JP2018146225A - Cooling tower system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cooling tower system capable of reducing blow water and make-up water, and simplifying control.SOLUTION: When an operation for circulating and supplying cold water from a cooling tower 1 to a heat exchanger 4 is continued, a water level in a pit 1d is gradually lowered, and electric conductivity is gradually increased. When the electric conductivity is increased to an intermediate value C, an operation of a submerged pump 8 is started. Feed water from the submerged pump 8 is RO-processed by an RO device 13 to discharge concentrated water to the outside of a system and to introduce permeable water to the pit 1d. When the water level is lowered to a lower limit value H, a ball tap 21 is opened and make-up water is supplied until the water level is increased to an upper limit value H. When the electric conductivity is lowered to a prescribed value Cin accompany with the supply of make-up water, the submerged pump 8 is stopped.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a cooling tower system, and more particularly to a cooling tower system provided with a mechanism for supplying cooling water in a cooling tower to a reverse osmosis membrane device (RO device) 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 circulation line of cooling water is connected, water in the cooling tower is pumped to a reverse osmosis membrane device, and the permeated water of the reverse osmosis membrane device is sent to the cooling tower. Alternatively, the recovery means supplied to the circulation line, the measurement means for the electric conductivity or specific resistance of the cooling water, and the electric conductivity or specific resistance measured by the measurement means rises to a predetermined intermediate value C ₂ or the ratio When the resistance decreases to a predetermined intermediate value R ₂ , the electrical conductivity decreases to a predetermined intermediate value C ₁ (C ₁ <C ₂ ) or the specific resistance reaches a predetermined intermediate value R ₁ (R ₁ > R). _{And 2} ) a control means for operating the recovery means until it rises.

In one aspect of the present invention, a ball tap that opens when the water level in the cooling tower reaches a predetermined lower limit value H ₀ and supplies makeup water to the cooling tower and closes when the water level rises to the predetermined upper limit value H ₁ is provided. I have.

  In one aspect of the present invention, a forced replenishing water valve is provided that opens the recirculation line when cooling water is flowing and supplies replenishing water to the cooling tower.

  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 the present invention, when the electrical conductivity of the cooling water is high or the specific resistance is low, the cooling water is treated with the RO device and used as the cooling water, so that the water recovery rate of the cooling tower is obtained. Can be high. In the present invention, since the recovery means is controlled according to the electric conductivity or specific resistance of the cooling water, the control is easy.

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 flows out through the overflow pipe 7. 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. In addition, a sensor 26 that detects water flowing down the filler layer 1b is provided.

  The pit 1d is provided with a submersible pump 8 for feeding water in the pit 1d. A signal from the electric conductivity meter 24 is input to the pump controller 10, and the submersible pump 8 is controlled by a signal from the pump controller 10. Water supplied from the submersible pump 8 is supplied to the RO device (reverse osmosis membrane device) 13 via the pipe 9, the turbidizer 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 pipe 14 may be connected to the pipe 3.

In order to supply makeup water to the cooling tower 1, a makeup water pipe 18 is installed. Industrial water, tap water, groundwater, etc. are used as makeup water. The end of the pipe 18 is branched into pipes 19 and 20. One end of the pipe 19 is connected to a ball tap (or a float valve device) 21 of the pit 1d. The ball tap (or float valve device) has an operating characteristic that the water level in the pit 1d is opened drops to a predetermined lower limit value H _0, and closes when raised to a predetermined upper limit value H ₁ .

  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.

When the operation of circulating and supplying cold water from the cooling tower 1 to the heat exchanger 4 is continued in a state where the water level in the pit 1d is higher than the lower limit H ₀ , the pit 1d is accompanied by the evaporation of the cooling water as shown in FIG. The water level in the inside gradually decreases, and the electrical conductivity gradually increases. The electrical conductivity to reach a predetermined intermediate value C ₂ water pump 8 is stopped. When the electrical conductivity reaches the intermediate value C ₂ (time t ₁ ), the submersible pump 8 starts to operate according to a signal from the controller 10. The water supplied from the submersible pump 8 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.

By part of the cooling water is returned is RO process, increase of the electrical conductivity of the cooling water in the pit 1d is slowed, because the makeup water is not supplied from the supply water pipe 18, even after the time t ₁ The electrical conductivity gradually increases and the water level in the pit 1d also gradually decreases. The submersible pump 8 continues to operate.

It becomes a time t _2, the so water level in the pit 1d reaches the lower limit value H _0, ball tap 21 is opened, replenishing water is supplied to the pit 1d. Thereby, the electrical conductivity of the cooling water in the pit 1d starts to decrease. Ball tap 21 is opened until the time t ₄ when the water level reaches the upper limit value H _1. During this _t 2 ~t _4, electric conductivity gradually decreases.

At time _{t 3} between t ₂ ~t _4, the electrical conductivity is reduced to a predetermined intermediate value _{C 1.} Then, the submersible pump 8 is stopped by a signal from the controller 10. Since the ball tap 21 after the time t ₃ in the open, makeup water is supplied into the pit 1d, the water level rises further, the electrical conductivity is further reduced. Since the water level at time t ₄ reaches the upper limit value H _1, ball tap 21 is closed. Thus, the time t ₄ later, the water level in the pit 1d is gradually lowered, the electrical conductivity gradually increases, a state at time t _1. Thereafter, the above series of operations is repeated.

