CA1219666A - Ultrasonic particulate sensing - Google Patents
Ultrasonic particulate sensingInfo
- Publication number
- CA1219666A CA1219666A CA000448334A CA448334A CA1219666A CA 1219666 A CA1219666 A CA 1219666A CA 000448334 A CA000448334 A CA 000448334A CA 448334 A CA448334 A CA 448334A CA 1219666 A CA1219666 A CA 1219666A
- Authority
- CA
- Canada
- Prior art keywords
- particulate
- energy
- flow
- scattered
- pulse
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
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- Investigating Or Analyzing Materials By The Use Of Ultrasonic Waves (AREA)
Abstract
Abstract of the Disclosure A method of identifying and determining the size of particulates in a flowing fluid compris-ing detecting the portion of an ultrasonic pulse scattered from a particulate at a preselected angle, converting the results into density and elasticity-related values and comparing the values with mea-sured or computed values for known particulates.
Description
I
ULTRASONIC PARTICULATE SENSING
Field of the Invention This invention relates to a method of identifying and determining -the size of particulate in a flow.
Background of the Invention In certain chemical processes, e.g., the fabrication of semiconductors, it is important that the complex chemical fluids used have the proper composition. For example, in one such process, the presence of small nickel or iron particles may be necessary, but smell particles of aluminum may destroy the end product. In another process, it may be critical to distinguish between air bubbles and oil droplets for the same reason. Also, the size of a certain type of particulate may be the important factor in some processes.
Summary _ the Invention According to the present invention there is provided a method of identifying particulate in a flow comprising:
sending an ultrasonic pulse of known energy into the flow, detecting at a preselected angle energy scattered when the pulse strikes a particulate in the flow, and using the amount of detected scattered energy in relation to the known energy of the pulse and the angle of its detection to identify the particulate.
The present invention also provides a particulate identification apparatus comprising means for transmitting an ultrasonic pulse of known energy into a flow, means for detecting the magnitude of the energy scattered when the pulse strikes .
1~9~6 a particulate in the flow, the means for detecting being disposed other than opposite the means for transmitting, and means for comparing the amount of scattered energy detected by the means for detecting with known information about known particulate so as to identify the particulate in -the flown wherein the means for receiving comprises a pair of -transducers disposed to receive at different angles the scattered energy from the particulate in the flow.
In preferred embodiments, a transducer sends an ultrasonic pulse across a fluid flow, and the pulse is partially scattered when it strikes a particulate in the fluid. The amplitude of the scattered portion of the pulse is measured by two transducers at locations which will receive scattered - lo -Jo Tao energy at different angles, and density and elastic-ity-related values for the particulate are determined based upon the amplitudes and the preselected angles at which the scattered portions of the pulse are no-ceiled. To identify the particulate, these values are compared with those fox known particulate by plotting the values, while a comparison of the am-plotted measurement provides a determination as to particulate size.
Preferred Embodiments We turn now to the structure and operation of the preferred embodiments, after first briefly desk .: .. .
cribbing the drawings.
Drawings Fig. 1 is a cross-sectional view of the apt pyrites of the preferred embodiment of the invention;
Fig. 2 is a cross-sectional view of the apt pyrites of another preferred embodiment; and Fig. 3 is a plot of amplitude-based values for a number of different types of particulate.
Structure Referring to Figure 1, there it shown a scattering detecting apparatus at 10. Apparatus 10 generally comprises a transmitting transducer 12 and a pair of receiving transducers 14, 16.
Transducer 12 is mounted in a sidewall 18 of a fluid-carrying conduit 20 so as to direct a focused pulse of ultrasonic energy across the flow, which contains a number of particulate 22 of dip-fervent types. The focal point is arranged to be at the approximate midpoint of the conduit 20. Receive in transducer 14 is mounted in the portion of the sidewall 18 generally opposite transmitting trays-. i .
I
I
dicer 12 but far enough upstream as to be outside the primary area 24 of the focused ultrasonic pulse. receiving transducer 16 is further upstream than transducer 14. Both receiving trays-closures 14, lo are however, close enough to the primary area 24 of the focused pulse to be in the transducer's shadow zone, i.e., a nearby, surrounding area which receives a greatly reduced portion of the ultrasonic energy from the pulse. The transducers are the same as that disclosed in Arts U.S. patent 4,365,515 issued December 28, 1982.
The transducers are connected to the electronic pulsing and receiving devices (no-t shown).
