U.S. patent application number 16/248469 was filed with the patent office on 2020-07-16 for non-destructive gas concentration analyzer.
This patent application is currently assigned to Enos Analytical, LLC. The applicant listed for this patent is Enos Analytical, LLC. Invention is credited to Quan Shi, Allan S. Tseng.
Application Number | 20200225149 16/248469 |
Document ID | / |
Family ID | 69529047 |
Filed Date | 2020-07-16 |
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United States Patent
Application |
20200225149 |
Kind Code |
A1 |
Shi; Quan ; et al. |
July 16, 2020 |
NON-DESTRUCTIVE GAS CONCENTRATION ANALYZER
Abstract
A gas analyzer to non-destructively detect the concentration of
a gas in a container includes a sensor unit with an infrared
emitter configured to transmit infrared radiation over a path
through the container. There is an infrared detector configured to
receive a portion of the infrared radiation transmitted by the
infrared emitter and to produce an output signal corresponding to
the received radiation. There is a processor module, in
communication with the sensor unit, configured to receive the
detected spectrum from the infrared detector, the detected spectrum
including a trough region at wavelengths which absorb the gas in
the pressurized container. The processor is also configured to form
an interpolated baseline spectrum from the detected spectrum by
interpolating baseline data points spanning the trough region and
to calculate a gas concentration in the container using the
detected spectrum and the interpolated baseline spectrum.
Inventors: |
Shi; Quan; (West Roxbury,
MA) ; Tseng; Allan S.; (Chelmsford, MA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Enos Analytical, LLC |
Acton |
MA |
US |
|
|
Assignee: |
Enos Analytical, LLC
Acton
MA
|
Family ID: |
69529047 |
Appl. No.: |
16/248469 |
Filed: |
January 15, 2019 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G01N 21/359 20130101;
G01N 21/3504 20130101; G01K 13/00 20130101; G01N 33/14 20130101;
G01N 2021/3513 20130101 |
International
Class: |
G01N 21/3504 20060101
G01N021/3504; G01N 21/359 20060101 G01N021/359; G01K 13/00 20060101
G01K013/00 |
Claims
1. A gas analyzer to non-destructively determine the concentration
of a gas in a pressurized transparent or semitransparent container
having a neck portion extending from a shoulder and terminating in
an opening, the opening being sealed with a cap, comprising: a
sensor unit including: a first surface, a second surface, opposite
the first surface, and a sensor region between the first and second
surfaces, the sensor region including a first end having a stop
surface and the second end including an aperture, in communication
with the sensor region, configured to receive a neck portion of a
container in the sensor region until a cap contacts the stop
surface; the sensor unit further includes at least one sidewall
extending from the first surface toward the second surface; an
infrared emitter affixed to the at least one sidewall and
configured to transmit infrared radiation across the sensor region;
and an infrared detector affixed to the at least one sidewall,
opposite the infrared emitter, and configured to receive infrared
radiation transmitted by the infrared emitter across the sensor
region and to provide an output signal corresponding to the
received infrared radiation; wherein the infrared emitter and the
infrared detector are each affixed to the at least one sidewall,
spaced a distance, d, from the stop surface in the direction of the
aperture, wherein the distance, d, corresponds to a predetermined
distance from the cap to a location on the neck portion of the
container; and a processor module, in communication with the sensor
unit, configured to receive the output signal from the infrared
detector and to determine a concentration of the gas in the
container.
2. The gas analyzer of claim 1 wherein the infrared radiation
comprises near infrared radiation.
3. The gas analyzer of claim 1 wherein the sensor unit includes
four sidewalls, and wherein the infrared transmitted is affixed to
a first sidewall and the infrared detector is affixed to a second
sidewall opposite the first sidewall.
4. The gas analyzer of claim 1 wherein spacing the infrared
transmitter and the infrared detector the distance, d, from the
stop surface in the direction of the aperture, which corresponds to
a predetermined distance from the cap to a location on the neck
portion of the container, provides a fixed transmission path length
across the neck portion of the container
5. The gas analyzer of claim 1 wherein the processor module is
separate from the sensor unit.
6. The gas analyzer of claim 1 wherein the processor module
includes a display device configured to display the concentration
of the gas determined to be in the container.
7. The gas analyzer of claim 1 wherein the container is partially
filled with a liquid and the interior region of the container above
the liquid constitutes a headspace, and wherein the distance d from
the cap to a location on the neck portion of the container is
positioned within the headspace.
8. The gas analyzer of claim 7 further including a temperature
sensor in communication with the sensor region and wherein the
processor module uses the output signal to determine a gas
concentration in the headspace, and from the gas concentration in
the head space and a temperature measured in the sensor region by
the temperature sensor, the processor module determines a gas
concentration in the liquid.
9. A gas analyzer to non-destructively detect the concentration of
a gas in a pressurized transparent or semi-transparent container,
comprising: a sensor unit including; an infrared emitter configured
to be positioned on a first side of a pressurized container and to
transmit infrared radiation over a path through the pressurized
container; wherein the infrared radiation has an infrared spectrum
including wavelengths which absorb a gas in the pressurized
container and wavelengths which do not absorb the gas in the
pressurized container; an infrared detector configured to be
positioned on a second side of the pressurized container, opposite
the first side, and configured to receive a portion of the infrared
radiation transmitted by the infrared emitter over the path through
the pressurized container and to produce detected spectrum
corresponding to the received radiation; and a processor module, in
communication with the sensor unit, configured to: receive the
detected spectrum from infrared detector, the detected spectrum
including a trough region at wavelengths which absorb the gas in
the pressurized container; form an interpolated baseline spectrum
from the detected spectrum by interpolating baseline data points
spanning the trough region; and calculate a gas concentration in
the pressurized container using the detected spectrum and the
interpolated baseline spectrum.
