CN85104282A - Apparatus for measurement of particle size distribution - Google Patents
Apparatus for measurement of particle size distribution Download PDFInfo
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- CN85104282A CN85104282A CN85104282.1A CN85104282A CN85104282A CN 85104282 A CN85104282 A CN 85104282A CN 85104282 A CN85104282 A CN 85104282A CN 85104282 A CN85104282 A CN 85104282A
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- suspending liquid
- size distribution
- centrifugal force
- particle size
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- 239000002245 particle Substances 0.000 title claims abstract description 121
- 238000005259 measurement Methods 0.000 title claims description 11
- 239000007788 liquid Substances 0.000 claims abstract description 72
- 239000008187 granular material Substances 0.000 claims abstract description 39
- 230000033001 locomotion Effects 0.000 claims abstract description 39
- 238000013461 design Methods 0.000 claims description 2
- 239000000725 suspension Substances 0.000 claims description 2
- 230000031700 light absorption Effects 0.000 abstract description 7
- 230000003287 optical effect Effects 0.000 abstract description 3
- 238000004364 calculation method Methods 0.000 abstract description 2
- 230000001915 proofreading effect Effects 0.000 abstract description 2
- 230000002939 deleterious effect Effects 0.000 abstract 1
- 239000006194 liquid suspension Substances 0.000 abstract 1
- 230000005484 gravity Effects 0.000 description 10
- 238000001514 detection method Methods 0.000 description 8
- 238000005070 sampling Methods 0.000 description 8
- 238000000034 method Methods 0.000 description 7
- 230000002153 concerted effect Effects 0.000 description 6
- 230000000694 effects Effects 0.000 description 4
- 238000010521 absorption reaction Methods 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 238000012937 correction Methods 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 230000010354 integration Effects 0.000 description 2
- 230000001419 dependent effect Effects 0.000 description 1
- 238000009795 derivation Methods 0.000 description 1
- 230000003292 diminished effect Effects 0.000 description 1
- 238000000892 gravimetry Methods 0.000 description 1
- 238000007654 immersion Methods 0.000 description 1
- 230000008676 import Effects 0.000 description 1
- 238000012856 packing Methods 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 230000011664 signaling Effects 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
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Abstract
Utilize centrifugal force field to measure a kind of device of particle size distribution.It comprises a kind of structure that makes the suspending liquid rotation; Be used to detect a kind of optical unit of suspending liquid to the absorption of light, and a kind of microcomputer.The particle that the suspending liquid suspension is to be detected, the size distribution of particle is with measured.Optical unit is measured the variation of the granule density relevant with the time, and this variation is because the centrifugal force field that the suspending liquid rotation is produced forces movement of particles to cause.Microcomputer provides a memory, be used to store formula according to the granule density change calculations particle size distribution of measuring, and be used for proofreading and correct in centrifugal force field because the formula of the deleterious effect that non-parallel movement of particles causes, this formula has provided the particle size distribution that does not have non-parallel movement of particles error.
Description
The invention relates to the measurement mechanism of particle size distribution, especially relate to a kind of device that utilizes centrifugal force field to measure particle size distribution.
If a kind of suspending liquid itself just is in the centrifugal force field that is produced by the suspending liquid rotation.Thereby be suspended in the effect that all solids particle in the suspending liquid all is subjected to corresponding power separately, and beginning is moved in suspending liquid.The motion of these particles can be used to measure the size distribution of particle.In such cases, particle " immersion " is in liquid medium, and liquid medium and particle have constituted suspending liquid together, so act on making a concerted effort on the particle, is the summation of centrifugal force and " quiet buoyancy ".In centrifugal force field, quiet buoyancy is " entad ", it not only depends on Media density, and depend on position in the suspending liquid, it is different from the common quiet buoyancy in the gravity field, utilizes centrifugal force field to measure a kind of conventional equipment of particle size distribution, generally includes a sampling receptacle, a machinery and a granule density detecting device that makes the sampling receptacle high speed rotating.Sampling receptacle is used for a kind of suspending liquid that contains particle to be measured of splendid attire, and particle size distribution will be measured.Detect particle suspending in a kind of suitable liquid medium by handle, thereby prepared suspending liquid.Along with the high speed rotating of the sampling receptacle that comprises particle to be measured, because the centrifugal force field that rotation produces makes the particle setting in motion in suspending liquid.Movement of particles makes local granule concentration change (initial whole suspending liquid is uniform) with the time of rotation.The movement velocity of particle be decided by to act on the particle centrifugal force and to calm buoyancy, and the viscosity of medium.In addition, centrifugal force and quiet buoyancy also depend on the size and the position of particle.So on a certain position in suspending liquid, the variation that granule density is relevant with the time has provided the information about particle size distribution.By said granule density detecting device in this device, can detect granule density.
