JP2505967B2 - Liquid supply method of centrifuge - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid supply method for controlling the supply of a stock solution into a basket of a centrifuge.

[0002]

2. Description of the Related Art As is well known, a centrifuge is an apparatus for separating a stock solution supplied into a basket rotating at a high speed into a solid matter (cake) and a liquid content by utilizing centrifugal force.
In the centrifuge, a liquid supply pipe having a liquid supply port oriented toward the inner peripheral side of the basket is inserted into the basket, and the stock solution is supplied from the liquid supply pipe to the inner peripheral side of the basket.

FIG. 4 shows an example of a conventional vertical centrifuge. In FIG. 4, reference numeral 1 denotes a cylindrical casing supported by a base 2 via a shock absorber 3. A bearing device 5 is attached to a cover 4 that closes an opening at the upper end of the casing 1, and a rotating shaft 6 is supported by the bearing device 5. The cover 4 is reinforced by a reinforcing plate 4a. The rotating shaft 6 is provided so as to extend in the vertical direction, and a basket 7 is attached to the rotating shaft 6.

The basket 7 has a peripheral wall portion 7a, an annular end wall 7b provided so as to project radially inward from the upper end of the peripheral wall portion, and a bottom wall portion 7c. Has a large number of through holes 7d. A boss portion 7e is provided at the center of the bottom wall portion 7c, and the boss portion 7e is attached to the rotary shaft 6
Around the boss portion 7e, a solid matter discharge port 7g partitioned by a large number of radially arranged ribs 7f is formed. A discharge port 1b is formed in the bottom 1a of the casing 1 so as to match the solid substance discharge port 7g. At the lower part of the peripheral wall of the casing 1, the through hole 7d of the basket 7 is formed.
A discharge port 1c for discharging the liquid component separated through is provided. A filter (not shown) is attached to the inner circumference of the basket 7, and the liquid component is discharged through the filter and the through hole 7d.

A hydraulic motor 8 for rotationally driving the rotary shaft 6 is attached to the upper end of the bearing device 5, and the basket 7 is rotationally driven by the hydraulic motor. An electric motor driven by an inverter or the like may be used instead of the hydraulic motor.

[0006] In order to supply the undiluted solution (slurry) into the basket 7, a liquid supply pipe 9 which is attached through the cover 4 of the casing is inserted into the basket 7. The liquid supply pipe 9 has a liquid supply port 9A at its lower end, and the lower end of the liquid supply pipe is bent at a right angle so that the liquid supply port 9A is directed to the inner circumference of the basket 7. Liquid supply port 9A
The opening is formed in an oval shape so as to have a vertically long shape, as shown in FIGS. 5 (A) and 5 (B), for example.

A scraping device 10 is also inserted in the basket 7. This scraping device 10 is supported by a bearing device 11 fixed to the upper surface of a cover 4 of a casing and is inserted into a basket 7.
Fixed to the cover 4; a scraping blade 13 attached to the No. 2; a guide plate 14 attached to the lower end of the scraping blade 13 to guide the solid matter scraped by the scraping blade 13 to the discharge port 7g side; And a drive mechanism 17 for rotating the rotating shaft 12 by means of a hydraulic cylinder 16 attached to the support plate 15.

[0008]

In the centrifugal separator described above, the supply pipe 9 is provided in the basket 7 rotating at high speed.
When the stock solution is supplied from the above, the stock solution is separated into a solid matter and a liquid component by centrifugal force. The liquid component is discharged into the casing 1 through the through holes 7d of the basket 7, and a solid layer S is formed on the inner periphery of the basket 7. In a vertical centrifuge with the rotation axis of the basket oriented in the vertical direction, solids tend to move downward under the influence of gravity, so the basket 7
The solid material layer S formed on the inner circumference of the
The bottom part will be thicker.