Operation In operation, transmitting transducer 12 sends a focused pulse of ultrasonic energy across the flow, and a particulate 22 in the primary area 24 of the focused pulse will reflect some of the energy beck to the transducer 12. At the same time, however, the particulate will also scatter a portion of the pulse that strikes it, and the scattered energy field radiates in all directions from the particulate. This scattered energy field is not uniform. Instead, its amplitude at any given place is a function (for solid particles) of the density of the particle and its shear and longitudinal waves, which are related to the elasticity of the particle.
For air bubbles and liquid droplets the amplitude is a function only of the density and the longitudinal waves, as these particulate do not support shear waves. In both cases, each individual type of par--ticulate creates its own unique scattered energy field.
Some of the scattered energy is detected by the two receiving transducers 14, 16, and the peak amplitude of detected energy is measured for each transducer. The peak amplitude is a voltage, and it is converted into a pressure amplitude by the following equation:
................... ., ,-' P = VC
where V is the measured peak amplitude voltage and C is the calibration constant. The calibration con-slant is frequency dependent, but as only one ire-quench is used, i.e., 15 MHz for the preferred em-bodiment, it can be easily measured or computed for the system.
The pressure amplitude, P, is then con-vented into a scattering amplitude or scattering strength, F, by the following equation:
' F = Pd/Po where d is the distance between the transducer and the particulate, and Pro is the pressure amplitude of the wave incident on the particulate, which is a lung-lion of the transducer used. As an approximation, d may be measured from the midpoint of the conduit dip neatly beneath the transmitting transducer.
The scattering amplitude F is related to ` the angle of incidence in the following manner:
F = + B coy where and B are constants related to the density it _~.
and elasticity of the particulate, and 9 is the angle of scattering measured from the forward direction of - the initial pulse, as shown in Figure 1. us there are two measurements for F and the Al and I are known for the receiving transducers 14, 16, a and B
may be computed, and these values will be different for different particulate. For example, nickel has '' a a of .330 and a B of -.420, while aluminum has a a of .324 and a B of -~266. As an additional disk -10 tinction, most metals have a positive and a Vega-live B, while most liquids have a negative and a positive or negative B. Silicone rubber, on the other hand, has both values negative. The portico-.
fates are thus identified by comparing these values derived from the measured peak amplitudes with the measured or computed values for known particulate.
The procedure is repeated a number of times to identify all of the different particulate in the flow and to obtain repetitive readings for different particulate of the same type The fat-, ton eliminates the possibility of a misidentification ., based on a single, erroneous reading. The a and B
results are plotted in a graph, such as that of Figure 3, which provides a visual representation of the very different values obtained from several par-ticulates. The size of the particulate is directly related to the magnitude of the scattering amplitude F so that when the particulate is identified, its size is also determined by referring back to the computed scattering amplitude. For some uses, how-. ever (eye., where only a couple of known particulate Jo of a known size may be present), the scattering am-plotted alone may serve to identify the particulate.
Jo -(Usually, however, a number of different particulate might have the same amplitude F at a given ankle.) Also, if there is only one type of unknown portico-late in a flow, the and B need not be computed for each scattering amplitude, F. Instead, the average of a number of scattering amplitudes may be used to compute a single and B value.
: Other Embodiments In another embodiment of this invention, as shown in Figure 2, transducer 50 produces an unfocus-Ed pulse having a principal lobe 52. The receiving transducers 54, 56 are located in the minor side lobe regions, and in this embodiment, they are disposed across from each other. As shown by Figure 2, the angles 91 and I for each are substantially differ-en. The operation of this embodiment is as describe Ed above.
It is also possible to use additional no-ceiling transducers in the system, but the and B
values in such a system would be determined by a least-mean-squares method. It is also possible to use the transmitting transducer as a receiving trays-dicer.
Other variations will occur to those skilled in the art.
Claims What I claim is:
. .
.
. . .
_. .
ULTRASONIC PARTICULATE SENSING
Field of the Invention This invention relates to a method of identifying and determining -the size of particulate in a flow.
Background of the Invention In certain chemical processes, e.g., the fabrication of semiconductors, it is important that the complex chemical fluids used have the proper composition. For example, in one such process, the presence of small nickel or iron particles may be necessary, but smell particles of aluminum may destroy the end product. In another process, it may be critical to distinguish between air bubbles and oil droplets for the same reason. Also, the size of a certain type of particulate may be the important factor in some processes.
Summary _ the Invention According to the present invention there is provided a method of identifying particulate in a flow comprising:
sending an ultrasonic pulse of known energy into the flow, detecting at a preselected angle energy scattered when the pulse strikes a particulate in the flow, and using the amount of detected scattered energy in relation to the known energy of the pulse and the angle of its detection to identify the particulate.
The present invention also provides a particulate identification apparatus comprising means for transmitting an ultrasonic pulse of known energy into a flow, means for detecting the magnitude of the energy scattered when the pulse strikes .
