JPH0122837B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an air volume control method in a ventilation system that blows gas such as air into a tank system of a sewage treatment plant or the like.

Generally, in sewage treatment plants, aeration treatment using activated sludge is carried out as one step in the treatment process, and the equipment for this is usually an aeration tank system consisting of multiple tanks, and a system for this tank system. An air blowing system is installed, which includes a blower for blowing gas to.
Conventionally, as a method for controlling the air volume of such a ventilation system,
A control method using a control system shown in FIG. 1 is known. To explain the air blowing system A shown in the figure, reference numeral 1 indicates a blower. This blower 1 is
It is installed in the middle part of the pipe line 2. Further, the pipe line 2 located on the suction side of the blower 1 is provided with a suction air volume detector 3 and a suction air volume adjustment valve 4. Further, the pipe line 2 is branched into a plurality of sub-pipe lines 6, 6 on the discharge side of the blower 1, and each sub-pipe line is connected to an aeration tank 8, by inserting a manual valve 7, 7.
8 is connected.

Further, the control system B that controls the air volume of the air blowing system A described above includes a calculation section 9, the suction air volume detector 3 that supplies a detection output to the calculation section 9, and the calculation section 9.
and a suction air volume control valve 4 that is operated by an output signal supplied from the air intake valve 4.

The blower system A configured as described above includes a blower 1
is used to blow air to each aeration tank 8, 8, and the amount of air distributed to each aeration tank 8, 8 is adjusted by operating manual valves 7, 7. At the same time, the entire air blowing system to all the tanks 8, 8 is controlled by the control system B in accordance with the opening degree of the manual valves 7, 7. That is, the detection output from the suction air volume detector 3 and the air volume command value are input to the calculation unit 9, where they are converted into an output signal corresponding to the opening degree required of the suction air volume control valve 4, and this output The suction air volume detector 4 is operated based on the signal, thereby controlling the total discharge air volume.

By the way, normally in a sewage treatment plant, facilities with the minimum necessary treatment capacity are constructed at the beginning of construction, and then when it becomes necessary to expand the treatment capacity due to population increase, for example, various facilities are expanded. We are expanding and expanding our facilities, and as these facilities expand, we may add aeration tanks, etc. The addition of such a tank system complicates the operating conditions of the blower system, and for this reason, controlling only the total airflow to the tank system as in the conventional airflow control method described above does not allow for appropriate control of each tank. It was difficult to blow the appropriate amount of air.

In view of the above circumstances, it is an object of the present invention to provide an air volume control method that can be applied to a large-scale ventilation system or a ventilation system that has been expanded due to expansion, and can blow an optimal air volume to each tank. Each tank system is equipped with a discharge air volume control valve and an air volume meter, and in contrast to the conventional control of the total air volume, the air volume to each tank system is controlled based on the control valve and air volume meter. This system is characterized by supplying the optimum amount of air to the system.

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 2 is a diagram for explaining the present invention.

First of all, to explain the ventilation system D in the figure, reference numeral 1
1 is the main pipe. In the middle part of the main pipe 11,
A blower 12 is provided. Also, blower 12
The pipe line located on the suction side is equipped with a suction airflow detector 1.
3 and a suction air volume control valve 14 are provided. On the other hand, a pressure detector 15 for detecting the discharge pressure from the blower 12 is provided in a conduit located on the discharge side of the blower 12 .

Furthermore, the main pipe 11 is equipped with a pressure detector 15.
The first tank system is branched at a later stage, and each end is connected to a first tank system 16 consisting of a plurality of aeration tanks (only one is shown in the figure) and a second tank system 17 as an extension. and second sub-pipes 18 and 19 are connected. In this case, the second auxiliary pipe line 19 is provided with a discharge air volume detector 20 and a discharge air volume control valve 21 . Also, the first
The second tank systems 16 and 17 are equipped with required air volume detection meters (in this embodiment, DO meters are used to detect the required air volume (required air volume) of each tank system 16 and 17). 22 and 23 are provided for detecting the DO value of the liquid content and detecting the required air volume based on the DO value.

Although not shown, the first and second tank systems 1
The plurality of aeration tanks 6 and 17 are each provided with an inlet pipe for introducing air from the first or second sub-pipe line 18 or 19 via a manual valve.

