JP2886449B2 - Heat exchanger tube cleaning method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat exchanger tube cleaning method for cleaning an inner surface of a tube of a heat exchanger used for, for example, a regenerator of an absorption refrigerator.

[0002]

2. Description of the Related Art For example, in a heat exchanger using industrial water or natural water as a tube-side fluid, such as a regenerator of an absorption refrigerator, it is known that carbonate, silicate, etc. adhere to the inner surface of the tube. ing.

[0003] Since the heat exchange rate of the heat exchanger is reduced when such a carbonate or the like is attached, the inner surface of the tube is cleaned, for example, every one to two years. Conventionally, in cleaning such an inner surface of the tube, for example, there is a brush cleaning method in which a brush or the like is inserted into the tube to clean the tube, and this method can remove soft slime. Was difficult. Particularly in the case of copper or copper alloy tubes, brushing may damage the inner surface, and it has been difficult to adopt a brush cleaning method.

[0004] For this reason, for removing carbonates and the like, for example, a chemical solution is injected from a pipe connected to an inlet nozzle on the tube side and collected from a pipe connected to an outlet nozzle to circulate the chemical solution, and the chemical solution is used to remove carbonic acid on the inner surface of the tube. After dissolving the salt and the like, a chemical solution is discharged, and furthermore, water is circulated in the same manner to wash the inner surface of the tube.

[0005]

However, as described above, in the immersion circulation chemical cleaning method by circulating a chemical solution, a large amount of cleaning liquid is used, so that a large amount of cleaning waste liquid is required.
The neutralization and the like were not easy.

In addition, piping for temporary circulation and restoration after washing have been large.

[0007]

According to a first aspect of the present invention, there is provided a heat exchanger tube cleaning method using industrial water or natural water as a tube side fluid.
In cleaning the inner surface of the tube of the heat exchanger , at least one end of the tube was exposed, and the other end of the tube was opened to allow the washing liquid to flow out, and the tube was exposed. A jetting step of jetting a cleaning liquid from the exposed end of the tube to the tube and attaching the cleaning liquid to the inner surface of the tube; and, following the jetting step, a leaving step of leaving the tube sprayed with the cleaning liquid. After performing the cleaning process,
The inside of the tube is washed with water.

According to a second aspect of the present invention, in the method of cleaning a heat exchanger tube according to the first aspect, the inside of the tube is washed with water after performing the washing step a plurality of times. .

A third aspect of the present invention provides the heat exchanger tube cleaning method according to the first or second aspect, wherein the cleaning liquid is neutral or alkaline.
It is characterized in that an aqueous solution of the agent is used.

A method for cleaning a heat exchanger tube according to claim 4.
Is a method of cleaning a heat exchanger tube according to claim 1 or 2 , wherein an aqueous solution of an acidic cleaning agent is used as the cleaning liquid. A method of cleaning a heat exchanger tube according to a fifth aspect is characterized in that the cleaning method according to the fourth aspect is performed after the cleaning method according to the third aspect is performed.

[0011]

In the heat exchanger tube cleaning method according to the first aspect, at least one end of the tube is exposed before cleaning. In this operation, for example, in the case of a shell and tube type heat exchanger, one channel is removed to expose the tube sheet on this side. In the case of a type having a channel cover, only the channel cover may be removed.

After the end of the tube is exposed, as a spraying step, the washing liquid, which has been adjusted to an appropriate concentration in advance and stored in a tank, is pressurized by , for example, a pump to spray the nozzle.
At the above-mentioned exposed end into the tube
Adhere to the inner surface of the valve. At this time, wash the other end of the tube.
Keep open to allow outflow of clean solution. Once the cleaning solution
The injection is stopped, and as a leaving step, the washing liquid is left attached to the inner surface of the tube. This leaving step is to secure a time for waiting for the progress of the reaction between the cleaning solution and the carbonate, for example, and the time varies depending on the type and amount of the deposits, but is about 10 to 30 minutes. It is enough. After the cleaning step including the spraying step and the leaving step is performed as described above, the inside of the tube is cleaned by washing the inside of the tube with water to wash away the substance remaining in the tube after being removed from the tube.

