CN1165657C - Apparatus and method for feeding an aerosuspension stream onto a forming wire of a paper machine - Google Patents

Abstract

An apparatus for delivering a fibrous aerosuspension stream onto a forming wire of a paper machine includes a cylindrical body, a plurality of inlet channels, and an outlet channel. A rotor having a plurality of rotor blades mounted thereto is mounted in the cylindrical body. The aerosol stream enters the device from a plurality of diffusers through an inlet channel. The rotor mixes the aerosol flow so that the output channel provides an aerosol flow having fibers uniformly distributed across the width of the forming wire.

Description

Apparatus and method for delivering a fibrous aerosuspension stream to a paper machine forming wire

field of invention

This invention relates to apparatus for the aerodynamic manufacture of various types of paper from fibrous material and, more particularly, to apparatus that can be used in the paper industry to deliver a stream of fibrous aerosuspension onto a forming wire.

Background of the invention

The aerodynamic process of papermaking can be roughly divided into the following main stages: grinding of fibrous material, its diffusion (i.e. separation of the ground material into individual fibers and formation of an air suspension of fibers), formation of a fiber layer on the forming wire, Pressed and dried. In order for the paper web leaving the paper machine to be uniform in thickness and width, the uniformity of the fibers placed on the forming wire must meet high demands. This is especially difficult to achieve when producing wide paper webs. In this case in order to maintain a high productivity of the process, some means of separating the fibrous material into individual fibers (i.e. diffusers) are used for delivering the air suspension stream to a means which divides the fibers in the width of the formed web. Form a single air-suspended stream evenly distributed on the surface.

Apparatus for drying an air suspension of fibrous material to form a web are well known. One such device comprises a chamber with a perforated bottom which houses a rotor with a housing and brushes. The chamber is formed with inlet and outlet fittings and includes a concentrator mounted on the inlet fitting. See, for example, Soviet author's certificate No. 1110845, 3 D 21 H 5/26, published in Information Bulletin No. 32, August 30, 1984. The body of the concentrator is curved radially from the delivery side in the direction of delivery and is equipped with a waste collection hopper mounted on its larger radial wall; said body also forms a partition dividing it into two parts for To convey the fiber flow and remove air, the above-mentioned partitions are installed on the fiber output side. The air removal section is equipped with some separating vanes. The concentrator forms an additional section mounted on the side from which the fibrous aerosuspension is conveyed, which additional section is provided with a diverting baffle.

As the air suspension stream enters the concentrator, the concentrator moves the large particles to a waste collector and separates the air suspension stream into a concentrated fiber stream and an air stream. The air is removed and the air suspension stream is delivered to the rotor with brushes. Further fracture of the fiber sheet occurs when the brush interacts with the perforated bottom. The separated fibers are deposited on the forming wire through the perforations at the bottom. However, due to the close proximity of the diffuser body represented by the rotor with brushes to the forming wire, the structural uniformity of the produced web is affected because the amount of fiber aerosuspension passing through the bottom opening of the chamber per unit time cannot be precisely controlled. The device is also generally not capable of producing a uniform air-suspended stream at increased speeds of the aerodynamic forming process to make wide webs, i.e. converging the streams from several diffusers into a uniform distribution of fibers across the width of the formed web. Single stream of air suspension.

Another apparatus for forming dry webs includes a cylindrical fiber delivery conduit having a longitudinal slot for delivering dispersed fibers onto a continuous forming wire. See, for example, Soviet author's certificate No. 1154400, 4D 21 H 5/26, published in Information Bulletin No. 17 of May 7, 1985. The slotted section of the pipe is tapered in the direction of web movement. The pipe is arranged at an angle less than 90 degrees relative to the axis of the network, and its inclination angle is adjustable. The tube is provided with a means for uniform distribution of the fibers across the width of the wire in the form of a series of slotted rings along the tube, each ring forming a catcher. A suction box is placed under the mesh to allow controlled vacuum generation. Uniform deposition of fibers across the width of the web requires that the same amount of fiber be deposited on the web per unit length of tubing at the beginning and end of the slots. This condition is provided by the pipe taper. An adjustment ring that controls the opening of the slot at any point along the length of the pipe is used to fine-tune the flow. The device described above is simple in structure, although it is labor-intensive to adjust the device to different forming speeds in each particular case. Additionally, the device does not provide a uniform flow of fibers from several diffusers.

