JPS60102997A - Energy-conserving type controlling method for aerating air quantity - Google Patents

Abstract

PURPOSE:To prevent power consumption of a blower from being increased, by a method wherein air is fed into a plurality of aerating tanks from a single blower, and an air quantity regulating valve for passing air in a target air quantity required for each of the aerating tanks is provided in each air passage leading to each of the tanks. CONSTITUTION:A PID calculator 7 calculates the pressure required for feeding a maximum target quantity of air to the aerating tank 4 when the air quantity regulating valve 44 is fully opened, and the calculated pressure is used as a pressure set point for the blower. Meanwhile, a PID calculator 6 on the aerating tank side is supplied with information that the aerating tank having the maximum target air quantity is the aerating tank 4 from a maximum value detector 11, and fully opens the air quantity regulating valve 4 form the aerating tank 4. When the valve 44 is fully opened, the PID calculator 7 on the blower side performs PID calculation by using the difference between the pressure set point and an actual air pressure detected by a pressure gauge, thereby calculating a target blowing quantity for the blower 5. By this, a suction valve 10 of the blower 5 is controlled.

Description

Detailed Description of the Invention [Field of Application of the Invention] The present invention is a method for treating sewage, etc. by flowing wastewater into an aeration tank and aerating it with air blown from a blower, and by the action of bacteria present in the aeration tank. The present invention relates to a system for purifying air, and in particular to a method for controlling its blower.

[Background of the invention]

A conventional aeration tank air volume control method will be explained with reference to FIG.

Sewage flows into each aeration tank 4, 2, and 3.4, is aerated with air sent from one blower 5 to each aeration tank, and is purified by the action of bacteria.

In order to maximize the activity of bacteria in the aeration tank, the amount of oxygen dissolved in each aeration tank (hereinafter referred to as Do) must be maintained at a constant value. This value is set to approximately 4 to 5, taking into consideration the fact that 1.1) O varies in each part of the aeration tank. This D
PID calculation is performed using the deviation between the O stage setting i6 and the actual value of Do in each aeration tank 1, 2, 3.4 measured by each Do meter 21.22, 23.24. The target air volume for each tank is calculated. Note that the actual Do value in each aeration tank changes moment by moment depending on the conditions at the time, for example, the amount of newly inflowing wastewater, etc., and the PID calculation is still performed by the PID calculation unit 6.

This calculated target air volume and each air volume meter 31°32.3
Calculation is performed from P using the deviation from the actual air volume to each aeration tank measured in 3.34, and the air volume control valves 41, 42, 43, 4
4 is given an instruction command for the valve opening degree. This PID calculation and command are performed by the PIDi'J calculator 7. The air volume to each aeration tank is controlled in the above manner.

Next, control of the blower 5 that sends air to each aeration tank will be explained. This blower 5 is shared by each of the aeration tanks 1.2 and 3.4, and includes an air flow path connecting the blower 5 and the aeration tank, and the air flow control valve and the aeration tank provided in the middle of this air flow path. The energy loss of the air flow within the aeration tank is approximately the same for each aeration tank. The blower 5 is set at a pressure sufficient to meet the target air volume required in any of the aeration tanks. Using the deviation between this pressure setting value and the actual air pressure detected by the air pressure gauge 8, the target total air volume of the blower 5 is calculated. A PID calculation is performed using the deviation between this target total air volume and the suction flow rate of the blower 5 (corresponding to the actual air flow) detected by the air flow meter 9, and an opening command to the suction valve 10 of the blower 5 is issued. put out. This PI
f) Calculations and opening commands are performed by the PID calculator 7.

The reason why a plurality of aeration tanks share one blower 5 as in this conventional example is that providing a small blower for each aeration tank is disadvantageous in terms of equipment costs and maintenance.

[Problems with background technology]

In the conventional example described above, the pressure setting value of the blower 5 is set by the operator each time, taking into consideration past blower operation and the like. However, if this pressure setting value is higher than necessary, the air volume control valve 41 is used to limit the air volume sent to each aeration tank to an appropriate air volume at each time.
．． It becomes necessary to narrow down the angle to 42.43°44. However, the more the air volume control valve is throttled down, the greater the energy loss of the airflow becomes, and the economical efficiency of the power consumption of the blower deteriorates.

