JPH0639395A - Method for preventing scale from adhering - Google Patents

Abstract

PURPOSE:To obtain a method for preventing efficiently scale from adhering by investigating the optimum range where the amt. of adhesion of the scale is decreased in a region of high magnetic flux density. CONSTITUTION:In a part of the path in an apparatus using industrial water under circulation condition, passing water stream is accelerated to at least 0.5m/sec and a magnetic field with a magnetic flux of 12,000-15,000 Gs is applied to prevent a hardly soluble substance wherein calcium carbonate and silicic acid are main ingredients from adhering as a scale. As the result, the amt. of adhesion of the scale can be remarkably decreased.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a circulating water for an industrial apparatus such as a cooling system, a boiler and a heat exchanger for circulating industrial water and a method for treating feed water, and a scale attached to a part of the apparatus. To effectively prevent water leakage, simplify maintenance management, and keep circulation water normally with a minimum amount of blow in the circulation system, and enable effective use of supply water in water supply. Regarding

[0002]

2. Description of the Related Art Since industrial water used in devices such as cooling systems is prevented from generating scales when it passes through a magnetic field, magnetic treatment devices have been reported for them. Showa 52-112115, Showa 58-
108156, JP-A-61-118187 and the like.
According to these reports, since permanent magnets and electromagnets ionize sparingly soluble impurities in water to promote dissolution in water,
The anti-scaling effect of the magnet is said to be proportional to the strength of the magnetic field. However, in a magnetic treatment device that passes water through a magnetic field, the strength of the magnetic field is limited by the diameter of the pipe to which the magnet is attached, and in a device that passes water around the magnetic field, the structure becomes complicated and the flow velocity of water is reduced. Effective magnetic treatment is difficult because it cannot be sufficiently raised. Therefore, although the magnetic flux density is preferably 8000 Gs or more, it is extremely difficult to produce an electromagnet having such a magnetic flux density, and the experimental data is up to 8000 Gs because it is unsuitable as an industrial product. Moreover, in this range, the optimum magnetic flux density for preventing scale has not been found, and the magnetic field dependence depending on the type of ions has not been confirmed.

[0003]

SUMMARY OF THE INVENTION The present inventor has made the above-mentioned 8000 Gs by making a compact and strong electromagnet.
Researching the effect of scale prevention in the above range,
The inventors have completed the present invention by discovering that there is a specific optimum magnetic flux density that can very effectively prevent scale adhesion in the high magnetic field, and that it depends on the type of ions.

[0004]

The present invention provides 8000 Gs
Desirably, a scale in a high magnetic field of 10,000 Gs or more
In order to prevent this, we have created a compact and powerful electromagnet that realizes the high magnetic field. The outline is that an electromagnet is used, the magnetic lines of force are closed by an inner iron core and an outer iron core, treated water is caused to flow in a gap between magnetic poles, and an exciting coil is provided between the iron cores. (A) The cross-sectional area of the inner iron core and the surface area of the tip of the magnetic pole are 1.5 times or more to prevent the magnetic flux induction from being distorted when the magnetic force lines generated in the inner iron core face the magnetic pole. The magnetic flux density is maintained at a high density, and (b) the squeezing angle between the magnetic pole tips of the inner iron core and the outer iron core is set to 54 ± 5 ° to prevent the magnetic force lines from becoming saturated at the magnetic pole tips. It is configured to concentrate the magnetic path toward the main magnetic field near the corner to obtain the highest density.

Next, in order to investigate the solubility and the magnetic field dependence of calcium carbonate, which is the main component of the scale, in water,
Sodium silicate was purified by dissolving pure calcium hydroxide and reacting it with carbon dioxide to prepare an aqueous solution of calcium hydrogen carbonate. Similarly, in order to investigate the solubility and magnetic field dependence of the silicate scale, sodium silicate was purified. Melted into These aqueous solutions
In the above electromagnet apparatus, magnetic treatment was performed while changing the magnetic flux density while circulating at a flow rate of 10 l / min for 4 hours, and the scale adhesion amount was measured.

The results are shown in Table 1, and the weight of the calcium carbonate scale reaches a maximum value near 5000 Gs, but thereafter decreases as the magnetic flux density increases, and
It decreases to less than 1/3 of the maximum value near 000 Gs. On the other hand, the scale adhesion weight in the system to which silicic acid is added is
The higher the magnetic flux density is, the smaller the scale amount becomes.
It shows a minimum value near s, but thereafter shows a tendency to increase again. From this result, it has been proved for the first time that the scale adhesion amount does not decrease simply by increasing the magnetic flux density, but that the optimum magnetic flux density exists depending on the kind of the component contained in water.

[Table 1]

Further, in order to study the interaction between the above-mentioned calcium carbonate and silicic acid alone, and not the dependence on the magnetic field, tap water containing both components of calcium carbonate and silicic acid was used. Under the same conditions as above, the change in the amount of scale attached with the change in magnetic flux density was measured. The results are as shown in Table 2, and the amount of adhesion becomes maximum around 5000 Gs, and then decreases with an increase in magnetic flux density.
Around 000Gs, it decreased to less than 1/3 of the maximum value, 135
The minimum value was shown near 00 Gs. Then, after that, it showed an increasing tendency, and the amount of adherence increased to about the same value as the previous value of 12000 Gs at around 15000 Gs, and even if the magnetic flux density was further increased, the burden on the device was only increased and no effective result was obtained. . As a result, when both the components of calcium carbonate and silicic acid are present, the scale deposition amount decreases with the increase of the magnetic flux density theoretically up to around 10,000 Gs,
It has been found that there is a minimum point over 10000 Gs, especially around 135000 Gs, and the scale adhesion amount can be critically suppressed to 1/3 or less of the maximum value in the range of 12000 to 15000 Gs.