As described above, when the thickness of the solid layer S formed on the inner circumference of the basket becomes uneven and the inner surface of the solid layer has large irregularities, the washing liquid is solidified in the solid washing step performed later. When the cleaning liquid is supplied toward the layer S, the cleaning liquid flows into the thin portion (concave portion) of the solid layer S, and the cleaning of the solid substance cannot be performed uniformly. In order to uniformly wash the solid matter, it is necessary to generate a solid matter layer S having a substantially uniform thickness and less unevenness on the inner surface.

Therefore, various measures have been proposed for obtaining a solid material layer having a substantially uniform thickness on the inner circumference of the basket. For example, as shown in FIG. 6, the liquid supply pipe 9 is provided with a plurality of liquid supply ports 9A, 9B, and 9C at intervals in the vertical direction to aim at making the thickness of the solid layer S uniform. However, in this case, the amount of undiluted liquid flowing out from each liquid supply port is not uniform, and the amount of outflow from the liquid supply port located below is larger than the amount of outflow from the liquid supply port located above. Therefore, the thickness of the portion below the solid layer S tends to increase. Further, the thickness of the solid layer S becomes thicker in the portion near the liquid supply port, and becomes thinner as the distance from the liquid supply port increases. Therefore, as seen in FIG. 5, it is inevitable that the thickness of the solid layer S is non-uniform, and that large irregularities are formed on the inner surface thereof.

Further, a plurality of liquid supply pipes having different vertical positions of the liquid supply ports are inserted into the basket to devise an equal amount of the stock solution to flow out from the liquid supply ports of the respective liquid supply pipes. However, even in this case, the thickness of the solid layer becomes thicker at the position close to the liquid supply port, and becomes thinner at the part away from the liquid supply port. It is inevitable that large unevenness will occur.

An object of the present invention is to propose a liquid supply method for a centrifuge, which is capable of forming a solid material layer having less unevenness on the inner surface.

[0013]

SUMMARY OF THE INVENTION According to the present invention, a liquid supply pipe formed so that a liquid supply port is directed to an inner peripheral side of the basket is inserted into a basket which rotates around a rotation shaft extending in a vertical direction. However, the present invention relates to a liquid supply method of a centrifuge for separating the undiluted liquid supplied from the liquid supply pipe to the inner peripheral side of the basket into a solid matter and a liquid component.

In the present invention, the liquid supply port is arranged so as to be able to move up and down in the axial direction of the basket, and the undiluted solution is concentratedly supplied to the portion where the solid layer formed on the inner circumference of the basket is thin. The stock solution is supplied while controlling the vertical position of the liquid supply port so as to correct the thickness of each part of the solid material layer.

In order to perform the above control, for example, when a predetermined amount of stock solution is supplied to the basket, the solution supply is stopped to expose the inner surface of the solid layer, and the thickness of each part of the solid layer is detected. Then, the position of the liquid supply port may be controlled so that the stock solution is mainly supplied to the thin portion.

Further, a plurality of liquid supply positions are set at intervals in the axial direction of the basket, and the thickness of the solid layer formed on the inner circumference of the basket is detected at each set liquid supply position,
When there is a difference in the thickness of the solid layer detected at each of the plurality of liquid supply positions, the liquid supply port is moved to the liquid supply position where the detected thickness of the solid layer is the smallest to supply the undiluted solution. You may do it .

In the method of the present invention, it is possible to control the position of the liquid supply port according to the thickness of the solid layer and at the same time control the amount of the stock solution flowing out from the liquid supply port at each position.

[0018]

As described above, the liquid supply port of the liquid supply pipe can be moved up and down, and the undiluted solution is supplied mainly to the thin portion of the solid layer formed on the inner circumference of the basket to solidify the solid solution. When the undiluted liquid is supplied while controlling the vertical position of the liquid supply port so as to correct the thickness of each part of the solid layer, it is possible to reduce the unevenness of the inner surface of the solid layer formed on the inner circumference of the basket. Therefore, the solid matter can be uniformly washed in the washing step, and the quality of the obtained solid matter can be improved.