In the method for such measurement particle size distribution, should be noted that certain factor that has nothing to do with grain size also influences the granule density of observation.Act on the power centrifugal force just not on the particle, and also have quiet buoyancy, two kinds of power is not parallel to each other but acting on the particle radially, therefore, on a certain position near the rotation center of suspending liquid, detected granule density is bigger, and vice versa.Inventor of the present invention has recommended a kind of measuring method, is used for proofreading and correct owing to non-parallel motion measuring the error of introducing in particle size distribution, and has obtained successful result.
By the way, place the particle of the suspending liquid of centrifugal field, the quiet buoyancy that is subjected to is to be proportional to the centrifugal force that acts on this particle, but its direction is opposite with the centrifugal force direction.In other words, the quiet buoyancy in the centrifugal force field is centripetal force.So if act on centrifugal force on the particles suspended greater than the quiet buoyancy that acts on the same suspended particle, so, it still is a centrifugal force with joint efforts, so the direction of motion of particle is to leave the rotation center of suspending liquid.On the contrary, if quiet buoyancy greater than centrifugal force, this particle is subjected to the centripetal force effect so, its motion is towards the rotation center of suspending liquid.Know that from the description of above non-parallel kinetic error about particle the centrifugal force motion of particle cause that observable surface particles concentration ratio is less, and the centripetal force motion causes that observable granule density is bigger.Situation is promptly so right, and in order to revise the error that produces owing to nonparallel movement of particles, measuring method need be designed to be applicable to two kinds of directions of movement of particles.
The purpose of this invention is to provide a kind of centrifugal force field of utilizing, measure the device of particle size distribution, this device is made and be not subjected to nonparallel centrifugal motion of particle or the entad influence of motion in centrifugal force field.
Another object of the present invention is that this device is designed to also can utilize the gravimetry particle size distribution.
Principle of the present invention is as follows:
In the centrifugal force field that suspending liquid rotation produces, be in particle speed V in the suspending liquid in this centrifugal force field and be decided by to act on centrifugal force and centripetal force on the particle, and be decided by Stokes (StoRes) law.As a result, movement of particles speed V is provided by following formula;
V= (Rω
2(P
1-P
p)DP
2)/(18n) ……（1）
In addition, R be by the suspending liquid rotation center to measured particle position, ω be the rotation angular velocity, P
1Be the density of the liquid medium of suspending liquid, P
pBe particle density, Dp is the diameter of particle, and η is the viscosity of liquid medium.In this formula, of V on the occasion of (+) (at P
1＞P
pSituation under obtain) the expression particle does entad motion, and when V is a negative value (-) (at P
1＜P
pSituation under obtain) the expression centrifugal motion.
When suspending liquid rotates, has the movement velocity separately that all suspended particles of different-diameter provide with formula (1).So the concentration of local granule in the suspending liquid after suspending liquid rotation beginning, As time goes on changes.Use the granule density detecting device, can observe the time relationship that granule density changes on a certain position in the suspending liquid.On the other hand, the inverse by the derivation of equation (1) can obtain having diameter D to the integration of R
pParticle, arrive the granule density required time t in detection position by the arbitrary end of suspending liquid.
Integration ∫ (1/V) dR provides:
……（2）
With
……（3）
These two formula are respectively for entad moving and centrifugal motion.In formula, (=ω/2 π) is per second rotation number, R
1, R
2, and R
3Be respectively the distance of the outer end points of suspending liquid, promptly observe the distance of granule density position, and the distance of the interior end points of suspending liquid, all range observations all rise from the suspending liquid rotation center.Formula (2) and (3) show that particle arrives and detects granule density position R
2The affiliated time, reduce along with the increase of particle diameter.So, be certain certain value if observe granule density at time t, so at this moment between, all diameters all will be by granule density detection position R greater than particle that obtain by formula (2) (perhaps formula (3)) and the diameter t correspondence
2By the granule density that observes, the time t when detecting granule density, and the relation between the diameter that is linked by formula (2) (or formula (3)) and time t can derive the size distribution of particle.
