AU669034B2 - Apparatus for measuring material - Google Patents

Description

669034

AUSTRALIA

Patents Act 1990 COMPLETE SPECIFICATION STANDARD PATENT Applicant: OUTOKUMPU MINTEC OY Invention Title: APPARATUS FOR MEASURING MATERIAL act' The following statement is a full description of this invention, including the best method of performing it known to me/us: r- CI- -JC 1

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i APPARATUS FOR MEASURING MATERIAL SThe present invention relates to an apparatus for measuring solid particle size distribution in a flowing material, when the employed flowing medium is liquid and/or gas.

From the FI patent application 903,351 there is known a mass particle size distribution device, where the mass i particle size detector is located in a measuring chute, wherethrough the mass under measurement is made to flow when the granulometric composition is being measured, and which measuring chute is connected to an auxiliary chute wherethrough the mass flow passes, when the measuring chute is being washed. The apparatus also includes a mass feeding :i15 pipe connected to a member for guiding the mass flow from the measuring chute to the auxiliary chute. In this mass t flow guide member, there is movably installed a chamber, ritr and the chamber is divided into two parts by means of an actuator provided in the chamber, so that one of the parts is connected to the washing water feed pipe feeding water to the measuring chute. The actuator is also connected to the mass feed pipe by means of a spring-loaded rod in order to guide the mass flow iR between the measuring chute and the auxiliary chute. When the mass particle size 25 detector located in the measuring chute should be washed, tat.

the valve of the washing water feed pipe is opened. Now the pressure caused by the washing water is directed to the mass flow guide member, too, so that instead of the nmeasuring chute, the mass flow is conducted to the auxiliary chute. In order to stop the washing of the mass particle size detector, the valve of the washing water feed pipe is closed, and owing to the pressure change, the mass flow guide member again guides the mass flow to the measuring chute.

9 2 According to the said Finish patent application 903,351, the same mass flow particle size detector is used for both coarse and fine particles, which means that the detector is easily susceptible to mechanical wear. Likewise, the measuring accuracy of the apparatus is reduced by the fact that the same detector is used for materials with different solid contents.

The object of the present invention is to attempt to eliminate some of the drawbacks of the prior art.

According to the present invention there is provided an apparatus for measuring particle size distribution in flowing material containing solids, said apparatus having a material feeding conduit having a turnable feeding discharge nozzle, said discharge nozzle being able to be turned to discharge to either a measuring channel or a bypass channel, said measuring channel having a measuring element therein composed of two opposed measuring surfaces, one of which is arranged to be movable towards and away from the other; said opposed measuring surfaces being 20 disposed so the discharged flowing material passes I therebetween, the apparatus having a particle size distribution measurement registering device associated with said two opposed measuring surfaces for measuring the 2 particle size distribution of solids between the opposed 25 measuring surfaces; said apparatus having a cleaning medium conduit for passage of a cleaning medium for cleaning the measuring surfaces and wherein the measuring area of the "'ameasuring surfaces of the measuring element is chosen to suit the solid content of the flowing material.

S 30 In the example of the preferred embodiment, the material under measurement is conducted, through a feed pipe, into a measuring channel, where a measuring element required for defining the particle size of the material is installed.

The measuring element is composed of two measuring IL9 Ca0 Nnr4Lj ~1 -r -3surfaces, one of which remains stationary and the other moves according to a micrometer principle back and forth in relation to the stationary measuring surface. Part of the material flowing in the measuring channel passes between the surfaces of the measuring element. The particle size values obtained from the measuring surfaces are electrically transferred to a registering device, which further translates the obtained values to particle size distribution.

The measuring area of the measuring surfaces contained in the measuring channel advantageously depend on the solid content of the material under treatment. With different solid content, different amounts of measured particles remain between the measuring surfaces, and consequently a random sample to be used in the definition of the particle size distribution will change depending on the solid content. The measuring area o: the measuring element used in the measurement of particle size distribution is advantageously maintained such that irrespective of the solid content, the random sample obtained on the measuring element and used for defining the particle size "distribution will be essentially equal in volume. The size of the random sample can advantageously be affected by means of the ratio of the measuring area and the solid 25 content. The ratio of the measuring area and the solid content is within the region 0.008 0.5, advantageously 0.015 0.025, when the employed unit is a square centimetre per percent solids. The solid content for the material used in the example of the preferred apparatus can fluctuate from 1 to 60 percent.