In controlling the position of the liquid supply port, the liquid is supplied at each of a plurality of liquid supply positions set at intervals in the vertical direction, and the thickness of the solid layer is adjusted at each liquid supply position. If a method is adopted in which the liquid supply port is moved to the liquid supply position where the detected solid layer thickness is the thinnest, a sensor for detecting the solid layer thickness is arranged at each liquid supply position. Since this is sufficient, the present invention can be implemented without using a complicated detection device that continuously detects the thickness of each part of the solid layer .

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an example of the configuration of a centrifuge for carrying out the method of the present invention. In FIG. 1, parts equivalent to those of the conventional centrifuge shown in FIG. The symbol is attached. The liquid supply pipe 9 used in the present embodiment is similar to that shown in FIG. 5, in which the lower end of a pipe extending in the axial direction of the basket is bent at a right angle to the inner peripheral side of the basket, and the lower end is provided with the inner peripheral of the basket. Pointing to the side 1
It has one liquid supply port 9A. The shape of the liquid supply port 9A is not limited to that shown in FIG. 5, and may be formed into another shape such as a circle.

The liquid supply pipe 9 is vertically movably supported by a thrust bearing provided in a portion penetrating the cover 4 of the casing, and the liquid supply port 9A at the lower end thereof is set at a position near the upper end of the basket. It is provided so as to be able to move up and down between an upper limit position (a position indicated by a chain line in the figure) and a lower limit position (a position indicated by a solid line in the figure) set at a position near the bottom of the basket.

A hydraulic or air cylinder 20 is mounted on the upper surface of the cover 4 of the casing with the axis of the cylinder 20 oriented vertically, and the piston rod 20A of the cylinder 20 is attached.
Is inserted into the basket through the cover 4.
The piston rod 20A is arranged parallel to the liquid supply pipe 9, and the lower end of the liquid supply pipe 9 and the lower end of the piston rod 20A are connected by a connecting plate 21. Therefore, when the cylinder 20 is driven, the liquid supply pipe 9 moves up and down together with the piston rod 20A, and the liquid supply port 9A moves up and down.

A frame 22 extending parallel to the liquid supply pipe 9 is also mounted on the cover 4, and a plurality of frames (in the example shown in the figure, 5) are spaced apart from each other in the vertical direction of the frame 22.
Limit switches 23a to 23e are attached. An operator 24 for operating a limit switch is attached to the upper end of the liquid supply pipe 9, and the operator comes into contact with the operating portion of each limit switch to operate each limit switch. Limit switches 23a-2
The positions provided with 3e correspond to the five liquid supply positions set in the basket, and the limit switches 23a and 23e correspond to the upper limit position and the lower limit position, respectively. Limit switches 23a-23e
The signal obtained by is given to a cylinder driving device (not shown). The drive device is a limit switch 23.
Each of the liquid supply positions is detected by a to 23e, and the cylinder 20 is driven so as to move the liquid supply port 9A to the designated liquid supply position.

A sensor support tube 25 extending in the axial direction is inserted into the basket 7, and thickness sensors 26a to 26e are attached to the support tube. Each of the thickness sensors 26a to 26e has a limit switch 23a.
23e are arranged at the liquid supply positions in the basket corresponding to 23e, and the thickness of the solid layer is detected by measuring the distance to the inner surface of the solid layer S at each liquid supply position.
As a sensor for detecting the thickness of the solid layer S, the distance from the time until the ultrasonic wave radiated toward the object to be measured is reflected and returned on the surface of the object to be measured to the surface of the object to be measured is detected. Ultrasonic type distance sensor, a capacitance type distance sensor utilizing the fact that the capacitance between a predetermined electrode and the object to be measured changes depending on the distance between the electrode and the object to be measured, or A nozzle that ejects air toward the measurement object is provided, and when the gap between the nozzle and the measurement object changes, the amount of air that flows out from the nozzle changes It is possible to use a pneumatic micrometer for measuring the distance between them, an optical sensor such as an image sensor or the like for detecting surface irregularities using an optical detection element, or the like.

