JPH089054B2 - Make-up water control device in circulating water system - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a makeup water controller for a circulating water system, and more particularly to a makeup water controller for a circulating water system including a circulating cooling water system including a plurality of relay tanks and a wash water system, mainly in the steel industry. The present invention relates to a cooling water system in a vacuum degassing facility, a continuous casting facility, various rolling facilities, an ultrapure water cleaning closed system in the electronic component industry, and a control device for makeup water to the cleaning water system.

[0002]

2. Description of the Related Art Circulating water systems are widely used in various industries such as the steel industry, the electronic parts industry, and the chemical industry. In such a circulating water system, it is necessary to keep the amount of retained water constant, but outflow (discharge) of water to the outside of the system is unavoidable. Therefore, in order to keep the amount of retained water as constant as possible, make-up water is required. Supply is made.

The details will be described below by taking the case of a circulating water system in a rolling facility as shown in FIG. 1 as an example. In the circulating water system shown in FIG. 1, the cooling water is sent to the rolling equipment 1 via the scale pit 2, the sedimentation basin 3, the filter 4, the cooling tower 5 and the cold water tank 6, whereby the circulating cooling water system is formed. There is. Further, a backwash drainage tank 7 is connected to the filter 4, and a part of the water in the circulating water system is returned to the circulating cooling water system through the backwash drainage tank 7.

In this circulating water system, the scale pit 2
Since water is discharged from each facility, it is necessary to supply makeup water to keep the amount of water held constant. For example,
What is discharged is the water adhering to the scale discharged in the scale pit 2, the water content in the sludge of the sedimentation tank 3, the backwash drainage in the filter 4, the evaporation and scattered moisture in the cooling tower 5 (drift loss). Blow water and the like for preventing the concentration of the dissolved substance in water by evaporation. On the other hand, part of the water in the sludge and the treated water from the backwash drainage flow into the circulating water system. However, since the amount of discharged water is larger, the amount of retained water is prevented from decreasing with time and becoming inoperable unless supplementary water is supplied. Will be needed.

Conventionally, supply of makeup water in such a circulating water system is performed by the following method. That is, it is performed by a method of adjusting the amount of makeup water according to the water level (level) in the cold water tank 6 or a method of constantly supplying a predetermined amount of makeup water.

[0006]

However, in the above-mentioned conventional supply method of makeup water, there is a problem that it is basically difficult to keep the amount of retained water constant.
Particularly, in the case of a large amount of circulating water system of thousands to tens of thousands m ³ / Hr as used in the steel industry, various serious problems are caused. That is, in the case of a large amount of circulating water system, it is necessary to absorb a large amount of overflow in order to facilitate level control, the drainage facility becomes large and the operating cost increases, and the timing of replenishment is set to one drain tank. Since it is performed in (for example, the cold water tank 6), it tends to be excessively replenished, the replenishment water is wasted a lot, and the chemical cost is further increased when the chemical treatment is performed. Further, since it is necessary to protect a large-capacity pump motor, a large-capacity water tank having a long residence time is required due to switching hours, which causes problems such as high equipment cost.

The present invention has been made by paying attention to such a situation, and an object thereof is to solve the problems of the above-mentioned conventional ones and to make it necessary without requiring a large drainage facility or the like. Water supply in a circulating water system that can supply makeup water in proportion to the amount of stored water, keep the amount of water held, and reduce facility cost, operating cost, and water loss It is intended to provide a device.

[0008]

In order to achieve the above object, the present invention provides a makeup water control device in a circulating water system having the following configuration. That is, the makeup water control apparatus according to the present invention is a circulating cooling water system and a washing water system including a plurality of relay tanks in which a reference value of the amount of retained water is set and at least one of the inflow amount and the outflow amount of water is adjusted. In the recirculating water system, the replenishing water is supplied to the recirculating water system so that the amount of replenishment water can be adjusted, the holding water amount detecting means for detecting the respective holding water amount by providing a detecting section in each relay tank, and the holding water amount detection. Comparing the total sum of each held water amount detected by the means and the total sum of each held water reference amount, and comprising a supply water amount control means for controlling the water supply means to the supply water amount according to the difference. It is a makeup water control device in a characteristic circulating water system.