[Table 2]

Therefore, the scale prevention method of the present invention is intended for a liquid containing a sparingly soluble substance containing calcium carbonate and silicic acid as main components, and its magnetic flux density is from 12000 to 1500.
A magnetic field is applied in the range of 0 Gs to prevent the occurrence of scale under the influence of an electric field in a certain range.
Further, since the generation of the electric field is related to the strength of the magnetic field and the velocity of the passing water, it is not effective at an excessively slow velocity, and is effective when accelerated to 0.5 m / sec or more.

To examine the reason why the critical optimum range exists, calcium carbonate is divided into calcium ion Ca ²⁺ and carbonate ion CO ₃ ^{2− in} a solution, which is the magnetic flux density of the magnetic field. When it is increased, water containing ions passes through the high magnetic flux density, so that a stronger electric field is generated and the scale adhesion amount is proportionally reduced. On the other hand, silicic acid has silicate ions SiO ₃ ^2- , but when the magnetic flux density is increased,
The adhered amount decreases up to a certain minimum point, but after that, the tendency tends to increase, and the strength of the electric field is not necessarily proportional to the adhered amount. This indicates that the influence of the electric field differs depending on the type of ions passing through, and is considered to be one factor for the existence of the critical range.

In order to find out the reason why the above critical range appears,
The relationship between the Si / Ca molar ratio in the scale and the magnetic flux density in the case where calcium carbonate and silicic acid coexist was determined.
The results are shown in Table 3, and when the magnetic flux density is gradually increased from 8000 Gs, Si / Ca is proportionally increased.
However, even if the magnetic flux density is further increased, there is almost no increase in the molar ratio. The reason for this is that when the silicate ions are activated by the magnetic field, they can be bound by the silicic acids in the scale, and the bound silicic acid simply loses the tentacles for binding to other substances. This is because it changes to a bulky form without causing steric hindrance that hinders access to scaled ions. For this reason, an increase in the ratio of silicate ions exerts the effect of preventing scale, and even in the case of scaling, a scale state in which peeling is very easy occurs. From Table 3 to 12000 Gs, it can be seen that the tentacles of the bond of silicic acid remain, and if it is more than this, the effect due to the magnetic flux density is small, so even if the magnetic flux density is increased to 15000 Gs or more, the effect just increased is expected. Can not.
This tendency is also supported by the relationship between the silicate scale weights in Table 1.

[Table 3]

Further, the above-mentioned calcium carbonate and silicic acid are
If they exist, they will dissociate as ions,
Interaction with each other, Ca of calcium carbonate²⁺With ion
CO 3^2- After dissociation into ions progresses, silicate ions Si
O₃ ^2-When I met him, he became a salt of calcium silicate, which
Has a high probability of becoming a water-insoluble scale, which is shown in Table 2.
Optimal in the range of 12000 to 15000 Gs as shown in
It is considered to be one of the factors showing the value.

According to the present invention based on the above-mentioned structure, in an apparatus such as a cooling system that circulates industrial water, the scale adhesion amount is minimized in a region of high magnetic flux density which has never been seen before. The range can be found critically, and the scale adhesion can be greatly reduced as compared with the conventional case, which is a very remarkable effect.

[0012]

[Example 1] The flow velocity of water in the pit of the cooling tower was 1
After the magnetic flux density was changed in the range of 3000 to 16000 Gs under the condition of circulating at 1 l / min for about 100 hours, the amount of scale attached to the heat exchanger was examined.
The results are shown in Table 4 below. At 13500 Gs, the scale adhesion showed a minimum value of 3% with respect to the non-treatment.
The adhesion rate was suppressed to 6% or less in the range of 000 to 15,000 Gs.

[Table 4]

[0013]

Example 2 As a groundwater treated with a magnetic flux density of 13000 Gs, the boiler was operated for 50 hours at a working pressure of 7 Kgf / cm ^2. As a result, untreated groundwater had a very hard scale attached to its entire surface, but magnetic treatment. When using water,
Although the scale was slightly attached, the scale was soft in nature and could be easily removed. Next, Table 5 shows a part of the analysis results of raw water, untreated boiler water and magnetically treated boiler water.
Shown in. As is clear from Table 5, the hardness component in the untreated boiler-water is about 250 (mg / l) when calculated from the concentration multiple based on silicic acid, but the measured hardness value is the measurement limit. It is the following. Most of the hardness is boiler
It means that the water was attached to the boiler as a scale, but the hardness of the magnetically treated boiler water was observed, and the scale preventive effect of the magnetic treatment was clearly proved.

[0014]

[Table 5]

Claims (2)

[Claims] 1. A part of a path of an apparatus for circulating industrial water is used to accelerate a passing water flow to 0.5 m / sec or more and to have a magnetic flux density of 12,000 to 15,000 in the water flow.
A method of preventing a hardly soluble substance containing calcium carbonate and silicic acid as main components from adhering as a scale by applying a magnetic field of Gs. 2. The scale adhesion preventing method according to claim 1, wherein the magnetic flux density is 13500 Gs.