JP4596665B2 - Tube cleaning method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a pipe cleaning method, and more particularly, to a piping system cleaning method such as a water supply system, an air conditioning cooling water system, and a heat exchanger water system.
[0002]
[Prior art]
Rust, scale, scale, foreign matter, and the like adhere to the inner surface of a pipe used in a piping system or the like, and various methods have been used in the past for cleaning the pipe to remove it.
In general, the inside of a pipe is filled with a cleaning solution for a certain period of time and then discharged to wash the inside of the pipe, the method of physically removing foreign substances with high-pressure air, or the case where fluid always flows like a heat exchanger A method of flowing a cleaning solution in the opposite direction of the flow is employed.
As a measure for increasing the cleaning power, Japanese Patent Laid-Open No. 8-281233 causes two kinds of cleaning liquids having different temperatures to flow in the pipe to expand or contract the foreign matter adhering to the pipe, so that there is a gap between the wall surface of the pipe and the foreign substance. A cleaning method is disclosed in which foreign matter is peeled off from the wall surface. However, such a method utilizing the thermal expansion and contraction of foreign matter is ineffective when the coefficient of thermal expansion of the tube and the foreign matter is not significantly different, and is also effective when a flexible substance is in close contact. Absent.
Japanese Patent Laid-Open No. 10-15513 discloses a method of cleaning the inside of a pipe by filling a piping system with a cleaning liquid, pressurizing the cleaning liquid with a pressurizing means, and discharging the cleaning liquid after a predetermined time. According to the gazette, by pressurizing the inside of the pipe in this way, it is possible to enhance the cleaning effect of the cleaning liquid that dissolves the attached rust and deposits. However, this method aims to supply the cleaning liquid over the entire pipe (that is, the entire deposit), and the effect is considered not to be different from the cleaning effect by the cleaning liquid.
Furthermore, Japanese Patent Laid-Open No. 10-414690 discloses an in-pipe cleaning machine that removes foreign matter by spraying cleaning liquid and then spraying compressed air, but such a device is not suitable for complicatedly shaped narrow tubes. Obviously, no matter how high the cleaning effect is, if it is expensive, practical applications are limited.
[0003]
[Problems to be solved by the invention]
In reality, various foreign substances that are difficult to remove adhere to the inside of the tube. For example, in the case where the inside of the tube is designed to be high temperature, it is extremely difficult to remove the organic substance in the tube. Also, the tube itself is designed in various shapes, and it is difficult to clean a tube having a structure in which the cleaning liquid is difficult to reach or a structure in which the cleaning liquid is difficult to circulate. In particular, it has been difficult to remove those in which scale has been solidified by heat, such as a heat exchange tube constituting a heat exchanger. Further, there has been a demand for a method that increases the cleaning effect by using a cleaning device that has been conventionally used, for example, with a device that is as simple as possible. That is, the present invention aims to more effectively perform the cleaning of the pipe without using a special device, and in particular, to provide a cleaning method effective for removing the scale stuck in the pipe of the heat exchanger. And
[0004]
[Means for Solving the Problems]
As a result of examining in detail the foreign matter adhering to the inside of the pipe such as a heat exchanger, the present inventor removed the water and the cleaning liquid from the inside of the pipe to pressurize the inside of the pipe so that the attached matter is not wet, It has been found that a gap may be formed between the deposit and the inner wall of the pipe by repeating the operation of pressurization. Probably, it is thought that a minute bubble or space existing between the deposit and the inner wall of the tube expands and contracts by pressurization and non-pressurization to form a gap between the deposit and the inner wall of the tube. In particular, it has also been found that in the case of scale solidified in the tube of the heat exchanger, it is more effective if it is immersed in water or a cleaning liquid after pressurization. The inventor has reached the present invention through these discoveries.
That is, the present invention relates to a pipe cleaning method for removing deposits on a wall surface in a pipe (excluding an elastic pipe), a step of cleaning the inside of the pipe by flowing water or a cleaning liquid through the pipe for a predetermined time, and There is provided a tube cleaning method characterized by repeating a cleaning operation comprising a step of applying a high-pressure gas pressure using air or nitrogen at normal temperature after draining water or a cleaning liquid and then reducing the pressure to atmospheric pressure at least once. This cleaning method is particularly effective for cleaning the heat exchange tubes constituting the heat exchanger.
[0005]
DETAILED DESCRIPTION OF THE INVENTION