Yet the influence of non-parallel movement of particles on the observation granule density of above narration do not considered in the description of more than measuring particle size distribution.When acting under the situation that be centripetal force making a concerted effort on the particle, that is to say, because P
1＞P
p, in centrifugal force field, quiet buoyancy (centripetal force) surpasses owing to the centrifugal force of suspending liquid turning effort on particle, and the direction of movement of particles is pointed to the rotation center of suspending liquid, and the tangential spacing that they have is more and more narrow, as shown in Figure 2.This kind situation makes granule density become big.Situation is opposite therewith, acting under the situation that be centrifugal force making a concerted effort on the particle, that is to say, centrifugal force is greater than quiet buoyancy (centripetal force) (because P
1＜P
p), particle motion is the direction of outwards dispersing from the suspending liquid rotation center, their tangential spacing broadens, as shown in Figure 1.Thereby granule density is diminished.
In order to make the effect of these non-parallel movement of particles understand easily; consider that at first all suspended particle has the suspending liquid of same diameter; and further suppose; suspending liquid is in the gravity field; owing to be subjected to same (downwards) gravity and same (making progress) general quiet buoyancy; all particle or move downward (in the situation of gravity greater than quiet buoyancy) parallel to each other in suspending liquid, (in the situation of quiet buoyancy greater than gravity) perhaps moves upward.In this case, the granule density of observation is a constant, as Fig. 3 describes qualitatively, has passed through the concentration detection position up to all particles, and granule density just is reduced to zero suddenly.The situation of planting therewith is opposite, if this kind suspending liquid places centrifugal force field, narrates as above, act on making a concerted effort on the particle and be entad or centrifugal.Particle is subjected to centripetal force and moves along assembling direction, thus the granule density that observes temporarily increase, as Fig. 4 qualitatively shown in, reduced to before zero at granule density.All particles all pass through the concentration detection position.On the other hand, making a concerted effort is the situation of centrifugal force, and movement of particles is radially dispersed (Fig. 2), owing to dispersing movement of particles and all particle strokes two kinds of reasons by the concentration detection position, so the concentration of observation particle is reduced to zero monotonously as shown in Fig. 5 is qualitative.Under the unequal situation of suspended particle diameter, also seen the trend that the granule density relevant with the time changes, but had wideer distribution.Under any circumstance, the particle that observes in centrifugal force field not only depends on the stroke of particle by the concentration detection position over time, and depends on the variation by tangential spacing between the non-parallel kinetic particle of particle.
Influence on non-parallel movement of particles changes granule density can be revised with two groups of formula of formula (4) and formula (5).Formula (4) and formula (5), provide respectively entad movement of particles and the excessive concentration C i of centrifugal movement of particles.In these formula, be to have infinitely small diameter (D CO(=1) with respect to particle
p=0) excessive concentration (oversize Concentration); C
1, C
2-C
2nBe the excessive concentration with respect to all size particle: r
1, r
2,-r
2nBe and observation concentration dependent parameter; Subscript 1,2 ,-2n is the numeral that shows the grain size grouping, the grouping of less digitized representation smaller particles correspondence; K is a constant, is decided by the distance of the outer end points of suspending liquid and the distance of detectable concentration position, and the measurement of these two kinds of distances all rises from the suspending liquid rotation center; K
1Also be constant, be decided by the distance of interior end-point distances of suspending liquid and concentration detection position, the measurement of these two kinds of distances all rises from the suspending liquid rotation center.
According to device of the present invention, be equipped with a kind of memory, so that store respectively two kinds of granule density correction programs that obtain according to formula (4) and formula (5).And this device is designed to select for use a program in two programs, to observe with entad motion or the corresponding granule density of centrifugal motion are proofreaied and correct.
