JPH0351443B2 - - Google Patents

Description

[Detailed Description of the Invention] (1) Purpose of the Invention [Field of Industrial Application] The present invention relates to a method for controlling agitation in a flocculate formation pond, and in particular, the present invention relates to a method for controlling agitation in a flocculation pond, and in particular, the present invention relates to a method for controlling agitation in a flocculation pond, and in particular, the present invention relates to a method for controlling agitation in a flocculation pond, and in particular, the present invention relates to a method for controlling agitation in a flocculation pond, and in particular, the present invention relates to a method for controlling agitation in a flocculate formation pond, and in particular, the present invention relates to a method for controlling agitation in a flocculate formation pond, and in particular, the present invention relates to a method for controlling agitation in a flocculate formation pond, and in particular, the present invention relates to a method for controlling agitation in a flocculate formation pond, and in particular, the present invention relates to a method for controlling agitation in a flocculation pond, and in particular, a flocculant is injected into a collected suspension while stirring. By detecting the velocity gradient and the flocculation time at which the agglomerate is formed, as well as the amount of suspension supplied to the mixing basin and the volume of the flocculate basin, the agitation control in the flocculate basin is performed. The present invention relates to a stirring control method for an aggregate formation pond.

[Prior Art] Conventionally, as a stirring control method for this type of aggregate formation pond, a flocculant is injected in a mixing basin that performs rapid stirring, and then aggregates are formed in an aggregate formation pond that performs slow stirring. A suspension of tap water, industrial water, sewage, industrial waste liquid, etc. is actually collected in a beaker, and the condition of aggregate formation is determined by visual observation and experience of the tester. It has been proposed to adjust the stirring control in

[Problems to be solved] However, in the conventional agitation control method for the aggregate formation pond, the agitation process in the aggregate formation pond was determined based on visual observation and experience of the tester. There is a drawback that the results are different and it is not possible to optimize the agitation process in the aggregate formation pond.
Since it takes more than a minute, it takes a lot of time to judge the state of aggregate formation and has the disadvantage that it is not possible to respond immediately to changes in the suspension.At the same time, the stirring control in the aggregate formation pond cannot be performed with high precision. is not possible, especially if the aggregate formation pond is divided into multiple areas.
There was also the drawback that once formed aggregates were destroyed by agitation in subsequent regions.

Therefore, in order to eliminate these drawbacks, the present invention calculates the aggregate formation time and velocity gradient when a flocculant is injected into the sampled suspension at a predetermined injection rate, and determines the aggregate formation time and velocity gradient accordingly. It is an object of the present invention to provide a method for controlling agitation of an aggregate formation pond in which agitation of the pond is controlled.

(2) Structure of the invention [Means for solving the problem] The first means for solving the problem provided by the present invention is as follows: ``After injecting a flocculant into the suspension while rapidly stirring it in a mixing basin, In an agitation control method for an aggregate formation pond in which aggregates are formed by slow stirring in an aggregate formation pond, (a) a flocculant is injected into the suspension collected upstream of the mixing basin; The first step is to stir the mixture in the stirring tank.
(b) a second step of stirring the flocculant-injected suspension in the first step at a lower stirring speed than in the first step; and (c) in the second step. (d) at least in the second step, the amount of light received by the light emitting device to the light receiving device via the suspension into which the flocculant was injected in the first step; (e) a fifth step of determining the aggregate formation time of the suspension in which the flocculant was injected in the first step from the amount of received light measured in the fourth step; (f) a sixth step of detecting the amount of suspension supplied to the mixing pond; (g) the velocity gradient determined in the third step, the aggregate formation time determined in the fifth step, and the sixth step; a seventh step of controlling agitation in the aggregate forming pond using the supplied amount of suspension detected in the above and the volume of the aggregate forming pond. ``Stirring control method''.

The second solution to the problem provided by the present invention is to inject a flocculant into the suspension while rapidly stirring it in a mixing pond, and then flocculate it by slowly stirring it in a flocculation pond. In an agitation control method for an agglomerate formation pond formed by forming an agglomerate, (a) a first step of injecting a flocculant into a suspension collected upstream of the mixing pond and stirring it in an agitation tank;
(b) a second step of stirring the flocculant-injected suspension in the first step at a lower stirring speed than in the first step; and (c) in the second step. (d) at least in the second step, the amount of light received by the light emitting device to the light receiving device via the suspension into which the flocculant was injected in the first step; (e) a fifth step of detecting the agglomeration state of the suspension into which the flocculant was injected in the first step from the amount of received light measured in the fourth step; f) A sixth step of determining, from among the velocity gradients determined in the third step, a velocity gradient that makes the agglomeration state detected in the fifth step appropriate as an appropriate velocity gradient; (h ) an eighth step of detecting the amount of suspension supplied to the mixing pond; (i) detecting the appropriate velocity gradient determined in the sixth step and the seventh step;
The appropriate aggregate formation time determined in the step 8 and
and a ninth step of controlling stirring in the aggregate formation pond using the supply amount of the suspension detected in the step and the volume of the aggregate formation pond. ``Method for controlling agitation in a formation pond.''

