JPH0699103A - Abnormality judging device of densitometer in horizontal centrifugal concentrator - Google Patents

Abstract

PURPOSE:To judge the abnormality of a densitometer for conc. sludge in the sludge treatment in an centrifugal concentrator. CONSTITUTION:A concentration meter 17 for taken-out conc. sludge and a tachometer 18 are provided to a horizontal centrifugal concentrator A and the abnormality judging device B of the concentration meter 17 is also provided. The measured value of the concentration meter 17 and that of the tachometer 18 are inputted to a judging device B to judge the erroneous reading of the concentration meter 17 on the basis of the concn. of conc. sludge or the relation between the number of rotations of the outer cylinder of the concentrator and the canon. of conc. sludge and abnormality is displayed on a display device 30.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a horizontal centrifugal concentrator for determining an abnormality of a densitometer for detecting the concentration of concentrated sludge.

[0002]

2. Description of the Related Art Conventionally, in the sludge concentration treatment of a sewage treatment plant, Japanese Utility Model Publication No. 62-79556,
Horizontal centrifugal concentrators such as those described in U.S. Pat.

In this horizontal centrifugal concentrator, a screw conveyor that is rotated at a relative speed difference from the outer cylinder is provided in a cylindrical outer cylinder that is rotated at a high speed, and sludge supplied from one end is removed from the outside. Solid-liquid separation is carried out while transferring the annular space between the cylinder and the screw conveyor to the other end side, and the concentrated sludge is taken out from the outer peripheral part of the annular space and the separated water is taken out from the inner peripheral part. . In this type of machine, in order to keep the concentration of the concentrated sludge taken out constant, the rotation speed of the outer cylinder is controlled, and the concentration of the concentrated sludge is detected using a densitometer. .

[0004]

Torque detection type and ultrasonic type densitometers are generally used as the densitometers for detecting the above-mentioned thickened sludge. However, these densitometers have a problem of reliability. Is often misread, which makes control unstable. In other words, in the torque detection type, a high-concentration signal comes out when the sieve residue in the sludge is entangled. If this is done, the rotation speed of the outer cylinder will be reduced in response to that signal. As a result, the actual concentrated sludge concentration will be lower than the target value. Further, in the ultrasonic type, when bubbles are mixed in the concentrated sludge, a high-concentration signal is output, and in the same manner as above, the actual concentrated sludge concentration is controlled to be lower than the target value. .

The present invention has been made in view of the above points, and provides an apparatus capable of judging an abnormality in the detected value of a densitometer by a change in the value of the densitometer for detecting the concentration of concentrated sludge and the operating condition of the machine. It is intended to provide stable control of a horizontal centrifugal concentrator.

[0006]

Means for Solving the Problems The inventors of the present invention have conducted extensive studies in order to solve the above-mentioned problems, and as a result, in determining the abnormality of the detection value of the densitometer, the change with time of the detection value and the corresponding change It was found that the rotation speed of the outer cylinder is deeply related to the present invention, and the present invention has been completed. That is, the abnormality determination device for the densitometer of the present invention is that the sludge is supplied from one end side of the outer cylinder 1 containing the screw conveyor 4 and rotating at a high speed to perform solid-liquid separation,
Outside the horizontal centrifugal concentrator A and the densitometer 17 for measuring the concentration of the concentrated sludge to be taken out, the horizontal centrifugal concentrator A is designed to take out the concentrated sludge from the circumferential part on the other end side and the separated water from the central part. A device 18 for measuring the number of rotations of the cylinder 1 is installed, and the measured values of the concentration and the number of rotations are input, and the present concentration sludge concentration Cu ₂ and concentration sludge concentration Cu ₁ before a predetermined time X ₄ before the present Is larger than the set value X _{3 and} the difference between the current outer cylinder rotation speed Kb ₂ and the outer cylinder rotation speed Kb ₁ before the predetermined time X ₄ is smaller than the set value X _2. The current concentration of concentrated sludge Cu ₂
When the value becomes larger than the set value X _{1, a} judging device 30 is provided for emitting a signal indicating the abnormality of the densitometer 17.