On the other hand, if the pressure setting value is lower than necessary, the required air volume cannot be secured in each aeration tank. Therefore, the operator had to set an appropriate pressure setting, which required a lot of time.

[Purpose of the invention]

The present invention prevents the blower from generating more air pressure than necessary, which increases the power consumption of the blower, and also prevents the generation of an unnecessarily low air pressure, which makes it impossible to secure the target air volume of each aeration tank. To provide an energy-saving aeration tank feed rate control method that can prevent this and reduce the labor of an operator. The purpose is to

[Summary of the invention]

The energy-saving aeration tank air volume control method of the present invention controls the air blowing pressure corresponding to the aeration tank having the largest target air volume.

That is, the maximum target air volume value at a predetermined time is selected from among the target air volume required by each aeration tank at a predetermined time, and the air volume control valve of the aeration tank having this maximum target scenery value is fully opened, and the aeration is performed with the air volume fully open. The pressure required to send this maximum target air volume to the tank is generated when the air is blown at a predetermined time.The predetermined time differs depending on the control type, and may be at regular intervals, or at a certain arbitrary time. Sometimes it happened at the time.

This prevents the air pressure generated by the blower from becoming higher than necessary. Moreover, since each of the other aeration tanks has a target air volume smaller than the maximum target air volume, the target air volume can be sufficiently secured by the air pressure generated by the blower.

The above is based on the condition that the energy loss of the air flow in the air flow path, air volume control valve, and aeration tank is almost the same for each aeration tank, but most of the energy loss in the air flow is This condition is satisfied if the type of aeration tank is the same in each aeration tank.

[Embodiments of the invention]

An embodiment of the present invention will be explained with reference to FIG.

Note that the same elements as in FIG. 1 are given the same numbers and their explanations are omitted. Since sampling control is performed at a predetermined time, that is, in the present embodiment, the DO value is measured at predetermined time intervals and each target air volume is calculated.

Each aeration tank 1, 2°3. calculated by the PID calculator.
Each of the four target air volume values is sent to the maximum value detection device 11, and the maximum target air volume value is selected. At the same time, an aeration tank having the maximum target air volume value is also identified.

Now, if the aeration tank having the maximum target air volume value is the aeration tank 4, the information that the aeration tank having the maximum target air volume and the maximum target air volume value is the aeration tank 4 is transmitted from the maximum value detection device 11 to the blower side. It is sent to the PID calculation device 7 of. According to the above information, the PID calculator 7 calculates the pressure required to send the maximum target air volume to the aeration tank 4 when the air volume control valve 44 is fully opened, and uses this as the blower pressure setting value.

During this time, the PID calculation device 6 on the aeration tank side receives information from the maximum value detection device 11 that the aeration tank having the maximum target air volume value is the aeration tank 4, and fully opens the air volume control valve 44 of the aeration m4.

When the air volume control valve 44 is fully open, the PI on the blower side
The D arithmetic device 7 uses the deviation between the pressure setting value and the actual air pressure detected by the pressure gauge 8 to perform PID calculation, and operates the blower 5.
Calculate the target air blowing sound.

As a result, the suction valve 10 of the blower 5 is controlled, and the actual air volume is controlled.

The opening degrees of the other air volume control valves 41, 42, and 43 are determined by PID calculation as in the conventional case. Since the pressure setting value of the blower 5 is lower than before, the opening degree of each of these valves becomes larger.

According to this embodiment, the air pressure generated by the air blower (Table 5) is the minimum necessary.This makes it possible to generate a higher air pressure than necessary and increase the power consumption of the blower 5, which is more economical than in the conventional case. In the sewage purification system like this embodiment, the power consumption of the blower 5 accounts for more than half of the power consumption, and making the operation of the blower plate more efficient as described above is a system improvement. This is advantageous for overall economics.

In the other aeration tanks 1, 2.3, the respective target air volumes can be sufficiently secured with the minimum pressure generated by the blower 5. That is, these aeration tanks 1.2.3 only have a smaller target air volume than the aeration tank 4, and furthermore, the air flow path, the air volume control valve, and the energy extraction of the air flow in the aeration tank are different from the aeration tank 4. This is because the conditions are almost the same.