[Function] The first stirring control method of the flocculation pond according to the present invention is to inject the flocculant into the suspension while rapidly stirring it in the mixing basin, and then slowly stirring it in the flocculation basin. In a stirring control method for an aggregate formation pond in which aggregates are formed by The amount of received light given from the light emitting device to the light receiving device through the suspension injected with the flocculant is measured, and the aggregate formation time is detected from this amount of received light, and the suspension in the mixing basin is detecting the supply amount of the aggregate formation pond, and controlling the agitation of the aggregate formation pond according to the aggregate formation time and velocity gradient, the supply amount of the suspension, and the volume of the aggregate formation pond. This has the effect of eliminating the visual observation and experience of the tester, and also has the effect of optimizing the agitation control of the aggregate formation pond in a short time while avoiding actually measuring the progress of the agitation process in the aggregate formation pond. Eggplant.

In addition, the second agitation control method of the flocculate formation pond according to the present invention is that after injecting the flocculant into the suspension while stirring rapidly in the mixing basin, the flocculant is injected into the suspension and then slowly stirred in the flocculation basin. In a stirring control method for an aggregate formation pond formed by forming aggregates, a flocculant is injected into a collected suspension, the stirring speed is lowered, and a velocity gradient corresponding to the lowered stirring speed is determined, Measure the amount of light received by the light receiving device from the light emitting device through the suspension injected with the flocculant, and detect the agglomeration state of the suspension in which the flocculant is injected from the amount of received light. Of the velocity gradients, the velocity gradient that makes the agglomeration state appropriate is determined as the appropriate velocity gradient, and the agglomerate formation time of the suspension injected with the flocculant is determined in accordance with the appropriate velocity gradient to form the appropriate agglomerates. The amount of suspension supplied to the mixing pond is detected as the formation time, and the amount of the flocculation is determined according to the appropriate aggregate formation time, the appropriate velocity gradient, the amount of suspension supplied, and the volume of the aggregate formation pond. It functions to control the agitation of the aggregate formation pond,
In addition to the effect of eliminating the visual observation and experience of the tester and the effect of optimizing the agitation control of the agglomerate formation pond in a short time while avoiding the actual measurement of the results of the agitation process in the agglomerate formation pond, It functions to execute stirring control in the formation pond with high precision.

[Example] Next, the present invention will be specifically described with reference to the accompanying drawings.

FIG. 1 is a sectional view showing an actual suspension processing apparatus in which agitation control of an agglomerate formation pond is executed by an embodiment of the agitation control method for an agglomeration formation pond according to the present invention.

FIG. 2 is a cross-sectional view specifically showing an example of the detection device of FIG. 1 for detecting the velocity gradient G _t and the aggregate formation time T _t in order to carry out an embodiment of the present invention.

FIG. 3 is an operational explanatory diagram for explaining the operation of the detection device shown in FIG.
It shows the change over time.

FIG. 4 shows the method of FIG. 1 for detecting an appropriate speed gradient G _t ^* and an appropriate aggregate formation time T _t ^* in order to carry out an embodiment of another stirring control method for an aggregate formation pond according to the present invention. FIG. 2 is a cross-sectional view specifically showing an example of a detection device.

FIG. 5 is a graph showing the relationship between the diameter d, number N _b , volume V, and effective density ρ of the aggregate detected by the detection device of FIG. 4 and the velocity gradient G _t .

FIG. 6 is a graph showing the relationship between supernatant water turbidity τ, aggregate sedimentation velocity S and effective density ρ detected by the detection device of FIG. 4, and velocity gradient G _t .

FIG. 7 is a sectional view showing a detection device in which four detection devices of FIG. 4 are arranged side by side.

First, with reference to FIG. 1, an actual suspension processing apparatus in which agitation control of an agglomerate formation pond is executed by the agitation control method for an agglomeration formation pond according to the present invention will be described.

Reference numeral 102 denotes a landing well, into which a suspension is supplied via a supply pipe 104 from an appropriate suspension supply source (not shown). 106 is the supply pipe 1 for the landing well 102
A stirring blade 110 that is rapidly rotated by a driving means such as an electric motor 109 is disposed in the mixing pond for the suspension and the flocculant, which are communicated through the mixing tank 08 .

Reference numeral 112 denotes an aggregate forming pond which is communicated with the mixing basin 106 via a supply pipe 114, and is divided into a desired number of regions, for example, three regions 112A, -, 112C, each having a volume of V _A , -, V _C . Agitators 113A, . . . , 113C are provided respectively. Stirrer 113A, ~, 113C
are each driven by a driving means such as an electric motor 115.
A, . . . , 115C, and a rotation speed n _A , by means of a drive means such as an electric motor 115A, .
~, n Stirring blade 116A rotated slowly at _C , ~,
116C. The suspension in which the flocculant is injected and mixed in the mixing basin 106 and supplied to the flocculation basin 112 through the supply pipe 114 is first fed to the first area of the flocculation basin 112, that is, the first area 112A. The stirring blade 116A of the stirrer 113A slowly stirs the mixture at a rotation speed _nA for a predetermined time, and then the mixture is transferred to the second area 112B and is slowly stirred at a rotation speed _nB for a predetermined time by the stirring blade 116B of the stirrer 113B. It is stirred at high speed, and then transferred to the third region 112C and stirred by the stirrer 113C.
The mixture is slowly stirred by the stirring blade 116C at a rotational speed _nC for a predetermined period of time.