[0009]

As described above, the makeup water control device for the circulating water system according to the present invention is provided with the water replenishing means for supplying the makeup water to the circulating water system so that the amount of the makeup water can be adjusted, and the detecting portion provided in each relay tank of the circulating water system. The retained water amount detecting means for detecting each retained water amount is compared with the total sum of the retained water amounts detected by the retained water amount detecting means and the total sum of the retained water reference amounts, and the water supply means corresponding to the difference in the supplied water amount. And a supply water amount control means for controlling. Therefore, during operation of the circulating water system, the amount of reduction of the amount of retained water can be surely or always grasped by the retained water amount detecting means, and make-up water corresponding to the reduced amount is supplied from the water supply means by the supply water amount control means. obtain. Therefore, make-up water can be controlled so that the inflow amount and the outflow amount of water in each tank are balanced. Therefore, the amount of water held in the circulating water system can be kept constant and an excessive supply of make-up water can be avoided. .

Further, since the amount of water held in the circulating water system can be kept constant as described above, the water level of each tank can be simulated and the switching hour of the water pump of each tank can be quantified. Furthermore, overflow at the time of starting and stopping the operation can be avoided. Therefore, the water supply equipment and the like can be downsized, the equipment cost can be reduced, and the operation management can be facilitated to reduce the operation cost.

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

[0012]

DETAILED 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 facility 1, a scale pit 2,
The sedimentation tank 3, the filter 4, the cooling tower 5, and the cold water tank 6 are cyclically connected to each other.

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

After most of the coarse scale is precipitated and separated in the scale pit 2, the cooling water (treated water) is sent to the sedimentation tank 3 by the pump 10 to remove fine scale.
On the other hand, the coarse scale settled in the scale pit 2 goes out of the system with a club bucket or the like, and the water attached to the scale goes out of the system accordingly. Set the horizontal cross-sectional area of the tank of sedimentation pond 3 to A
2, and assuming that the water level detected by the water level detecting means 22 is L2, the amount of water held in the tank is A2 × L2.

The fine scale that has settled in the settling basin 3 is sent to the sludge thickener 8 by the sludge pump 14 and further sledge lagoon or dehydrator 9 by the pump 16.
The cake after being dehydrated is discharged, and the water discharged by the dehydrating action is sent back to the settling tank 3. On the other hand, settling pond 3
In order to remove finer scales, the water after the removal of finer scales was sent to the filter 4 via the pump 11 to be filtered, and then to the cooling tower 5 to be contacted with the atmosphere and cooled. After that, it flows into the cold water tank 6. At this time, water is discharged to the outside of the system due to evaporation and drift in the cooling tower 5. Further, the conductivity of water is measured in the cold water tank 6, and based on this result, a part of the filtered water 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 backwash water for the filter 4, and a fixed amount is discharged by the pump 13 and sent to the filter 4 in a fixed time. However, when the backwash conditions do not match, the time may change slightly. Assuming that the horizontal cross-sectional area of the cold water tank 6 is A3 and the water level detected by the water level detecting means 23 is L3, the amount of water held in the cold water tank 6 is
It will be A3 x L3.

The water that has been backwashed in the filter 4 flows into the backwash drain tank 7. Here, the horizontal cross-sectional area of the backwash drainage tank 7 is A
4, and assuming that the water level detected by the water level detecting means 24 is L4, the retained water amount is A4 × L4. A certain amount of backwash drainage from the backwash drainage tank 7 is pumped by the pump 15 to a sludge thickener 8
The very fine scale (1 to 50 μm) is completely processed by coagulation and sedimentation and is deposited on the bottom of the thickener 8. The scale from the settling tank 3 also flows into the thickener 8 and is deposited and deposited on the bottom. The water that has been scale-separated in the thickener 8 is sent again to the inlet of the settling tank 3 together with the desorbed water of the dehydrator 9.

