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 organic 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

An object of the invention is to provide an improved method and an arrangement implementing the method to reduce or avoid the above-mentioned problems.

The objects of the invention are achieved by method of claim 1 and by apparatus as claimed in claim 10.

Some embodiments of the invention are disclosed in the dependent claims.

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 illustrates a measuring device;

Figure 3 illustrates an example of an arrangement for processing and measuring recycled textile waste; and

Figures 4A and 4B illustrate examples of a measuring chamber.

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, textile waste comprises at least a first component of organic fibres and a second component of non-organic fibres. Usually, the purpose is to separate the nonorganic and organic components 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 be noted that the illustrated arrangement is provided as an example of a possible realization of a processing equipment and that the proposed measurement method and apparatus may be utilized also in different arrangements where textile waste or pulp is processed.

In the illustrated arrangement, recycled textile pulp is manufactured by mixing the textile waste and water (or other suitable liquid) and by slushing the 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 recycled textile pulp. Different alternatives for the manufacturing of the recycled 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 fibre 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 fibre cutting of the recycled textile fibres is provided at the refining stage 106.

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 15%. Due to the substantially low-consistency of the textile waste, the at least one refiner is 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 the consistency of the textile waste being substantially higher than 10% for high consistency refining or 5% for low consistency refining, or for otherwise controlling the operation of the refining stage 106 and especially the operation of the at least one refiner therein, the textile waste to be fed into the at least one refiner may be diluted with dilution water or some other liquid 108 to decrease the consistency of the textile waste.

From the refining stage 106 the textile waste is taken to bleaching stage 106. 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 106 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 at least one accept fraction 114. The at least 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 128 may be added into the pulp for decreasing the consistency there of. In the flotation stage 118, the textile waste is processed, typically using suitable liquids or air, to separate organic and non-organic components from each other. All of the material that is not used in further processes are floated on the surface and the rest of the suspension continues typically from the bottom of the flotation container. The pH of the flotation stage can be used to control the flotation. The pH over 7 is to be avoided. Examples for suitable liquids for flotation are flocculants and coagulants.

The process continues with a washing stage 120 for washing the textile 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 supplied forward towards a fines removal stage 126.

The fines removal stage 126 comprises at least 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 at least 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, 136E, 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 at least 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 water into the textile pulp, based for example on variables measured by measurement apparatuses 136A - 136F. The control system 134 may control the various parts of the arrangement using control connections which maybe wires or wireless. For clarity, the control connections are not shown in Fig.l

The operation of the at least one dispergator in disperging phase 102 may for example be controlled by adjusting a filling of a gap remaining between opposite dispergator elements in the dispergator, and/or by controlling the consistency of the textile pulp to be fed into the dispersing stage 102.

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 at least one screening device in the screening phase 112 may for example be controlled by changing a reject ratio or an operating power of the 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 130 may be controlled by controlling for example a rotational frequency, inlet pressure, pressure difference, feed consistency and/or reject rate in the at least 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.l comprises a processing and measuring arrangements 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 organic 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 utilised.

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 organic 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 changes as a result of the processing. In an embodiment, the processing stage is the screening stage 112. In an embodiment, the processing stage 300 is the flotation stage 118. The processing stage 300 comprises input 304 from a previous stage and output 306 to a further stage.

In step 202, the arrangement comprises a sample line 308 configured to receive a suspension sample, the sample comprising at least a first component of organic 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 arrangement is configured to feed one or more colour components 312 to the sample. Colour components can be for example organic indigo for blue, carotenoid for yellow and non-organic malachite for green.

In an embodiment, the arrangement comprises or is operationally connected to a colour storage 314306 comprising one or more colour components which the colour storage may feed 312 into the mixing chamber 310. The colour storage 314 may comprise a pump or other suitable arrangement to feed the colour component(s) to the measurement chamber.

The colour storage may comprise a set of colour components. The one or more colours fed to the mixing chamber may be selected from the set of colour components in the colour storage. In an embodiment, the colour storage is filled prior the measurement process which suitable colour components.

The colour components may be organic, synthetic or combinations of both.

In step 206, 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. 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 liquid may be water or solvent based liquid. 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.

