WO2000029649A1

WO2000029649A1 - Disperser

Info

Publication number: WO2000029649A1
Application number: PCT/US1999/024728
Authority: WO
Inventors: Viktor Mikhailovich Drobosyuk
Original assignee: Pragmatic Vision, Inc.
Priority date: 1998-11-16
Filing date: 1999-10-25
Publication date: 2000-05-25
Also published as: AU1220400A; RU2154706C2

Abstract

A disperser comprises a housing (1), a rotor (2) that is accommodated within the housing, a plurality of accelerating blades (5) disposed on both sides of the rotor. Input (4) and output (6) channels coaxially located on opposite sides of the rotor, and a core barrel (8) having tangential slots (9) that is located coaxially between the cylindrical wall of the housing and faces edges of the rotor's accelerating blades. The core barrel and housing together form an annular cavity (10) that is in communication with a tangential channel (11) intended for supplying air. The output channel is in the form of a cylindrical tube of continuous cross-section containing partitions installed radially along said tube. Application of the disperser permits dispersal of materials and production of a uniform swirl-free flow of aerosuspension. The disperser produces a flow of aerosuspension having a uniform distribution of particles at the device output, and decreases the probability of collisions that can result in bundling, or coagulation, of dispersed particles.

Description

DISPERSER

FIELD OF THE INVENTION

The present invention relates to devices for grinding fibrous materials, and, more particularly to a device that can be used for producing an aerosuspension of fibers.

BACKGROUND OF THE INVENTION

Centrifugal mills having various configurations are known. One such centrifugal mill comprises a housing having an intake manifold and discharge unit. A rotor in the form of a disk having beaters attached thereto defines an annular channel with the inner side surface of the housing. A breaking ring containing slots is tangentially located to the inner surface of the housing in the spinning direction of the rotor. See, for example, USSR Author's Certificate #1636043, B 02 C 13/08, published 03/23/91 , Official Bulletin #11. A rotor shaft is installed vertically, and an impeller is mounted to the bottom part of the rotor in the centrifugal mill. A discharge unit, located on the opposite end of the device from the intake manifold, envelopes the impeller. The inner space of the annular channel between the side surface of the housing and rotor is configured such that it is no greater than the total space of the slots in the breaking ring plus the space of the slot between the face surfaces of the rotor and the breaking ring.

However, when using this mill for breaking fibrous materials into individual fibers, undesirable phenomenon occurs wherein fibers stick together due to insufficiently intensive agitation by the airflow in the areas of dispersion and discharge. A device for grinding, which is believed to be the closest to the present invention in its engineering essence is a device comprising a cylindrical housing having a rotor therein. The rotor is configured as a disk with accelerating blades and secured on a shaft in such a way that spinning is possible. Input and output channels are located coaxially about the axis of the rotor spinning (the output channel has the shape of an annulus which envelopes the input channel and which is in communication with a suction cyclone). USSR Author's Certificate #1629094, B 02 C 13/26, published 02/23/91 , Official Bulletin #7. The rotor's accelerating blades are secured on the rotor radially on the side of output channel. The device also includes a core barrel having tangential slots, which is located coaxially between the cylindrical wall of the housing and edges of rotor's accelerating blades and which forms, together with the housing, an annular cavity that is in communication with a tangential channel destined for air supply. The tangential slots have axes of symmetry tilted at an angle of 7- 10 degrees to a tangent line passed to an inner wall of the core barrel at a point located at an equal distance from two adjacent slots.

Due to the fact that the output channel in this device is annular, heavily swirled flow of an aerosuspension of ground material is produced at the output of the device when the latter is used for manufacturing various products, in particular, paper by an aerodynamic method.

SUMMARY OF THE INVENTION

The present invention provides a disperser enabling one to obtain continuous and uniform flow of aerosuspension of fibers. The disperser of the present invention comprises a housing and a rotor that rotatably mounted within the housing for rotation about an axis of rotation. A plurality of cutting members are attached to the rotor. An input channel is located on a first side of the rotor, while an output channel located on a second side of the rotor that is opposite to the first side. A core barrel located coaxially between the housing and edges of the plurality of cutting members. Further, the core barrel contains a plurality of tangential slots therein. The core barrel and the housing together form an annular cavity that is in fluid communication with a tangential channel for supplying air to the disperser.

According to one embodiment of the invention, the output channel can be constructed in the form of a cylindrical tube having a continuous cross-section and containing radially disposed partitions along the tube.

According to another embodiment of the invention, each of the plurality of cutting members can be in the form of an accelerating blade configured for mounting on the rotor such that a first portion of the accelerating blade is positioned on the first side of the rotor, and a second portion of the accelerating blade is positioned on the second side of the rotor.

To simplify the design of the device, the accelerating blades on both sides of the rotor can be constructed as single blades attached to the rotor.

According to another aspect of the invention, a method of grinding fibrous materials comprising the steps: feeding the fibrous material through an input channel of a disperser; grinding the fibrous material using a rotor containing a plurality of blades; supplying a flow of air to the rotor during the step of grinding; and removing particles of the fibrous material that have been ground to a predetermined size using the supplied flow of air.

The engineering result attained by the present invention is determined by the fact that input and output flows of the processed material are separated in a space within the device, which makes it possible to produce a continuous flow of aerosuspension of ground material at the output, for example, aerosuspension of cellulose fibers. To provide feeding of a material to be ground into the intensive grinding zone, extra accelerating blades are installed on the rotor disk on the side of the input channel. To quench circular motion of the outgoing flow of aerosuspension of fibers, the output channel is made as a cylindrical tube of continuous cross-section with partitions installed radially along the tube.

