U.S. patent number 3,842,270 [Application Number 05/410,850] was granted by the patent office on 1974-10-15 for pressurized oil-in-water monitor.
This patent grant is currently assigned to Continental Oil Company. Invention is credited to M. Duane Gregory, James E. Stolhand, Marvin E. Yost.
United States Patent |
3,842,270 |
Gregory , et al. |
October 15, 1974 |
PRESSURIZED OIL-IN-WATER MONITOR
Abstract
Method and apparatus for monitoring the presence in an aqueous
medium of an oil which fluoresces when irradiated by ultraviolet
light wherein the fluid stream being monitored does not come in
direct contact with the light source or detection means.
Inventors: |
Gregory; M. Duane (Ponca City,
OK), Stolhand; James E. (Ponca City, OK), Yost; Marvin
E. (Ponca City, OK) |
Assignee: |
Continental Oil Company (Ponca
City, OK)
|
Family
ID: |
23626494 |
Appl.
No.: |
05/410,850 |
Filed: |
October 29, 1973 |
Current U.S.
Class: |
250/301;
250/461.1; 250/365 |
Current CPC
Class: |
G01N
33/1833 (20130101); G01N 21/85 (20130101); G01N
21/64 (20130101); Y02A 20/206 (20180101); Y02A
20/20 (20180101) |
Current International
Class: |
G01N
33/18 (20060101); G01N 21/64 (20060101); G01n
021/34 () |
Field of
Search: |
;250/301,304,365,461 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Borchelt; Archie R.
Attorney, Agent or Firm: Floyd; Gerald L.
Claims
We claim:
1. An apparatus for monitoring in an aqueous base fluid an
oleaginous material which fluoresces when irradiated by ultraviolet
light comprising:
a. a vertically positioned tubular housing means for receiving a
stream of fluid to be monitored, said tubular housing means having
an upper portion having an internal diameter greater than the
diameter of the stream of fluid to provide an air annulus
therebetween, a bottom section of reduced diameter in which the
stream of fluid collects before passing out of the housing and a
first and second sealed transparent windows at the same horizontal
level in the upper portion of the lateral sidewall of the
housing,
b. means for introducing a stream of fluid into the upper portion
of said tubular housing means so that such fluid falls through said
upper portion without touching the lateral sidewall thereof,
c. means for introducing a beam of ultraviolet light through one of
the same sealed windows and into the falling stream of fluid,
d. means for detecting fluorescence radiation mounted outside said
tubular housing means opposite the other of the said sealed
windows,
e. a supply of gas at a pressure above the pressure in the tubular
housing connected to the upper portion of the tubular housing.
2. An apparatus for monitoring in an aqueous base fluid an
oleaginous material which fluoresces when irradiated by ultraviolet
light comprising:
a. a vertically positioned tubular housing means for receiving a
stream of fluid to be monitored, said tubular housing means having
an upper portion having an internal diameter greater than the
diameter of the stream of fluidid to provide an air annulus
therebetween, a bottom section of reduced diameter in which the
stream of fluid collects before passing out of the housing and a
first and second sealed transparent windows at the same horizontal
level in the upper portion of the lateral sidewall of the
housing,
b. means for introducing a stream of fluid into the upper portion
of said tubular housing means so that such fluid falls through said
upper portion without touching the lateral sidewall thereof,
c. means for introducing a beam of ultraviolet light through one of
the said sealed windows and into the falling stream of fluid,
d. means for detecting fluorescence radiation mounted outside said
tubular housing means opposite the other of the said sealed
windows,
e. means for detecting the height of the column of fluid which
collects in the bottom section of said tubular housing, and
f. means for injecting a gas into the air annulus in said tubular
housing when said height detecting means indicates that the height
of said column of fluid is approaching the level of said
windows.
3. The apparatus of claim 2 wherein the means for detecting the
height of the column of fluid which collects in the bottom section
of said tubular housing comprises two conductance probes mounted
through the lateral sidewall of said tubular housing vertically
spaced apart between the bottom section of said tubular housing and
the said windows.
4. The apparatus of claim 2 wherein the means for detecting the
height of the column of fluid which collects in the bottom section
of said tubular housing comprises a sight gauge mounted in the
lateral sidewall of said tubular housing between the bottom section
of said tubular housing and the said windows.
5. The apparatus of claim 2 wherein the means for detecting the
height of the column of fluid which collects in the bottom section
of said tubular goods controls a solenoid valve which admits gas
into the air annulus in said tubular housing.
