JPH05280889A - Cleaning ball - Google Patents

Abstract

PURPOSE:To delete slime, etc., adhered to an inner surface of a heat transfer tube without cutting OFF a protective film by adhering a particulate abrasive having special hardness and particle size on a surface of a spongy rubber sphere having continuous bubbles and softness of the degree which can pass the tube while in contact with the inner surface of the tube. CONSTITUTION:The cleaning ball comprises a spongy rubber sphere 1 having an outer diameter slightly larger than an inner diameter of a heat transfer tube, continuous bubbles and softness to pass the tube while in contact with the inner surface of the tube by cooling water flow, and a particulate abrasive 2 adhered to the surface of the sphere. The abrasive 2 has hardness of JIS A 50-90 to be formed of a material such as, for example, natural synthetic rubber, synthetic resin, elastomer, etc., and a particle size of the degree in which a surface of the sphere 1 can be formed to be rugged by adhering it and generally a particle size of about 0.3-2.0mm. Thus, the ball which has excellent cooling efficiency and does not cut OFF an iron protective film of an inner wall of the tube.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cleaning ball used in a device for cleaning an inner wall of a heat transfer tube in a tube heat exchanger, and particularly suitable for a heat transfer tube made of a copper alloy.

[0002]

2. Description of the Related Art In heat exchangers used in condensers or air-conditioning equipment in power plants, etc., due to the adherence of slime, algae, etc. in the heat transfer tubes of the tubular heat exchanger through which cooling water passes, The heat exchange efficiency may decrease. For this reason, the inside of the heat transfer tube has been conventionally cleaned, and as a typical cleaning method, a cleaning body that is easily deformed slightly larger than the inner diameter of the heat transfer tube, for example, a sponge rubber ball, is forced into the heat transfer tube. A method is known in which the scale and the like adhering to the inner wall of the pipe are removed by continuous passage. The cleaning body used in this method is usually made of a sponge rubber material having open cells so that the cleaning body easily moves with the water flow and the water sufficiently penetrates (Japanese Patent Laid-Open No. 58-210500).

However, if the sponge rubber material alone is used, it is difficult and difficult to remove if the amount of slime is large or if the slime is hard. To improve cleaning efficiency, sponge balls are coated with hard particles such as synthetic resin and carborundum (Jitsuko Sho-45-
No. 30242, and Japanese Utility Model Laid-Open No. 60-81493) are proposed.

[0004]

By the way, the heat transfer tube is
Copper alloy pipes are used to improve thermal conductivity, but when cooling water is seawater, it is controlled so that a protective iron film is formed on the inner wall surface of the pipes to prevent corrosion.
In general, a protective coating can be formed on the inner wall of a pipe by injecting a small amount of ferrous sulfate into seawater.

This protective coating is provided when the cleaning balls passing through the heat transfer tube during cleaning are made of sponge rubber alone.
Although it is not largely consumed, the sponge rubber material alone is severely worn out as described above, but the slime removing efficiency in the pipe is small and time-consuming. On the other hand, for the purpose of improving the removal efficiency, use of a sponge ball coated with a hard synthetic resin, or use of a carborundum coated for removal of hard slime is also proposed as described above. However, in this case, the protective film mainly composed of iron is scraped off by the polishing action of the hard synthetic resin or the carborundum, which causes a problem that the inner surface of the heat transfer tube is locally eroded.

For this reason, there has been a strong demand for a cleaning body which has high wear resistance and is excellent in the efficiency of removing slime in the pipe, and yet does not damage the protective coating on the inner wall of the pipe by iron. ..

The present invention has been made in view of the above circumstances, and an object thereof is to provide a cleaning ball which has good cleaning efficiency and does not scrape off the iron protective coating on the inner wall of the heat transfer tube.

[0008]

The feature of the cleaning ball of the present invention made to achieve the above object is that it is a cleaning body for cleaning the inner surface of the heat transfer tube of the tubular heat exchanger. This cleaning body is composed of sponge rubber spheres having a slightly larger outer diameter and having a softness that allows passage through the inner surface of the heat transfer tube while being in contact with the cooling water flow, and a granular abrasive adhered to this surface. Moreover, the granular abrasive has a hardness of JIS A50 to 90 made of, for example, natural synthetic rubber, synthetic resin, or elastomer, and the surface of the sponge sphere is made uneven by the adhesion thereof. Particle size to the extent possible, generally 0.3-2.
It has a particle size of about 0 mm.

The iron protective coating provided to prevent corrosion of the heat transfer tube cannot be made so thick as to improve heat transfer efficiency, and if a hard synthetic resin or the like is attached to the surface of the cleaning ball, it will be scraped off. Use of the above-mentioned JIS A50-90, preferably 60-80, range of granular abrasives of the present invention makes it possible to obtain the same slime removal efficiency as the synthetic resin, without the protective coating being scraped off. ..

The life of the cleaning ball can be extended by changing the hardness of the rubber material depending on the slime condition.