BRIEF DESCRIPTION OF DRAWINGS

Fig. 1 is a side elevational view of a disperser made in accordance with an embodiment of the present invention.

Fig. 2 is a sectional view of the disperser taken along line A-A of Fig. 1.

Fig. 3 is a sectional view of the disperser taken along line B-B of Fig. 1.

DETAILED DESCRIPTION OF THE INVENTION

Referring to Figs. 1 - 3 , a disperser according to an embodiment of the present invention comprises a housing 1 which accommodates a rotor therein. The rotor preferably comprises a rotor disk 2 fitted to a shaft 3. Cutting members such as, for example, first and second accelerating blades, are attached to the rotor. The first accelerating blades 5 are fixed to the rotor 2 on the side of an input channel 4, and the second accelerating blades 7 are fixed to the rotor 2 on the side of an output channel 6. A core barrel 8 having tangential slots 9 (Fig. 3) and form, together with the housing 1 , an annular cavity 10. The core barrel 8 is located between the cylindrical wall of the housing 1 and faces the edges of blades 7. The cavity 10 is in fluid communication with tangential channel 11 for supplying air to the device. Longitudinal partitions 12 are also installed in output channel 6 (Fig. 2).

The device operates in the following manner. A material to be dispersed (i.e. ground pulp) is fed into the disperser together with an airflow through the input channel 4. Then the material arrives at the spinning rotor 2. Under the action of centrifugal force, pulp particles move to the periphery of the rotor 2 and arrive in the annular gap between core barrel 8 and blades 7. Concurrent with this process, a stream of air is supplied to the annular gap through channel 11 , cavity 10, and slots 9 of core barrel 8. As the result of the above, a suspended layer of ground pulp is produced in the annular gap between the core barrel 8 and the edges of blades 7. Because the particles in the suspended layer intensively strike against the blades 7 and core barrel 8, separation of pulp particles occurs.

This process continues until pulp particles are separated into individual fibers. Then light-weight fibers are carried by an air stream fed through slots 9 of the core barrel 8 into the output channel 6. Heavy-weight pulp particles (i.e. those that were not separated into individual fibers) remain in the dispersion zone due to the action of the centrifugal force until they are separated into individual fibers, at which point the force of aerodynamic resistance to the air stream will exceed the centrifugal force, and the individual fibers will be carried away into output channel 6. The degree of dispersion is determined primarily by the spin speed of the rotor, pressure of the air supplied through channel 11 , specific weight, and other physical parameters of the material being dispersed.

To prevent swirling of the output flow of the aerosuspension, output channel 6 is made as cylindrical tube of continuous section, and longitudinal separating partitions 12 are installed in the tube.

Thus, the present invention permits one to accomplish dispersion of the materials, and produce a uniform, swirl-free flow of aerosuspension. Such aerodynamic parameters of the flow of aerosuspension decrease the probability of collision and sticking together of dispersed particles, thus enabling one to obtain a flow of aerosuspension offering uniform distribution of particles at the device output.

While this invention has been described in connection with what is presently considered to be the most practical and preferred embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.

Claims

WHAT IS CLAIMED IS:

1. A disperser comprising:

a housing;

a rotor rotatably mounted within said housing for rotation about an axis of rotation;

a plurality of cutting members attached to said rotor;

an input channel located on a first side of said rotor;

an output channel located on a second side of said rotor that is opposite to said first side; and

a core barrel located coaxially between said housing and edges of said plurality of cutting members, said core barrel containing tangential slots therein;

wherein said core barrel and said housing together form an annular cavity in fluid communication with a tangential channel for supplying air to said disperser.

2. The disperser of claim 1 , wherein said output channel comprises a cylindrical tube having a continuous cross-section and containing radially disposed partitions along said tube.

3. The disperser of claim 1 , wherein each said plurality of cutting members comprises a pair of accelerating blades respectively mounted on the first and second sides of said rotor.

4. The disperser of claim 1 , wherein each said plurality of cutting members comprises an accelerating blade configured for mounting on said rotor such that a first portion of said accelerating blade is positioned on the first side of said rotor, and a second portion of said accelerating blade is positioned on the second side of said rotor.

5. A method of grinding fibrous materials comprising the steps:

feeding the fibrous material through an input channel of a disperser;

grinding the fibrous material using a rotor containing a plurality of blades;

supplying a flow of air to the rotor during the step of grinding; and

removing particles of the fibrous material that have been ground to a predetermined size using the supplied flow of air.

6. A disperser comprising:a housing;

a rotor that is accommodated in said housing, and made as a disk

including accelerating blades and fitted to a shaft in such a way that

spinning is possible;

input and output channels located coaxially about a spin axis of said rotor

said rotor's accelerating blades being secured on a rotor disk predominantly radially on the side of said output channel;

and a core barrel including tangential slots and located coaxially between said cylindrical wall of the housing and faces edges of said rotor's accelerating blades and forms; together with said housing an annular cavity that is in communication with a tangential channel intended for air supply;

wherein said input channel is located on a side of said rotor disk that is opposite to the one where said output channel is located, said rotor disk includes extra accelerating blades on the side of said input channel, said blades being secured predominantly radially, and said output channel being made in the form of a cylindrical tube of continuous section with partitions installed radially along said tube.