6. The apparatus of claim 2 wherein the means for introducing a
stream of fluid into the upper portion of said tubular housing
means includes a flow controller to regulate the rate at which the
stream of fluid falls through the tubular housing.
7. The apparatus of claim 2 wherein the first and second sealed
windows are mounted at a right angle to each other in the tubular
housing.
8. The apparatus of claim 2 wherein the means for detecting
fluorescence radiation of (d) comprises a photocell positioned
behind a filter which filters out incident ultraviolet light.
9. The apparatus of claim 2 wherein the tubular housing is provided
with splash guards positioned between the lateral sidewall of the
tubular housing and the falling stream of fluid which splash guards
decrease splashing of the fluid onto the sealed transparent
windows.
10. The apparatus of claim 2 wherein the fluorescence radiation
detecting means of (d) is supplied with a constant temperature
jacket maintained at the same temperature as the fluid stream.
11. A method for monitoring in an aqueous base fluid an oleaginous
material which fluoresces when irradiated by ultraviolet light
comprising:
a. injecting a fluid to be monitored into the upper portion of a
vertically positioned tubular housing so that a stream of said
fluid falls through the tubular housing without touching the
lateral sidewall of said upper portion of the tubular housing,
b. collecting said fluid in the bottom portion of said tubular
housing which bottom portion has a diameter which is smaller than
the diameter of the upper section thereof,
c. discharging said fluid from said tubular housing,
d. irradiating said falling stream of fluid with ultraviolet light
transmitted through a first transparent sealed window in the upper
portion of said tubular housing,
e. detecting fluorescence radiation from said irradiated falling
stream of fluid through a second transparent sealed window in the
upper portion of the housing, and
f. injecting a gas into the upper portion of said tubular housing
to suppress the height of the column of fluid collected in the
bottom portion of the tubular housing below the level of the
transparent sealed windows.
12. A method for monitoring in an aqueous base fluid an oleaginous
material which fluoresces when irradiated by ultraviolet light
comprising:
a. injecting a fluid to be monitored into the upper portion of a
vertically positioned tubular housing so that a stream of said
fluid falls through the tubular housing without touching the
lateral sidewall of said upper portion of the tubular housing,
b. collecting said fluid in the bottom portion of said tubular
housing which bottom portion has a diameter which is smaller than
the diameter of the upper section thereof,
c. discharging said fluid from said tubular housing,
d. irradiating said falling stream of fluid with ultraviolet light
transmitted through a first transparent sealed window in the upper
portion of said tubular housing,
e. detecting fluorescence radiation from said irradiated falling
stream of fluid through a second transparent sealed window in the
upper portion of the housing, and
f. detecting the height of the column of fluid collected in the
bottom of the tubular housing, and
g. injecting a gas into the upper portion of said tubular housing
when the height detection of (f) indicates that the height of said
fluid column is approaching the level of the sealed transparent
windows.
13. The method of claim 12 wherein the gas injection of (g) is
maintained at a rate so that the pressure in the tubular housing is
at least 10 pounds per square inch greater than the pressure of the
discharged fluid of (e).
Description
BACKGROUND OF THE INVENTION
a. Field of the Invention
The present invention relates to a method and apparatus for
moniotring the presence in an aqueous medium of a material which
fluoresces when exposed to ultraviolet light. More particularly, it
relates to such a method and apparatus which operate under
pressurized conditions.
B. Description of the Prior Art
Various aqueous base liquid streams which are handled in industrial
processes also contain minor proportions of oleaginous base
materials. It is oftentimes desirable to determine the presence of
and concentration of such oleaginous base materials. Many
oleaginous base materials fluoresce when exposed to ultraviolet
light, emitting visible light. Thus, detection methods and
apparatus have developed wherein a beam of ultraviolet light is
cast on a liquid stream and the amount of visible light emitted, if
any, detected. In one type of apparatus, the liquid stream is
passed through a glass cell with the ultraviolet light beam and the
emitted visible light passing through the glass. However, in such
an apparatus, the liquid continually contacts the glass and the
oleaginous materials tend to gradually coat the glass surface
causing the apparatus to give a falsely high reading for the
oleaginous materials. There also has been used a similar apparatus
employing light detection in which the stream of liquid being
monitored does not touch the ultraviolet light source or visible
light detection means. Such an apparatus is described in U.S. Pat.