[0007]

In the apparatus having the above-mentioned structure, the value of the densitometer 17 is input to the calculating unit 22 of the absolute concentration value determining unit 20 to the determining unit B, and the value of the tachometer 18 is input to the calculating unit 22. . Then, the input current concentration of concentrated sludge Cu ₂ and set value X
Comparison with ₁ (Cu ₂ > X ₁ ) The logical value signal d is output
Sent to.

Further, in the calculation unit 22, the difference between the current density Cu ₂ and the density Cu _{1 a} predetermined time X ₄ seconds before the current time and the set value X ₃ are set.
(Cu ₂ −Cu ₁ > X ₃ ) The logical value b, the difference between the current outer cylinder rotation speed Kb ₂ and the rotation speed Kb ₁ at a predetermined time X ₄ seconds before the present and the set value X ₂ The logical product of the comparison (Kb ₂ −Kb ₁ <X ₂ ) and the logical value a is calculated by the composite determination unit 24, and the logical value C is sent to the output determination unit 21, where the logical sum with the logical value d is obtained. It is calculated and the result is sent to the indicator 30 and the densitometer 17
Abnormalities are indicated.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is an overall schematic view of the device of the present invention, in which A is a horizontal centrifugal concentrator and B is a densitometer abnormality determiner.

As shown in FIG. 2, in the centrifugal concentrator A, an outer cylinder 1 is supported by bearings by hollow shafts 2 provided at both ends thereof, and is rotated at a high speed by a drive unit 3. A screw conveyor 4 having a screw on the outer periphery is housed in the outer cylinder 1, and a hollow rotary shaft 5 protruding from one end of the outer cylinder 1 is inserted into the hollow shafts 2 of the outer cylinder 1 to form a hollow on one side. The rotary shaft 5 protruding from the shaft 2 is connected to a drive device 6,
The screw conveyor 4 is adapted to rotate at a slight relative speed with respect to the outer cylinder 1. Then, one side of the rotary shaft 5 of the screw conveyor 4 is connected to the sludge input pipe 7 via a rotary joint, and the sludge passes through the rotary shaft 5 and forms an annular shape between the outer cylinder 1 and the screw conveyor 4. It is designed to be sent to one side of the space 8.

At the other end of the screw conveyor 4, a separated water take-out pipe 9 communicating with the annular space 8 is provided by being inserted into the hollow shaft 2 of the outer cylinder 1, and the tip end thereof is provided with a separated water discharge chamber 10. It is projected inside. Further, a concentrated sludge extraction pipe 12 having a tip protruding into the concentrated sludge discharge chamber 11 is inserted into the separated water extraction pipe 9 in a concentric manner, and an annular space 8 is provided at a closed proximal end portion thereof. An introduction pipe 13 opened to the outer peripheral portion of is connected.

At the opening of the concentrated sludge take-out pipe 12 projecting into the concentrated sludge discharge chamber 11, a concentrated sludge control valve 14 for adjusting the degree of opening to adjust the discharge amount is provided so as to be movable back and forth in the axial direction of the pipe. And the discharge chambers 10 and 11 each have an outflow pipe 1
5, 16 are provided, and a concentration meter 17 is provided in the outflow pipe 16 of the concentrated sludge. Further, the drive device 3 is provided with a tachometer 18 for the hollow shaft 2 that rotates the outer cylinder 1.

As shown in FIG. 3, the deciding device B includes an absolute sludge concentration absolute value deciding unit 20, an output deciding unit 21 and an arithmetic unit 22 which introduces the number of revolutions of the outer cylinder 1 and the concentrated sludge concentration. It has and.

The concentration sludge concentration Cu measured by the densitometer 17 is input to the absolute concentration determination unit 20, and the current concentration Cu ₂ is compared with a preset constant X ₁ (Cu ₂ > X ₁ ), a signal is sent to the output determination unit 23.

The concentration of the concentrated sludge is also input to the calculation unit 22, and the present concentration Cu ₂ and the preset constant X are set.
Difference between the density Cu ₁ (saved in the density memory 25) ₄ seconds ago Cu ₂ −Cu ₁ and the preset constant X
₃ is compared with the density change determination unit 26 (Cu ₂ −Cu ₁ )> X
₃ ), and the logical value b at that time is sent to the composite determination unit 24.