Reference numeral 118 denotes a sedimentation tank connected to the flocculation basin 112, in which the suspension supplied from the final area, ie, the third area 112C, of the flocculation basin 112, and in which flocs have been sufficiently formed, is kept still. The aggregates, or flocs, are precipitated and removed. Reference numeral 120 denotes a filter tank that is connected to the outlet of the sedimentation tank 118 via a supply pipe 122, and after removing fine aggregates, that is, flocs that could not be removed in the sedimentation tank 118, the water is passed through the treated water pipe 124 as treated water. It is sent to the appropriate subsequent equipment.

130 is specifically shown in FIG. 2, and is a detection device for outputting the velocity gradient G _t and aggregate formation time T _t when the flocculant is injected into the suspension at a predetermined injection rate. The device is connected to the landing well 102 via a supply pipe 132 and a pump 134, and a discharge pipe 133 is opened to an appropriate location such as a mixing basin 106.

136 is a flow meter 13 arranged in the supply pipe 108
8 and the detection device 130, each of which calculates the speed gradient detected by the detection device 130.
G _t , the aggregate formation time T _t , the flow rate detected by the flow meter 138 (that is, the amount of supply to the mixing basin 106), and the flow rate of the aggregate formation basin 112 measured in advance and inputted by manual operation etc. Each area 112
A, ~, 112C receive necessary information such as the volumes V _A , ~, V _C , and use this information to create agitators 113A, ~, 113A, ~, disposed in each region 112A, ~, 112C of the aggregate formation pond 112, respectively. 113C's rotational speed n _A , ~, n _C is calculated.

That is, the calculation device 136 calculates the velocity gradient G _t and aggregate formation time given by the detection device 130.
The relationship between T _t , the velocity gradient G _r in the aggregate formation pond 112, and the aggregate formation time T _r (however, α
is a constant) T _t /T _r [G _t /G _r ] ^1/2 = 1/α, each area 112A of the aggregate formation pond 112,
Velocity gradient G _r (A) at ~, 112C, ~, G _r (C)
From G _r (A)=α _A G _r G _r (B)=α _B G r G _r ( _C )=α _{C G r} using constants α _A , ~, α C, the velocity gradient G _r (A ), ~, G _r (C), G _r (A)=α _A [αT _t /T _r ] ² G _t G _r (B)=α _B [αT _t /T _r ] ² G _t G _r (C )=α _C [αT _t /T _r ] ² G _t . However, the constants α _A , ~, α _C are
Each region 112A, ~, 11 of the aggregate formation pond 112
Considering the stirring intensity at 2C, α _A ≧ α _B ≧ α _C , and V _A α _A ² + V _B α _B ² + V _C α _C ² = V _A + V _B + V _C. Here, each region 112A, ~, 112C of the aggregate formation pond 112 has an equal volume, that is,
If V _A = V _B = V _C , there is a relationship between the constants α _A , . . . , α _C as follows: α _A ² + α _B ² + α _C ² = 3.

The velocity gradient G _r (A), ~, G _r (C) is the viscosity coefficient μ and specific gravity η of the suspension, the drag coefficient C, and the stirrer 113
A, ~, 113C stirring blades 116A, ~, 11
6C area a _A , ~, a _C and circumferential speed υ _A , ~, υ _C and each area 112A, ~, 112 of aggregate formation pond 112
Using the volumes V _A , ~, and V C of C, G _r ( _A ) = [Cηa _A υ _A ³ /2μV _A ] ^1/2 G _r (B) = [Cηa _B υ _B ³ /2μV _B ] ^{1 /2} G _r (C) = [Cηa _C υ _C ³ /2μV _C ] ^1/2 , so from this relationship a _A υ _A ³ =2μV _A /CηG _r (A) ² a _B υ _B ³ = 2μV _B /CηG _r (B) ² a _C υ _C ³ = 2μV _C /CηG _r (C) ² can be calculated. Here, the stirring blade 116A, ~, 1
The circumferential speed υ _A , ~, υ _C of 16C is calculated using the rotational speed n _A , ~, n _C and radius r _A , ~, r _C , υ _A = 2πr _A n _A υ _B = 2πr _A n _A υ _C = 2πr _A n _A , and therefore a _A υ _A ³ , ~, a _C υ _C ³ can be expressed as a _A υ _A ³ = 8a _A π ³ r _A ³ n _A ³ a _B υ _B ³ = 8a _B π ³ r _B ³ n _B ³ a _C υ _C ³ = 8a _C π ³ r _C ³ n _C ³ , so 8a _A π ³ r _A ³ n _A ³ = 2μV _A /CηG _r (A) ² 8a _B π ³ r _B ³ n _B ³ = 2μV _B /CηG _r (B) ² 8a _C π ³ r _C ³ n _C ³ = 2μV _C /CηG _r (C) ² , and the rotation speed n _A , ~, n _C n _A = [2μV _A G _r (A) ² /8a _A π ³ r _A ³ Cη] ^1/3 n _B = [2μV _B G _r (B) ² /8a _B π ³ r _B ³ Cη] ^1/ It can be calculated as ³ n _C = [2μV _C G _r (C) ² /8a _C π ³ r _C ³ Cη] ^1/3 . Therefore, the rotational speed n _A , ~n _C is n _A = [μV _A α ⁴ α _A ² G _t ² T _t ⁴ /4a _A π ³ r _A ³ CηT _r ⁴ ]
^1/3 n _B = [μV _B α ⁴ α _B ² G _t ² T _t ⁴ /4a _B π ³ r _B ³ CηT _r ⁴ ]
^1/3 n _C = [μV _C α ⁴ α _C ² G _t ² T _t ⁴ /4a _C π ³ r _C ³ CηT _r ⁴ ]
It can be calculated as ^1/3 . However, T _r is (V _A + V _B + V _C )/
It is Q. As a result _{, the} rotational speed n _{A , .} 138 can be determined by the flow rate Q) sensed by