The effects of this embodiment will be explained in more detail with reference to FIGS. 3 and 4. FIG. 3 shows the energy loss curve of the air flow path, the air volume control valve, and the air flow within the aeration tank for each aeration tank. Since the energy loss of this air flow is under substantially the same conditions for each aeration tank, the difference in each energy loss curve is caused by the opening degree of each air conditioning valve 41, 42, 43, 44. The target air volume values of each aeration tank 1t2°3, . . . 4 are represented by A, B, C, and D in order. Conventionally, the air pressure generated by the blower 50 was set at a higher position J in order to obtain each target air volume. On the other hand, in this embodiment, since the air volume control valve of the aeration tank 4 is fully opened, the pressure setting value of the blower 5 can be set lower than the conventional pressure setting value J, and the maximum target air volume can be ensured. Air volume control valve 41 is also installed for each of the other aeration tanks 1.2゜3.
By increasing the opening angle of , 42°, 43°, the target air volume value ABC can be secured. In addition, each energy loss curve 11' of each aeration tank, L2' + Ag' +
14' is the conventional energy loss curve 41 + t2 +
The reason why it is slower than t3 + t4 is because the opening degree of each air volume control valve has become larger.

Now, the power consumption of the blower 5 is determined by the product of the air pressure generated by the blower 50 and the air pressure. In Figure 3, the vertical axis is pressure P.
1 Since the horizontal axis is the taste Q, the conventional consumption output is square 0AIJ, 0BIIJ.

This is the total area of 0CGJ, OD['J. The power consumption in this example is 0ANR, OBMB.

OCL 几, 01) This is the total area of KR. As a result, according to this embodiment, the power consumption of the blower 5 is reduced, making it an energy-saving type.

The above will be explained using the characteristic curve of the blower 5 as shown in FIG. The vertical axis is the air pressure P generated by the blower 50, and the horizontal axis is the air ff1Q discharged by the blower 5. In the conventional example and this example, the air flow rate is A+B10+
D- Do. The air pressure P is conventionally J, but in this embodiment, R'''C is lower than this.The characteristic curve m at each power consumption value of the blower 5 is as shown by the broken line, so in this embodiment, the It is understood that less power is required.

[Other Examples]

In the above embodiments, the air volume control means of the blower was a suction valve, but the present invention can also be implemented when using a blower having other air volume control means.

〔Effect of the invention〕

As described above, according to the present invention, the pressure setting value of the blower is determined according to the one having the maximum target air volume from among each aeration tank, so there is no waste in the power consumption of the blower, and the target air volume of each aeration tank is Air volume can also be ensured.

As a result, the power consumption of the blower and the power consumption of the entire system can be saved, and the labor of the operator who has to set the pressure setting value each time as in the past can also be reduced.

[Brief explanation of drawings]

Figure 1 is an explanatory diagram of a conventional aeration tank air volume control method, Figure 2 is an explanatory diagram of an energy-saving aeration tank air volume control method according to an embodiment of the present invention, and Figure 3 is an explanatory diagram of each aeration tank in Figure 2. FIG. 4 is a graph showing the energy loss curve of the air flowing through the air, and FIG. 4 is a graph showing the effect of this embodiment using the characteristic curve of the blower. 1.2.3.4...Aeration tank, 21.22, 23°24
...Do meter, 31,32.33.34...Air flow meter,
41.42, 43.44...Air volume control valve, 5...Blower, 6.7...PID calculator, 8...Air pressure gauge, 9...Air flow meter, 10...Suction Valve, 11... Maximum value detection device. Agent Patent Attorney Tatsuyuki Unuma

Claims (1)

[Claims] 1. A system in which air is sent to an aeration tank into which sewage has flowed, and the sewage is purified by the action of bacteria in the aeration tank, in which air is sent from one blower to a plurality of aeration tanks. The air flow path to each aeration tank is provided with an air volume control valve to flow each target air volume required by each aeration tank. In a sewage purification system where the energy loss is almost the same for each aeration tank, the maximum target air volume at a given time is selected from among the target air volumes at a given time, and the air volume control valve of the aeration tank with this maximum target air volume value is selected. An energy-saving aeration tank air volume control method characterized by fully opening the air tank and causing the blower to generate the pressure necessary to send the maximum target air volume to the fully opened aeration tank at a predetermined time.