JP2018146224A - Cooling tower system - Google Patents

Abstract

A cooling tower system that can reduce blow water and make-up water and that can be easily controlled. When the operation of circulating and supplying cold water from the cooling tower 1 to the heat exchanger 4 is continued, the water level in the pit 1d gradually decreases and the electrical conductivity gradually increases. When the electrical conductivity rises to the intermediate value C1, the circulation pump 10 starts operating. The water supplied from the circulation pump 10 is subjected to RO treatment by the RO device 13, the concentrated water is discharged out of the system, and the permeated water is introduced into the pit 1d. The increase in the electric conductivity of the water in the pit 1d becomes slow due to the inflow of the permeated water, but the electric conductivity continues to increase and reaches the upper limit C2. Then, the forced replenishing water valve 22 is opened, and the replenishing water in the replenishing water tank 15 is supplied into the pit 1d via the pipes 19 and 20. [Selection] Figure 1

Description

  The present invention relates to a cooling tower system, and more particularly to a cooling tower system that recovers cooling tower blow water in an open circulation type cooling tower.

  In the cooling tower system, when high concentration operation is performed with less discharge (blow) of cooling water outside the system, dissolved salts are concentrated and the heat transfer surface is easily corroded. Scales as a sparingly soluble salt. If the scale adheres to the wall surface of the apparatus, a serious obstacle occurs in the operation of the boiler and heat exchanger, such as a decrease in thermal efficiency and blockage of piping. In recent years, for the purpose of saving water and saving energy, the movement of effectively using water as much as possible has become remarkable. However, in the case of further highly concentrated operation, there is a limit in suppressing the precipitation of scale.

  Therefore, the cooling tower blow water is passed through the MF membrane or UF membrane to remove turbidity in the blow water, and then RO membrane treatment is performed to remove ions, organic substances, etc., and return to the cooling tower (patent) Literatures 1-4).

JP 2002-18437 A JP 2003-1255 A Japanese Patent Laid-Open No. 2006-190224 JP, 2015-174030, A

  An object of this invention is to provide the cooling tower system which can reduce blow water and makeup water, and becomes easy to control.

The cooling tower system of the present invention includes a cooling tower to which a cooling water circulation line is connected, a measuring means for electric conductivity or specific resistance of the cooling water, and an electric conductivity measured by the measuring means is a predetermined upper limit value. if or when the specific resistance was increased to C ₂ is decreased to a predetermined lower limit value R _2, until the electrical conductivity or resistivity drops to a predetermined lower limit value C ₀ is increased to a predetermined upper limit value R ₀ A cooling tower system comprising makeup water supply means for supplying makeup water and recovery means for processing overflow water of the cooling tower and returning it to the cooling tower or circulation line, wherein the overflow water is used as the recovery means. A reverse osmosis membrane device for processing water pumped from the blow water basin, means for supplying the permeated water of the reverse osmosis membrane device to the cooling tower or circulation line, and electricity of the cooling water Conductivity or A specific resistance or the electrical conductivity or specific resistance and a control means for operating the recovery means in accordance with the water level of the blow water tank are provided.

In one aspect of the present invention, the control means increases the electrical conductivity of the cooling water to a predetermined intermediate value C ₁ (where C ₀ <C ₁ <C ₂ ) or the specific resistance has a predetermined intermediate value R. ₁ (provided that R ₂ <R ₁ <R ₀ ), the pump is started and the electrical conductivity decreases to the lower limit C ₀ or the specific resistance reaches the upper limit R ₀ . The pump is stopped when it rises to.

  In one aspect of the present invention, the water in the blow water tank is made turbid by the turbidity means and then supplied to the reverse osmosis membrane device.

  In the cooling tower system of this invention, the water recovery rate of a cooling tower can be made high by processing blow water and using it as cooling water.

  In the present invention, control is simplified by managing the blow water recovery means based on the electric conductivity or specific resistance of the cooling water or the electric conductivity or specific resistance and the water level of the blow water tank.

It is a flowchart which shows the cooling tower system which concerns on embodiment. It is a chart which shows the action | operation of the cooling tower system which concerns on embodiment.

  Hereinafter, embodiments will be described with reference to the drawings.

  As shown in FIG. 1, the cooling tower 1 of this cooling tower system is cooled in contact with the air introduced from the louver 1c while the cooling water sprinkled from the sprinkling pipe 1a flows down the filler layer 1b. The air that is stored in 1d (cooling tower lower water tank) and contains steam is configured to be exhausted into the atmosphere by a fan 1e. The cold water in the pit 1d of the cooling tower 1 is supplied to the heat exchanger 4 via the pump 2 and the pipe 3, and the return water from the heat exchanger 4 is returned to the water spray pipe 1a of the cooling tower 1 via the pipe 5. The

  The pit 1 d is provided with an overflow pipe 7. When the water level in the pit 1 d becomes higher than the inlet 7 a at the upper end of the overflow pipe 7, the cooling water in the pit 1 d passes through the overflow pipe 7 and the blow water tank 8. Flow into. The cooling tower 1 is provided with an electric conductivity meter 24 for measuring the electric conductivity of the cooling water in the pit 1d.