140 is a rotation speed controller connected to the calculation device 136, which controls the agitators _113A , . . . , ₁₁ according to the rotation speeds nA, .
The rotation speed of the drive means 115A to 115C of 3C is controlled. 144 is a coagulant supply device, which supplies a coagulant to a pipe 146 according to a preset injection rate W _A1 .
The suspension is supplied to the mixing pond 106 via the mixing pond 106 and injected into the suspension.

Therefore, the detection device 130 according to the present invention is connected to the landing well 1 through the pump 134 and the supply pipe 132.
The suspension is collected from 02, and the flocculant supply device 1
_For example, the velocity gradient G _t and aggregate formation time T _t when the flocculant is injected at the same injection rate are output as described below.

Velocity gradient of the suspension detected by the detection device 130
G _t and aggregate formation time T _t are originally given to the arithmetic unit 136 . In the arithmetic unit 136,
Each time the velocity gradient G _t and the aggregate formation time T _t are input from the detection device 130, each region 112A of the aggregate formation pond 112,
~, 112C, respectively, are provided with agitators 113
The rotational speeds n _A , . . . , n _C of A, .about., 113C have been calculated.

The rotational speed n _A outputted from the arithmetic unit 136, ~,
n _C is given to the rotation speed controller 140. The rotation speed controller 140 controls the agitators 113A, 113A, and 113A of the aggregate formation pond 112 according to the rotation speeds n _A , ~, n _C, respectively.
~, 113C are driven. Here, aggregate formation pond 1
12 is supplied with a suspension prepared in a mixing pond 106 and having a flocculant injection rate of W _A1 .

By intermittently repeating the detection operation by the detection device 130 described above, aggregate formation in the suspension processing device can be performed with appropriate efficiency, and the processing time of the suspension can be shortened.

Further, the configuration of the detection device 130 will be explained in detail with reference to FIGS. 2 and 3.

Reference numeral 10 denotes a batch-type stirring tank, which has an appropriate capacity, for example, 1, and contains a suspension (hereinafter sometimes simply referred to as suspension) 1 into which a flocculant has been injected.
1 is accommodated. Reference numeral 12 denotes a stirring blade disposed in the stirring tank 10, which is connected to the output shaft 16 of a drive means, for example, an electric motor 14, arranged below the stirring tank 10.
is suitably attached to the free end of the

A light emitting device 18 is connected to a suitable power source (not shown) by a lead wire 19, and is disposed on the side of the stirring tank 10, and can be used for fluorescent lamps, tungsten lamps, halogen lamps, light emitting diodes, and laser light emitting devices. The light generated by a suitable light source such as a light source is converted into a parallel beam bundle through a suitable optical system, such as a slit, and is supplied to the suspension 11 in the stirring tank 10. Reference numeral 20 denotes a light receiving device that includes a suitable photoelectric conversion element such as a phototransistor, photodiode, CdS, or CCD as a light receiving means.
The light emitting device 18 receives light supplied as a bundle of parallel light rays via the suspension 11. Since the light provided by the light emitting device 18 is scattered or blocked by the aggregates or flocs 17 in the suspension 11, the light receiving device 20 receives the scattered light or attenuated transmitted light. There is. The light receiving device 20 may be placed opposite the light emitting device 18 in order to receive transmitted light, or may be placed at a predetermined angle with respect to the parallel light beam from the light emitting device 18 in order to receive scattered light. Good too. In addition, two light receiving devices 20 may be arranged to receive transmitted light and scattered light. In order to simplify the explanation, the light receiving device 20 will be described below.
It is assumed that the light emitting device 18 is opposed to the light emitting device 18. Further, in FIG. 2, only one set of the light emitting device 18 and the light receiving device 20 is arranged, but the present invention is not limited to this, and a plurality of sets of the light emitting device 18 and the light receiving device 20 may be arranged. Light emitting device 18
In particular, if the light receiving device 20 is arranged on the same horizontal plane, it is convenient for detecting the sedimentation state of the aggregates, that is, the flocs 17 with high precision.

Reference numeral 22 denotes a measuring device connected to the light receiving device 20 via a lead wire 21, which measures the amount of light I received by the light receiving device 20 (hereinafter referred to as "received light amount"). In addition, the measuring device 22 calculates the received light amount I _i (τ) before the injection of the flocculant from the measured received light amount I and the stirring blade 12
Determine and output the fluctuation range (i.e., the difference between the predetermined values I _L and I _H ) ΔI and the fluctuation period F of the received light amount I when it is flattened with slow stirring,
Further, if desired, the stirring blade 12 is stopped and the amount of received light I _f (τ) is determined and output after the settling of the flocs 17 is completed. In addition, the measuring device 22 calculates the time from the start time t ₃ of the slow stirring of the stirring blade 12 to the time t ₄ when the received light amount I becomes flat, that is, the aggregate formation time T _t from the measured received light amount I. It is output to the arithmetic unit 136 (see FIG. 1).

