JPH04361821A - Replenishing water controller for circulating water system - Google Patents

Abstract

PURPOSE:To reduce equipment cost by controlling water supply quantity in accordance with the difference between a total holding water quantity which is detected in each relay tank in a circulating system and a total reference quantity of each holding water. CONSTITUTION:In the circulating water system containing plural relay tanks, the total of each holding water quantity, which is detected by the detecting means 21-24 of the holding water quantity in each relay tank, and the total of each holding water reference quantity are compared; and water replenishing means 17, 25 are controlled by a water supply control means at a water supply quantity corresponding to the difference. Thus, the decrease of the holding water quantity in the circulating water system is constantly and surely grasped, simultaneously the holding water quantity in the circulating water system is held at a constant level, and the reduction in the equipment cost is attained.

Description

[Detailed description of the invention]

0001

[Field of Industrial Application] The present invention relates to a make-up water control device in a circulating water system, and more particularly, to a make-up water control device in a circulating water system consisting of a circulating cooling water system including a plurality of relay tanks and a washing water system, and is mainly used in the steel industry. The present invention relates to a control device for supplying water to cooling water systems and cleaning water systems in vacuum degassing equipment, continuous casting equipment, various rolling equipment, or ultrapure water cleaning closed systems in the electronic parts industry.

0002

BACKGROUND OF THE INVENTION Circulating water systems are widely used in various industries such as the above-mentioned steel industry, electronic parts industry, and chemical industry. In such a circulating water system, it is necessary to maintain a constant amount of retained water, but the outflow (discharge) of water to the outside of the system is unavoidable. Supply is made.

[0003] The details will be explained below, taking as an example the case of a circulating water system in a rolling equipment as shown in FIG. In the circulating water system shown in Fig. 1, cooling water is sent to the rolling equipment 1 via the scale pit 2, sedimentation tank 3, filter 4, cooling tower 5, and cold water tank 6, thereby forming a circulating cooling water system. There is. Further, a backwash drainage tank 7 is connected to the filter 4, and part of the water in the circulating water system is returned to the circulating cooling water system via the backwash drainage tank 7.

[0004] In this circulating water system, scale pit 2
Since water is discharged from each facility, it is necessary to supply make-up water to maintain a constant amount of water. for example,
What is discharged is water adhered to the scale discharged from the scale pit 2, water in the waste sludge from the sedimentation tank 3, backwash water from the filter 4, and evaporation and scattered water from the cooling tower 5 (drift loss). , blow water for preventing concentration of components of a dissolved substance in water due to evaporation, and the like. On the other hand, part of the water in the waste sludge and treated water from backwash wastewater flow into the circulating water system. However, since the amount of water discharged is larger, it is necessary to supply makeup water in order to prevent the amount of retained water from decreasing over time and becoming unable to operate if makeup water is not supplied, and to keep the concentration level of the circulation system constant. It becomes necessary.

[0005] Conventionally, supply of make-up water in such a circulating water system has been carried out by the following method. That is, this is carried out by adjusting the amount of make-up water depending on the water level in the cold water tank 6, or by constantly supplying a predetermined amount of make-up water.

[0006]

However, the conventional make-up water supply method has a problem in that it is basically not easy to maintain a constant amount of water.
In particular, various serious problems arise in the case of a large-volume circulating water system of several thousand to several tens of thousands of cubic meters per hour, such as those used in the steel industry. In other words, in the case of a large-volume circulating water system, it is necessary to absorb a large amount of overflow to facilitate level control, which increases the size of the drainage equipment and increases operating costs. (For example, cold water tank 6) tends to lead to oversupply.
There is a lot of wastage of make-up water, and when chemical treatment is used, the cost of chemicals further increases. Furthermore, in order to protect the large-capacity pump motor, a large-capacity water tank with a long residence time is required due to switching hours, resulting in problems such as high equipment costs.

[0007] The present invention has been made in view of these circumstances, and its purpose is to solve the problems of the above-mentioned conventional methods and to eliminate the need for large-scale drainage equipment. Make-up water control in a circulating water system that can supply make-up water commensurate with the amount of water being used, maintain a constant amount of water, and reduce equipment costs, operating costs, and water loss. The aim is to provide equipment.

[0008]

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a make-up water control device for a circulating water system having the following configuration. That is, the make-up water control device according to the present invention includes a circulating cooling water system and a cleaning water system including a plurality of relay tanks in which a reference value of the amount of water held is determined and at least one of the inflow and outflow of water is adjusted. A water replenishment means for supplying make-up water to the circulating water system in a manner that allows the amount of water to be adjusted; a water amount detection means for detecting the amount of water held in each relay tank by providing a detection unit in each relay tank; A supply water amount control means that compares the total amount of each retained water amount detected by the means with the total amount of each retained water reference amount and controls the water supply amount according to the difference. This is a make-up water control device in a circulating water system.

