JPH07850A - Sieve's vibration frequency controlling system for vibration sieve for coal-water slurry - Google Patents

Abstract

PURPOSE:To effectively prevent the deterioration of wet-way sieving function and surely separate coarse particles from coal-water slurry by activating the vibrating state of a sieving face of a vibrating sieve. CONSTITUTION:A vibrating sieve 10 performs wet sieving of coal-water slurry and sieving face of the vibrating sieve 10 is connected to an oscillator 18 through a transmitting element 16 and the vibrating sieve 10 is provided with a vibration freuquency controlling means to detect the frequency of the sieving face and control the number of revolution of the oscillator 18 to vibrate the sieving face at a frequency near the resonance point.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a screen surface frequency control structure of a vibrating screen used for separating coarse particles in a coal / water slurry.

[0002]

2. Description of the Related Art Coal / water slurry (hereinafter referred to as "CWM") is a mixture of finely pulverized coal and water with some additives and a coal concentration of 60% by weight or more, and can be directly burned. Since it is a fuel, it is required to reduce the content of coarse particles of 150 μm or more in order to satisfy its flammability, transportability and storability. In order to remove particles, a wet sieving method using a vibrating screen is usually used.

In the above wet sieving method, high-concentration CWM is supplied to the upper end of an inclined vibrating sieve, and high-velocity vibration with small amplitude is applied to the surface of the sieve in the normal direction, whereby the high-concentration CWM is obtained. Is sieved while descending on the surface of the sieve while repeating leaps and slips, and is separated into a high-concentration coarse grain CWM which is an on-sieving product and a desired high-concentration fine grain CWM which is an under-sieving product. Are discharged from the lower end of the vibrating screen.

In the above-mentioned wet sieving operation, since the mesh opening of the sieve is very small, the CWM having high viscosity adheres to the sieve surface as it moves on the sieve surface, and with the progress thereof, the sieve mesh Although the number of openings may be reduced and finally the openings may be closed, it may become impossible to separate coarse particles from the CWM.
This is generated by reducing the vibration state, that is, the amplitude and the frequency, in the plane in the direction normal to the screen surface as the CWM moves (Japanese Patent Publication No. 4-23585).
Issue). In this type of vibrating screen, in order to vibrate the screen in the plane in the direction normal to the screen, the screen is connected to an oscillator via a transmitter.

[0005]

However, since the above-mentioned conventional diaphragm / vibrating structure for a coal / water slurry vibrating screen does not have a screen surface frequency control structure, a CWM exhibiting high viscosity moves on the screen surface. In this case, the adhesion between the CWM and the opening of the sieve surface is increased to reduce the motion state and the vibration state of the sieve surface, the wet sieving performance of the vibrating sieve is deteriorated, and the coarse particles from the CWM are removed. There is a risk that separation will be impossible.

The present invention has been made in order to solve the above-mentioned problems of the prior art, and activates the vibration state in the plane of the vibrating screen in the normal direction to the screen surface of the CWM. Coal that can reduce the adhesion, effectively prevent the deterioration of the wet sieving performance of the vibrating screen, and ensure the separation of coarse particles from the CWM
An object of the present invention is to provide a screen surface frequency control structure of a vibration screen for water slurry.

[0007]

In order to achieve the above object, the present invention provides a vibrating screen for wet-sieving coal / water slurry, the vibrating screen including an oscillator through a transmitter on the screen surface. And a frequency control means for detecting the frequency of the screen surface and controlling the rotational speed of the oscillator to vibrate the screen surface at a frequency near the resonance point. Is.

[0008]

By doing so, the unbalanced weight of the oscillator is rotated to generate a periodic exciting force, which is transmitted to the sieve surface via the transmitter, and in the plane in the normal direction of the sieve surface. In order to vibrate at the required amplitude and frequency, and to detect the frequency of the screen surface, and to vibrate the screen surface at the frequency near the resonance point corresponding to the natural frequency of the screen surface. Since the rotation speed of the oscillator is controlled by the output signal of the frequency control means, the vibration state of the screen surface of the vibrating screen is activated without being affected by the properties of the CWM, and the vibrating screen of the vibrating screen is activated. It is possible to effectively prevent deterioration of the wet sieving performance and ensure separation of coarse particles from the CWM.