1~9~6 a particulate in the flow, the means for detecting being disposed other than opposite the means for transmitting, and means for comparing the amount of scattered energy detected by the means for detecting with known information about known particulate so as to identify the particulate in -the flown wherein the means for receiving comprises a pair of -transducers disposed to receive at different angles the scattered energy from the particulate in the flow.
In preferred embodiments, a transducer sends an ultrasonic pulse across a fluid flow, and the pulse is partially scattered when it strikes a particulate in the fluid. The amplitude of the scattered portion of the pulse is measured by two transducers at locations which will receive scattered - lo -Jo Tao energy at different angles, and density and elastic-ity-related values for the particulate are determined based upon the amplitudes and the preselected angles at which the scattered portions of the pulse are no-ceiled. To identify the particulate, these values are compared with those fox known particulate by plotting the values, while a comparison of the am-plotted measurement provides a determination as to particulate size.
Preferred Embodiments We turn now to the structure and operation of the preferred embodiments, after first briefly desk .: .. .
cribbing the drawings.
Drawings Fig. 1 is a cross-sectional view of the apt pyrites of the preferred embodiment of the invention;
Fig. 2 is a cross-sectional view of the apt pyrites of another preferred embodiment; and Fig. 3 is a plot of amplitude-based values for a number of different types of particulate.
Structure Referring to Figure 1, there it shown a scattering detecting apparatus at 10. Apparatus 10 generally comprises a transmitting transducer 12 and a pair of receiving transducers 14, 16.
Transducer 12 is mounted in a sidewall 18 of a fluid-carrying conduit 20 so as to direct a focused pulse of ultrasonic energy across the flow, which contains a number of particulate 22 of dip-fervent types. The focal point is arranged to be at the approximate midpoint of the conduit 20. Receive in transducer 14 is mounted in the portion of the sidewall 18 generally opposite transmitting trays-. i .
I
I
dicer 12 but far enough upstream as to be outside the primary area 24 of the focused ultrasonic pulse. receiving transducer 16 is further upstream than transducer 14. Both receiving trays-closures 14, lo are however, close enough to the primary area 24 of the focused pulse to be in the transducer's shadow zone, i.e., a nearby, surrounding area which receives a greatly reduced portion of the ultrasonic energy from the pulse. The transducers are the same as that disclosed in Arts U.S. patent 4,365,515 issued December 28, 1982.
The transducers are connected to the electronic pulsing and receiving devices (no-t shown).
Operation In operation, transmitting transducer 12 sends a focused pulse of ultrasonic energy across the flow, and a particulate 22 in the primary area 24 of the focused pulse will reflect some of the energy beck to the transducer 12. At the same time, however, the particulate will also scatter a portion of the pulse that strikes it, and the scattered energy field radiates in all directions from the particulate. This scattered energy field is not uniform. Instead, its amplitude at any given place is a function (for solid particles) of the density of the particle and its shear and longitudinal waves, which are related to the elasticity of the particle.
For air bubbles and liquid droplets the amplitude is a function only of the density and the longitudinal waves, as these particulate do not support shear waves. In both cases, each individual type of par--ticulate creates its own unique scattered energy field.
Some of the scattered energy is detected by the two receiving transducers 14, 16, and the peak amplitude of detected energy is measured for each transducer. The peak amplitude is a voltage, and it is converted into a pressure amplitude by the following equation:
................... ., ,-' P = VC
where V is the measured peak amplitude voltage and C is the calibration constant. The calibration con-slant is frequency dependent, but as only one ire-quench is used, i.e., 15 MHz for the preferred em-bodiment, it can be easily measured or computed for the system.
The pressure amplitude, P, is then con-vented into a scattering amplitude or scattering strength, F, by the following equation:
' F = Pd/Po where d is the distance between the transducer and the particulate, and Pro is the pressure amplitude of the wave incident on the particulate, which is a lung-lion of the transducer used. As an approximation, d may be measured from the midpoint of the conduit dip neatly beneath the transmitting transducer.
The scattering amplitude F is related to ` the angle of incidence in the following manner:
F = + B coy where and B are constants related to the density it _~.
and elasticity of the particulate, and 9 is the angle of scattering measured from the forward direction of - the initial pulse, as shown in Figure 1. us there are two measurements for F and the Al and I are known for the receiving transducers 14, 16, a and B
may be computed, and these values will be different for different particulate. For example, nickel has '' a a of .330 and a B of -.420, while aluminum has a a of .324 and a B of -~266. As an additional disk -10 tinction, most metals have a positive and a Vega-live B, while most liquids have a negative and a positive or negative B. Silicone rubber, on the other hand, has both values negative. The portico-.
fates are thus identified by comparing these values derived from the measured peak amplitudes with the measured or computed values for known particulate.
