METHOD AND APPRATUS TO PROCESS CELLULOSE FIBRES

Abstract

A method to process cellulose fibres, preferably including wood fibres, comprises the steps: Deriving first fibres having a first property from a first raw material comprising cellulose fibres, Milling the first fibres to provide milled fibres, preferably with an average characteristic fibre dimension greater than 100 m, Drying the first fibres to provide dried fibres having a residual moisture less than 10% by weight, Adding one or more polymers, preferably including Lignin, to the dried fibres to provide a predetermined mixture including a polymer weight fraction of at least 5%, Processing the predetermined mixture to provide granules with an average characteristic granule dimension between 2 to 6 mm.

Claims

1. Method to process cellulose fibres (21), preferably including wood fibres, comprising the steps: Deriving first fibres (22) having a first property from a first raw material comprising cellulose fibres (21), S2 Milling the first fibres (22) to provide milled fibres (23), preferably with an average characteristic fibre dimension greater than 100 m, S3 Drying the milled fibres (23) to provide dried fibres (24) having a residual moisture less than 10% by weight, S4 Adding one or more polymers (25), preferably including Lignin, to the dried fibres (24) to provide a predetermined mixture (26) including a polymer weight fraction of at least 5%, S5 Processing the predetermined mixture (26) to provide granules (27) with an average characteristic granule dimension between 2 to 6 mm.

2. Method according to claim 1, wherein the cellulose fibres (21) originate from a single species of plants.

3. Method according to claim 1, wherein step S1 includes: Passing some of the first fibres (22) through a first dimension sensitive device (9) and/or retaining some of the first fibres (22) by a second dimension sensitive device (9a).

4. Method according to claim 1, wherein step S1 includes Selecting first fibres based on their colour and/or their geometry.

5. Method according to claim 1, wherein step S2 is performed with a grinding device (11) and preferably with a third dimension sensitive device (9b).

6. Method according to claim 1, wherein step S3 is performed with a vacuum dryer or dispersion dryer.

7. Method according to claim 1, wherein for step S4 at least one of the polymers is selected from the following group including a thermoplast, lignin, polyethylene, polypropylene, polystyrene, polyamide, polycarbonate, acrylonitrile butadiene styrene, polymethyl methacrylate and polyoxymethylene.

8. Method according to claim 1, wherein step S4 includes: Adding second fibres (22a) from a second raw material to the predetermined mixture (26).

9. Method according to claim 1, wherein step S5 is performed with an extruder or a multi screw extruder.

10. Method according to claim 1, further comprising: S6 Supplying the granules (27) to a storage tank (8), from which some of the granules (27) may be transferred to a mobile tank.

11. Method according to claim 1, wherein step S1 also includes deriving second fibres (22a) having a second property from the first raw material, the method further comprising: S7 Forming fuel pellets (28) from the second fibres (22a).

12. Method according to claim 1, wherein step S1 also includes deriving second fibres (22a) having a second property from the first raw material, the method further comprising the steps: S8 Processing the second fibres to gain thermal energy Q [J], S9 Providing the thermal energy Q during step S3 or step S4 or step S5.

13. Apparatus (1) for processing cellulose fibres (21), preferably including wood fibres, comprising: deriving means (2) arranged for deriving first fibres (22) having a first property from a first raw material comprising cellulose fibres (21), milling means (3) arranged for receiving the first fibres (22) from the deriving means (2), for milling the first fibres (22), for providing milled fibres (23) with an average characteristic fibre dimension greater than 100 m, drying means (4) arranged for receiving the milled fibres (23) from the milling means (3), for drying the milled fibres (23), for providing dried fibres (24) having a residual moisture less than 10% by weight, adding means (5) arranged for receiving the dried fibres (24) from the drying means (4), for adding one or more polymers (25), preferably including Lignin, to the dried fibres (24), for providing a predetermined mixture (26) including a polymer weight fraction of at least 5%, processing means (6) arranged for receiving the predetermined mixture (26) from the adding means (5), for processing the predetermined mixture (26), for providing granules (27) with an average characteristic granule dimension between 2 to 6 mm.

14. Apparatus according to claim 13, wherein the deriving means (2) comprises a first dimension sensitive device (9) arranged for being passed by some of the first fibres (22) and/or a second dimension sensitive device (9a) arranged for retaining some of the first fibres (22).

15. Apparatus according to claim 13, wherein the deriving means (2) comprise an optical device arranged for determining the colour and/or the geometry of some of the first fibres (22).

16. Apparatus according to claim 13, wherein the milling means (3) comprise grinding device (11) and a third dimension sensitive device (9b).

17. Apparatus according to claim 13, wherein the drying means (4) comprise a vacuum dryer or a dispersion dryer.

18. Apparatus according to claim 13, wherein the adding means comprise a mixing device for setting a fraction of the dried fibres from a first raw material (first dried fibres) and a fraction of dried fibres from a second raw material (second dried fibres).

