JPS60179196A - Device for controlling aeration blower in waste water treating equipment - Google Patents

Abstract

PURPOSE:To reduce the power to be needed, and to stabilize biological treatment by providing an airflow controller for determining the necessary amt. of aeration air on the basis of the control deviation from the desired DO value, a number controller for determining the number of aeration blowers to be needed, and an inverter, etc. CONSTITUTION:When the manipulated variable of an inverter reaches the upper limit value and specified hours elapse, the capacity of a blower in operation is deficient. Consequently, one constant airflow type blower is additionally started by a relay control panel 30 on the basis of the output signal of an airflow controller 28. The manipulated variable of the airflow controller 28 is elevated to the upper limit by the signal of completion of starting from the relay controller 30, and the manipulated variable of the inverter rises to the upper limit. When the DO value is regulated within the limits of gap, the manipulated variable is naintained constant, and the airflow for aeration is fixed.

Description

[Detailed Description of the Invention] Industrial Application Field This invention relates to a device for controlling the amount of aeration in an aeration tank when treating wastewater with TIs such as domestic wastewater by an activated sludge method. , can be used in the field of wastewater treatment or pollution prevention.

As is well known in the prior art, the activated sludge method is a method in which pollutants in wastewater are oxidized and decomposed by activated sludge, and then the activated sludge is separated by sedimentation, and a clean supernatant is discharged. In other words, in this method, sludge consumes oxygen dissolved in wastewater to decompose pollutants, so the amount of pollutants in wastewater (BOD concentration) and the activity of sludge based on the amount of wastewater or temperature etc. It is necessary to supply a corresponding amount of oxygen into the wastewater. This supply of oxygen is done by aeration, which blows air into the waste water using a blower, but -1! When li is small, the waste water cannot be purified sufficiently, and on the other hand, when the amount of aeration air is too large, the driving energy of the aeration blower is unnecessarily consumed.

Therefore, conventionally, the DO value (dissolved oxygen amount) in the aeration tank
But BOD+! ! The aeration air volume is controlled to a predetermined value (set value) depending on the temperature, etc. FIG. 1 is a schematic diagram 1' showing an example of a conventional device for this purpose. Inside the aeration tank 1, there is a DO meter 3 that measures the DO value of the waste water 2 and outputs it as an electric signal, and a pile of activated sludge. An MLSS meter 4 that measures and outputs it as an electric signal and an aeration diffuser 5 are arranged, and the DO meter 3 and the MLSS meter 4 are connected to a micro combi coater 7 via a Δ-D converter 6, and an aeration diffuser. The device 5 is attached to an air main pipe 10 that communicates with a color variable blower 8 and a plurality of (two in the figure) constant air volume blowers 9. In addition, a flow meter 12 is provided in the wastewater inflow pipe 11, and its 1tHt12 is connected to the microcombi 1-tough via the output horn 13 that outputs the detected value as an M signal and the A-D converter 6. has been done. Furthermore, the PAA phase variable blower 8 changes the output signal of the microcomputer 7 to D-Δ19! Inverter 15 via converter 14
It is controlled by a frequency conversion method based on the output signal, and each constant 1! II
The mold blower 9 is controlled to be turned on and off by the microcomputer 7. In the device shown in Zunarichi Figure 1, the detected values from the Do meter 3, the MLSS meter 4, and the flow B meter 12 are processed by the microcomputer 7 according to a preset program, and the amount of ffl is varied according to the values. By controlling the amount of air blown by the variable blower 8 and the number of units driven by the constant air amount blower 9, the DO in the aeration 11 is controlled.
'Control the value to bring it closer to the set value.

However, in the above device, by using the microcomputer 7, various types of data are used to determine the aeration level.
! Although it is possible to control lff1, not all data necessarily function effectively in controlling cold air mm, which causes the following problems. In other words, the conventional device described above performs feedforward control by detecting the amount of inflow of wastewater, but although the amount of inflow increases during rainy weather, the DO efficiency is not low, and conversely, when concentrated wastewater flows in, the amount of inflow Although there is no particular increase in DO! ! ! In this way, there is often no correlation between the amount of inflow of wastewater and the DO value. Also, it is desirable to increase the aeration I'll in proportion to the amount of activated sludge, but the output signal of the current MLSS total 4 does not necessarily accurately indicate the amount of activated sludge due to the low reliability of the sensor. Must not be. Therefore, in the above device, all of the data input to the microcomputer 7 may not function effectively to control the aeration air volume.
Despite advanced control, there are problems such as large variations in the DO value, resulting in an increase in the driving energy (in reality, electric power) of the aeration blower, and high equipment costs. was there.

Purpose of the Invention The present invention has been made to solve the problems of the prior art described above, and it is possible to stabilize biological treatment by bringing the DO value as close as possible to the target set value, and
It is an object of the present invention to provide an aeration blower control device that can reduce the power required to operate an aeration blower.

