EP0968408A2 - Procede de mesure granulometrique - Google Patents

Procede de mesure granulometrique

Info

Publication number
EP0968408A2
EP0968408A2 EP98916951A EP98916951A EP0968408A2 EP 0968408 A2 EP0968408 A2 EP 0968408A2 EP 98916951 A EP98916951 A EP 98916951A EP 98916951 A EP98916951 A EP 98916951A EP 0968408 A2 EP0968408 A2 EP 0968408A2
Authority
EP
European Patent Office
Prior art keywords
pass
variable
signals
measuring
linear operation
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.)
Withdrawn
Application number
EP98916951A
Other languages
German (de)
English (en)
Inventor
Ulrich Riebel
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Individual
Original Assignee
Individual
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Individual filed Critical Individual
Publication of EP0968408A2 publication Critical patent/EP0968408A2/fr
Withdrawn legal-status Critical Current

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
    • 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
    • G01N15/0211—Investigating a scatter or diffraction pattern
    • G01N2015/0222—Investigating a scatter or diffraction pattern from dynamic light scattering, e.g. photon correlation spectroscopy

Definitions

  • the invention relates to a method for particle size measurement by measuring the attenuation of radiation after passing through a defined measuring section in which a disperse system is located.
  • disperse systems In many areas of process engineering, an exact characterization of disperse systems is necessary.
  • a disperse phase i.e. solid, liquid or gaseous particles in a continuous phase, i.e. a liquid or gaseous phase.
  • the particle size distribution and the particle volume concentration are generally used for characterization. The sizes should be measured as possible in-situ so that errors due to sampling, dilution etc. can be avoided. Furthermore, simple and inexpensive processes for process control are desired.
  • the object of the invention is to provide an improved method for particle size measurement, in which calibration with the material to be measured is no longer necessary.
  • the transmission signal which fluctuates over time, is recorded with variable temporal or spatial resolution.
  • the transmission signals are subjected to a non-linear operation and the result of the non-linear operation is presented as a spectral curve, i.e. as a function of spatial or temporal resolution, displayed and evaluated.
  • the temporal fluctuations of the transmission signal in addition to the electrical signal noise, are an expression of the probability of residence of different particle size classes in the measurement volume.
  • the information about the particle size distribution and particle volume concentration contained in the fluctuation of the transmission signal is used systematically for measuring the particle sizes according to the present invention.
  • An essential method step of the method according to the invention is to subject the transmission signals to a non-linear operation.
  • the nonlinear operation can be, for example, a squaring, a logarithming or also an analytical function, for example of the following form (T) N or exp ⁇ T ⁇ , where T is the transmission and N is any real number.
  • T is the transmission and N is any real number.
  • other non-linear operations can also be used in the method according to the invention.
  • the signal is advantageously acquired with a high temporal and spatial resolution and displayed and evaluated as an auto power density spectrum, which is a special non-linear operation.
  • the signal acquisition with variable temporal resolution can be realized by various low-pass, high-pass and / or band-pass combinations and the result of the non-linear operation can be displayed and evaluated as a function of the time constant of the low pass, high pass and / or band pass.
  • the signals can be recorded digitally and subjected to a moving averaging with variable averaging parameters as digital low-pass, high-pass and / or band-pass.
  • the size and / or shape of the cross section of the measuring beam can be variable in order to implement an optical low pass, high pass and / or band pass.
  • an advantageous embodiment of the method consists in the combination of the following method steps:
  • the primary beam can be divided into several partial beams and guided through the measuring section in the form of these divided partial beams.
  • variable optical low-pass filters or band-pass filters can be implemented by adding or subtractively superimposing transmissions measured with the partial beams.
  • the non-linear operation can be carried out by a non-linear combination, for example a multiplication, of the transmission of two or several partial beams can be realized.
  • the partial beams can run through the suspension in different directions. On the one hand, they can run parallel to a plane that is spanned transversely to the direction of flow. Alternatively, they can run parallel to a plane that is spanned parallel to the direction of flow of the suspension.
  • the partial beams can penetrate at one point, ie the measuring volume. Alternatively, they can cross each other in different planes, which are seen one above the other in the direction of flow of the suspension.
  • the measurement and evaluation is described here by way of example for a method in which optical signal detection with different low-pass characteristics is realized by varying the diameter of the measuring beam.
  • the instantaneous transmission T D ⁇ t> is measured continuously with, for example, 10 different beam diameters D, then the non-linear operation (NLO, in our example the squaring) is carried out separately for each measured value, and after this NLO, the 10 beam diameter the mean of the signal, E D ⁇ T 2 > formed separately.