6' esm The registering device can be put in operation so that the cc ~registering device, also gives as a result one or more parameters representing the particle size distribution of the material to be measured. Such parameters are for instance the mass fraction of one predetermined particle i i I i -4size class or the particle size of one predetermined mass fraction. The determination of these parameters are based on the average and the standard deviation of the consecutive measurements accounted in the registering device. The parameters based on the measurements are advantageously reliable because when utilizing the ratio of the measuring area and the solid content the fluctuations of the solid content can be compensated by the parameters of the particle size distribution.

The example of the apparatus can be applied for flowing material, when the flowing medium is a liquid or a gas or a combination thereof. The material to be measured can be some slurry-like material, where the flowing medium is a liquid, usually water. In addition to this, the apparatus can be used for measuring solid substance that are fluidized for instance by a gas, such as air.

During the particle size distribution measurements, on the measuring surfaces there may remain residues of the particles under measurement, which residues may cause degradation of the measuring accuracy of the apparatus.

The cleaning of the measuring surfaces of possible particle r residues can advantageously be carried out with a cleaning 25 medium, which can be a liquid, such as water, or a gas, such as air. Advantageously the cleaning medium is liquid 25 if the flowing medium is liquid. Likewise, when the flowing medium is gas, the employed cleaning medium ,_:advantageously is gas, too. In order to carry out the cleaning, the material under measurement is conducted, for Sthe duration of the cleaning, to pass by the measuring 30 channel via a separate by-pass channel. When the cleaning operation should start, the actuators used in the cleaning C are activated. Owing to the activation of the actuators, CcC the connected valve system shifts the material flow guide member so that the material flow is directed into the byiPi 5 pass channel instead of the measuring channel.

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5 Simultaneously the valve system opens the valve containing cleaning medium, and the cleaning medium starts to flow into the measuring channel. After the cleaning stage, the valve system first interrupts the flow of the cleaning medium, and thereafter shifts the material flow back into the measuring channel; now the operation of the apparatus is advantageously returned to the operational stage, i.e.

to the determination of particle size distribution.

In order that the invention may be more clearly ascertained an example of a preferred embodiment will now be described with reference to the appended drawing, which illustrates apparatus in partial cross-section, viewed from the side.

According to the illustration, the material under measurement is fed through the feeding conduit 1 to the feeding nozzle 2. The feeding nozzle 2 is turnably connected to the feeding conduit 1, and the feeding nozzle 2 is installed in the feeding chamber 3. When the apparatus is in operation in order to define the particle size of the material under measurement, the said material, such as a slurry flow, is conducted to a measuring channel 4 via the feeding nozzle 2. In the measuring channel 4, .set there is installed a measuring element 5, composed of two .054 measuring surfaces 6 and 7. One of the measuring surfaces, 6, is installed in a stationary fashion in the meesuring S! 25 channel 4. The second measuring surface 7 is connected to a motion element 8 located outside the measuring channel 4, which motion element 8 causes the measuring surface 7 to towards the second surface 6 and away therefrom at a desired frequency. Advantageously the measuring surfaces 6 and 7 are made of durable material, such as silicon carbide. Moreover, the measuring area of the measuring surfaces 6 and 7 advantageously is proportional to the solid content of the material under measurement.

In relation to each other, the measuring surfaces 6 and 7 iit 6 of the measuring element are advantageously operated according to a micrometer principle. The measuring surfaces 6 and 7 are advantageously located in the measuring channel 4 so that at least part of the solid particles contained in the flowing material under measurement passes between the measuring surfaces 6 and 7.

