FI20217174A1

FI20217174A1 - Measuring method and arrangement

Info

Publication number: FI20217174A1
Application number: FI20217174A
Authority: FI
Inventors: Tommi Niskanen; Ismo Joensuu; Tuomo Aho
Original assignee: Valmet Automation Oy
Priority date: 2021-11-12
Filing date: 2021-11-12
Publication date: 2023-05-13
Also published as: DE102022129850A1; SE2251304A1; CA3181606A1

Abstract

The invention describes a method of measuring processed (200) textile waste, by receiving (202) a suspension sample, comprising at least a first component of natural fibres and a second component of non-organic fibres, diluting (204) the suspension sample until a given consistency has been reached, directing the suspension sample to a measurement chamber, directing optical radiation at the suspension in the measurement chamber, capturing (206) at least one measurement image of the suspension and detecting (208) natural fibres and non-organic fibres of the suspension sample. Further determining (210) by a data processing sub-unit the amount of different components in the sample.

Description

MEASURING METHOD AND ARRANGEMENT

Technical Field

The exemplary and non-limiting embodiments of the invention relate generally to measuring properties of a suspension in a textile waste processing system.

Background

The following description of background art may include insights, discoveries, understandings or disclosures, or associations together with disclosures not known to the relevant art prior to the present invention but provided by the invention. Some of such contributions of the invention may be specifically pointed out below, whereas other such contributions of the invention will be apparent from their context.

Due to increased interest in environment, recycling of all kinds of materials has increased. Reuse of textile waste is a topic under research. In textile — recycling, fibres, yarns or fabrics are recovered and reprocessed to have a form in which they can be used for providing new products. One problem associated with processing textile waste is that textiles are composed of many kinds of different materials. For example, properties of natural and non-organic fibres are different and prior reuse the separation of the different materials is advantageous. To be able to process textile waste reliable and efficient measurement solutions are needed.

Brief description

N An object of the invention is to provide an improved method and an

N 25 arrangement implementing the method to reduce or avoid the above-mentioned = problems.

N The objects of the invention are achieved by methods as claimed in

I claim 1 and 7, by arrangement as claimed in claim 8.

E Some embodiments of the invention are disclosed in the dependent = 30 claims. =

O Brief description of the drawings

In the following the invention will be described in greater detail by means of preferred embodiments with reference to the accompanying drawings, in which

Figure 1 illustrates an example of an arrangement for processing recycled textile waste;

Figure 2 is a flowchart illustrating an example of an embodiment;

Figure 3 illustrates a measurement device; and

Figures 4A and 4B illustrate examples of the measurement chamber; and

Figure 5A and 5B are exemplary measurement images of the suspension.

Detailed description of some embodiments

The solution according to the invention is suitable for measuring — processing of textile waste or textile pulp. In the processing of textile waste or pulp the purpose in general is to separate components of different types so that the waste may be recycled and reused. Typically, the purpose is to separate non- organic and natural materials from each other. For example, if organic or natural fibres may be recovered from the textile waste or pulp, they may be reused, thus reducing for example in a textile manufacturing a need for new natural fibres, such as cotton fibres, the production of which requires a lot of natural re-sources, for example a lot of clean water.

Fig. 1 illustrate an example of an arrangement for processing recycled textile waste or pulp, where embodiments of the invention may be utilized. It may : 25 be noted that the illustrated arrangement is provided as an example of a possible

N realization of a processing eguipment and that the proposed measurement method

N and apparatus may be utilized also in different arrangements where textile waste

T or pulp is processed. = In the illustrated arrangement, recycled textile pulp is manufactured by z 30 mixing the textile waste and water (or other suitable liquid) and by slushing the 3 mixture to form the recycled textile pulp. Some additives may be added to the ~ mixture to improve the slushing of the mixture and/or a further processing of the

N recycled textile pulp. Different alternatives for the manufacturing of the recycled

N textile pulp are generally obvious for a person skilled in the art and are not disclosed herein in more detail.

In the process of Fig. 1, the textile waste or pulp is stored in a storage 100 prior processing. Prior storing the waste in the storage 100, the waste may be preprocessed for example in some mechanical or chemical manner.