Next, the control system C that controls the above-mentioned ventilation system D will be explained. This control system C includes a first calculation section 31, a second calculation section 32, a third calculation section 33, a first adjustment section 34, a first detection section 35, and a suction section provided in the main pipe 11. Air volume detector 13 and suction air volume control valve 14
a pressure detector 15, a discharge air volume detector 20 provided in the second sub-pipe 19, and a discharge air volume control valve 21.
and required air volume detectors 22 and 23 provided in the first and second tank systems.

Next, a method for controlling the above-mentioned ventilation system D by the control system C will be explained. In addition, in the following explanation,
The term "equivalent" in terms such as "required equivalent dynamic resistance coefficient", "equivalent dynamic resistance coefficient", and "equivalent static pressure" collectively expresses (values of) various factors involved.
For example, in the case of "dynamic resistance coefficient", the characteristics of piping,
It is thought that it is determined by factors such as the opening degree of the valve, but these factors are collectively considered to be "equivalent".
It is called.

In addition, in the following explanation, the required equivalent dynamic resistance coefficient R _B means the dynamic pressure coefficient in Bernoulli's theorem of the discharge air volume control valve 21, and the equivalent dynamic resistance coefficient
r _a and r _b mean the dynamic pressure coefficient in Bernoulli's theorem for a tank system. Furthermore, the equivalent static pressures H ₁ and H ₂ mean the static pressures in Bernoulli's theorem.

First, the first calculation unit 31 includes a suction air flow rate detector 1
The suction air volume _i as the output of 3 and the pressure detector 1
5, the discharge air _volume as the output of the discharge air volume detector 20 (i.e., the air volume to the added second tank system 17) ₂ ,
The pressure _i and temperature T _i of the atmosphere introduced into the main pipe 11, the temperature _O on the discharge side from the blower 12, and the second
The required equivalent dynamic resistance coefficient as the output of the calculation unit 32 of
R _B is supplied. In addition, the required equivalent dynamic resistance coefficient
Regarding R _B , an appropriate value is temporarily stored in the first calculation unit 31 as its initial value, and after that, R _B calculated by the second calculation unit 32 is transferred to the first calculation unit 3.
It is designed to be used with feedback from 1. In _this first _{calculation section} 31 _{, first and second}
Equivalent dynamic resistance coefficient of each tank system 16, 17 of
Calculate r _a , r _b and equivalent static pressure H ₁ , H ₂ .

In other words, the relational expression obtained from the Boyle-Charles law _O ; Total discharge air volume of the blower 12 ₁ ; The following formula obtained based on the discharge air volume to the first tank system 16 According to the following, the discharge air volume ₁ to the first tank system is calculated. Next, the discharge pressure _O , the discharge air volume ₁ to the first tank system, and the discharge air volume ₂ to the second tank system
three detected values (in this case, ₁ is a value calculated from other detected values), the required equivalent dynamic resistance coefficient R _B from the calculation unit 32, and the first and second tank system 1.
6, 17 equivalent dynamic resistance coefficients r _a , r _b and equivalent static pressure
Equivalent to the equivalent dynamic resistance coefficients r a and r _b based on the relational expression between H ₁ and H ₂ , _O = r _a ² ₁ + H ₁ = (R _B + r _b ) ² ₂ + H _{2 ...} (3) Static pressure
Calculate H ₁ and H ₂ . In this embodiment, this calculation is performed using two sampling data _O ', O'', _{1 '} , ₁ '', _2' obtained by sampling the three detected values _O , ₁ , and ₂ at predetermined time intervals.
,
Q ₂ ″. In other words, the above sampling data _O ′, _O ″, ₁ ′, ₁ ″, ₂ ′, ₂ ″ are expressed as (3
) and calculate based on the following equations obtained as solutions to the simultaneous equations.

The equivalent dynamic resistance coefficients r _a , r _b and the equivalent static pressures H ₁ , H ₂ obtained in this way are calculated based on the respective states ( For example, it depends on the partial clogging of the discharge hole of the aeration tank, the opening degree of the manual valve, etc.