Referring to accompanying drawing, below the present invention is described in further detail, wherein:
Fig. 1 and Fig. 2 illustrate in the suspending liquid of centrifugal force field the accompanying drawing of movement of particles;
Fig. 3 shows that in the suspending liquid of gravity field granule density changes qualitatively;
Fig. 4 and Fig. 5 show that granule density changes qualitatively in the suspending liquid of centrifugal force field;
Fig. 6 represents the formation of the embodiment of the invention;
Fig. 7 represents with above embodiment, measures the process flow diagram of particle size distribution program.
At first according to Fig. 6, describe the formation of the embodiment of the invention, the sampling receptacle 1 that is contained on the rotating disk 2 fills a kind of suspending liquid, and wherein the size distribution of suspended particle has to be determined.Rotate rotating disks 2 with motor 3, make sampling receptacle 1 rotation and make suspending liquid place centrifugal force field.4, one slits 6 of a light source and photo-detector 5 have been formed the detecting unit of light absorption, are used to detect the absorption that suspending liquid gives the light relevant with granule density on the allocation.Be transmitted to the light intensity of photodetector 5 by suspending liquid, provided the concentration of particle.Position detector 7 make have only when rotary sample container 1(thereby, suspending liquid) forward to when giving allocation, photodetector just has output, can shine suspending liquid at this position light source 4.The output signal of photodetector 5 is amplified the back by amplifier 8 and is transformed into digital signal with a-d converter 9, by input-output interface 13, is input to microprocessing unit (CPU) 12 then.CPU12 and timer 10(by the input one output interface 14), random access memory (RAM) 15, keyboard 16, read-only memory 11 links to each other with display unit 17.Timer 10 measurements are added to suspending liquid from centrifugal force and begin the back elapsed time.Random access memory (RAM) 15 has the storage portions that is used to store different measuring condition and result of calculation.Keyboard 16 is used to put location survey amount condition and starting is measured.Read-only memory 11 is stored formula (2) and (3), this two formula and particle diameter D
pAnd have this diameter D
pParticle to arrive the required time t in suspending liquid middle particle concentration detection position relevant; It also stores formula (4) and formula (5) and other data that is used to revise non-parallel movement of particles effect.The rotation of motor drive controller 18 control motors 3.Change relevant a series of optical signallings with granule density on certain position in the suspending liquid, send from photodetector 5, by amplifier 8, analog digital converter 9 and interface 13, constantly import CPU12, provide the distribution of grain size in the suspending liquid after handling by it.The resulting granules size distribution is presented on the display unit 17.In addition, the present invention also is designed to be able to be used for the situation that gravity field replaces centrifugal force field.In such cases, yes at sampling receptacle 1 is maintained fixed under the motionless condition and measures.Measuring the program of using with gravity field also is stored in the read-only memory 11.
Referring to Fig. 7, the method for utilizing this device for carrying out said to measure particle size distribution is described below, the process flow diagram that Fig. 7 represents has been represented the program that is stored in the read-only memory 11.
Before measurement, measuring condition is to determine by the data of input, for example, and the granular mass density P of size distribution to be measured
pAnd this particle constitutes the liquid medium density P of suspending liquid together
1The viscosity η of this medium, suspending liquid (time per unit) rotation number N appears at the distance R i(i=1,2,3 in formula (2) and (3)), also placed zero spacing in addition.After having done above-mentioned preparation, with the suspending liquid sampling receptacle 1 of packing into.
Carry out at an operational order according to keyboard 16 under the situation of gravity field measurement, photodetector 5(motor 3 keeps not rotating), detect light absorption continuously by suspending liquid.Detected light absorption is write continuously by random access memory (RAM) 15.When the absorption of light reached a certain predetermined value, microprocessor 12 utilized the data in the random access memory (RAM) 15, according to being used for the flow process that gravity field data is handled, calculated particle size distribution in the suspending liquid.The particle size distribution that obtains is presented on the display unit 17.Under situation about measuring with centrifugal force field, motor 3 begins to rotate constantly writes from the continuous data about the absorption of suspending liquid light of output of photodetector 5 suspending liquid rotation, random access memory (RAM) 15.When light absorption reached a certain predetermined value, motor 3 stopped operating, then to just be input to the P of this device when beginning
p, and P
1Numerical value compares, if Pp is less than P
1Judge that so this movement of particles entad is.In this kind situation, the time t that surveys light absorption is transformed into particle diameter D with formula (2)
p, and obtain carrying out corrected particle size distribution to assembling movement of particles according to formula (4), and be presented on the display unit 17.On the other hand, if P
pGreater than P
1, judge that so movement of particles is centrifugal, with formula (3) and formula (5) count particles size distribution.
