JPH05285500A - Method and apparatus for controlling dehydration of slurry - Google Patents

Abstract

PURPOSE:To control the addition of a polymeric flocculant so that the addition amount of the flocculant to a slurry becomes optimum in order to minimize the water content of a dehydrated cake when the slurry is dehydrated by adding the flocculant to the slurry in a sewage treatment plant. CONSTITUTION:A flocculant is injected in a slurry supply pipe 3 by a flocculant injection pump 6 to perform flocculation reaction and, thereafter, a slurry is dehydrated by a dehydration means 4 to obtain a filtrate 8. The capillary tube suction time (CST) of the filtrate 8 is measured by a CST measuring means 10 and the injection of the flocculant due to a flocculant pump 6 is controlled so as to minimize the CST value.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a slurry for highly efficiently dehydrating a slurry by adding an optimum amount of an organic polymer coagulant to a slurry generated from a treatment facility such as sewage, night soil or industrial wastewater. The present invention relates to a dehydration control method and device.

[0002]

2. Description of the Related Art Generally, for example, in a dehydration process of a slurry in a sewage treatment plant, an organic polymer coagulant (hereinafter, simply referred to as polymer coagulant or simply coagulant) is added to the slurry,
After that, a dehydrated cake is obtained by a dehydrator, and the conventional method of adding a coagulant is described in JP-B-57-
No. 31932 and JP-A-60-25598.

The coagulant addition method described in Japanese Patent Publication No. 57-31932 measures the concentration of raw sludge (slurry) and controls the sludge supply amount and coagulant injection amount based on the measured values. To do.

The method of adding a coagulant disclosed in JP-A-60-25598 is to measure the capillary suction time (hereinafter abbreviated as CST) of the coagulated sludge in the state where the coagulant is added, and the coagulant at that time is measured. From the relationship between the addition amount of CST and CST,
The optimum value is set when ST is shortened, and this is multiplied by a coefficient to determine the addition amount.

By the way, in the former method of measuring the concentration of the raw sludge described above, since the raw sludge is guided to the coagulant addition step through the thickening tank, the concentration changes with the lapse of time, and as a result, it becomes necessary. The addition amount of the coagulant to be added will also vary, but since the addition amount of the coagulant is determined based on the concentration of the raw sludge, it may not be possible to control the appropriate coagulant injection amount.

On the other hand, in the latter method in which the amount of the coagulant added is determined by measuring the CST, the CST tends to decrease as the amount of the coagulant added increases, and the CST increases when the amount exceeds a certain level. .. A small CST means that the sludge flocs are growing large,
From this, there is no doubt that the addition amount of the aggregating agent may be adjusted so that the CST becomes the minimum.

However, in this method, the CST is measured in the state where the coagulant is added, and therefore the amount of flocs in the coagulated sludge sampled is different, which causes a large variation in the measured data, resulting in coagulation. There is a problem that it is difficult to control the addition amount of the agent optimally.

For example, at a certain sewage treatment plant, the CST (seconds) of the coagulant sludge after coagulant injection is divided into the proper coagulant injection state and the excessive coagulant injection state, and a plurality of CST (seconds) measurements are made for the same raw sludge. As a result of repeated times, in the proper injection state, [7.6 seconds, 9.9 seconds, 7.8 seconds, 9.7 seconds, 8.3 seconds].
Second] measurement data was obtained, and [2
1.2 seconds, 13.0 seconds, 13.6 seconds, 19.7 seconds, 1
9.8 seconds] was obtained, and large variations occurred in the measurement data in both the proper injection state and the excessive injection state.

Further, the amount of colloidal charge of sludge is measured in advance, and the index of sludge concentration and sludge property is obtained from the measured value.
A dehydration control method (Japanese Patent Laid-Open No. 61-200899) for controlling conditions such as the amount of sludge, the amount of coagulant supplied, the stirring strength of a mixing tank, the dehydration time, and the dehydration pressure to optimal values based on these values, and sludge coarse A control method for determining the addition ratio by expressing the addition ratio of the coagulant by a linear function of these factors by knowing the suspended solids, the anion content, and the cation content of the coagulant (JP-A-62-1325).
No. 99) has been proposed.

However, in order to measure various factors such as the amount of colloidal charge of sludge, the amount of coarse sludge suspended in the sludge, the degree of anion, and the degree of cation of the flocculant, a high degree of physical and chemical knowledge and experience are required. In addition, the measurement operation is complicated and it takes a considerable amount of time to obtain a result.For example, when first sludge, excess activated sludge, and digested sludge are mixed in a sewage treatment plant, the mixing ratio fluctuates from moment to moment. Therefore, if it is attempted to control the injection amount of the coagulant by using the values of these factors, there is a disadvantage in that the control is inevitably followed.

[0011]

SUMMARY OF THE INVENTION The present invention solves the above problems and provides a slurry dewatering control method and apparatus capable of appropriately adding a flocculant to a slurry to lower the water content of the dehydrated cake. It is intended to be provided.

