JP2003014189A - Method for peeling pipe inside deposit in boiler - Google Patents

Abstract

PROBLEM TO BE SOLVED: To facilitate maintenance and inspection, and to reduce costs, by dispensing with cleaning on the inside of a pipe and also to dispense with cleaning of a water service pipe, if this method is applied thereto. SOLUTION: The front end faces of iron pieces 4 and 4 facing each other are brought into contact with the pipe P, and an electromagnetic coils are installed to the pipes. Therefore, a magnetic field induced from the electromagnetic coil forms N and S magnetic polar pieces on the left and right sides, and minute electric current is let flow through the pipe P from the electromagnetic coil. In this way, the magnetic field is generated inside the pipe by means of the magnetic poles N and S, and by the magnetic field, magnetic lines of force with a magnetic flux density B are generated. When a water solution with a flow speed V passes the magnetic lines of force, an electric current i flows along the pipe wall according to the Faraday's law of induction. Therefore, electrolysis is caused by the current i between the pipe wall and the deposit and induces multiplier effect with a pipe inside deposit decomposing action, and consequently, the deposit is peeled off gradually.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to, for example, a boiler and its piping, piping for a heating device such as a condominium, piping for cooling a cooling tower, and scales generated in an aqueous solution in a piping for supplying regional steam in a city. The present invention relates to a method for peeling off a product adhering to a pipe for peeling a product adhering to an inner wall, and also includes peeling off the product adhering to the pipe and preventing the product from adhering to the inner wall of the pipe.

[0002]

2. Description of the Related Art Conventionally, for example, water stains or products called scales are accumulated in boilers and pipes, and in water pipes of condominiums, which impedes the flow of aqueous solutions. Therefore, it was necessary to regularly remove this product.

As a conventional example for removing them, the first is a method of cleaning with an acid solution containing a corrosion inhibitor (for example, JP-A-56-2897, JP-A-52-82639 and JP-A-54). No. 117327), the second is a method of removing the scale on the inner surface of the pipe wall by mixing pellets made of a material having a specific gravity close to that of water into the circulating water (for example, JP-A-52-5).
No. 3544) and thirdly, the scale of the pipe wall is peeled and removed by changing the circulating water and the flow velocity without using chemicals or pellets and utilizing the difference in the expansion coefficient between the pipe wall and the scale (for example, JP-A-52-28253, JP-A-54-5
No. 104) is known.

Further, as a fourth conventional example, an electric field and a magnetic field are applied from the outside of the boiler to prevent local corrosion of the pipe, and the circulating water is softened by a magnetic action to remove the scale adhering to the pipe wall. What causes (for example, Patent No. 121
5830), the technical point of this device is to change the crystal structure of CaCO ₃ contained in the circulating water from argonite to calcite by magnetic action.
It is to make the scale smaller and peel it off.

[0005]

In the first to third conventional examples, the operation of the boiler and the cooling tower is stopped and the products adhering to the inner wall of the pipe and the products in the circulating water are removed. It costs money. Further, in any of the above-mentioned conventional examples, in order to take out the scale that has been peeled off after regularly cleaning the inside, a great deal of cost and time are required for maintenance. Further, in the fourth conventional example, the product attached inside the pipe is not separated by the action of the electromagnetic field.

Therefore, an object of the present invention is to facilitate maintenance and inspection by eliminating the need for cleaning the inside of the pipe, and to reduce the cost. When applied to a water pipe or a cooling tower, the cleaning is unnecessary. Another object of the present invention is to provide a method for removing adhered products in a pipe, which is applied to a boiler or the like to prevent reduction in thermal efficiency of the boiler or the like.

[0007]

In order to achieve the above-mentioned object, the feature of the method for removing adhered products in a pipe of a boiler or the like according to the present invention according to claim 1 is that the products are produced in an aqueous pipe solution and If a leak magnetic field exists inside the pipe due to an electromagnet attached to the outside of the pipe and the magnetic flux generated from this leak magnetic field is cut off by the aqueous solution of the pipe, the flow of the aqueous solution is perpendicular to the flow of the aqueous solution due to Faraday's law of electromagnetic induction. A Lorentz force is generated along the pipe wall in the direction, and the effect of this Lorentz force is that the adhered products can be separated by the external magnetic field of the electromagnet mounted outside the pipe.