24 has one end connected to the stirring tank 10 via an on-off valve 25.
The other end of the supply pipe is open to the supply pipe 132 (see FIG. 1). 26 is a flocculant supply pipe whose one end communicates with the flocculant supply source 28;
The other end is opened to the stirring tank 10 via an on-off valve 27. 30 is a drain pipe, one end of which is a stirring tank 10
The stirring tank 10
The detected suspension 11 is removed from the tank (see FIG. 1). 34 is a dark box that houses at least the stirring tank 10, the light emitting device 18, and the light emitting device 20;
Eliminates the effects of external light.

36 is a calculation device connected to the driving means 14 and the on-off valves 25 and 27, to which the driving means 14 gives the circumferential speed υ or the rotational speed n of the stirring blade 12, and the on-off valves 25 and 27 give the suspension liquid. supply amount M
and the supply amount N of flocculant are given, and the velocity gradient G _t is calculated using this information.
That is, the calculation device 36 calculates the volume of the stirring tank 10 (here M+N), the viscosity coefficient μ and specific gravity η of the suspension, the drag coefficient C, the area a and the circumferential speed υ of the stirring blade 12 (that is, the rotation speed n). Using the velocity gradient
G _t is calculated as G _t =[Cηaυ ³ /2μ(M+N)] ^1/2 , and this is output to the arithmetic unit 136 (see FIG. 1).

In addition, with reference to FIGS. 2 and 3, the operation of the detection device 130 will be described in detail.

After opening the on-off valve 32 and removing the suspension 11 remaining in the stirring tank 10 through the drain pipe 30, the on-off valve 32 is closed.

The on-off valve 25 is opened for a predetermined period of time, and the supply pipe 24 is opened.
A predetermined amount M (for example, 1) of the suspension is supplied into the stirring tank 10 from a suspension supply source (not shown) through the suspension.

When the supply of the suspension into the stirring tank 10 is completed,
At time t ₁ the drive means, e.g. electric motor 14
As a result, the stirring blade 12 begins to rotate rapidly, that is, at a high speed.

Thereafter, by opening the on-off valve 27 for a predetermined time at time _t2 , a predetermined amount N of flocculant is released.
The flocculant is injected from the flocculant supply source 28 into the stirring tank 10 via the flocculant supply pipe 26 . As a flocculant,
Known flocculants such as polyaluminum chloride may be used if desired. Here, N is appropriately set so that, for example, N/(M+N) becomes the injection rate W _A1 of the flocculant by the flocculant supply device 144.

Prior to the start of rapid rotation of the stirring blade 12, the light emitting device 18, the light receiving device 20, and the measuring device 22 are started, and the amount of received light I of the transmitted light is measured through the suspension in the stirring tank 10. There is.

The amount of received light I until time t ₂ , that is, the time when the flocculant is supplied, is a constant value I _i (τ) corresponding to the initial concentration W _SS of suspended matter contained in the suspension. When a predetermined amount N of flocculant is injected at time _t2 , aggregates, that is, flocs 17 are gradually formed within the suspension 11, and the suspension 11 is rapidly stirred and moved within the stirring tank 10. Therefore, the amount of light received by the light receiving device 20 increases slowly.

At time _t3 , when the stirring blade 12 starts to rotate slowly, that is, at a low speed, the suspension 11
Agglomerates or flocs 17 are formed in the stirring tank 1, and the diameter d of the flocs gradually increases, and the suspension 11 flows into the stirring tank 1.
Since the amount of light I received by the light receiving device 20 increases and decreases little by little, it increases overall.

When time t ₄ is reached, the flocs 17 are sufficiently agglomerated in the suspension 11 and their diameter d does not change, and the suspension 11 is being stirred and moved slowly in the stirring tank 10. Therefore, the amount of light I received by the light receiving device 20 is flattened, and the aggregate, that is, the floc 1
7, the predetermined values I _L and I _H begin to fluctuate periodically. The fluctuation period at this time is
It is shown in FIG. 3 as F.

Furthermore, at time _t5 , when the rotation of the stirring blade 12 is stopped to stop the slow stirring, the aggregates formed in the suspension 11, that is, the flocs 17 start to settle, so that the amount of light received by the light receiving device 20 decreases. I increases and decreases little by little, but remains almost constant at time t ₆
I _f (τ) is reached. After time _t6 , the flocs 17 in the suspension 11 no longer settle, so the amount of received light I maintains a constant value I _f (τ).

For example, when a kaolin suspension prepared by adding 25 mg of kaolin to fresh water in step 1 is used, and polyaluminum chloride is injected at an injection rate of 15 mg, the amount of light received by the light receiving device 20 is measured by the measuring device 22. , as shown in Figure 3.

The measuring device 22 determines the stirring blade 12 based on the amount of light received by the light receiving device 22, that is, the amount of received light I.
Measure the time from the start time _t3 of slow stirring to the time _t4 when flattening (i.e., the time when the formation of aggregates 17 is completed), and calculate the aggregate formation time T _t
(first
(see figure).

Further, the calculation device 36 calculates the velocity gradient G _t of the suspension 11 as described above, and calculates the velocity gradient G t of the suspension 11 as described above.
36 (see Figure 1).

In the above, the velocity gradient G _t and the aggregate formation time T _t
is simply detected by the detection device 130, but if this is optimized as follows, stirring control of the aggregate formation pond 112 can be made more efficient.