The processing of textile waste typically comprises a number of different phases or stages where the waste is processed in various manner, both mechanically and chemically. The number and nature of stages may depend on the type or intended use of the waste to be processed. In this example arrangement, — the textile waste is taken from the storage and taken to dispersing stage 102 for dispersing or deflaking the recycled textile phase. The dispersing stage 102 may comprise at least one dispergator. In the dispergators, the textile waste is processed mechanically by tearing large textile material pieces into smaller pieces, preferably to fibres and/or fiber blocks suitable for refining. The dispersing stage 102 may be unnecessary if there are no large textile material pieces in the textile waste.

Water or some other liquid may be added to the textile waste. In the event of the consistency of the recycled textile pulp being too high for the dispersing stage 102 to operate properly, dilution water some other liquid 104 may be added into the pulp for decreasing the consistency thereof.

From the dispersing stage 102 the textile waste is taken to refining stage 106. The refining stage 106 comprises at least one refiner. A fibrillation and fiber cutting of the recycled textile fibres is provided at the refining stage 20.

The recycled textile waste may be fed into the refining stage 106 in a substantially low consistency, typically in a consistency of about 1% to 5%. Due to : the substantially low-consistency of the textile waste, the at least one refiner is

N preferably selected or configured to be a low-consistency refiner, i.e. a refiner = especially configured to refine the textile waste of low-consistency. In the event of

Tr the consistency of the textile waste being substantially higher than 10% for high = 30 consistency refining or 5% for low consistency refining, or for otherwise z controlling the operation of the refining stage 106 and especially the operation of

NI the at least one refiner therein, the textile waste to be fed into the at least one

N refiner may be diluted with dilution water or some other liguid 108 to decrease the

N consistency of the textile waste.

N 35 From the refining stage 106 the textile waste is taken to bleaching stage 109. In bleaching, the textile waste is processed, typically using suitable chemicals,

to remove colour of the materials. The chemicals may be selected based on the properties of the textile waste. For example, oxidation, where colour is removed by the application of oxygen, or reduction, where colour is removed by hydrogenation, may be used. In addition, heated alkaline hydrogen peroxide may be applied. As before, water or some other liquid 110 may be added to the textile waste.

From the bleaching stage 109 the textile waste is taken to screening stage 112. The screening stage 112 comprises at least one screening device. In the screening state 112 the textile waste is sorted based on the fibre size. The screening device may for example be a pressure screen, a bow screen or a cleaner.

In some arrangements, the textile waste may be divided in the screening stage 112 into at least one accept fraction 114 of the textile waste and at least one reject fraction 116 of the textile waste. The screening stage 112 may provide a controlled fibre size distribution in the atleast one accept fraction 114. The atleast one accept fraction 114 of the screening stage 112 may be supplied out of the arrangement to a further treatment process (not shown). The at least one accept fraction 114 thus forming an outflow of the recovered processed recycled textile fibres, i.e. refined and screened textile fibres, from the arrangement. The further treatment process may for example comprise drying of these processed recycled textile fibres for textile industry, or a manufacturing of a dissolved pulp comprising also fibres of wood origin.

The at least one reject fraction 116 of the screening stage 112, that comprises for example long fibres, fibre bundles, fines and other particles such as synthetic fibres, is supplied to further processing to flotation stage 118.

In the event of the consistency of the refined textile pulp being too high for the screening stage 12 to operate properly, dilution water or some other liquid : 130 may be added into the pulp for decreasing the consistency there of.

S In the flotation stage 118, the textile waste is processed, typically using

At suitable liquids or gases, to separate natural and non-organic components from

Tr each other. All of the material that is not used in further processes are floated on = 30 — the surface and the rest of the suspension continues typically from the bottom of z the flotation container. The pH of the flotation stage can be used to control the

NI flotation. The pH over 7 is to be avoided. Examples for suitable liguids for flotation

N are flocculants and coagulants.

N The process continues with a washing stage 120 for washing the textile

N 35 — waste. The washing stage 120 comprises at least one washing device. In the washing stage 120 the remaining fibres may be separated from other material. The separated fibres are typically long fibres and fibre bundles, and the remaining other material are typically fines and other particles such as synthetic fibres.

In some arrangements, some output 122 of the washing stage 120 is supplied back to the refining stage 106 for further refining and some output 124 is 5 supplied forward towards a fines removal stage 126.

The fines removal stage 126 comprises atleast one fines removal device such as a centrifugal cleaning device for removing fines and possible other reject material, such as synthetic fibres.

Dilution water or some other liquid 128, 130, 132 may be added into — the waste at various parts of the process.

The arrangement of Fig. 1 may also comprise atleast one control system 134 configured to control the operations of the different stages and devices therein.