The features of the present invention described in claims 2 and 3 are as follows:
Attach a ground wire along the pipe from a device that mounts an electromagnet on the outside of the pipe to make it easier for current to flow along the pipe, and the current from this ground wire flows along the pipe wall, and this is caused by the law of electromagnetic induction. Since the electric current that flows along the tube wall also increases, the current that flows along the tube wall increases, and the amount of electrolysis also increases, which promotes the separation of the products adhering to the tube wall. is there.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION First, the scientific basis of a product containing ferromagnetic ultrafine particles generated in an aqueous solution of a boiler and piping will be described.

In FIG. 1, which shows an outline of a boiler, steam is generated in a combustion chamber 1, and the steam generated is a pipe P1.
The steam is separated into steam and water in the heat exchanger 2, and the steam is sent to a predetermined place by a predetermined means by the pipe P2, consumes heat and returns to the combustion chamber 1.
Further, the water and part of the steam return to the combustion chamber 1 through the pipe P3. Water lost in the circulation process is supplied to the combustion chamber 1 through the supply pipe P4. In this circulation process, products containing ferromagnetic ultrafine particles are generated on the inner walls of the pipes P1, P2, P3.

To briefly describe the process of this generation, tap water is usually used as the steam generated in the combustion chamber 1. In this tap water, CaO, MgO, and Si are generally used.
It contains compounds such as O ₂ . When the boiler is operating, steam disappears and supply is repeated, resulting in C
The concentration of a ²⁺ and Mg ²⁺ gradually increases, and CaO and Mg
Compounds such as O also increase. Further, the pipes P1, P2 and P3 are galvanized to prevent corrosion, but the zinc plating is peeled off and a ZnO compound is also present. Further, since the combustion chamber 1 and the pipes P1, P2, P3 are made of iron, they are gradually corroded to form ferric hydroxide [Fe (OH) ₂ ] and ferric hydroxide [Fe (OH) ₃ ]. Settle. During the course of this reaction, the aqueous solution becomes alkaline with a pH of 9.5-11.0.
At this time, ferric hydroxide [Fe (OH) ₂ ] and ferric hydroxide
[Fe (OH) ₃ ] is further oxidized and ionized Fe
^{2+, Fe 3+} is co-precipitation in an alkaline aqueous solution, ferromagnetic ultra-fine particles of magnetite _[Fe 2 _{O 3]} is generated.

Next, as shown in FIG. 2 which shows a cross section of a used pipe used in a boiler or the like, the hollow portion in the steel pipe material portion (steel) of the pipe P has a product produced by corrosion of the pipe. A portion D (hereinafter referred to as a "lower layer portion") that is attached near the surface (the actual product is dark brown) and a surface U (hereinafter referred to as the "upper layer portion") to which the product (the actual product is brown) is attached. Can be roughly divided into parts. Table 1 shows the results of measurement of the content of each component element contained in the deposition products of the lower layer portion D and the upper layer portion U using a fluorescent X-ray analyzer.

[0013]

[Table 1] From Table 1, Fe compounds account for about 90% of the main components of the deposition products of the lower layer D and the upper layer U, and Zn, Ca, C
Compounds such as u and Si were found. The components of the scale represent the whole of the deposited product. Z on the scale
A large amount of nO is caused by corrosion of the zinc plating applied to the steel pipe P, and the lower layer portion D is contained more than the upper layer portion U.

FIG. 3 shows the scale of the deposit product in the pipe P,
The result of having measured the product phase of each part of lower layer part D and upper layer part U, and their content by X ray analysis was shown.
In the steel pipe P, the upper layer portion U, and the lower layer portion D of FIG. 3, C is Ca
lcite and S show spectra in agreement with the Spinel type crystal structure. The strongest spectrum on the scale of the sample of the steel pipe P indicates that it contains Fe ₂ O _{3 which} is a ferromagnetic ultrafine particle having a Spinel type structure. The strongest spectrum of the upper layer S and the lower layer U is Fe ₂ O ₃ .