When the screen surface is vibrated at a specific frequency, a plurality of nodal lines are formed according to the vibration mode of the screen surface, and the nodal line portion is set to the midpoint of the amplitude. Therefore, the movement of the CWM will be delayed, but if the rotational speed of the oscillator is sequentially changed with the output signal from the sequential circuit of the control circuit, the nodal line position will follow the above change and will be on the screen surface. Therefore, the sieving operation can be performed by optimizing the movement of the CWM under the frequency near the resonance point described above while eliminating the occurrence of the stagnation of the CWM.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a coal
FIG. 2 is an overall configuration diagram of a vibrating screen for water slurry, and FIG. 2 is a circuit diagram of the screen surface frequency control structure.

In FIGS. 1 and 2, reference numeral 10 denotes a vibrating screen for wet-sieving a CWM.
A screen 12 having a required opening size, for example, a screen is stretched, and the screen 12 is connected via a transmission element 16 to an oscillator 18 which operates at a variable speed, and the oscillator 18 is elastic means. It is supported on a mount 21 via 20. Then, the oscillating force of the oscillator 16 is transmitted in the normal direction of the sieve surface 12 via the transmitter 16, and the required number of oscillators 18 and the transmitters 16 are arranged on the sieve surface 12 to cause the vibration of the sieve surface 12. Is done.

Reference numeral 22 denotes a disperser, which is attached to a support member above the vibrating screen 10. The disperser 22 is a vibrating screen 16.
The dispersion shaft 24 is oriented in the width direction of the dispersion shaft 24. The dispersion shaft 24 is rotatably supported on both sides by bearings on the support member, and the rotational force is transmitted by the drive source. A plurality of dispersion members 26 are arranged at required intervals in the axial direction of the dispersion shaft 24, and the assembly of the dispersion shaft 24 and the dispersion member 26 is housed in a cylindrical supply gutter 28. ing. A supply pipe 42 for supplying the CWM to the supply gutter 28 is connected through an opening of an upper casing 40 provided at the upper part of the supply gutter 28.

A lower portion of the supply gutter 28 is provided with a supply port 30 that extends in the axial direction and is open at a position close to the bottom, and an outer periphery of the supply gutter 28 is slidable along the outer periphery of the movable cover. 32 is provided. A support shaft 34 is attached to the outside of the movable cover 32, and is attached to a pressure cylinder 38 via a connected moving rod 36.
It is slidable by the operation. The end of the movable cover 32 is made to overlap the opening of the supply port 30, and the overlap is made variable by sliding, so that the supply port 3
The opening area of 0 is variable, the CWM supply flow rate to the vibrating screen 10 can be controlled, and the mixed dispersion state of CWM can be adjusted.

Above the vibrating screen 10 is a C above the screen surface 12.
A fixed nozzle 34 is provided on the upstream side of the WM moving flow, and a plurality of moving nozzles 60 attached to an insertion / removal pipe 62 are provided on the downstream side, all of which are connected to a water supply pipe (not shown),
The cleaning water is sprayed so as to spread over the entire surface of the screen 12, so that the cleaning of the mesh can be performed automatically and efficiently.

On the other hand, a switching damper 48 is provided at the bottom of the vibrating screen 10 so that it can be opened and closed, and when the switching damper 48 is in the position (a) as indicated by the solid line, it is opened and the vibrating screen 10 is opened. The wet sieving operation is performed, and the coarse CWM which is the on-screen product is discharged from the discharge port 54 at the lower end of the vibrating sieve 10 and is continuously guided to the coarse particle passage 56, while the fine CWM which is the under-screen product is , And is directly guided to the fine grain passage 58 and conveyed to the next step.

When the sieve surface 12 of the vibrating sieve 10 is clogged, the switching damper 48 is set to the position (b) as shown by a chain line, and is closed and the supply of the CWM from the supply gutter 22 is stopped, and then the supply damper 22 is stopped. Then, washing water is sent to wash the sieve mesh with the sieve surface 12 being vibrated. In the CWM diluted by the washing, the on-screen product is guided from the discharge port 54 to the coarse grain passage 56, and the under-screen product is guided from the discharge port 54 to another passage 60 to be the CWM in the fine grain passage 58. It is prevented from being mixed.