19. Apparatus according to claim 13, comprising an extruder or a multi screw extruder arranged for processing the predetermined mixture (26) and for providing granules (27) with an average characteristic granule dimension between 2 to 6 mm.

20. Apparatus according to claim 13, further comprising a storage tank (8) arranged for receiving some of the granules (27) and arranged for releasing some of the granules (27) to a mobile tank.

21. Apparatus according to claim 13, further comprising pelletising device (10) arranged for forming fuel pellets (28) from second fibres (22a) having a second property, wherein the second fibres (22a) are derivable from the first raw material by the deriving means (2).

22. Apparatus according to claim 13, wherein the deriving means (2) are further arranged for deriving second fibres (22a) having a second property from the first raw material comprising cellulose fibres (21), further comprising a heat exchanger (7) arranged for transferring thermal energy Q gained from the second fibres (22a) to at least one of the drying means (4), the adding means (5) and the processing means (6).

23. Product produced by a method according to claim 1.

Description

BRIEF DESCRIPTION OF EMBODIMENTS

[0096] FIG. 1 shows a flowchart of the method according to the first aspect;

[0097] FIG. 2 shows an apparatus according to the second aspect.

[0098] FIG. 1 shows the method to process cellulose fibres, preferably including wood fibres, comprising the steps: [0099] S1 Deriving first fibres having a first property from a first raw material comprising cellulose fibres, [0100] S2 Milling the first fibres to provide milled fibres, [0101] S3 Drying the first fibres to provide dried fibres having a residual moisture less than 10% by weight, [0102] S4 Adding one or more polymers to the dried fibres to provide a predetermined mixture including a polymer weight fraction of at least 5%, [0103] S5 Processing the predetermined mixture to provide granules with an average characteristic granule dimension between 2 to 6 mm.

[0104] Step S1 serves to select and to separate desired first fibres from the whole of the cellulose fibres stemming from the first raw material. The result of step S1 is that first fibres selected from the whole of the cellulose fibres will predominantly be subjected to the steps S2 to S5. The deriving can be based on the fibres' dimension, weight, colour and/or geometry and can be performed by a dimension sensitive device, a weight sensitive device, a colour sensitive device and/or a geometry sensitive device. The first fibres are released to be milled during step S2. Alternatively, the first fibres are released to be dried during step S3.

[0105] Step S2 serves to provide milled fibres with an average characteristic fibre dimension making use of most of the first fibres provided by step S1. A grinding device may be used to break bigger fibres into smaller ones, the smaller ones falling into a preferred dimensional range. Step S2 can be performed continuously and/or in combination with step S1. During step S2 the dimensional variation on the fibres is reduced. The milled fibres are released to be dried during step S3. Alternatively, the milled fibres are released to be combined with one or more polymers during step S4.

[0106] Step S3 serves to provide dried fibres making use of most of the milled fibres. The milled fibres can be exposed to the predetermined atmosphere and/or to radiating heat sources. The milled fibres can be dried continuously in a channel or intermittently using one or more chambers. Drying is terminated when an intended residual moisture of the fibres is achieved. The dried fibres are released to be combined with one or more polymers. Alternatively, the dried fibres are released to be milled during step S2.

[0107] Step S4 serves to provide a mixture comprising dried fibres and at least one polymer, the mixture having a defined polymer weight fraction. Preferably, agglomerations of the fibres or polymer(s) within the predetermined mixture are disintegrated. A mixing operation can be combined with conveying the predetermined mixture towards step S5.

[0108] Step S5 serves to provide granules having a predetermined characteristic dimension from the predetermined mixture. Subjecting the predetermined mixture to increased temperature and/or increased pressure, particularly by an extruder, leads to the formation of the granules. This step can be combined with step S4. These granules can be conveniently stored and can be converted to the finished product at a later point in time.

[0109] Preferably, the above method comprises at least one of the following: [0110] the fibres temperature is kept below 120 C., preferably below 90 C., [0111] the cellulose fibres originate from a single species of plants, [0112] a drying operation is performed prior to step S2, when the fibres moisture exceeds 15%, to improve the milling, [0113] a first dimension sensitive device through which some of the first fibres are passed and a second dimension sensitive device by which some of the first fibres are retained are used during step S1, [0114] at least one of the polymers to be added to the dried fibres is a thermoplast or is chosen from the following group of polymers including lignin, polyethylene, polypropylene, polystyrene, polyamide, polycarbonate, acrylonitrile butadiene styrene, polymethyl methacrylate and polyoxymethylene, [0115] the dried fibres are guided through a fibre guiding device arranged for containing a pressurised atmosphere for reducing or avoiding the influx of ambient air, [0116] second fibres are derived by step S1 and are formed to fuel pellets, [0117] second fibres are derived by step S1, are processed to gain thermal energy Q and the thermal energy Q is provided during step S3, S4 or S5.