No. 3,581,085 issued May 25, 1971, to Barrett. In this apparatus,
the liquid stream to be monitored falls down a tube without
touching the sides of the tube, collects in the bottom of the tube
and is discharged. The space between the falling liquid stream and
the sides of the tube is occupied by air. The ultraviolet light
source and visible light detection means are mounted outside the
tube opposite holes in the tube. This apparatus functions during
its initial phase of operation without any coating of the light
source or detection means by the liquid being monitored. However,
it has been found that the falling stream of liquid tends to
entrain and dissolve some of the air occupying the space between
the stream of liquid and the sides of the tube, carries this air to
the bottom of the tube and on out of the tube. Thus, as operation
of the apparatus proceeds, the amount of air in the tube steadily
decreases. The height of the pool of liquid collecting in the
bottom of the tube rises to fill the space formerly occupied by the
air until liquid reaches the level of the light source and
detecting means, contaminates the same with oleaginous material and
renders further monitoring possible.
It is an object of this invention to provide a method and apparatus
for monitoring the presence of an oleaginous fluorescing material
in an aqueous liquid.
It is a further object to provide such a method and apparatus which
provide continuous monitoring on a stream of such liquid.
It is a still further object to provide an apparatus for such
monitoring utilizing a light source and detection means wherein the
liquid to be monitored initially does not directly contact the
light source detection means.
It is another object to provide means for keeping the liquid out of
direct contact with the light source and detection means throughout
the operation of the apparatus.
Other objects, advantages, and features of the invention will
become apparent from the following specification and appended
claims.
BRIEF SUMMARY OF THE INVENTION
This invention involves a method and apparatus for continually
monitoring an oleaginous material which fluoresces when exposed to
ultraviolet light, which oleaginous material is present in an
aqueous base liquid comprising:
a. a tubular housing through which falls a stream of liquid to be
monitored, such housing having an internal diameter greater than
the diameter of the falling stream of liquid to provide an air
annulus therebetween, a bottom section of reduced diameter in which
the stream of liquid collects before passing out of the housing and
two sealed windows at the same horizontal level in the upper
portion of the lateral sidewall of the housing,
b. means for introducing a stream of liquid into the upper portion
of the housing so that such liquid falls through the housing
without touching the lateral sidewalls thereof,
c. means for introducing a beam of ultraviolet light through one of
the windows in the housing and into the falling stream of
liquid,
d. means for detecting fluorescence radiation mounted outside the
housing opposite the other window in the housing,
e. means for detecting the height of the column of liquid which
collects in the bottom portion of the housing, and
f. means for injecting a gas into the air annulus in the housing
before the height of the column of liquid which collects in the
bottom portion of the housing reaches the level of the windows in
the lateral sidewalls of the housing.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a cross sectional schematic view of the apparatus of this
invention.
FIG. 2 is a cross sectional schematic view of the main body of the
subject apparatus of FIG. 1 taken along the Plane 2--2 of FIG.
1.
FIG. 3 is a cross sectional schematic view of an alternate
embodiment of the fluid level control means.
FIG. 4 is a graph illustrating the calibration of the apparatus of
this invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring to FIGS. 1 and 2, the apparatus, generally denoted by
Reference 10, comprises means for supplying a stream of fluid to be
monitored such as Valve 12 through which the composition to be
monitored enters and preferably passes through inlet tube 14. The
main body of the composition passes through flow controller 16 and
tubing 18 into rotameter 20 which measures the rate of flow.
From rotameter 20, the main body of composition passes through
tubing 22 into the top of housing 24. The composition then falls
through housing 24 as stream 26 collects in the bottom of housing
24 and forms fluid column 28. The composition drains from the
bottom of housing 24 and is withdrawn from the apparatus via tubing
30, valve 32, tubing 34, and valve 36. It is preferred that a small
portion of the composition be withdrawn from tubing 14 via tubing
38 and valve 40, passed through constant temperature jacket 42 and
then through tubing 44 which discharges into tubing 34.
Housing 24 is conveniently made in upper section 46 and lower
section 48 connected by flange 50 and sealing mecnanism 52 such as
an O-ring. Housing 24 is provided with first aperture 54, covered
by transparent window 56 which may be made of quartz, glass or
other solid transparent to light. Sealing mechanism 58, such as an
O-ring, is provided between housing 24 and transparent window 56.
Transparent window 56 is held in position by locking mechanism 59,
such as a locking nut. A source of ultraviolet radiation 60 is
positioned outside housing 24 and located so as to pass a beam of
ultraviolet radiation through the transparent window 56 and through
composition stream 26.
Housing 24 is also provided with second aperture 62 positioned at
the same height as first aperture 54 and at any position around the
circumference of housing 24, preferably at right angles to first
aperture 54.
