RU2174165C1 - Apparatus for manufacturing fibrous materials from thermoplastic melt - Google Patents

Abstract

FIELD: synthetic sorbents. SUBSTANCE: invention relates to manufacture of fibrous synthetic materials from thermoplastics and their mixtures including both quality industrial stock and various types domestic and industrial thermoplastic wastes. Novelty consists in that fiber formation process is carried out in paraboloid-shaped rotary reactor mounted vertically downwards, which is heated by circulating water steam flow. Invention can be most advantageously applied for production of sorbents catching crude oil and petroleum products as well as a series of heavy metals from water. EFFECT: significantly reduced power consumption and improved quality of fibers. 2 cl, 2 dwg

Description

 The invention relates to the production of fibrous synthetic materials from thermoplastic substances and mixtures thereof, including both high-quality industrial raw materials and various types of household and industrial wastes of thermoplastic materials.

 The invention with the greatest effect can be used to obtain sorbents that trap oil and oil products from water, as well as a number of heavy metal ions.

 The process of producing a fibrous thermoplastic material is carried out, as a rule, in two stages: obtaining a melt and forming the fiber. Known devices for producing fibrous materials that implement methods according to which thermoplastic materials are first melted and then fiber is formed from the melt by extruding it through spinnerets. One of such devices is known from (1). It contains a loading hopper, a feed unit, a melting grate with a heated inert gas distributor, which are made in the form of trihedra and are located uniformly along the surface of the melting grate or parallel to its base. The processed raw material is gradually warmed up to a temperature close to the melting temperature in the superlattice space of the melting lattice, and freely passes between the trihedral distributors of the heated inert gas and is treated with nitrogen. In the case of the melting grate there are nests in which heating elements are inserted. Due to this, the heated raw material melts and then enters the discharge screw, is filtered through a filter and formed into a vein or fiber.

 Using such devices, it is possible to obtain fiber only from high-quality raw materials, while ensuring a uniform supply of raw materials first to the melting grate and then melt to the unloading auger.

 Known devices in which the need for compliance with measures to ensure uniform melt passage is eliminated. These include devices for producing fiber from a melt film (2, 3). The melt film is divided into separate streams at the edge of a rotating reactor. The reactor is made in the form of a horizontally mounted rotating bowl and is divided into two parts - the inner cavity and the working surface. An energy carrier is supplied under pressure to the internal cavity of the reactor, and a melt is fed to the working surface, which is directed by centrifugal forces to the edge of the bowl. There are slotted holes on the edge. The energy carrier, passing from the internal cavity of the reactor through slit-like openings, divides the melt film into separate streams, processes them from two sides, thins and draws them into fibers. To obtain high-quality fiber using such a device, the energy carrier must have a temperature higher than the polymer degradation temperature and have a sufficiently high speed to thin and lengthen the trickles of the melt, turning them into fiber. In addition, an open bowl leads to heat loss and, consequently, a decrease in the efficiency of the process.

 It is also known a device for producing non-woven material from a polymer melt containing an extruder, a fiber-forming annular head having channels radially located and converging in the center, an air flow former that thins and cools the melt trickles to form fibers, and a finished fiber deposition unit made in the form converging in the direction of the fiber feed socket. Laying of the fibers is carried out under the action of a flat air flow supplied in the direction of extrudable melt streams (4). The presence of radially located and converging in the center of the channels also requires the use of high quality raw materials. Otherwise, the channels will become clogged with the molten mass and passage through the melt channels will be difficult. Therefore, obtaining high-quality fiber from substandard raw materials using this device becomes problematic.

 The task of reducing the quality requirements of the feedstock was solved in a device (5) containing a fiber former, a deposition unit for the finished fiber and a receiving device. The fiber former is a rotating hollow cylindrical reactor located horizontally and heated from the outside. The open part of the reactor is made in the form of a diverging cone, closed by a fixed conical cover, installed in such a way that between the lateral surfaces of the diverging cone and the cover a slit gap of 15 ... 20 mm is formed. Additionally, on the inner surface of the reactor, flat ribs of a triangular shape in length are installed, directed along its generatrix and facing the apex towards the melt exit, and the installation is equipped with a high-pressure ring duct.

 This solution is the closest in technical essence and is taken as a prototype.