[0012]

One example of a method for controlling the dehydration of a slurry that achieves the object of the present invention is to successively measure a capillary suction time of a dehydrated filtrate during dehydration treatment after adding a polymer flocculant to a slurry. Then, the addition of the polymer coagulant to the slurry is adjusted so that the measured capillary suction time is minimized.

Further, one example of a slurry dehydration control apparatus for realizing the object of the present invention is a dehydration apparatus for injecting a polymer coagulant into a slurry, and a dehydration for dehydrating the slurry which has undergone an aggregation reaction by injecting the coagulant. In the slurry dehydration system having means, based on the values measured by the dehydration filtrate capillary suction time measuring means for measuring the capillary suction time of the dehydration filtrate from the dehydrating means, and the dehydration filtrate capillary suction time measuring means And a control unit for controlling the coagulant injection unit and controlling the coagulant injection amount.

[0014]

The above-described method for controlling the dehydration of the slurry of the present invention is
The dehydrated filtrate discharged in the dehydrating means may contain a certain amount of fine particles that cannot be normally collected by the dehydrating means, but the dehydrated filtrate collected as a sample does not vary so much between the same samples. Since there is no variation in the value of the capillary suction time of this dehydrated filtrate, and the value that minimizes the capillary suction time of the filtrate is the optimum addition rate, it is possible to extremely accurately inject the appropriate amount of flocculant into the slurry. The slurry can be dehydrated at a low water content.

Further, the above-described slurry dewatering control apparatus of the present invention can perform highly accurate slurry dewatering control with a simple structure of measuring the capillary suction time of the dewatered filtrate.

[0016]

FIG. 1 is a block diagram showing an embodiment of a dehydration control device capable of effectively implementing the slurry dehydration control method according to the present invention.

Reference numeral 1 denotes a slurry storage tank, which is sent to a dehydrating means 4 through a slurry supply pipe 3 by a slurry pump 2 which is constructed so that a remote automatic flow rate can be adjusted. Here, as the dehydrating means 4, a vacuum dehydrator, a pressure dehydrator, a centrifugal separator, a belt press type dehydrator, a screw press or the like is used. Reference numeral 5 denotes a slurry concentration measuring means for measuring the slurry concentration in the slurry supply pipe 3, and a specific example of this concentration measuring means will be described later. The concentration measuring means 5 is provided as needed and may be omitted in some cases.

A coagulant pump 6 is used to inject the coagulant in the coagulant storage tank 7 containing a known organic polymer coagulant into the slurry supply pipe 3, and the injection point is the concentration measuring means 5.
It is located on the downstream side of the location where is placed, and the concentration measuring means can measure the raw sludge. The slurry after the coagulant is injected is then introduced into the coagulant reaction device 13, where the slurry is coagulated and sludge flocs are formed. The flocculant reaction device 13 may be omitted depending on the type of the dehydrating means 4.

By supplying a liquid to be dehydrated containing sludge flocs to the dehydrating means 4, the liquid 8 is separated into a filtrate 8 and a dehydrated cake 9. 10 is a filtrate CST measuring means, and a dehydrating means 4
The CST of filtrate 8 from is measured. Here, the filtrate 8 may contain a certain amount of fine particles that could not be collected by the dehydrating means 4, but the CST measured between the same samples
There will be little variation. Here, although the principle of CST measurement is well known, it will not be described in detail, but in the present embodiment, the apparatus shown in FIG. 2 automatically detects CST.

The apparatus shown in FIG. 2 has an inlet pipe (not shown) and an outlet pipe (not shown) for the filtrate 8, and the valve body (not shown) controlled to automatically open and close the filtrate 8 automatically. The filter paper 102 gripped by the pair of filter paper presser plates 108 is dipped to a predetermined position in the filtrate pot 121 in which the storage is performed (the periphery is covered with the outer container 125 to prevent the dispersion of the filtrate), A pair of electrodes 10 provided on one filter paper restraining plate 108
The time during which the liquid has risen up the filter paper 102 by the capillary suction phenomenon up to 9 minutes is measured by a timing device (not shown), and this is designated as CST (second). After the measurement, the used filter paper is discarded in the adjacent filter paper discard pot 126.
A large number of filter papers 102 are stacked on the stacking plate 115 of the filter paper holder 101, and the air cylinder 114 is driven until the photo sensor 117 detects that the uppermost filter paper has reached a predetermined position. The filter paper 102 at the uppermost position in the horizontal posture is supplied to the filter paper tray 10 by the suction type transport mechanism.
6 is conveyed in a vertical posture and can be held by a pair of filter paper restraining plates 108.

In this suction type transport mechanism, an air cylinder 104 is attached to an arm 119 which is turned by a 90-degree turning actuator 105, and a suction portion 118 is attached to the tip of a cylinder rod 103 thereof. Suction is held by the suction unit 118 (high airtightness is maintained and suction holding property is kept good by sticking a film on the opposite side of the suction of the filter paper), and it is rotated 90 ° and conveyed to the filter paper tray 106. To be done.