Next, the equivalent dynamic resistance coefficients r _a , r _b and the equivalent static pressure H ₁ of the first and second tank systems obtained as above are calculated.
H ₂ is supplied to the second arithmetic unit 32 as the output of the first arithmetic unit 31 . At the same time, the second calculation unit 32 has the first and second tank systems 16, 17.
Supply the required air volume data _1c and _2c for each.
In the second calculation unit 32, the relational expression obtained from the above equation (3) According to the above input values r _a , r _b , H ₁ , H ₂ , _1c ,
The required equivalent dynamic resistance coefficient R _B required for the discharge air volume control valve 21 is calculated from _Q2c . This required equivalent dynamic resistance coefficient R _B has a correspondence relationship with the opening degree required of the discharge air volume adjustment valve 21, and is used to control the discharge air volume adjustment valve 21 as described later.

Next, the above-mentioned required equivalent dynamic resistance coefficient R _B , the equivalent dynamic resistance coefficient R _b and equivalent static pressure H ₂ of the second tank system output from the first calculation unit 31, and the required equivalent dynamic resistance coefficient R B of the second tank system are calculated. The air volume data _2c and the third calculation unit 3
Supply to 3. The third calculation unit 33 calculates the required discharge pressure P _O of the blower 12 according to the following equation obtained from the above equation (3): P _O = (R _B + r _b ) _2c ² + H ₂ (3) do.

The required discharge pressure P _O and the required equivalent dynamic resistance coefficient R _B calculated as described above are converted into signals for controlling the suction air volume control valve 14 and the discharge air volume control valve 21.

In this embodiment, the first adjustment section 34 includes:
The required discharge pressure P _O and the discharge air pressure _O output from the discharge pressure detector 15 are supplied. This first adjustment section 34 adjusts the above-mentioned required discharge wind pressure P _O
and the detected discharge pressure _O , and outputs a signal S _A that controls the opening degree of _{the o} control valve 14 (for example, PID control) based on the value, and thereby controls the suction air volume control valve 14. Adjust to the required opening.

Further, in the second adjustment section 35, the required equivalent dynamic resistance coefficient R _B supplied from the second calculation section 32 is
is converted into a signal S _B that controls the opening degree of the discharge air volume control valve 21 and output.
1 to the required opening.

As described above, in the operating state of the blower system D, the control system C controls the total air volume discharged from the blower 12 by adjusting the suction air volume control valve 14, and at the same time controls the first tank system 16 and the second tank system 16. The ratio of the air volumes ₁ and ₂ distributed to the tank systems 17 is controlled by adjusting the discharge air volume control valve 21, so that the air volume to each tank system 16 and 17 is adjusted to the required air volume _1c . _2c .

In the control system C to which the present invention is applied, each tank system 1 in the operating state of the ventilation system D is
Equivalent dynamic resistance coefficient that depends on the conditions of 6 and 17 (for example, the opening degree of the manual valve of each aeration tank, etc.)
Estimate r _a , r _b and equivalent static pressure H ₁ , H ₂ , and calculate each _{tank system 16, based on these values ra , r b ,} H ₁ , H ₂ .
Since the amount of air blown to the tank 17 is controlled, it is possible to maintain an optimum air blown condition in accordance with the state of each tank system that changes (or is changed) over time.

In addition, in the above embodiment, the equivalent dynamic resistance coefficients r _a , r _b and the equivalent static pressure of the first and second tank systems
The calculation of H ₁ and H ₂ is based on the pressure _i and temperature T _i of the suction air, the suction air volume _i , the discharge pressure _O , the temperature _O on the discharge side, the discharge air volume ₂ to the second tank system, and the discharge air volume i. This was done based on the equivalent dynamic resistance coefficient R _B of the air volume control valve, but by detecting the discharge air volume ₁ to the first tank system, this air volume ₁ , the discharge air volume ₂ , the discharge pressure _O , and the required equivalent dynamic resistance were calculated. It can also be calculated based on the resistance coefficient _RB .

In addition, the required discharge pressure in the third calculation unit 33
P _O may be calculated based on the equivalent dynamic resistance coefficient r _a of the first tank system, the equivalent static pressure H ₁ and the required air volume data _1c .