 With the help of this device, it became possible to ensure the processing of industrial and household waste thermoplastic materials while increasing the yield of high-quality fibrous material. The practical implementation of the prototype revealed a number of significant drawbacks of the proposed fiber former. With the cylindrical shape of the reactor, it is almost impossible to carry out uniform heating of its wall and bottom with conventional heating elements. Therefore, the temperature of the bottom of the reactor and the edge is always less than its walls. Naturally, the melt will accumulate in the corners between the wall and the bottom, forming the so-called stagnant zone, where the melt cools and adheres to the bottom and the part of the wall adjacent to the bottom. The formation of stagnant zones reduces the performance of the device and adversely affects the quality of the fiber. Solid polymer particles detach from this zone, are entrained by centrifugal forces together with the melt to the edge of the reactor and are carried out together with the fiber, which impairs the properties of the fiber (the fiber will be inhomogeneous with thickenings or with the inclusion of solid unrefined particles of various shapes). To clean the "stagnant zone" it is necessary to periodically stop the operation of the device and mechanically remove the adhered polymer - this reduces the performance of the installation. Or increase the heating of the wall of the reactor, and this leads to a significant overheating of the melt film. Another disadvantage of the fiber former is that a little more than 30% of the input thermal energy is spent directly on heating the film. The remaining energy released by the heater, due to radiation exchange, is spent on heating the internal environment of the reactor and the surrounding air. In addition, due to reradiation between the heater and the reactor, overheating of the heating elements and the melt film is observed in the central part of the reactor. This can lead, on the one hand, to the combustion of heaters, and, on the other hand, to a significant or complete burnout of the polymer. With a uniform distribution of heater power in the radial and axial directions, the bulk of the heat accumulates in the upper part of the heater. In this case, overheating and combustion of the heating elements is also possible.

 The basis of the present invention is the task of reducing the specific energy costs of obtaining fiber, increasing the reliability of the device and improving the quality of the fiber.

 The problem is solved in that the known device containing a heated rotating hollow reactor with a lid and a cone-bent edge and an annular high pressure duct additionally contains a steam generator, a casing in which the reactor is placed, and a rotating melt diffuser installed inside the reactor in its upper part attached to a rod with vertical movement and forming an adjustable annular inlet, the melt diffuser is made of two motionless soy The parts are interconnected: the upper part is a truncated cone, and the lower one is a plate with a diameter exceeding the larger base of the cone, which is connected to the flat surface of the cone with this base, and the reactor is mounted vertically and made in the form of a paraboloid formed by the rotation of the parabola around its axis, with an aperture at the apex and an expanding part directed downward, with flat ribs only at the bottom of the reactor, the inner surface of the casing repeating the surface of the reactor, and vapor Tel its input and output connected to the cavity between the housing and the reactor, forming a closed steam circuit. In addition, the cover is made in the form of a disk mounted at the level of flat ribs, and the ribs are connected to the generatrix of the disk.

The present invention differs from the prototype in that:
- the reactor is installed vertically;
- additionally, inside the reactor in its upper part there is a rotating melt diffuser attached to a rod with the possibility of vertical movement;
- the diffuser is made of two parts motionlessly interconnected: the upper part is a truncated cone, and the lower one is a plate with a diameter greater than the larger base of the cone, which this base is connected to the flat surface of the plate;
- the reactor is made in the form of a paraboloid formed by the rotation of the parabola around its axis, with a hole in the apex and an expanding part directed downward;
- flat ribs are available only in the lower part of the reactor;
- the reactor is equipped with a casing, the inner forming surface of which repeats the surface of the reactor;
- additionally, the device comprises a steam generator, which is connected with its inlet and outlet to the cavity between the casing and the reactor, forming a closed steam circuit;
- the cover is made in the form of a disk mounted at the level of flat ribs, and the ribs are connected to the generatrix of the disk.

 Due to the placement of the reactor vertically and in the form of a paraboloid formed by the rotation of the parabola around its axis, with an aperture at the apex and an expanding part directed downward, the formation of stagnant zones is eliminated, where the melt can accumulate and solidify. The reactor has virtually no bottom and is a passage with openings at the ends. The upper hole through which the melt enters is partially blocked by the diffuser, forming an annular inlet. In addition, the flow rate of the melt film increases due to the creation of a vertical component of the speed of movement of the melt film. This leads to an increase in device performance. The implementation of the reactor in the form of a paraboloid of rotation while maintaining the height of the reactor and the diameter of the outlet (in comparison with the prototype) can significantly reduce its internal volume, and therefore the amount of thermal energy required for heating this volume. It is obvious that both heat losses will be minimal and specific heat costs as well.

 The uniformity of the heating of the walls of the reactor is achieved by the fact that through the cavity formed by the walls of the reactor and the casing, a high-temperature stream of water vapor is constantly circulating. This stream equally and uniformly heats the entire reactor, including the bent edge. Therefore, the melt film will have a constant temperature and thickness, and the fiber will have the same diameter along its entire length and will not contain unmelted particles.