The pair of filter paper restraining plates 108 are attached to the pair of air chuck plates 120, respectively, so that the filter paper 102 can be gripped by supplying air to the actuator 107, and by driving the lifting air cylinder 110. Move up and down. In addition, the lifting air cylinder 110
Is movable along a horizontal slide shaft 112 composed of a rodless air cylinder or the like, and by limit switches 222, 223 and 224 provided corresponding to the filter paper sandwiching position, the measuring position and the filter paper discarding position, respectively. It automatically stops at each of the positions. This filtrate CST
Is sequentially performed at regular intervals, and the measurement result is sent to a control means (not shown) to control the coagulant injection amount by the coagulant pump 6.

The CST of the dehydrated filtrate measured automatically
The data of [7] was measured under the same conditions as those shown in the conventional example, and [7.2 seconds, 7.8
Sec., 8.1 sec., 7.6 sec., 7.4 sec.] Was obtained, and [16.6 sec., 16.2 sec.
15.1 seconds, 15.1 seconds, 15.7 seconds] was obtained.

From this, it can be said that the CST has very little variation in measurement of the dehydrated filtrate, and the measurement data has high reliability.

The above-mentioned control means for controlling the optimum addition amount (rate) of the coagulant includes the slurry concentration information from the slurry concentration measuring means 5, the slurry supply amount, the coagulant concentration and the coagulant injection amount by the coagulant pump 6. The coagulant injection amount that minimizes the CST value is obtained by increasing or decreasing the coagulant injection amount that has been input and comparing the front and rear relationships of the respective filtrate CST values at that time.

Further, the addition rate can also be obtained from the slurry concentration value at the same time by the following formula.

Addition rate = (Coagulant injection amount × Flocculant concentration) ÷
(Slurry supply amount × slurry concentration) × 100 These values are stored in a storage unit (not shown) and used for subsequent control.

The relationship between the filtrate CST and the coagulant addition rate obtained based on the data stored in this way, the coagulant addition rate (against TS, where TS is the total solid content in the slurry) 3) and the cake water content are shown in FIG. FIG. 3 shows data obtained by symmetrically arranging the slurry of a certain sewage treatment plant. The graph showing the relationship between the filtrate CST and the coagulant addition rate shown in FIG.
The filtrate CST is the smallest at around 75%, and in the graph showing the relationship between the coagulant addition rate (against TS) and the cake water content shown in (B) of FIG. The water content of the cake is the lowest around 0.75%.

Therefore, the coagulant addition rate at which the filtrate CST is minimized and the coagulant addition rate at which the cake water content is minimized are substantially the same, and both relationship curves are also very similar in their shapes. Recognize.

Next, the control operation of this embodiment will be described. First, an appropriate amount of coagulant is added to the supplied sludge, and the dehydration means 4 starts dehydration. The CST of the filtrate 8 discharged from the dehydrating means 4 by dehydration is measured by the filtrate CST measuring means 10, and the measured value is stored in the control means.

Next, after slightly increasing the addition amount of the coagulant and after a certain period of time, the filtrate CST value is obtained again by the same measurement. If the present value is larger than the previous value, the coagulant addition amount is increased. Although the CST value of the filtrate was increased despite the fact that it was carried out, it is judged that the filtrate was added in excess of the optimum addition rate. Therefore, in this case, the addition amount of the coagulant is reduced.

On the other hand, if the present filtrate CST value becomes larger than the previous filtrate CST value while the coagulant addition amount (rate) is being decreased, the coagulant addition amount is decreased. As a result, the CST value of the filtrate this time has increased, so it is determined that the coagulant is insufficient, and the addition amount (rate) of the coagulant is increased. In this way, the coagulant can be injected at the optimum addition rate by measuring the filtrate CST value at regular intervals and controlling the injection amount of the coagulant so that this value is minimized.

Here, if a control system is adopted in which the supply amount of the coagulant is started from a completely random amount, it takes time to reach the optimum value, and the dehydration treatment during that time becomes inefficient, so the slurry to be treated is inefficient. If the amount of the coagulant to be added to the slurry is determined in advance by a coagulation test or the like according to the properties of the above, the type of coagulant, etc., control in an optimum state can be obtained in a short time.

The relationship between the water content of the dehydrated cake and the addition rate of the coagulant is represented by a quadratic curve as shown in FIG. 3B. As can be seen from this figure, the water content of the dehydrated cake is Even if the addition rate of the coagulant changes slightly within the range around the minimum value of, the water content of the obtained cake does not become extremely high.