In FIG. 2, reference numeral 70 denotes a screen surface frequency control structure, in which light from the light ray 72 vibrates at an arbitrary frequency as indicated by A as incident light 76 without using a mirror 74 or directly. The reflected light 78 from the sieving surface 12 is received by the condenser 80 through the lens 79 onto the condenser 80 to read an image, and the signal read by the condenser 80 is amplified and signaled. The converted image signal is input to the control circuit 82. Since the reflected light 78 periodically changes the light intensity with the vibration of the screen surface 12, the screen surface 1 is read by the image signal from the condenser 80 that reads the image formation.
A frequency of 2 can be detected.

On the other hand, the sieving surface 12 of the vibrating sieve 10 has an oscillator 18
Together with the vibration system, the sieve surface 12 is forcibly vibrated by the periodic exciting force generated by the oscillator 18, and when the frequency of this exciting force matches the natural frequency of the vibrating system, the sieve surface 12 becomes a resonance state. Would significantly increase the amplitude of. This natural frequency is governed by the structural parameters of the sieve surface 12, such as mass per unit area and tension per unit length.

Under the resonance condition, an excessive vibration force may be transmitted to the structure of the vibrating screen 10, causing damage to the member and making the movement of the CWM on the screen surface 12 unsmooth. Further, when the frequency ratio is far from the resonance point and is vibrated, the amplitude of the sieve surface 12 becomes small and the CW
The movement of M may be delayed. Therefore, the frequency ratio is vibrated so as to be in the vicinity of the resonance point to optimize the movement of the CWM. The frequency of the sieve surface 12 is detected and input to the control circuit 82, and the control circuit 8
2 also incorporates a reference model, and when the frequency of the oscillator 18 corresponding to the vicinity of the resonance point of the vibration system is selected as a reference input, the output frequency of the reference model corresponding to the natural frequency of the vibration system is set to the screen surface 12 The parameters of the control device are adjusted so that the detected frequency follows, and the oscillator 18 is adjusted by using the optimum control input.
Controls the frequency of rotation, that is, the rotation speed. The oscillator 18 uses an induction motor, and is connected to a variable speed drive circuit 84, for example, a VVVF inverter for variable speed drive thereof, and oscillates by operating the variable speed drive circuit 84 under the control input. The rotation speed of the machine 18 is controlled.

Therefore, the amplitude of the sieving surface 12 can be optimally increased, so that the CWM can be efficiently moved. The control characteristic can be improved by incorporating the reference model of the control circuit 82, and the model can be adjusted freely even if the natural frequency of the vibration system inevitably changes. Therefore, the rotation of the oscillator 18 is prevented. Unlike the direct control method, the numerical control can improve control accuracy and stability.

The sieving surface 12 forms a flat membrane fixed to the surrounding sieving frame, and when the sieving surface 12 is vibrated at a specific frequency, it is generated under the structural parameters as described above. The motion of the gyro presents a vibration system with a specific vibration mode, and a plurality of nodal lines are formed by the combination of the vibration modes. Then, each moves in the opposite direction and vibrates at a specific frequency. When changing the number of revolutions of the oscillator 18, the screen surface 12 exhibits a vibration type different from the vibration type,
The nodal position is moved. Since the nodal line portion is at the midpoint of the amplitude, when the movement of the CWM is stagnant, or when the rotation speed of the oscillator 18 is changed as described above, the nodal line position is moved and stagnated at the previous time. In addition, the amplitude of the CWM increases at a new time point, and the stagnation is eliminated by performing sieving and the stagnation of the CWM occurs at a new node line position. Therefore, when the rotational speed of the oscillator 18 is sequentially changed over time, the nodal line position moves on the sieve surface 12 following the above change, so that the resonance described above is eliminated while eliminating the occurrence of CWM stagnation. The sieving operation can be performed by optimizing the movement of the CWM under the frequency near the point. The sequential change of the rotational speed of the oscillator 18 with time is performed under the sequential circuit combined with the control circuit 82.

