JP2785856B2 - Apparatus and method for measuring turbidity of separated liquid in centrifugal dehydrator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a centrifugal dehydrator for separating sludge into solids and liquids and separating the sludge into a separated liquid and a dewatered cake, and relates to an apparatus for continuously monitoring the turbidity of the separated liquid.

[0002]

2. Description of the Related Art Since the separated liquid of a centrifuge contains suspended solids (SS), it is necessary to measure the concentration of SS, that is, turbidity, for post-treatment.

[0003] In a normal optical or ultrasonic turbidity meter, if bubbles are present in the measurement liquid, accurate measurement cannot be performed due to scattering of light or sound waves. Therefore, a certain amount of a measurement sample of the separated solution was collected and left to stand for measurement of turbidity so as not to be affected by bubbles in the separated solution of the centrifugal dehydrator. Conventionally, there has been no apparatus for continuously measuring the turbidity of a separated liquid from a centrifugal dehydrator.

[0004]

SUMMARY OF THE INVENTION In order to continuously monitor the operation status of the centrifugal dehydrator and to meet the demand for automatic control, it has been necessary to continuously measure the turbidity of the separated liquid of the centrifugal dehydrator. .

[0005] However, since the separated liquid contains a flocculant, it has a property of easily foaming. Therefore, there is a problem that the turbidity of the separated liquid must be continuously measured without being affected by bubbles in the separated liquid of the centrifugal dehydrator.

An object of the present invention is to solve the above-mentioned problems and to provide an apparatus for measuring the turbidity of a separated liquid of a centrifugal dehydrator, which makes it possible to monitor the operation status of the centrifugal dehydrator and automatically control the same.

[0007]

In order to achieve the above object, a turbidity measuring apparatus for a centrifugal dehydrator according to the present invention is configured to remove suspended solids adhering to bubbles in a separated liquid of a centrifugal dehydrator from the foam. A mixing tank for stirring and mixing the separated liquid in order to separate and uniformly distribute the separated liquid in the separated liquid; a foam separation tank for defoaming the mixed and separated bubbles in the separated liquid by gas-liquid separation; And a device for measuring the turbidity of the degassed separated liquid. Further, the turbidity measuring method of the present invention is a method of separating a suspended solid adhering to foam in a separated liquid of a centrifugal dehydrator from the foam and stirring the separated liquid to uniformly distribute the separated solid in the separated liquid. After that, the foam in the separated liquid is defoamed by gas-liquid separation, and the turbidity of the defoamed separated liquid is continuously measured.

[0008]

The separated liquid from the centrifugal separator flows into the mixing tank and is stirred and mixed by a mixer or the like. By this stirring step, not only the turbidity and the distribution of bubbles in the separated solution are made uniform, but also the suspended solids attached to the bubbles are separated from the bubbles and uniformly distributed in the separated solution. The stirring may be stirring in a pipe depending on the turbidity of the separated liquid. Then, the separated and mixed liquid is transferred to a foam separation tank. The foam in the separated liquid transferred to the foam separation tank is discharged from the upper outlet of the foam separation tank by the rise of the foam from the liquid phase to the gas phase, and the defoamed liquid is separated at the bottom of the foam separation tank.

When the defoamed separated liquid discharged from the outlet of the foam separation tank via a piping system connected to the bottom of the foam separation tank is measured by a turbidity measuring device attached to the piping system, the liquid is affected by the bubbles. Without this, the turbidity of the separated liquid can be continuously measured.

[0010]

An embodiment will be described with reference to FIG.

FIG. 1 clearly shows the system relationship of the configuration of the turbidity measuring device. The system shown in FIG. 1 is composed of a mixing tank 1, a foam separation tank 3, and pipes 5, 6, for transferring separated liquid and foam. 8, 9, 1
1 and 12.

The capacity of the mixing tank 1 is 2 l, and the rotation speed of the mixer 2 is 5 to 200 rpm. The rotation speed of the mixer 2 is changed according to the concentration of the separated liquid.

