JP3053481B2 - Method for controlling slaked lime injection amount in fluorine and calcium containing wastewater treatment and fluorine removal device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a fluorine content in the wastewater containing 及 beauty calcium (herein meaning "calcium ions") (which means that the "fluorine ion" herein) fluorine The present invention relates to a wastewater treatment method for removing calcium fluoride by slaked lime and controlling the amount of slaked lime to be injected.

[0002]

2. Description of the Related Art Flue gas desulfurization wastewater (hereinafter referred to as "desulfurization wastewater") generated in a coal-fired power plant and wastewater generated in a semiconductor factory (hereinafter referred to as "hydrofluoric acid wastewater") contain fluorine. Wastewater treatment methods for removing fluorine content in such wastewater as calcium fluoride using calcium salts such as slaked lime are widely used.

[0003] However, for example, the fluorine concentration in the desulfurization wastewater in a coal-fired power plant depends on the type of coal (coal type) used for power generation, the type of flue gas desulfurization apparatus (soot separation method or soot mixing method), Furthermore, even if the type of coal is the same, it generally differs depending on the power generation load. The same applies to the hydrofluoric acid wastewater, and the fluorine concentration of the hydrofluoric acid wastewater generally differs depending on the use of hydrofluoric acid and water in the semiconductor manufacturing process.

Heretofore, in the treatment using such a fluorine-removing apparatus for the fluorine-containing wastewater, the actual amount of the chemical has been adjusted manually.

FIG. 4 is a graph showing, by way of example, a model representation of the change in the fluorine concentration of the desulfurization wastewater with the elapse of the operation time of a coal-fired power plant. The horizontal axis of this figure represents the operation time, and the vertical axis represents the fluorine concentration. As shown in FIG. 4, the fluorine concentration in the desulfurization wastewater fluctuates with the elapse of the operation time. However, conventionally, the analysis of fluorine requires time and labor, and therefore, based on the expected fluorine concentration (A), In many cases, the fluorine removing device was operated while slaked lime was injected at a constant injection rate.

[0006]

In this case, the actual fluorine concentration in the wastewater is lower than the expected fluorine concentration (A) (C).
If [the peak of the concentration fluctuation is below], the slaked lime will be excessively injected, and the injection amount of sodium carbonate will be increased accordingly, leading to an increase in running cost. vice versa,
Actual fluorine concentration is higher than expected fluorine concentration (A) (B)
If the peak of the concentration fluctuation is up, the amount of slaked lime will be insufficient, the efficiency of fluorine removal will be reduced, the quality of treated water will be deteriorated, and the discharge standard water quality will not be satisfied.
Conventionally, such inconveniences have been frequently observed.

[0007] It has also been clarified that calcium (calcium ion) is present in the desulfurization wastewater, and this calcium can be effectively used for removing fluorine. However, the calcium concentration in the desulfurization wastewater also generally differs depending on the operating conditions of the flue gas desulfurization unit, the type of coal used, and the like.

For this reason, when the calcium content in the desulfurization wastewater is effectively used for removing fluorine, a certain standard concentration of calcium contained in the desulfurization wastewater (generally, a planned value) is assumed, and the amount of the slaked lime to be injected is determined. It is common to set. In this method, as in the case described above, excess and deficiency of slaked lime occurs, and there have been problems such as an increase in operating costs and an inability to stabilize the quality of treated water.

Moreover, in the above case, the calcium concentration in the desulfurization wastewater does not always fluctuate in synchronism with the fluorine concentration, and often fluctuates with little correlation. Therefore,
The desulfurization wastewater treatment equipment requires different operation management from the conventional integrated wastewater treatment equipment, for example, the measurement of only the fluorine concentration in the wastewater cannot determine an appropriate amount of slaked lime.

[0010] In order to stabilize the quality of treated water, excessive injection of slaked lime is inevitable, resulting in an increase in cost due to an increase in slaked lime consumption and an increase in waste sludge (calcium fluoride, calcium carbonate, calcium sulfate, etc.). This has caused a problem of industrial waste disposal. In addition, in order to absorb fluctuations in the concentration of fluorine and calcium in the inflow wastewater and to make the properties of the inflow wastewater as uniform as possible, it was necessary to provide a storage tank having a sufficiently large capacity and a homogenization facility therefor in the preceding stage.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to solve the above-mentioned problems, and the main object of the present invention is to minimize the amount of slaked lime injection in the fluorine removal treatment of waste water containing fluorine and calcium . Furthermore, it is intended to stabilize the quality of the treated water.