That is, the arithmetic unit 36 is also connected to the measuring device 22 and the on-off _valves 25 and 27 as shown in FIG. Necessary information such as the period F, the supply amount M of the suspension liquid, and the supply amount N of the flocculant is given. This causes the arithmetic unit 36 to calculate parameters useful in determining the state of formation of aggregates or flocs 17.

In other words, the arithmetic unit 36 calculates the diameter d (cm) of the aggregate, that is, the floc 17, as d=αΔI using the fluctuation width ΔI (volt) of the received light amount I and the constant α, and calculates the fluctuation period of the received light amount I. F (seconds) and the circumferential speed υ (m/second) or rotational speed n of the stirring blade 12
(1/sec) and the constants β and β', the number of aggregates or flocs 17 N _b (1/cm ³ ) is expressed as N _b = β (1/Fυ) ³ = β' (1/Fn) ³ Calculate the diameter d of the aggregate or floc 17
(cm), the number N _b (1/cm ³ ), and the constant ε to calculate the volume V (cm ³ ) of the aggregate, that is, the floc 17, as V=εd ³ N _b , and the amount of received light I _i (τ) Initial concentration of suspended solids in suspension W _SS (mg/) determined from (volts) and injection rate of flocculant W _A1 (mg/) determined from supply amount M and N
_The effective density ρ ⁽ g/cm ³ ) is calculated as ρ=γ1/d ³ N _b (W _SS +aW _A1 ), and if desired, the settling velocity S (cm /min) as S=δ1/T, and using the received light intensity I _f (τ) and the constant λ, the supernatant water turbidity τ (degrees) after the flocs 17 have settled is calculated as τ=λI _f (τ) is calculated. Here, the relationship between the parameters calculated by the calculation device 36 and the actual state of flocculation of the flocs 17 is as follows: diameter d or number N _b , volume V, effective density ρ, sedimentation rate S, and supernatant water turbidity τ. Therefore, if it is desired to accurately detect the agglomeration state of the flocs 17, the latter parameter may be used, and if it is desired to detect the aggregation state even more precisely. If so, you can use a combination of multiple parameters. Incidentally, the calculation device 36 may be configured not to calculate parameters that are not used.

Furthermore, the calculation device 36 calculates, as desired, the diameter d, number N _b , volume V, effective density ρ, sedimentation velocity S, and supernatant water turbidity τ after the flocs 17 have settled. At least one is stored in sequence for the speed gradient G _t at that time, and an appropriate value of the speed gradient G _t (that is, an appropriate speed gradient) G _t ^* is calculated. That is, _the arithmetic unit 36 calculates the diameter d, volume V, number
N _b , the velocity gradient G _t is determined as the appropriate velocity gradient G _t ^* in response to when the change in the effective density ρ or the sedimentation velocity S begins to become steep, or when the change in the supernatant water turbidity τ approaches a minimum. , this is processed by the arithmetic unit 136
(See FIG. 1 and FIGS. 4 to 6). In addition, the calculation device 36 determines the aggregate formation time T _t corresponding to the appropriate velocity gradient G _t ^* as the appropriate aggregate formation time T _{t *} out of the aggregate formation time ^T t calculated from the amount of received light I. Arithmetic device 13
6 (see FIG. 1 and FIGS. 4 to 6).

If this appropriate velocity gradient G _t ^* and appropriate aggregate formation time T _t ^* are used as the above-mentioned velocity gradient G _t and aggregate formation time T _t , respectively, the stirring control of the aggregate formation pond 112 can be made more efficient. .

In FIG. 2, the speed gradient G _t is directly calculated from the circumferential speed υ of the stirring blade 12 in the arithmetic unit 36, but here, υ=1/F [β/N _b ] ^1/3 is calculated as the circumferential speed. The velocity gradient G _t may be calculated by using it as υ.

In FIG. 4, a detection device 130 including only one stirring tank 10 was explained, but this requires a large amount of time to detect the state of agglomeration, and as a result, the appropriate velocity gradient G _t ^* and the appropriate time for forming aggregates are required. Since it takes time to detect T _t ^* , a plurality (four in this case) of stirring tanks may be arranged side by side as shown in FIG.

The detection device 130 in FIG. 7 has a suspension supply source (not shown) and a flocculant supply source 28 in common, a calculation device 38 and a control device 40 are added, and the function of the calculation device 36 is A part of the computing device 3
Except for the fact that it is divided into 8 parts, the configuration and operation are substantially the same as the detection device shown in FIG. The same reference numerals as those given to the detection device in FIG. 4 (as well as in FIG. 2) are given to these parts, and detailed explanation thereof will be omitted. The letters A, B, C, and D are added to the reference numbers to distinguish between the juxtaposed stirring vessels. On-off valves 25A, ~, 25D and 27
A, -, 27D are opened as appropriate so as to keep the injection rate of the flocculant to the suspensions 11A, -, 11D in the stirring tanks 10A, -, 10D constant.
The calculation device 38 is connected to the measurement devices 22A, 22D and 36A, 36D, and determines the state of aggregate formation from the velocity gradient _Gt calculated by the calculation devices 36A, 36D. The appropriate velocity gradient G _t is determined as the appropriate velocity gradient G _t ^* , and the agglomeration time corresponding to this appropriate velocity gradient G _t ^* is determined from among the aggregate formation times T _t calculated by the calculation devices 36A to 36D. The aggregate formation time T _t is determined as the appropriate aggregate formation time T _t ^* , and the appropriate velocity gradient G _t ^* and the appropriate aggregate formation time T _t ^* are sent to the calculation device 136 (see FIG. 1). . Here, the control device 40
The stirring blades 12A, . . . , 12D are rotated at mutually different rotation speeds and thus at circumferential velocities via driving means 14A, .about., 14D, respectively.