In addition, the temperature of the suspension may be adjusted. The mixing chamber may comprise temperature control input 320 and appropriate temperature adjustment unit 322 such as a heater and/or a cooler. In step 208, the arrangement is configured to direct the suspension sample to a measurement chamber 324 of the apparatus. The apparatus may comprise a pump 326 or other means for moving the suspension sample forward in the apparatus.

The arrangement comprises a feed 328 connecting the mixing chamber 310 and the measurement chamber 324. In an embodiment, the feed may comprise a fractionator where components of different sizes may be separated from each other.

In an embodiment, air or suitable liquid 330 may be added to the suspension sample at various phases of the process. Further, the air or suitable liquid 330 may be used to flush the measurement chamber between different samples. The 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 step 210, the arrangement is configured to direct optical radiation at the suspension in the measurement chamber 324. A more detailed example of the measurement chamber is below. In an embodiment, the wavelength of the optical radiation directed to the measurement chamber is selected based on the one or more colour components fed to the sample.

In step 212, the arrangement is configured to detect optically interaction of the optical radiation with the suspension. In an embodiment, a filter passing through given wavelengths is applied before a detector when detecting optically interaction of the optical radiation with the suspension. In an embodiment, such a filter is selected, which passes through wavelengths corresponding to a complementary colour of a colour component fed to the sample. For example, when the colour component fed to the sample corresponds to yellow colour, the complementary colour of blue may be used. Instead of utilising filters a light source emitting the desired wavelengths may be used as one skilled in the art is aware.

In step 214, the arrangement is configured to determine the amount of one or more different components in the sample based on the detection.

In an embodiment, the temperature of the suspension in the measurement chamber may be adjusted. The measurement chamber may comprise temperature control input 332. The measurement chamber may comprise an appropriate temperature adjustment unit 334 such as a heater and/or a cooler.

In an embodiment, the arrangement may comprise a controller 336 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 arrangement 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. A camera arrangement 406 is located at one side of the chamber behind the window 404. Sources of optical radiation or light sources 408, 410 are located at opposite sides of the chamber behind the windows 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 camera 406. The filters may pass through a given wavelength or wavelength range. There may also be separate light sources foo all required wavelength ranges.

In an embodiment, the optical radiation from the source 410 on the opposite side of the camera 406 passes through the suspension sample to the camera. The camera captures an image in which outlines of the components in the suspension are visible and thus the number or amount of the components may be determined.

Further, the optical radiation from the source 408 on the same side as the camera 406. The optical radiation either absorbs into the components in suspension or is reflected from the components, depending on whether the components have absorbed the colour components. This enables distinguishing from the image captured by the camera different components from each other. Typically, organic components absorb the colour fed to the suspension, but the non-organic components do not.

In an embodiment, the wavelength of the optical radiation has a range of 400 to 800 nm and a suitable filter is applied in from of the camera, the filter being selected on the basis of the colour components fed to the sample. Alternatively, 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. Also infrared wavelengths may be used.

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

In an embodiment, the analysis can be made in the controller controlling the apparatus.

In an embodiment, the temperature of the suspension in the measurement chamber may be adjusted, by the controller controlling the apparatus, after the measurement and another measurement may be performed when the suspension has reached the desired temperature. Different colour components may react differently to different temperatures. For example, the colour of a component may change based on the temperature. Thus, more information may be obtained from the same sample by utilising different temperatures.

Let us first next 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. A camera arrangement 406 is located at one side of the chamber behind the window 404. Sources of optical radiation or light sources 408, 410 are located on the same side of the chamber behind the window 404. There is a diffuse reflector 420 on the opposite side of the chamber behind the window 402.

In an embodiment, the optical radiation from the source 410 may reflect from the reflector 420 to the camera 406, passing through the suspension sample. The camera captures an image in which outlines of the components in the suspension are visible and thus the number or amount of the components may be determined.

Further, the optical radiation from the source 408 on the same side as the camera 406. The optical radiation either absorbs into the components in suspension or is reflected from the components, depending on whether the components have absorbed the colour components. This enables distinguishing from the image captured by the camera different components from each other. Typically, organic components absorb the colour fed to the suspension, but the non-organic components do not. Based on above it is possible to determine the amount of one or more different components in the suspension sample.

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 organic 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 feeding one or more colour components to the sample; 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 detecting optically interaction of the optical radiation with the suspension and means for determining the amount of different components in the 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.