[0012] In accordance of the problems solved, fluctuations in the wastewater flow entering into the fluorine content removing device, control of hydrated lime injection amount corresponding to the variation of calcium concentration variation及beauty influx wastewater of fluorine concentration in the influent wastewater Inventing means, devising means for minimizing the required amount of slaked lime so as not to be excessive, and further, various binding ions (sulfate ion, phosphate ion) with fluoride ion and calcium ion of wastewater , Silicate ions, etc .: The concentration of various types of binding ions that react with these calcium ions in wastewater also differs depending on the type of coal, etc.). However, in order for wastewater treatment to go through at least the process of reaction → pH adjustment → sedimentation separation, a means to solve the problem that the control time constant is extremely large is devised. Rukoto was necessary.

[0013]

Means for Solving the Problems The present inventors have made intensive studies from such a viewpoint, and as a result, have completed the present invention.

[0014]

[0015]

According to the present invention, a wastewater flow rate detector for detecting the flow rate of inflow wastewater, a wastewater fluorine concentration analyzer for detecting the fluorine concentration of inflow wastewater, and a wastewater calcium concentration analyzer for detecting the calcium concentration of inflow wastewater In a control method of a fluorine content removing apparatus for removing fluorine content from a fluorine and calcium-containing wastewater provided with: a calcium concentration required for fluorine removal by a fluorine concentration signal from the wastewater fluorine concentration analyzer. Or by a multiplication coefficient, subtract the calcium concentration signal from the wastewater calcium concentration analyzer from the calculated necessary calcium concentration, and further calculate the slaked lime injection amount by an arithmetic circuit that multiplies the inflow wastewater flow rate signal from the wastewater flow rate detector. A method for controlling the slaked lime injection amount in the treatment of wastewater containing fluorine and calcium, which is calculated and output, is provided.

In this method for controlling the amount of slaked lime in the treatment of wastewater containing fluorine and calcium, the target fluorine concentration value of the treated water is set to a non-zero positive value within the allowable limit of drainage, and the target fluorine concentration value and the treated water A calculation circuit for calculating a multiplication coefficient for correcting the calculation output of the slaked lime injection amount based on the polarity of the deviation from the measured fluorine concentration value and the magnitude thereof is provided. Each time the comparison circuit determines that the effective retention volume value of the fluorine removal device has reached the fluorine concentration detection position of water, the correction multiplication coefficient is calculated and corrected, and the integrated value is reset. It is preferable to control the slaked lime injection amount by using a value obtained by multiplying the slaked lime injection amount by the correction multiplication coefficient as a remote setting value of the slaked lime injection amount controller. .

Furthermore, according to the present invention, there is provided a fluorine removing device including a primary treatment device and a secondary treatment device having a reaction tank for injecting slaked lime, wherein an inflow wastewater flow rate detector and an upstream wastewater flow detector are arranged upstream of the reaction tank. in comprising a waste water fluorine concentration analyzer and wastewater calcium concentration analyzer, comprising accordance treated water fluorine concentration analyzer to a required downstream of the secondary treatment device or between the primary processor the secondary processor cage, an arithmetic means for performing control in accordance with any of the state-like control method of slaked lime injection quantity of the present invention described above, further, injecting slaked lime according to the calculation result by the calculating means to the reaction vessel Is provided with a slaked lime injection means for performing the removal.

Hereinafter, the present invention will be described specifically and in detail. The explanation will focus on the case of desulfurization wastewater.
This is because, in the case of hydrofluoric acid wastewater, it is common that the wastewater does not contain calcium.
The same is true when is contained .

First, the fluorine concentration (F) of the wastewater flowing into the fluorine removal device is measured, and the calcium concentration required for fluorine removal (that is, the amount of calcium, which is tentatively referred to as “total calcium amount”) is measured in the actual machine. The calculation formula [F
By (x)] or simple multiplier coefficient (alpha), is calculated in accordance with the fluorine concentration, the calcium concentration in the further flow into the waste water (Ca ', which assumed as "calcium-containing amount") is measured, This value is subtracted from the total calcium amount to calculate the “deficient calcium amount” to be injected, and the “deficient calcium amount” is further converted to slaked lime amount.