Composition of the Invention The control device of the present invention includes a DO meter that measures the amount of dissolved oxygen in an aeration tank and outputs it as an electrical signal, and samples the output value of the DO meter at regular intervals and sets the value as a target DO value. Required aeration based on the control deviation if it deviates from a predetermined gap width centered on 1! An air flow controller that determines lfi by proportional-integral control and a variable air flow type aeration blower that is necessary to obtain the required aeration amount. a number controller that determines whether or not to drive the variable air volume and constant air volume aeration blowers or the required number of them to be driven, and an inverter that controls the variable air volume aeration blower by frequency conversion control,
Illll variable type aeration blower I! When 1 m is the lower limit for a certain period of time, the number of driven suspended aeration blowers is reduced, and the air flow rate by the variable air volume cold air pro' is increased to 17 limits, and the air flow ff1fi by the aeration blower is increased between the eyebrows. When the specified time limit is reached, the number of constant air volume aeration blowers driven is increased, and the air volume variable type aeration blower is used to send I! It is characterized by being configured to lower the I-hang to the lower limit.

EMBODIMENTS Embodiments of the present invention will be described with reference to FIGS. 2 to 4.

FIG. 2 is a schematic diagram showing an embodiment of the present invention, in which an aeration tank 20 receives wastewater 21 from a molded structure from a predetermined location, and processes it from an opening on the opposite side of the inflow section. The air diffuser 23, which is configured to cause water 22 to flow out and is placed at the bottom of the aeration lW2O, is communicated with an air main pipe 24, and the air main pipe 24 is connected to a variable wind blower 2.
5 and multiple (three in the figure) constant air volume blowers 26a
, 26'b, and 26c in parallel. Aeration tank 2
From the inflow part to the total length β from the inflow part of the waste water 21 to the outflow part of the treated water 22 at 0! The DO meter 27 for measuring the DOfia inside the canister tank 20 is installed at the x2/3 position. The total length of the waste water 21 flowing into the aeration tank 20! 2. While the activated sludge flows through approximately 1.3', the multiplication of activated sludge due to aeration, that is, the decomposition of pollutants, is completed, and after that, dissolved oxygen is consumed only for the survival of the sludge, so the DO value at the above-mentioned position is This is because it serves as an index that appropriately represents the degree of purification. That DO
Total 27 has a configuration that outputs the measured value as an electrical signal, and has an I! lfJ control unit 2 control is connected to -C.

A number controller 29 is connected to the air volume controller 28, and these IuIffi controllers 28 and the number controller P
A relay control panel 30 is connected to each of the two II units.

To explain the functions of each of these controllers 28, 29 and relay control panel 30, I! 1m controller 28 is the DO
The configuration is such that the required exhalation I @ suspension is controlled based on the amount of deviation between the DO value input from the total 27 and the set value which is the target DO value. Here, the gear V point is within a predetermined range (gear...17 range) centered around the set value (= DO value), even if there is a deviation between the DO injection and the set value. The operation color does not change even if the operation color is changed (this is a setting width to allow two different operations to continue. Also, a sample is a set of input colors that are input every predetermined recombination time (for example, 30 seconds). If there is a difference in the width of the [)0 value within the sample time, the DO value is divided into one night, and if there is a difference in the width of the [)0 value within that sample time, then
This means that the control is executed for only one second) and the manipulated variable is not changed for the remaining time. Furthermore, l) I indicates that the control action is a proportional/integral action. Therefore, the air volume controller 28 transmits the response during air volume control with a first-order delay with respect to the Do measurement value, and the response time of the D OKt 27. This corrects the wasted time caused by this, and prevents temporary fluctuations in the measured value of the DO meter 27 from affecting the operation color. In addition, the number controller 29 controls the required aeration 1! determined by the air volume controller 28! The blower 25.26a so that Ht
-26c tyt+-a-, and more specifically, when the DO value changes significantly and the amount control by the variable blower 25 becomes insufficient, the constant air amount is This configuration controls the mold blower 26 (ON/A of 1 to 26c). - i.e. during dose control the FJ1
The operator of the fi controller 28 operates any or all of the stationary suspended blowers 26a to 26c when the sound remains at a limited stop for a predetermined period of time (for example, 600 seconds) or more. By outputting a start signal to the relay control 130 and inputting an iE operation completion signal from the relay control panel 30, the amount of air flowing to the variable air flow meter 25 is lowered to the lower limit, and the flow is reversed. The operation color of M fi Itl + control 28 is set for a predetermined period of time (for example, 600 seconds) L/
When the upper and lower limit values are reached, the constant air pressure valve [1W26
By outputting a stop signal from the relay control panel 301 and inputting a stop completion signal from the relay control panel 30, the variable air volume blower 25 is activated to stop any or all of a to 26c. It is configured to raise the Il gate to the upper limit.