10. The gas analyzer of claim 9 wherein the infrared radiation
comprises near infrared radiation.
11. The gas analyzer of claim 9 wherein the sensor unit includes a
first surface, a second surface, opposite the first surface, and a
sensor region between the first and second surfaces, the sensor
region within the sensor unit including a first end having a stop
surface and the second end including an aperture, in communication
with the sensor region, and configured to receive a neck portion of
a container in the sensor region until a cap contacts the stop
surface; the sensor unit further includes at least one sidewall
extending from the first surface toward the second surface
12. The gas analyzer of claim 9 wherein the sensor unit includes
four sidewalls, and wherein the infrared transmitted is affixed to
a first sidewall and the infrared detector is affixed to a second
sidewall opposite the first sidewall.
13. The gas analyzer of claim 11 wherein the infrared emitter and
the infrared detector are each affixed to the at least one
sidewall, spaced a distance, d, from the stop surface in the
direction of the aperture, wherein the distance, d, corresponds to
a predetermined distance from the cap to a location on the neck
portion of the container
14. The gas analyzer of claim 13 wherein spacing the infrared
transmitter and the infrared detector the distance, d, from the
stop surface in the direction of the aperture, which corresponds to
a predetermined distance from the cap to a location on the neck
portion of the container, provides a fixed transmission path length
across the neck portion of the container
15. The gas analyzer of claim 9 wherein the processor module is
separate from the sensor unit.
16. The gas analyzer of claim 9 wherein the processor module
includes a display device configured to display the concentration
of the gas determined to be in the container.
17. The gas analyzer of claim 14 wherein the container is partially
filled with a liquid and the interior region of the container above
the liquid constitutes a headspace, and wherein the distance d from
the cap to a location on the neck portion of the container is
positioned within the headspace.
18. The gas analyzer of claim 17 further including a temperature
sensor in communication with the sensor region and wherein the
processor module uses the output signal to determine a gas
concentration in the headspace, and from the gas concentration in
the head space and a temperature measured in the sensor region by
the temperature sensor, the processor module determines a gas
concentration in the liquid.
19. The gas analyzer of claim 18 wherein the processor module is
further configured to use a plurality of data points on each side
of the trough to perform a non-linear curve fitting to obtain the
baseline data points spanning the trough region.
20. The gas analyzer of claim 19 wherein the processor module is
further configured to divide the detected spectrum by the
interpolated baseline spectrum to produce a normalized spectrum
indicative of the energy received by infrared detector.
21. The gas analyzer of claim 20 wherein the processor module is
further configured to determine an absorbance of energy due to the
gas using the normalized spectrum.
22. The gas analyzer of claim 21 wherein the processor module is
further configured to, using the absorbance of energy, calculate a
concentration of the gas in the headspace of the container.
23. The gas analyzer of claim 22 wherein the processor module is
further configured to, using the concentration of the gas in the
headspace and the temperature in the sensor region, determine a
concentration of the gas dissolved in the liquid.
24. A method to non-destructively detect the concentration of a gas
in a pressurized transparent or semi-transparent container, the
method comprising: transmitting, using an infrared emitter
positioned on a first side of a pressurized container, infrared
radiation over a path through the pressurized container; wherein
the infrared radiation has an infrared spectrum including
wavelengths which absorb a gas in the pressurized container and
wavelengths which do not absorb the gas in the pressurized
container; receiving, using an infrared detector positioned on a
second side of the pressurized container, opposite the first side,
a portion of the infrared radiation transmitted by the infrared
emitter over the path through the pressurized container and to
produce detected spectrum corresponding to the received radiation;
receiving the detected spectrum from infrared detector, the
detected spectrum including a trough region at wavelengths which
absorb the gas in the pressurized container; forming an
interpolated baseline spectrum from the detected spectrum by
interpolating baseline data points spanning the trough region; and
calculating a gas concentration in the pressurized container using
the detected spectrum and the interpolated baseline spectrum.
25. The method of claim 24 wherein the infrared radiation comprises
near infrared radiation.
26. The method of claim 24 wherein the infrared transmitter and the
infrared detector are spaced a predetermined distance from a cap of
the container to a location on the neck portion of the container to
provide a fixed transmission path length across the neck portion of
the container.
27. The method of claim 24 including displaying the concentration
of the gas determined to be in the container.
28. The method of claim 26 wherein the container is partially
filled with a liquid and the interior region of the container above
the liquid constitutes a headspace, and wherein the fixed
transmission path length is positioned within the headspace.
29. The method of claim 28 further including determining a
temperature proximate the container, using the detected spectrum to
determine a gas concentration in the headspace, and, from the gas
concentration in the head space and temperature proximate the
container, determining a gas concentration in the liquid.
30. The method of claim 29 further including using a plurality of
data points on each side of the trough to perform a non-linear
curve fitting to obtain the baseline data points spanning the
trough region.
31. The method of claim 30 further including dividing the detected
spectrum by the interpolated baseline spectrum to produce a
normalized spectrum indicative of the energy received by infrared
detector.
32. The method of claim 31 further including determining an
absorbance of energy due to the gas using the normalized
spectrum.
33. The method of claim 32 further including, using the absorbance
of energy, calculating a concentration of the gas in the headspace
of the container.
34. The method of claim 33 further including, using the
concentration of the gas in the headspace and the temperature in
the sensor region, determining a concentration of the gas dissolved
in the liquid.
Description
FIELD OF THE INVENTION
[0001] This invention relates to a non-destructive gas
concentration analyzer and more specifically to a non-destructive
gas concentration analyzer which may more rapidly determine gas
concentration in a variety of transparent or semi-transparent
containers filled with a solution sealed under pressure.
