JPS5886611A - Flow rate controlling method - Google Patents

Abstract

PURPOSE:To accurately realize a final command flow-rate integral value per day by deciding on the operation target of the remaining time from the difference between a command flow-rate integral value per day and a flow-rate integral value up to the present, and then controlling equipment to be controlled. CONSTITUTION:By a command (t) generated by a counting circuit 12 at every period Tc, a flow-rate integrating circuit 13 resets the last drawing-amount integral value Qp. By the command (t), an arithmetic circuit 15 performs arithmetic to find and supply a command drawing-amount value Qps per operation to a control circuit 16. The control circuit 16 selects a pump 2A and sends an operation command DA to start operation. Thus, the pump 1A is so controlled that the drawing-amount integral value Qp is equal to the command value Qps. When a daily command value Q or periodic set value Tc is varied in the middle of a day, calculation is carried out at successive drawing-period timing. This calculation formula decides on the command value Qps per operation which realizes the command value Q per day from an integral value QT up to a current day and the remaining time Tr even when the daily command value Q or drawing period Tc is varied.

Description

[Detailed Description of the Invention] (a) Description of the Technical Field The present invention provides for intermittent control of controlled machines such as pumps and valves.
The present invention relates to a flow rate control method that achieves a preset target flow rate value per unit time (for example, one day) by performing a ζ operation.

(b) Prior art a @ ii In general, raw sludge extraction from the first settling tank and excess sludge extraction from the final settling tank in a sewage treatment plant are carried out intermittently several times a day by setting a target amount of sludge to be drawn per day. In many cases, a method is used in which the pump is operated periodically to achieve the target sludge removal amount. The case where surplus sludge is extracted from the two surplus sludge pumps 4cJ:, 1, and the final settling tank will be described below.

Figure 1 shows an example process. Excess sludge in the final sedimentation stage 1 is drawn out by sludge pumps 2A and 2B, and sent to a thickening tank 4 through a flow meter 3 that measures the sludge flow rate.

For automatic control, sludge pump 2A.

2B is operated intermittently several times a day according to a drawing cycle timer in order to satisfy a predetermined daily target flow rate integrated value, that is, a target sludge drawing amount. in this case,
Normally, one sludge pump 2A, 2B is operated. A conventional control function in such a process will be explained.

That is, first, the target sludge removal amount Q per day is set from the water quality data, and the number of times of sludge removal per day is set. Then, the target value for one operation, that is, the target value for pulling out QpH, is determined by the following equation based on the pulling period (for each time To) determined from the number of times of pulling out Np.

Q,,L,,Pa(l) However, when NP=F stone ■4X6O P This drawing target value Qps is given to a pump control circuit (not shown). The pump control circuit controls two sludge pumps or 2B in order to achieve the above-mentioned drawing target value Φ. This control is performed as follows. That is, sludge pump 2
The sludge is pulled out by a person or 2B, and its flow rate is measured by a flow meter 3. So this sludge a
Input itcaw and integrate it. This integrated value Qp is configured so that it is set to zero in the drawing cycle mother (.Therefore, this integrated value ψ is the integrated value of one drawing amount. The integrated value Qv of the pulling amount is inputted, and this is compared with the target value Qps of the one-time pulling, and control is performed so that these agree with each other.

If the above control is expressed in a time chart, it will be as shown in Figure 2. In Figure 8, the horizontal axis represents the time battle, and the sludge pump is operated for a predetermined period of time at each regular period defined by time TO.

However, the following problems arise in the driving direction as described above. , o Both speeds, in the management of sewage treatment processes, the daily target sludge extraction amount Q is determined from water quality data. You can change the sludge extraction jtQ or cycle (time Ta), or change the pump stop period ξ between each extraction cycle in Figure 2.
In many cases, the pump is operated manually. In such a case, the conventional method cannot ultimately accurately achieve the target daily sludge removal amount Q. In other words, when the daily target sludge extraction amount Q or the cycle (time Tc) is changed, the above formula (1) is calculated at the extraction cycle timing closest to the time of the change, and the one-time extraction Saginome collar value QP8 is calculated. The pump is controlled based on the calculated value. However, since the above formula (1) does not take into account the amount drawn up to the point of change in one day, the 1
The target withdrawal amount QPII is the final daily target withdrawal amount Q
The resulting value will be inaccurate. For the same reason,
If the pump is operated manually during the stop period, the daily amount of sludge removed will be greater than the daily target sludge removal amount Q.

(C) Object of the Invention The object of the present invention is to calculate the final target flow rate integrated value per day for changes in the daily target m-lid integration during one shift and the withdrawal cycle and for manual operation of the pump. The object of the present invention is to provide a flow rate control method that accurately realizes the following.

(d) Structure of the Invention The structure of the present invention will be explained below with reference to an embodiment shown in FIG. Note that parts corresponding to those shown in FIG. 1 will be described with the same reference numerals. In the figure, 11 is an input/output interface circuit, which is interposed between the process side in the lower part of the figure and the control side by a microcomputer, etc. in the upper part. ! Input and output numbers. The signals handled here include the sludge flow mQW from the flow meter 3, the status signals Sm and 8B from each sludge pump 2A and 2B, and the operation signal 0m that controls the start and stop of these sludge pumps 2A and 2B. It is DB.

Reference numeral 12 denotes a drawing cycle timer count circuit, which generates a timing command t every time the time count value reaches a preset value l11C, that is, every time the drawing cycle begins.