FIG. 4 shows the measurement results of the magnetizations of the upper layer portion U and the lower layer portion D of the deposit product in the pipe. The magnetization curves of both the upper layer portion U and the lower layer portion D show a hysteresis, and the magnetization curve is about 10 KOe. The above magnetic field shows a tendency to be almost saturated. The magnetization value of the lower layer portion D is 55 emu / g.
Thus, it is slightly higher than 48 emu / g of the upper layer portion U. It is considered that this is because the lower layer portion D contains a large amount of ferromagnetic ultrafine particles Fe ₂ O ₃ .

The specific structure and operation of the peeling device will be described below based on the above results. First, with reference to FIGS. 5 to 7, a structure and a peeling operation of a peeling device 10 for a product containing ferromagnetic ultrafine particles of a product deposited in a pipe will be described.

In FIG. 5, soft iron pieces 4 and 4 which are magnetic adjusting pieces are attached to the tip of the core 3 so as to face each other, and the arcuate surface of the tip of this piece is in contact with the pipe P and is attached to this piece. Is equipped with electromagnetic coils 5 and 5. for that reason,
The magnetic field induced from the electromagnetic coil 5 constitutes N and S pole pieces on the right and left sides. A lead wire is connected to the pipe from the electromagnetic coil 5 so that a weak current is passed through the pipe.
Therefore, when the electromagnetic coil 5 is mounted on the outside of the pipe P and the soft iron piece 4 is also mounted as described above, a magnetic field is generated in the aqueous solution in this pipe. When the aqueous solution cuts the lines of magnetic force generated from this magnetic field, a current flows along the wall due to the electromagnetic induction of Faraday.

Further, in FIG. 6, when the outer electromagnetic coil 5 of the pipe P is attached, a magnetic field is generated in the pipe by the magnetic poles N and S, and the magnetic field generates a magnetic force line having a magnetic flux density B. When the aqueous solution of V is cut off, a current i flows along the tube wall according to Faraday's law of electromagnetic induction. Therefore, this current i causes electrolysis between the tube wall and the deposit product, and induces a synergistic effect with the decomposition action of the deposit product in the pipe. At this time, Lorentz force F = qV
Since B acts, the adhered product is peeled off little by little.

Further, when the aqueous solution in the pipe P is circulating, the aqueous solution in the pipe becomes alkaline due to corrosion of the pipe and the like, and the pH value is alkaline of 9.5 to 11.0, and the aqueous solution is H.
₂ O → ^H + + OH ^- and ionized, ^{H +} and ^{Fe 2+} (piping)
The magnitude of the ionization tendency of Fe ²⁺ > H ⁺ . Since the amount of the deposit products that are electrolyzed increases by inducing a synergistic effect with the stripping action that occurs due to the electrolysis that occurs when the current that flows from the difference in the ionization tendency flows in the direction of the tube wall, the deposits that are stripped are also increased. The amount of product also increases. Further, when the aqueous solution in the pipe P is circulating, the aqueous solution in the pipe becomes alkaline due to corrosion of the pipe and the like, and the pH value is 9.
Alkaline from 5 to 11.0, the aqueous solution is H ₂ O → H ⁺ + OH
^- it is ionized with. Although this H ⁺ ion is not a metal ion, it is in the ionization train where it is ionized to become a cation, and the magnitude of the ionization tendency of H ⁺ and Fe ²⁺ (pipe) is Fe ²⁺ > H ⁺ . Iron atoms release electrons and oxidize. On the other hand, the hydrogen atom in the aqueous solution receives an electron and is reduced, and a simple hydrogen H is produced. Therefore, iron is more likely to become a cation than hydrogen. As a result, the aqueous solution becomes the anode and iron becomes the cathode, and the current i flows from the aqueous solution to the pipe.
Flows. This current i caused by the difference in ionization tendency easily flows along the pipe, and flows in the same direction as the current i generated by electromagnetic induction.