BACKGROUND OF THE INVENTION
[0002] Plastic materials are often used as containers for beverages
and, for carbonated beverages, the plastic material forms a barrier
against permeation of the gas, e.g. carbon dioxide, which provides
the carbonation. A reduction of the carbon dioxide permeation rate
helps to maintain a high level of carbonation in the carbonated
beverages. Therefore, the choice of suitable plastic material, the
distribution of the material, and the processing conditions are
important factors in producing such plastic containers. One major
difficulty with volume production of plastic containers is that
periodic sampling of production containers is required to ensure
that the container is performing to the desired specifications and
containing carbon dioxide as desired.
[0003] Originally, the periodic sampling of plastic containers
required actual, direct measurement of the carbon dioxide in the
container. This was complex and required large test equipment,
including plumbing and precision gas detectors, to destructively
test the plastic containers. In addition, since the decrease over
time in carbonation level in a sealed container may be slight, a
test cycle would usually last for several weeks before an estimate
of carbonation loss rate could be obtained for predicting the shelf
life of a carbonated beverage.
[0004] Non-destructive carbon dioxide testing systems, which allow
for more rapid testing of plastic containers during production,
have been developed. One such system is described in U.S. Pat. No.
5,614,718, which requires the creation of a prediction model using
one or more analysis containers. The analysis containers are
subjected to spectral analysis using near infrared (NIR)
transmission to acquire spectral signatures from the one or more
containers. The containers are also physically measured to obtain
the dimensions which are then stored as calibration data. From the
spectral analysis and the calibration data, prediction models are
created and then used to non-invasively test production containers
filled with carbonated beverages to predict carbonation retention
and shelf-life. The non-invasive testing of production containers
involves transmitting NIR energy through the production container
and measuring the received NIR energy. Using the received energy
and the prediction model, carbonation retention may be
determined.
[0005] This non-destructive test system reduces carbon dioxide
retention test times from several weeks, as described above with
the destructive testing, to minutes or less. However, a new
prediction model is required for each new container type to be
tested. Moreover, this system is suitable for use in a carbonated
beverage facility and not for field testing carbonation levels of
carbonated beverages on the shelf in stores or in inventory.
[0006] Therefore, there is a need for a smaller and simpler
non-destructive carbonation concentration analyzer which may more
rapidly test for carbon dioxide concentration in the field in a
variety of transparent or semi-transparent containers without the
need for predetermined prediction models, such as described in U.S.
Pat. No. 5,614,718.
BRIEF SUMMARY OF THE INVENTION
[0007] The benefits and advantages of the present invention over
existing systems will be readily apparent from the Brief Summary of
the Invention and Detailed Description to follow. One skilled in
the art will appreciate that the present teachings can be practiced
with embodiments other than those summarized or disclosed
below.
[0008] In one aspect the invention features a gas analyzer to
non-destructively determine the concentration of a gas in a
pressurized transparent or semitransparent container having a neck
portion extending from a shoulder and terminating in an opening,
the opening being sealed with a cap. There is a sensor unit
including a first surface, a second surface, opposite the first
surface, and a sensor region between the first and second surfaces.
The sensor region includes a first end having a stop surface and
the second end including an aperture, in communication with the
sensor region, configured to receive a neck portion of a container
in the sensor region until a cap contacts the stop surface. The
sensor unit further includes at least one sidewall extending from
the first surface toward the second surface and an infrared emitter
affixed to the at least one sidewall and configured to transmit
infrared radiation across the sensor region. There is an infrared
detector affixed to the at least one sidewall, opposite the
infrared emitter, and configured to receive infrared radiation
transmitted by the infrared emitter across the sensor region and to
provide an output signal corresponding to the received infrared
radiation. The infrared emitter and the infrared detector are each
affixed to the at least one sidewall, spaced a distance, d, from
the stop surface in the direction of the aperture, wherein the
distance, d, corresponds to a predetermined distance from the cap
to a location on the neck portion of the container. There is a
processor module, in communication with the sensor unit, configured
to receive the output signal from the infrared detector and to
determine a concentration of the gas in the container.
[0009] In other aspects of the invention one or more of the
following features may be included. The infrared radiation may
comprise near infrared radiation. The sensor unit may include four
sidewalls, and the infrared transmitted may be affixed to a first
sidewall and the infrared detector is affixed to a second sidewall
opposite the first sidewall. Spacing the infrared transmitter and
the infrared detector the distance, d, from the stop surface in the
direction of the aperture, which corresponds to a predetermined
distance from the cap to a location on the neck portion of the
container, may provide a fixed transmission path length across the
neck portion of the container. The processor module may be separate
from the sensor unit and it may include a display device configured
to display the concentration of the gas determined to be in the
container. The container may be partially filled with a liquid and
the interior region of the container above the liquid constitutes a
headspace, and the distance d from the cap to a location on the
neck portion of the container may be positioned within the
headspace. There may also be included a temperature sensor in
communication with the sensor region and the processor module may
use the output signal to determine a gas concentration in the
headspace, and from the gas concentration in the head space and a
temperature measured in the sensor region by the temperature
sensor, the processor module may determine a gas concentration in
the liquid.
