JPH10151370A - Method of controlling centrifugal dehydrator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make operation control easy by detecting turbidity of separated liquid and accordingly, automatically control the difference of rotational speed between a bowl and a screw conveyor. SOLUTION: When subjecting sludge to solid-liquid separation by a centrifugal dehydrator 1 containing a screw conveyor 4 rotated with relative speed difference between it and a bowl 3, separated liquid from the centrifugal dehydrator 1 is put in a separated liquid tank 15 provided with a turbid meter 16, and the turbidity of the separated liquid is measured there, and based on the result, the rotation of a hydraulic motor 9 for sending oil to a differential speed device 8 for controlling the rotation of the screw conveyor 4 is automatically controlled to always control the rotational speed difference between the bowl 3 and the screw conveyor 1 to an optimum state.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for controlling the operation of sludge such as sewage in accordance with the turbidity of a discharged separated liquid when centrifugally dewatering the sludge.

[0002]

2. Description of the Related Art Sludge generated in a water treatment process is generally
It is processed through each process such as concentration → (digestion) → dehydration → incineration. Of these, the filter press method is used for the dehydration treatment,
A belt press method and a centrifugal dehydration method are often used.

The centrifugal dewatering method includes a standard type and a high-efficiency type. The standard type has a constant differential speed, and the high-efficiency type detects a cake conveying torque to change the differential speed, thereby increasing the differential speed. It is characterized by being dehydrated and capable of following a certain degree of change in sludge properties.

[0004]

However, even in the above-mentioned high-efficiency centrifugal dehydration, when fluctuations in sludge properties exceed an allowable range or when the centrifugal dehydrator is started, a person checks the state of the separated liquid. However, since it is necessary to set operating conditions, it is necessary to constantly check the operating conditions, which requires skill in control and complicates the control operation.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems, and is intended to detect the turbidity of a separated liquid and automatically control the rotational speed difference between a bowl and a screw conveyor accordingly. It is intended to facilitate operation management, improve dewatering efficiency, and achieve stable solid-liquid separation.

[0006]

The configuration of the present invention for achieving the above object will be described with reference to the drawings corresponding to the embodiments.
The turbidity of the separated liquid discharged from the centrifugal dehydrator 1 is measured when the solid-liquid separation of the sludge is performed by the centrifugal dehydrator 1 containing the screw conveyor 4 rotated at a relative speed difference from the ball 3. And based on that measurement,
It is characterized in that the rotation of a hydraulic motor 9 that feeds oil to a speed difference device 8 that gives a relative speed difference to the screw conveyor 4 is automatically controlled.

[0007]

Embodiments of the present invention will be described below with reference to the drawings. In the figure, reference numeral 1 denotes a horizontal centrifugal dehydrator. As is conventionally known, a bowl 3 and a screw conveyor 4 having a screw 6 on the outer periphery of a hollow rotary shaft 5 are housed in a casing 2 as conventionally known. Is rotated at a high speed by a main motor 7 provided on the tip side of the casing 2, and the screw conveyor 4 is slightly rotated by the speed difference device 8 provided on the tip side of the casing 2. (Differential speed). The speed difference device 8 is controlled by a hydraulic motor 9 that sends oil thereto.

The sludge is stored in a sludge tank 10 and supplied to the centrifugal dehydrator 1 by a sludge supply pump 11. At this time, the coagulant dissolved in the chemical dissolution tank 12 is supplied by the chemical supply pump 13, and the sludge is coagulated and easily separated. The dewatered sludge is discharged out of the centrifugal dewatering machine 1 from the front end thereof, and is carried out of the system by the cake transport facility 14. On the other hand, the separated liquid is taken out from the base end of the centrifugal dehydrator 1 and once stored in the separated liquid tank 15 and then discharged out of the system.

In the operation of the centrifugal dehydrator, when the speed difference between the bowl 3 and the screw conveyor 4 is reduced, sludge is accumulated in the dehydrator, and a dewatered cake having a low water content is discharged due to the consolidation effect. However, if the differential speed is too small, the separation property deteriorates, and solids escape to the separation liquid side, so that the separation liquid becomes turbid. In order to avoid this, it is necessary to increase the oil supply amount of the hydraulic motor 9 to increase the speed difference. In addition, when the differential speed is increased, the turbidity of the separated liquid decreases because the sludge passes through the dehydrator faster, but the water content of the dehydrated cake increases. In such a case, it is necessary to reduce the difference in speed by reducing the oil supply amount of the hydraulic motor 9.

In the present invention, the turbidity meter is
Set 16 and measure the turbidity of the separated solution. Then, based on the measured value of the turbidity, the hydraulic motor 9 for feeding oil to the speed difference device 8 is automatically controlled. That is, the turbidity meter 16
The turbidity specified value can be set in the hydraulic motor 9 when the measured turbidity is higher than the specified value.
When the measured turbidity is lower than the specified value, the rotational speed of the hydraulic motor 9 is increased. Reduced speed difference device 8
The amount of music to be transmitted is reduced, and the speed difference is reduced.

[0011]

As described above, according to the present invention,
By detecting the turbidity of the separated liquid discharged from the centrifugal dehydrator and controlling the hydraulic motor that feeds the oil to the speed difference device based on the measurement result, the water content of the dewatered cake can be kept low, Separation liquid turbidity can be kept low, and the return water load to water treatment can be reduced. In addition, since the operating conditions relating to the speed difference between the bowl and the screw conveyor can be automatically changed and set, operation management can be easily performed without skill, and the processing efficiency of the centrifugal dehydrator can be improved.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing one embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Centrifugal dehydrator 2 Casing 3 Bowl 4 Screw conveyor 7 Main motor 8 Differential speed device 9 Hydraulic motor 10 Sludge tank 11 Sludge supply pump 12 Chemical dissolution tank 13 Chemical supply pump 15 Separation liquid tank 16 Turbidity meter

Claims (1)

[Claims] In a high-speed rotating ball, a centrifugal dehydrator containing a screw conveyor rotated with a relative speed difference from this ball, when performing solid-liquid separation of sludge, the turbidity of the separated liquid discharged from the centrifugal dehydrator A method for controlling a centrifugal dehydrator, comprising measuring and automatically controlling the rotation of a hydraulic motor that feeds oil to a speed difference device that gives a relative speed difference to a screw conveyor based on the measured value.