DE3342812A1 - DEVICE AND METHOD FOR THE EXTRUSION OF CELLULOSE-CONTAINING SUBSTANCES - Google Patents

Description

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description

The invention relates to an extrusion apparatus and method for efficient handling and extrusion of material that has previously caused significant processing difficulties. These include, for example Wood chips, sawdust and other wood debris, urban waste solids and crop residues. The invention particularly relates to an apparatus and a

■ 15 processes that use a screw transition zone in a barrel to balance material flow and help build up relatively high pressures and temperatures; In addition, the extrusion ^device has an adjustable nozzle, which also facilitates the extrusion work.

There are already various methods and devices for the comminution of cellulose or fiber-containing Substances for the production of a comminuted or

OR fiber product known. For example, it is shredded Wood is used in the manufacture of so-called fiberboard. The frayed wood can thereby be formed by treating wood chips in a large boiler with high pressure steam, followed by a sudden pressure release is applied to split the wood chips and break them into fibers, in order to get the shredded product. Another known method is slicing of wood chips, whereby after an initial pressure treatment the wood chips become a large

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plate refiner are placed in the they are treated with pressure in a similar manner. Large commercial units of this type can use wood chips shred to essentially single fiber size, however, this requires a very large motor, for example with 2000 HP. An essential one The difficulty with disk shredders is the expenditure for maintenance and replacement of parts. The device wears out easily and essential working parts are used up very quickly, so that it is altogether uneconomical.

Urban solid waste has so far been treated similarly, to make them uniform and suitable as fuel. A method of treating urban Waste solids is the hydropulping process. In this process, a sludge of waste and water is discharged into a large vessel, which has a perforated bottom. A rotating one Scraper knife lies above the perforated floor and is used to shred and split the through Solids entering the bottom of the vessel.

However, all known methods have the major disadvantage that they consume large amounts of energy. For example, shredding wood chips into slices can be unreasonably expensive in terms of the energy balance, despite its effectiveness in terms of producing the desired shredded wood. This follows not only from the high consumption of electric power for the strong drive motor and of a kind used for the treatment of wood chips amount of steam, but also from the fact that large amounts of water pumped and handled together with the wood chips Müs ^sen ·

Attempts have therefore already been made to extrude wood chips or other cellulose or fiber-containing substances. the Advantages of extruding these materials are theoretically obvious, especially from the point of view of the Energy balance. In practice, however, there are significant difficulties, which in the great Difficulty in smooth and effective extrusion from rough and coarse materials such as wood chips. Attempts at the extrusion of wood chips have resulted in either excessive suction and blowing or too much other signs of uneven operation, or, more often, resulted in complete misplacement the machine, which required shutdown and cleaning.

It is therefore the object of the invention to create a device and a method with which cellulose- or fibrous materials can be effectively shredded and fiberized in a commercially acceptable manner.

The features of claim 1 and claim 13 serve to solve this problem.

With the device according to the invention and the method can contain substances such as wood chips, sawdust and other wood residues, urban waste solids and crop residues, e.g. wheat straw, corn stems or bagasse can be processed without difficulty. With the help of Extruders according to the invention can also process textured whole soybeans, which are conventional have high fat content.

The extruder according to the invention has an elongated one Cylinder with a material inlet and a material outlet at opposite ends, woboi in dom

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Cylinder a screw is rotatable, which serves to convey the material from the inlet end to the outlet end. the Auger is designed to smooth the flow of material in the device and prevent clogging prevented. It has been found that this feature, along with nozzle means at the outlet end of the cylinder, which is used to change the passage cross-section at the nozzle opening during operation of the extruder serves, the processing of the aforementioned substances is made much easier.

The extruder screw advantageously has a first, catchy feed zone with only one screw thread at the inlet end of the cylinder, while a transition zone is downstream of the feed zone and has first and second helical flights, respectively represent a series of helical windings. The first and second threads alternate along the length of the transition zone and the height of the first screw flight is less than that of the second screw flight. Finally, the screw has a compression zone downstream of the transition zone, which extending towards the outlet end of the cylinder. The compression zone has two or three Screw threads to increase the compression forces on the material.

