JPH0752361B2 - How to determine the operation schedule of the water intake pump of the water purification facility - Google Patents

Description

[Technical Field to which the Invention belongs] [Technical Field of the Invention] The present invention temporarily stores water treated in a water purification facility in a water purification pond in which a fluctuation pattern of the outflow amount of water is known, and then a consumer In order to ensure that the fluctuation of the water level of the water purification pond falls within the allowable range of the water level when supplying the water to the water treatment plant, the temporal change in the discharge amount of the intake pump that supplies water to the water purification facility is determined in advance over a certain operation schedule period. It relates to a method for determining the operation schedule of the intake pump of the water purification facility.

[Prior art and its problems]

FIG. 1 is an explanatory diagram showing an example of facilities of a water purification plant. In the figure, raw water flows into a water intake well 2 from a water source river 1, is sent to a water purification facility 4 by an intake pump 3, and is treated.
The water purification facility 4 includes a stirring basin for injecting and mixing the raw water containing a coagulant for promoting the precipitation effect, a floc formation basin for forming flocs according to the result, and a precipitation for precipitating the formed flocs. It is a generally known one composed of a pond and the like. The water treated in the water purification facility 4 is temporarily stored in the water purification pond 5 and is supplied from here to customers by a water transmission / distribution pump, a water distribution pipe network, and the like (not shown).

FIG. 1A is a graph showing the time variation 6 of the outflow amount q _o from the water purification pond 5.

In such facilities, the outflow rate q _o (t) from the water purification pond (see Fig. 1A 6) fluctuates due to daily fluctuations in water demand, and the water source river 1 changes depending on the weather and season. There are also fluctuations in the inflow to the intake well 2. In order to supply water to consumers without excess or deficiency while adapting to such fluctuations, the intake well 2
Ordinarily, the number of operating intake pumps 3 and the intake flow rate are adjusted in accordance with the value of the water level in the water purification pond 5.

In this case, if the water intake pump 3 is frequently operated, consumption of the pump and accessories will be accelerated. In addition, when the pump operation amount per time is increased, the fluctuation of the inflow amount into the water purification facility becomes large, and it is necessary to change the amount of the coagulant injected into the raw water and the precipitation time variously according to the fluctuation amount. As a result, the quality of treated water may deteriorate.

Therefore, in the operation of such a facility, the number of times the pump is operated and the amount of operation per operation are kept as small as possible, while maintaining the water levels of the various ponds within the prescribed operating range (level range) without any excess or deficiency. It is required to supply water to the.

However, in the prior art, keeping the operating state of the pump as constant as possible is hardly considered. As shown in FIG. 2, this is within the operable range 11 of the pump.
The time t at which the pump is operated and the set value q at the time t
This is because there are infinitely many variations of the pump intake water fluctuation curve (operating schedule) 10, and it is practically impossible to select the optimum one.

In addition, the "dynamic" programming method (DP method) has been used to find the "optimal" operating schedule that minimizes the number of operations, but this method covers the entire operable range of the pump. Since the predictive calculation and evaluation are performed, the schedule that gives a large amount of operation in one operation is determined to be optimal, which causes a problem that a large flow rate fluctuation cannot be avoided. There is also a problem in that the storage capacity required for it also increases. For this reason, the above-mentioned DP method is difficult to apply to actual online control.

[Object of the Invention]

An object of the present invention is to solve the problems in the prior art as described above, and to reduce the number of operations of the pump and the operation amount per operation as compared with the conventional method, thereby reducing the fluctuation of the inflow amount to the water purification facility. The purpose of the present invention is to provide a method for determining the operation schedule of the intake pump that does not deteriorate the quality of treated water.

[Principle of Invention]

 Next, the principle of the present invention will be described with reference to the drawings.

FIG. 3 is an explanatory view newly showing a part of the facility shown in FIG. 1, and FIG. 3A is a graph showing a temporal change of the outflow amount from the pond 5 in FIG.

In these figures, the ground 5 is assumed to be located on the discharge side of the pump 3, but the water level of this pond 5 is required to be within the range of upper limit PH and lower limit PL (operating range), and Fluctuations in outflow from No. 5 q _o (t) (Fig. 3A 6)
Is given in advance. This is a necessary condition for determining a reasonable operating schedule according to the invention.

Figure 4 shows the operating schedule of the pump 20 {q (t _i ) i = 0,
1,2, ..., N} is within a finite time range T (N × Δt),
It is shown that a fixed value q ₁ , q ₂ , ..., q _n is taken within the range 11 of the driving ability at a constant time interval Δt, and the number of driving schedules that can be taken from this is finite. , The upper limit of the number of calculations for determining the desired driving schedule is determined. In this operation schedule, the change amount (| q (t _i ) − (t _{i + 1} ) |) of the discharge amount of the pump must be within a certain range dq. As a result, fluctuations in the flow rate during one pump operation are suppressed, and the amount of calculation required to obtain the desired operating schedule is reduced.