Now, when the measuring surface 7 moves back and forth in relation to the measuring surface 6, from the particle or particles remaining between the measuring surfaces 6 and 7, there is measured, according to the micrometer principle, the dimension essentially perpendicular to the measuring surfaces 6 and 7. The result is electrically transferred to the registering and processing device 16 provided in connection with the measuring device, so that the particle size distribution of the material under measurement can be defined as a combination of several different measuring results.

Because the measuring surfaces 6 and 7 are at least partly in physical contact with thesolid particles under measurement, there arises from time to time a need to clean the measuring surfaces 6 and 7 of the solid particle residues possibly remained thereto. In order to start the cleaning stage, the actuators required in the cleaning of the apparatus are activated. First, in order to change the o: 25 route of the material flow from the measuring channel 4 to Sthe by-pass channel 9, the position of the material feeding nozzle 2 is changed by using the guide member 10. The feeding nozzle 2 is connected, by means of a connecting eeuo member 11, to the guide member 10, and by means of compressed air which is conducted into the valves 12 and 13 provided in this guide member, the position of the feeding nozzle 2 is adjusted for the cleaning stage. The guide member 10 is further connected to a conduit 14, wherethrough the cleaning medium, such as water, is conducted to the measuring channel 4 and further onto the Imeasuring surfaces 6 and 7. When the position of the -7 feeding nozzle 2 is adjusted so that the material flow is conducted into the by-pass channel 9, a valve 15 connected to the conduit 14 is opened, and the cleaning medium flows freely onto the measuring surfaces 6 and 7. At the end of the cleaning stage, the valve 15 is closed and the feeding nozzle 2 is returned back to the position where the material flow can enter the measuring channel 4.

The above description illustrates the invention with reference to an example of one preferred embodiment only, but the invention can be largely modified within the scope of the appended patent claims.

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Claims (7)

1. 2. An apparatus according to claim 1, wherein the measuring area of the measuring surfaces is within the a a S' range 0.008 0.5 square centimetres per percent solids. S: 3. An apparatus according to claim 1 or 2, wherein the measuring area of the measuring surfaces is within the i 4 ;range 0.015 0.025 square centimetres per percent solids.
2. 4. An apparatus according to any one of the preceding claims, wherein the flowing material is a slurry.
3. 5. An apparatus according to claim 4, wherein the cleaning medium is a liquid.
4. 6. An apparatus according to any one of the claims 1 -9i~ti h.~II1 4 CT -;ll araa~l- l~ l~crra~ 9 3, wherein the flowing material is a fluidized solid substance.
5. 7. An apparatus according to claim 6, wherein the cleaning medium is a gas.
6. 8. An apparatus according to any one of the preceding claims, wherein the measurement registering device is used on the basis of the average and the standard deviation of consecutive measurements obtained by the measuring element for the parameters representing the particle size distribution of the material to be measured.
7. 9. An apparatus as claimed in any one of the preceding claims and substantially as herein described with reference to any one of the examples in the accompanying drawing. DATED THIS 18TH DAY OF JANUARY 1996 OUTOKUMPU MINTEC OY By Its Patent Attorneys: GRIFFITH HACK CO., Fellows Institute of Patent 20 Attorneys of Australia eo* 9 9* mpqi~- (57) ABSTRACT The invention relates to an apparatus for measuring par- ticle size distribution in solid matter from flowing material cortaining solids, in which apparatus a material feeding conduit is provided with a turnable feeding nozzle in order to feed the material, by.means of a guide member alternately to a measuring channel (4) or to a by-pass channel Moreover, in the measuring 0o0 channel of the apparatus, there is installed a measur- 10 ing element composed of two opposite measuring surfaces 0 0 0 D one of which is arranged to be movable. The appar- atus also comprises a measurement registering device (16) 0 0 0 0 and cleaning medium conduit (14) for cleaning the measuring surfaces According to the invention, the measuring area of the measuring surfaces 7) of the measuring element is dependent on the solid content of the flowing 0 0 o material, advantageously so that the area of the measuring o surfaces falls within the region 0.008 0.5 square centimeters per persent solids. a* e