JPS62108147A - Water quality control meter - Google Patents

Abstract

PURPOSE:To improve the reliability of a water quality meter by monitoring the value detected with a dissolved oxygen concn. meter, etc. in a sewage treatment plant, etc., forcibly cleaning a detection part when a set value or above is attained and eliminatin the measurement error by sticking of foreign matter thereto. CONSTITUTION:A detecting electrode part 6 of the immersion type water quality meter 1 is put into a part to be measured (sewage) and a PID (proportional plus integral plug derivative action) controller is provided to a control box 4 for cleaning to detect the water quality. A detection signal b is outputted from the PID when the foreign matter sticks thereto. A delay signal c delayed for the prescribed time is also outputted. A rinse signal is quickly emitted when the output signal difference (b-c) therebetween is larger than a set value U. Cleaning water is forcibly emitted from a ringing device 2 to the electrode part 6 to remove the foreign matter. Operation is thus made by maintaining the normal process variable (PV). Since the controller having the function to detect the foreign matter and the function to correct the PV in the above- mentioned manner is provided, the reliability of the water quality controller is improved.

Description

[Detailed description of the invention] [Industrial application field] This invention can be used in sewage treatment plants, etc.

meter (dissolved oxygen concentration meter), or SS meter, MLSS meter,
The present invention relates to an immersion type water quality meter such as PH1i-, and its cleaning method and adjustment operation.

[Conventional technology]

FIG. 3 is a side view showing a conventional water cleaning device for a water quality meter. In the figure, (1) is an immersion type water quality meter, the detection electrode part of which is immersed in the liquid to be measured (for example, sewage). .

(2) is a water cleaning device, which is equipped with a nozzle that sprays water toward the detection electrode section. (3) is a pedestal that supports the water quality meter (υ), and is composed of a lifter, etc. for maintenance. (4) is a cleaning control box.

(5) is the cleaning pulp provided in the water cleaning device (2), (
6) is the part to be cleaned such as the detection electrode of the water quality meter (1), (7
) is a foreign substance that adheres to the detection electrode part. FIG. 4 is a time chart showing a conventional water cleaning operation, in which (8) is the cleaning interval time and (9) is the cleaning time. Figure 5 is a configuration diagram showing a conventional control system, where αq is the water quality meter detector, CL, ) is PID (proportional, integral, differential operation) v4, node weight Q2 is the process variable (
PV), (to) is the setting value (SV) of controller < 11, α◆
is the control output signal (MV).

Next, the operation will be explained. The immersion type water quality meter (1) is supported by a pedestal (3) comprising a lifter or the like in, for example, an aeration tank of a sewage treatment plant, and its detection electrode portion is immersed in the water to be treated. When a foreign substance (7), which is a pollutant, adheres to the detection electrode part of the water quality meter (1),
The cleaning valve (5) is opened by the signal from the timer relay built into the cleaning control box (4), and water is sprayed from the nozzle through the piping of the cleaning device (2) to clean the parts to be cleaned, such as the detection electrode. (6) to remove foreign matter (7) attached to the cleaning control box (4).As shown in the time chart in Figure 4, the cleaning control box (4) is operated by a 24-hour timer. According to the interval time 'r+(s), 6
During the cleaning time T set by a 0-minute timer, etc., open the cleaning pulp 5V (5), which is a wake-up valve, by (9) and spray water etc. from the nozzle to remove the foreign matter (7) and make a normal measurement. Restore the environment.

In addition, the water quality meter (1) has a PID as shown in Figure 5.
The % saving meter α functions as a weight detector αq, and at its output, the chilling process variable Pv(6) is input to the controller α1 and compared with the set value 5V (Ll), and the controller α1 is adjusted according to the deviation signal. ) performs PID control calculations and outputs the control signal MYα◆ to the operating end to perform predetermined control.

[Problem that the invention seeks to solve]

In the conventional water quality meter cleaning device configured as described above, cleaning was performed several times a day at preset time intervals such as a 24-hour timer, so depending on the condition of the water to be treated, , within this set time interval, foreign matter that is contaminant adheres to the detection electrode section, causing a measurement error, and the PI
In some cases, an abnormal process variable Pv was input to the D controller, and the control system was unable to perform normal control until the next cleaning time was reached, making it impossible to perform good sewage treatment. For this reason, in sewage treatment plants, etc., the reliability of water quality meters is low, and the process variables (PV) measured by water quality meters are not used as the main control variables of the control system, but are used as sub-control system or monitoring variables. Currently, it is only used as a.

