JPS61192392A - Calculation of aeration air amount - Google Patents

Abstract

PURPOSE:To perform proper air amount distribution, by resetting an integration term when the sum total of demand air amounts of systems exceeded the max. supply air amount of an air feed source. CONSTITUTION:An integration term setting device 25 performs the resetting of an integration term represented by formula when the sum of the demand air amount Qr1 of a system 1 and the demand air amount Qr2 of a system 2 exceeded the max. supply air amount QM of an air feed source 15 to output the previous integration term QI10ld (QI20ld). Previous integration terms RI10ld, RI20ld are supplied to the demand air amount calculator 21 of the system 1 and the demand air amount calculator 22 of the system 2 to calculate demand air amounts Qr1, Qr2. The demand air amounts Qr1, Qr2 are supplied to a feed air amount distribution control apparatus 40 to calculate the air amount order value QS1 of the system 1 and the air amount order value QS2 of the system 2 and the supply of air to tanks 1, 2 is performed on the basis of these order values.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a method for calculating the amount of aeration air suitable for use in a sewage treatment system using the activated sludge method, and particularly relates to a method for calculating the amount of air supplied from an air source in all multiple series of air. This aeration system allows for appropriate air volume distribution even when the sum of the required air volume of each series exceeds the air volume supplied from the air source when the air is distributed and supplied to the ration tank (hereinafter referred to as air tank). Regarding the air volume calculation method.

[Conventional technology]

The applicant first asked about the amount of air supplied from a single source of air? We proposed a dissolved oxygen concentration control device that solved the various problems that occur when distributing and supplying air to multiple lines (patent application filed in 1973).
No. 9-276583).

FIG. 2 is a block diagram showing the configuration of the nine devices proposed earlier. In this figure, four blowers 15-1 to ]5-
Air discharged from a single air source 15 consisting of four air blowers passes through a conduit 18 and is distributed to the air tongues 1 of the series 1 and the air tongues 2 of each series.

This distribution is performed by interposing between the air source 15 and the air tank 2.
This is done by controlling the opening degree of the regulating valve 30 and the amount of air discharged from the air source 15.

First, the discharge air volume of the air source 15 is as follows:
-4 operating units and the opening degrees of the suction valves 17-1 to 17-4. is executed by the suction valve control device 38.

Further, the opening degree of the control valve 30 is determined by the air flow distribution control device 4.
An output of 0 causes the regulating valve control device 39 to adjust.

The above-mentioned air flow distribution control device 40 outputs the required air volume -1 of series 1 which is output from the required air volume calculation device 21 of series l and the required air volume calculation device 22 of series 2? tQr] and series 2
Based on the required air fQ r 2 , the discharge air volume and discharge pressure of the blower source 15 are calculated, and this? In order to achieve this, the number of blowers in operation and the suction valve opening are determined and the above control 2 is performed, and the required air volume Qrl, Qr2' of each series is determined.
1-Determine the opening degree of the control valve 30 to satisfy the
ft control.

The above-mentioned required air volume calculation device 21.22 is a D of air tongue 1°2.
O [dissolved oxygen] value DOI, DO2ke target value DO
8I, air volume required to maintain DO82? ,
One calculation is made for each proportional-integral operation.

First, the required air volume calculation device 21 calculates the DO for each control period ΔT.
DO value DOI from target value DO8I to air tongue]
? Subtract to find DO deviation value ΔDOI, and DO deviation value ΔD
When the OI is outside the dead zone, the PI calculation unit 23
Perform the following calculation to obtain the required air volume Qrl of series 1.
? Calculate.

(1) Calculation of the proportional term The preset proportional gain is 1 and the DO deviation value Δ
Calculate the proportional term Qp+ of series 1 from DOI and ).

Qpl=1・ΔDOI・・・・・・・・・・・・
...(1)(2), Calculation of integral term Preset control period ΔT, integral time TI, integral term C in the previous control period stored in memory, previous integral term IQ11o1aρλ, etc. Integral term QII in the control period? calculate.

・・−・・・・・・・・・・・・・＋21(3)
Calculating the required air volume Add the proportional term Qpj and the integral terms Q and TI to obtain the required air volume flQr of series 1! Find f, Qr 1 =Qp 1 +QI 1 ・・・−・−
...and...----... (3) (4) Set of integral terms This time's integral term Q11? , is stored in the memory as the previous integral term QI 1 old in the next control cycle.