This universal positioning of aperture 62 with respect to aperture
54 is made possible by a filter 110 in the photocell detector 70
that keeps the incident ultraviolet light from activating the
photocell. The only light that may enter the photocell detector 70
is long wavelength fluorescent light the intensity of which is
proportional to the contaminant concentration in the stream to be
monitored. Thus, photocell detector 70 detects the fluorescence
radiation created by ultraviolet light striking composition stream
26. This is generally visible light.
Second aperture 62 is covered by transparent window 64. Sealing
mechanism 66, such as an O-ring, is provided between housing 24 and
transparent window 64. Transparent window 64 is held in position by
locking mechanism 68, such a locking nut. Visible light detecting
means 70, such as a photocell, is positioned outside housing 24
behind transparent window 64. Visible violet light detecting means
70 is surrounded by constant temperature jacket 42 which decreases
fogging of transparent window 64 which can occur during operation
of the apparatus in the absence of constant temperature jacket 42.
The fluorescent light transmitted from stream 26 is picked up by
visible light detecting means 70 and the results observed visually
or recorded on a suitable recording means, such as wires 72 which
connect visible light detecting means 70 to amplifier 74 which in
turn is electrically connected by wires 76 to recorder 78.
It is preferred that housing 24 be provided with splash guard means
80 and 82 positioned between the lateral sidewall of housing 24 and
stream 26. Upper splash guard means 80 is preferably a hollow
cylinder attached to the top of housing 24 and provides a shroud
around the upper portion of stream 26. The bottom of upper splash
guard 80 is just above apertures 54 and 62. Lower splash guard 82
is preferably a hollow cylinder attached to the lateral sidewall of
housing 24 at a point below apertures 54 and 62. The top of lower
splash guard 82 extends to just below apertures 54 and 62. The
function of splash guards 80 and 82 is to reduce the amount of
liquid from stream 26 and fluid column 28 that splashes onto
transparent windows 56 and 64 during operation of the
apparatus.
It was experienced during operation of the apparatus as described
above that falling stream 26 dissolved and entrained a portion of
the air in the housing and carried this air with it into fluid
column 28 and then on out of housing 24. Thus, as the quantity of
air in housing 24 decreased, the height of fluid column 28 would
gradually rise in housing 24 until it reached the level of
transparent windows 56 and 64 and cover the same, thus disrupting
the desired observations. To prevent housing 24 from filling with
liquid in this manner, it is necessary to inject gas into housing
24. This can be done by constantly bleeding gas from gas supply 84
which is at a pressure above the pressure in housing 24 into
housing 24 via tubing 86 and control valve 88. Preferably gas is
intermittently injected into housing 24 before the height of fluid
column 28 gets dangerously close to transparent windows 56 and 64.
The intermittent injection can be achieved by a means for detecting
the height of fluid column 28 in housing 24 which controls means
for injecting gas into housing 24. The means for detecting the
height of fluid column 28 in housing 24 can be lower level
conductance probe 90 and upper level conductance probe 92. These
level probes extend through the side of housing 24. Lower level
probe 90 is positioned near the bottom of housing 24. Upper level
probe 92 is vertically positioned therefrom at a point below
transparent windows 56 and 64. Lower level probe 90 and upper level
probe 92 are electrically connected by wire 94 to level controller
96. Level controller 96 is electrically connected by wire 98 to
solenoid valve 88 which controls flow of gas from gas supply 84
into housing 24. Pressure gauge 100 indicates the pressure in the
housing. The pressure inside housing 24 should be maintained about
10 psi above the pressure downstream of monitor 10. When the height
of fluid column 28 rises in housing 24 and touches upper level
probe 92, level controller 96 opens solenoid valve 88 allowing gas
to flow into housing 24, thus depressing the height of fluid column
28. When the height of fluid column 28 falls in housing 24 below
lower level probe 90, level controller 96 closes solenoid valve
stopping flow of gas into housing 24.
An alternate means for detecing the height of fluid column 28 in
housing 24 comprises a sight gauge means such as shown in FIG. 3
wherein hollow sight gauge column 102 connected to the interior of
housing 24 at its upper and lower end is provided with lower light
source and photocell combination 104, upper light source and
photocell combination 106 and opaque ball 108 which floats on fluid
column 28 extending into the sight gauge means. Lower light source
and photocell combination 104 and upper light source and photocell
combination 106 are electrically connected by wire 94 to flow
controller 96. When the height of fluid column 28 rises so that
opaque ball 108 interrupts light between upper light source and
photocell combination 106, level controller 96 opens solenoid valve
88 allowing gas to flow into housing 24. When the height of fluid
in column 28 falls so that opaque ball 108 interrupts light between
lower light source and photocell combination 104, level controller
96 closes solenoid valve 88 stopping flow of gas into housing
24.