The output line 27 led from the thickness sensors 26a to 26e is led to the outside through the inside of the support tube 25 and supplied to a control device (not shown). The upper end of the liquid supply pipe 9 is connected to a pipe connected to a stock solution supply tank via a bellows 28 and a flow rate adjusting valve 29. Other configurations are the same as those shown in FIG.

In this embodiment, the operation panel 30 is attached to the upper side surface of the casing 1, and the cylinder 20 is driven by manually operating the button provided on the operation panel 30 to move the liquid supply pipe 9 up and down. It can be moved.

In the liquid supply method of the present invention, the thickness of the solid layer S formed on the inner circumference of the basket by the sensors 26a to 26e at a plurality of liquid supply positions set at intervals in the axial direction of the basket 7. When there is a difference in the thickness of the solid layer detected at each of the plurality of liquid supply positions, the liquid supply port 9A is moved to the liquid supply position where the detected thickness of the solid layer is the smallest. Supply undiluted solution. The liquid supply port 9A can be controlled by a PC using a microcomputer or a sequencer.

Next, one embodiment of the liquid supply method of the present invention using the centrifuge of FIG. 1 will be described with reference to the flow chart of FIG. When processing the undiluted solution, first, the basket 7 is activated and rotated at a high speed to start moving up and down the liquid supply port 9A. When raising and lowering the liquid supply port 9A, the limit switch 23 is used to switch the upper limit position and the lower limit position of the liquid supply port 9A.
a and 23e, and by reversing the driving direction of the cylinder every time when the limit position of the liquid supply port is detected by each limit switch, the liquid supply pipe 9 is moved up and down to reciprocate, and the liquid supply port 9A is opened. Reciprocating displacement is performed between the upper limit position and the lower limit position.

After the liquid supply port 9A is started to move up and down, liquid supply is started and a timer for measuring the liquid supply time is started.
When the time T measured by the timer reaches a preset liquid supply time To, the liquid supply is stopped and at the same time, a timer for measuring the liquid removal time is started to perform liquid removal. When the measured time T of the timer reaches the preset liquid removal time T1, the thickness dx of each part of the solid layer S is measured by the sensors 26a to 26c.
26e to detect. The deliquoring time T1 is set long enough to expose the inner surface of the solid layer S. Next, the maximum value of the difference in thickness calculated by calculating the difference between the thicknesses of the respective portions of the solid layer detected by the sensors 26a to 26e (the absolute value of the difference between the maximum value and the minimum value of the detected thickness) is calculated. ) Is the maximum deviation Δd, and this maximum deviation Δd is compared with the allowable value Δdo. As a result, when the maximum deviation is larger than the allowable value, the cylinder 20 is driven to move the liquid supply port 9A,
Among the limit switches 26a to 26e, the liquid supply port 9A is stopped when the limit switch corresponding to the liquid supply position where the minimum value of the solid layer thickness dx is detected operates. The stop position of the liquid supply port at this time is a liquid supply position corresponding to a portion where the thickness of the solid layer is thinnest among a plurality of liquid supply positions set at intervals in the axial direction of the basket. The liquid supply is started at this liquid supply position and the liquid supply time measuring timer is started. When the measured time T of the timer becomes equal to the set value T2, the liquid supply is stopped and the timer for measuring the liquid removal time is started. When the liquid removal time T1 has elapsed, the thickness dx of each part of the solid layer is detected again, and the maximum deviation .DELTA.d is calculated. As a result, the maximum deviation Δd is the allowable value Δ
When it is larger than do, the liquid supply port 9A is moved to the liquid supply position where the minimum value of the solid layer thickness dx is detected to start the liquid supply, and at the same time, the timer is started, and the measured time of the timer. When T becomes equal to the set value T2, the liquid supply is stopped and the timer for measuring the liquid removal time is started.
As a result of repeating these steps, when the maximum deviation .DELTA.d becomes equal to or smaller than the allowable value .DELTA.do, the average value dxm of the solid layer thickness dx is calculated, and this average value dxm is compared with the set value dxmo. As a result, when the average value dxm does not reach the set value (when a predetermined amount of solid material layer is not formed), the liquid supply port is started to move up and down, and liquid supply is performed again. repeat. When the average value dxm of the thickness of the solid layer has reached the set value, the liquid supply process is terminated, the final liquid removal process is performed, and then the cleaning process is performed.

