JP3985499B2 - Scale prevention device and scale prevention method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a scale prevention device that prevents adhesion of scale by applying a voltage between at least one pair of electrodes to elute metal ions, and a scale prevention method using the scale prevention device.
[0002]
[Prior art]
In an open circulating cooling water system, the concentration of salts in the makeup water increases as water is circulated and reused, and scale components such as calcium carbonate and silica adhere to heat exchanger tubes and heat transfer. Causes inhibition.
[0003]
Conventionally, scale prevention measures may be taken by adding a scale inhibitor, but as a scale prevention technique that does not use chemicals, metal ions that have a scale prevention effect are eluted into the aqueous system by applying a voltage between the electrodes. There is a way. For example, since aluminum ions suppress the precipitation of calcium carbonate, stainless steel and aluminum, or carbon and aluminum are used in combination with the cathode and anode, and the aluminum ions are eluted from the aluminum electrode in the circulating water to heat the calcium carbonate in the heat exchanger. Methods for reducing scale adhesion are known. Japanese Patent Application Laid-Open No. 6-296970 describes a method for preventing slime and scale by using an external electrode and applying a DC voltage to a pair of copper electrodes to elute copper ions.
[0004]
The scale preventing device for preventing scale by the metal ions eluted by electrolysis as described above generally includes a casing through which water to be treated is passed, and at least one pair of electrodes arranged in the casing. .
[0005]
When such a scale prevention device is incorporated in a circulating cooling water system or the like, the scale prevention device is always in a state where water supply pressure is applied, so the casing through which the water to be treated must flow must have a pressure-resistant structure. Therefore, in the conventional scale prevention device, the casing is made of metal such as stainless steel.
[0006]
[Problems to be solved by the invention]
However, in a scale prevention device for a metal casing, if there is a poor insulation, the electrodes may be short-circuited through the casing, causing a failure of the device. Further, the metal casing is heavy and easily corrodes.
[0007]
SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned conventional problems, and to provide a scale prevention device that is excellent in insulation, can be prevented from corrosion and can be reduced in weight, and a scale prevention method using the scale prevention device.
[0008]
[Means for Solving the Problems]
The scale prevention device of the present invention is a scale prevention device that treats the water extracted from the circulating cooling water system and returns it to the circulating cooling water system, and a casing through which the water to be treated extracted from the circulating cooling water system is passed, An anti-scale device that elutes metal ions having an anti-scale effect from the electrodes by applying a voltage between the electrodes, and the casing includes : It is composed of a synthetic resin of any one of vinyl chloride resin, acrylic resin, and polytetrafluoroethylene .
[0009]
Casing of the scale prevention device of the present invention, since the synthetic resin, superior insulating properties, the Ke pacing is of high corrosion resistance, it is also possible to reduce the weight of the device.
[0010]
The scale prevention method of the present invention is to prevent the scale from adhering by passing water to be treated through such a scale prevention apparatus of the present invention, and can perform a stable scale prevention treatment over a long period of time.
[0011]
In addition, the scale prevention apparatus of this invention is suitable for being used for the location where a water flow pressure is low. For example, the scale prevention device of the present invention is suitable for treating water to be treated which has been passed through a filtration device and whose water supply pressure has decreased.
[0012]
Scale prevention equipment of the present invention, rather than passed through the high water pressure circulating water, passed through the low water of water supply pressure and withdrawing from the cooling tower pits. In this case Te smell, it is preferable that the pressure is passed through the Filtration device is passed through the water was reduced to the scale prevention device.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0014]
FIG. 1A is a schematic sectional view showing an embodiment of a scale prevention device, and FIG. 1B is a system diagram of an open circulation cooling water system showing an embodiment of the scale prevention method of the present invention.
[0015]
The scale prevention device of FIG. 1A includes a casing 2 provided with an inlet 2A for treated water and an outlet 2B for treated water, and electrodes 3A and 3B provided in the casing 2. A direct current voltage is applied between the electrodes 3A and 3B by the power supply device 4, and metal ions are eluted from the electrodes 3A or 3B, whereby the scale treatment of the water to be treated is performed.
[0016]
In the present invention, the casing 2 is made of synthetic resin. Synthetic resins constituting the casing 2, the strength, the surface in vinyl chloride resins such as durability, acrylic resin, Ru Ah with polytetrafluoroethylene down. Na us, the synthetic resin may contain a non-conductive fibers such as glass fiber.
[0017]
The pressure resistance strength of the synthetic resin casing 2 is appropriately determined depending on the capacity of the casing 2, the pressure resistance depending on the use of the scale prevention device 1, and the like. It is preferable that the water pressure is sufficiently tolerable. In general, in order to increase the pressure resistance of the casing 2, a rib may be provided on the casing 2 or a reinforcing band may be wound.