As described above, since the H ⁺ ions have a smaller ionization tendency than Fe ²⁺ > H ^{+ as} compared with the iron ions in the pipe, the aqueous solution becomes the anode and the pipe becomes the cathode, and the aqueous solution becomes the cathode wall of the pipe. When the current flowing along the line and the aqueous solution flowing in the pipe cut the line of magnetic force generated by the leakage magnetic flux, the current generated according to the law of electromagnetic induction is added to induce a synergistic effect. As a result, the amount of the flowing current i further increases, and the amount of the adhered product that is electrolyzed by inducing a synergistic effect with the peeling action caused by the electrolysis caused by the flow of this current also increases. The amount of deposited product that is removed also increases.

FIG. 7A shows the relationship between the magnetic field (lines of magnetic force), the electric current, and the force (Lorentz force) to be applied according to Faraday's law of electromagnetic induction. As shown in FIG. 6, magnetic force lines of magnetic force density B are generated from the N pole to the S pole,
At this time, the direction of the current i is perpendicular to the lines of magnetic force. This causes the current i to flow along the pipe. Further, the direction of the Lorentz force F at this time is perpendicular to the direction of the current. FIG. 7B shows this state with the left hand.
FIGS. 7A and 7B show the law of electromagnetic induction, which is called Fleming's left-hand law.

FIG. 7B shows the relationship between the magnetic field (direction of magnetic force lines) generated by electromagnetic induction of Faraday, the direction of current flow at that time, and the Lorentz force F (force received) at that time, which is represented by the index finger, the middle finger, It is expressed using the thumb, that is, Fleming's left-hand rule, in which the index finger indicates the direction of the magnetic field line B, the middle finger indicates the direction of the current i, and the thumb indicates the direction of the Lorentz force F.

By using the peeling device according to the present invention, the products adhering to the pipes of the boiler, the heating device, the cooling tower, etc. can be peeled and removed. In order to prove this peeling effect more concretely, an experimental device was used. It was created and the peeling effect was measured.

FIG. 8 shows an experimental apparatus for magnetically peeling the product deposited in the pipe. A galvanized steel pipe Pa, which has been used for about 5 years and is the same as that shown in FIG. 2, is attached to the device, and a peeling device 10, a flow meter 11, and a tank 12 corresponding to the combustion chamber 1 of FIG. The recovery device 13 is attached, the aqueous solution is collected from the boiler being used, and the aqueous solution is circulated by the pump 14.
The flow rate is 2 h / m ² .

FIG. 9 shows the results of an experiment conducted for 8 weeks for the experimental apparatus of FIG. 8 with the peeling apparatus 10 attached and the case where the peeling apparatus 10 is not attached. First one
It is considered that the peeling of the adhered product progressed with and without the peeling device 10 in the week, that the surface of the adhered product was peeled by the water flow. From the second week onward, the amount of peeling decreases when not worn, whereas the amount of peeling decreases when wearing the wearer from the second to third weeks. This is due to the action of the electromagnetic field. It takes some time for the product to loosen and peel off, but from the 3rd week to the 4th week, it is understood that the peeling progresses. This tendency is the same as in the 8th week.

FIG. 10 is a summary of the peeled amount in 8 weeks of FIG. 9, and the peeled amount increased by about 4 times when the peeling device 10 was attached compared to when it was not attached. As a result, the peeling device 1
The effectiveness of wearing 0 was found.

[0027]

From the results shown in FIGS. 9 and 10, according to the present invention,
Since the adhered products of the boiler and the like can be peeled off and removed, cleaning and the like of the boiler and the like can be performed while operating, so that regular maintenance can be simplified and the maintenance cost of the boiler and the like can be reduced. Further, since the adhesion of the product is reduced, it is possible to prevent a decrease in the thermal efficiency of the boiler and the like and facilitate cleaning. As a result, the cost required for peeling and removing the product can be reduced. In particular, in the present invention, the peeling and removal of the product can be controlled by an external magnetic field, and the peeling operation can be performed automatically. Of course, if this stripping device is mounted on the pipe from the beginning, the product can be prevented from adhering to the pipe.

[Brief description of drawings]

FIG. 1 is a schematic diagram of a boiler.

FIG. 2 is a sectional view of piping.

FIG. 3 is an X-ray diffraction diagram of a deposited product.

FIG. 4 is a graph showing the magnetization curves of the lower layer portion and the upper layer portion of the attached product.

FIG. 5 is a cross-sectional view of a peeling device.