Thus, the water level in the pit 1d is actuated balltap 21 so as to be between the lower limit value H ₀ and the upper limit value H _1, during which the cooling water and electrical conductivity of the cooling water exceeds the intermediate value C ₂ RO processing starts, and when it falls below the intermediate value C ₁ (C ₁ <C ₂ ), the RO processing stops. Therefore, the electrical conductivity of the cooling water does not increase excessively, and the cooling water is prevented from being excessively RO processed.

In FIG. 1, the electrical conductivity meter 24 is installed, but a specific resistance meter may be installed instead of the electrical conductivity meter, and control may be performed based on the specific resistance measured by the specific resistance meter. In this case, when the specific resistance of the water in the pit 1d with the passage of operation of the cooling tower is reduced to a predetermined intermediate value R ₂ (time t _1), water pump 8 is started actuated by a signal from the controller 10 To do. The water supplied from the submersible pump 8 passes through the turbidizer 11 and is then subjected to RO treatment by the RO device 13, and the permeate is returned to the pit 1d, so that the specific resistance of the cooling water in the pit 1d is slowly lowered. becomes, even after the time t ₁ the resistivity gradually decreases, the water level in the pit 1d gradually decreases. The submersible pump 8 continues to operate.

It becomes a time t _2, the so water level in the pit 1d reaches the lower limit value H _0, ball tap 21 is opened, replenishing water is supplied to the pit 1d. Thereby, the specific resistance of the cooling water in the pit 1d starts to increase. Ball tap 21 is opened until the time t ₄ when the water level reaches the upper limit value H _1. During this _t 2 ~t _4, the resistivity gradually increases.

At time _{t 3} between t ₂ ~t _4, the resistivity rises to a predetermined intermediate value _{R 1.} Then, the submersible pump 8 is stopped by a signal from the controller 10. Since the ball tap 21 after the time t ₃ in the open, makeup water is supplied into the pit 1d, the water level rises further, the resistivity is further increased. Since the water level at time t ₄ reaches the upper limit value H _1, ball tap 21 is closed. Thus, the time t ₄ later, the water level in the pit 1d is gradually lowered, the resistivity gradually decreases, a state at time t _1. Thereafter, the above series of operations is repeated.

The electric conductivity of the cooling water has the lowest minimum value C ₀ at time t ₄ when the ball tap is opened → closed, and becomes the maximum value C ₂ at time t ₂ when the ball tap is closed → open. When the electrical conductivity exceeds a predetermined upper limit C ₃ (C ₃ > C ₂ ) for some reason, the forced replenishing water valve 22 is opened (or the opening degree is large), and the replenishing water is automatically poured into the pit 1d. Blowing is preferred. (Note that the specific resistance has the highest maximum value R ₀ at time t ₄ when the ball tap is opened → closed, and becomes the minimum value R ₂ at time t ₂ when the ball tap is closed → opened. Is less than or equal to a predetermined lower limit value R ₃ (R ₃ > R ₂ ), it is preferable to open the forced replenishment water valve 22 (or open large) and perform an automatic blow to inject replenishment water into the pit 1d. .)

  In this embodiment, the ball tap operation and the submersible pump operation shown in FIG. 2 are performed, so that the number of automatic blows is reduced or the automatic blow is hardly performed.

  In this embodiment, the makeup water is supplied mainly by the ball tap 21.

  The operation of the cooling tower 1 is detected based on the operation signal of the pump 2 for circulating the cooling water or the flowing water detection signal of the sensor 26. While the cooling tower 1 is operating, the forced replenishment water valve 22 is opened to make a small amount. You may make it supply the makeup water (for example, about 1 to 20% of the evaporation / scattering loss amount per unit time from the cooling tower 1) continuously to the pit 1d.

  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 submersible pump 8 is ON / OFF controlled according to the electric conductivity or specific resistance of the cooling water, the control is simple.

  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, water may be supplied to the RO device 13 using a pump other than the submersible pump. 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. The drainage pipe is connected to the pipe 3 (particularly the discharge side of the pump 2), and a valve is provided in the pipe. The cooling water level in the pit 1d is set to the specified level ( The valve may be opened when the water level becomes higher than the water level of the inlet 7a, and cooling water higher than the specified water level in the pit 1d may be discharged through the pipe line.

DESCRIPTION OF SYMBOLS 1 Cooling tower 4 Heat exchanger 8 Submersible pump 11 Turbid remover 13 RO apparatus 15 Supply water tank 24 Electric conductivity meter

Claims (4)

A cooling tower connected to a cooling water circulation line;
Recovery means for pumping water in the cooling tower to a reverse osmosis membrane device by a pump and supplying permeated water of the reverse osmosis membrane device to the cooling tower or a circulation line;
Means for measuring the electrical conductivity or resistivity of the cooling water;
When the electrical conductivity or specific resistance measured by the measuring means increases to a predetermined intermediate value C ₂ or when the specific resistance decreases to a predetermined intermediate value R ₂ , the electric conductivity becomes a predetermined intermediate value C _1. And a control means for operating the recovery means until the resistance drops to (C ₁ <C ₂ ) or the specific resistance rises to a predetermined intermediate value R ₁ (R ₁ > R ₂ ). Tower system. According to claim 1, comprising a ball tap the water level in the cooling tower becomes a predetermined lower limit value H ₀ and by opening up water supplied to the cooling tower, and closes when raised to a predetermined upper limit value H ₁ A cooling tower system characterized by that.   3. The cooling tower system according to claim 1, further comprising a forced supply water valve that opens when the cooling water is flowing through the circulation line and supplies makeup water to the cooling tower.   The cooling tower system according to any one of claims 1 to 3, wherein water from the pump is turbidized by a turbidity means and then supplied to the reverse osmosis membrane device.

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