JPS59145097A - Regulating system for flow amount of aerating air - Google Patents

Abstract

PURPOSE:To enable to continuously and properly regulate the flow amount of aerating air, by providing regulation using a blow-off valve as an auxiliary regulating means in addition to the adjustment of the opening ratios of the suction valves of blowers and the control of the number of stands. CONSTITUTION:When output from a regulator 13 exceeds a set point H, the flow amount of aerating air is regulated by controlling the number of stands and adjusting the opening ratios of suction valves 2-1-2-N. When the output for regulation becomes below another set point L, an alarm setting unit 16 is driven. A blow-off valve 8 is opened by the lower limit of the alarming output to perform exhaustion. When the output for regulation exceeds the set point H (a value slightly higher than the set value L), said blow-off valve 8 is closed by the upper limit of the alarming output to perform the regulation of the flow amount of aerating air on the basis of the control of the number of stands and the adjustment of the opening ratios of the valves.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an air flow rate adjusting device for adjusting the amount of aeration air sent to an aeration tank in a sewage treatment plant.

The air volume of the aeration tank in the sewage treatment plant is regulated by controlling the number of blowers in operation and adjusting the opening of the suction valve.
The control system is shown in FIG.

In Figure 1, 1-1 to 1-N are blowers that suck in atmospheric air and supply it to the aeration tank, and 2-1 to 2-N are blowers 1 to 2-N.
Suction valves arranged on the suction side of -1 to l-N, 8-1 to 8
-N blowing orifice, 4-1 to 4-N are landscape converters, 5 is a filter, 6-1 to 6-N are each of the blowers 1-1 to 1-
A discharge motor-operated valve is installed on the discharge height 1 of H, 7 is an orifice inserted in the air discharge passage that branches off from the pipe to the Hatsue tank and communicates with the atmosphere, and 8 is pushed into the air discharge passage. 9 is an air flow converter, 10 is an indicator, 11 is an adder that adds up the output of each of the air volume converters 4-1 to 4-N that detects the suction N, and 2 is a sewage inflow. A ratio setter 13 uses the value of this setter 12 as a set value, and uses the output feedback value of the adder 11 as a set value for the suction valves 2-1 to 2-. PI that generates the valve opening adjustment signal of N
The D controller 14 is a blower number control device that controls the total number of blowers in operation according to the value of the setting device 12.

In this system, the entire discharge air volume of the blowers 1-1 to 1-H is controlled by adjusting the opening degrees of the suction valves 2-1 to 2-N, and the number of operating blowers is controlled according to the required air volume.

By the way, the discharge air volume of the blowers 1-1 to 1-N is the same as that of the suction valve 2.
It is difficult to widen the adjustment range only by adjusting the opening of -1 to 2-H, and normally the operable range on the lower limit side is 6.5% compared to 100% on the upper limit side. θ~70chi.

For this reason, there are the following drawbacks.

(1) An area where the air volume cannot be supplied occurs between when one blower is operated and when two blowers are operated.

For example, if the lower limit flow rate f for one unit is 70%, the air volume will be 70 to 100% when one unit is operated, and the air volume will be 140 to 200 x amount when two units are operated, making it impossible to supply an air volume of 100 to 140 x.

Similarly, discontinuities may occur between two-unit operation and three-unit operation. In other words, it becomes impossible to appropriately adjust the air volume.

(11) Sewage? At times when the number of people is very low or when the sewage treatment plant is initially constructed and a sufficient amount of sewage inflow has not yet been ensured, even one blower can generate too much air and cause overload. be.

The present invention has been made to eliminate the above-mentioned drawbacks, and the value obtained by subtracting the amount of air discharged is used as the foot check value of the PID controller. It is an object of the present invention to provide a vent air flow rate adjusting device which can continuously adjust the vent air flow rate with a simple configuration by providing an alarm setting device that closes the valve completely and opens it at the lower limit value.

Is this invention the following? A detailed explanation will be given based on the illustrated embodiment.

FIG. 2 shows one embodiment of the present invention, 1-1 to 1-
N is a blower, 2-1 to 2-N are suction valves, 3-1 to 3-N
is an orifice, 4-1 to 4-N are air volume converters, 5 is a filter, 6-1 to 6-N are discharge electric valves, 7 is an orifice,
8 is an air discharge valve, 9 is an air volume converter, 11 is an adder, 12 is a ratio setter, 13 is a PID controller, 14 is a blower number control device, 15 is the air volume converter from the output of the adder 11 Output of device 9? a subtractor 16 for subtracting the feedback value of the PIDvAI saving 13;
When the output of No. 3 is below the specified value L (the opening of the suction valve? A value that is so narrowed that the discharge air volume is adjusted below the lower limit), open the air discharge valve 8 and set it above the specified value H (>L). A': This is the ¥ information setting device that drives the 8 air discharge valves to close when .

