JP2921159B2 - Filtration Pond Control Method by Fuzzy Inference - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a filter control system for controlling a filter by a control device such as a process controller, and more particularly to a filter control system for realizing optimum control using fuzzy inference.

[0002]

2. Description of the Related Art Among various processes in a water purification plant, there is a filtration process as a process for removing small blocks and suspended matter which cannot be removed by a precipitation process, and it is possible to obtain highly purified treated water by removing suspended matter. it can. A sand filtration method is used as a filtration process for removing suspended substances having a relatively low concentration, and a filtration pond is used. A filtration pond separates and retains suspended matter contained in water at an appropriate speed by passing water through a layer filled with an inert filter medium. Since the speed cannot be maintained and the filtration ability is reduced, it is necessary to wash the filtration layer to avoid this.
The conventional filtration pond control method detects the instantaneous value of the head loss,
The filtering capability is determined only by the instantaneous value.

[0003]

However, in the above-mentioned conventional filter pond control method, the cleaning timing is controlled only by the instantaneous value of the head loss that is proportional to the filtering speed and the amount of suspended matter suppression. Since the capacity cannot be maximized and the capacity of the filtration ponds is not comprehensively determined, optimal control is difficult when considering the macro operation of a plurality of filtration ponds.

SUMMARY OF THE INVENTION The present invention has been made in view of such problems, and makes it possible to maximize the capacity of a filtration pond, optimize the macro operation of a plurality of filtration ponds, and improve the utilization rate of purified water. It is another object of the present invention to provide a filter control system with a flexible algorithm that realizes power saving and life extension.

[0005]

Means for solving the above problems in the present invention is to remove suspended substances in raw water by a plurality of filtration ponds and to wash the filtration ponds with purified water returned from the purification ponds. In the filter pond control method of the water purification plant system, the target value of the raw water flow is set by the first fuzzy inference based on the integrated flow rate of the raw water, the head loss of each filter pond, and the water level of the water purifier. The washing of the filter ponds is determined by the second fuzzy inference from the number of ponds and the water level of the water purification basin, and the number of filtration ponds of the required filtration step is determined by the third fuzzy inference from the water flow target value of the raw water and the water level of the clean water basin based on the raw water flow target. It is based on the filter pond control method.

[0006]

The present invention determines the raw water flow target value, determines the washing of the filtration pond, and evaluates the capacity of the filtration pond comprehensively based on the amount of the filtration process such as head loss, integrated flow rate of raw water, and water level of the purification tank. The number of filtration units is determined by fuzzy inference.
In the present invention, three stages of fuzzy inference are provided, and in the first fuzzy inference, the raw water flow target value is set based on the integrated flow of raw water, the loss head of each filtration pond and the water level of the clean water reservoir, and in the second fuzzy inference, The washing of the filtration pond is determined from the target raw water flow value, the number of filtration ponds during filtration, and the water level of the purification basin. In the third fuzzy inference, the filtration basin of the required filtration process is determined based on the target water flow target value and the water level of the purification basin. Determine the number.

[0007]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a configuration diagram of one embodiment of the present invention. In the figure, 1 is a first fuzzy inference (1), 2 is a second fuzzy inference (2), 3 is a third fuzzy inference (3),
Reference numeral 4 denotes a sedimentation pit, 5a to 5n denote a plurality of filtration ponds, and 6 denotes a water purification pond. In the figure, the solid line indicates the water system, and the water filtered from the sedimentation pit 4 via the raw water valves 7a to 7n and the flow meters 8a to 8n in the respective filtration ponds 5a to 5n is supplied to the water purification basin 6.
A part thereof is returned to the filtration ponds 5a to 5n by the washing pump 9 and used for washing them. In the present embodiment, as a filtration pond control method of such a system, the raw water flow rate detected by the flow meters 8a to 8n is calculated by an integrator 10.
The integrated flow rate of raw water, the head loss of each of the filtration ponds 5a to 5n, and the water level of the water purification tank 6 are input to the first fuzzy inference (1) to set a target value of the raw water flow rate. Via the controller 11, the raw water valves 7a to 7n are controlled. From the target value of the raw water flow rate, the number of filters during filtration, and the water level of the water purification tank 6, the second fuzzy inference (2) determines the cleaning of the filter pond and issues a filter pond cleaning command. The third fuzzy inference (3) determines the number of filtration ponds in a required filtration step from the target value of the raw water flow rate and the water level of the water purification basin 6, and issues a filtration basin filtration command.

Next, fuzzy inference of the embodiment will be described.
It is publicly known that fuzzy inference is established by a membership function and a rule matrix.

(1) In the first fuzzy inference, the membership function has three types of phenomena: loss head (LS), integrated raw water flow (FQ), and water level of the clean water reservoir (JL). There is a raw water flow rate target value (SQ), and three stages of L, M, and S are respectively set, and the rule matrix for them is as shown in the table below.

[0010]

[Table 1]

(2) In the second fuzzy inference, the membership function determines the raw water flow rate target value (S
Q), number of filtration ponds during filtration (NR) and water level of water purification tank (J
L) and the filter pond cleaning command (S
E), and three levels of L, M, and S are set, and the rule matrix for them is as shown in the table below.

[0012]

[Table 2]

(3) In the third fuzzy inference, the membership function defines the raw water flow target value (S
Q), there are two types of water purification tank water level (JL), and as a cause item there is a filtration tank filtration command (RK).
Three levels of M and S are set, and the rule matrix for them is as shown in the table below.

[0014]

[Table 3]

In this embodiment, each command to the filtration pond is determined by such three fuzzy inferences.

This embodiment has the following advantages.

(1) The capacity of the filtration pond can be maximized.

(2) The macro operation of a plurality of filtration ponds can be optimized.

(3) Since the number of times of cleaning a filtration pond using a large amount of purified water can be reduced, the utilization rate of purified water can be improved, the operation time of a cleaning pump and the like can be shortened, and power saving and life extension can be achieved.

(4) A filter cleaning command or the like is performed by fuzzy inference, a flexible algorithm can be configured, and its change and modification are easy.

[0021]

As described above, according to the present invention, the capacity of a filtration pond can be maximized, the macro operation of a plurality of filtration ponds can be optimized, and the filtration ponds using a large amount of purified water can be washed. Filtration control method by fuzzy inference that reduces the number of times to improve the utilization rate of purified water and shortens the operation time of the washing pump to save power and extend the life, configures a flexible algorithm, and easily changes and corrects it Can be provided.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an embodiment of the present invention.

[Explanation of symbols]

1,2,3 ... Fuzzy inference, 4 ... Settling pond pit, 5 ... Filter pond, 6 ... Water purifier, 7 ... Raw water valve, 8 ... Flow meter, 9 ... Wash pump, 10 ... Integrator, 11 ... PI controller .

Claims (1)

(57) [Claims] 1. A filter control system for a water purification plant system for removing suspended solids in raw water by a plurality of filtration ponds and cleaning the filtration ponds with purified water returned from the water purification basin. The raw water flow target value is set by the first fuzzy inference based on the head loss of the water and the water level of the water purification basin, and the target value of the raw water flow, the number of the filtration ponds being filtered, and the water level of the water purification basin are determined by the second fuzzy inference based on the raw water flow target value. A filter control method comprising: determining washing; and determining the number of filters in a required filtering process by a third fuzzy inference from the raw water flow rate target value and the water level of the purification tank.