Since the amount of inflow wastewater also fluctuates, the inflow wastewater flow signal (Q) obtained by the wastewater flow detector is added to the amount of slaked lime.
To calculate the slaked lime injection amount for the inflow wastewater at that time, thereby controlling the slaked lime injection amount.

The slaked lime injection amount is preferably controlled by multiplying the slaked lime injection amount by a coefficient (β) for feedback correction as an injection result, and using the obtained value as a remote setting value of the slaked lime injection flow rate controller. I do.

Further, in order to prevent excessive injection of slaked lime, the target fluorine concentration (f) of the treated water is set to an allowable non-zero positive value, and the target fluorine concentration (f ') is compared with the measured fluorine concentration (F') of the treated water. It is preferable that the multiplication coefficient (β) is feedback-corrected according to the magnitude of the deviation (F′−f) and the polarity (±).

However, as described above, the wastewater into which slaked lime is injected not only requires a considerable time delay before flowing out as treated water, but this time delay varies greatly depending on the flow rate of the inflowing wastewater. Instead of using the normal feedback control to ensure the feedback corresponding to the past control time, instead of using the normal feedback control, the effective retention volume (Q _s ) in the fluorine removing device system up to the fluorine concentration detection position of the treated water is determined. Every time the integrated value (Q _T ) of the inflow wastewater amount reaches the effective retention volume (Q _s ), a multiplication coefficient (β)
Is preferably calculated.
Note that the effective retention volume refers to the actual passage of the treated water (the primary treated water and the secondary treated water in the following embodiments) up to the fluorine concentration detection position in the fluorine content removing device. The volume of the part.

In summary, the slaked lime injection amount (Ca) is calculated according to one of the following equations. In addition,
In the following equation, K represents a constant peculiar to the apparatus, and γ represents the concentration (or density) of the slaked lime slurry actually injected.

[0026]

[Detailed expression] Ca = K · [F (x) −Ca ′] · Q · β · 1 / γ

[0027]

[Simplified formula] Ca = K · [F · α−Ca ′] · Q · β · 1 / γ

[0028]

According to the method for controlling the slaked lime injection amount of the fluorine removing apparatus configured as described above, the fluctuation of the fluorine concentration and the calcium concentration and the fluctuation of the flow rate of the wastewater due to the fluctuation of the power generation load of the desulfurization wastewater are measured by an actual machine. The obtained exact formula [F
(X)] and the multiplication coefficient (α), the optimum amount of slaked lime can be immediately and automatically injected. Therefore, in a medium-load coal-fired power plant with large load fluctuations, a large amount of slaked lime You can save money.

Further, the control by the slaked lime injection amount correction mechanism based on the fluorine concentration of the treated water can be effectively applied to the fluctuation of the composition ratio of the wastewater due to the change of the coal type and the change of the blend ratio of the coal type. As it is possible, the operator does not need to inject too much slaked lime in order to ensure the treated water quality on the safe side as before, and the operator changes the slaked lime injection amount every time according to the fluctuation of the power generation load. There is no need.

The above-described functions and the accompanying effects are the same when not only the desulfurization wastewater but also the hydrofluoric acid wastewater contains calcium .

[0031]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in more detail by way of embodiments with reference to the drawings, but the present invention is not limited to the embodiments.

FIG. 1 is a flowchart showing each processing step and a signal system in an example of a wastewater treatment apparatus which is a fluorine removal apparatus used in the present invention.

This device is a desulfurization wastewater treatment device,
In FIG. 1, the left side from the position where the primary treatment water 16 flows out is a primary treatment unit, and the right side is a secondary treatment unit (softening unit).
It is.