The procedure is repeated a number of times to identify all of the different particulate in the flow and to obtain repetitive readings for different particulate of the same type The fat-, ton eliminates the possibility of a misidentification ., based on a single, erroneous reading. The a and B
results are plotted in a graph, such as that of Figure 3, which provides a visual representation of the very different values obtained from several par-ticulates. The size of the particulate is directly related to the magnitude of the scattering amplitude F so that when the particulate is identified, its size is also determined by referring back to the computed scattering amplitude. For some uses, how-. ever (eye., where only a couple of known particulate Jo of a known size may be present), the scattering am-plotted alone may serve to identify the particulate.
Jo -(Usually, however, a number of different particulate might have the same amplitude F at a given ankle.) Also, if there is only one type of unknown portico-late in a flow, the and B need not be computed for each scattering amplitude, F. Instead, the average of a number of scattering amplitudes may be used to compute a single and B value.
: Other Embodiments In another embodiment of this invention, as shown in Figure 2, transducer 50 produces an unfocus-Ed pulse having a principal lobe 52. The receiving transducers 54, 56 are located in the minor side lobe regions, and in this embodiment, they are disposed across from each other. As shown by Figure 2, the angles 91 and I for each are substantially differ-en. The operation of this embodiment is as describe Ed above.
It is also possible to use additional no-ceiling transducers in the system, but the and B
values in such a system would be determined by a least-mean-squares method. It is also possible to use the transmitting transducer as a receiving trays-dicer.
Other variations will occur to those skilled in the art.
Claims What I claim is:
. .
.
. . .
_. .
Claims (8)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A method of identifying particulates in a flow comprising:
sending an ultrasonic pulse of known energy into the flow, detecting at a preselected angle energy scattered when the pulse strikes a particulate in the flow, and using the amount of detected scattered energy in relation to the known energy of the pulse and the angle of its detection to identify the particulate.
sending an ultrasonic pulse of known energy into the flow, detecting at a preselected angle energy scattered when the pulse strikes a particulate in the flow, and using the amount of detected scattered energy in relation to the known energy of the pulse and the angle of its detection to identify the particulate.
2. The method of claim 1 wherein the amount of detected scattered energy at the preselected angle is compared with the amount of detected scattered energy at the same preselected angle for known particulates to identify the particulate and determine size.
3. A method of identifying particulates in flow com-prising:
sending an ultrasonic pulse of known energy into the flow, detecting at a preselected angle energy scattered when the pulse strikes a particulate in the flow, and using the amount of detected scattered energy in relation to the known energy of the pulse and the angle of its detection to identify the particulate, wherein said detecting includes detecting at least two different portions of the scattered energy at two different preselected angles.
sending an ultrasonic pulse of known energy into the flow, detecting at a preselected angle energy scattered when the pulse strikes a particulate in the flow, and using the amount of detected scattered energy in relation to the known energy of the pulse and the angle of its detection to identify the particulate, wherein said detecting includes detecting at least two different portions of the scattered energy at two different preselected angles.
4. The method of claim 3 wherein said using the amount of detected scattered energy includes converting all the portions detected into scattering amplitudes.
5. The method of claim 4 wherein the scattering amplitudes are combined with the corresponding preselected angles to compute values related to the density and elasticity of the particulate.
6. The method of claim 5 wherein said computed values are compared with the value of known particulates at the same preselected angles.
7. A particulate identification apparatus comprising means for transmitting an ultrasonic pulse of known energy into a flow, means for detecting the magnitude of the energy scattered when the pulse strikes a particulate in the flow, said means for detecting being disposed other than opposite said means for transmitting, and means for comparing the amount of scattered energy detected by said means for detecting with known information about known particulates so as to identify the particulate in the flow, wherein said means for receiving comprises a pair of transducers disposed to receive at different angles the scattered energy from the particulate in the flow.
8. The apparatus of claim 7 wherein said pair of trans-ducers are disposed on opposite sides of the flow.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000448334A CA1219666A (en) | 1984-02-27 | 1984-02-27 | Ultrasonic particulate sensing |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000448334A CA1219666A (en) | 1984-02-27 | 1984-02-27 | Ultrasonic particulate sensing |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1219666A true CA1219666A (en) | 1987-03-24 |
Family
ID=4127279
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000448334A Expired CA1219666A (en) | 1984-02-27 | 1984-02-27 | Ultrasonic particulate sensing |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1219666A (en) |
-
1984
- 1984-02-27 CA CA000448334A patent/CA1219666A/en not_active Expired
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |