JP2002361286A - Scale adhesion prevention method and prevention device - Google Patents

Abstract

(57) [Problem] To provide a scale adhesion preventing method and an apparatus which can simultaneously prevent adhesion of a calcium carbonate scale and a silica scale in a circulating cooling water system without using a chemical. In a circulating cooling water system, there is provided a method for preventing scale adhesion, wherein circulating water is treated by a calcium carbonate modifying means and a silica removing device, and a calcium carbonate modifying means and a silica removing device. Scale adhesion prevention device in circulating cooling water system.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method and an apparatus for preventing scale adhesion. More specifically, the present invention, in a circulating cooling water system, without the use of drugs,
The present invention relates to a scale adhesion prevention method and a scale prevention device capable of simultaneously preventing adhesion of a calcium carbonate scale and a silica scale.

[0002]

2. Description of the Related Art In a circulating cooling water system, the salt concentration in the circulating cooling water increases with the circulating use of water, and calcium carbonate scales and silica scales are generated. Causes obstacles such as deposition. When high concentration operation is performed for effective use of water, scale is particularly likely to occur. In order to prevent scale adhesion, scale inhibitors such as chelating agents, anionic polymers, phosphonic acids, and polyphosphoric acids are used.Manage the cost of the scale inhibitors, control the scale inhibitors, and add a predetermined amount to the cooling water system It is unavoidable that it takes time and effort. For this reason, a method of preventing scale adhesion by physical means without using a drug has been attempted. For example,
Japanese Patent Application Laid-Open No. Hei 4-18982 discloses a three-dimensional electrode type electrolytic cell in which cooling water is polarized by applying a voltage as a method for electrochemically removing ions such as calcium, magnesium and silicon dissolved in the cooling water. To convert the metal ions into hydroxides or oxides and deposit them on electrodes. However, when an electrolytic cell is used, a leakage current is generated, and metal members such as pipes and heat exchangers may be corroded, and there is no danger of explosion due to generation of hydrogen gas and oxygen gas. As a physical means without using electrolysis, US Pat. No. 5,074,998 discloses a fluctuating magnetic field in which a solenoid coil is wound around the outer periphery of a cooling water system pipe and a frequency-modulated power is supplied to the coil. An apparatus has been proposed in which the surface charge of all the fine particles in water is increased by forming, and scaling is prevented by repulsion of the fine particles. Prevention of scale by a magnetic field is also performed on permanent magnets.For example, when a magnetic processing unit equipped with permanent magnets is installed in the middle of cooling water piping, water is flowed at a certain flow rate or more, and when it crosses the magnetic field at right angles A method has been proposed in which clusters of water are made finer by the generated ionic current and aggregation of scale components is suppressed. JP-A-63-39690 discloses a method of preventing scale by applying electric energy to a liquid to ionize the liquid, by bringing two members having different electrochemical potentials into contact with the liquid, and applying a potential difference between the two members. And ionizing the liquid to prevent crystallization and precipitation of salts such as calcium, magnesium and silica. As an example, a permanent battery composed of an aluminum electrode and a carbon electrode is used, water is ion-activated by an electromotive force generated between different types of electrodes, and scales of calcium, magnesium, etc. are generated by the hydration energy of polarized water molecules. There are techniques for ion sequestering components. Japanese Patent Laid-Open No. 5-
Japanese Patent No. 57286 discloses an electric field in which a pair of electrodes made of a permanent magnet and a dissimilar metal are provided facing a water passage as an apparatus for selecting an induced current to an optimum value without using an external power supply and removing scale in water. An apparatus using both a magnetic field and a magnetic field has been proposed. Japanese Patent Application Laid-Open No. 7-82000 discloses a composite porous ceramic ball obtained by sintering a ceramic containing a diamagnetic compound and magnetizing the same. A method of dispersing the + metal ion has also been proposed.
Furthermore, a method has been proposed in which a ceramic ball baked by mixing tourmaline with a ceramic raw material is immersed in water, and hydroxyl ions are generated by electrolysis of weak water by an electric current emitted therefrom, thereby preventing scale adhesion. ing. However, although these scale adhesion preventing means exhibit a certain effect in preventing calcium carbonate scale adhesion, in a cooling water system in which a large amount of silica is present in makeup water, it is possible to prevent silica scale adhesion. It is difficult, and to prevent silica-based scale adhesion,
It was necessary to separately add a drug such as a polymer. For this reason, there has been a demand for a scale adhesion preventing method and an apparatus which can simultaneously prevent the adhesion of calcium carbonate scale and silica scale without using a chemical.