The arrangement of Fig. 1 comprises measurement apparatuses 136A, 136B, 136C, 136D, 136F, 136F at various parts of the process. The measurement apparatuses 136A — 136F may be connected to the control system 134 via control connections 138 which may be wired or wireless.

The measurement apparatuses 136A - 136F may perform measurements on the textile waste at various phases on the arrangement. The locations of the measurement apparatuses illustrated in Fig. 1 are merely examples. The locations of the measurement apparatuses may be selected based on current need, type of textile waste or on other reasons.

The control system 134 may comprise at least one processor and at least one memory device including computer program code, the at least one memory device and the computer program code configured to, with the atleast one — processor, cause the at least one control system 134 the control the operation of : the arrangement, such as the operation of the stages and mixing of the dilution

N water into the textile pulp, based for example on variables measured by = measurement apparatuses 136A - 136F. The control system 134 may control the

Tr various parts of the arrangement using control connections which maybe wired or = 30 — wireless. For clarity, the control connections are not shown in Fig.1 z The operation of the at least one dispergator in dispersing phase 102

NI may for example be controlled by adjusting a filling of a gap remaining between

N opposite dispergator elements in the dispergator, and/or by controlling the

N consistency of the textile pulp to be fed into the dispersing stage 102.

N 35 The operation of the at least one refiner in the refining phase 106 may for example be controlled by adjusting a refining degree or a specific energy consumption in the at least one refiner, and/or by controlling the consistency of the textile pulp to be refined.

The operation of the atleast one screening device in the screening phase 112 may for example be controlled by changing a reject ratio or an operating power ofthe screening device, such as a rotation frequency of a rotor of a screening device, and/or by controlling the consistency of the textile pulp to be fed into the screening stage 112.

The operation of the at least one washing device in the washing phase 120 may be controlled by controlling for example a rotational frequency, inlet pressure, pressure difference, feed consistency and/or reject rate in the atleast one washing device.

The operation of the at least one centrifugal cleaning device in fines removal 126 may for example be controlled by changing an operating power of the centrifugal cleaning device, such as a rotational frequency of the centrifugal — cleaning device.

In an embodiment, the arrangement of Fig.1 comprises a processing and measuring arrangements 140A, 140B in connection with screening stage 112 and flotation stage 118. In screening stage and flotation stage the ratio of the first and the second components, i.e. the ratio of natural fibres and non-organic fibres changes as a result of the processing. Here an arrangement comprising the processing stage and a measuring stage may be utilized

Fig.2 illustrates an example of a processing and measuring method. Fig. 3 illustrates an example of a processing and measuring arrangement. In an embodiment, the processing and measuring arrangement comprises a processing — stage 300 and a measuring stage 302. : In step 200, textile waste comprising at least a first component of

N natural fibres and a second component of non-organic fibres is processed in a = processing stage 300 where the ratio of the first and the second components

Tr changes as a result of the processing. In an embodiment, the processing stage is the = 30 screening stage 112. In an embodiment, the processing stage 300 is the flotation z stage 118. The processing stage 300 comprises input 304 from a previous stage

N and output 306 to a further stage.

N In step 202, the arrangement comprises a sample line 308 configured to

N receive a suspension sample, the sample comprising at least a first component of

N 35 natural fibres and a second component of non-organic fibres. The sample may be obtained from the output 306 of the processing stage 300, for example. The sample may be obtained also from the processing stage 300 itself. The sample line forwards the sample into the measuring stage 302, especially into a mixing chamber 310 of the measuring stage of the arrangement. The process of obtaining the sample from the suspension of the processing stage is as such well known to one skilled in the art. Depending on process pressure different sequences may be needed for taking the sample. For example, if the process pressure is less than atmospheric pressure, a piston or a special valve and pipeline arrangement may be needed for sampling the process to prevent water used as sample moving liquid to get into the process container.

In an embodiment, the suspension sample comprises textile waste. In an embodiment, the suspension sample comprises textile waste and wood fibres.

In step 204, the apparatus is configured to dilute the suspension sample until a given consistency has been reached. The given consistency may be reach by adding a certain amount of water or other liquid to a known amount of suspension sample.

The arrangement is configured to mix the suspension sample for a predetermined time period. The mixing time may be an adjustable parameter. For example, the time period may be around 10 seconds. The time period may also be much shorter if proper way of mixing is used. At the end of mixing a given consistency has been reached. In an embodiment, air or suitable liquid 316 may be added to the suspension in the mixing phase. The suitable liguid may be water or solvent based liguid.