In addition, in the above description, the stirrers 113A, . . . , 1
Although the agitation control of the aggregate formation pond 112 is performed by controlling the rotational speed n _A , ~, n _C of 13C, the present invention is not limited to this.
The agitation control of the aggregate forming pond 112 may be achieved by controlling the rotation speed of the agitators 113A, 113C, the volumes of the aggregate forming basins 112A, 112C, etc.

(3) Effects of the invention As is clear from the above, the first agitation control method for the flocculate formation pond according to the present invention involves injecting the flocculant into the suspension while rapidly stirring it in the mixing basin, and then injecting the flocculant into the suspension.
In an agitation control method for an aggregate formation pond in which aggregates are formed by slow stirring in an aggregate formation pond, (a) a flocculant is injected into the suspension collected upstream of the mixing basin; The first step is to stir the mixture in the stirring tank.
(b) a second step of stirring the flocculant-injected suspension in the first step at a lower stirring speed than in the first step; and (c) in the second step. (d) at least in the second step, the amount of light received by the light emitting device to the light receiving device via the suspension into which the flocculant was injected in the first step; (e) a fifth step of determining the aggregate formation time of the suspension in which the flocculant was injected in the first step from the amount of received light measured in the fourth step; (f) a sixth step of detecting the amount of suspension supplied to the mixing basin; (g) a sixth step of detecting the velocity gradient determined in the third step, the aggregate formation time determined in the fifth step, and the sixth step; a seventh step of controlling stirring in the aggregate formation pond using the supply amount of the suspension detected in the step and the volume of the aggregate formation; () visual observation by the tester; It also has the effect of eliminating the need for experience, and also has the effect of shortening the time required to control the agitation of the aggregate formation pond.

In addition, the second agitation control method of the flocculate formation pond according to the present invention is that after injecting the flocculant into the suspension while stirring rapidly in the mixing basin, the flocculant is injected into the suspension and then slowly stirred in the flocculation basin. In a method for controlling agitation of an agglomerate formation pond formed by forming an agglomerate, (a) a first step of injecting a flocculant into the suspension collected upstream of the mixing pond and stirring it in a stirring tank; (b) a second step of stirring the suspension into which the flocculant has been injected in the first step at a lower stirring speed than in the first step; and (c) stirring the agitation in the second step. a third step of determining the velocity gradient; and (d) at least in the second step, measuring the amount of light received from the light emitting device to the light receiving device through the suspension into which the flocculant was injected in the first step. (e) From the amount of received light measured in the fourth step,
(f) detecting the aggregation state of the suspension in which the flocculant was injected in the step; (f) detecting the aggregation state detected in the fifth step from among the velocity gradients determined in the third step (g) determining the velocity gradient that makes the state appropriate as the proper velocity gradient; (h) an eighth step of detecting the amount of suspension supplied to the mixing pond; (i) a sixth step; Using the appropriate velocity gradient determined in the step, the appropriate aggregate formation time determined in the seventh step, the supply amount of the suspension detected in the eighth step, and the volume of the aggregate formation pond. and a ninth step of controlling the agitation in the agglomerate formation pond, so that in addition to the effects of () and () above, the agitation control in the agglomerate formation pond can be controlled with high precision.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an actual suspension processing apparatus in which agitation control of an agglomerate formation pond is executed by an embodiment of the agitation control method for an agglomerate formation pond according to the present invention, and FIG. is the velocity gradient G _t and the aggregate formation time T _t for carrying out an embodiment of the present invention.
FIG. 3 is an operation explanatory diagram for explaining the operation of the detection device shown in FIG. 2, and FIG. 4 is a cross-sectional view specifically showing an example of the detection device shown in FIG. An example of the detection device of FIG. 1 for detecting the appropriate velocity gradient G _t ^* and the appropriate aggregate formation time T _t ^* in order to carry out an embodiment of another agitation control method for an aggregate formation pond is specifically shown. 5 is a graph showing the relationship between the diameter d, number N _b , volume V and effective density ρ of the aggregate detected by the detection device in FIG. 4, and the velocity gradient G _t , and FIG. A graph showing the relationship between the supernatant water turbidity τ, the settling velocity S of aggregates, the effective density ρ, and the velocity gradient G _t detected by the detection device shown in Fig. 4. It is a sectional view showing four sensing devices arranged side by side. 102...Water landing well, 106...Mixing pond, 112
... Aggregate formation pond, 118 ... Sedimentation pond, 120...
... Passing pond, 130 ... Detection device, 136 ... Computation device, 138 ... Flow meter, 140 ... Rotation speed controller, 144 ... Coagulant supply device, 10 ... Stirring tank, 11 ... Suspension liquid , 12... stirring blade, 14...
... Drive means, 16 ... Output shaft, 18 ... Light emitting device, 20 ... Light receiving device, 22 ... Measuring device, 24
... Supply pipe, 25, 27 ... On-off valve, 26 ... Coagulant supply pipe, 28 ... Coagulant supply source, 30 ... Drain pipe, 32 ... On-off valve, 34 ... Dark box, 36, 3
8... Arithmetic device, 40... Control device.