This primary treatment apparatus includes a reaction tank 5 (injected slaked lime), a pH adjustment tank 6 (injected caustic soda, p.
It has an H value of about 6 to about 8, a first flocculation tank 7 (for example, using an anionic polymer flocculant as an auxiliary agent), a first precipitation tank 15, and as ancillary equipment, a slaked lime dissolution tank 12,
Slaked lime injection pump 13, slaked lime injection control valve 9,
A pH adjusting agent injection valve 18 and a pH adjusting agent storage tank (not shown) are provided. The first sedimentation tank 15 is provided with a sludge extraction pump 17, and the pH adjustment tank 6 is provided with a pH detector 19.

The secondary treatment apparatus includes a softening tank 31 (for example, injecting sodium carbonate and caustic soda), a second flocculation tank 32 (for example, using an anionic polymer flocculant as an auxiliary), and a second precipitation tank 33. Have. In the softening tank 31, a pH detector 36 is provided.
The second settling tank 33 is provided with a sludge pulling pump 3
5 are provided.

The desulfurization wastewater generally contains a magnesium component (magnesium ion).
To sodium carbonate and inject caustic soda to pH
If the pH is adjusted to exceed 10 (eg, about 10.5), a precipitate of magnesium hydroxide will form, but a significant portion of the fluorine remaining in the primary effluent will probably be absorbed at the same time. Precipitation (co-precipitation), and therefore, the fluorine concentration in the secondary treatment water is further reduced.

In the above-described fluorine removing apparatus, an automatic analyzer 3 for measuring the fluorine ion concentration of the inflowing waste water 2 continuously or at short intervals (for example, utilizing the ion electrode method, Japanese Patent Application Laid-Open No. 3-51754). The fluorine concentration F of the wastewater is measured according to the publication, and a signal of this F is input to, for example, a computer 100 as arithmetic means, and the required total calcium amount is calculated by the CPU of the computer according to the following equation.

[0038]

F (x) = a · logF ² + b · logF + C [where a, b, and C are constants]

However, since this calculation is complicated, it is convenient to use the following coefficient α. The coefficient α is obtained from the results of actual equipment and various field tests, and can be used easily. The required total calcium amount can be obtained as F × α. Here, α is stored in the memory unit of the computer 100, and its value is in the range of 2.5 to 5.0.

A waste water calcium concentration automatic analyzer 4 for measuring the concentration of calcium ions contained in the inflow waste water 2 continuously or at short time intervals (for example, using a light-emitting plasma method;
-118856, 2-118857, 2-1885
8, 2-120057), the calcium content Ca ′ is measured, a signal of the Ca ′ is input to the computer 100, and [(F (x) −Ca ′]) is input by the CPU.
Alternatively, [F · α-Ca ′] is subtracted, and the calcium concentration to be increased by injection is calculated.

This value is multiplied by an instantaneous flow rate signal Q from a flow rate detector 1 for detecting the flow rate of the inflow wastewater 2 by a CPU, and the measured values of various instruments such as analytical instruments and measuring instruments used in the present apparatus are measured. Device-specific constant K determined by range, control range and unit of use (stored in memory)
And the instantaneous slaked lime injection amount when the slaked lime concentration is 100% is calculated.

Further, the concentration signal γ of the slaked lime concentration detector 11 for measuring the actual slaked lime slurry concentration is input to the computer 100 and the instantaneous slaked lime injection amount when the slaked lime concentration is set to 100% by the CPU is 1 / γ. , The slaked lime injection flow rate at the actual liquid concentration is calculated.

When an automatic melting facility capable of constantly controlling the concentration of slaked lime is prepared, 1 / γ is included in the internal constant of the arithmetic unit, and the slaked lime concentration detector 11 can be omitted.

Next, a preferred embodiment using the injection amount correction multiplication coefficient β in the above formulas (Equation 1) or (Equation 2) will be described with reference to, for example, a flowchart showing a program processing procedure in FIG. I have.

Β is expressed by the following equation.

[0046]

## EQU4 ## β = 1 + RV _(tn-1) +. DELTA.RV _(tn) [where, .DELTA.RV _(tn) = k (F'-f) _(tn) . ]

In this equation, the deviation (F ') between the fluorine concentration signal F' from the primary treatment water fluorine concentration analyzer 14 for measuring the fluorine ion concentration of the primary treatment water 16 and the fluorine concentration target value f of the primary treatment water 16 is obtained. −f) is ΔRV _(tn) =
k (F'-f) _(tn) . k is a proportional coefficient for each correction value. The cumulative value of the correction values up to the previous time is R
V _(tn-1) .