In above embodiment, to P
pAnd P
1Relatively finishing automatically of numerical value by this device.Yet also can design a kind of device, can manually be input in this device a functional symbol and finish this comparison.In addition, be stored in formula (4) and formula (5) in the read-only memory 11, can replace with the corrected parameter that calculates under certain condition in advance by these formula.The light source that detects suspension particle concentration is not limited to visible light, also can be X ray.
Know easily that from above description the present invention can revise because the non-parallel kinetic influence of particle in the suspending liquid in centrifugal force field.This correction is included in the centrifugal force field, acts on making a concerted effort on the particle and be two kinds of centripetal force and centrifugal force.Therefore, do not have in the particle size distribution of measurement because the error that non-parallel movement of particles is brought apparent granule density influence.
Claims (2)
1, a kind of measurement mechanism of particle size distribution, the particle suspending of the particle size distribution that handle will be measured in this equipment is in a kind of suspending liquid, suspending liquid places centrifugal force field, above-mentioned particle is moved in suspending liquid, change by the local concentration that detects particle relevant in the said suspending liquid and measure particle size distribution with the time; Described device comprises a kind of memory, is used for storage;
First program is used to proofread and correct by said particle is non-parallel and entad moves to the influence of apparent granule density;
Second program is used to proofread and correct by the influence of the non-parallel centrifugal motion of said particle to apparent granule density, and design or can selectively carry out above-mentioned first or above-mentioned second program.
2,, be numerical relation wherein, and when the measuring condition data are input in the device, finish automatically by installing according to particle density and suspension medium density to the selection of above-mentioned first and second program according to claim 1 described device.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 85104282 CN1010978B (en) | 1985-06-06 | 1985-06-06 | Particle size distribution measuring device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 85104282 CN1010978B (en) | 1985-06-06 | 1985-06-06 | Particle size distribution measuring device |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN85104282A true CN85104282A (en) | 1986-12-03 |
| CN1010978B CN1010978B (en) | 1990-12-26 |
Family
ID=4793746
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN 85104282 Expired CN1010978B (en) | 1985-06-06 | 1985-06-06 | Particle size distribution measuring device |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN1010978B (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1330961C (en) * | 1997-11-28 | 2007-08-08 | 米什兰集团总公司 | Reinforcing aluminium filler and rubber composition containing same |
| CN1924554B (en) * | 2005-08-29 | 2010-09-08 | 株式会社堀场制作所 | Particle size distribution analyzer |
| CN105784551A (en) * | 2014-12-15 | 2016-07-20 | 夏普株式会社 | Method and sensor for detecting concentration of micro particles |
| CN114062208A (en) * | 2021-11-18 | 2022-02-18 | 上海新亚药业闵行有限公司 | Method for analyzing particle size of cefalexin |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101968431B (en) * | 2010-09-15 | 2012-07-25 | 苏州尚科洁净技术有限公司 | Vacuum state cleanliness hierarchy test method of the vacuum state cleanliness hierarchy test system |
-
1985
- 1985-06-06 CN CN 85104282 patent/CN1010978B/en not_active Expired
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1330961C (en) * | 1997-11-28 | 2007-08-08 | 米什兰集团总公司 | Reinforcing aluminium filler and rubber composition containing same |
| CN1924554B (en) * | 2005-08-29 | 2010-09-08 | 株式会社堀场制作所 | Particle size distribution analyzer |
| CN105784551A (en) * | 2014-12-15 | 2016-07-20 | 夏普株式会社 | Method and sensor for detecting concentration of micro particles |
| CN114062208A (en) * | 2021-11-18 | 2022-02-18 | 上海新亚药业闵行有限公司 | Method for analyzing particle size of cefalexin |
Also Published As
| Publication number | Publication date |
|---|---|
| CN1010978B (en) | 1990-12-26 |
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