The cleaning method of the present invention comprises two stages: a first process in which water or cleaning liquid is allowed to flow through the pipe for a predetermined time to clean the inside of the pipe, and a second process in which a predetermined gas pressure is applied after draining the water or cleaning liquid from the pipe. . Any of these steps may be performed first, and in order to further improve the cleaning effect, another cleaning step or foreign matter discharging step may be added between these two steps as appropriate.
Hereinafter, the cleaning method of the present invention will be described using the piping shown in FIG. Note that the piping shown in FIG. 1 and its cleaning method are merely examples of application examples of the cleaning method of the present invention, and are not intended to limit the present invention. The method of the present invention can be applied to any conventional piping or piping using a valve.
[0006]
First, in the first step, one valve 3 in FIG. 1 is closed, and a cleaning liquid or water is filled into the pipe from the other valve 2. At this time, the cleaning liquid or the like is filled while adjusting the valve 2 so as to release air so that the adhering material is evenly immersed in the cleaning liquid or water without leaving any air in the pipe. Although it depends on the kind of the deposit, the deposit becomes flexible when immersed in the cleaning liquid or water, and the effect of the second step may become more remarkable. For this reason, it is more effective to heat the cleaning liquid or water appropriately. In addition, an appropriate time for filling the inside of the tube with a cleaning liquid or water and then allowing these liquids to flow through the tube depends on the type of deposits, and thus is appropriately determined.
Further, once the inside of the pipe is filled with these liquids in this way, the cleaning liquid or water is allowed to flow through the pipe to discharge the deposits that have peeled off at this stage or the previous stage. Alternatively, the inside of the tube may be flushed with water for a certain period of time, and then the inside of the tube may be washed away with water. Furthermore, not only mere water and cleaning liquid are allowed to flow, but also high-pressure water and cleaning liquid may be injected into the pipe.
Any kind of surfactant, acid, alkali, organic solvent, etc. may be used for the cleaning liquid, and the most effective one should be used depending on the type of deposits and tubes.
[0007]
Next, in the second step, the valve 3 is opened, and either the water or the cleaning liquid filled in the pipe is discharged. In this case, it is preferable to completely discharge the water or the cleaning liquid, but it may be discharged as far as practically possible. At this time, the compressed air may be introduced from the valve 2 to forcibly discharge the water or the cleaning liquid.
Subsequently, the valve 2 is closed, and the valve 3 is connected to a pump for supplying compressed air, a high-pressure nitrogen cylinder or the like, and the inside of the pipe is pressurized. In this case, the higher the gas pressure, the more effective. Therefore, it is preferable to increase the pressure to the pressure limit of the valves and pipes constituting the piping. Therefore, this gas pressure may be appropriately determined according to the piping system to be cleaned using the present invention. Further, the longer the time for pressurization, the more effective, but it is determined appropriately depending on the degree of adhesion of the deposit. While pressurizing the inside of the pipe in this way, the minute space existing between the deposit and the inner wall of the pipe shrinks due to pressurization, and when the pressure is returned to atmospheric pressure, the pressure between the deposit and the inner wall of the pipe is not increased. It is considered that a gap is formed larger than that and the deposits are separated from the inner wall of the pipe.
[0008]
In the cleaning method of the present invention, such a cleaning operation including the first step and the second step is repeated at least once. It is clear that the greater the number of repetitions, the more effective the cleaning, but the degree of cleaning depends on the type of deposits, the type of cleaning liquid used, the temperature of water and cleaning liquid, and other cleaning processes that are optionally added. Because it depends, it cannot be decided unconditionally, but there will be limitations due to cost effectiveness.
[0009]
【The invention's effect】
In the present invention, pipes can be more effectively cleaned by using compressed air that is usually in a factory without using a special device. Further, the cleaning method of the present invention was particularly effective for removing scales stuck in the pipe of the heat exchanger.
[Brief description of the drawings]
FIG. 1 is a diagram showing an example of piping to which a cleaning method of the present invention is applied.
[Explanation of symbols]
1 Pipe to be cleaned 2, 3 valves

Claims (2)

In a tube cleaning method for removing deposits on a wall surface in a tube (excluding an elastic pipe), a step of cleaning the tube by flowing water or a cleaning solution into the tube for a predetermined time, and removing the water or the cleaning solution from the tube A tube cleaning method characterized by repeating a cleaning operation comprising a step of applying a high gas pressure using air or nitrogen at normal temperature and then reducing the pressure to atmospheric pressure at least once.   The tube cleaning method according to claim 1, wherein the tube is a heat exchange tube constituting a heat exchanger.

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