Therefore, in the case where it is desired to save the amount of the coagulant used as much as possible, the dehydration means is added at a slightly lower addition rate than the above-mentioned optimum addition rate within a range in which the water content of the obtained dehydrated cake does not become too high. You may drive. The above range is the addition rate obtained by multiplying the addition rate of the coagulant that minimizes the filtrate CST by a constant of approximately 0.7 to 1.0.

As the slurry concentration detecting means 5 for detecting the concentration of the slurry in FIG. 1, means using a gravimetric method, a bubble elimination method, a dielectric constant method, etc. is known. By the way, in a normal slurry dehydration facility, the concentration of the slurry varies with time, day of the week, seasonal variation, etc., and if the amount of the organic polymer coagulant does not increase or decrease in response to the variation in the concentration of the slurry, the best dehydration is possible. No cake water content is obtained.

However, among the above-mentioned concentration detecting means, although the gravimetric method can accurately measure the concentration, it takes a long time to detect the concentration, and the bubble elimination method and the dielectric constant method have many variations in the detected value. It was not suitable for immediate response. Therefore, it is desirable to use the concentration detecting means that enables the instantaneous detection and has a small variation in the detected value.

The concentration measuring device for measuring the concentration of the slurry satisfying such requirements is described below.

That is, as factors showing the properties of the slurry, temperature, viscosity, electric conductivity, hydrogen ion concentration (P
H), particle size distribution, anion degree, CST, etc., but the measuring device described below calculates the slurry concentration by appropriately combining the respective factors of the temperature, viscosity, electric conductivity, and CST of the slurry. The density measuring device is obtained by the following four combinations.

(1) Temperature of slurry, CST of slurry (2) Temperature of slurry, CST of slurry, and electric conductivity of slurry (3) Temperature of slurry, viscosity of slurry and electric conductivity of slurry (4) Slurry Temperature, the viscosity of the slurry, the electrical conductivity of the slurry, the CST of the slurry, the concentration measuring device shown in (1) above, as shown in FIG. 4, for example, an alcohol thermometer, a mercury thermometer or an electric thermometer, etc. The temperature data detected by the temperature measuring means 21 and the CST measuring means 22, for example, the CST value measured by the device shown in FIG. 2 are input to the converter A-1 of the arithmetic unit A, and the arithmetic unit A-2 is used. Calculate the slurry concentration (S
C) is calculated. The calculated density is output to the output unit A-3 for display on a density display device (not shown) or the like,
Further, for example, it is output to the control unit A-4 in order to control the above-mentioned initial addition rate of the coagulant and the like.

The calculator A-2 has a slurry concentration (SC:
%) Is the target variable, the temperature of the slurry (T: ° C) and CST
Multivariate analysis is performed using (C: second) as an explanatory variable. According to the study by the present inventors, the slurry in a certain sewage treatment plant is SC = −2.02 × 10 ⁻² · T + 1.34 × 10 ^An expression of ⁻² · C + 2.08 (Equation 1) was obtained.

Therefore, by inputting this equation into the calculator A-2 of the calculator A in FIG. 4, the slurry concentration can be obtained in substantially real time from the temperature information and the CST information.

FIG. 8 is a diagram showing the relationship between the slurry concentration (calculated value of sludge concentration) measured by the above equation 1 and the slurry concentration (measured value of sludge concentration) measured by a known gravimetric method. The straight line shown by the broken line shows the correlation between the two slurry concentrations. The concentration measuring device according to the present embodiment was able to obtain the measurement accuracy close to the actual measurement value.

FIG. 5 is a block diagram of the slurry concentration measuring device shown in the above (2). The concentration measuring device shown in FIG. 4 is further provided with an electric conductivity measuring means 23 to change the slurry concentration to a target variable. , Slurry temperature, slurry CS
Along with T, the electrical conductivity of the slurry (E _C : μs / cm)
Is used as the explanatory variable, and the slurry concentration is obtained in the same manner as in the concentration measuring device of (1) above by the formula obtained by the multivariate analysis. The electric conductivity (E _C ) of the slurry is measured by a known electric conductivity meter, and this value is input to the arithmetic unit A together with the slurry temperature information and the slurry CST.
Equation 2 obtained by multivariate analysis is input to the arithmetic unit A, and the slurry concentration (SC) is calculated based on the input information.

Here, with respect to the same slurry as the above formula 1, the following formula 2 was obtained by multivariate analysis in this example.

SC = 2.02 × 10 ⁻² · T−1.40 × 10 ⁻³ E _C + 1.14 × 10 ⁻² · C + 5.81 ... (Equation 2) FIG. 9 corresponds to FIG. Similarly, it is a diagram showing the measured value of the sludge concentration measuring device according to the present embodiment with respect to the actually measured value of sludge concentration, and the measurement accuracy is improved compared to FIG. 8.

The sludge concentration measuring device shown in (3) above is
As shown in FIG. 6, the slurry viscosity (N: Cp) is used as an explanatory variable together with the slurry temperature and the slurry electric conductivity, instead of the information on the slurry CST in the apparatus of (3), and the known coaxial axis is used. The viscosity information of the slurry detected by the viscosity measuring means 24 such as a heavy cylinder type rotary viscometer is used together with the temperature information and the electric conductivity information of the slurry, and the arithmetic unit A.
To enter.