In a preferred embodiment, it increases in size the height of the first screw thread in the transition zone gradually and progressively until it is the height of the corresponds to the second screw thread. In practice, the first screw thread practically starts at one height from zero and gradually increases to the level of the second screw thread over a distance of 1/4 turn up to 10 turns of the first screw turn, whether

a greater or lesser number of revolutions can be used. In a preferred embodiment the core diameter is constant, in another it changes over its entire length.
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In a preferred embodiment, it is adjustable The nozzle arrangement depends on the pressure, i.e. the effective dimensions of the nozzle opening are dependent on Controlled pressure fluctuations in the cylinder. It has been found that this is the working characteristics of the Extruder improved.

The invention is explained in more detail with reference to figures; show it:

Figure 1 is a side view of an embodiment;

FIG. 2 shows an end view of the device according to FIG. 1;

FIG. 3 shows an enlarged vertical partial section along the line 3-3 of FIG. 2 and shows the feed zone, the transition zone and the compression zone of the extruder screw;

Figure 4 is an enlarged vertical partial section through the outlet end of the extruder showing an adjustable nozzle;

Figure 5 is a side view of the preferred screw transition zone showing the gradual and increasing the pitch of the first screw flight of the screw; and

FIG. 6 shows a vertical section through the section shown in FIG.

Figures 1 and 2 show an extruder 10 with a primary hopper 12, which is inclined with a Conveyor screw 14 is provided. A secondary hopper 16 is also part of the extruder 10 and is provided with a twin screw feeder 18 and an extruder assembly 20. The loading hopper 12 has the usual structure and has the usual supports 22. The screw conveyor 14 is inclined within the feed hopper 12 and extends through the open one top end up. A conveyor chute 24 is used to transport up from the feed hopper 12 Transfer material to secondary hopper 16. The secondary feed hopper 16 also has a structure known per se and has supports 26 and an end open at the top for the delivery of the material from the chute 24. Both loading hoppers 12 and 16 are preferably nearby their bases equipped with rotating scrapers, so that there is prevented a clumping of material will.

The extruder device 20 comprises an elongated, multi-section tubular cylinder 27, which has an inlet 28 for material, which with a twin screw screw 18 in connection is, and it also has an adjustable nozzle 30, which is located in the vicinity of the opposite Outlet end of the cylinder 27 is arranged.

The extruder device 20 also has an elongated, multiply subdivided screw 32, which in the cylinder

which is arranged 27 and rotatable therein by a motor 34 and a transmission 36. The screw 32 is used to this, material from inlet 28 along the length of cylinder 27 and finally through the adjustable nozzle 30 to promote; In addition, the screw 32 serves to expose the material to shear forces and heat in the to be transferred to the material in the manner to be described below.

In the illustrated embodiment, the cylinder is 27 with a total of 5 axially aligned, interconnected tubular pieces 38 to 46 and with a somewhat shorter compression piece 48, which is spirally ribbed inside and which has a conical

"Has 15 blunt-like through-hole. Finally For example, the nozzle 30 is attached to the outlet end of the piece 48 to receive material from there as shown in FIG.

Similarly, the auger 32 is made up of sections, generally speaking referred to as a feed zone 50, may be referred to as a transition zone 52 and a compression zone 54. The feed zone 52 has a single-flight screw element 56 which is arranged in the tubular piece 38 and for Transfer of material from inlet 28 along the length of cylinder 27 to transition zone 52 is used.