[0118] FIG. 2 shows an apparatus 1 according to the second aspect. The apparatus comprises [0119] deriving means 2 arranged for deriving first fibres having a first property from a first raw material comprising cellulose fibres, [0120] milling means 3 arranged for receiving the first fibres from the deriving means 2, for milling the first fibres, for providing milled fibres with an average characteristic fibre dimension greater than 100 m, [0121] drying means 4 arranged for receiving the milled fibres from the milling means 3, for drying the milled fibres, for providing dried fibres having a residual moisture less than 10% by weight, [0122] adding means 5 arranged for receiving the dried fibres from the drying means 4, for adding one or more polymers, preferably including Lignin, to the dried fibres, for providing a predetermined mixture including a polymer weight fraction of at least 5%, and [0123] processing means 6 arranged for receiving the predetermined mixture from the adding means 5, for processing the predetermined mixture, for providing granules with an average characteristic granule dimension between 2 to 6 mm.

[0124] The deriving means serve to select and to separate desired first fibres from the whole of the cellulose fibres stemming from the first raw material. The deriving means can comprise one or more dimension sensitive devices, a geometry sensitive device, colour sensitive device, receive, an optical device and/or the CCD-camera. The deriving means can release the first fibres, particularly continuously, to the milling means through a pipe or channel. Alternatively, the deriving means can release the first fibres to the drying means.

[0125] The milling means serve to provide milled fibres with an average characteristic fibre dimension making use of most of the first fibres provided by the deriving means. The milling means can also reduce the dimensional variation among the fibres. A grinding device may be used to break bigger fibres into smaller ones, the smaller ones falling into a preferred dimensional range. The milling means can operate continuously and in combination with the deriving means. The milling means can release the milled fibres to the drying means through a pipe or channel. Alternatively, the milling means can release the milled fibres to the adding means.

[0126] The drying means serve to provide dried fibres making use of most of the milled fibres. The drying means can comprise the predetermined atmosphere and/or radiating heat sources. The drying means can dry the milled fibres continuously in a channel. Alternatively, the milled fibres can be dried intermittently in one or more chambers. Preferably, one of these chambers is temporarily open for being filled with milled fibres and a second chamber is closed while drying. The drying means arranged to terminate drying when an intended residual moisture of the fibres is achieved. The drying means can release the dried fibres to the adding means through a pipe or channel. Alternatively, the drying means can release the dried fibres to the milling means.

[0127] The adding means serve to provide a mixture comprising dried fibres and at least one polymer, the mixture having a defined polymer weight fraction. Preferably, the adding means are arranged for disintegrating agglomerations of the fibres or the polymer(s) within the predetermined mixture. The adding means can have a mixing device which is preferably arranged for conveying the predetermined mixture towards the processing means. The adding means can release the predetermined mixture to the processing means through a pipe or channel.

[0128] The processing means serve to provide granules having a predetermined characteristic dimension making use of the predetermined mixture. The processing means are arranged for subjecting the predetermined mixture to an increased temperature and/or increased pressure leading to the formation of the granules. These granules can be conveniently stored and can be converted to finished products at a later point in time.

[0129] Preferably, the apparatus comprises at least one of the following: [0130] a means of the apparatus which is controlled to keep the fibres temperature below 120 C., preferably below 90 C., and/or [0131] drying means which are arranged upstream of the milling means arranged for reducing the fibres moisture to a value below 15%, and/or [0132] deriving means comprising a first dimension sensitive device for which some of the first fibres may be passed and a second dimension sensitive device by which some of the first fibres can be retained, wherein the second dimension sensitive device is arranged downstream of the first dimension sensitive device, and/or [0133] the fibre guiding device arranged for containing a pressurised atmosphere for reducing or avoiding the influx of ambient air and arranged between the drying means and the mixing means, and/or [0134] the pelletising device arranged for forming fuel pellets from second fibres derived by the deriving means, particularly rejected by the first dimension sensitive device, and/or [0135] the heat exchanger arranged for transferring thermal energy Q gained from the second fibres to at least one of the drying means, the adding means and the processing means, and/or [0136] the wetting device arranged between the deriving means and the milling means, and/or [0137] the moisture detection device arranged upstream of the milling means.

LIST OF REFERENCE NUMERALS

[0138] 1 apparatus [0139] 2 deriving means [0140] 3 milling means [0141] 4 drying means [0142] 5 adding means [0143] 6 processing means [0144] 7 heat exchanger [0145] 8 storage tank [0146] 9, 9a, 9b dimension sensitive device [0147] 10 pelletising device [0148] 11 grinding device [0149] 21 cellulose fibres [0150] 22 first fibres [0151] 22a second fibres [0152] 23 milled fibres [0153] 24 dried fibres [0154] 25 polymer [0155] 26 predetermined mixture [0156] 27 granules [0157] 28 fuel pellets