[0010] In another aspect, the invention features a gas analyzer to
non-destructively detect the concentration of a gas in a
pressurized transparent or semi-transparent container. There is a
sensor unit including an infrared emitter configured to be
positioned on a first side of a pressurized container and to
transmit infrared radiation over a path through the pressurized
container. The infrared radiation has an infrared spectrum
including wavelengths which absorb a gas in the pressurized
container and wavelengths which do not absorb the gas in the
pressurized container. There is an infrared detector configured to
be positioned on a second side of the pressurized container,
opposite the first side, and configured to receive a portion of the
infrared radiation transmitted by the infrared emitter over the
path through the pressurized container and to produce detected
spectrum corresponding to the received radiation. There is also a
processor module, in communication with the sensor unit, configured
to receive the detected spectrum from infrared detector. The
detected spectrum includes a trough region at wavelengths which
absorb the gas in the pressurized container. The processor is also
configured to form an interpolated baseline spectrum from the
detected spectrum by interpolating baseline data points spanning
the trough region and it is configured to calculate a gas
concentration in the pressurized container using the detected
spectrum and the interpolated baseline spectrum.
[0011] In further aspects of the invention one or more of the
following features may be included. The infrared radiation may
comprise near infrared radiation. The sensor unit may include a
first surface, a second surface, opposite the first surface, and a
sensor region between the first and second surfaces. The sensor
region may be within the sensor unit and include a first end having
a stop surface and the second end may include an aperture, in
communication with the sensor region. The aperture may be
configured to receive a neck portion of a container in the sensor
region until a cap contacts the stop surface. The sensor unit may
further include at least one sidewall extending from the first
surface toward the second surface. The sensor unit may include four
sidewalls, and the infrared transmitted may be affixed to a first
sidewall and the infrared detector may be affixed to a second
sidewall opposite the first sidewall. The infrared emitter and the
infrared detector may each be affixed to the at least one sidewall,
spaced a distance, d, from the stop surface in the direction of the
aperture, wherein the distance, d, corresponds to a predetermined
distance from the cap to a location on the neck portion of the
container. Spacing the infrared transmitter and the infrared
detector the distance, d, from the stop surface in the direction of
the aperture, which corresponds to a predetermined distance from
the cap to a location on the neck portion of the container, may
provide a fixed transmission path length across the neck portion of
the container.
[0012] In yet further aspects of the invention one or more of the
following features may be included. The processor module may be
separate from the sensor unit and it may include a display device
configured to display the concentration of the gas determined to be
in the container. The container may be partially filled with a
liquid and the interior region of the container above the liquid
constitutes a headspace, and the distance d from the cap to a
location on the neck portion of the container may be positioned
within the headspace. There may further be a temperature sensor in
communication with the sensor region and the processor module may
use the output signal to determine a gas concentration in the
headspace. From the gas concentration in the head space and a
temperature measured in the sensor region by the temperature
sensor, the processor module may determine a gas concentration in
the liquid. The processor module may further be configured to use a
plurality of data points on each side of the trough to perform a
non-linear curve fitting to obtain the baseline data points
spanning the trough region. The processor module may further be
configured to divide the detected spectrum by the interpolated
baseline spectrum to produce a normalized spectrum indicative of
the energy received by infrared detector. The processor module may
also be configured to determine an absorbance of energy due to the
gas using the normalized spectrum and, using the absorbance of
energy, calculate a concentration of the gas in the headspace of
the container. The processor module may be configured to, using the
concentration of the gas in the headspace and the temperature in
the sensor region, determine a concentration of the gas dissolved
in the liquid.
[0013] In another aspect, the invention features a method to
non-destructively detect the concentration of a gas in a
pressurized transparent or semi-transparent container. The method
includes transmitting, using an infrared emitter positioned on a
first side of a pressurized container, infrared radiation over a
path through the pressurized container. The infrared radiation has
an infrared spectrum including wavelengths which absorb a gas in
the pressurized container and wavelengths which do not absorb the
gas in the pressurized container. The method also includes
receiving, using an infrared detector positioned on a second side
of the pressurized container, opposite the first side, a portion of
the infrared radiation transmitted by the infrared emitter over the
path through the pressurized container and to produce detected
spectrum corresponding to the received radiation. The method
additionally includes receiving the detected spectrum from infrared
detector, the detected spectrum including a trough region at
wavelengths which absorb the gas in the pressurized container and
forming an interpolated baseline spectrum from the detected
spectrum by interpolating baseline data points spanning the trough
region. The method then involves calculating a gas concentration in
the pressurized container using the detected spectrum and the
interpolated baseline spectrum.
[0014] In further aspects of the invention one or more of the
following features may be included. The infrared radiation may
comprise near infrared radiation. The infrared transmitter and the
infrared detector may be spaced a predetermined distance from a cap
of the container to a location on the neck portion of the container
to provide a fixed transmission path length across the neck portion
of the container. The method may include including displaying the
concentration of the gas determined to be in the container. The
container may be partially filled with a liquid and the interior
region of the container above the liquid constitutes a headspace,
and the fixed transmission path length may be positioned within the
headspace. The method may further include determining a temperature
proximate the container, using the detected spectrum to determine a
gas concentration in the headspace, and, from the gas concentration
in the head space and temperature proximate the container,
determining a gas concentration in the liquid. The method may
additionally include using a plurality of data points on each side
of the trough to perform a non-linear curve fitting to obtain the
baseline data points spanning the trough region and dividing the
detected spectrum by the interpolated baseline spectrum to produce
a normalized spectrum indicative of the energy received by infrared
detector. The method may also include determining an absorbance of
energy due to the gas using the normalized spectrum and using the
absorbance of energy, to calculate a concentration of the gas in
the headspace of the container. The method may further include
using the concentration of the gas in the headspace and the
temperature in the sensor region, to determine a concentration of
the gas dissolved in the liquid.
[0015] These and other features of the invention will be apparent
from the following detailed description and the accompanying
figures.