The transition zone 52 is in the form of a special screw element 58 which is located downstream of the first screw element 56 lies and is coupled to this. As can best be seen from Figure 3, is between the screw elements 56 and 58, a vapor barrier 74. This vapor barrier is for the Extrusion device not absolutely necessary. The screw element 58 forming the transition zone 52 has

an elongated body having a generally cylindrical outer surface 60 and a constant or decreasing one Has core diameter. It is of course also possible to use a screw with a variable core diameter to use. Axially spaced first and second threads 62 and 64 are provided on the core, extending outwardly from outer surface 60 and generally helically along the Extend the length of the screw body. According to FIGS. 5 and 6, the first and second thread turns 62 and 64 actually represent a series of helical windings with the two threads running along alternate with the body. It can also be seen that the height of the first thread 62, so the distance from of the surface 62 to the outer surface of the thread turn is smaller than for the second thread turn 64. In the illustrated Embodiment, the first thread 62 starts at a height of zero and progressively increases, namely during about 1 1/4 turns of the thread until the height of the first thread 62 of the second thread 64 corresponds. This gradual increase in thread pitch is best shown in FIGS 6 and 6, while the starting point or zero point 66 of the first thread turn 62 can be seen in FIG.

As will be explained in more detail below, the task of the transition zone 52 is to keep the flow of rough, coarse Smooth out any material running through the extruder to prevent misplacement of the device.

The compression zone 54 takes up the remainder of the length of the extruder barrel 27, i.e. the compression zone 54 lies in the pieces 40 to 48. The compression zone 54 is formed from one or more twin screw screws, for example from the screw elements 68

and 70 shown in FIGS. 3 and 4. The compression zone 54 also has a conical screw element 72 that extends within the piece 48 according to Figure 4 is. If necessary, there is a vapor barrier 74 between the respective screw elements which form the entire compression zone 54.

It is clear to the person skilled in the art that the screw elements described are essentially tubular from individual Sections are constructed and have a central bore. The entire extruder is usually with equipped with a central, driven spline shaft, which the entire screw 32 forming screw elements as well as the vapor barriers. The tubular structure of the screw element 58 is shown in FIG 76 shown.

The nozzle 30 has the following components: An elongated, tubular, axially displaceable piston head piece 78, an elongated, axially rotatable and partially arranged in the piston head piece 78 nozzle needle 80, hydraulic devices 82, which are functionally coupled to the piston head piece 78 and for axial displacement the latter serves in both axial directions, pressure sensor 84 which is functionally in the cylinder 27 are arranged and serve to measure the pressure prevailing therein, and coupling devices 86, which the pressure sensors 84 and the hydraulic device 82 functionally connect.

The piston head piece 78 has a side wall 86 as well inner, bore-defining wall areas which together form a continuous bore 88, the extend through the length of the piston head piece 78.

In particular, a first frustoconical wall ab-

Section 90 is provided which converges inwardly from the extreme inlet end of the piston head piece 78 extends. A second frustoconical wall section 92 having a first end of largest diameter 94 and a second end of smallest diameter 96 is provided, as is a third wall section 98 of the cylindrical structure, which extends around the second The end of the smallest diameter 96 of the wall portion 92 extends.

The wall portions 90 and 92 together form a frustoconical inlet end bore portion while wall portion 98 has an outlet end bore portion of substantially constant diameter forms. The diameter of the bore section at the outlet end is essentially the same as the diameter of the smallest end 96 of the wall section 92, which is free of obstacles for the material to flow through is.

The outer surface of the piston head piece 78 has an irregular structure and has four circumferentially distributed peripheral indentations, not shown, and at the outlet end of the head piece 78 lie, while an annular, outwardly protruding structure 100 between the inlet and outlet ends of the Piston head piece 78 lies. Each smooth, cylindrical Support surfaces 102 and 104 extend in opposite directions from the opposite ends of the structure 100 for the purpose explained below.

The nozzle needle 80 has an elongated, frustoconical shape Shape and is formed by a smooth, converging side wall and a circular end wall.

The largest diameter end of the nozzle

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needle 80 is attached to the end of the conical screw element 72, which has the smallest diameter and therefore forms an extension of the latter. The nozzle needle 80 therefore rotates during operation of the extrusion device together with the screw element 72. Preferably, the nozzle needle 80 is integral with the Screw element 72.

It can be seen in Figure 4 that the converging side wall of the nozzle needle 80 with respect to the wall section 92 is complementarily shaped to thereby create an annular extrusion opening 106 between the side wall of the To form nozzle needle 80 and the wall section 92. It can also be seen that the cross section of the extrusion opening 106 can be changed by axial displacement of the piston head piece 78 in a manner to be explained in more detail.