[0003]

SUMMARY OF THE INVENTION The present invention provides a method and an apparatus for preventing the adhesion of calcium carbonate scale and silica scale simultaneously in a circulating cooling water system without using a chemical. It was made for the purpose of providing.

[0004]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems, and as a result, in the circulating cooling water system, the use of a calcium carbonate modifying means and a silica removing device in combination has enabled the use of a drug. It has been found that the use of calcium carbonate-based scale and silica-based scale can be simultaneously and effectively prevented without using the same, and the present invention has been completed based on this finding. That is, the present invention
(1) In a circulating cooling water system, a method of preventing scale adhesion, wherein circulating water is treated by a calcium carbonate modifying means and a silica removing device, and (2) the calcium carbonate modifying means is circulated by a permanent magnet or a solenoid coil type magnet. One or more combinations selected from the group consisting of magnetic treatment of water, means for eluting metal ions into circulating water, means for placing ceramic balls in circulating water, and means for adding a seed crystal of calcium carbonate to circulating water. 2. The method for preventing scale adhesion according to item 1, wherein the silica removing device is a column having an inlet and an outlet for water to be treated and packed with silica gel particles. Method, (4) Prevention of scale adhesion in circulating cooling water system characterized by having calcium carbonate modifying means and silica removing device The apparatus, (5) the calcium carbonate modifying means is a magnetic treatment means for circulating water with a permanent magnet or a solenoid coil type magnet, a means for eluting metal ions into circulating water, a means for placing ceramic balls in circulating water, and a kind of calcium carbonate. 5. The scale adhesion preventing device according to claim 4, which is one or a combination of two or more selected from the group consisting of means for adding crystals to circulating water, and (6) the silica removing device comprises: 5. A scale adhesion preventing device according to claim 4, which has an outlet and is a column filled with silica gel particles.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the method for preventing scale adhesion of the present invention, circulating water is treated in a circulating cooling water system by a calcium carbonate modifying means and a silica removing device. The scale adhesion preventing device of the present invention has a calcium carbonate modifying means and a silica removing device. INDUSTRIAL APPLICABILITY The method and apparatus of the present invention can be particularly suitably applied to a circulating cooling water system in which high calcium concentration and high silica concentration and high concentration operation are performed. The means for modifying calcium carbonate used in the present invention is not particularly limited. For example, means for magnetically treating circulating water with a permanent magnet or a solenoid coil type magnet, means for eluting metal ions into circulating water, means for placing ceramic balls in circulating water And a means for adding a seed crystal of calcium carbonate to circulating water, a means of combining different kinds of electrodes and installing the same inside or outside the circulating water pipe. One of these calcium carbonate modifying means can be used alone, or two or more can be used in combination.

There is no particular limitation on the permanent magnet used in the present invention, and examples thereof include permanent magnets such as alnico, barium-ferrite, iron-neodymium-boron, and samarium-cobalt. The permanent magnet is installed in the pipe so that the water containing the scale component flows across the magnetic field at right angles. The flow rate of water should be more than 1.5m / sec.
It is preferable to appropriately select the piping diameter of the permanent magnet installation portion. When a magnetic field is formed in water by a permanent magnet and the magnetic flux is cut off by the flow of water, an ionic current of about several mA is generated, the water clusters become finer, and the scale components in the water are dispersed to prevent adhesion only. In addition, the scale which has already adhered can be softened and peeled off. The solenoid coil type magnet used in the method of the present invention is used by winding a coil around the outside of the cooling water system pipe, so that it can be installed in the existing cooling water system without any modification work. There is no particular limitation on the material of the pipe, for example, copper, stainless steel,
Examples include bronze and plastic piping.
It is preferable that alternating current is applied to the solenoid coil, and the frequency is modulated in the range of 2,000 to 7,000 Hz and the amplitude is also modulated by computer control. When a magnetic field is formed in water by the solenoid coil type magnet, the charge on the surface of the fine particles of the scale component present in the water is increased and repel each other. It does not adhere to walls. The condition of the magnetic field that charges the fine particles is
Although it depends on the size of the particles, the surface charge of all the particles can be increased by modulating the frequency and amplitude of the current applied to the solenoid coil.

The means for eluting metal ions used in the present invention into circulating water is not particularly limited. For example, a method for eluting metal ions by electrolyzing a metal electrode of aluminum, iron, zinc or the like in circulating water with an external power supply. Alternatively, a method of disposing a carbon electrode at a counter electrode of a metal electrode and short-circuiting them via a variable resistor to elute metal ions can be used. The ceramic ball used in the present invention is not particularly limited, and examples thereof include a ceramic ball containing a diamagnetic compound and a ceramic ball containing tourmaline. The installation position of the ceramic ball is not particularly limited, and for example, can be immersed in a pit of a cooling tower. A ceramic ball containing a diamagnetic compound is prepared by kneading a diamagnetic compound such as silver iodide, aluminum chloride, or boron oxide, a ceramic material, and a binder, calcining, sintering, and then magnetizing to obtain a composite porous material. Quality ceramic balls. Since the ceramic ball containing the diamagnetic compound has an electromagnetic wave function, it generates oxygen ions and negative metal ions, finely clusters water,
It can prevent scaling of positive metal ions of scale components such as magnesium, and can soften and peel off scales that have already adhered. A ceramic ball containing tourmaline can be obtained by pulverizing tourmaline crystals such as magnesite tourmaline or iron tourmaline, mixing with a ceramic material, and forming a spherical shape. By immersing the ceramic ball containing tourmaline in water, the current released from the ceramic ball causes weak electrolysis of water, and the resulting hydroxyl ions give the water a mild surface activity, exfoliate the scale, Remove.

[0008] The seed crystal of calcium carbonate used in the present invention is not particularly limited, and for example, any of calcite, aragonite and vaterite can be used. The average particle size of the seed crystal is not particularly limited, but is preferably from 0.01 to 100 μm, and more preferably from 0.1 to 10 μm. If the average particle size of the seed crystal is less than 0.01 μm, the scale component adheres to the surface and the crystallized particles are also small, which may make it difficult to settle and separate as sludge. If the average particle size of the seed crystal exceeds 100 μm, the effective surface area for the crystallization due to the attachment of the scale component will be smaller than the added amount, and the required added amount of the seed crystal may be increased. The concentration of the seed crystal is not particularly limited, but the concentration of the seed crystal in the circulating cooling water is 0.1 to 100 mg.
/ L, more preferably 1 to 10 mg / L. 0.1mg concentration of seed crystal in circulating cooling water
If the ratio is less than / L, precipitation of scale components on the surface of the seed crystal becomes insufficient, and scale may adhere to the wall surface of the cooling water system. Seed concentration in circulating cooling water is 100mg
/ L or less provides a sufficient scale prevention effect.
It is not necessary to add more than 00 mg / L of seed crystals. In the present invention, the place where the seed crystal is added is not particularly limited, but by adding the seed crystal to the pit of the cooling tower, the seed crystal can be easily added without requiring a special device. The seed crystal can be added as solid fine particles, but is preferably added as an aqueous dispersion from the viewpoint of workability. In order to stabilize the aqueous dispersion of the seed crystal, a thickener can be added to the aqueous dispersion.

The combination of the different types of electrodes used in the present invention is not particularly limited, and examples thereof include a combination of an aluminum electrode and a carbon electrode, and a combination of a silver electrode and a copper electrode. There is no particular limitation on the method of installing the different types of electrodes,
For example, a part of the circulating water pipe can be provided with an aluminum cylinder and a carbon rod in the direction of the central axis to allow the different electrode to contact the circulating water, or a part of the circulating water pipe is made of a plastic pipe and A ring-shaped aluminum electrode and a carbon electrode can also be provided. When the dissimilar electrode and the circulating water come into contact with each other, it is preferable that there be no air bubbles and no air pool in the water. Therefore, it is preferable that the cooling water system pipe is vertical and installed at a position where water flows upward from below. When water is flowed between the combined different electrodes, a minute voltage of 1 V or less is generated, and a very small current of 1 μA or less flows, whereby water molecules are ion-activated and polarized. Scale components such as calcium and magnesium are sequestered by the hydration energy of the polarized water molecules. As a result, the crystallization of the scale is suppressed, and the scale is dispersed in the form of amorphous fine particles, and the adhesion of the scale is prevented. Further, when the dissimilar electrode is installed outside the plastic pipe, static electricity is generated on the outside of the pipe due to friction between the plastic pipe and water passing through the inside, and a primary electric field is generated. A carbon electrode absorbs free electrons from an electrostatic field and distributes a high concentration of electrons around the electrode. On the other hand, aluminum electrodes emit free electrons into an electrostatic field. As a result, a high potential difference is generated between the two poles, and a thin-film secondary electrostatic field crossing the pipe at right angles is formed. Water is activated by receiving strong energy as it passes through this electrostatic field, preventing the formation of scale.

In the present invention, the silica removing apparatus is not particularly limited, but a column having an inlet and an outlet for water to be treated and packed with silica gel particles can be suitably used. There is no particular limitation on the silica gel used in the present invention.In addition to ordinary silica gel that is not chemically modified, methyl groups,
Silica gel chemically modified with hydrocarbon groups such as butyl, octyl, octadecyl, and phenyl groups, and silica gel chemically modified with ion-exchange groups such as amino, aminopropyl, quaternary ammonium, and sulfone groups Etc. can also be used. There is no particular limitation on the average particle size of the silica gel particles used in the present invention.
It is preferably 0 mm, more preferably 0.02 to 1 mm. The average particle size of the silica gel particles is 0.00
If it is less than 1 mm, a problem may occur in handling workability. If the average particle size of the silica gel particles exceeds 10 mm, the scale prevention effect may be reduced. There is no particular limitation on the shape of the silica gel particles, such as spherical, crushed, etc.
Silica gel particles of any shape can be used. The specific surface area of the silica gel particles is not particularly limited.
1,000 m ² / g, preferably 150 to 85
More preferably, it is 0 m ² / g. The pore size of the silica gel particles is not particularly limited, but is preferably 1 to 50 nm, more preferably 2 to 30 nm.

In the present invention, it is possible to treat the whole of the circulating cooling water by passing the whole amount of the circulating cooling water to the calcium carbonate modifying apparatus and the silica removing apparatus. However, in order to reduce the size of the apparatus, one of the circulating cooling water is used. It is preferred that the part be removed from the circulation line to the bypass line for processing and returned to the circulation line. In the present invention, by applying the calcium carbonate modifying means to the circulating cooling water system, the calcium carbonate scale component does not adhere to the wall surface and accumulates as particles suspended in water. Therefore, sludge can be removed by providing a weir in the pit of the cooling tower or by providing a filtration device, a settling tank, or the like in the cooling water circulation line. In the present invention, by providing a column filled with silica gel particles, the silica-based scale component in the cooling water precipitates on the surface of the silica gel particles, and the concentration of silica in the water decreases. Can be. According to the scale adhesion prevention method and prevention device of the present invention, by using a calcium carbonate modifying means and a silica removal device together,
Both the calcium carbonate scale obstacle and the silica scale obstacle that occur in the circulating cooling water system can be prevented at the same time without adding any chemicals.

[0012]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, which should not be construed as limiting the present invention. In Examples and Comparative Examples, the effect of preventing scale adhesion was evaluated using a circulating cooling water system having a pilot-scale heat exchanger. The cooling water system used had a water volume of 300 L and an outer diameter of 19 L.
0.3 mm heat transfer area with SUS304 tube
It has a 2 m ² heat exchanger. 40mg calcium hardness
/ L, tap water with an alkalinity of 50 mg / L and silica of 27 mg / L was used as makeup water, and the flow rate of the circulating cooling water was 4,180 L /
As h, a 12-fold concentration operation was performed for 30 days. The temperature at the heat exchanger inlet of the circulating cooling water is 30 ° C, and the temperature at the heat exchanger outlet is 5 ° C.
It was kept at 0 ° C. After 30 days, the tube of the heat exchanger was removed, dried at 105 ° C., weighed, and the scale deposition rate was calculated from the weight difference before and after the test. In addition, the collected scale was calcined at 600 ° C. for component analysis, and the amount of acid insolubles was represented as SiO _{2 and the} amount of calcium was represented as CaO. Example 1 A bypass line was provided upstream of a heat exchanger for circulating cooling water, a column filled with 70 kg of silica gel (Wako Pure Chemical Industries, Ltd., medium grain) and a permanent magnet [DNA.
Ltd., Mag Unit (1.5 inch nominal diameter)] were installed in this order, and circulating cooling water of 2,500 L / h was passed through the bypass line for 30 days of operation. The total scale deposition rate was 0.5 mcm (mg / cm ² / month), and the silica-based scale deposition rate was 0.3 mcm. Analysis of the scale components could not be performed due to the small amount of scale attached. Example 2 Instead of installing a permanent magnet, a solenoid coil type magnet [Triangular Wave Technologies, Deposit Control System TWT-5C-40]
Operation was performed for 30 days in the same manner as in Example 1 except that [2] was wound around the pipe of the bypass line. The total scale deposition rate was 0.6 mcm and the silica based scale deposition rate was 0.4 mcm. Analysis of the scale components could not be performed due to the small amount of scale attached. Comparative Example 1 The silica gel packed column in the bypass line was removed, the same permanent magnet as in Example 1 was installed, and polyethyleneimine (average molecular weight: 5,000) was added to the circulating cooling water at a concentration of 20 mg / L.
And operated for 30 days. The total scale deposition rate was 3 mcm, and the silica-based scale deposition rate was 1.9 mcm. The scale component was silica-based 63% by weight and calcium-based 23% by weight. Comparative Example 2 A 30-day operation was performed in the same manner as in Comparative Example 1, except that polyethylene glycol (average molecular weight: 8,000) was added so as to have a concentration of 20 mg / L instead of polyethyleneimine. The total scale deposition rate was 2 mcm and the silica scale deposition rate was 1.3 mcm. The scale component was 63% by weight of silica and 25% by weight of calcium. Comparative Example 3 The circulating cooling water was operated for 30 days without any treatment. The total scale deposition rate is 41 mcm,
The silica-based scale deposition rate was 5 mcm. The scale component was silica-based 11% by weight and calcium-based 78% by weight. The results of Examples 1 and 2 and Comparative Examples 1 to 3,
It is shown in Table 1.

[0013]

[Table 1]

As can be seen from Table 1, in Examples 1 and 2 using a silica gel packed column as a silica removing device, the silica-based scale adhered more than Comparative Examples 1 and 2 in which polyethyleneimine or polyethylene glycol was added. Few. It can be seen that by using a calcium carbonate denaturing means using a permanent magnet or a solenoid coil type magnet and a silica removing device comprising a silica gel packed column, it is possible to effectively prevent the adhesion of calcium carbonate scale and silica scale at the same time. .

[0015]

According to the method and apparatus for preventing scale adhesion of the present invention, the adhesion of calcium carbonate scale and silica scale can be simultaneously and effectively prevented in a circulating cooling water system without using any chemicals. Can be.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme court ゛ (Reference) C02F 1/46 C02F 1/46 Z 1/48 1/48 A 1/68 510 1/68 510G 520 520B 520K 520N 520S 520V 530 530A 540 540E 540F 5/02 5/02 B F28F 19/01 F28F 19/00 501A 501D 501Z (72) Inventor Tomio Kato 4-7 Nishishinjuku 3-chome, Shinjuku-ku, Tokyo Kurita Kogyo Co., Ltd. (72) Inventor Akira Iimura F-term (reference) 4D061 DA05 DB05 DB09 DC18 DC19 EA02 EA18 EB01 EB27 EB29 EB31 EB34 EC01 EC05 EC11 3-4-7 Nishi-Shinjuku, Shinjuku-ku, Tokyo

Claims (6)

[Claims] 1. A method for preventing scale adhesion, wherein circulating water is treated in a circulating cooling water system by a calcium carbonate modifying means and a silica removing device. 2. The method of claim 2, wherein the calcium carbonate modifying means is a magnetic treatment means for circulating water using a permanent magnet or a solenoid coil type magnet.
2. A combination of one or more selected from the group consisting of a means for dissolving metal ions into circulating water, a means for placing ceramic balls in circulating water, and a means for adding a seed crystal of calcium carbonate to circulating water. Scale adhesion prevention method. 3. The method according to claim 1, wherein the silica removing device is a column having an inlet and an outlet for the water to be treated and packed with silica gel particles. 4. A scale adhesion preventing device in a circulating cooling water system, comprising a calcium carbonate modifying means and a silica removing device. 5. A magnetic treatment means for circulating water by a permanent magnet or a solenoid coil type magnet, wherein the calcium carbonate modifying means is a permanent magnet or a solenoid coil type magnet.
5. A combination of at least one selected from the group consisting of a means for eluting metal ions into circulating water, a means for placing ceramic balls in circulating water, and a means for adding a seed crystal of calcium carbonate to circulating water. Scale adhesion prevention device. 6. The scale adhesion preventing device according to claim 4, wherein the silica removing device is a column having an inlet and an outlet for the water to be treated and packed with silica gel particles.