  The blow water tank 8 is provided with a water level sensor 9 and a circulation pump 10. Signals from the electrical conductivity meter 24 and the water level sensor 9 are input to the pump controller 10a, and the circulation pump 10 is controlled by signals from the pump controller 10a. Water supplied from the circulation pump 10 is supplied to the RO device 13 via the turbidifier 11 and the pipe 12. As the turbidizer 11, a filter, an MF membrane device, a UF membrane device, or the like can be used.

  The concentrated water of the RO device 13 is discharged out of the system, and the permeated water is supplied to the pit 1d through the pipe 14. Note that the downstream end of the pipe 14 may be connected to the pipe 3. In this embodiment, the equipment from the overflow pipe 7 and the blow water tank 8 to the pipe 14, the water level sensor 9, the electric conductivity meter 24, and the pump controller 10a constitute the recovery means.

  In order to store the makeup water supplied to the cooling tower 1, a makeup water tank 15 is installed, and a water level sensor 16 and a water pump 17 are installed in the makeup water tank 15. The end of the pipe 18 connected to the discharge port side of the water pump 17 is branched into pipes 19 and 20. One end of the pipe 19 is connected to the ball tap 21 of the pit 1d. The other end of the pipe 20 faces the pit 1d. A forced supply water valve 22 is provided in the pipe 20. The forced replenishment water valve 22 is controlled by a controller 23. The detection value of the electric conductivity meter 24 provided in the pit 1d is input to the controller 23.

  Next, the operation of this cooling tower system will be described with reference to FIGS.

If the operation of circulating and supplying cold water from the cooling tower 1 to the heat exchanger 4 is continued, the water level in the pit 1d gradually decreases as the cooling water evaporates and the electrical conductivity gradually increases as shown in FIG. . When the electrical conductivity is increased to a predetermined intermediate value C _1, the circulation pump 10 starts operation by a signal from the controller 10a. The water supplied from the circulation pump 10 passes through the turbidizer 11 and is then subjected to RO treatment by the RO device 13, the concentrated water is discharged out of the system, and the permeated water is introduced into the pit 1 d through the pipe 14.

The inflow of the permeate, increase in electric conductivity of the water in the pit 1d is slowed, but still continue the electrical conductivity increases further eventually reaches a predetermined upper limit value C _2. If it does so, the forced replenishment water valve 22 will be opened by the signal from the controller 23, and the replenishment water in the replenishment water tank 15 will be supplied in the pit 1d via the piping 19 and 20. FIG. (The pump 17 is configured to operate when the forced replenishment water valve 22 and the ball tap 21 are open.) As a result, the water level in the pit 1d gradually rises and the electrical conductivity gradually increases. To drop. When the electrical conductivity of the cooling water in the pit 1d is lowered to a predetermined lower limit value C _0, forcing makeup water valve 22 while being closed, the water pump 17 is stopped.

Electrical conductivity of the water in the pit 1d is forced makeup water valve 22 is opened until drops to the lower limit value C _0, makeup water is continuously supplied during this time pits 1d. Thereby, the electrical conductivity gradually decreases. As the makeup water is supplied, the water level in the pit 1d rises as described above, but the water level rise in the pit 1d stops at the overflow water level (the level of the inlet 7a). After the water level in the pit 1d reaches the overflow water level, the same amount of pit water (cooling water) as the amount of makeup water flowing in via the pipes 18 and 20 is overflowed until the forced makeup water valve 22 is closed. 7 flows into the blow water tank 8.

  With the inflow of overflow water, the water level in the blow water tank 8 rises. The rise in the water level in the blow water tank 8 continues until the forced refill water valve 22 is closed.

  As the forced replenishment water valve 22 is closed, the circulation pump 10 is stopped and the water supply to the RO device 13 in the blow water tank 8 is also stopped, so that the water level in the blow water tank 8 is kept constant thereafter. Kept. During this time, the electrical conductivity of the water in the pit 1d gradually increases, so that the above series of operations is repeated.

In FIG. 1, the electric conductivity meter 24 is installed, but a specific resistance meter is installed instead of the electric conductivity meter, and the specific resistance (or specific resistance and the water level of the blow tank) is measured by the specific resistance meter. Control may be performed based on this. In this case, if over the course of operation of the cooling tower resistivity of the water in the pit 1d is reduced to a predetermined intermediate value R _1, the circulation pump 10 starts operation by a signal from the controller 10a, RO 13 Permeated water is introduced into the pit 1d.