The overall adjustable nozzle 30 has an annular / apertured stationary part 108, which is screwed to the outlet end of the compression-causing piece 48 as shown. The innermost surface of the stationary part 108 is smooth and circular and has a circular recess in which a seal 110 is located. The stationary part 108 is shaped so that it together with the Forms bearing surfaces 102 and 104 and with the structure 100 first and second hydraulic fluid chambers 112 and 114. A pair of bores 116, 118 penetrate the stationary part 108 and communicate with the hydraulic fluid chambers 112, 114 in connection. Lines 120, 122 shown schematically for hydraulic fluid are connected to the respective Bore 116 or 118 according to Figure 4 connected.

The hydraulic device 82 has a conventional structure and is therefore only shown schematically. The expert

knows, however, that and how the hydraulic device 82 delivers hydraulic fluid under pressure to either bore 112 or leads to the bore 114, depending on the pressure conditions in the cylinder 27, which of the Pressure sensor 84 are measured. The hydraulic device 82 thus has a conventional hydraulic fluid reservoir, a hydraulic pump and solenoid valves.

The pressure sensor 84 is usually a pressure transducer which is arranged in a suitable bore, the extends through the side wall of compression piece 48. The pressure sensor 84 can thus determine the pressure conditions Measure in cylinder 27 at the inlet to nozzle 30. If there is excessive pressure in the cylinder 27 are measured, hydraulic fluid is introduced into the hydraulic fluid chamber 112, whereby the piston head piece 78 is shifted to the right in FIG. 4 and thereby increases the cross section of the extrusion opening 106, causing the pressure to drop. On the other hand, if too low a pressure is measured, then hydraulic fluid becomes introduced into the hydraulic fluid chamber 114 and thereby displaced the piston head piece 78 to the left in FIG. whereby the cross-section of the nozzle opening 106 is reduced and the cylinder temperature is increased.

The nozzle 30 described above is detailed in U.S. Patent Application 06/210684 dated Nov. 26, 1980 described. The disclosure of this application or other parallel applications is hereby expressly lent Referenced.

In addition, an external hydraulic piston and cylinder assembly can be used in place of the one used to slide the piston headpiece 78 can be used or used to support it.

It has been shown that the extrusion of materials such as wood chips, wood-like materials, paper, solid waste materials a community, crop residues and whole or ground soybeans with the device described can be significantly improved. Generally speaking, the effect of the transition zone is related with the adjustable nozzle 30 in it to balance the flow in the barrel 27 of the extruder to to prevent an embarrassment. It has been found that the transition zone 52 reduces the shear forces on the material between the draw-in zone 50 having low shear forces and the compression zone having high shear forces 54 gradually increases while the adjustable nozzle 30 provides good continuity of operation Allocation of the nozzle cross-sectional opening to the amount of incoming material and to the acting on it Maintains shear and working conditions. These components facilitate the sometimes difficult extrusion of unprocessed, coarse materials, as described above, are very important. Tests with known Extrusion devices have been laying or uneconomical for extruding wood chips Operation performed, while the device according to the invention the same input product without difficulty could handle.

In the extrusion of cellulose or fiber-containing materials, liquid is expediently added before or during the extrusion process in order to add a total moisture content, ie inherent moisture plus added moisture, of about 5 to 75% by weight and preferably of about 30 to 50% by weight obtain. During extrusion, the temperature should be maintained in the cylinder 27 of the extruder at about 100-340 ⁰ C. The pressure conditions in the cylinder 27 should-

th are above about 14 bar, preferably between about 14 bar to 350 bar and in particular between about 53 bar up to 105 bar. The material is said to be held in cylinder 27 for about 15 to 200 seconds during extrusion , preferably for about 30 to 60 seconds. This is not just done by adjusting the speed of rotation of the Screw 32, but also by adjusting the free cross section of the extrusion opening 106 between the The nozzle needle 80 and the wall section 92 are reached. For example, this distance is about 0.025 mm to about 12.7 mm, preferably 0.25 mm to about 5 mm. As already mentioned, this setting takes place advantageously as a function of the pressure conditions within the cylinder 27.