Fig. 5 shows the accumulated operation amount 30 {Sq (t)}, which is obtained by integrating the operation amount of the pump over time, and the total operation amount is calculated by obtaining the operation schedule that minimizes this value. Throughout the period T, the number of operations of the pump and the amount of operation per operation can be suppressed within certain limits, and the pump can be operated so that fluctuations in the flow rate are reduced.

The above is the explanation of the principle of the present invention.

Example of Invention

 Next, an embodiment of the present invention will be described with reference to the drawings.

FIG. 6 is a flow chart showing the procedure when the present invention is carried out in the facility shown in FIG. Reference is made to FIG.

In step, if the schedule period is 24 hours a day, it is set as 24 hours, and the fluctuation pattern of the outflow from the water purification tank 5 over 24 hours in step {q _o (t _i ) i = 0,1, …… 24}
Is given as the change (transition) of the flow rate value per unit time, and the water level of the water purification reservoir 5 during this time is the upper limit {PH (t _i ) i = 0 to 2
4}, and the lower limit {PL (t _i ) i = 0 to 24} is used.

Moreover, since a sufficient amount of water always flows into the intake well 2 from the water source river 1, no particular condition is set in this respect. Next, in step, the discharge amount of the pump 3 is set to three kinds of q ₁ , q ₂ , and q ₃ (however, q ₁ <q ₂ <q ₃ , Here, if the pump 3 has a constant speed, the discharge flow rate is naturally determined depending on the number of operating pumps. If the pump 3 has a variable speed, the discharge flow rate can be continuously changed by the combination of the number of operating units and the number of rotations, but the value is limited to the above three types.

Next, in step, the operation interval of the pump is every 1 hour, then in step, the operation amount dq of the pump once is set to dq <
The relational expression q ₃ −q ₁ is established, and q ₁ to q ₃ or
q ₃ prohibits significantly changing the flow rate to q ₁ from.

Next, in step, as the initial water level of the pond 5, the water level L (t ₀ ) at time t ₀ is arbitrarily set so that PL (t ₀ ) <L (t ₀ ) <PH (t ₀ ), and the pump is set. The discharge amount of 3 is q
Let (t ₀ ) = q ₁ . If there is an online input from the process, L (t ₀ ) = L, q using the online value.
(T ₀ ) = q may be set.

In the steps to, a loop for checking the operation schedule is formed while temporarily changing the pump discharge rate q (t ₁ ) from time t ₀ to t ₁ to q ₁ , q ₂ , and q ₃ , but at the step | q
The case where (t ₁ ) −q (t ₀ ) |> dq is excluded as no (N).

In step, the water level L (t ₁ ) at time t ₁ = t ₀ + Δt
Is calculated by the following formula.

(However, S is the bottom area of the pond.) In step, the water level L (t ₁ ) of the pond is PL (t ₁ ) <L (t ₁ ) <
It is judged whether or not the water level condition of PH (t ₁ ) is satisfied, and if not, such a driving schedule is excluded because it is not a valid driving schedule.

In the step, for the next iteration operation, t _E = t ₁ is set separately in order to clearly show that the examination is performed until time t ₁ , and L (t), q (t) is temporarily stored in the memory together with this time t _E.

In the step, it is judged whether or not all of q (t ₁ ) = q ₁ , q ₂ , q ₃ have been examined, and in the case of no, the process returns to the step and the same processing as described above is carried out. Goes to step.

In step, it is determined whether the driving schedule stored in step is determined until time t ₂₄ ,
If any not determined until time t _24, to it to read from the memory one of them in step, the water level in connexion time t _E returns to step initial water level, the pump at the time t _E discharge amount of initial After the step of pump operation, the same processing as described above is repeated.

If it is found in step that all reasonable driving schedules are required until time t ₂₄ , go to step, read all of these schedules from memory, and in step, calculate the cumulative manipulated variable Sq for each of the following. Calculated by formula.

At the step, the minimum value of the cumulative manipulated variables obtained at the step is obtained, and the driving schedule corresponding to the minimum value is uniquely obtained.

If the above procedure is programmed in the computer, this program is started at a fixed cycle of 1 hour, the operation schedule for 24 hours is always determined, and the pump is operated online based on this result, the flow rate becomes stable. The operation can be continued. The present invention can be similarly applied to a facility that performs intermittent operation.

FIG. 7 is a flow chart showing an embodiment obtained by partially modifying the embodiment of FIG.