The mixing chamber 310 may comprise a mixing input 318, which enables controlling the mixing of the material in the chamber. The chamber may comprise suitable means for mixing the material in the chamber. These means are : known to one skilled in the art.

N In addition, the temperature of the suspension may be adjusted. The = mixing chamber may comprise temperature control input 320 and appropriate

Tr temperature adjustment unit 322 such as a heater and/or a cooler. = 30 In an embodiment, chemical is added to mixing chamber 310 for z enhancing the vertical separation of natural and non-organic fibres. One way is to

NI increase the density of the suspension so that the natura] fibres, that has lower

N density compared to non-organic fibres, can be directed to the top part of the

N suspension and the non-organic fibres to the bottom of the suspension. E.g., acetic

N 35 acid may be added. When different mix of fibres is measured the vertical separation may also done so that the non-organic fibres may stay afloat, and the organic fibres may end up to the bottom. E.g., ethanol as less dense liquid may be used to lower the suspension total density. Also adding air bubbles to the suspension can provide the same affect. One way increase vertical separation of natural and non-organic fibres is to add chemical that attach lighter molecules with natural fibres and thus increase buoyancy of the natural fibres. It may be also possible to add chemical that decrease the buoyancy of the natural fibres and thus affect the opposite. The outlet from the mixing chamber may be from the bottom of the mixing chamber. This way the fibres can be pumped out from the mixing chamber so that vertically separated different components come one after each other out from the mixing chamber. A predetermined time is needed to settle the suspension. The time may be 30 sec - 10 min.

The apparatus comprises a feed 328 connecting the mixing chamber 310 and the measurement chamber 324. The feed may comprise a pump intended to move the suspension forward. In an embodiment, the feed may comprise a tube fractionator where components of different sizes may be separated from each other. After the mixing is done, the mixed suspension sample is directed to the measurement chamber. The suspension sample may be fractioned by the fractionator while moving from mixing chamber to measurement chamber;

Optical radiation from light sources 408, 410 is directed into the measurement chamber 324 illuminating the suspension sample.

In step 206 a measurement image is captured of the suspension illuminated by the optical radiation with an image capturing device 406.

In step 208, the natural fibres and non-organic fibres are detected from the captured image on the basis of pattern recognition applied to the image.

In step 210, the apparatus is configured to determine the amount of one : or more different components in the sample based on the detection.

N In an embodiment, the temperature of the suspension in the = measurement chamber may be adjusted. The measurement chamber may

Tr comprise temperature control input 332. The measurement chamber may = 30 comprise an appropriate temperature adjustment unit 334 such as a heater and/or z a cooler.

NI In an embodiment air or suitable liguid may be added to the suspension

N sample at various phases 330 of the process. Further, the air or suitable liguid may

N be used to flush the measurement chamber between different samples. The

N 35 suitable liquid depends on the pH of the sample. For example, if the liquid is acidic the used flushing chemical can be NaOH or KOH and if the liquid is alcalic the flushing chemical can be citric acid.

In an embodiment, the apparatus may comprise a controller controlling the operation of the apparatus. Control connections are not illustrated in Fig. 3 for clarity. The control or partial control of the apparatus may also be performed externally from a controller external to the apparatus but operationally connected to the apparatus.

The apparatus may also comprise other components such as valves and pumps, for example.

Figs. 4A and 4B illustrate examples of the measurement chamber 324.

Let us first study the example of Fig. 4A. The suspension sample 400 comprising textile waste is provided to the measurement chamber. The measurement chamber may have windows 402, 404 at the opposite sides of the chamber. An image capturing device 406 such as digital camera or other digital photographic device is located at one side of the chamber behind the window 404. Source of optical radiation or light source 408, 410 are located on either side of the chamber behind the window 402, 404. The sources 408, 410 may be Light Emitting Diodes, LEDs, for example. The LED’s may provide wide bandwidth light or only given wavelength(s).

In an embodiment, there are filters 412, 414 in front of the light sources 408, 410 and/or a filter 416 in front of the image capturing device 406. The filters may pass through a given wavelength or wavelength range. There may also be separate light sources for all required wavelength ranges.

In an embodiment, the optical radiation from the source 410 on the — opposite side of the image capturing device 406 passes through the suspension : sample to the image capturing device. The image capturing device captures an

N image in which outlines of the components in the suspension are visible and thus = the details of the components may be determined.