In the extrusion of wood chips to produce a fiberized product that is used for manufacturing of fibreboard is suitable, wood chips of suitable average dimensions, for example 25 mm Taken as they are, without being pre-soaked or pre-moistened, and they are so in the Cylinder 27 of the extruder device 20 is fed. For some types of wood, however, it can be useful to use the Moisten the wood beforehand. Virtually any wood can be used as wood, i.e. hardwood and softwood. Typical woods are rubber tree, aspen wood, poplar wood, pine or walnut wood, which typically one Have a moisture content of 20 to 60% by weight. The extruder is usually running at 75 to 600 rpm, preferably operated at 150 to 300 rpm.

During the initial start-up, the device normally sucks and blows, which is achieved by changing the effective cross section of the extrusion opening 106 regulated is until this opening of the feed rate for

Wood chip corresponds. If there is a continuous Has ceased operation, then the nozzle 30 is adjusted so that its nozzle opening 106 changes, if the pressure in the cylinder 27 deviates significantly from, for example, 70 bar. This setting value leaves change over a considerable range, which depends on the type of end product desired, namely whether this should have smaller or larger particle sizes.

In the extrusion of urban waste solids and For crop residues, what has been said above applies essentially. Typically it should be total moisture such input products have an average of about 40 wt. ° and the pressure setting for the nozzle arrangement is usually around 70 bar.

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Claims (23)

