GB2226880A - Particle sizing - Google Patents
Particle sizing Download PDFInfo
- Publication number
- GB2226880A GB2226880A GB8928112A GB8928112A GB2226880A GB 2226880 A GB2226880 A GB 2226880A GB 8928112 A GB8928112 A GB 8928112A GB 8928112 A GB8928112 A GB 8928112A GB 2226880 A GB2226880 A GB 2226880A
- Authority
- GB
- United Kingdom
- Prior art keywords
- particles
- photo detectors
- size
- output signals
- light
- 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.)
- Granted
Links
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N15/00—Investigating characteristics of particles; Investigating permeability, pore-volume, or surface-area of porous materials
- G01N15/02—Investigating particle size or size distribution
- G01N15/0205—Investigating particle size or size distribution by optical means, e.g. by light scattering, diffraction, holography or imaging
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N15/00—Investigating characteristics of particles; Investigating permeability, pore-volume, or surface-area of porous materials
- G01N15/10—Investigating individual particles
- G01N15/14—Electro-optical investigation, e.g. flow cytometers
- G01N15/1456—Electro-optical investigation, e.g. flow cytometers without spatial resolution of the texture or inner structure of the particle, e.g. processing of pulse signals
Abstract
An apparatus for measuring the size of irregularly shaped particles includes two photo detectors 4, 5 so positioned that directed beams of light reflected from flat, or nearly flat, surfaces on the particles 3 cannot fall simultaneously on both photo detectors. Only those output signals from the photo detectors which are approximately equal are used to derive the size of the particles. Particle velocity may additionally be measured by using two coherent light beams as the source of illumination. <IMAGE>
Description
PARTICLE SIZING
The present invention relates to the measurement of the size of particles in two-phase flow when the shape of the particles is irregular.
Techniques exist for determining the size of particles in two-phase flow by measuring the intensity of light scattered by the particles. The intensity the scattered light is dependent upon the radius of curvature of the scattering particles. If the particles are spherical then this enables the size of the particles to be derived directly. If the particles are irregular in shape, then areas may exist which locally have very large radii of curvature, or even may be flat. Such areas produce beams of reflected rather than scattered light which have intensities much higher than those which should be produced according to the actual size of the particles.
The present invention seeks to overcome this problem.
According to the present invention there is provided an apparatus for measuring the size of irregular particles, comprising means for illuminating irregular particles the size of which it is desired to measure, means for positioning first and second photo detectors so as to receive light scattered by the particles the photo detector positioning means being such that a beam of light less than a predetermined width cannot be received by the photo detectors simultaneously, means for measuring the intensity of light falling upon each of the photo detectors and producing output signals related thereto, means for comparing the output signals from the photo detectors and producing a measurement signal indicative of the size of the particles when the output signals from the photo detectors do not differ by more than a predeterminecl amount.
The invention will now be described, by way of example, with reference to the accompanying drawings, in which,
Figure 1 illustrates schematically an apparatus
embodying the invention and
Figure 2 illustrates the action of the apparatus of
Figure 1.
Referring to Figure 1, a beam of light 1 from a pulsed laser source 2 is brought to a focus in a region of particulate flow 3. Two photo detectors 4 and 5 are positioned in a plane approximately perpendicular to the direction of propagation of the beam of light 1 with an angular separation of some 150. This is sufficient to ensure that any narrow beam of scattered light will not be received simultaneously by the photo detectors 4 and 5.
Signals from the photo detectors 4 and 5 are processed in a processor 6. The maximum intensity of the scattered light during each signal burst received by each photo detector is measured and compared. Typical pairs of signals are shown in Figure 2. Provided the measured intensities are not too dissimilar, the mean signal is accepted and compared with calibration values to derive a measure of the size of the particles.
The comparator 6 may derive either the difference between the signals from the photo detectors 4 and 5 or their ratio. The comparison values of the two photo detectors signals also may be used to provide an indication of the shape of the particles because the distribution of all the measured signal values will be characteristic of the degree of irregularity of the particles. Also if two coherent laser beams are used, then the velocity of the particles may be measured by means of laser Doppler anemometry.