[0018]
The shape of the casing 2 is preferably a cylindrical shape, but may be other shapes.
[0019]
The metal ions eluted by the scale prevention apparatus 1 are particularly preferably aluminum ions, iron ions, and zinc ions. These may be used alone or in combination of two or more. Therefore, it is preferable that at least one of the electrodes 3A and 3B is made of aluminum, iron, or zinc. The other of the electrodes 3A and 3B may be a highly corrosion-resistant conductive material such as carbon, titanium, and stainless steel.
[0020]
Note that the polarities of the electrodes 3A and 3B may be alternately reversed, thereby preventing the elution inhibition of metal ions due to the adhesion of scale to the surfaces of the electrodes 3A and 3B. In this case, the polarity inversion of the electrodes 3A and 3B may be periodically performed, for example, every 1 hour to 1 day, or may be performed when the electrolysis voltage becomes a predetermined value or more due to the adhesion of the scale.
[0021]
FIG.1 (b) has shown the method of preventing the scale of an open circulation cooling water system using the scale prevention apparatus 1 of this invention. In this circulating cooling water system, the circulating cooling water is supplied from the cooling tower 10 to the heat exchanger 12 through the circulation pipe 11 having the pump P ₁ , and the return water is returned to the cooling tower 10 through the pipe 13. 14 is a supply water introduction pipe, and 15 is a blow pipe.
[0022]
In this embodiment, extracted from the pipe 16 to the water in the pit comprises a pump P ₂ of the cooling tower 10, after filtration through a filter 20, a metal underwater to deliver the scale preventing apparatus 1 from the pipe 17 ions Then, the water from which the metal ions are eluted in the pipe 18 is returned to the pit of the cooling tower 10.
[0023]
As described above, when the scale prevention device 1 is not directly incorporated in the circulating cooling water system but is incorporated in another system from which the water of the circulating cooling water system has been extracted, a large water supply pressure is not applied to the scale prevention device 1. In particular, since the water supply pressure is low on the downstream side of the filter 20, even a synthetic resin casing with low pressure resistance can be applied sufficiently.
[0024]
In such circulating cooling water scale prevention treatment, it is preferable to elute metal ions so that the aqueous metal ion concentration is 0.01 ppb to 1 ppm, particularly 0.1 to 10 ppb. If the aqueous metal ion concentration is less than 0.01 ppb, a sufficient scale adhesion preventing effect cannot be obtained, and if it exceeds 1 ppm, metal salts may adhere. The elution amount of the metal ions can be calculated from the current value according to Faraday's law. Therefore, the elution amount of the metal ions can be controlled by controlling the value of the electrolysis current flowing between the electrodes.
[0025]
In order to prevent the scale from adhering to the electrode of the scale prevention device, it is desirable that the flow rate of water on the electrode surface is high. That is, the slower the flow rate, the easier the scale adheres to the electrode surface. Therefore, the flow rate of the water to be treated on the electrode surface is preferably 0.1 m / sec or more, particularly 0.1 to 100 m / sec.
[0026]
In the present invention, a slime prevention device that generates residual chlorine by electrolysis may be provided after the scale prevention device 1 to prevent slime together with the scale.
[0027]
Scale prevention device of the present invention, transmission as described above for the water pressure, so that less 0.1 to 1.0 MPa, it is preferable that passed through the scale prevention device after step down as needed.
[0028]
【The invention's effect】
As described in detail above, the scale prevention device of the present invention is excellent in electrical insulation because the casing is made of synthetic resin . In addition , the weight of the apparatus can be reduced, the handleability is improved, and the corrosion resistance of the casing is improved. In addition, the cost of the casing can be reduced.
[0029]
According to the scale preventing method of the present invention, by using such a scale prevention device, processes the water circulation cooling water system, it is possible to prevent scale for a long period stably and reliably in the system.
[Brief description of the drawings]
FIG. 1 (a) is a schematic cross-sectional view showing an embodiment of a scale prevention device, and FIG. 1 (b) is a system diagram of an open circulating cooling water system showing an embodiment of the scale prevention method of the present invention. It is.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Scale prevention apparatus 2 Casings 3A, 3B Electrode 4 Power supply apparatus 10 Cooling tower 12 Heat exchanger 20 Filter

Claims (3)

A scale prevention device for treating water drawn from the circulating cooling water system and returning it to the circulating cooling water system, wherein the treated water drawn from the circulating cooling water system is passed through, and at least the casing disposed in the casing A pair of electrodes;
In a scale prevention apparatus for eluting metal ions having a scale prevention effect from the electrodes by applying a voltage between the electrodes,
The scale prevention device , wherein the casing is made of a synthetic resin of any of vinyl chloride resin, acrylic resin, and polytetrafluoroethylene . 2. The scale prevention device according to claim 1, wherein water to be treated which has been pulled out of the circulating cooling water system and passed through the filtration device and has a reduced water supply pressure is passed through the casing.   A scale prevention method characterized by passing water to be treated through the scale prevention apparatus according to claim 1 or 2 and applying a voltage to the electrode.

Images