Claims (1)

[Claims] 1. A flocculant forming pond in which a flocculant is injected into a suspension while being rapidly stirred in a mixing basin, and then a flocculant is formed by slow stirring in a flocculating basin. In the stirring control method, (a) a first step of injecting a flocculant into the suspension collected upstream of the mixing pond and stirring it in the stirring tank;
(b) a second step of stirring the flocculant-injected suspension in the first step at a lower stirring speed than in the first step; and (c) in the second step. (d) at least in the second step, the amount of light received by the light emitting device to the light receiving device via the suspension into which the flocculant was injected in the first step; (e) a fifth step of determining the aggregate formation time of the suspension in which the flocculant was injected in the first step from the amount of received light measured in the fourth step; (f) a sixth step of detecting the amount of suspension supplied to the mixing basin; (g) a sixth step of detecting the velocity gradient determined in the third step, the aggregate formation time determined in the fifth step, and the sixth step; A seventh step of controlling agitation in the aggregate forming pond using the supply amount of the suspension detected in the step and the volume of the aggregate forming pond. Pond agitation control method. 2. In an agitation control method for an agglomerate formation pond, in which a flocculant is injected into a suspension while being rapidly agitated in a mixing basin, and then agglomerates are formed by slow stirring in an agglomerate formation pond. a) A first step in which a flocculant is injected into the suspension collected upstream of the mixing pond and the mixture is stirred in a stirring tank.
(b) a second step of stirring the flocculant-injected suspension in the first step at a lower stirring speed than in the first step; and (c) in the second step. (d) at least in the second step, the amount of light received by the light emitting device to the light receiving device via the suspension into which the flocculant was injected in the first step; (e) a fifth step of detecting the agglomeration state of the suspension into which the flocculant was injected in the first step from the amount of received light measured in the fourth step; f) A sixth step of determining, from among the velocity gradients determined in the third step, a velocity gradient that makes the agglomeration state detected in the fifth step appropriate as an appropriate velocity gradient; (h ) an eighth step of detecting the amount of suspension supplied to the mixing pond; (i) detecting the appropriate velocity gradient determined in the sixth step and the seventh step;
The appropriate aggregate formation time determined in the step 8 and
and a ninth step of controlling stirring in the aggregate formation pond using the supply amount of the suspension detected in the step and the volume of the aggregate formation pond. A method for controlling agitation in a formation pond. 3 () In the fifth step, the aggregation state of the suspension is detected by calculating the number of aggregates from the fluctuation period when the amount of received light is flattened and the stirring speed in the second step, and ( ) Aggregate formation according to claim 2, characterized in that in the sixth step, a velocity gradient corresponding to when the change in the number of aggregates starts to become steep is determined as an appropriate velocity gradient. Pond agitation control method. 4 () In the fifth step, the aggregation state of the suspension is detected by calculating the diameter of the aggregate from the fluctuation width when the amount of received light is flattened, and () In the sixth step, the Agitation control of an aggregate formation pond according to claim 2 or 3, characterized in that the velocity gradient corresponding to when the change in the diameter of the aggregate starts to become steep is determined as the appropriate velocity gradient. Method. 5 () In the fifth step, the number of aggregates is calculated from the fluctuation period when the amount of received light is flattened and the stirring speed in the second step, and the number of aggregates is calculated from the fluctuation range when the amount of received light is flattened. The aggregation state of the suspension is detected by calculating the diameter of the aggregates and the volume of the aggregates from the number and diameter of the aggregates, and () In the sixth step, the number of aggregates and the volume of the aggregates are calculated. 3. The agitation control method for an aggregate formation pond according to claim 2, wherein the velocity gradient corresponding to when the change in diameter and volume starts to become steep is determined as the appropriate velocity gradient. 6 () In the fifth step, the number of aggregates is calculated from the fluctuation period when the amount of received light is flattened and the stirring speed in the second step, and the number of aggregates is calculated from the fluctuation range when the amount of received light is flattened. The aggregation state of the suspension is detected by calculating the effective density of the aggregates from the number and diameter of the aggregates, the suspended solids concentration of the suspension, and the injection rate of the flocculant. , and () in the sixth step, a velocity gradient corresponding to when the change in the number and diameter of the aggregates begins to become steep and the change in effective density begins to become slow is determined as the appropriate velocity gradient. A method for controlling agitation in an aggregate formation pond according to claim 2. 7 () In the fifth step, by calculating the supernatant water turbidity after the aggregates are precipitated from the amount of light received when the amount of light received becomes flat after the stirring in the second step is stopped, A patent characterized in that the aggregation state of the suspension is detected, and () in the sixth step, the velocity gradient corresponding to when the change in supernatant water turbidity starts to become minimum is determined as the appropriate velocity gradient. A stirring control method for an aggregate formation pond according to claim 2. 8 () In the fifth step, the aggregation state of the suspension is detected by calculating the sedimentation rate of the aggregate from the time from when the stirring in the second step is stopped until the amount of received light becomes flat. death,
and () in the sixth step, a velocity gradient corresponding to when the change in sedimentation velocity of the aggregate starts to become steep is determined as the appropriate velocity gradient. A method for controlling agitation in an aggregate formation pond.