13 is a one-time flow rate integration circuit, which inputs the sludge flow rate φ;
This is integrated and the integrated value is output. Furthermore, when the timing command 1 from the extraction period timer count circuit minor is input, the integration is stopped and reset at that point. Therefore, this integrated value ψ is the flow rate per one time, that is, the integrated value of the amount of extraction. 14 is a daily flow rate integration circuit which inputs the sludge flow rate Qw and calculates the flow rate integration value from the beginning of the day (for example, 0:00) to the current time, that is, the amount of sludge extracted. 15 is a calculation circuit for the amount of work per day, which calculates the amount of work per day 11if, which is manually set in advance or obtained from another calculation circuit number.
The i amount integrated value, that is, the target extraction amount Q, the set cycle To, the current sludge extraction amount QT, and the remaining time Tr of the day determined from the built-in counter, etc. is given, and the timing signal 1 is inputted. Each time, the operation target value per operation, that is, the pull-out amount target value Qps is calculated using the following formula.

QPI; Violet oak tree extraction per time Q: Target amount of extraction per day Np: Number of extractions possible during the remaining time of the day Np is rounded down to the nearest decimal point 11, NP>1.0 First of 9781 days Accumulated value of withdrawal amount Tr from to current time: Remaining time of the day (minutes) TO = withdrawal period timer setting value (minutes) 16 is a pump control circuit, and the above 11 operation filter calculation circuit 15
The target value QPIB for one extraction is output from the sludge pump 2A, 2B, and the status signal Sm*8" (sludge pump that can be automatically controlled depending on the operating status and failure condition m5 (in this case, two people and one person) ) and give a start command to it.Then, enter the sludge flow rate that is drawn out due to the operation of the two sludge pumps, that is, the integrated value Qp of the drawn amount for the previous 11 times, and this is the drawn am value per 11 g. Control two sludge pumps to match QPI.

(e) Effect of the invention In the above configuration, the extraction period timer count circuit 12
As shown in FIG. 2, is a preset constant period To
Output timing command/command t to @. In response to this timing command t, the '% one-time flow rate integration circuit 13 resets to zero the integrated value of the amount pulled out per one time, which has been integrated by the previous sludge drawing operation. In addition, by inputting the above-mentioned timing command type, the one-time drawing amount calculation circuit 15 executes the calculation according to the above-mentioned formula (2), obtains the one-time drawing amount target value Qps, and sends this to the pump control circuit 16. give. In the pump control circuit 16, when the target value Qps of the amount of extraction per operation is inputted, a self-controllable sludge pump, for example, two people, is selected.
A driving command D is given to this to start the sludge drawing operation.

Then, the two sludge pumps are controlled so that the flow rate of sludge pulled out by this drawing operation, that is, the integrated value ψ of the amount pulled out per time, matches the target value QPI of the amount pulled out per time.

Next, if the daily target withdrawal amount Q or the withdrawal cycle timer set value TO is changed during the day, the calculation of equation (2) is performed at the next withdrawal cycle timing. Here, since equation (2) takes into account the withdrawal i accumulation value QT up to the current time in the day and the remaining time Tr of the day, it is necessary to change the target withdrawal amount Q per day or the withdrawal period timer setting value Tc. It is possible to determine the target value Qps of the amount of extraction per operation, which ultimately allows the target amount of extraction Q per day to be achieved. In addition, even if the sludge pump is manually operated by two people or 2B"Q in the middle, the target value Qps of the amount pulled out per operation is calculated by subtracting the amount pulled out due to manual operation at the next drawing cycle timing. It is possible to accurately achieve the target pulling amount Q per day for the final chrysanthemum.

(f) Other Embodiments Instead of using the extraction cycle timer 12, several extraction times per day may be set in advance, and intermittent extraction may be performed when the extraction times arrive; in that case (2) It can be implemented in exactly the same way by subtracting Np in the formula by 1 each time a pulling operation is performed from the set number of pulling times. Further, although the control function shown in FIG. 3 is a bird's-eye representation of the control function of a microcomputer, it is of course possible to construct the control function using actual hardware having such a function.

-) Overall i effect According to the present invention, even if there is manual intervention such as changing the daily target flow rate integrated value and the drawing period timer setting value or manual operation of the pump, the final -ζ daily target There are advantages in that a flow rate integrated value can be accurately achieved and a control device with good operability and controllability can be obtained.

[Brief explanation of drawings]

Fig. 1 is a diagram showing an example of equipment to which the present invention is applied, Fig. 2 is a time chart explaining general intermittent drawing, and Fig. 3 is a control block showing an embodiment of the flow rate control method according to the present invention-ζ. It is a diagram. 1: Sedimentation tank, 2A, 2B: Controlled machine 3 = flow rate needle, 4: Condenser tank 11: Input/output interface (b) path 13: 1-time flow rate integration circuit, 16: Pump control circuit 15: 1-time operation Quantity calculation circuit, 12: Drawing cycle timer count circuit, 14: Daily flow rate integration circuit, Qw: ff Volume Q: Target flow rate integrated value for one day, TO = Drawing cycle timer setting value, QP: 11 Operation target QP: Accumulated flow rate per time, QT: Accumulated flow rate per day. (7317) Substitute ff 1 person dialect ll± ats near f
il (4t; Figure 1゛21! I Figure 3

Claims (1)

[Claims] To achieve the daily target flow rate cumulative value Q by intermittently operating the controlled machine, the value obtained by subtracting the daily flow rate cumulative value QT from the daily target flow rate cumulative value Q above. is divided by the number of operations that can be performed/performed using the remaining time of IB to obtain the current target value of operation per operation Q.
A flow rate control method characterized by determining a target value QPI and controlling a controlled machine to achieve this target value QPI.