This invention was developed to solve the problems of the conventional ones as described above, and when foreign matter adheres to the detection electrode part, it is quickly detected and a cleaning command is output separately from the cleaning at the normal time. Along with that.

The water quality measurement value taken shortly before an abnormality occurs is stored, and when an abnormality occurs, this memorized measurement value is output as a process variable pv, allowing the control system to continue its control operations without any hindrance. The purpose is to improve the reliability of

[Means for solving problems]

The water quality controller according to the present invention detects an abnormality in the signal of the detector caused by foreign matter adhering to the detection electrode part, based on the rate of change over time of the detected value, and when this rate of change exceeds a set value, an abnormality occurs. When detected, in addition to the normal 24-hour timer command, the detection electrode is forcibly washed with water.
This system quickly removes measurement abnormalities due to foreign matter N and the like, and maintains the process variable (PV value) at a value close to normal during the cleaning period, allowing for good adjustment operations.

[Effect]

6 with the water quality controller of this invention! , even if foreign matter adheres to the detection electrode and an abnormality occurs in the output signal from the detector, the foreign matter can be quickly removed by detecting the kneading and outputting a water washing command, and the controller's operation This can also be done in a way that does not disrupt the operation of the process.

[Embodiments of the invention]

FIG. 1 is a block diagram of a water quality controller showing an embodiment of the present invention. In the figure, α0 is a water quality meter, αη is a PI
D controller, (a) is the first process variable (PV value) detected by the water quality meter, υ is the set value, α→ is the PID controller aη
This is the control signal (MV value) outputted from the system, and the above is the same as the conventional system shown in FIG. (to) is an arithmetic circuit according to the present invention, which has a foreign matter adhesion detection function and p
It has a v value correction function. The handle is a Maruna loop controller that includes an arithmetic circuit Q5.

FIG. 2 is a detailed block diagram of the arithmetic circuit (to) according to the present invention, and in the figure, αq is the detection signal (
b) Output. Ql) is a delay circuit, and the detection signal (b)
output a delayed detection signal (c) that is delayed by a predetermined time.

(A) is a subtraction circuit, and 翺 is a comparison circuit, which compares the output signal (b-c) of the subtraction circuit (A) with the set value (UH).

(b) If C>UH, an H level signal d is output. (C) is a rate of change detection circuit that calculates ΔU/Δt.

(C) is the feed value circuit, (C) is the comparison circuit, and the set value (Δ
UH), and if ΔU/Δt≧ΔUH, an H level signal (e) is output. (Incorporated) is an AND circuit, @ is a subtraction circuit, Kan is a supply value circuit, (1) is a comparison circuit, which compares with the set value UH, and if (1(a)-(b) l)≦UH Outputs HL/bell signal (g). This is a G-cover flip-prop circuit, and is set by the hold condition signal (f) output from the AND circuit (a). 0 is a timer circuit, and its time amplifier signal (h) resets the flip-flop circuit 61). (to) is A
The ND circuit outputs a measured value return possible condition signal (i).

(b), (to), (to) are analog switches, (3'f
) is a NOT circuit.

The operation of the water quality controller configured as above will be explained. Normally, when there is no foreign matter attached to the detection electrode of the water quality meter (to), the detection signal (b) is input to the PID adjustment HIJ via analog switches (b), (2), and (g). PID control calculation is performed according to the deviation from the set value Sv (to), and a control signal MVa4 is output to each actuator. Also, this detection signal (b) +':! , delay circuit Q1), subtraction circuit (A), rate of change detection circuit (C), and subtraction circuit -, and the delay detection signal (c) is delayed by a predetermined period of time in the delay circuit (C). Subtraction of (b − c) is performed in circuit (a), and this output (
b - c) is compared with a preset setting value (UH) in the comparator circuit (a), and if (b - C)≦UH, L is reached.
Since a level signal is output, the logic of the AND circuit is not established, and the analog switches (b) and (to) are on the detection signal (b) side. The rate of change detection circuit (c) calculates the rate of change (ΔU/Δt) of the detection signal ('b), outputs it to the comparison circuit (a) via the feed value circuit (c), and outputs it to the comparison circuit (a) via the feed value circuit (c). Compare it with the set value △UH. Also, in the subtraction circuit,
Subtraction is performed with the detection signal (a) that has passed through the analog switch (c), and the signal is input to the comparison circuit (7) via the absolute value circuit, where it is compared with the set value UH.