The Soviet author's certificate No. 746007, 2 D21 D 1/34, published in the No. 25 Information Bulletin on July 7, 1980, discloses a method that is considered to be the closest to the claimed invention for fiber separation of fibrous materials installation. The device consists of a cylindrical body, a rotor, and a centrally nested duct designed with disk-supporting baffles. The baffles and discs form an annular channel extending along the axis of the body through which the fibrous aerosuspension from each diffuser is conveyed. Concentric slotted rings are secured to both sides of the disc. The rotor consists of two support discs supported by their bearings on the outer tube of the stator. The support disc is interconnected with blades fixed around its circumference to form a fan. The fan blades form the rotor disk to which they are attached. The discs have concentric grooved rings on their sides. The concentric rings of the rotor are coaxial with the concentric rings of the stator. A screen is mounted around the rotor at a distance therefrom.

The unit is fitted with connectors for delivery and removal of fibrous aerosuspension. The device combines the function of diffusion with the creation of an evenly distributed flow of aerosuspension of fibers across the width of the formed web. The aerosuspension flow from each diffuser is conveyed through the channel into the rotor. The stream driven by the rotor blades collides with the rotating ring of the rotor and the stationary ring of the stator in an alternating manner, which determines the process of diffusion.

The fully diffused fibers are conveyed through a screen located in the device where they pass through an opening in the bottom of the body to the forming wire of the paper machine. Such a structure provides uniform deposition of fibers across the width of the wire so that papermaking equipment can be fabricated with virtually any acceptable width required for papermaking. However, as mentioned above, combining the diffusion function with the distribution of the fibrous aerosuspension across the width of the forming wire reduces the structural uniformity of the formed web and complicates the overall device structure. The presence of the strainer significantly reduces the productivity of the device.

SUMMARY OF THE INVENTION

Therefore, the present invention provides a device capable of improving the uniformity of the structure of the formed web and having a simple structure.

According to the invention, a device for delivering a fibrous aerosuspension stream to a forming wire of a paper machine comprises a cylindrical body comprising a plurality of input channels for receiving a fibrous aerosuspension stream along the The length of the cylindrical body is distributed axially; and an output channel for guiding the received air-suspension flow out of said cylindrical body. A rotor having an outer surface and an axial length is mounted within the cylindrical body. A plurality of rotor blades are mounted to the rotor in a radial configuration, each rotor blade having an axial dimension. In addition, the input and output channels are located outside this cylindrical body and are oriented tangentially with respect to the direction of rotation of the aforementioned rotor.

According to a specific embodiment of the invention, the input channel can be shaped as a diverging-converging channel that diverges axially and converges radially relative to the cylindrical body. Each diverging-converging channel has a diverging portion axially oriented relative to the cylindrical body, and a converging portion radially oriented relative to the cylindrical body. According to such an embodiment, the stream of air suspension may be distributed substantially axially before entering the cylindrical body.

According to another embodiment of the invention, the output channel may comprise a bend at the outlet of the cylindrical body. The function of this bend is to divert the output channel in a direction opposite to the direction of rotation of the aforementioned rotor.

The rotor blades can be made such that their axial dimension does not exceed half (1/2) of the rotor length. In addition, the vanes are preferably arranged in an alternating sequence on the rotor surface to improve mixing of the air suspension.

The input and output channels are located outside the body and are tangential to the direction of rotation of the rotor, allowing the flow of air suspension from several diffusers to be freely conveyed into the active mixing zone formed in the cylindrical body by the rotation of the rotor. The diverging-converging shape of the input channel further axially redistributes the flow of air suspension entering the cylindrical body, thereby accelerating the mixing process. In addition, if a bend is provided at the outlet of the body, it is prevented that the fiber tufts from the air-suspended stream reach the output channel and are deposited on the forming wire. Specifically, the fiber tufts are carried away by the recirculating air suspension flow and mixed again by the rotor. If the blades are less than half the length of the rotor and are arranged in an alternating sequence on the rotor surface, conditions are created for further redistribution of the aerosuspension flow and better mixing of the aerosuspension flow is achieved. The air-suspension stream conveyed from the output channel to the forming wire is thus characterized by a uniform distribution of fibers across the width of the formed web.

Brief description of the drawings

Figure 1 is a perspective view of an apparatus for delivering fibrous aerosuspension according to one embodiment of the present invention.

Figure 2 is a perspective view of an apparatus for delivering fibrous aerosuspensions according to another embodiment of the present invention.

Figure 3 is a perspective view of an embodiment of a rotor for use with the device for delivering a fibrous aerosuspension.