As described above, in this embodiment, the CWM flowing from the supply pipe 42 is agitated and mixed in the supply gutter 28 of the disperser 22 so that the CWM is in a dispersed state in which the concentration, particle size, etc. are uniform. Flows downward from the supply port 30, that is, the edge of the movable cover 32 in the form of a uniform film flow, and is uniformly diffused in the width direction of the screen surface 12 of the vibrating screen 10.
Wet sieving is performed by being supplied from the upper part of. Sieve surface 12
The oscillating force of the oscillator 18 is transmitted to give a vibration, and the CWM that has been evenly dispersed is sieved while descending the sieving surface 12 at a uniform moving speed while repeating jumping and sliding. It is separated into a coarse CWM which is a product on the screen and a fine CWM which is a product under the screen, and discharged.

The unbalanced weight of the oscillator 18 is rotated to generate a periodic motive force, which is transmitted to the sieving surface 12 via the transmitting element 16 and required in the plane of the sieving surface 12 in the normal direction. When vibrating under the amplitude and frequency, the sieve surface 1
The frequency of 2 is detected, and in order to vibrate the screen surface 12 at the frequency near the resonance point corresponding to the natural frequency of the screen surface 12, the rotation frequency of the oscillator 18 is controlled by the output signal of the frequency control means 82. Since it is controlled, the vibrating state of the screen surface 12 of the vibrating screen 10 is activated without being affected by the properties of the CWM, and the deterioration of the wet screening performance of the vibrating screen 10 is effectively prevented. The separation of coarse particles from the CWM can be ensured.

Next, when the sieving surface 12 is vibrated under a specific frequency, it exhibits a vibrating form having a specific vibration mode due to the movement under the structural parameters as described above, and a combination of vibration modes. As a result, a plurality of nodal lines are formed, and since the nodal line portion is set to the midpoint of the amplitude, the movement of the CWM is stagnated, or the oscillator 18 is generated by the output signal from the sequential circuit of the control circuit 82. When the number of revolutions of the No. 2 is sequentially changed over time, the nodal line position moves on the sieve surface 12 following the above change, so that the vibration near the resonance point is eliminated while eliminating the occurrence of the CWM stagnation. The sieving operation can be performed by optimizing the movement of the CWM based on the number.

[0025]

As described above, according to the present invention, during wet sieving of CWM exhibiting high viscosity, the frequency control means is used to perform frequency control with high control accuracy and stability, and vibration By vibrating the vibration state in the plane in the normal direction of the sieve surface of the sieve, it is possible to effectively prevent the deterioration of the wet sieving performance of the oscillating sieve and ensure the separation of coarse particles from the CWM. .

Further, by sequentially changing the rotational speed of the oscillator with time, the nodal line position on the screen surface moves on the screen surface in accordance with the above change, so that the stagnation of CWM occurs. It is possible to perform a sieving operation while optimizing the movement of the CWM under the frequency near the resonance point described above while eliminating the above-mentioned effects.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of a vibrating screen for coal / water slurry showing an embodiment of the present invention.

FIG. 2 is a circuit diagram of the sieve surface frequency control structure.

[Explanation of symbols]

 10 Vibration Screen 12 Screen Surface 16 Transmitter 18 Oscillator 70 Screen Frequency Control Structure

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masaaki Mikamo 1780 Kamitakano, Yachiyo-shi, Chiba Kawasaki Heavy Industries, Ltd. Yachiyo factory (72) Seiichiro Uchida 1780 Uetakano, Yachiyo-shi, Chiba Kawasaki Heavy Industries Ltd. Company Yachiyo factory

Claims (2)

[Claims] 1. A vibrating screen for wet sieving coal / water slurry, wherein the vibrating screen is connected to an oscillator via a transmitter on the screen surface, detects the frequency of the screen surface, and resonates the screen surface. Coal characterized by having a frequency control means for controlling the number of revolutions of the oscillator in order to vibrate at a frequency near the point
Sieve surface frequency control structure of vibrating sieve for water slurry. 2. The vibrating sieve for coal / water slurry according to claim 1, wherein the frequency control means includes a circuit for sequentially changing the rotational speed of the oscillator with time. Surface frequency control structure.