N In another embodiment, the optical radiation from the source 408 on = 30 — the same side as the image capturing device 406. The fibres in the suspension are z lighted and an image with details of the fibres visible is possible to be taken from

NI the suspension.

N In an embodiment, the wavelength of the optical radiation has a range

N of 400 to 800 nm and a suitable filter may be applied in front of the image capturing

N 35 device. The optical radiation source may also be in shorter wavelengths to detect the fibrils better. E.g. optical radiation range may be in ultra violet range such as

315 to 400 nm. Naturally the image capturing device must be able to detect the used range. The wavelength of the optical radiation may be limited by using a narrow band light source or applying a suitable filter in front of the source.

The image taken by the image capturing device is passed to image processing sub-unit for detecting the natural and non-organic fibres from the image. The detecting may be done on the basis of pattern recognition applied to the captured image. The pattern recognition algorithm is configured to look for lengthy particles within the image. Any suitable algorithm e.g. feature extraction, frequentist approach or Bayesian statistics may be used.

In one embodiment the detection of the natural and non-organic fibres is based on the state of fibrillation that can also be described as fibrillation index.

The state of fibrillation provides at least one comparable number among different analysed images. This number relates to the amount of connected fibrils in the image. Fibrillation index that represents amount of thin thread like matter attached — to fiber. Fibrillation index for a fiber region can be defined as ratio of projection area of fibrillation and projection area of whole fiber region, scaled to percent.

Projection area of whole fiber region can be calculated by integrating opacity over region. Inverse distance transformation starting from fiber skeleton may be used to mask the fiber body. Projection area of fibrillation is calculated by subtracting total fiber area from region's area. The fibrillation index for a region is area of fibrillation multiplied with coefficient and divided by total region area. The bigger fibrillation index the bigger portion of natural componentis in the suspension.

The state of fibrillation may also be defined using other comparable fibrillation related value. The following list is an exemplary compilation of values —thatmaybe used: average fibrillation index, fibrillation distribution by fiber length : and/or width, percentage of fibrillated fibres and not-fibrillated fibres of measured

N fibres, number of fibrillated fibres and not-fibrillated fibres of measured fibres, and = fibrillation of measured fibres. The state of fibrillation may also be defined by

Tr calculating two or more aforementioned values together. = 30 In another embodiment the detection of the natural and non-organic z fibres is based on the thickness of the fibres. The non-organic fibres 501 - 503 may

NI be detected by their static thickness throughout the whole length of the fibre. The

N natural fibres 504 - 506 have thinner ends 507 than middle part 508 of the fibre.

N Comparing the thickness of the fibre may be done in several location in the center

N 35 = area and thus it is possible to get an average center thickness. The thickness in the end of the fibre may be measured e.g. when there is 10%, 5% or 3% of the fibre length to the end. The measurement can be done in several points to find out if the thickness is decreasing from the center to the end. If the fibre has been cut during process, the non-organic fibre may only have one thin end.

Fig. 5A and 5B is exemplary measurement image of the suspension. The non-organic fibres 501 - 503 can be seen as smooth and equally thick. The variation with natural fibres 504 - 506 is larger. Small fibrils can be seen attached to the some of the natural fibres 504, 505. The thickness within single non-organic fibre also varies between the center 508 of the fibre and one or both ends 507 of the fibre.

The image processing sub-unit provides the amount of natural fibres and non-organic fibres of the suspension sample to the data processing sub-unit that may further calculate the amount of different components within the sample.

Additional information may be used for the calculation such as calibration coefficient that is obtained using laboratory measurements for the samples.

Additional measurements may be used to enhance the calculation accuracy and stability. For example, the image can be taken multiple times and combine the detection results. Additionally, the sample may be fractioned, and image may be taken from different fractions.

Based on above it is possible to determine the amount of one or more different components in the suspension sample.

Let us next look at the example of Fig. 4B. The suspension sample 400 comprising textile waste is provided to the measurement chamber. The measurement chamber may have windows 402, 404 at the opposite sides of the chamber. An image capturing device 406 is located at one side of the chamber — behind the window 404. Source of optical radiation or light source 408 is located : on the same side ofthe chamber behind the window 404. There is a diffuse reflector

N 420 on the opposite side of the chamber behind the window 402. = In an embodiment, the optical radiation from the source 410 may reflect

Tr from the reflector 420 to the image capturing device 406, passing through the = 30 — suspension sample. The image capturing device captures an image in which z outlines of the components in the suspension are visible and thus the details of the

NI components may be detected. ~ In another embodiment, the optical radiation from the source 408 on

N the same side as the image capturing device 406. The fibres in the suspension are

N 35 lighted and an image with details of the fibres visible is possible to be taken from the suspension.