When the liquid is supplied by the above-mentioned method, the thickness of each part of the solid layer can be made substantially uniform and the unevenness of the inner surface can be reduced, so that the solid is washed in the subsequent washing step. It can be carried out uniformly and the quality of the obtained solid matter can be improved.

In the embodiment shown in FIG. 1, the piston rod 20A of the cylinder 20 is inserted into the basket so that the piston rod 20A and the liquid supply pipe 9 are connected in the basket. The piston rod 20A and the liquid supply pipe 9 may be connected above the cover 4 by mounting the piston rod 20A in the opposite direction.

The means for driving the liquid supply pipe is not limited to the cylinder, and, for example, as shown in FIG.
A screw rod 32 may be screwed into a screw hole provided in a plate 31 fixed to the liquid supply pipe 9, and the liquid supply pipe 9 may be vertically moved by rotationally driving the screw rod 32 by an electric motor 33. . In this case, the stop position of the liquid supply port 9A can be controlled by controlling the electric motor 33.

In the above embodiment, five liquid supply positions are set in the basket 7, but the number of liquid supply positions set in the present invention is arbitrary. Generally, the greater the number of liquid supply positions, the smaller the variation in the thickness of the solid layer. When the particles of the solid matter to be generated are dense, it is difficult for the washing liquid to escape in the washing step. Therefore, it is desirable to minimize the deviation in the thickness of each part of the solid matter layer. It is preferable to set as many as possible. On the other hand, when the particles of the solid material are coarse, the cleaning liquid is likely to escape, and even if the inner surface of the solid material layer has some irregularities, the cleaning is performed without any trouble, and therefore the number of liquid supply positions may be small. .

In the above embodiment, only the upper and lower positions of the liquid supply port 9A are controlled according to the thickness of the solid layer, but the amount of the stock solution flowing out from the liquid supply port 9A is controlled at each position. You can also do it. For example, when the deviation of the thickness of the solid layer is large, a large amount of the stock solution is supplied, and when the deviation is small, the amount of the stock solution to be supplied is reduced so that the deviation of the thickness of the solid layer is reduced. The flow rate of the stock solution may be controlled. The control of the flow rate of the undiluted solution flowing out from the liquid supply port at each position may be performed by adjusting the opening degree of the flow rate adjusting valve (not shown) while keeping the liquid supply time T2 constant. Alternatively, it may be performed by changing the liquid supply time T2.

In the above embodiment, a plurality of liquid supply positions are set in the basket and the position of the liquid supply port 9A is controlled stepwise. However, the position of the liquid supply pipe is continuously detected. By providing a position sensor for obtaining the liquid supply pipe and controlling the drive source of the liquid supply pipe so that the position of the liquid supply pipe detected by the position sensor coincides with the target position, the position of the liquid supply port 9A is continuously changed. It may be controlled. Figure 2
When the liquid supply pipe 9 is configured to be moved up and down by the electric motor 33 via the screw rod 32 as shown in, the rotary encoder 34 for detecting the rotation of the electric motor 33 is attached, and the output of the encoder 32 is changed. By detecting the position of the liquid supply port 9A and controlling the rotation of the electric motor 33 so that the deviation between the detected position and the target position (the position where the solid layer is thin) is zero, the liquid supply port 9A The position of can be controlled continuously. In this way, when continuously controlling the position of the liquid supply port, it is necessary to continuously detect the thickness of each portion of the solid material layer, so that the support rod that is driven in the vertical direction is set in the basket. And the thickness sensor is attached to the support rod, and the support rod is moved up and down to detect and store the thickness of each portion of the solid layer .