Detailed description of the invention

1 and 2, the device of the invention comprises a cylindrical body 1; an input channel 2 extending tangentially in the direction of rotation of a rotor 3 having bearing blades 4 on its outer surface; and an output channel 5. The rotor 3 has an axial length measured in a direction parallel to the axis of rotation of the rotor. Each blade 4 has an axial dimension parallel to the axial length of the rotor 3 . Preferably, the axial dimension of the blades 4 is not greater than half of the axial length of the rotor. The input channel 2 can be made into the shape of a diverging-converging channel. In addition, as shown in FIG. 2 , the output channel 5 can be diverted in a direction opposite to the direction of rotation of the rotor 3 by means of a bend 6 at the outlet of the cylindrical body 1 . Alternatively, as shown in FIG. 1 , the output channel 5 may be oriented in the same direction as the rotation of the rotor 3 .

The operation of the apparatus will now be described with reference to Figures 1-3. A fan (not shown) delivers the air suspension flow from a diffuser (not shown) to the input channel 2 of the device. If the input channel 2 is made into the shape of a diverging-converging channel as shown in FIG. 2 , the transported aerosuspension flow converges along the radial direction of the cylindrical body 1 and expands along its axial direction. This redistribution results in a substantially axial distribution of the aerosuspension flow and delivery into the space between the body 1 and the rotor 3 .

As the air-suspension stream travels in the cylindrical body 1 , it reaches the co-acting mixing zone created by the vanes 4 arranged on the rotor 3 (see FIG. 3 ). The blades 4 draw a portion of the total flow into the rotating (or circulating) flow around the rotor 3 . A static pressure drop created by the blades 4 creates an additional recirculation flow represented by the inter-blade vortices which enhances the mixing of the air-suspended fibers. If the outlet channel 5 forms a bend 6 as shown in FIG. 2 , the deflection of the flow of the air suspension in the bend 6 caused by centrifugal force prevents possible fiber tufts from entering the outlet channel 5 . These fiber tufts are carried away by the circulating flow, broken up by the blades 4 of the rotor 3 and mixed again.

Thus, an air-suspended flow with a uniform distribution of the fibers over the entire width of the forming wire is produced by relatively simple means. This stream enables the formation of wide paper webs with improved uniformity.

While the invention has been described in connection with what are 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 covers all aspects included within the spirit and scope of the appended claims Various modifications and equivalent settings.

Claims (8)

1. one kind is used for fiber air suspension logistics is transported to device on the forming net of paper machine, and this device comprises:

One cylindrical body (1), this cylindrical body comprise a plurality of input channels (2) that are used to receive fiber air suspension logistics, and described input channel (2) axially distributes along the length of described cylindrical body (1); The output channel of guiding away from described cylindrical body (1) with an air suspension logistics that is used for to be received (5);

One is installed in the rotor (3) in the described cylindrical body (1), and described rotor (3) has an outer surface and an axial length; And

A plurality ofly be installed to rotor blade (4) on the described rotor (3) with radial arrangement, described rotor blade (4) has an axial dimension;

It is characterized in that described a plurality of input channels (2) and described output channel (5) are positioned at cylindrical body (1) outside, and tangentially directed with respect to the direction of rotation of described rotor (3).

2, device as claimed in claim 1, it is characterized in that, described input channel is made the shape of diffusion-converging passage, and this diffusion-converging passage has diffusion part and with respect to a described cylindrical body radially directed convergent portion directed vertically with respect to described cylindrical body.

3, device as claimed in claim 1 is characterized in that, described output channel comprises that one is positioned at the bend in the exit of described cylindrical body, and described bend makes described output channel along the directional steering opposite with the direction of rotation of described rotor.

4, device as claimed in claim 1 is characterized in that, described output channel is along the direction of rotation orientation of described rotor.

5, device as claimed in claim 1 is characterized in that, described rotor blade is fixed with alternating sequence.

6, device as claimed in claim 1 is characterized in that, the axial dimension of described rotor blade is no more than half of rotor axial length.

7, device as claimed in claim 1 is characterized in that, described a plurality of input channels comprise two input channels.

8, a kind of being used for is transported to method on the forming net of paper machine with fiber air suspension logistics, comprises the following steps:

From a plurality of diffusers the air suspension logistics is received as the arbitrary described transport of claim 1-7, the number of diffuser is corresponding with the number of the input channel of described transport (2);

By the rotor (3) that is installed in the described transport air suspension logistics is mixed;

Make the output channel (5) of mixed air suspension logistics by described transport; And mixed air suspension logistics is deposited on the forming net.

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