BRIEF DESCRIPTION OF THE FIGURES
[0016] Embodiments of the present invention will now be described,
by way of example only, with reference to the attached Figures,
wherein:
[0017] FIG. 1 is a cross-sectional view of an example beverage
container the carbonation of which may be measured with the gas
analyzer according to the invention;
[0018] FIG. 2A is a perspective view of the sensor unit of the gas
analyzer according to the invention;
[0019] FIG. 2B is an alternative perspective view of the sensor
unit depicted in FIG. 2A;
[0020] FIG. 3 is a cross-sectional view of the sensor unit depicted
in FIG. 2A and a perspective view of the data processing of the gas
analyzer according to the invention;
[0021] FIG. 4 is a spectrum waveform output of the sensor unit of
FIG. 2A after having passed through a sealed carbonated beverage
container;
[0022] FIG. 5 is a normalized version of the spectrum waveform
depicted in FIG. 4 processed according to an aspect of the
invention; and
[0023] FIG. 6 is a block diagram of an exemplary computing system
for the gas analyzer according to the invention.
DETAILED DESCRIPTION OF INVENTION
[0024] The disclosure and the various features and advantageous
details thereof are explained more fully with reference to the
non-limiting embodiments and examples that are described and/or
illustrated in the accompanying drawings and detailed in the
following description. It should be noted that the features
illustrated in the drawings are not necessarily drawn to scale, and
features of one embodiment may be employed with other embodiments
as the skilled artisan would recognize, even if not explicitly
stated herein. Moreover, it is noted that like reference numerals
represent similar parts throughout the several views of the
drawings.
[0025] Descriptions of well-known components and processing
techniques may be omitted so as to not unnecessarily obscure the
embodiments of the disclosure. The examples used herein are
intended merely to facilitate an understanding of ways in which the
disclosure may be practiced and to further enable those of skill in
the art to practice the embodiments of the disclosure. Accordingly,
the examples and embodiments herein should not be construed as
limiting the scope of the disclosure.
[0026] A preferred embodiment of this invention is described in the
context of a non-destructive carbon dioxide analyzer for use with
transparent or semi-transparent carbonated beverage bottles to
detect carbon dioxide concentrations in such bottles. However, this
invention is more broadly applicable to detecting concentrations of
any gaseous specious in any type (plastic, glass, etc.) or shape of
transparent or semi-transparent container.
[0027] Containers for carbonated beverages are typically formed of
a plastic material, such as polyethylene terephthalate (PET), which
may be produced using, for example, a blow molding process, such as
injection stretch blow molding. In a two-stage injection stretch
blow molding process, the plastic is first molded into a "preform"
using the injection molding process. Preforms are produced with the
necks of the bottles, including threads (the "finish") on one end.
These preforms are fed (after cooling) into a reheat stretch blow
molding machine to produce the desired bottle shape.
[0028] With the blow molding process, the bottle necks have
standard dimensions, even with varying body shapes/sizes. The
non-destructive carbon dioxide analyzer described herein takes
advantage of the standard neck dimensions, as described below. It
should be noted that any bottle/container may be used with the
non-destructive carbon dioxide analyzer described herein, provided
its neck dimensions are known.
[0029] Referring to FIG. 1, there is shown a typical plastic bottle
10 formed using the above described blow molding process. Bottle 10
includes sealing surface (not shown), which is a flat, circular top
surface forming the opening of the bottle. The sealing surface
makes direct contact with a closure/cap 12 to form a seal. Spiral
threads on the bottle below the sealing surface mesh with threads
on the inside of the closure/cap 12 to seal the bottle 10. The top
part of bottle 10 from the sealing surface to the neck ring 14 is
called the finish 16. There is a seam at the base of the neck ring
14 called the neck ring parting line 18, which marks the joining of
the finish 16 to the neck 20 of the bottle. Transitioning from the
neck 20, there is formed a shoulder 22, which increases in diameter
until the shoulder meets the sidewall 24 of the bottle, which is
the widest portion of the bottle.
[0030] In general, bottles that contain carbonated beverages are
formed using a standard size finish and neck, as formed during the
extrusion process, and the shoulder and body of the bottle, which
are formed during the blowing process, may vary from bottle design
to bottle design. By knowing standard dimensions of a particular
carbonated bottle design, one will know the cross-sectional
dimensions (i.e. the radius) of the bottle along the longitudinal
axis 26 from the sealing surface to the base of the bottle. This is
illustrated in FIG. 1, where the outline of a larger bottle 10a is
shown. As depicted by the outline of bottle 10a, the finish 16, and
neck 20 of both bottle 10 and bottle 10a are the same. Shoulder 22a
of bottle 10a is larger than shoulder 22 of bottle 10 and sidewall
24a of bottle 10a is shown to have a much larger radius than
sidewall 24 of bottle 10.
[0031] For this example of bottle designs, certain dimensions of
the finish 16 and neck 20 are depicted in FIG. 1, which are the
same for both bottles 10 and 10a. The distance from the top of cap
12 to the transition point from the neck 20/20a to the shoulder
22/22a is shown to be 38.34 mm, as indicated by line 27. The
distance from the top of cap 12 to the top of neck ring 14 is shown
to be 17.70 mm, as indicated by line 28, and the distance from the
top of neck ring 14 to the neck ring parting line 18 is 1.37 mm.
Thus, the total distance from the top of cap 12 to the neck ring
parting line is 19.07 mm (17.70 mm+1.37 mm) and from there to the
transition point between the neck 20/20a and the shoulder 22/22a is
19.27 mm (38.34 mm-19.07 mm). Between the neck ring parting line
and the transition between the neck and the shoulder, the two
bottles have the same cross-sectional dimensions. Thus, by
selecting a point in this region the radius/diameter of the bottles
will be known. For example, as indicated by radius line 29, which
is a distance d from the top of cap 12, the radius/diameter is 13
mm/26 mm.