The particle size of the granular abrasive also affects the removal of slime. That is, the slime on the inner wall of the pipe floats in the cooling water as dust after passing through the cleaning ball and flows out together, but a part of the slime moves along with the clogged ball between the granular abrasives on the surface of the cleaning ball. Therefore, the particle size is preferably 0.3 to 2.0 mm, and preferably 0.5 to 1.
It is 0 mm. When it is 0.3 mm or less, when the cleaning ball is adhered to the surface of the cleaning ball, it is buried in the adhesive and the performance of removing slime deteriorates. On the other hand, if it is 2.0 mm or more, the particles are excessively projected on the surface of the cleaning ball and the frictional resistance with the inner wall of the tube is increased so that the particles do not flow smoothly, and it becomes difficult to hold the particles with an adhesive and the particles fall off. If the adhesive layer is thickened to securely hold the particles in order to prevent the particles from falling off, the adhesive layer serves as a preventive film to prevent water from penetrating into the sponge balls, resulting in a lighter specific gravity.
If there is a free water surface inside the device, the cleaning balls will float and float on the water surface, which will prevent smooth passage to the heat transfer tubes.

[0012]

EXAMPLES The present invention will be described below based on examples.

FIG. 1 is a sectional view of the cleaning ball of the present invention, FIG.
Is an enlarged view of the surface portion of the present invention, FIG. 3 is a cross-sectional view of a sponge rubber ball of a comparative example which is not coated with a granular abrasive, and FIG. 4 shows a heat transfer tube wear device.

Example 1. (1) The concentration of chloroprene adhesive (Cemedine 570 (made by Cemedine)) was adjusted to about 10% on the surface of an open-cell sponge made of natural rubber having an outer diameter of 24 mm and an apparent specific gravity of 0.25 by using an organic solvent. Apply once.

(2) Vulcanized rubber having a hardness of JIS A72 shown in Table 1 below is crushed to a particle size of 0.7 to 1.0 mm.
The rubber particles adjusted in step 1 are attached to the whole and dried.

(3) The adhesive used in (1) above is applied twice thereto and dried.

(4) Heat treatment is performed at 100 ° C. for 30 minutes.

The cleaning balls that had undergone the steps (1) to (4) had good water permeation into the balls. This has an outer diameter of 25.
A heat transfer tube with an inner wall of a copper alloy tube of 4 mm and a length of 2 m coated with iron was installed in a device (Fig. 4) in which cleaning balls flow with water, and three cleaning balls are passed continuously at a speed of 2 m / sec for 30 hours. The test was repeated. The state of wear of the iron protective coating was observed and is shown in Table 4.

[0019]

[Table 1]

Example 2. The granular abrasive material has a hardness of JISA85 shown in Table 2 below and a rubber particle size of 1.0 to 1.5 m.
The test was conducted in the same manner as in Example 1 with m as the result, and the results are shown in Table 4.

[0021]

[Table 2]

Comparative Example 1. The granular abrasives shown in Table 3 below have a hardness of JISA95 and a rubber particle size of 0.7 to 1.0 m.
m, the test was conducted in the same manner as in Example 1, and the results are shown in Table 4.
It was shown to.

[0023]

[Table 3]

Comparative Example 2. Granular abrasives with hardness JIS A
A synthetic resin (Panlite: Teijin) having a particle size of 98 or more and a particle size of 0.7 to 1.0 mm was used, and the same test as in Example 1 was conducted. The results are shown in Table 4.

Comparative Example 3. A test was conducted in the same manner as in Example 1 using a sponge rubber in which the granular abrasive material of FIG. 3 was not adhered to the surface.

[0026]

[Table 4]

From Table 4, in the sponge rubber of Comparative Example 3 having no abrasive, Examples 1 and 2, no traces of scraping off on the iron protective coating were observed, but in Comparative Example 1, the scraping traces were in the water flow direction. Similarly, in Comparative Example 2, many shaving marks were observed, and the copper alloy substrate was exposed on some heat transfer tubes.

[0028]

[Effect] For the heat transfer tube of the tube heat exchanger made of copper alloy material, the cleaning ball of the present invention scrapes slime without causing damage to the heat exchanger such as scraping off the iron protective coating on the inner wall of the tube. By carrying out the cleaning which can be dropped and is highly efficient, there is an effect that the heat exchange efficiency can be improved and the life of the device can be extended.

[Brief description of drawings]

FIG. 1 is a sectional view of a cleaning ball of the present invention.

FIG. 2 is an enlarged view of a surface portion of the present invention.

FIG. 3 is a sectional view of a sponge rubber ball not coated with a granular abrasive.

FIG. 4 shows a heat transfer tube wear device.

[Explanation of Codes] 1 ... Sponge rubber ball 2 ... Rubber particles 3 ... Adhesive 4 ... Heat transfer tube 5 ... Circulation pump 6 ... Ball collector

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takuya Sasaki 1-284, Funacoshi-cho, Yokosuka City, Kanagawa 5 Hitachi Mechanical Engineering Co., Ltd. (72) Inventor Hideki Ima, 1-284, Funakoshi-cho, Yokosuka City, Kanagawa Prefecture 5 In Hitachi Machinery Engineering Co., Ltd. (72) Inventor Susumu Fukudome 5 in Hitachi Machinery Engineering Co., Ltd. 1-284, Funakoshi-cho, Yokosuka City, Kanagawa Prefecture

Claims (1)

[Claims] 1. An open-celled sponge rubber sphere having a softness so that it can pass through a heat transfer tube of a tubular heat exchanger while being in contact with the inner surface of the tube by a water flow, and a granular material adhered to the surface of the sponge rubber sphere. A cleaning ball comprising an abrasive, wherein the granular abrasive has a hardness of JISA 50 to 90 and a particle size that makes the surface of a sphere to which it is adhered uneven. ..