The variable indication blower 25 is connected to an inverter (frequency converter) 31.1. /- is connected to the control device 30, and the shell hanging control (Liu device 2B's 1 2 1 2B frequency conversion (J) increases or decreases the kite sending power 72, so the wind control device i) The amount of air blown is configured to be maximum or minimum depending on whether the operation amount of !1i28 reaches the upper limit or the lower limit.

In addition, the number controller 29 is connected to the constant calm type block 26a.
In addition to the on/off control function of 26C, there is also an interlock (
Functionality, increase/decrease in the number of drive units, cyclic operation capacity, and intermittent operation! It is equipped with a gate, that is, an intermediary function is fixed J! 1. If one of the ffi blowers 26a to 26c stops, it is a function that keeps that blower in a stopped state for a certain period of time using a timer, etc., and only the same blower is turned on and off frequently. Maybe the late V? It is designed to prevent In addition, if the number of drives is increased (1), the tilt variable blower 25
In addition, one fixed JUL'S type blower is installed.
This is a function to control one or more other M-type blowers in cases where it is not sufficient to control the M-type blowers. In addition, the zaiclic operation function uses multiple constant air volume blowers 26a.
This is a function that automatically switches the starting and stopping order of ~260, and this function allows each fixed J! In type) [ ] Wa 26a~2
The operating time of the 6C is averaged and a particular blower is prevented from reaching the end of its life prematurely. Furthermore, the skip operation function is a function that, when an accident occurs with a blower, operates the blower next to the blower.

First, the operation of the above-mentioned device will be explained.

FIG. 3 is a diagram showing changes over time in the DO value obtained by the DO meter 27, the inverter operation amount for the variable air flow blower 25, the number of blowers in operation, and the aeration am. The DO value in the aeration tank 20 is measured by a DO meter 27, and the measured value is input to the air volume controller 28. If the DO value is equal to or less than a predetermined gap width centered around a set value set in the air volume controller 28, the air volume controller 2
8 ゛ outputs a signal, and as a result, the inverter operation amount increases, and l! Since the rotation speed of the variable blower 25 is increased, the aeration air volume increases. As the aeration flow increases, the DO value improves, but when the DO value falls within the gap range, the pulling sacred treasure 28 detects the amount of error and keeps the operator constant.
As a result, since the inverter operation amount becomes constant, the amount of dizziness also becomes constant. In this way, the 18 in the tank 20
[If the amount of sulfur supplied to the water 21 exceeds the amount of oxygen consumed by activated sludge due to progress of purification, etc.], DO
The value increases.

continue. ( ) If the 0 value exceeds the gap range, the amount of dissolved element in the waste water 21 will be unnecessarily large, so the air volume controller 28 outputs a signal to reduce the expiratory volume based on the amount of deviation. As a result, the inverter operation amount decreases and the number of aeration kites n decreases.

In that case, the suspension control unit 28 performs the Giseppu number Pl control. [Because of this configuration, for example, control based on the control deviation is executed for only 10 seconds out of a sample time of 30 seconds, and the remaining 20 seconds are maintained by the operator after the control is executed.

Therefore, the inverter operation amount (that is, the variable F, J!l variable number of rotations of the variable blower 25) changes stepwise as shown in FIG.

After a predetermined time (for example, 600 seconds) has elapsed after the inverter operation amount has been reduced to reach the lower limit value, the output signal from the r@most secondary controller 28 causes the control board 30 to set the One of the air volume blowers 26a-260 is stopped, and the number of operating blowers changes from 0 to (n-1).
Reduced to the table. Further, the air volume controller 28 operator reaches the upper limit due to the stop completion signal from the relay control panel 30, and as a result, the inverter operator reaches the upper limit. In other words, the decrease in expiratory volume due to the stoppage of one of the stationary type blowers is compensated for by increasing the rotational speed of the same volume variable type blower 25 to the maximum. After that, the inverter operation amount is lowered stepwise at each sample time based on the deviation of the DO value from the set value. When the DO value falls within the gap range, the air volume controller 28 considers the deviation amount to be zero, and the inverter operation amount for mu becomes constant, and as a result, the exhaled air is maintained at the previous F@most. If the amount of oxygen supplied to the waste water 21 in that case is less than the amount of oxygen consumed by activated sludge, the Do value continues to decrease. When the Do value falls below the gap range, the inverter operation amount increases and the aeration air volume increases, but if the inverter operation amount reaches the upper limit and a predetermined period of time (for example, 600 seconds) has passed, the operating blower Since the capacity is insufficient [J], the relay control board 30 activates one new air flow blower based on the output signal of the wind control instrument 28. Also, relay control board 3
The operation amount of the air volume side circuit 28 increases to the upper limit due to the startup completion signal from O, and accordingly, the impark operation amount becomes the upper limit value. After that, the inverter operation amount increased step by step due to the gap sample P■ control, and the aeration ff1ffi
gradually increases. When the Do value falls within the gap range, the inverter operation amount remains constant as described above, and the expiratory volume becomes constant.