The apparatus of this invention can be used to monitor the presence
in an aqueous medium of small concentrations of an oleaginous
material which fluoresces when irradiated by ultraviolet light (220
to 350 nanometers. The oleaginous material may be a petroleum oil
such as crude oil or any fraction or refined product thereof. The
compounds most responsible for fluorescence in oil are the
polynuclear aromatics. The fluorescent yield of an oil depends both
upon the polynuclear aromatic content and upon the kinds of
molecules comprising the polynuclear aromatics. The size of oil
particles injected into the optical path has an effect on
fluorescent intensity. Above 5 microns variation in particle
diameter will result in fluctuations of the output signal due to
surface effects. Below 5 microns in diameter, particles become
essentially transparent and fluorescence becomes independent of
particle size. If the fluid to be monitored contains oil particles
having a diameter of more than 5 microns, it is preferred to pass
the fluid through a high shear pump positioned upstream of the
monitor to create smaller dispersed oil droplets with a narrower
drop size distribution.
The gas injected into the housing to supress the column of liquid
in the housing can be any gas which is inert to the falling stream
of liquid. Suitable gases include air, oxygen, carbon dioxide,
combustion gases, nitrogen, argon, and similar inert gases. The
aqueous base fluid may be water or any brine.
EXAMPLE
An apparatus was assembled as described above using 1/2-inch
diameter tubing 22 to introduce the fluid stream into housing 24 at
the rate of 1 gallon per minute. The pressure in housing 24 was
regulated by ball valve 32 to a pressure 10 pounds per square inch
above the system into which the fluid is being discharged through
valve 36. Conductance probes 90 and 92 were insulated from the
metal of housing 24 by drilled-out fittings of nylon, a
non-conductor. Conductor probes 90 and 92 were coated by a thin
coating of epoxy resin, a non-conductor, except for one-half inch
on each end. Probes 90 and 92 were O-ring sealed in the nylon
fittings. As the signal from the photocell is sometimes weak if the
concentration in the aqueous medium of materials which fluoresce is
small, it is preferred to use an amplifier. In these tests,
three-decade amplifier 74 which contained a potentiometer for
setting the zero point recorder 78 was used. 1,000-ohm single
channel micro-ampere recorder 78 was used with a recorder chart
speed of one inch per hour to give a one-month life expectancy to
each roll of chart paper. The mercury lamp ultraviolet light source
exhibits its greatest intensity at 254 nm with less intense
spectral lines occurring up to 577 nm. To initiate fluorescence in
a molecule, the exciting wavelength must be within a certain energy
range characteristic of the molecule. Most dark crude oils
fluoresce most intensely when excited with energy in the 300 to 400
nm range. Thus, the spectrum of the mercury lamp was altered by
using two filters. One filter was used to shift the 254 nm peak to
366 nm. A band pass filter was used to limit the emiitted light to
the 300 to 400 nm range.
The monitor was calibrated by passing a series of streams of fluid
of varying oil concentration through the monitor and plotting the
results of the recorder reading for each versus oil concentration
as determined by some standard analytical technique. The monitor
was installed on a water line entering a waterflood injection tank.
The water was water which had been produced from an oil producing
well, separated as nearly as possible from the oil and was being
injected into a subterranean formation via another well to serve as
a drive fluid in an effort to recover additional oil from the
formation. The "water" contained some oil which had not been
completely separated therefrom. Readings were obtained with
amplifier set on 1 and 2. When fluctuations in the readings were
observed, samples of the water passing through the monitor were
obtained and the oil concentration thereof determined using a
standard colorimetric method of analysis. FIG. 4 shows a plot of
recorder readings versus oil concentrations obtained in the
colorimetric analysis. For an amplifier setting of 2, the slope of
the calibration curve was very nearly unity showing that each part
per million of oil caused recorder response of 1 microamp. When the
type of oil in the fluid being monitored changes, the monitor must
be recalibrated.
Even though the foregoing discussion has described certain specific
embodiments of this invention, it is to be understood that numerous
other arrangements will be obvious to those skilled in the art
which embody the principles of the invention and fall within the
scope thereof.
* * * * *