 In FIG. 1 shows a general view of the device. In FIG. 2 is a view B in FIG. 1.

 A device for producing fibrous materials from molten thermoplastics (Fig. 1) includes an installed vertically rotating hollow reactor 1 made in the form of a paraboloid formed by the rotation of the parabola around its axis, in which the open part is made in the form of a diverging cone 2, and at the top there is a hole 3 for melt inlet. Flat ribs 4 are installed on the inner surface of the reactor in front of the bent edge. The reactor is placed in a casing 5, the surface of which repeats the surface of the reactor 1 with the formation of a cavity 6. This cavity is connected with its upper part to the outlet of the steam generator 7, and the lower one to its entrance. So, a closed steam circuit is formed. The arrows indicate the movement of water vapor. It is possible to connect the upper part of the cavity with the inlet of the steam generator, and the lower one with its output. In this case, the movement of water vapor will be carried out in the opposite direction. Inside the reactor 1, in its upper part, a rotating melt diffuser 8 is mounted, mounted on a vertically movable rod 9, forming an adjustable annular inlet 10. The diffuser 8 consists of two parts that are motionlessly interconnected: the upper part is a truncated cone 11, and the lower one plate 12 with a diameter greater than the larger base of the cone, which this base is connected to the flat surface of the plate. The bottom of the reactor is closed by a cover made in the form of a disk 13. Flat ribs 4 are connected to the forming surface of the disk 13. The reactor 1 is mounted on the end of the hollow shaft 14 mounted in bearings 15 located in the cooled case 16. A driven pulley 17 is installed on the other end of the shaft 14 for transmitting rotation, for example, from an induction motor (not shown in the figure).

 A device for producing fibrous materials from molten thermoplastics works as follows.

 Before operation, the reactor 1 is heated to operating temperature by supplying circulating water vapor to the cavity 6. Since the water vapor stream has a constantly high temperature and speed, heating of the reactor wall over its entire surface is uniform. The heat flux from the hot surface of the reactor is transferred inside it, creating and maintaining the necessary temperature in the entire internal volume. Thus, a uniform temperature field is formed over the entire surface of the reactor.

 After the device is ready for operation, the reactor is rotated at a given angular velocity. Then through the hollow shaft 14 and the annular hole 10 serves the melt of the polymer material. The melt first enters the conical part 11 and flows down it, acquiring additional acceleration due to the rotation of the plate 12. The plate is essentially a storage ring where the melt is evenly distributed over its entire perimeter. Since the plate has the opposite taper (the edges of the plate are raised), an additional sealing force is created and the melt, acquiring the necessary speed and force, moves in the form of a uniform film to the periphery. Having reached the edge of the plate, the melt film breaks down, falls on the inner surface of the reactor 1 and moves downward, acquiring additional acceleration of gravity, and reaching the part of the reactor where the flat ribs 4 are located, the melt film dissects into separate streams, which, tearing off the edge of the conical part 2 reactors form thin fibers. An annular duct 18 directs the resulting fibers into the drive (not shown in the figure).

Sources of information
1. SU A. p. N 1236020, Ml. D 01 D 1/04, 1984.

 2. GB Patent N 1265215, Ncl. C 1 M, 1972.

 3. SU A. p. N 669041, Ml. D 01 D 5/08, 1977.

 4. RU Patent N 2061129, Mcl. D 04 H 3/16, 1996.

 5. RU Patent No. 2117719, Mcl. D 01 D 5/08, D 04 H 3/16, 1998.

Claims (2)

 1. Device for producing fibrous materials from molten thermoplastics, containing a heated rotating hollow reactor, on which flat ribs are installed on the inner surface, and the open part is made in the form of a diverging cone, a cover and an annular duct, characterized in that it further comprises a steam generator, a casing, in which the reactor is placed, and a rotating melt diffuser mounted inside the reactor in its upper part, attached to a rod that can vertically move and reverse The adjustable melt diffuser is made up of two parts that are motionlessly interconnected: the upper part is a truncated cone, and the lower one is a plate with a diameter greater than the larger base of the cone, which is connected to the flat surface of the plate with the reactor installed vertically and made in the form of a paraboloid formed by the rotation of the parabola around its axis, with an aperture at the apex and an expanding part directed downward, with flat ribs only at the bottom part of the reactor, the surface of the casing repeats the surface of the reactor, and the steam generator with its input and output is connected to the cavity between the casing and the reactor, forming a closed steam circuit.  2. The device according to p. 1, characterized in that the cover is made in the form of a disk mounted at the level of flat ribs, while the ribs are connected to the generatrix of the disk.

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