Here, for the same slurry as the above-mentioned formula 1, the following formula 3 was obtained by multivariate analysis in this example.

SC = 2.25 × 10 ⁻² · T + 9.36 × 10 ⁻³ N −4.50 × 10 ⁻⁴ · E _C +1.89 ... (Equation 3) FIG. 10 corresponds to FIG. Similarly, it is a diagram showing the measured value of the sludge concentration measuring device according to the present embodiment with respect to the actually measured value of sludge concentration, and the measurement accuracy on the high concentration side is improved compared to the case shown in FIG.

The sludge concentration measuring device shown in (4) above is
As shown in FIG. 7, the temperature, viscosity, electric conductivity and CST information of the slurry are used as explanatory variables, and the equation obtained by the multivariate analysis is input to the arithmetic unit A-2 of the arithmetic unit A,
The slurry concentration is detected from these four types of slurry information.

Here, with respect to the same slurry as the above formula 1, the following formula 4 was obtained by multivariate analysis in this example.

SC = 2.68 × 10 ⁻² · T + 8.47 × 10 ⁻³ N−5.07 × 10 ⁻⁴ · E _C + 7.49 × 10 ⁻³ · C + 1.86 ··· (Equation 4 In this example, as compared with each of the examples (1) to (3) described above, as shown in FIG. 11, it was possible to perform measurement with very little variation from low concentration to high concentration.

The control method described above basically controls the amount of the coagulant added to the slurry by using only the CST value of the dehydrated filtrate as an index. Alternatively, the coagulant is added. It is also possible to optimally control the addition amount of the coagulant by using the CST value of both the CST value of the previous slurry itself and the CST value of the dehydrated filtrate. This will be described in detail below.

FIG. 12 shows the CST value of the slurry and the CS of the filtrate.
An example of a slurry dehydration control device that controls the addition amount of a coagulant by using both T values is shown, and measuring the CST of a dehydrated filtrate is the same as the example shown in FIG. It is the same.

Reference numeral 11 denotes a slurry CST measuring means using the same device as that shown in FIG. 2, and outputs slurry CST information measured over time to the flocculant addition controller 12.
As in the case of FIG. 1, the controller 12 contains C of the dehydrated filtrate.
The filtrate CST information from the CST measuring means 10 for detecting ST is also inputted, and the reduction rate of the slurry CST described later is calculated from both of these CST information, and thereby the coagulant injected from the coagulant pump 6 into the slurry supply pipe 3 is calculated. Is controlled so that the slurry reacts with the flocculant by the flocculation reaction device 13.

The controller 12 calculates the reduction rate of the slurry CST and controls the coagulant pump 6 so that the reduction rate of the slurry CST becomes maximum.

Here, the CST reduction rate (%) of the slurry
Is (CST value of slurry-CST value of filtrate) / C of slurry
ST value × 100 (Equation 5). For example, for the same slurry from which the data of FIG. 3 was obtained, the coagulant addition rate has the relationship shown in FIG.

In FIG. 13, the reduction rate of the slurry CST is the maximum when the coagulant addition rate is around 0.75%, and this addition rate is the addition rate at which the cake water content becomes the minimum in FIG. 3 (B). They are almost the same.

Therefore, if the coagulant addition rate is controlled so that the slurry reduction rate is maximized, the water content of the dehydrated cake is minimized, and efficient coagulant addition control can be performed.

The control operation of this embodiment is performed until the slurry CST detected by the slurry CST measuring means 11 is input to the controller 12, the coagulant is added to the supplied sludge, and the sludge is discharged as the filtrate 8 by the dehydrating means 4. Wait for the time, filtrate CS
The filtrate CST is measured by the T measuring means 10. Controller 1
2 calculates the reduction rate of the slurry CST from the above equation 5 based on the slurry CST value and the filtrate CST value, and stores this.

Next, the amount of the flocculant added was slightly increased, and after a certain period of time, the slurry C was again measured by the same measurement and calculation.
The reduction rate of ST is calculated, and compared with the previous value. When this value is smaller than the previous value, the reduction rate of slurry CST has decreased even though the coagulant was added excessively. It is judged that the amount added is in excess of the optimum addition rate.
Therefore, in this case, the amount of the coagulant added is reduced. On the other hand, if the slurry reduction rate of this time becomes smaller than the previous slurry reduction rate while the addition amount (rate) of the flocculant is decreased, the slurry CST of this time is reduced by reducing the addition amount of the flocculant. Since the reduction rate has become small, it is determined that the coagulant is insufficient, and the coagulant addition rate is increased. In this way, the slurry CST reduction rate is calculated at regular time intervals, and the coagulant injection amount is controlled so that this value becomes maximum, whereby the coagulant can be injected at the optimum addition rate.