Now, foreign matter has adhered to the detection electrode part of the water quality meter αQ, and the detection signal value (detection signal value) has changed, and the comparison circuit (2) outputs an H level signal (d) due to (b-c)>UH, and the comparison circuit The pen (
When ΔU/Δt)≧ΔUH and outputs the H level signal (e), the AND circuit outputs the water cleaning command (WS), outputs the hold signal (f), and turns on the analog switch (b). Switch to delay detection signal (e) side.

The signal (C) is held by the analog switch (c), the hold signal (a) is output, and the analog switch (2)
) to the process variable Pv(6) to the PID controller αη
This prevents the control system from being disturbed by the abnormality detection signal (b). At the same time, the hold signal (f) enters the flip-flop circuit G1), starts the timer circuit G-, and during this timer one hour, the analog switch G0
The hold signal (a) is held by.

Through the above operations, the detection electrode part of the water quality meter αq is washed with water to remove foreign matter, and when the detection signal (b) becomes stable and normal, (b − c ) ≦UH1 (△U/Δ1
) < △UH, and the output (f) of the AND circuit (goods) is L
level, and the analog switches (b) and (c) return to "a". Therefore, its feed value CI (a) - (
b) When l) is below the set value (UH), the comparator circuit (7) can output an H level signal (g), but the output (h) remains L until the time limit of timer circuit 0■ is reached.
Since it is a level, the logic of the AND circuit (to) does not hold. When the timer circuit G1 reaches the time limit and outputs the time-up signal (h), the AND circuit 01 outputs the measured value return possible condition signal (1), releases the hold by the analog switch OQ, and starts the detection from the water quality meter αq. PIDID controller α using signal (b) as direct process variable Pv(6)
and return to normal control operation. However, if the detection signal (b) does not return to normal even after the set time of timer circuit 02 has elapsed, it is assumed that the water cleaning has not been effective, and an alarm (ALAR) is sent via the NOT circuit. Output.

FIG. 6 shows the change in pv value due to the above operation.

(~ is the multi-loop controller (1) (, in the conventional control system, when foreign matter adheres to the detection electrode part of the water quality meter αq, (B) is when water cleaning is performed in the conventional example, (C ) 't''!Multi-loop controller (1
), when water cleaning is performed in the control system.
There is little disturbance in the control system and the time is short. In addition, (1
n-1 represents the time of foreign matter adhesion, (tn) represents the time of cleaning start, and (Tl represents the cleaning time).

Although the above control system has been described as a multi-loop controller, it may be configured as a loop controller. In addition, Sef f and L4 of water quality meter αq, DO
The present invention is not limited to water quality meters, S sit meters, MLSS meters, UV meters, PH meters, etc., but can be applied to all water quality meters that use a cleaning device.

Further, although the washing device (2) was explained as water washing in the above embodiment, it is not limited to kneading.

Cleaning with a chemical solution or the like may be used, and can be similarly applied.

〔Effect of the invention〕

As explained above, this invention has a foreign matter adhesion detection function and a
Since a multi-loop controller with a v value correction function is installed, when foreign matter adheres to the sensor part of a water quality meter, it can be immediately cleaned and removed, and the pv
Since abnormal fluctuations in values can be prevented, disturbances in the control system do not occur, and the reliability of the sensor of the water quality meter is improved, resulting in the effect that good control operation can be realized.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a water quality controller showing an embodiment of the present invention, FIG. 2 is a detailed block diagram of the arithmetic circuit shown in FIG. 1, and FIG. 3 is a side view showing a water cleaning device for the water quality meter. FIG. 4 is a time chart showing a conventional water washing operation, FIG. 5 is a block diagram showing a conventional control system, and FIG. 6 is a diagram showing changes in pv values according to the conventional example and the present invention. In the figure, CICJ is a water quality meter and αη is a PID controller. (G) is an arithmetic unit, (A) is a multi-loop controller, Ql) is a delay circuit, (2), @ is a subtraction circuit, (C), (1) is a comparison circuit, B is a flip-flop, (I) is a )
is a timer circuit, (b), (c), @c is an analog switch. In addition, in the figures, the same reference numerals 'tl indicate the same or equivalent parts. Agent Patent Attorney Tadashi Sato Figure 6 (A) PV PV (B) PV (C)

Claims (1)

[Claims] DO meter, SS meter, ML in sewage treatment plants, etc.
In water quality meters such as SS meters, UV meters, and PH meters, in addition to cleaning commands using a normal 24-hour timer, the rate of change in detected values is monitored, and if the rate of change exceeds a preset value, Forcibly wash the detection electrode with water,
A water quality controller characterized by quickly removing measurement errors due to adhesion of foreign substances, etc., and maintaining a process variable (PV value) at a value close to normal during the cleaning period to perform a good adjustment operation.