[0009]

[Operation] As described above, the make-up water control device for a circulating water system according to the present invention includes a water replenishing means for supplying make-up water to the circulating water system in an adjustable amount, and a detection unit provided in each relay tank of the circulating water system. A retained water amount detection means detects each retained water amount, and the water replenishment means compares the sum of each retained water amount detected by this retained water amount detection means with the total of each retained water reference amount, and adjusts the supplied water amount according to the difference. and a supply water amount control means for controlling the amount of water supplied. Therefore, during the operation of the circulating water system, the amount of decrease in the amount of retained water can be reliably grasped at any time or all the time by the above-mentioned retained water amount detection means, and the supply water amount control means can supply make-up water commensurate with the decreased amount from the water replenishment means. obtain. Therefore, it is possible to control make-up water so that the inflow and outflow of water in each tank are balanced, and therefore, the amount of water held in the circulating water system can be maintained constant, and oversupply of make-up water can be avoided. .

Furthermore, since the amount of water held in the circulating water system can be held constant as described above, it is possible to simulate the water level in each tank, and it is also possible to quantify the switching hours of the water pumps in each tank. Furthermore, overflow can be avoided at the time of starting and stopping the operation. Therefore, the water supply equipment etc. can be downsized, equipment costs can be reduced, and operation management can be facilitated, leading to reductions in operating costs.

Moreover, since the amount of water held in each tank can be grasped and adjusted, the treatment in each tank can be carried out safely without any trouble.

0012

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows a block diagram of a circulating water system for cooling rolling equipment according to an embodiment. In this circulating water system, the circulating cooling water system includes a cooling water passage of the rolling equipment 1, a scale pit 2,
It is formed by cyclically connecting a sedimentation tank 3, a filter 4, a cooling tower 5, and a cold water tank 6.

In the circulating cooling water system, the rolls of the rolling equipment 1 are cooled by cooling water sent from the cold water tank 6 by the pump 12. This cooling water increases in temperature due to heat exchange with the rolls, contains scale generated during rolling, and flows into the scale pit 2. Here, the horizontal cross-sectional area of the scale pit 2 is A1, and the water level detection means 21
Assuming that the water level detected by is L1, the amount of water held in the scale pit 2 is A1×L1.

After most of the coarse scale has been separated by sedimentation in the scale pit 2, the cooling water (treated water) is sent to the settling tank 3 by a pump 10 to remove fine scale. On the other hand, the coarse scale precipitated in the scale pit 2 is discharged from the system by a club bucket or the like, and the scale-attached water is accordingly discharged from the system. The horizontal cross-sectional area of the sedimentation tank 3 is A
2. Also, the water level detected by the water level detection means 22 is set to L2.
Then, the amount of water held in the tank is A2×L2.

Fine scale precipitated in the sedimentation tank 3 is sent to the sludge thickener 8 by the sludge pump 14, and further sent to the sledge lagoon or dewatering machine 9 by the pump 16, and the cake after dewatering is discharged and dehydrated by the dewatering action. The discharged water is sent back to the settling tank 3 again. On the other hand, the water after fine scale removal in the sedimentation tank 3 is sent to the filter 4 via the pump 11 to be filtered in order to further remove fine scale, and then sent to the cooling tower 5 where it comes into contact with the atmosphere. After being cooled, it flows into the cold water tank 6. At this time, in the cooling tower 5, water is discharged to the outside of the system due to evaporation and drift. Further, the conductivity of the water is measured in the cold water tank 6, and based on this result, a portion of the water after filtration is discharged as blow water in order to keep the concentration constant.

A part of the water in the cold water tank 6 is used as water for backwashing the filter 4, and a certain amount is discharged by the pump 13 at a certain time and sent to the filter 4. However, the time may vary slightly if the backwash conditions do not match. Here, the horizontal cross-sectional area of the cold water tank 6 is A3, and the water level detection means 2
If the water level detected in step 3 is L3, the amount of water held in the cold water tank 6 is A3×L3.

The water after backwashing in the filter 4 flows into a backwash drainage tank 7. Here, the horizontal cross-sectional area of the backwash drainage tank 7 is A
4. Also, the water level detected by the water level detection means 24 is
Then, the amount of water held is A4 x L4. Backwash drainage tank 7
A certain amount of the backwash wastewater is sent to the sludge thickener 8 by a pump 15, where it coagulates and settles, completely treating very fine scales (1 to 50 μm).
It is deposited on the bottom of the thickener 8. The scale from the sedimentation tank 3 also flows into the thickener 8 and is deposited at the bottom. The scale-separated water in the thickener 8 is sent again to the inlet of the sedimentation tank 3 together with the dehydrated water from the dehydrator 9.

In such a circulating water system consisting of a circulating cooling water system and a washing water system, the amount of cooling water decreases due to evaporation in the rolling equipment 1 to be cooled, evaporation or drift in the cooling tower 5, and so the blow water is It is necessary to secure the supply of make-up water. Therefore, a water replenishment means realized by a make-up water supply pipe 17 having a flow rate regulating valve 25 interposed therein is connected to the cold water tank 6, and supplies make-up water as described below.