In this embodiment, there is a time difference between the measurement point of the slurry CST and the measurement point of the filtrate CST, but it is possible to measure both CSTs by shifting the time between them and to ignore the difference. If possible, you may measure simultaneously.

In order to save the addition rate of the coagulant as much as possible, it is possible to control the operation at an addition rate slightly smaller than the addition rate at the maximum reduction rate.
This is the same as the case of the control method based only on the filtrate CST value described above.

14 and 15 show another embodiment of the automatic capillary suction time measuring device.

The automatic capillary suction time measuring device of this embodiment is composed of a continuous roll-shaped filter paper 301 rotatably mounted on a turntable and a filter paper drawer for pulling out the filter paper 301 by a sensor device 303 in a fixed amount. A means 302 and a filter paper holding means 3 for holding the filter paper 301 pulled out by the filter paper pulling means 302 from both sides.
04 and a filter paper cutting means 30 for cutting the filter paper 301 held by the filter paper holding means 304 into a predetermined size.
5 and three electrodes 30 attached to one holding surface 307 of the pair of filter paper holding plates 306 forming the filter paper holding means 304.
8A, 308B, 308C and the filter paper holding means 304
A rotatable support arm 309 attached with the support arm 309, an elevating means 310 for vertically moving the support arm 309, and the cut filter paper 3 vertically moved by the elevating means 310.
01 and a sample pot 311 for containing the sample to be measured. A reference numeral 312 denotes a filter paper discard pot for discarding the filter paper 301 after the measurement.

First, the filter paper 301 used in this embodiment is
As shown in FIG. 14, it is in the form of a continuous roll and is set on a turntable 314 attached to the upper surface of the pedestal 313. 315 in the figure is the turntable 14
A central axis 316 of the filter paper holder 316 also serves as a guide for the filter paper 301.

Next, the filter paper pull-out means 302 is attached near the outlet portion 317 of the filter paper holder 316, and the roll-shaped filter paper 301 is pulled out by a predetermined amount by a sensor device 303 including, for example, a light emitting element 318A and a light receiving element 318B. Act. The filter paper pull-out means 302 of the illustrated embodiment is a drive roller 319A and a pressing roller 319 that abuts against the drive roller 319A with an appropriate pressure.
It consists of B and. Note that the drive roller 319A may use a stepping motor or the like that automatically stops when receiving a detection signal from the sensor device 303 as a drive source (not shown). Further, the stepping motor may be automatically stopped after the driving roller 319A is rotated a predetermined number of times, or separately from the stepping motor, the rotation shaft fixed to the turntable 314 is connected to the stepping motor via a pulley and a V-belt. For example, it may be directly driven to rotate. When the delivery of the filter paper is stopped, the filter paper holding means 3 receives this signal.
04 is activated, and a pair of filter paper restraining plates 306,
Hold down by 306. A pair of filter paper press plates 30
The separating / connecting drive devices 6, 306 are not shown.

Next, a filter paper cutting means 305 is attached between the filter paper drawing means 302 and the sensor device 303,
The filter paper 301 is cut into a predetermined size by a pair of cutting blades when the filter paper 301 is stopped after a certain amount of the filter paper 301 is pulled out. Usually, the cut filter paper 301 is cut into a strip shape ( The drive unit of the filter paper cutter is not shown). In addition, in this cutting, filter paper 3
01 is a pair of filter paper pressing plates 306, 306 as described above.
Since both sides are clamped by the pair of cutting blades, they are accurately cut by a pair of cutting blades. For example, the strip-shaped filter paper 301 cut after the cutting process is still held by the filter paper sandwiching means 304. Has become.

First, a pair of electrodes 308A and 308B are provided at the same height position on one holding surface of a pair of filter paper holding plates 306, 306 forming the filter paper holding means 304. An electrode 308C is provided directly above and spaced apart by a predetermined distance. In addition, strip-shaped filter paper 3
In order to hold 01 in a stable state, the holding surface of the filter paper is provided with a dummy holding protrusion 322 at the same height as the protruding height of the electrode 308C and directly above the electrode 308B. An electrode may be attached instead of the restraining protrusion 322. It goes without saying that the electrodes 308A, 308B, 308C are electrically connected to a timing device (not shown).

Next, the support arm 309 to which the filter paper holding means 304 is attached at the front end can be rotated by a drive device 320 such as a stepping motor or an air-operated rotary actuator. That is, in the illustrated embodiment, the rotary shaft 321 of the drive device 320.
The support arm 309 is attached to the support arm 309, and when the drive device 320 starts operation, the support arm 309 rotates, for example, clockwise by a certain angle, and stops at a predetermined position by the operation of the limit switch. It goes without saying that the filter paper holding means 4 holding the strip-shaped filter paper 301 also rotates together with the rotation of the support arm 309.