In addition, while controlling as described in section 2, if the number of blowers in operation is reduced from n to (old -1) and 011f still does not decrease, inverter control 0 becomes the lower limit value again. Therefore, the number of operating blowers is further reduced by one. Further, if the number of operating blowers increases by one and the o value still does not rise, the inverter operation amount reaches the upper limit again, so the number of operating blowers increases by one more.

In this way, the above-mentioned device has a Do value of 1! As can be seen from the fluctuations in Ifi, the response of windage control is transmitted in a linear manner with respect to the DO value, and
27, the wasted time due to response delay can be corrected, and D
O! Since the measurement at t27 does not particularly affect the amount of operation, the air volume can be controlled reliably. Therefore, the treatment with activated sludge can be stabilized, and since the exhaled air pressure does not become excessive, combined with the inverter control of the blower, the energy consumption by the blower can be reduced to the necessary minimum.

Next, an experimental example conducted to confirm the effect of this excuse device will be shown together with a comparative example.

Example of the present invention Processed water amount: 9.500 m3/'day Blower: 20-58+n' 7 minutes X O, 5 kg (i
ci x 75kw 1 group 581y13/minX O, 5kQf/'cK X 75
kW 'I group 20m3/min x O, 5k! lf/ctX
55kw 2 unit operation time: 241+r/day x 100 days - Do value is 1.6 for equipment with 2,400hr or more
ppm.

Comparative Example In the equipment shown in the above example, DOliI is 1.6
The blower was feedback-controlled so that pp+n.

The change in Do value over time in the inventive example and the comparative example is the fourth
It was as shown in the figure. As is clear from the results shown in FIG. 4, it is recognized that according to the apparatus of the present invention, the fluctuation range of the DO value is extremely small and stable. Furthermore, when the degree of purification was investigated, the results shown in Table 1 were obtained.

As is clear from the results shown in Table 1, the device of the present invention has less fluctuation in BOD value and is 34% lower than the conventional device.
The BOD value can be reduced to a certain degree, and wastewater purification is excellent.

Furthermore, in the comparative example, 3,002 kwH/day x 30 days/month = 90.060 kwH/month of power was consumed, but in the inventive example, 1,910 kwH/day x 30 days/month = 5
Consuming 7,300kwH/month of electricity, the total amount was 32.76
It was recognized that there was an energy saving effect of 0 kwH/' month.

Effects of the Invention As is clear from the above explanation, the aeration blower control device of the present invention has a small range of fluctuations in Do and BOD values, stabilizes small plants, and prevents siltation caused by activated sludge. Since it can be done in a calm manner and there is no need to exhale unnecessarily, the performance is 1τ width compared to the previous one. .

[Brief explanation of the drawing]

Figure 1 is a schematic diagram showing an example of a conventional reactor air blower control.
The figure shows DO value, inverter operation time, number of units in operation, and aeration I! Diagram showing the most temporal change, Figure 1 1=1
*Invention example and comparative example J, ; t-fruit F'l ['
) This is a graph showing the fluctuation of O bribe. 20...is the gas phase, 25...I! 'l variable type blower, 26a, 26b, 26cm...fixed' @ Siblowa, 28-1! 1 section controller, 29... number control unit, 31... inverter. Applicant Toyota Motor Corporation Representative Patent Attorney Oath 1) Hisashi Takeshi (1, T or 1 person) Figure 1 5 t. Figure 2

Claims (1)

[Claims] In wastewater treatment equipment, the amount of dissolved oxygen in the aeration plant was measured using a variable air volume aeration blower and a fixed type (I-type aeration blower blows air into the wastewater to be treated in the aeration plant to perform activated sludge treatment). A DO meter that outputs as an electrical signal, and a D
The output value of the o meter is sampled at regular intervals, and if the value is out of a predetermined gap width centered on the IDO value, the required one-ki equivalent amount is determined by proportional-integral control based on the control deviation. Kite 1! a controller, a number controller that determines the amount of air blown by the variable air volume aeration blower necessary to obtain the required aeration amount, and whether or not to drive the constant air volume aeration blower or the required number of units to be driven; The J! I raise the air flow rate of the variable air volume aeration blower to the upper limit, and increase the number of constant air flow type aeration blowers driven when the air flow rate of the variable air volume aeration blower is at the upper limit for a predetermined time, and increase the air flow rate of the variable air volume aeration blower. An aeration blower control device for wastewater treatment equipment, characterized in that it is configured to lower the air volume to a lower limit.