In the circulating water system consisting of such a circulating cooling water system and a cleaning water system, the cooling water decreases due to evaporation in the rolling facility 1 to be cooled, evaporation or drift in the cooling tower 5, etc. It is necessary to supply makeup water while ensuring it. Therefore, the cold water tank 6 is connected to a water replenishing means realized by a replenishment water supply pipe 17 having a flow rate adjusting valve 25, and supplies replenishment water as described below.

That is, since the amount of water held in each tank is obtained by measuring as described above, the sum ΣQ of the amount of water held in the circulating water system is
ΣQ = A1 × L1 + A2 × L2 + A3 × L3 + A4 × L4 can be obtained, and the replenishing water is supplied by the water replenishing means so that ΣQ becomes a predetermined constant value. Then,
An ideal make-up water supply control system that balances the inflow and outflow of water in each tank.

Specifically, such control can be automatically performed 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 detecting means 19, a control means 20, an individual water level adjusting means 26, and a timer circuit 27, and the water level detecting means 21 to 24 are connected to the input port,
The motors of the pumps 10 to 15 and the drive unit of the flow rate control valve 25 are connected to the output port.

The operation of the processing unit 18 will be described below with reference to FIG. When the operation is started 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 the respective detecting means 21 to 24 are sent to the retained water amount detecting means 19. In the next step S3, the detecting means 19 determines the amount A1 of water held in each of the water tanks 2, 3, 6 and 7.
Detects × L1, A2 × L2, A3 × L3 and A4 × L4.

The individual water level adjustment in each tank is performed by the individual water level adjusting means 26 in the next step S4 in accordance with the value of each held water amount. Specifically, pump in scale pit 2.
10 is stopped at the water level L1, the water level L3 is set at the upper limit of 100% in the cold water tank 6, and an alarm is issued, and the backwash drainage pump 15 is stopped at the water level L4 in the backwash drainage tank 7.

Before and after this individual water level adjustment, step S5
In enters the operation of the control unit 20, first, calculates a fleet water [sum] Q, the process proceeds to step S6 to perform the comparison with the reference held water volume [sum] Q _0, the flow rate in step S7 if [sum] Q <[sum] Q ₀ The opening degree of the control valve 25 is controlled to supply makeup water to the cold water tank 6 at a valve opening degree corresponding to the value of ΣQ ₀ −ΣQ. Incidentally, it is practical that the control range of the amount of water held is set to a range of ± 2% in consideration of the error of the instrument, and the range is controlled by turning on / off the flow rate control valve 25.

As described above, an ideal makeup water supply amount control system in which the total amount of water held ΣQ is stable and the fluctuation of the water level in each water tank is small is realized.

[0025]

According to the makeup water control device in the circulating water system of the present invention, the decrease amount of the retained water can be grasped at any time or at all times, and the makeup water corresponding to the decrease amount can be supplied. Make-up water can be controlled so that the inflow and outflow of water in each tank are balanced, so that the amount of water held in the circulating water system can be kept constant and an excessive supply 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 hour of the water pump for each tank, and to avoid overflows at the start and stop of operation, thus making it possible to miniaturize water supply equipment, etc. Equipment cost can be reduced, operation management can be facilitated, and operation cost can be reduced. Moreover, since the amount of water held in each tank can be grasped and adjusted, the treatment in each tank can be safely performed without any trouble.

[Brief description 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 block diagram of a control circuit according to the embodiment of the present invention.

FIG. 3 is a flowchart diagram illustrating an operation of a processing unit 18 shown in FIG.

[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--Treatment part 19--Water holding amount detection means
20--Control means 21, 22, 23, 24--Water level detection means 25--
Flow control valve 26--individual water level control means
27--timer circuit

Claims (1)

[Claims] 1. A circulating water system including a circulating cooling water system and a wash water system, which includes a plurality of relay tanks in which a reference value of the retained water amount is set and at least one of an inflow amount and an outflow amount of water is adjusted, Water replenishing means for supplying water to the circulating water system so that the amount of water can be adjusted, holding water amount detecting means for detecting each holding water amount by providing a detection unit in each relay tank, and each holding water amount detected by this holding water amount detecting means And the sum total of the reference amount of each held water, and a supply water amount control means for controlling the water replenishing means to supply water amount according to the difference, and replenishment in the circulating water system characterized by the following: Water control device.