The inflow of the permeate, increase in electric conductivity of the water in the pit 1d is slowed, but the specific resistance is further continued to decrease and eventually reach a predetermined lower limit value R _2. If it does so, the forced replenishment water valve 22 will be opened by the signal from the controller 23, and the replenishment water in the replenishment water tank 15 will be supplied in the pit 1d via the piping 19 and 20. FIG. Thereby, the water level in the pit 1d gradually rises and the specific resistance gradually rises. When the specific resistance of the cooling water in the pit 1d rises to a predetermined upper limit value _R0 , the forced refill water valve 22 is closed and the water pump 17 is stopped.

As the specific resistance increases to the upper limit value R ₀ , the circulation pump 10 is stopped and the water supply to the RO device 13 in the blow water tank 8 is stopped as the forced replenishment water valve 22 is closed. To do. Thereafter, the specific resistance of water in the pit 1d gradually decreases, so that the above series of operations is repeated.

  The blow water discharged outside the system during operation of the cooling tower system is only the concentrated water of the RO device 13, and the recovery rate of makeup water is high. Further, since the circulation pump 10 is ON / OFF controlled according to the electric conductivity or specific resistance of the cooling water, the control is simple. The circulating pump 10 may be operated when the detected water level of the water level sensor 9 in the blow water tank 8 is equal to or higher than a predetermined upper limit value, and the circulating pump 10 may be stopped when the detected water level is lower than a predetermined lower limit value. The upper limit is preferably about 60 to 80% of the full water level of the blow water tank 8, and the lower limit is preferably about 5 to 40% of the full water level.

  As described above, when the water level in the pit 1d falls below a predetermined control value (the opening level of the ball tap 21) during the operation of the cooling tower system, the ball tap 21 is opened and the replenishment in the replenishing water tank 15 is performed. Water is supplied to the pit 1d through the ball tap 21. Although illustration is omitted, when the water level in the replenishing water tank 15 detected by the water level sensor 16 falls below a specified value, a water injection mechanism for injecting water such as industrial water, ground water or tap water into the replenishing water tank 15 is provided. Is provided.

  In this embodiment, the slime or the scale inhibitor injected into the pit 1d is supplied to the RO device 13 through the turbidizer 11, so that the slime in the RO device 13 Scale prevention effect is also obtained.

  The above embodiment is an example of the present invention, and the present invention may have a configuration other than the above. For example, in the above embodiment, when the water level in the pit 1 d becomes higher than the inlet 7 a at the upper end of the overflow pipe 7, the cooling water higher than the inlet 7 a in the pit 1 d is blown through the overflow pipe 7. 8 is provided with a pipe line connecting the pipe 3 (especially the discharge side of the pump 2) and the blow water tank 8 and a valve installed in the pipe line to provide cooling water in the pit 1d. When the water level becomes higher than the specified water level (the water level at the inlet 7a), the valve opens, and cooling water higher than the specified water level in the pit 1d flows into the blow water tank 8 through the pipe line. Good.

DESCRIPTION OF SYMBOLS 1 Cooling tower 4 Heat exchanger 8 Blow water tank 13 RO apparatus 15 Replenishment water tank 24 Electric conductivity meter

Claims (3)

A cooling tower connected to a cooling water circulation line;
Means for measuring the electrical conductivity or resistivity of the cooling water;
When the electrical conductivity measured by the measuring means increases to a predetermined upper limit value C ₂ or when the specific resistance decreases to a predetermined lower limit value R ₂ , the electrical conductivity decreases to a predetermined lower limit value C ₀ . Or makeup water supply means for supplying makeup water until the specific resistance rises to a predetermined upper limit value _R0 ,
A cooling tower system having recovery means for treating overflow water of the cooling tower and returning it to the cooling tower or the circulation line,
As the recovery means,
A blow tank for receiving the overflow water;
A reverse osmosis membrane device for treating water pumped from the blow water tank;
Means for supplying permeated water of the reverse osmosis membrane device to the cooling tower or circulation line;
A cooling tower system comprising: electric conductivity or specific resistance of cooling water, or control means for operating the recovery means in accordance with the electric conductivity or specific resistance and the water level of the blow water tank. In Claim 1, the control means increases the electrical conductivity of the cooling water to a predetermined intermediate value C ₁ (where C ₀ <C ₁ <C ₂ ) or the specific resistance is a predetermined intermediate value R ₁ ( However, when it falls to R ₂ <R ₁ <R ₀ ), the pump is started, and the electrical conductivity falls to the lower limit value C ₀ or the specific resistance rises to the upper limit value R _0. Then, the cooling tower system characterized by stopping the pump.   3. The cooling tower system according to claim 1, wherein the water in the blow water tank is turbidized by a turbidity means and then supplied to the reverse osmosis membrane device.

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