On the other hand, the number of revolutions Kb of the outer cylinder 1 measured by the tachometer 18 is input to the calculation unit 22, and the number of revolutions Kb ₂ at the present time and the number of revolutions before the preset constant X ₄ seconds. Kb difference ₁ (which is saved in the rotational speed memory 27) and (Kb ₂ -kb _1), and a constant X ₂ that is set in advance is compared with the rotation change decision unit 28 (Kb ₂ -kb _1)> Φ ₂ , the logical value a at that time is sent to the composite determination unit 24.

Then, the logical sum C of the above logical values a and b
Is sent to the output determination section 21, and the logical sum of the logical value C and the logical value d calculated previously is output.
That is, the output determination unit 21 determines that Cu ₂ > X ₁ or {(Kb ₂
-Kb ₁₎ <X _{2 and,, (Cu 2 -Cu 1)} > when X _3}, and outputs a signal indicating the abnormality of the densitometer 17, the signal is the marking unit 30 for example It will be sent and warned.

The above constants X _{1 to} X ₄ vary depending on the capacity and load of the centrifugal concentrator, but X ₁ = 5 to 7,
X ₂ = -90 to 110, X ₃ = -0.4 to 0.6, X ₄ = 23 to 25
It is better to set the range. In addition, for this determination, data on the concentration of concentrated sludge and the number of rotations of the outer cylinder for the past 23 to 25 times are required.

Therefore, when the abnormality of the densitometer 17 is indicated, the rotation speed of the outer cylinder is automatically maintained at a constant value, and then the operator returns the rotation speed of the outer cylinder to the original state to start the operation. continue. Since this operation is performed during operation, the operating rate does not decrease. When the number of revolutions is set by an inverter or the like, it is possible to use the set number of revolutions instead of measuring the number of revolutions with a tachometer.

[0020]

As described above, according to the present invention,
Enter the concentration of the concentrated sludge extracted from the centrifugal concentrator and the outer cylinder rotation speed of the centrifugal concentrator, and compare the current concentration with the set value, or the value at each time difference between the concentration and the revolution and the current time. From the relationship with the concentration, it is possible to judge the misreading of the densitometer caused by the entanglement of the sieve residue of the densitometer or the inclusion of air bubbles in the concentrated sludge, and it is possible to take action without stopping the centrifugal concentrator. As a result, the reliability of the densitometer is covered, and operation control can be performed without lowering the operating rate.

[Brief description of drawings]

FIG. 1 is an overall view showing an outline of a device of the present invention.

FIG. 2 is a vertical sectional view showing the centrifugal concentrator.

FIG. 3 is a block diagram of a determiner in the device of the present invention.

[Explanation of symbols]

 A Centrifugal concentrator B Judgment device 1 Outer cylinder 2 Hollow shaft 3 Drive device 4 Screw conveyor 5 Rotating shaft 7 Sludge supply pipe 8 Annular space 9 Separated water extraction pipe 12 Concentrated sludge extraction pipe 13 Introducing pipe 14 Concentrated sludge control valve 17 Concentration meter 18 Tachometer 20 Concentration absolute value judgment unit 21 Output judgment unit 22 Calculation unit 30 Indicator

Claims (1)

[Claims] A horizontal centrifugal concentrator that feeds sludge from one end of a high-speed rotating outer cylinder containing a screw conveyor for solid-liquid separation, and extracts concentrated sludge from the circumference of the other end and separated water from the center. At the same time, install a densitometer to measure the concentration of the extracted concentrated sludge and a device to measure the rotation speed of the outer cylinder of the horizontal centrifugal concentrator, and enter the measured values of the above-mentioned concentration and rotation speed to obtain the current concentration. The difference between the sludge concentration and the sludge concentration a predetermined time before the present is larger than the set value, and the difference between the current outer cylinder rotation speed and the outer cylinder rotation speed a predetermined time before the present is the set value. When it becomes smaller, or regardless of the above conditions, when the current concentration of concentrated sludge becomes higher than the set value, a judgment device that emits a signal indicating the abnormality of the densitometer is provided. The error determination of the concentration meter in the horizontal centrifugal concentrator Apparatus.