  • NLO non-linear operation
  • the mean value of the continuous measured values is formed for each of the 10 beam diameters; this gives (within the inevitable error limits) the same value E ⁇ T> for all beam diameters.
  • T D only jumps between the values 0 (blockage of the beam by a particle) and 1 (full transmission of the beam through a gap between the particles), see Fig. 1.
  • D «x is fulfilled once, D can be reduced within wide limits (ie by many decades) without the course T D ⁇ t> changes significantly.
  • T D ⁇ t> in the range D »x the signal is almost constant over time with only slight fluctuations. With a further enlargement of D there are no significant changes.
  • the exact shape and height of the S-shaped step depend on the chosen NLO.
  • FIG. 2 shows a curve of E D ⁇ T 2 > for monodisperse glass spheres, plotted against the beam diameter D / x normalized with the particle size.
  • the particle size can be read directly from a diagram according to FIG. 2 or 3, specifically from the position of the half value of the step height on the D / x axis. The following applies:
  • Gig. 3 be resolved according to the particle size sought.
  • the particle concentration for example expressed by the projection surface concentration C Pf (particle projection surface / suspension volume) can also be calculated directly, namely according to the Bouger-Lambert-Beer equation and with Gig. (1):
  • S ⁇ X j , D> as a "statistical coefficient" is a function of the ratio D / X j and is read from the standardized representation according to FIG. 3 as
  • Cp f is the total projection surface concentration of the particles
  • ⁇ X j the width of the respective particle size interval j.
  • the width of the S-shaped curve which can be represented as the quotient D 90 / D ⁇ 0 (position of the 90% value or 10% value of the step height), provides a measure of the width in comparison with the width for a monodisperse fraction the PGV.
  • an evaluation can be carried out by storing a large number of curve profiles, which have been measured or calculated for known particle distributions, in a file. The course most similar to the measured curve can then be selected from the file, whereby the particle distribution can be determined if the file is sufficiently large. It is also possible to train a neural network with signals of known particle distributions and then use it for the evaluation of the measured curves.
  • Equivalent to a measurement with different beam diameters is the measurement of the transmission with a single measurement beam that is as thin as possible, and the application of this signal to, for example, 10 different electrical low-pass filters with different time constants, which process the signal simultaneously.
  • the 10 low-pass filters now deliver 10 different output signals, which are subjected to the same NLO (squaring in our example) in parallel and, when averaging is carried out, different mean values E ⁇ ⁇ T 2 > deliver.
  • the mean value of the original transmission signal is again formed, also squared, and gives the value E 2 ⁇ T>.
  • the invention provides a way to measure with a variable time ⁇ (this is usually much easier to implement than measuring beams with different diameters), and at the same time to measure with a single, well-known spatial low-pass filter D ' . Due to the complete analogy of both curves, it is now possible to identify
  • the speed v can also be determined by any independent measurement method. If a measuring method with several (minimum at least 2) partial beams is realized, then a particularly advantageous embodiment consists in that the speed of the particles is determined in a known manner from the cross-correlation of the transmission of two partial beams.
  • Two measuring beams are guided in such a way that they cross each other within the measuring section, the smallest distance between the measuring beams being denoted by ⁇ , see FIG. 5.
  • the two transmissions Ti, T 2 of the two beams are recorded separately and with high temporal and spatial resolution.
  • a high spatial resolution is achieved in particular in that the two beams 1 and 2 are focused at the focal points B and B 2 at the point of intersection.
  • the distance ⁇ can be varied by, for example, pivoting beam 1 in the plane spanned by B ⁇ B 2 and D or shifting it in parallel.
  • the preferred embodiment provides that ⁇ can be reduced to zero so that the focal points Bi, B 2 coincide.
  • the values ⁇ n are in no way correlated with the values ⁇ 2 ⁇ , but show fluctuations that are statistically independent of one another. This applies to all ⁇ - ⁇ , ⁇ 2 j, if the distance ⁇ is greater than the largest occurring particles and the particles move perpendicular to the distance ⁇ spanned by Bi, B 2 . In this case, if the product ⁇ -u • ⁇ 2 j is formed from the two transmissions, the expected value of the product ⁇ -u ⁇ ⁇ 2i is equal to the product of the expected values:
  • NLO non-linear operation
  • a variant of the embodiment provides that the distance ⁇ spanned by the points Bi, B 2 is aligned parallel to the direction of movement of the particles. If one now selects ⁇ > x, the signal components ⁇ -i * and ⁇ 2 * are identical with a time shift, for example when transporting in the direction from B: to B 2 :
  • v is the velocity of the particles.
  • the transmissions T1 and T2 are now measured with a high temporal resolution, the cross-correlation product Ti ⁇ t> ⁇ T 2 ⁇ t + ⁇ > is formed with a variable temporal shift ⁇ and log (E ⁇ T ⁇ ⁇ t> ⁇ T 2 ⁇ t + t>) as a function of the normalized time shift x ⁇ v (cf. FIG. 7).
  • the variation of ⁇ at v // B 1 B 2 is therefore analogous to a variation of ⁇ at v 1 B 1 B 2 .