Qi1o'ld 4- QII =...----
(4) On the other hand, the required air volume calculation device 22 calculates the proportional term Qp2 % integral term QI2 and the required air volume Qr2 f of series 2 in exactly the same manner, and calculates the integral term QI2 f the previous integral term Qi2o1d in the next control cycle. be memorized as .

In this way, the integral terms QIt and Ql2 are determined by the DO deviation value Δ
I")01, when ΔDO2 is on the positive side of the dead zone, the DO deviation value ΔDOt in each control period
#ΔDO2 is integrated and continues to increase, and when it is on the negative side, it continues to decrease. Also, DO deviation value Δ, T)Ql,
When ΔDO2 is within the dead zone, is it a constant value? (see C formula (2)).

[Problem that the invention seeks to solve]

By the way, in the above-mentioned apparatus, the sum of the required air volumes Qr1 and Qr2 of series 1.2 is Qr=Qr1+Qr2...
・・・・・・・・・・・・・・・・・・・・・・・・(5
) exceeds the maximum supply air volume QM of the air source 15, the air supply volume to the air tongue 1.2 becomes the required air volume Qrl @
Since it is smaller than Qr2, D of air tongue 1.2
O value DOI and DO2# will not rise sufficiently.

That is, as shown in FIG. 3, the required wind is 11Qr+.

Sum of Qr2 Qr7'li Maximum supply air volume QM of air blowing source 15? When it exceeds, the required air volume Qrl and Qr2
The maximum air volume that can be supplied while maintaining the distribution ratio of Qiml
.

Details of how to distribute air to air tongue 1.2 using Ql2 as the air volume command value are given in Japanese Patent Application No. 59-276.
(See No. 583). However, as is clear from Figure 3, 0 nights 1〈Qrl ・・・・・・−・−・・・・・・
・・・・・・・・・・・・・・・・・・(e) Qs2
〈Qr2・・・・・・−・・・・・・・−・・・・−
・・・・・・・・・・・・(7) Therefore, air tongue 1
．． The air volume supplied to No. 2 is lower than the required air volume Qrl, Qr2 (DO value D01).

Difference between DO2 and DO target values DO8I and DO82, that is, DO deviation value ΔDO1 (=DO81-DOI)s
ΔDO2 (=DO82-r102) gradually increases.

Therefore, the integral term QIt (OI2
) increases monotonically, and the required air volume Qrl, Qr2
The difference between the air volume command values QIBI and Q82 of each series will also gradually increase.

If such a state continues, the following two problems will occur.

Even if the fil DO values D01 and DO2 recover, the integral terms QI> and Ql2Vi do not recover immediately, resulting in overaeration.

In the case of an activated sludge process, even if the DO value continues to be low due to insufficient supply air volume, the DO value may rise due to changes in the water quality of the inflow water, changes in the ecological characteristics of microorganisms, etc.
DO value exceeds target value, now supply air volume? If the integral terms QIt and OI2 are too large, the required airflow 1tQr1 and Qr2 will not be reduced due to force, resulting in overaeration.

(21) Appropriate air volume distribution cannot be achieved.

As described above, the air volume distribution to series 1.2 is made according to the ratio of the required air volumes Qrl and Qr2.

That is, the air volume command value Qθ1 for series 1.2.

Qs2 is, Q82=3 permissible needles, ・QM・・・・・・・・・・・・・
・(9) 9th day 1 + Q s 2 = QM ・・・・
・・−・・・−・−・・・・・・・・OI However; QM is the maximum supply air volume of the air source 15.

In this case, for example, if DO@DOL of series 1 is low and the DO value DO2 of series 2 is in the sensitive zone 1, the required air volume Qrl of series 1 increases monotonically, and
The required air volume Qr2 is constant. Therefore, the air volume command value Qsl to series 1 gradually increases while
The air volume command value Qs2 to 11% series 2 gradually decreases as shown in equation C (91), and the DO value D of series 2 enters the dead zone.
A failure occurs where O2 is disturbed by the circumstances of series 1.

This invention was made in view of the above-mentioned circumstances, and solves the problem of fi+ (21) described above, and enables appropriate air volume distribution even when the total required air volume exceeds the maximum supply air if of the air blowing source. The purpose of this paper is to provide a method for calculating aeration wind noise that can be carried out.

〔problem? Means to solve]

In order to solve the above problems, this invention provides that when the sum of the required air volumes of each series exceeds the maximum supply air volume of the air source,
For each series, a value obtained by subtracting the proportional term of the series from the air volume command value assigned to the series is used as the integral term of the series in the next control cycle.

[Effect]

By the above means, n can prevent the required airflow 'IA' from increasing monotonically, and it becomes possible to perform appropriate air volume distribution.