In FIG. 7, steps ˜ are the same as those in FIG. 6, but the one with the smallest cumulative operation amount remains in the processing thereafter, and the processing of steps ,, in FIG. In the embodiment shown in FIG. 7, the area for storing the progress of the driving schedule is also saved.

In other words, this means that for other driving schedules, the cumulative manipulation quantity Sq ′ up to the middle of the schedule period is the driving schedule for which the minimum cumulative manipulation amount Sqmin is obtained.
The focus is on not becoming smaller than this Sqmin, and the cumulative manipulated variable Sq of the driving schedule obtained over the entire schedule period and the cumulative manipulated variable Sq ′ of the driving schedule obtained halfway are compared to Sq. It is a method of excluding those for which ′> Sq, and finally leaving a driving schedule with a cumulative manipulated variable of Sqmin.

In the step shown in FIG. 7, a large value that is not possible actually is set as the initial value of Sqmin. At the step, Sq ′ is compared with Sqmin, and if Sq ′ ≧ Sqmin, the operation schedule is excluded and the operation proceeds to step Sq ′.
<If Sqmin is reached, the step determines whether the schedule has been determined during the entire schedule period. If it is determined to the end, this driving schedule is stored in step, Sqmin is updated in step, and then the step is determined. Used as a reference.

When all the driving schedules have been checked at the step, if the procedure goes to the step and the driving schedule memorized at the step is read out, this is uniquely determined as the one having the minimum accumulated operation amount.

〔The invention's effect〕

According to the present invention, by limiting the time when the pump is operated and the operating state of the pump, it becomes possible to obtain the operating schedule of the pump by a finite number of calculations, and from this, the operating frequency of the pump is constant. It becomes the following. Also,
By reducing the frequency of operations and defining the range of increase / decrease amount per time, it is possible to reduce the fluctuation of the inflow to the water purification facility and stabilize the treatment in the water purification facility, which leads to deterioration of the quality of treated water. There is an advantage that there is no.

[Brief description of drawings]

Fig. 1 is an explanatory diagram showing an example of the facility of the water purification plant, Fig. 1A is a graph showing the temporal variation of the outflow from the water purification pond 5 in Fig. 1, and Fig. 2 is the variation curve of the water intake of the pump. A graph showing an example, FIG. 3 is an explanatory diagram newly showing a part of the facility shown in FIG. 1, and FIG. 3A is a pond 5 in FIG.
4 is a graph showing the temporal change of the outflow amount from the pump, FIG. 4 is a graph showing the operation schedule of the pump, FIG. 5 is a graph showing the cumulative operation amount of the pump, and FIG. 6 is a flow showing an embodiment of the present invention. FIG. 7 is a flow chart showing another embodiment of the present invention. Explanation of code 1 …… Water source river, 2 …… Intake well, 3 …… Intake pump, 4
…… Water purification facility, 5 …… Water purification basin, 6 …… Time variation of outflow from water purification basin 5, 10 …… Variation curve of pump water intake,
11 …… Pump operation range, 20 …… Pump operation schedule, 21 …… Pump operation amount range per operation, 30…
... cumulative amount of pump operation,

Continuation of the front page (56) Reference JP-A-48-35285 (JP, A) JP-A-51-129901 (JP, A) JP-A-52-20402 (JP, A) JP-A-52-78102 (JP , A) JP 52-88801 (JP, A) JP 53-38884 (JP, A) JP 53-125588 (JP, A) JP 53-143002 (JP, A) JP 54-90601 (JP, A) JP-A-55-112612 (JP, A) JP-A-55-143603 (JP, A) JP-A-56-16207 (JP, A) JP-A-56-83586 (JP, A) JP-A-58-117373 (JP, A) JP-A-58-223805 (JP, A) JP-A-54-62472 (JP, A)

Claims (1)

[Claims] 1. When the water treated in the water purification facility is temporarily stored in a water purification reservoir where the variation pattern of the outflow amount is known and then supplied to the customer, the fluctuation of the water level in the water purification reservoir causes the water level to change. It is a method for determining the operation schedule of the intake pump of the water purification facility that predetermines the temporal transition of the discharge amount of the intake pump that supplies water to the water purification facility over a certain operation schedule period so that it falls within the allowable range of Therefore, the amount of water that can be taken as the discharge amount of the intake pump is limited to a limited number, and the minimum unit of time that the pump discharge amount must maintain a fixed amount is set. Under the condition that the limit of the increase / decrease amount per hit is set, the operation schedule as the temporal change of the discharge amount of the water intake pump is determined by one or more sets as many as possible sets. And increasing / decreasing the discharge amount of the water intake pump from the plurality of sets of operation schedules, selecting the smallest accumulated operation amount over the schedule period, and determining the operation schedule of the water intake pump of the water purification facility. Method.