators for Absorption and Desorption of Gases into Water and
Liquid Waste," A. A. Kalinske, Water Sewage Works. 115, 33 (1968).
"Oxygenation of Water by Bladed Rotors," J. K. Baars and J. Muskol, Research
Institute for Public Health TNO. Netherlands. Report No. 28 (1969).
49
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"Relationship of Activated Sludge Bulking to Oxygen Tension," M. N. Bhalta,
J. Water Pollution Control Federation. 39, 1978 (1967).
Effects of Surface-Active Agents
"Effect of Various Organic Substances on Oxygen Absorption Efficiency,"
W. W. Eckenfelder, L. W. Raymond and D. T. Lauria, Sewage Ind. Waste, 28^,
1357 (1956).
"Effects of Surface-Active Agents on Oxygen Bubble Characteristics," J. J.
McKeown and D. A. Okun, Air Water Pollution, 5 (2-4), 113 (1963).
"The Effect of Some Organic Substances on Oxygen Absorption in Bubble Aera-
tion," S. A. Zieminski, C. C. Goodwin and R. S. Hill, Tappi. 43, 1029 (I960).
The Effect of Pure Oxygen on Microorganisms
"The Growth of the Bacillus tuberculosis and Other Microorganisms in Dif-
ferent Percentages of Oxygen," B. Moore and R. S. Williams, Biochem. J..
4, 177 (1908).
"The Growth of Various Species of Bacteria and Other Microorganisms in At-
mospheres Enriched with Oxygen," B. Moore and R. S. Williams, Biochem. J..
5, 181 (1911).
"The Effect of Atmospheres Enriched with Oxygen Upon Living Organisms, (a)
Effects Upon Microorganisms, (b) Effects Upon Mammals Experimentally
Inoculated with Tuberculosis, (c) Effects Upon the Lungs of Mammals, or
Oxygen Pneumonia," A. Adams, Biochem. J.. 6, 297 (1912).
"Influence of High Partial Pressures of Oxygen Upon Bacterial Cultures,"
H. T. Karsner, H. T. Brittinham and M. L. Richardson, J. Med. Res., 39,
83 (1924). . ~~
"Effect on Virulence of Bact. Aertrycke of Cultivation in Atmospheres Con-
taining Varying Proportions of Oxygen," G. S. Wilson, J. Hyg., 30, 433
(1930).
"The Effect of Atmospheres of Hydrogen, Carbon Dioxide, and Oxygen, Respectively,
and of Mixtures of These Gases on Growth of Bacillus subtilis," P. P. Levine,
J. Bacteriol.. 31_, 151 (1936).
"Aeration Requirements for the Growth of Aerobic Microorganisms," C. G. Smith
and M. J. Johnson, J. Bacteriol.. 68, 346 (1954).
50
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"Effect of Oxygen Supply Rates on Growth of Escherichla coll. I. Studies on
Unbaffled and Baffled Shake Flasks," L. E. McDaniel, E. G. Bailey, and A.
Zimmerli, Appl. Microbiol.. 13, 109 (1965).
"Effect of Oxygen Supply Rates on Growth of Escherichia coli. II. Comparison
of Results in Shake Flasks and 50-Liter Fermentor," L. E. McDaniel, E. G.
Bailey and A. Zimmerli, Appl. Microbiol.. 13, 115 (1965).
"High Pressure Oxygen as an Adjunct in Experimental Bacteremic Shock,"
R. Ollodart and E. Blair, J. Am. Med. Assoc.. 191, 736 (1965).
"Effect of Hyperbaric Oxygen on the Growth of Aerobic Organisms in Deep
Cultures," C. A. Pennock, Lancet.. 1, 1348 (1966).
"Inhibitory Effects of Hyperbaric Oxygen on Bacteria and Fungi," T. A.
McAllister, J. M. Stork, J. N. Norman, and R0 J. Ross, Lancet.. 2, 1040
(1963).
"Effect of Hyperbaric Oxygen on Aerobic Bacteria in^ vitro and in vivo."
D. Kaye, Proc. Soc. Exptl. Bio. Med.. 124,1090 (1967).
"Effects of Hyperbaric Oxygen on Some Common Pathogenic Bacteria," N. I.
Hopkinson and A. G. Towers, Lancet.. 2, 1361 (1963).
"The Effect of High-Pressure Oxygen on Chromogenic Bacteria," L. L. Reynolds
and J. W. King, Cleveland Clin. Quart.. 34, 171 (1967).
"Hyperbaric Oxygenation," S. F. Gottlieb, Advan. Clin. Chem.. 8, 69 (1965).
"Effect of Diet and Atmosphere on Intestinal and Skin Flora," Vol. I: Experi-
mental Data; Vol. II Literature Survey, P. E. Riely and L. S. Gall, NASA-CR-
661; 662.
"Effect of Diet and Atmosphere on Intestinal and Skin Flora," Summary Report,
L. S. Gall and P. E. Riely, NASA-CR-708. 211 (1967).
"Effects of Hyperbaric Oxygen on Some Common Pathogenic Bacteria," A. G.
Towers and W. I. Hopkinson, Aerospace Medicine. 36, 211 (1965).
"The General and Comparative Biology of Terrestrial Organisms Under Experi-
mental Stress Conditions," S. M. Siegel, NASA-CR-84032 (1966).
51
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General
"Use of Oxygen in Sludge Stabilization," J. H. Bruemmer, Purdue University,
Eng. Bull. Ext. Ser. No. 121, 544 (1966).
"Autoxidation of Wood Distillation Wastes with7 Oxygen," B. T. Riley, J. E.
Kiker and C. I. Harding, ibid., p. 926(1966).
52
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SELECTED WATER RESOURCES ABSTRACTS
INPUT TRANSACTION FORM
Organixutiitn
Midwest Research Institute
425 Volker Boulevard
Kansas City, Missouri 64110
Title
Oxygenation of Aqueous Bodies Using Liquid Oxygen-LOXination
10
Author(x)
Thomas D. Bath
William Garner
A, E. Vandegrift
16
Project Designation
Contract 14-12-168
21 Note
22
Citation
Contractor's Final Report
23
Descriptors (Starred First)
Oxygenaition^-y-Aeration*; Aerobic Treatment, Environmental Engineering,
Oxygen Demand, Oxygen Requirements, Pollution Abatement, Waste Assimilative
Capacity, Water Pollution '
25
Identifiers (Starred First) *
oA-^f^^^^7/
Liquid Oxygen*, LOXj^aMiori*,
Lcied.t-5—Stifption Efficiency"
97 Abstract
*•' I An experimental system was designed, constructed, and tested for the introduc«
tion of oxygen in the liquid state (LOX) into a body of water at 7° to 30°C. The sorption
of LOXS both by static water columns and by flowing water columns, was examined^ Sorption
efficiency and mass-transfer coefficients were calculated.
Under experimental conditions investigated, these coefficients did not appear
significantly different from those observed for gaseous oxygen. Water temperature, initial
dissolved-oxygen concentration, and shear at the point of oxygen injection were less signif-
icant in affecting the mass-transfer coefficients than was gross water turbulence. The mass-
transfer coefficients correlated with the corresponding Reynolds number.
Abstractor
William Garner
Institution
Midwest Research Institute
WR:I02 (REV. JUUY 1969)
WRSIC
SEND TO: WATER RESOURCES SCIENTIFIC INFORMATION CENTER
U.S. DEPARTMENT OF THE INTERIOR
WASHINGTON. D. C. 2O24O
* CPO: 1969-
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