While the formulas (1) and (2) are always calculated, the formula (4) is that the integrated value Q _T of the inflowing wastewater amount is the effective accumulated volume Q _S (in this case, FIG. Is calculated every time the amount reaches the position of the fluorine concentration analyzer 14). In other words, the coefficient β is modified to a new value when it becomes a Q _T ≧ Q _S, is fixed until the next time. Further, the reset to zero inflow wastewater amount integrated value Q _T at the same time, restarts the integration.

Next, a program processing procedure performed by the computer 100 will be described with reference to the flowchart of FIG. At some point, when it is detected that the apparatus is in operation [Step (1)], the integrated value of the inflowing wastewater amount up to the previous cycle by the integrating circuit is used by the fluorine removing apparatus to reach the fluorine concentration detecting position of the treated water. The comparison circuit determines whether or not the value of the effective retention volume has been reached [step (2)]. If the value has not yet reached, the same stored β value as in the previous cycle is used, and "expression 2"
The calculation of the expression ("Equation 1") is performed by an arithmetic circuit [step (3)], and based on the result, slaked lime is formed in the reaction tank 5
Is injected into. Next, the current inflow wastewater flow rate is added to the same integrated value up to the previous time (step (4)).

[0050] repeat such a cycle, if it decided to satisfy the conditions of Q _T ≧ Q _S in step (2),
The calculation of Expression 4 is performed by a calculation circuit [Step (5)], and a new injection amount correction multiplication coefficient β is obtained, and this is used for the calculation of Step (3) from the next cycle. In this case, the integrated value of the inflow wastewater flow rate in the integrating circuit is reset to zero [step (6)]. From there, step by using the new "β" (2) → step (3) → step repeating the cycle of (4), If you are satisfied with the conditions of re-Q _T ≧ Q _S step (5) → step (6) And proceed. That is, the processing procedure is repeated.

In the above-described case, the feedback control is performed using the primary treated water 16 to measure the fluorine concentration for obtaining the injection amount multiplication coefficient β.
Can be controlled in exactly the same way by measuring the fluoride ion concentration of the treated water with the secondary treated water fluorine concentration analyzer 34 and feeding it back as F '. In the latter case, the effective residence volume Q _S is the effective retention volume to the position of the secondary treated water fluorine concentration analyzer 34 in the fluorine content removing device of FIG.

Further, both the primary treatment water fluorine concentration analyzer 14 and the secondary treatment water fluorine concentration analyzer 34 may be provided. In this case, for example, when the variation per unit time of the inflow wastewater flow rate and the influent wastewater fluoride ion concentration exceeds a certain value, the primary treatment water fluorine concentration signal from the primary treatment water fluorine concentration analyzer 14 is multiplied by the injection amount. The coefficient β may be used to determine the coefficient β, and in other cases, the secondary treatment water fluoride ion concentration signal from the secondary treatment water fluorine concentration analyzer 34 may be used to determine the injection amount multiplication coefficient β. In this case, since the former case has a smaller effective retention volume than the latter case, there is an advantage that it can respond to a rapid change in the inflow wastewater flow rate and the influent wastewater fluoride ion concentration in a shorter time, while When the fluctuation of the inflow wastewater flow rate and the inflow wastewater fluoride ion concentration is not so large, the advantage that the feedback control can be more precisely performed with the secondary treatment water fluoride ion concentration signal which is more closely related to the desired treatment water quality can be secured. Also, for this purpose, the treated water fluorine concentration analyzer is shared, and the sample line can be switched alternately, so that the primary treated water fluoride ion concentration and the secondary treated water fluoride ion concentration can be one treated water fluoride concentration analyzer. The measurement may be performed.

To set the treated water fluorine concentration target value f to a positive value within the allowable limit of drainage which is not zero, specifically, is set higher than the measurement limit value (lower limit) of the fluorine concentration analyzer 14 or 34, This means that the value is set to a value larger than the error value and within the allowable discharge limit, in order to perform control to avoid excessive injection of slaked lime. The reason is that f is equal to or less than the measurement limit value of the fluorine concentration analyzer 14 or 34 plus the measurement error value.
When the value is set, if F ′ becomes equal to or less than the value of the measurement limit value plus the measurement error value of the fluorine concentration analyzer 14 or 34 due to the excessive injection, it is not possible to determine whether the injection is excessive or not and the degree of the excessive injection. .

