JPS5834192B2 - Gensuijiyoukaseigiyosouchi - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a raw water purification control device for purifying raw water in a water purification plant or the like.

In water treatment plants for waterworks that use river water as raw water, it is necessary to purify contaminated raw water until it is suitable for the intended use.

Conventionally, in order to purify raw water, floating colloidal substances are coagulated and precipitated by injecting coagulants of polyvalent metals such as aluminum sulfate or polyaluminum chloride, and the raw water is purified by sand flow etc. ing.

At this time, in order to make the raw water suitable for the purpose of use, the injection rate at which the polyvalent metal coagulant mentioned above is injected into the raw water varies depending on changes in the turbidity, alkalinity, pH value, water temperature, etc. of the raw water. Most affected by turbidity.

For example, when raw water becomes cloudy due to rain, it becomes as shown in Figure 1.

In other words, the turbidity gradually increases due to rainfall, and when the rain stops, the turbidity decreases.

At this time, the same turbidity A is taken when the turbidity rises and when it falls, but in the past, flocculant was injected at a constant injection rate without changing the injection rate when the turbidity rose and fell.

However, when the turbidity increases and when it decreases, even if the turbidity is the same, the size of the particles in the raw water is different, so the purification time etc. are different and the purification efficiency is poor at the same injection rate.

In order to eliminate this drawback, the present invention aims to improve the purification efficiency of raw water by injecting flocculant into raw water at different injection rates when the turbidity increases and decreases, thereby providing an optimized raw water purification control device. be.

In the present invention, in order to achieve this objective, the injection rate of the flocculant is changed when the turbidity increases and when the turbidity decreases even when the turbidity is the same.

In other words, as shown in Figure 2, in the turbidity vs. time curve, the injection rate when the turbidity change JTB = TB (tn) - 'I'B (tn - t) is greater than 0 and the injection rate when it is less than 0. This is done by changing the

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 3 shows an embodiment of a raw water purification control device, in which raw water is sent through a pipe 1 to a chemical mixing pond 2 and purified with a flocculant from a flocculant tank 3.

A flow rate transmitter 4 is provided in the pipe 1, and this flow rate transmitter 4
Multiplier 5 as one-manpower of multiplier 5 which multiplies two-manpower
A flow rate signal F of raw water is added to .

A piping 6 is provided to inject the flocculant from the flocculant tank 3 into the chemical mixing pond 2, and this piping 6 is provided with a flow rate transmitter 7 for detecting the flow rate of the flocculant.

In addition, raw water is sucked up from pipe 1 by pump 8,
The turbidity signal TB is sent to the turbidity detector 9 and generates a turbidity signal TB proportional to the turbidity.

This turbidity signal TB is compared with the standard turbidity, which requires changing the flocculant injection rate, ie, the turbidity TBH shown in FIG. When the output relay 11 is energized.

This reference turbidity is determined by determining the river characteristics, that is, the average turbidity when there is no normal rainfall, and providing a dead zone so that the comparator 10 cannot excite the output relay 11 due to a slight change in turbidity. It is common to take three times the value.

Further, the turbidity signal TB is applied to the comparator 12 as one-manpower of the comparator 12 that compares the two-manpower, and is also applied to the signal memory 14 via the contact 13a.

The contact 13a is opened and closed at predetermined intervals by the fixed-period sample signal generator 13, and the signal storage 14 stores the input until the next input is applied, and outputs the stored signal as the other input of the comparator 12. .

Therefore, the comparator 12 determines the difference between the current turbidity and the turbidity one cycle ago, that is, the polarity of increasing or decreasing turbidity.
An output is output when the turbidity stored in the signal storage device 14 is greater than the current turbidity, that is, when the turbidity is decreasing.

That is, they form a polarity detection circuit.

This output excites the output relay 15 via the contact 11a of the output relay 11, which closes when the reference turbidity 'l'BH<turbidity TB.

This relay 15 becomes energized when reference turbidity TBH<turbidity TB and the change in turbidity tends to decrease, and becomes de-energized when the change in turbidity tends to increase.