UEXKÜLL & STOLBERG PATENT LAWYERS BESELERSTRASSE 4 D-20O0 HAMBURQ 52 EUROPEAN PATENT ATTORNEYS DR JD FRHR from UEXKULL DR ULRICH GRAF STOLBERG DlPL ING. JÜRGEN SUCHANTKE DIPL ING. ARNULF HUBER DR ALLARD by KAMEKE DR KARL-HEINZ SCHULMEYER WENGER MANUFACTURING
Sabetha, Kansas, V.St.A. (Prio .: Nov. 26, 1982 US 06/444 807 - 20336 / HU / wo) November 1983 Device and method for the extrusion of cellulosic materials Claims Extrusion device, characterized by: an elongated body having a generally cylindrical outer surface and through - A structure each having axially spaced, first and second screw threads, the extending outwardly from the surface and along the length of the body in general run helically, - wherein the first and second screw threads each form a sequence of screw sections, which alternate along the length of the body, and - The height of the first screw turns is less than the height of the second screw turns. 2. Apparatus according to claim 1, characterized in that the height of the first screw threads gradually - (O borrowed and progressively increases until it is of height corresponds to the second thread. 3. Apparatus according to claim 2, characterized in that the height of the first screw threads - \ 5 that of the second screw turns increases by about 1 1/4 to 10 turns of the first screw turns, although more or fewer turns can be provided. 4. Apparatus according to claim 1, characterized in that that the core diameter of the body is essentially constant over its length. 5. Extruder, characterized by: an elongated cylinder having a material inlet at one end and a material inlet at the other end Having material outlet; - an elongated screw rotatable about the axis and vapor barriers, both of which are supported by a splined shaft in the cylinder to promote the mate rials are driven from the inlet end to the outlet end, - wherein the screw has a screw element and vapor barriers and the following features: an elongated body having a generally cylindrical outer surface and - A structure that forms each axially spaced, first and second screw threads, the extend outward from the surface and are generally helical along the length of the body, - wherein the first and second screw threads each form a sequence of screw surfaces, being the first and second screw surfaces alternate along the length of the body, and where - the height of the first screw turns is less than the height of the second screw turns, and through - a nozzle at the outlet end of the cylinder for forming an extrusion opening, the nozzle means for changing the effective cross-section of the nozzle opening during operation of the extruder. 6. Apparatus according to claim 5, characterized in that the height of the first screw threads gradually and increases progressively until it corresponds to the height of the second helix. 7. Apparatus according to claim 5, characterized in that the core diameter of the body is about its length is essentially constant. 8. Apparatus according to claim 5, characterized in that the nozzle has the following features: - A tubular head piece with a material feed end, a material discharge end and inner bore wall sections; · - J J4ZÖ I - An elongate, rotatable about the axis element which is at least partially in the bore and at least a part of the bore-forming wall sections is shaped complementarily to a Extrusion opening between the outer surface of the Element and the part of the wall sections to form; and Means for axially displacing the head piece or the element with respect to the other to change the effective cross-section of the Extrusion opening. 9. Apparatus according to claim 8, characterized in that the bore-forming wall sections a frustoconical inlet end bore portion form the one end with the largest diameter at the inlet end of the header and one end with having the smallest diameter in the central region of the head piece, the wall sections also forming an outlet end bore portion communicating with the inlet end bore portion stands, the diameter of the outlet end bore portion substantially along its entire length the same size as the diameter of the end with the smallest diameter of the truncated cone Inlet end bore section is that the frustoconical Element complementary to at least a portion of the frustoconical inlet end bore portion is shaped to have an annular extrusion opening between the element and the To form wall sections which form part of the tapered inlet end bore section. 10. The device according to claim 8, characterized in that the displacement device Einrichtun- · »·" · - ■ · 33428 1 gene has / which hold the head piece for axial displacement with respect to the element. 11. The device according to claim 8, characterized by a device for moving the head piece as a function of pressure changes in the extruder. 12. The device according to claim 11, characterized by: - Hydraulic devices which are functionally connected to the head piece and which can be used optionally axial displacement of the head piece is used in both axial directions; - a functionally arranged in the extruder device for measuring the prevailing therein Pressure; and a device which functionally couples the pressure measuring device and the hydraulic device for actuating the latter for an axial displacement of the head piece in a desired axial direction. 13. A method for extruding a cellulosic or fiber-containing substance, characterized by the following steps: - Choosing a lot of a substance like wood, woody material, paper, urban waste solids, Crop residues and / or mixtures thereof, the fabric having a total moisture content has from about 5 to 75 weight percent; - Introducing this substance into the elongated cylinder of an extruder and rotating the extruder screw to convey the fabric along the length of the cylinder; - wherein the transferring step involves gradually increasing the shear and compression forces closes that exerted on the material during its movement along the length of the cylinder will; and - Extruding the substance through a nozzle, the cross-section of the nozzle during operation of the extruder is readjusted. 14. The method according to claim 13, characterized in that the moisture content is about 30 to 50 Weight% is. 15. The method according to claim 13, characterized in that the temperature in the extruder barrel at about 100 ⁰ C to about 340 ⁰ C is kept. 16. The method according to claim 15, characterized in that (
lies. net that the temperature is about 150 ⁰ C to 200 ⁰ C 17. The method according to claim 13, characterized in that the pressure in the extruder cylinder to more than 14 bar is kept. 18. The method according to claim 17, characterized in that the pressure is between 14 and about 350 bar lies. 19. The method according to claim 17, characterized in that the pressure is between about 52 to 105 bar lies. 20. The method according to claim 13, characterized in that the substance in the cylinder is about 15 to 200 Seconds. 21. The method according to claim 20, characterized in that this period is about 30 to 60 seconds amounts to. 22. The method according to claim 13, characterized in that the effective dimensions of the nozzle in Can be set as a function of the pressure conditions in the cylinder. 23. Extruder, characterized by: - an elongated cylinder having a material inlet at one end and, at the other, downstream end thereof has a material outlet; - an elongated one, in the cylinder around an axis rotatable screw for conveying the stock from the inlet end to the outlet end, the Screw has: a feed zone near the inlet end of the cylinder, which is a catchy one ^; Has screw portion; - a transition zone downstream of the feed zone, which first and second helical flights has, each representing a sequence of helical sections where alternate first and second threads along the length of the transition zone and wherein the height of the first screw flight is less than the height of the second screw flight is; and - a compression zone downstream of the transition zone, which extends towards the Outlet end extends and has a twin screw screw portion, the twin screws of essentially constant Height are; and a nozzle at the outlet end of the cylinder for forming an extrusion orifice. BATH ORIGINAL