[0032] As will be described below, knowing the radius/diameter of
one or more bottle designs, the path length of NIR energy
transmitted through the bottle may be known and used to calculate
gas concentration. According to an aspect of this invention, a
spectrum of NIR energy may be transmitted across a bottle/container
holding, among other things, one or more gaseous species, and the
absorbance of energy at a desired wavelength, corresponding to the
gaseous species, may be measured to determine the concentration of
the gaseous species. The transmitted path will typically be across
the headspace of the bottle/container, i.e. the portion of the
bottle/container above the liquid. Therefore, the gas concentration
in the headspace may first be determined and from that the gas
concentration dissolved in the liquid may be determined.
[0033] While the primary application described herein is measuring
the concentration of carbon dioxide in a carbonated beverage
bottle, this invention is more generally applicable to the
measurement of various gaseous species present in any transparent
or semi-transparent container.
[0034] By selecting a particular point along the length of a
bottle, having a known bottle design, to transmit a spectrum of NIR
energy, the radius of the bottle will be known and thus the path
length, l, of the radiation transmitted through the bottle will be
known. The path length, l, is one of the variables in the
Beer-Lambert Law equation, which may be expressed as follows:
A= lc Equation (1)
[0035] In this equation, A is the absorbance of energy, (epsilon)
is the molar absorptivity or the molar absorption coefficient and c
is the concentration of the gaseous species in the solution. With
the path length, l, known, the molar absorption coefficient, ,
being a fixed value, and the absorbance A determinable, as set
forth below, the concentration, C, may be calculated using a
non-destructive gas concentration analyzer according to this
invention.
[0036] Referring to FIGS. 2A and 2B, perspective views, and FIG. 3,
a cross-sectional view, of a sensor unit 40 of an embodiment of a
non-destructive gas concentration analyzer 30 according to this
invention is shown. The sensor unit is shown to be disposed on a
plastic bottle 42 similar to the bottle depicted in FIG. 1. Bottle
42 is of a known design and contains a carbonated beverage. Sensor
unit 40, which may be formed in a cube shape and be made of a
plastic material, includes a top surface 44, a bottom surface 46,
opposite the top surface 44, and a sensor region 48 formed between
the top surface 44 and bottom surface 46. Sensor region 48 may be
accessible through a circular aperture 50 in bottom surface 46 and
may be configured to receive the neck portion 52 and cap 54 of
bottle 42 when it is inserted into the sensor region 48, until the
cap 54 contacts the stop surface 56, thereby preventing further
insertion of bottle 42 into the sensor region 48. In this position
the outer diameter of aperture 50 rests on the shoulder 57 of
bottle 42.
[0037] Sensor unit 40 may also include a sidewall 58 which extends
from the first end 44 toward the second end 46. The side wall may
comprise four discrete side walls 58a-d, if sensor unit 40 is in
the shape of a cube, as is shown in FIGS. 2 and 3. Sensor unit 40
may also be in the shape of a cylinder, in which case sidewall 58
may be formed as one continuous surface. Sensor unit 40 may take on
various shapes as long as it meets a certain required design
feature; namely, that when it is placed on the container, it
receives the container in the sensor region such that the bottle is
positioned a desired distance, d, from stop surface 50, as shown in
FIG. 1 at line 27 and as will be described below. The desired
distance d corresponds to the position along the height of the
bottle having a known diameter or path length, 1, across the
cross-section of the bottle.
[0038] Within the sidewall 58 of sensor unit 40 is affixed an
infrared emitter 60 configured to transmit NIR radiation across the
sensor region 48 to an infrared detector or spectrometer 62, also
affixed to the sidewall 58, positioned opposite infrared
transmitter 60. Infrared transmitter 60 and infrared detector 62
are positioned such that the NIR radiation is transmitted over a
transmission path 64, aligned with the desired position along the
length of the bottle having the desired path length, 1. Thus, the
infrared transmitter 60 and infrared detector 62 are also located
distance, d, from the stop surface 56 and the top of cap 54 of
bottle 42. A temperature sensor 66 is also included to measure the
temperature within sensor region 48. Gas concentration measurements
in the liquid are dependent on temperature, so the reading of
temperature sensor is used to determine gas concentration in the
liquid from the determined gas concentration in the headspace, as
described below.
[0039] Infrared transmitter 60 and infrared detector 62, along with
the temperature sensor 68, are in communication with data
processing module 70 via cable, which may be connected to sensor
unit 40 via jack 72 and connected to data processing module 70 via
jack 74. Instead of a hard wired connection, sensor unit 40 may be
connected to processing module 70 via a wireless connection.
Alternatively, processing module 70 may be integrated into the
sensor unit 40.
[0040] The combination of sensor unit 40 and data processing module
70 form the non-destructive gas concentration analyzer 30,
according to this invention. The computing device 70 may take
various forms, including a laptop computer, a tablet, smartphone or
a dedicated handheld device. Processing module 70 may control the
transmission and reception of NIR energy as activated by a user via
a user interface on a display 76, as well as the calculations
required to determine gaseous species concentrations in bottle 42.
The gaseous species concentration may be displayed on the display
76 for the user to read.