That is, the air discharged from the air discharge valve 8 to the atmosphere is subtracted from the sum of the blower suction air G°C to obtain PI D 7. H, +4 feedback value of node weight 3 and -T, PIT) F, l
When the output of 1-section weighing weight 3 is below the specified value, lower limit death notice ThU
When the controller output recovers above the specified value, the alarm is canceled and the opening of the air blower valve 8 is maintained at that point, and the controller output returns to the specified value. This system is different from the conventional system in that 16 information setting devices are provided to issue a full upper limit alarm and close the air discharge valve 8 when H or higher occurs.

With such a configuration, the output of the controller 13 reaches the specified value H.
In the above case, the air volume is adjusted by controlling the number of units and adjusting the opening degrees of the suction valves 2-1 to 2-H, and when the adjustment output falls below the specified value, the exhaust alarm setting device 16 operates. Then, the air discharge valve 8 is opened by the output of the lower limit signal, and air is discharged. That is, overexertion is prevented. This air discharge continues even if the adjustment output recovers to the specified value or higher, if it is below the specified value I.

After this, when the control output becomes equal to or higher than the specified value H (a value that is slightly higher than the specified value), the blow-off valve 8 is closed by the upper limit alarm output, and as described above, the number of units is controlled and the valve opening degree is controlled. The adjustment adjusts the amount of airflow.

In the above operation, if the difference between H and the specified value of the setting device 16 is reduced, the total amount of air discharged to the atmosphere from the air discharge valve 8 will approach the minimum required, but the frequency of opening and closing of the air discharge valve 8 will increase, and the If the difference is increased, the total amount of wind (2) released into the atmosphere from the air discharge valve 8 will increase, but the frequency of opening and closing of the air discharge valve 8 will decrease.

Note that the blower valve 8 is normally provided to prevent sudden changes in discharge pressure during test run adjustment of the blowers 1-1 to 1-N and when the blower is started, and is not used for flow rate adjustment. If so, set an increment button on the output side of the alarm setting device 16. (Things that need to be operated) Take measures such as installing all of them or adjusting the specified value Hi amount. Is the set value input for the PID controller 13 you received a fixed ratio for sewage inflow? However, it is not limited to this value.

As described above, according to the present invention, in addition to the opening adjustment of the suction valve of the blower and the control of the number of blowers, the adjustment by the blower valve is provided as an auxiliary control means, so that the air volume can be continuously adjusted. This makes it possible to adjust the amount of sleepiness appropriately. In addition, since only a subtracter for calculating the foot drop value and an alarm setting device for driving the blow-off valve are provided, circuit borrowing is simple and manufacturing is possible at low cost.

In addition, existing ventilation valves can be used, and their characteristics and opening/closing operation lifespan are 11? It has the advantage that it does not have to be something different.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an example of a conventional air volume adjustment device, and FIG. i'2 is a block diagram showing an embodiment of the present invention. 1-1~1-N...Blower, 2-1~2-N...
・Suction valve, 7... Orifice, 8... Air discharge valve, 4-1 to 4-N and 9... Air volume converter, 11
...adder, 12...ratio setter, 13.
...PID controller, 14...Blower number control device!
? ”:s 15...Subtractor, 16...↑・
T phase stage regulator.

Claims (1)

[Claims] (1) A plurality of blowers that suck atmospheric air and supply it to the aeration tank, and a plurality of suction valves arranged on the suction side of each blower,
An adder that calculates the total suction amount Jt of each blower, a blower number control device that controls the number of blowers according to the amount of sewage inflow, and an air discharge path that communicates with the atmosphere from the pipe leading to the aeration tank. A set of air discharge valves, an air discharge volume detector for detecting the air discharge volume, a circular part, a subtracter for subtracting the detected air volume from the output of the adder, and a ratio value set according to the amount of sewage inflow, etc. , a PID controller that generates a valve opening adjustment signal for the suction valve using the output of the subtracter as a feedback value; and a PID controller that receives the output of the controller and closes the blowoff valve at an upper limit value and opens it at a lower limit value. Air flow control device equipped with an alarm setting device and an alarm setting device that operates according to the state.