Landscapes

  • Chemical & Material Sciences (AREA)
  • Dispersion Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • Health & Medical Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Biochemistry (AREA)
  • General Health & Medical Sciences (AREA)
  • General Physics & Mathematics (AREA)
  • Immunology (AREA)
  • Pathology (AREA)
  • Analysing Materials By The Use Of Radiation (AREA)
  • Investigating Or Analysing Materials By Optical Means (AREA)

Abstract

L'invention concerne un procédé de mesure granulométrique par mesure de l'atténuation d'un rayonnement après passage dans un parcours de mesure déterminé dans lequel se trouve un système dispersé. L'invention est caractérisée en ce que le signal de transmission fluctuant en fonction du temps est capté avec une résolution temporelle ou spatiale. Ces signaux de transmission captés sont ensuite soumis à une opération non linéaire dont le résultat est représenté et évalué sous forme d'une variation spectrale, c'est-à-dire en fonction de la résolution spatiale ou temporelle.
EP98916951A 1997-03-19 1998-03-12 Procede de mesure granulometrique Withdrawn EP0968408A2 (fr)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
DE19711494 1997-03-19
DE19711494A DE19711494C1 (de) 1997-03-19 1997-03-19 Verfahren zur Partikelgrößenmessung
PCT/EP1998/001490 WO1998041840A2 (fr) 1997-03-19 1998-03-12 Procede de mesure granulometrique

Publications (1)

Publication Number Publication Date
EP0968408A2 true EP0968408A2 (fr) 2000-01-05

Family

ID=7823926

Family Applications (1)

Application Number Title Priority Date Filing Date
EP98916951A Withdrawn EP0968408A2 (fr) 1997-03-19 1998-03-12 Procede de mesure granulometrique

Country Status (6)

Country Link
US (1) US6587200B1 (fr)
EP (1) EP0968408A2 (fr)
JP (1) JP2001516451A (fr)
AU (1) AU7035598A (fr)
DE (1) DE19711494C1 (fr)
WO (1) WO1998041840A2 (fr)

Families Citing this family (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE10001701B4 (de) * 2000-01-18 2006-03-30 Topas Gmbh Fotometer
US7181095B1 (en) 2003-07-29 2007-02-20 Cisco Technology, Inc. Low loss, noise filtering multiplexer/demultiplexer for reconfigurable OADMs
JP2008527359A (ja) * 2005-01-17 2008-07-24 バイオフォス・アーゲー 粒子の動的パラメータを測定するための方法およびデバイス
US7440102B1 (en) 2005-08-26 2008-10-21 The United States Of America As Represented By The Secretary Of The Army Systems and methods for analyzing polarized light scattered from a sample
WO2008009403A1 (fr) * 2006-07-17 2008-01-24 Biophos Ag Dispositif mobile pour une analyse de particules par corrélation d'images

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US3733548A (en) * 1971-04-28 1973-05-15 Coulter Electronics Apparatus and method for measuring particle concentration of a suspension passing through a sensing zone
US3779070A (en) * 1971-11-23 1973-12-18 Autometrics Co Particle size and percent solids monitor
US3975084A (en) * 1973-09-27 1976-08-17 Block Engineering, Inc. Particle detecting system
SE393864B (sv) 1975-12-01 1977-06-20 Svenska Traeforskningsinst Forfarande for koncentrationsbestemning
SE7806922L (sv) 1978-06-15 1979-12-16 Svenska Traeforskningsinst Forfarande och anordning for att indikera storleksfordelningen av i ett strommande medium befintliga partiklar
DE3138159A1 (de) * 1981-09-25 1983-04-14 Gkss - Forschungszentrum Geesthacht Gmbh, 2054 Geesthacht Verfahren und vorrichtung zur (gamma)-transmissionsanalyse von mehrkomponenten-gemischen in gegenwart grobkoerniger komponenten
SE453128B (sv) * 1981-10-01 1988-01-11 Svenska Traeforskningsinst Forfarande for att bestemma medelpartikelradie och/eller medelpartikellengd
DE3344122A1 (de) * 1983-12-07 1985-06-20 Kernforschungszentrum Karlsruhe Gmbh, 7500 Karlsruhe Verfahren und einrichtung zur bestimmung der mittleren partikelgroesse von aerosolen
DE3412620A1 (de) 1984-04-04 1985-10-17 Basf Ag, 6700 Ludwigshafen Laseroptische anordnung zur messung des dispergiergrades in stroemenden systemen
JPH0643949B2 (ja) * 1988-10-03 1994-06-08 大塚電子株式会社 粒径測定装置
US5095451A (en) * 1989-07-13 1992-03-10 E. I. Du Pont De Nemours And Company Centrifuge particle size analyzer
US5094532A (en) * 1989-11-07 1992-03-10 General Signal Corporation Method and apparatus for measuring small particle size distribution
US5121629A (en) * 1989-11-13 1992-06-16 E. I. Du Pont De Nemours And Company Method and apparatus for determining particle size distribution and concentration in a suspension using ultrasonics
US4988190A (en) * 1990-01-05 1991-01-29 Trustees Of Princeton University Absorption line filter window and method for velocity measurements by light scattering

Non-Patent Citations (1)

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Title
See references of WO9841840A2 *

Also Published As

Publication number Publication date
AU7035598A (en) 1998-10-12
WO1998041840A2 (fr) 1998-09-24
JP2001516451A (ja) 2001-09-25
DE19711494C1 (de) 1998-10-15
US6587200B1 (en) 2003-07-01
WO1998041840A3 (fr) 1998-12-03

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