[0041] Infrared transmitter 60 may output NIR energy across a
wavelength range of 750 to 2,500 nm (wavenumbers: 13,300 to 4,000
cm.sup.-1) or a subset of this range. The output signal from
infrared detector 62 represents the amount of the transmitted NIR
energy received after it passes through a sealed carbonated
beverage container. An example of the output of infrared detector
after having passed through a sealed carbonated beverage container
is depicted by spectrum waveform 100, FIG. 4. There is a clear
drop-out or reduction of received energy as indicated at trough
102, which is proximate the 2000 nm wavelength. This corresponds to
the wavelength at which carbon dioxide absorbs NIR energy and can
be used to determine carbon dioxide concentration. However, in
order to accurately calculate the concentration of carbon dioxide
in the bottle, a baseline spectrum representing the received NIR
spectrum when there is no carbon dioxide in the bottle must be
established. By comparing the baseline spectrum to the detected
spectrum, any artifacts in the detected spectrum caused by the
bottle material itself or the transmitter/detector may be
normalized because the baseline spectrum also incorporates those
same artifacts and rules them out, thereby leaving a curve which is
impacted only by the effects of carbon dioxide in the bottle.
[0042] For a given bottle type, a baseline spectrum may be measured
in advance and stored within processing module 70. This, however,
is cumbersome and requires that the system be preloaded with
baseline measurements for all possible bottle types to be measured.
According to an aspect of this invention, an interpolated baseline
spectrum may be derived from the detected spectrum. With this
approach the computing device does not need to be preloaded with
measured baseline spectrums for the various carbonated bottles to
be detected. Instead, the interpolated baseline spectrum may be
obtained each time a concentration measurement is made and it may
be done by using only the detected spectrum.
[0043] Referring again to FIG. 4, there is shown a baseline
spectrum 104, which was measured in advance on a bottle containing
no carbon dioxide. The measured baseline spectrum is only included
here for illustration purposes and does not need to be utilized
with this invention. In addition, there is shown an interpolated
baseline spectrum 104a obtained according to an aspect of this
invention. This may be accomplished by utilizing portions of
detected spectrum 100 outside the wavelengths at which carbon
dioxide absorbs NIR energy, e.g. on either side of the trough 102.
Trough 102 begins to dip downward at about 1000 nm and returns to
track with the baseline spectrum 104 at about 4000 nm. Therefore,
region 100a (below 1000 nm) and region 100b (above 4000 nm) on
either side of peak 102, may be utilized. By using data points on
either side of trough 102, in regions 100a and 100b, a non-linear
curve fit calculation may be made to interpolate the data points
between the regions 100a and 100b and thus form an interpolated
baseline spectrum 104a. It can be seen in FIG. 4 that the actual
measured baseline spectrum 104 is quite comparable to the
interpolated baseline spectrum 104a.
[0044] The interpolated baseline spectrum is obtained by performing
a nonlinear curve fitting to the actual detected spectrum by
excluding that portion of the spectrum where carbon dioxide
absorption occurs in the NIR, i.e. across the trough 102. The
interpolated spectrum is a mathematical reconstruction of the
absorption spectrum without carbon dioxide, i.e., exclusively due
to bottle container material. The non-linear curve fitting may be
carried out using a higher order polynomial curve fitting approach,
a spline curve fitting approach, or another suitable approach.
[0045] The interpolated baseline spectrum 104a may be used to
normalize the detected spectrum 100 by dividing detected spectrum
100 by the interpolated baseline spectrum 104a to arrive at a
normalized spectrum 110, FIG. 5. As used herein, "normalized"
refers to measurement of the carbon dioxide by ruling out any
influence of the container material on the measurement.
Consequently, any decrease in energy transmission is exclusively
due to carbon dioxide.
[0046] Normalized spectrum 110 depicts the percentage of energy
transmitted by infrared transmitter 60 that was received by
infrared detector 62 across the wavelength spectrum. In regions 112
and 114, between the trough 116, the detected energy is at 100%
versus the detected energy at peak 116, which is approximately 80%
of the transmitted energy. Thus, the amount of carbon dioxide in
this example, caused 20% of the transmitted NIR energy to be
absorbed.
[0047] Referring to Equation (1) above, the absorbance of energy,
A, due to the presence of carbon dioxide in the bottle may be
determined. With the normalized spectrum 110 representing the
transmitted energy, T, absorbance, A, may be found according to the
following equation:
A=- log 1/T Equation (2)
[0048] With the absorbance of energy, A, calculated according to
equation (2), the path length, l, known, and the molar absorption
coefficient, , being a fixed value, using Equation (1) above, the
concentration, c, of carbon dioxide in the headspace of the bottle
may be determined as follows:
Cgas=A/ l Equation (3)
[0049] From the concentration of gas in the headspace, as
determined by equation (3), the gas concentration dissolved in the
liquid, Cliq, may be calculated using the following formula:
Cgas=Cliq*H(T) Equation (4)
[0050] The gas concentration of the liquid, Cliq, from the gas
concentration in the headspace, Cgas, may be determined by using
Henry's law, H(T). Henry's law is a function of temperature. It is
know that at lower temperatures, more of the total amount of gas in
a container will be dissolved in liquid and less will be contained
in the headspace. Conversely, at higher temperatures, more of the
total gas will be in the headspace and less of the gas will be
dissolved in the liquid.
[0051] By simultaneously measuring the temperature and the
headspace gaseous concentration, Cgas, as is done by the sensor
unit 40, described above, Henry's law can yield the gaseous
concentration inside the liquid, Cliq, in the container.
H(T)=H0*exp.sup.[-DH/R*(1/T-1/T0)] Equation (5)
[0052] In this equation, DH is the enthalpy change, R is the gas
constant for the particular gaseous species being detected, T0 is a
reference temperature, T is the temperature detected by temperature
sensor 66, and H0 is the Henry's Law constant at the reference
temperature T0. Using equations (4) and (5), a look-up table may be
created and stored in memory with values for various gas
concentrations, Cgas, and corresponding gas concentration of the
liquid, Cliq, for a range of possible temperatures. Using the
calculated gas concentration and measured temperature (as described
above), the look-up table may be used to find the corresponding gas
concentration in the liquid. Here is an example of a portion of a
look-up table for carbon dioxide concentrations at various
temperatures:
TABLE-US-00001 Cgas, atm Cliq, gram/liter Temperature, celsius 1.8
5.0 0 2.4 5.0 10 2.8 5.0 15 3.2 5.0 20
[0053] As an example, for a calculated gas concentration of 1.8 atm
in the headspace of the bottle at a temperature of 0, the gas
concentration in the liquid of 5.0 g/1 may be retrieved from the
look-up table and output on the display as the measured gas
concentration in the liquid.