That is, since the amount of water held in each tank is determined by measurement as described above, the total amount of water held in the circulating water system ΣQ is
ΣQ=A1×L1+A2×L2+A3×L3+A4×L
4, and supplementary water is supplied by the water replenishing means so that ΣQ becomes a predetermined constant value. This results in an ideal make-up water supply amount control system in which the inflow and outflow amounts of water in each tank are balanced.

Specifically, such control can be performed automatically by using the following control circuit. That is, FIG. 2 is a control circuit block diagram according to the embodiment,
The processing unit 18 is provided with a retained water amount detection means 19, a control means 20, an individual water level adjustment means 26, and a timer circuit 27, and the input port is provided with water level detection means 21 to 24.
is connected, and each pump 10 is connected to the output port.
-15 motors and a drive unit for the flow rate control valve 25 are connected.

The operation of this processing section 18 will be explained below with reference to FIG. When the operation starts in step S1,
The process moves to step S2 based on the clock pulse signal from the timer circuit 27, and the water level signals from each of the detection means 21 to 24 are sent to the retained water amount detection means 19. The detection means 19 detects each water tank 2, 3, 6 in the next step S3.
and the amount of water held in 7 A1 x L1, A2 x L2, A3 x L3
and detect A4×L4.

In accordance with the value of each retained water amount, the individual water level in each tank is adjusted in the next step S4 by the individual water level adjusting means 26.
It is done by. Specifically, in the scale pit 2, the pump 10 is stopped at the water level L1, in the cold water tank 6, measures are taken such as issuing an alarm with the water level L3 as the upper limit level of 100%, and in the backwash drainage tank 7, the backwash drainage is stopped. pump 15 to water level L4
Stop at.

[0023]Sequentially to this individual water level adjustment, step S
5, the control means 20 starts operating, and first, the total retained water amount ΣQ
is calculated, and the process moves to the next step S6 to calculate the standard retained water amount Σ
A comparison is made with Q0, and if ΣQ<ΣQ0, the opening degree of the flow rate control valve 25 is controlled in step S7, and ΣQ0-
Makeup water is supplied to the cold water tank 6 at a valve opening degree according to the value of ΣQ. In addition, the control range of the amount of water held is ±2 considering the error of the meter.
% range, and it is practical to control the flow rate within this range by turning on/off the flow control valve 25.

[0024] As described above, an ideal make-up water supply amount control system is realized in which the total amount of retained water ΣQ is stabilized and water level fluctuations in individual water tanks are small.

[0025]

Effects of the Invention According to the make-up water control device for a circulating water system according to the present invention, the amount of decrease in the amount of retained water can be reliably grasped at any time or all the time, and make-up water commensurate with the amount of decrease can be supplied. Make-up water can be controlled so that the inflow and outflow of water in each tank are balanced. Therefore, the amount of water held in the circulating water system can be maintained constant, and oversupply of make-up water can be avoided. Become. In addition, since the water level of each tank can be simulated, it is possible to quantify the switching hours of each tank water pump, and furthermore, it is possible to avoid overflow at the start and stop of operation, and therefore it is possible to downsize water supply equipment, etc. This makes it possible to reduce equipment costs, and also facilitates operation management, thereby reducing operating costs. Furthermore, since the amount of water held in each tank can be grasped and adjusted, processing in each tank can be carried out safely without any problems.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing a circulating water system for cooling rolling equipment according to an embodiment of the present invention.

FIG. 2 is a control circuit block diagram according to an embodiment of the present invention.

FIG. 3 is a flowchart illustrating the operation of the processing unit 18 shown in FIG. 2.

[Explanation of symbols]

1--Rolling equipment 2--Scale pit 3--Sedimentation tank 4--Filter 5--Cooling tower 6--Cold water tank 7--Backwash drain tank 8--Sludge thickener 9--Dehydrator 10, 11 , 12, 13, 14, 15, 16--Pump 17--Makeup water supply pipe 18--Processing section 19--
Retained water amount detection means 20--Control means 21, 22, 23, 24--Water level detection means
25--Flow rate control valve 26--Individual water level control means
27--Timer circuit

Claims (1)

[Claims] Claim 1: In a circulating water system consisting of a circulating cooling water system and a washing water system including a plurality of relay tanks in which a reference value for the amount of water held is determined and at least one of the inflow and outflow of water is adjusted, Water replenishment means for supplying water to the circulating water system in an adjustable amount; water quantity detection means for detecting each quantity of water in which each relay tank is provided with a detection unit; and each quantity of water detected by the quantity of water detected by the water quantity detection means. Replenishment in a circulating water system characterized by comprising: a supply water amount control means that compares the sum of the total amount of water with the total of each water reference amount and controls the water supply amount according to the difference. Water control device.