[0036] In the above example, the bottom of the basket is fixed.
Taking a centrifuge of the type having a shape discharge port as an example
Close the bottom of the basket and
Scrape off solids to the bottom of the basket with scraping device 10
Vacuum the solids that collect at the bottom of the basket.
Type that discharges to the outside through discharge means such as used suction pipe
Of course, the present invention can be applied to the centrifugal separator of
You.

In the embodiment shown in FIG. 1, a limit switch is used as a position sensor for detecting the position of the liquid supply pipe, but a sensor for detecting the position of the liquid supply pipe without contact may be used.

[0038]

As evident from the foregoing description, according to the present invention, as capable of lifting the liquid supply port of the liquid supply pipe, to detect the thickness of each portion of the solid-form material layer, it detected a small thickness portion since then supplied intensively stock solution, Ru can control the position of the liquid supply ports in line with the actual change in thickness of the solid layer formed on the inner periphery of the basket. Therefore , regardless of the type of stock solution, it is possible to properly control the liquid supply position and obtain a solid material layer with less unevenness on the inner surface, which can be used in the cleaning process.
The solid matter can be uniformly washed.

[Brief description of drawings]

FIG. 1 is a sectional view showing a configuration example of a centrifuge for carrying out the method of the present invention.

FIG. 2 is a sectional view showing a main part of a modified example of a centrifuge used for carrying out the method of the present invention.

FIG. 3 is a flowchart showing an algorithm for position control of a liquid supply port in the embodiment of the present invention.

FIG. 4 is a cross-sectional view showing a configuration of a centrifugal separator that performs liquid supply by a conventional liquid supply method.

5A and 5B are a front view and a side view showing a main part of a liquid supply pipe.

FIG. 6 is a sectional view showing a centrifuge adopting another conventional liquid supply method.

[Explanation of symbols]

 1 Casing 7 Basket 8 Hydraulic Motor 9 Liquid Supply Pipe 9A Liquid Supply Port 10 Scraping Device 20 Cylinder 23a-23e Limit Switch 26a-26e Thickness Sensor

Claims (2)

(57) [Claims] 1. A liquid supply pipe formed so that a liquid supply port is directed to an inner peripheral side of the basket is inserted into a basket which rotates around a rotation shaft extending in a vertical direction, and the basket is supplied from the liquid supply pipe. Is a method of feeding a centrifuge that separates the undiluted solution supplied to the inner peripheral side into a solid matter and a liquid content, wherein the solution feeding port is arranged to be movable up and down in the axial direction of the basket. When a predetermined amount of the undiluted solution has been supplied, the liquid feeding is temporarily stopped to expose the inner surface of the solid layer, the thickness of each part of the solid layer is detected, and the undiluted solution is focused on the thin portion. A liquid supply method for a centrifuge, characterized in that the thickness of each part of the solid material layer is corrected by controlling the position of the liquid supply port in this manner to obtain a solid material layer with less unevenness on the inner surface. 2. A liquid supply pipe formed so that a liquid supply port is directed to an inner peripheral side of the basket is inserted into a basket which rotates around a rotation shaft extending in a vertical direction, and the basket is supplied from the liquid supply pipe. A method of feeding a centrifuge that separates the undiluted solution supplied to the inner peripheral side into a solid matter and a liquid matter, wherein the solution feeding port is arranged to be movable up and down in the axial direction of the basket, A plurality of liquid supply positions are set at intervals in the axial direction, and the thickness of the solid layer formed on the inner circumference of the basket is detected at each of the set liquid supply positions. When there is a predetermined difference in the thickness of each solid layer detected, the liquid supply port is moved to the liquid supply position where the detected thickness of the solid layer is thinnest to supply the undiluted solution. And the method of supplying liquid to the centrifuge.