Although the apparatus as has been described makes use of a laser light source, any bright light source can be used.
Claims (5)
1 An apparatus for measuring the size of irregular particles, comprising means for illuminating irregular particles the size of which it is desired to measure, means for positioning first and second photo detectors so as to receive light scattered by the particles the photo detector positioning means being such that a beam of light less than a predetermined width cannot be received by the photo detectors simultaneously, means for measuring the intensity of light falling upon each of the photo detectors and producing output signals related thereto, means for comparing the output signals from the photo detectors and producing a measurement signal indicative of the size of the particles when the output signals from the photo detectors do not differ by more than a predetermined amount.
2 Apparatus according to claims wherein the comparater is adapted to derive the difference between the output signals from the photodetectors.
3 Apparatus according to claims 1 wherein the comparater is adapted to derive the ratio of the output signals from the detectors.
4 Apparatus according to any of claims 1 to 3 wherein the means for illuminating the particles includes means for producing two coherent beams of light and there is included means for detecting changes in the frequency of the scattered light to determine the velocity of the particles.
5 Apparatus for measuring the size of irregular particles substantially as hereinbefore described and with reference to the accompanying drawings.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB888829482A GB8829482D0 (en) | 1988-12-16 | 1988-12-16 | Particle sizing |
Publications (3)
| Publication Number | Publication Date |
|---|---|
| GB8928112D0 GB8928112D0 (en) | 1990-02-14 |
| GB2226880A true GB2226880A (en) | 1990-07-11 |
| GB2226880B GB2226880B (en) | 1992-12-02 |
Family
ID=10648667
Family Applications (2)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB888829482A Pending GB8829482D0 (en) | 1988-12-16 | 1988-12-16 | Particle sizing |
| GB8928112A Expired - Fee Related GB2226880B (en) | 1988-12-16 | 1989-12-12 | Particle sizing |
Family Applications Before (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB888829482A Pending GB8829482D0 (en) | 1988-12-16 | 1988-12-16 | Particle sizing |
Country Status (1)
| Country | Link |
|---|---|
| GB (2) | GB8829482D0 (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2009042619A1 (en) * | 2007-09-24 | 2009-04-02 | Donald John Holve | Laser-based apparatus and method for measuring agglomerate concentration and mean agglomerate size |
| WO2012016815A1 (en) | 2010-08-04 | 2012-02-09 | Robert Bosch Gmbh | Scattered light measurement method |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3835315A (en) * | 1972-12-06 | 1974-09-10 | Us Commerce | System for determining parameters of a particle by radiant energy scattering techniques |
| JP2641927B2 (en) * | 1988-11-16 | 1997-08-20 | 興和株式会社 | Particle measurement device |
-
1988
- 1988-12-16 GB GB888829482A patent/GB8829482D0/en active Pending
-
1989
- 1989-12-12 GB GB8928112A patent/GB2226880B/en not_active Expired - Fee Related
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2009042619A1 (en) * | 2007-09-24 | 2009-04-02 | Donald John Holve | Laser-based apparatus and method for measuring agglomerate concentration and mean agglomerate size |
| US7782459B2 (en) | 2007-09-24 | 2010-08-24 | Process Metrix | Laser-based apparatus and method for measuring agglomerate concentration and mean agglomerate size |
| WO2012016815A1 (en) | 2010-08-04 | 2012-02-09 | Robert Bosch Gmbh | Scattered light measurement method |
| DE102010038897A1 (en) | 2010-08-04 | 2012-02-09 | Robert Bosch Gmbh | Scattered light measurement method |
| US8659756B2 (en) | 2010-08-04 | 2014-02-25 | Robert Bosch Gmbh | Scattered light measuring method |
Also Published As
| Publication number | Publication date |
|---|---|
| GB8928112D0 (en) | 1990-02-14 |
| GB8829482D0 (en) | 1989-02-01 |
| GB2226880B (en) | 1992-12-02 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PCNP | Patent ceased through non-payment of renewal fee |
Effective date: 19931212 |