This reason will be explained using an example of series 1f.

Now, the integral terms QII fil , QII f2 of the sequence l in the control period 1.2.3...n-1, n...
1...QI+rn-1), Qllrnl... are considered. If the sum of the required air volumes of each series exceeds the maximum supplied air volume of the air source 15 in the (n-1)th control cycle, then the previous integral term Q of series 1 in the n-th control cycle
iiold lnl is the air volume command value Qsl of series 1 at the (n-11th) (from n-11 to the proportional term Qp
> (n −1), so −Ql 1
old 1nl=Qs 3 (n-11-Qpl(n-
13=Qsj (n-11-K・Δ1)Qlln-1)
...(lυ. In other words, the previous integral term QJxoldrnl of series 1 is the DO deviation value ΔDO
is not integrated, and is reset to a value smaller than the air volume command value Qatrn'-1) assigned to series l.

At this time, the required air volume Qrl(n) of series 1 is +Q
811n-11-K・ΔDOI (n-11-・-J1
2i, and when ΔDOI(n-11, ΔDO1rn) is in the dead zone, Qrl(n)=Qsl(n-1) ・・・・・・・・・=
−””(J31. Also, Δp01(n-1) #
Even when ΔDQ1(nl is positive, the integral term is reset by the formula (Ill, so the required air volume Qr](
n) does not increase monotonically.

Therefore, it is difficult to quickly follow up when the DO value recovers.
At the same time, it is possible to eliminate the negative influence on other series.

Although the above calculation has been explained for the example of series 1r, similar calculations are performed independently for other series as well. [Embodiment] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing the configuration of essential parts of an embodiment of the present invention, and the other configurations are the same as in FIG. 2.

In this figure, 25 is an integral term setter.

The integral term setter 25 determines whether the sum of the required air volume Qrl of series 1 and the required air volume Qr2 of series 2 is the maximum supplied air volume QM? When the value is exceeded, the integral term is calculated as shown in equation (11), and the previous integral term
16. (Q 2 o 1 dlft is output. This previous integral term QI J old and QJ20ICI are each series l
The required air volume Qr of each series is supplied to the required air volume calculation device 21 and the required air volume calculation device 22 of series 2.
l, Qr2 are calculated. Hereinafter, the above-mentioned required air volume Q" * Qr2 is supplied to the air volume distribution control device 40, and the air volume command value Qsl of series l and the air volume command value Qθ2 of series 2 are calculated, Based on this, air is supplied to the air tongue 1.2.This method of distributing air volume is detailed in Japanese Patent Application No. 59-276583, so the explanation thereof will be omitted.

〔Effect of the invention〕

As explained above, in this invention, when the sum of the required air volumes of each series exceeds the maximum supply air volume of the air blowing source, the integral term is reset, so does the required air volume increase monotonically? It can be prevented.

As a result, the following effects can be achieved.

+11 When the DO value recovers, it can be quickly lowered to an appropriate value by the required air volume.

(2) Is it an inconvenience that the required air volume of the Uru series increases monotonically, resulting in a shortage of air volume supplied to other series? It can be resolved.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of essential parts of an embodiment of the present invention, and FIG. 2 is a block diagram showing the configuration of a dissolved oxygen concentration control device proposed in Japanese Patent Application No. 59-276583. FIG. 3 is a graph for explaining the state when the sum of the required air volumes of each series exceeds the maximum supply air volume of the air blowing source. 1.2...Air tongue (aeration tank)
, 15...Blow source, 25...Integral term setter, 40...Blow volume distribution control device.

Claims (1)

[Scope of Claims] When distributing the amount of air supplied from an air source to a plurality of series of aeration tanks, (a) for each series, the DO value and D of the aeration tank;
Obtain the DO deviation, which is the difference from the O target value, in a predetermined control cycle, (b) perform a predetermined calculation on the DO deviation to calculate a proportional term and an integral term for each series, (c) Determine the required air volume for each series by the sum of the proportional term and the integral term, and (d) distribute the air volume supplied from the air source according to the required air volume for each series to achieve aeration for each series. In the aeration air volume control method for supplying air to a tank, when the sum of the required air volumes of each series exceeds the maximum supply air volume of the air source, the following calculation (e) is performed for each series to An aeration air volume calculation method characterized by resetting the integral term each time. (e) The value obtained by subtracting the proportional term of the series from the air volume command value of the series determined by the air volume distribution in item (d) above is set as the previous integral term of the series in the next control cycle.