The lifting means 310 for moving the support arm 309 up and down is the same as the support arm 30 in the illustrated embodiment.
Although it is an air cylinder that raises and lowers the drive device 320 itself that rotates the motor 9, it may be driven by a motor. Also, the lifting means 3
A sample pot 311 containing a sample to be measured such as sludge is prepared below the cut strip-shaped filter paper 301 that moves up and down by 10. Sample pot 3
In the illustrated embodiment, two units 11 are provided, but it is of course possible to provide only one unit. Further, a waste pot 312 for the used filter paper is disposed adjacent to the sample pot 311 in the circumferential area in which the support arm 309 rotates.

Next, a description will be given of an example of use of the apparatus of this embodiment. In the continuous roll-shaped filter paper 301 set on the turntable 314 of the mount 313, the drive roller 319A forming the filter paper pull-out means 302 rotates. When started, the filter paper holder 316 is gradually pulled out from the outlet portion 317. When the light-emitting element 318A and the light-receiving element 318B forming the sensor device 303 are pulled out, the stepping motor, which is the drive source of the drive roller 319A, automatically stops the operation in response to the detection signal from the sensor device 303.

Next, a pair of filter paper pressing plates 3 forming filter paper sandwiching means 304 located in front of the sensor device 303.
06 and 306 close the gap and hold down both sides of the filter paper 301. The filter paper 301 by the filter paper sandwiching means 304
When the pressure is suppressed, the operating device that operates the filter paper cutting means 305 starts operating, and the filter paper 3 is moved by the pair of cutting blades.
Cut 01 exactly. When the filter paper 301 is cut,
The drive device 320 of the support arm 309 to which the filter paper holding means 4 is attached starts operation, and the support arm 309 is rotated clockwise as indicated by the arrow in FIG.
At 1, the rotation is automatically stopped. Strip-shaped filter paper 3
01 is sandwiched on both sides by the filter paper restraining plates 306, 306 forming the filter paper sandwiching means 304 as described above, and rotates together with the support arm 309, and is positioned directly above the sample pot 311 in this state. Become.

When the rotation of the support arm 309 is stopped, the raising / lowering means 310 starts its operation this time, and the support arm 309
Is lowered for a certain distance so that the lower end of the strip-shaped filter paper 301 is immersed in the sample to be measured in the sample pot 311 such as sludge to a certain depth. The filter paper 301 having a certain depth in the sludge has a liquid absorbing property, and the liquid component in the sludge advances above the filter paper 301 by the capillary suction phenomenon and is attached to the lower part of the filter paper restraining plate 306. Pair of electrodes 308A, 3
It reaches 08B. When the liquid content in the sludge reaches the electrodes 308A and 308B, these electrodes are brought into conduction, and a timing device (not shown) starts counting. Further, when the liquid component in the sludge further advances above the filter paper 301 and reaches the upper electrode 308C, the counting is stopped.

The time from the start of counting to the stop of the timer is stored in the timer and can be output by a printer or the like.

When an electrode is provided instead of the dummy restraining protrusion 322, the counting of the timing device is stopped when the liquid component in the sludge reaches either the electrode or the electrode 308C. To configure.

When the measurement is completed, the elevating means 310 starts to operate and the supporting arm 30 to which the filter paper holding means 304 is attached.
9 is raised to a certain height, and the driving device 320 further rotates the support arm 309 in the clockwise direction and stops it at the filter paper waste pot 312. Next, the filter paper holding plates 6 and 6 forming the filter paper holding means 304 attached to the tip of the support arm 309 are pulled apart to remove the used filter paper 301.
Is dropped into the filter paper discard pot 312.

When this series of operations is completed, the support arm 3
Reference numeral 09 is a device that rotates counterclockwise by the drive device 320, returns to the original position, and enters a standby state.

In this embodiment, the electrodes are provided only on one holding surface of the pair of filter paper holding plates forming the paper holding means. However, for example, the electrodes 308A and 308B are provided on one holding surface and the electrode 308C is provided on the other holding surface. It may be attached to the restraining surface of No. 3, or to one restraining surface in the same manner as in the present embodiment.
It is also possible to attach three electrodes and also attach three electrodes to the other restraining surface at positions opposite to the attachment positions of the three electrodes.

The automatic device for measuring capillary suction time according to the present embodiment has the above-described structure and operation, and can solve the problems associated with the conventional device for measuring capillary suction time by the CST method. In particular, a continuous roll of absorbent filter paper is used, and this is cut into a predetermined size for measurement, so that the time and effort of filter paper replenishment can be greatly saved,
Since all the processes are automated, the measurement work can be performed very efficiently.

[0081]

As described above, according to the present invention,
The CST of the filtrate with high measurement accuracy is measured, and the injection amount of the flocculant into the slurry is controlled based on this value. Therefore, the slurry with the optimum flocculant addition state without excessive addition in the state of the lowest water content is used. Dehydration can be performed.