The slaked lime injection amount Ca obtained by the equation (Equation 1) or (Equation 2) thus obtained is set as a remote set value of the slaked lime injection flow controller 10 and is actually measured by the slaked lime injection flow detector 8. The injection amount is compared with and adjusted by the computer 100, and the opening command MV value (operation output value, manipulating val
ue). Note that the control valve 9 of the drive unit for controlling the injection amount is not necessarily a control valve. For example, a plunger-type metering pump may be used as the slaked lime injection pump 13 without the control valve. A combination of stroke control and rotation speed control with the metering pump may be used.

FIG. 3 shows, as examples, the fluorine concentration and calcium concentration in the desulfurization wastewater, the fluorine concentration in the primary treatment water obtained from the first precipitation tank, and the fluorine concentration in the secondary treatment water obtained from the second precipitation tank (" FIG. 7 is a graph showing temporal changes in the case of “no feedback” and the case of “with feedback” due to the fluorine concentration of the secondary treatment water). In FIG. 3, the horizontal axis represents the operation time, and the vertical axis represents the concentration. This graph is a semi-log graph, and the density scale on the vertical axis is a logarithmic scale.

In FIG. 3, curve (a) is the concentration of calcium in the wastewater, curve (b) is the concentration of fluorine in the wastewater,
Curve (c) is the fluorine concentration of the primary treated water, and curve (d)
Is the fluorine concentration of the secondary treatment water in the case of "no feedback", and the curve (e) is the fluorine concentration of the secondary treatment water in the case of "with feedback".

It can be seen that the control of "with feedback" has a smaller fluctuation range of the fluorine concentration of the secondary treatment water than the case of "without feedback", which is preferable.

In the present invention, the calculation of the formulas (1) and (2) can be performed not only by a dedicated computing unit but also by a control computer using a one-loop control which is commercially available and can perform the above calculations.
It can be used as a controller, or as an arithmetic circuit for a personal computer or sequencer.

[0059] In the above embodiment, although the invention has been described desulfurization waste water as an example, the same for hydrofluoric acid wastewater containing calcium.

[0060]

As described above, according to the present invention, an appropriate amount of slaked lime can be injected almost in real time with respect to fluctuations in the properties of waste water containing fluorine and calcium and fluctuations in the flow rate of waste water. A semiconductor that performs a process in which the amount of hydrofluoric acid used fluctuates significantly depending on the desulfurization wastewater and the time of day, especially in intermediate-load coal-fired thermal power plants with large load fluctuations, because it can prevent excessive injection of slaked lime with a subtle correction correction mechanism The use of slaked lime and other chemicals in factory hydrofluoric acid wastewater can be greatly reduced.

Further, the amount of calcium carbonate and the like as waste is reduced, and the sludge treatment equipment can be reduced.
It also helps to reduce the problem of industrial waste.

Automatic follow-up to fluctuations in the flow rate and properties of inflow wastewater is remarkably improved as compared with the related art, so that the burden on operators is reduced.

[Brief description of the drawings]

FIG. 1 is a flowchart showing each processing step and a signal system in an example of a wastewater treatment apparatus including a fluorine content removing apparatus used in the present invention.

FIG. 2 is a flowchart showing a program processing procedure of a control system based on an injection amount correction multiplication coefficient β.

FIG. 3 is a diagram for explaining the wastewater treatment effect when the control method according to the present invention is used, and shows the fluorine concentration and the calcium concentration in the desulfurization wastewater, the fluorine concentration in the primary treatment water obtained from the first precipitation tank,
FIG. 7 is a graph showing a temporal change in the fluorine concentration of the secondary treatment water obtained from the second precipitation tank (without feedback and with feedback).

FIG. 4 is a graph schematically showing a change in the fluorine concentration of the desulfurization wastewater with the elapse of the operation time of the coal-fired power plant.