The image processing sub-unit and data processing sub-unit may be common processors, field programmable gate array (FPGA) or application specific integrated circuit (ASIC). The image processing sub-unit and data processing sub- unit may be located directly attached to the image capturing device 406 or they may be connected using network or other data-communication means to each other. The image processing sub-unit and data processing sub-unit may be integrated into one physical processor or board.

An embodiment provides an arrangement for processing and measuring textile waste, the arrangement comprising means for processing the textile waste comprising at least a first component of natural fibres and a second component of non-organic fibres where the ratio of the first and the second components changes as a result of the processing; means for receiving a suspension sample from the output of the processing stage; means for mixing the suspension sample for a predetermined period; means for directing the suspension sample to a measurement chamber; means for directing optical radiation at the suspension in the measurement chamber; means for capturing an image of the suspension; means for processing the image for detecting the natural fibres and non-organic fibres of the suspension sample and means for determining the amount of different components in the suspension sample based on the detection.

It will be obvious to a person skilled in the art that, as the technology advances, the inventive concept can be implemented in various ways. The invention and its embodiments are not limited to the examples described above but may vary within the scope of the claims.

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Claims

1. A method of measuring textile waste, the method comprising: receiving (202) a suspension sample, the sample comprising at least a first component of natural fibres and a second component of non- organic fibres; diluting (204) the suspension sample until a given consistency has been reached; directing the suspension sample to a measurement chamber; directing optical radiation at the suspension in the measurement chamber; capturing (206) at least one measurement image of the suspension illuminated by the optical radiation with an image capturing device; receiving the at least one measurement image and detecting (208), by an image processing sub-unit natural fibres and non-organic fibres of the suspension sample and determining (210) by a data processing sub-unit based on the detected natural and non-organic fibres the amount of different components in the sample.

2. The method of claim 1, further comprising: fractioning the suspension sample into components of different sizes while directing into measurement chamber.

3. The method as claimed in any preceding claim, further comprising: detecting the natural fibres and non-organic fibres by fibrillation of _ fibres on the basis of pattern recognition applied to the captured image. S

-

4. The method of claim 1 or 2, further comprising: A, detecting the natural fibres and non-organic fibres by thickness changes = 30 of single fibres on the basis of pattern recognition applied to the E captured image. N n

5. The method as claimed in any preceding claim: O determining the amount of different component in the sample by applying the detected amount of natural fibres and non-organic fibres with calibration coefficient.

6. The method as claimed in any preceding claim: Adding chemical to mixing chamber for enhancing the vertical separation of natural and non-organic fibres.

7. A method of controlling a multi-phase processing of suspension of recycled textile waste comprising at least a first component of natural fibres and a second component of non-organic fibres, the method comprising: measuring the amount of different components in the suspension at one or more different phases of the processing utilising the method of any preceding claim 1 to 6 and controlling the processing on the basis of the measurements.

8. An arrangement for processing measuring textile waste, the arrangement comprising: a processing stage (300) processing the textile waste comprising at least a first component of natural fibres and a second component of non-organic fibres where the ratio of the first and second components changes as a result of the processing; a sample line (308) for receiving a suspension sample from the output of the processing stage; characterized by a mixing chamber (310) for mixing the suspension sample until a given consistency has been reached; a feed (328) for directing the suspension sample to a measurement : chamber (324); N a source (408, 410) directing optical radiation at the suspension in the = measurement chamber; Tr an image capturing device (406) for capturing at least one = 30 measurement image of the suspension z an image processing sub-unit for detecting, natural fibres and non- NI organic fibres of the suspension and N a data processing sub-unit for determining the amount of different 3 components in the sample based on the detected fibres.

9. The arrangement as claimed in claim 8, wherein a feed 328 connecting the mixing chamber 310 and the measurement chamber 324 comprise a fractionator where components of different sizes are separated from each other.

10. The arrangement as claimed in any preceding claim 8 to 9, wherein the image processing sub-unit detects the natural fibres and non- organic fibres by the fibrillation of fibres or by the thickness changes of single fibres on the basis of pattern recognition applied to the captured image. N O N N I Ac a + K ~ N O N