Furthermore, the turbidity signal TB is applied to a computing unit 16, and the injection function f ('I'B) is inputted from this computing unit 16 to a coefficient computing unit 17,
Join 18.

This injection function f(TB) is f(TB) = Ct +
C2X T or f (TB)=c3+c,X,
/ Represented by Te et al.

However, C1 to C4 are constants). The coefficient calculator 17 sets the coefficient to 1.
．． A coefficient 18 multiplies the output of the arithmetic unit 16 by 2 and is applied to the multiplier 5 as another input to the multiplier 5 via contacts 15a and 15b, respectively.

That is, the injection function f(
TB), which changes the slope of the output of the arithmetic unit.

The contacts 15a and 15b are contacts that are operated by the output relay 15 and open and close differently.

Then, the contact point 15a where the output relay 15 operates is closed, and the contact point 15b is open.

In other words, when the amount of change in turbidity is positive (turbidity rise), contact 15
When b closes and contact 15a opens, 1f (TB) is added to multiplier 5, and when the amount of change is negative (turbidity decrease), contact 15a
closes, contact 15b opens and adds 2 f (TB) to multiplier 5.

Therefore from multiplier 5 to Ktf(TB)F or to 2
f (TB)F is output, this signal is applied as a reference signal to the flow rate controller 19, and the flow rate controller 19 compares it with the flow rate signal from the flow rate transmitter 7, and an adjustment signal is sent to the electromagnetic device provided in the piping 6. added to valve 20.

Therefore, the solenoid valve 20 is controlled by different reference signals when the turbidity increases and when the turbidity decreases.

Therefore, when the turbidity of the raw water increases and exceeds the reference turbidity TBH, the output relay 11 is energized by the comparator 10 and the contact 11a is closed. The comparator 12 operates to detect an increase based on the polarity of the amount of change in turbidity.

At this time, since there is no output from the comparator 12, the contact 15b is opened, and the contact 15a remains open, so the flow rate controller 19 controls the injection amount of the flocculant using 1f (TB) F as a reference signal.

When the turbidity is decreasing, the output relay 15 is activated by the output of the comparator 12 to open the contact 15b and close the contact 15a, thereby controlling the injection amount of the flocculant using 2f(TB)F as a reference signal.

As described above, according to the present invention, the reference signal for injecting the flocculant when the turbidity rises and falls is changed by changing the coefficient by which the raw water flow rate signal is multiplied, so that optimal control can be achieved. , which increases purification efficiency.

Further, in the present invention, another coefficient may be multiplied by 3 when the reference turbidity TBH or less, and this can be implemented by multiplying various coefficients depending on the magnitude of the turbidity.

Further, the output relay and contacts may be replaced with electronic switches or the like.

Furthermore, instead of analog calculation processing, digital processing using a microcomputer or the like may be used.

[Brief explanation of drawings]

FIG. 1 is a diagram showing changes in turbidity over time, FIG. 2 is a diagram showing a turbidity function, and FIG. 3 is a block diagram of an embodiment of the present invention. 1.6... Piping, 4, 7... Flow rate transmitter, 5... Multiplier, 9... Turbidity detector, 10
, 12... Comparator, 11, 15... Output relay, 13... Fixed period sample signal generator, 14... Signal storage, 17° 18...
・Coefficient calculator, 19...Flow rate controller.

Claims (1)

[Claims] 1 In a device that purifies raw water by injecting chemicals into raw water, there is a flow rate detector that detects the flow rate of raw water, a turbidity detector that detects the turbidity of raw water, and a turbidity signal from this turbidity detector. a polarity detection circuit that calculates the polarity of the amount of change in turbidity; a comparator that compares the turbidity signal with a reference turbidity signal; a circuit for calculating, a circuit for outputting a coefficient selected by the output of the polarity detection circuit when the turbidity signal becomes equal to or higher than the reference turbidity signal by the comparator, and a coefficient selected for the output of the flow rate detector. a coefficient circuit that outputs a signal multiplied by a coefficient, and a controller that adjusts the injection of the drug into the raw water using the output of the coefficient circuit as a reference signal, and multiplies the signal depending on when the turbidity increases or decreases. A raw water purification control device characterized by changing the coefficient.