Also, the CS of the slurry along with the CST of the filtrate
By using T for control, it is possible to obtain the effect that optimum coagulant injection control can be performed, and that changes in slurry properties such as changes in slurry concentration can be constantly monitored.

In addition, the CST of the slurry can be measured by a simple structure in which the CST of the filtrate is measured, or at most.
By adding the structure of ST measurement, highly accurate coagulant injection control can be performed.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a slurry dehydration control device according to the present invention.

FIG. 2 is a perspective view of a filtrate CST measuring device.

FIG. 3 is a diagram showing a relationship between a filtrate CST and a coagulant addition rate (A), and a cake water content and a coagulant addition rate (B).

FIG. 4 is a block diagram of a concentration measuring device.

FIG. 5 is a block diagram of a concentration measuring device.

FIG. 6 is a block diagram of a concentration measuring device.

FIG. 7 is a block diagram of a concentration measuring device.

FIG. 8 is a diagram showing a relationship between a calculated sludge concentration value and an actually measured sludge concentration value.

FIG. 9 is a diagram showing a relationship between a calculated sludge concentration value and an actually measured sludge concentration value.

FIG. 10 is a diagram showing a relationship between a calculated sludge concentration value and an actually measured sludge concentration value.

FIG. 11 is a diagram showing a relationship between a calculated sludge concentration value and an actually measured sludge concentration value.

FIG. 12 is a block diagram showing another embodiment of the slurry dehydration control device according to the present invention.

FIG. 13 is a diagram showing a relationship between a slurry CST reduction rate and a coagulant addition rate.

FIG. 14 is a plan view showing another embodiment of the automatic capillary suction time measuring device.

FIG. 15 is a front view of the device shown in FIG.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Slurry storage tank 7 ... Flocculant storage tank 2 ... Slurry pump 8 ... Filtrate 3 ... Slurry supply pipe 9 ... Dehydration cake 4 ... Dehydration means 10 ... Filtrate C
ST measuring means 5 ... Slurry concentration measuring means 11 ... Slurry CST measuring means 6 ... Flocculant pump 12 ... Controller

Front page continuation (72) Inventor Noboru Okazaki 3-19-7-108 Kamiishakuji, Nerima-ku, Tokyo (72) Inventor Kozaburo Akamatsu 676 32-32, Asahimachi, Funabashi, Chiba (72) Inventor Tomoyuki Hayashi Saitama Pref. 1-4-9 Kawagishi, Toda City, Tochigi Prefecture Organo Research Institute (72) Inventor Tomohiko Kusumi 1-4-9, Kawagishi, Toda City Toda City, Saitama Pref. Organo Research Institute

Claims (5)

[Claims] 1. When adding a polymer coagulant to the slurry and then performing a dehydration treatment, the capillary suction time of the dehydrated filtrate is sequentially measured, and a slurry of the polymer coagulant is added so that the measured capillary suction time is minimized. A method for controlling dehydration of a slurry, which comprises adjusting the addition of water. 2. The polymer according to claim 1, wherein the addition ratio of the polymer flocculant that minimizes the capillary suction time of the dehydrated filtrate of the slurry to be treated is multiplied by a constant of 0.7 to 1.0. A method for controlling the dehydration of a slurry, which comprises adjusting the addition of a flocculant to the slurry. 3. A capillary suction time of the slurry and a capillary suction time of the dehydrated filtrate are sequentially measured in the dehydration treatment after adding the polymer coagulant to the slurry, and the capillary suction time of the slurry and the capillary suction of the dehydrated filtrate are sequentially measured. A method for controlling dehydration of slurry, which comprises calculating a reduction rate of a capillary suction time of a slurry from a suction time and adjusting the addition of a polymer coagulant so that the reduction rate of the capillary suction time is maximized. 4. A dehydration system for a slurry, comprising a coagulant injecting means for injecting a polymer coagulant into a slurry and a dehydrating means for dehydrating the slurry which has undergone an agglutination reaction by injecting the coagulant. Dehydration filtrate capillary suction time measuring means for measuring the capillary suction time of the filtrate, and controlling the coagulant injecting means based on the value measured by the dehydration filtrate capillary suction time measuring means to control the coagulant injection amount. And a control means for controlling the dewatering of the slurry. 5. A slurry suction system comprising a flocculant injecting means for injecting a polymer flocculant into the slurry and a dehydrating means for dehydrating the slurry which has undergone an agglutination reaction by injecting the flocculant Slurry capillary suction time measuring means for measuring, dehydrated filtrate capillary suction time measuring means for measuring capillary suction time of dehydrated filtrate, and controlling the coagulant injecting means based on the measured values from both capillary suction time measuring means And a control means for controlling the injection amount of the coagulant,
The control means successively calculates the reduction rate of the slurry capillary suction time from the slurry capillary suction time and the dehydrated filtrate capillary suction time, and controls the injection of the flocculant based on this value, thereby controlling the dehydration of the slurry. apparatus.