FIG. 6 is a cross-sectional view showing the action of an electromagnet.

FIG. 7 is a perspective view showing Faraday's law of electromagnetic induction.

FIG. 8 is a perspective view showing an experimental device.

FIG. 9 is a graph showing changes in the amount of scale peeling.

FIG. 10 is a graph showing the ratio of the total amount of scale and the amount of peeling.

[Explanation of symbols]

1 combustion chamber 2 heat exchanger 3 core 4 Magnetic adjustment piece (soft iron piece) 5 electromagnetic coil 10 Peeling device 12 tanks 13 Magnetic recovery device P piping P1 piping P2 piping P3 piping P4 piping Pa piping Lower part of D product Upper part of U product

Front page continuation (51) Int.Cl. ⁷ Identification code FI theme code (reference) C02F 1/48 C02F 5/00 610A 5/00 610 610B 620B 620 620D F22B 37/52 Z F22B 37/52 F28G 13/00 Z F28G 13/00 B08B 9/02 Z F term (reference) 3B116 AA12 BB89 BC00 3B201 AA12 BB89 BB92 BC00 3H024 DA10 4D061 DA05 DB05 EA02 EB02 EC02 EC05 EC19

Claims (3)

[Claims] 1. An electromagnet for generating a leakage magnetic field in the pipe is provided on the outer peripheral portion of the pipe in which the aqueous solution such as water or steam flows, so that the aqueous solution flowing in the pipe is protected from the leakage magnetic field generated in the pipe. When the generated lines of magnetic force are cut, the Lorentz force generated by the electromagnetic induction of Faraday and a current accompanying it flow, the peeling action on the deposit products in the pipe due to the action of the Lorentz force, and the current flows along the pipe wall of the pipe. The flow of electricity causes electrolysis between the pipe wall and the deposition product to induce a synergistic effect with the decomposition action of the deposition product in the pipe, and the deposition product in the pipe is peeled off. A method for removing adhered products in piping such as boilers. 2. An aqueous solution in the pipe flowing in the pipe is generated in the pipe by equipping an outer periphery of the pipe in which the aqueous solution such as water or steam flows with an electromagnet for generating a leakage magnetic field in the pipe. When the line of magnetic force generated from the leakage magnetic field is cut, an electric current flows along the pipe wall according to Faraday's law of electromagnetic induction, and this current causes electrolysis to decompose the products adhering to the pipe and corrode the pipe, resulting in the above aqueous solution. Becomes an alkaline electrolyte, and this aqueous solution is ionized as H ₂ O → H ⁺ + OH ^−, and the ionization tendency of H ⁺ and Fe ²⁺ is Fe ²⁺ > H.
⁺ , And the current caused by the difference in ionization tendency is H ⁺ → F
Since it is in the direction of e ²⁺ , a boiler is characterized in that it induces a synergistic effect with a peeling action caused by electrolysis caused by flowing in the direction of the pipe wall, and further promotes the peeling of the adhered product on the pipe wall. How to remove products attached to piping such as. 3. An aqueous solution in the pipe flowing in the pipe is generated in the pipe by equipping an outer periphery of the pipe in which the aqueous solution such as water or steam flows with an electromagnet for generating a leakage magnetic field in the pipe. When the line of magnetic force generated from the leakage magnetic field is cut, a current generated from the law of Faraday electromagnetic induction flows along the pipe wall, and this current causes electrolysis to cause the decomposition action of the adhered products in the pipe and the corrosion of the pipe. The aqueous solution becomes an alkaline electrolyte, and this aqueous solution is ionized as H ₂ O → H ⁺ + OH ^−, and H ⁺ ions have an ionization tendency of Fe ²⁺ > H ⁺ compared to iron ions in the pipe, so the aqueous solution serves as an anode. The pipe becomes a cathode, and when the current flowing from the aqueous solution along the pipe wall of the pipe and the magnetic flux generated by the leakage magnetic field in the aqueous solution flowing in the pipe are cut off, electromagnetic waves are generated. Subjected to any current generated by the law of electrically inducing a synergistic effect, method of removing piping deposition products, such as boilers, characterized by further promoting the separation of the pipe attachment product by these currents.