Furthermore, in the above embodiment, the ventilation system D is
Although a case has been described in which the present invention has a tank system and a second tank system as an additional tank system, it is also possible to sequentially add third, fourth, . . . , n-th tank systems. In that case, a discharge air volume control valve is provided in each sub-pipe line connected to each tank system, and the required equivalent dynamic resistance coefficients are R _C , R _D , ... R _N , and the third, fourth, ... nth The equivalent dynamic resistance coefficient of the tank system is
If r _c , r _d ,... r _o , and the equivalent static pressure are H ₃ , H ₄ ,... H _o , the relational expression with the discharge pressure _O in equation (3) is _O = r _a ² ₁ + H ₁ =... It can be expressed as =(R _N +r _o ) ² _o + H _o ...(3)′. Therefore, etc., can be easily obtained by increasing the measured parameters according to the added value, and by operating the control system according to these values, it is possible to realize dynamic optimal control similar to the above example. .

As explained above, the air volume control method according to the present invention can be applied in various tank systems, for example, when the opening degree of a manual valve is changed, or when some of the pores that discharge air into the tank become clogged, etc. In addition, it is possible to always maintain the optimum air flow rate in response to changes in the conditions, and the equivalent dynamic resistance coefficients r _a , r _b and the equivalent static pressures H ₁ , H ₂ that reflect the conditions of each tank system can be maintained. Since calculation is performed by simple calculations, highly accurate values can be obtained, and therefore, highly accurate control can be easily performed.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram of a conventional air volume control system, and FIG. 2 is a diagram for explaining the present invention, and is a schematic configuration diagram of the air volume control system. 11...Main pipeline, 12...Blower, 13...Suction air volume detector, 14...Suction air volume control valve, 15...
...Pressure detector, 16...First tank system, 17...
...Second tank system, 18...First sub-pipe line, 19
...Second sub-pipeline, 20...Discharge air volume detector, 2
DESCRIPTION OF SYMBOLS 1...Discharge air volume control valve, 22, 23...Required air volume detector, 31...First calculation unit, 32...Second calculation unit, 33...Third calculation unit, 34...First calculation unit adjustment section, 35... second adjustment section.

Claims (1)

[Scope of Claims] 1. A main pipe line provided with a blower in the intermediate part and a suction air volume detector and a suction air volume control valve on the suction side of the blower, each branched from the main pipe line,
and first, second, ... n-th sub-pipe lines connected to the first, second, ... n-th tank systems, respectively,
The air volume control method for the air blowing system that blows air to the first, second, ... nth tank systems by the blower includes an air volume detector that measures the total discharge air volume Q ₀ of the blower, and a discharge pressure ₀ of the blower. A pressure detector is provided to measure the pressure, and a discharge air volume control valve and a discharge air volume detector are provided at intermediate portions of at least the second, third, ... n-th sub pipes among the sub pipes, and each of the discharge air volumes is Required equivalent dynamic resistance coefficient of control valve
R _B , R _C ,...R _N and the discharge pressure of the blower ₀ ,
Air volume of each of the first, second, ... n-th sub-ducts
Relational expression with ₁ , ₂ ,... _{o 0} = r _{a 1} ² + H ₁ = (R _B + r _b ) ₂ ² + H ₂ = (R _c + r _c ) ₃ ² + H ₃ : = (R _N + r _o ) _o ² +H _o ... (1) Based on the above, each equivalent dynamic resistance coefficient r _a , r _b , ... r _o and each equivalent static pressure of the first, second, ... nth tank system
H ₁ , H ₂ ,...H _o are estimated, and these equivalent dynamic resistance coefficients r _a , r _b ,... r _o , equivalent static pressures H ₁ , H ₂ ,...H _o and the first, second, ...Required air volume data _1c , _2c , ... of each n-th tank system
From the _above relational expression (1), new required equivalent dynamic resistance coefficients R _B , R _C ,...
Calculate R _N , and calculate the equivalent dynamic resistance coefficients r _a , r _b , ... r _o , the equivalent static pressures H ₁ , H ₂ , ... H _o , and the new required equivalent dynamic resistance coefficients R _B , R _{C , R _ _ _} The opening degree of the suction air volume control valve is adjusted based on the discharge pressure P ₀ , and the opening degree of each of the discharge air volume control valves is adjusted based on the new required equivalent dynamic resistance coefficients R _B , R _C , ... R _N . An air volume control method comprising: adjusting the air volume blown to each of the first, second, . . . nth tank systems so as to match the required air volume of each tank system.