The volume of the foam separation tank 3 is 2 liters and the size is 110
mmΦ × 250 mmH. The turbidimeter is an optical densitometer S
Using SD-20 type (electrochemical meter), it was arranged between the pipe 8 and the pipe 9.

The centrifugal dehydrator separation liquid is supplied to the mixing tank 1 at a flow rate of 15%.
Charged at ２０20 l / min and stirred. By this stirring, the lump of SS and the like were dispersed, the turbidity became homogenous, and the contaminants adhering to the foam were removed and transferred into the liquid.

The stirred separated liquid was transferred to the foam separation tank 3. Then, the bubbles rose from the liquid phase to the gas phase, only the bubbles overflowed from the upper outlet 10, and the defoamed liquid flowed out from the lower outlet 7. As a result, it was confirmed that bubbles could be almost completely separated.

While the separated liquid flows from the outlet 10 in the foam separation tank 3 to the outlet 7 as one of the features of the present invention, the rise of the bubbles is utilized, and only the bubbles are caused to flow out of the outlet 10 by overflow. 7, it was confirmed that a defoamed liquid was obtained.
The upper 1/3 of the foam separation tank 3 was occupied by the foam 14, and the lower 2/3 by the separated liquid 13. The defoamed liquid flowing out from the outlet 7 is measured by an optical densitometer SSD-20 type (electrochemical meter), mixed with the foam overflowing from the outlet 10 through the foam separation tank 3, and discharged through the pipe 12. Was.

Table 1 shows the results of the density measurement.

[0018]

[Table 1]

As shown in Table 1, when the mixing tank and the foam separation tank were combined, a measured value consistent with the JIS test method was obtained. On the other hand, when the measurement is performed without separating the foam, the turbidity is detected larger than the JIS test method,
It can be seen that even when only the foam separation tank is used, the variation from the measured value is large.

[0020]

Since the present invention is configured as described above, it has the following effects.

Even if bubbles are contained in the separated liquid of the centrifugal dehydrator, the turbidity of the separated liquid can be continuously measured without being affected by the bubbles. Therefore, by continuously measuring the turbidity of the separated liquid of the centrifugal dehydrator, it becomes possible to monitor and automatically control the operation state of the centrifugal dehydrator based on the measurement of the separated liquid. In addition, the number of revolutions of the mixer in the mixing tank can be controlled according to the turbidity, and the processing flow rate of the centrifugal dehydrator can be optimized. In addition, according to the present invention, it can be used for measuring the turbidity of not only the separated liquid of the centrifugal dehydrator but also various liquids containing bubbles.

[Brief description of the drawings]

FIG. 1 is a system diagram of a separation turbidity measuring device of a centrifugal dehydrator.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Mixing tank 2 Mixer 3 Foam separation tank 4 Turbidity measuring device 5 Centrifugal separation liquid inflow pipe 6 Transfer pipe 7 Separation tank defoaming liquid outlet 8, 9 Defoaming liquid transfer pipe 10 Separation tank foam outlet 11 Foam discharge Piping 12 Outflow piping 13 Defoaming liquid 14 Foam

Claims (2)

(57) [Claims] A mixing tank for stirring and mixing the separated liquid to separate suspended solids attached to bubbles in the separated liquid of the centrifugal dehydrator from the bubbles and to distribute the separated solids homogeneously in the separated liquid; A centrifugal separation tank configured to defoam the bubbles in the stirred and separated liquid by gas-liquid separation based on a difference in specific gravity, and a device for measuring the turbidity of the separated liquid from which the bubbles have been defoamed; Turbidity measurement device for dehydrator separation liquid. 2. The centrifugal dewatering machine separates suspended solids adhering to bubbles in the separated liquid from the foam and stirs the separated liquid to uniformly distribute the separated solids in the separated liquid. A method for measuring turbidity of a separated liquid in a centrifugal dehydrator, comprising defoaming the foam therein by gas-liquid separation based on a specific gravity difference, and continuously measuring the turbidity of the defoamed separated liquid.