[0054] Non-Limiting Computing Device Examples
[0055] FIG. 6 is a block diagram of an exemplary computing device
1010 such as may be used, or portions thereof, e.g. processing
module 70, in accordance with various embodiments as described
above with reference to FIGS. 1-5. The computing device 1010
includes one or more non-transitory computer-readable media for
storing one or more computer-executable instructions or software
for implementing exemplary embodiments. The non-transitory
computer-readable media may include, but are not limited to, one or
more types of hardware memory, non-transitory tangible media (for
example, one or more magnetic storage disks, one or more optical
disks, one or more flash drives), and the like. For example, memory
1016 included in the computing device 1010 may store
computer-readable and computer-executable instructions or software
for performing the operations disclosed herein. For example, the
memory may store software application 1040 which is programmed to
perform various of the disclosed operations as discussed with
respect to FIGS. 1-5. The computing device 1010 may also include
configurable and/or programmable processor 1012 and associated core
1014, and optionally, one or more additional configurable and/or
programmable processing devices, e.g., processor(s) 1012' and
associated core (s) 1014' (for example, in the case of
computational devices having multiple processors/cores), for
executing computer-readable and computer-executable instructions or
software stored in the memory 1016 and other programs for
controlling system hardware. Processor 1012 and processor(s) 1012'
may each be a single core processor or multiple core (1014 and
1014') processor.
[0056] Virtualization may be employed in the computing device 1010
so that infrastructure and resources in the computing device may be
shared dynamically. A virtual machine 1024 may be provided to
handle a process running on multiple processors so that the process
appears to be using only one computing resource rather than
multiple computing resources. Multiple virtual machines may also be
used with one processor.
[0057] Memory 1016 may include a computational device memory or
random access memory, such as but not limited to DRAM, SRAM, EDO
RAM, and the like. Memory 1016 may include other types of memory as
well, or combinations thereof.
[0058] A user may interact with the computing device 1010 through a
visual display device 1001, 111A-D, such as a computer monitor,
which may display one or more user interfaces 1002 that may be
provided in accordance with exemplary embodiments. The computing
device 1010 may include other I/O devices for receiving input from
a user, for example, a keyboard or any suitable multi-point touch
interface 1018, a pointing device 1020 (e.g., a mouse). The
keyboard 1018 and the pointing device 1020 may be coupled to the
visual display device 1001. The computing device 1010 may include
other suitable conventional I/O peripherals.
[0059] The computing device 1010 may also include one or more
storage devices 1034, such as but not limited to a hard-drive,
CD-ROM, or other computer readable media, for storing data and
computer-readable instructions and/or software that perform
operations disclosed herein. Exemplary storage device 1034 may also
store one or more databases for storing any suitable information
required to implement exemplary embodiments. The databases may be
updated manually or automatically at any suitable time to add,
delete, and/or update one or more items in the databases.
[0060] The computing device 1010 may include a network interface
1022 configured to interface via one or more network devices 1032
with one or more networks, for example, Local Area Network (LAN),
Wide Area Network (WAN) or the Internet through a variety of
connections including, but not limited to, standard telephone
lines, LAN or WAN links (for example, 802.11, T1, T3, 56 kb, X.25),
broadband connections (for example, ISDN, Frame Relay, ATM),
wireless connections, controller area network (CAN), or some
combination of any or all of the above. The network interface 1022
may include a built-in network adapter, network interface card,
PCMCIA network card, card bus network adapter, wireless network
adapter, USB network adapter, modem or any other device suitable
for interfacing the computing device 1010 to any type of network
capable of communication and performing the operations described
herein. Moreover, the computing device 1010 may be any
computational device, such as a workstation, desktop computer,
server, laptop, handheld computer, tablet computer, or other form
of computing or telecommunications device that is capable of
communication and that has sufficient processor power and memory
capacity to perform the operations described herein.
[0061] The computing device 1010 may run any operating system 1026,
such as any of the versions of the Microsoft.RTM. Windows.RTM.
operating systems (Microsoft, Redmond, Wash.), the different
releases of the Unix and Linux operating systems, any version of
the MAC OS.RTM. (Apple, Inc., Cupertino, Calif.) operating system
for Macintosh computers, any embedded operating system, any
real-time operating system, any open source operating system, any
proprietary operating system, or any other operating system capable
of running on the computing device and performing the operations
described herein. In exemplary embodiments, the operating system
1026 may be run in native mode or emulated mode. In an exemplary
embodiment, the operating system 1026 may be run on one or more
cloud machine instances.
[0062] While the foregoing description of the invention enables one
of ordinary skill to make and use what is considered presently to
be the best mode thereof, those of ordinary skill will understand
and appreciate the existence of variations, combinations, and
equivalents of the specific embodiments and examples herein. The
above-described embodiments of the present invention are intended
to be examples only. Alterations, modifications and variations may
be effected to the particular embodiments by those of skill in the
art without departing from the scope of the invention, which is
defined solely by the claims appended hereto. The invention is
therefore not limited by the above described embodiments and
examples.
[0063] Having described the invention, and a preferred embodiment
thereof, what is claimed as new and secured by letters patent
is:
* * * * *