[Explanation of symbols]

 Reference Signs List 1 wastewater flow detector 2 inflow wastewater 3 wastewater fluorine concentration analyzer 4 wastewater calcium concentration analyzer 5 reaction tank 6 pH adjustment tank 7 first flocculation tank 8 slaked lime flow detector 9 slaked lime injection control valve 10 slaked lime injection controller 11 slaked lime concentration detection 12 Slaked lime dissolving tank 13 Slaked lime injection pump 14 Primary treated water fluorine concentration analyzer 15 First sedimentation tank 16 Primary treated water 17 Sludge extraction pump 18 pH adjusting agent injection valve 19 pH detector 31 Softening tank 32 Second flocculation tank 33 No. Secondary sedimentation tank 34 Secondary treatment water fluorine concentration analyzer 35 Sludge extraction pump 36 pH detector 37 Secondary treatment water 100 Computer

Continued on the front page (72) Inventor Mamoru Toriyao 1 at 20 Kitakanyama, Odaka-cho, Midori-ku, Nagoya-shi, Aichi Prefecture Electric Power Engineering Laboratory, Chubu Electric Power Co., Inc. (72) Inventor In the Power Technology Research Institute, Chubu Electric Power Co., Inc., 20-20 Kita-Sanzan, Odaka-cho, Midori-ku, City (72) Inventor Takada ▲ Toki ▼ 5-5-16-1 Hongo, Bunkyo-ku, Tokyo Organo Corporation ( 72) Inventor Hidetoshi Takami 5-16, Hongo, Bunkyo-ku, Tokyo Organo Co., Ltd. (56) References JP-A-60-202788 (JP, A) JP-A-58-1443878 (JP, A) Kaikai 52-24762 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) C02F 1/00-1/78

Claims (3)

(57) [Claims] 1. A wastewater flow rate detector for detecting the flow rate of inflowing wastewater, a wastewater fluorine concentration analyzer for detecting the fluorine concentration of the inflowing wastewater, and a fluorine having a wastewater calcium concentration analyzer for detecting the calcium concentration of the inflowing wastewater. And a control method of a fluorine removing device for removing fluorine from waste water containing calcium, wherein a calcium concentration necessary for removing fluorine is determined by a predetermined calculation formula or a multiplication coefficient according to a fluorine concentration signal from the waste water fluorine concentration analyzer. Calculate and subtract the calcium concentration signal from the wastewater calcium concentration analyzer from the calculated required calcium concentration, and further calculate and output the slaked lime injection amount by a calculation circuit that multiplies the inflow wastewater flow rate signal from the wastewater flow rate detector. And control method of slaked lime injection amount in treatment of wastewater containing calcium and calcium. 2. The target fluorine concentration value of the treated water is set to a positive value within the allowable limit of drainage which is not zero, and the polarity and magnitude of the deviation between the target fluorine concentration value and the measured fluorine concentration value of the treated water are set. A calculation circuit for calculating a correction multiplication coefficient for correcting the calculation output of the slaked lime injection amount, and the integrated value obtained by the integration circuit for integrating the flow rate of inflow wastewater is used to remove the fluorine content up to the fluorine concentration detection position of the treated water. Each time the comparison circuit determines that the effective retention volume value of the device has been reached, the fluorine removing device has a function of calculating and correcting the correction multiplication coefficient and resetting the integrated value, and the amount of slaked lime is added to the slaked lime injection amount. The slaked lime in the treatment of waste water containing fluorine and calcium according to claim 1, wherein the slaked lime injection amount is controlled by using a value multiplied by the correction multiplication coefficient as a remote setting value of the slaked lime injection amount controller. How to control the injection volume. 3. A fluorine content removing device including a primary processing device and a secondary processing apparatus having a reaction vessel for injecting slaked lime, waste <br/> the inlet waste water flow sensors arranged in an upstream of the reactor A water fluorine concentration analyzer and a wastewater calcium concentration analyzer are provided, and a treated water fluorine concentration analyzer is provided as required between the primary treatment device and the secondary treatment device, downstream of the secondary treatment device, or both. Computing means for performing the method for controlling the amount of slaked lime according to claim 1 or 2 ,
The apparatus for removing fluorine content further comprises slaked lime injection means for injecting slaked lime into the reaction tank according to the calculation result by the calculation means.