As the cleaning liquid, any one used in the conventional immersion circulation chemical cleaning method by circulating a chemical solution can be used. For example, as a neutral cleaning liquid, a surfactant, hydrogen peroxide or the like is used as a main component. Examples of the alkaline cleaning liquid include those mainly containing sodium hydroxide, potassium hydroxide, sodium carbonate, sodium phosphate, sodium percarbonate and the like. Examples of the acidic cleaning liquid include those mainly containing hydrochloric acid, phosphoric acid, hydrofluoric acid, sulfuric acid, acetic acid, malic acid, and hydroxyacetic acid.

When the tubes are washed mainly for the purpose of removing soft slime, it is preferable to use a neutral or alkaline washing solution, and to remove scales such as carbonates, it is preferable to use an acidic washing solution. Further, the concentration of the cleaning liquid is not uniform depending on the kind, but generally when the concentration is higher than in the case of using the conventional immersion circulation chemical cleaning method, the cleaning effect is enhanced.

The jetting of the washing liquid varies depending on the length of the tube, the sending pressure of the washing liquid, the sending amount per time, and the like. In the case of a 6 m tube used in many regenerators, the discharge pressure of the pump is 10 kg / cm ² and the discharge pressure is 10 kg / cm ² . Approximately 3 at 5 l / min
A time of about 5 seconds to about 5 seconds is preferable from the viewpoints of the cleaning efficiency and the efficiency of the injection operation, but is not limited to this range.

Just by attaching the cleaning solution to the inner surface of the tube
Since the inside of the tube is not filled with the washing solution, the tube can be efficiently washed with a small amount of the washing solution. For this reason,
The amount of washing waste liquid becomes small, and the neutralization treatment and the like become easy.
In addition, since the cleaning solution is injected into the tube,
To blow off soft slime etc. attached to the inner surface
Can be removed. Removal of slime and carbonates and cleaning agents
Since the contact efficiency with the liquid is improved, the cleaning effect is improved.
In the case of a shell and tube type heat exchanger, for example, in order to inject the cleaning liquid into the tube, it is only necessary to remove one channel and expose the tube sheet. In addition, the cleaning liquid injected into the tube can be collected from a drain valve provided in the other channel. Therefore, it is necessary to remove and restore one channel.However, compared with the installation and removal of the temporary circulation circuit and the restoration work of pipes connected to the heat exchanger in the conventional immersion circulation chemical cleaning method, the amount of work is extremely small. No problem.

In the heat exchanger tube cleaning method according to the second aspect, the above-described cleaning step according to the first aspect is performed a plurality of times. That is, the injection step and the leaving step are performed alternately. Each step may be performed in the same manner as described above. The number of repetitions of the washing step depends on the type of scale or the like attached to the tube and the state of attachment, and is not determined uniformly. For example, an appropriate number of washing steps may be performed while visually checking the cleanliness of the inner surface of the tube.

If the washing liquid is sequentially sprayed on a large number of tubes provided in one heat exchanger, the above-mentioned standing time is required until the second and subsequent sprays are performed on the same tube. Therefore, it is not necessary to work to secure a special leaving time. Since the washing step is performed a plurality of times, it is effective for removing scales, such as silicate, which are difficult to remove.

[0019]

In the heat exchanger tube cleaning method according to the third aspect, since an aqueous solution of an alkaline cleaning agent is used as the cleaning liquid, the removal of soft slime is particularly improved. Claim 4
In the heat exchanger tube cleaning method described above, an aqueous solution of an acidic cleaning agent is used as the cleaning liquid, so that carbonates, silicates, and the like can be efficiently removed.

The heat exchanger tube cleaning method according to claim 5, wherein, after carrying out the cleaning method according to claim 3, claim 4
Since the described washing method is performed, removal of soft slime and removal of carbonate, silicate, and the like can be efficiently performed.
In addition, since the removal of the carbonate and the like is performed after the removal of the soft slime, the effect of removing the carbonate and the like becomes extremely good.

[0022]

Next, an embodiment of the present invention will be described. As shown in FIG. 1, the heat exchanger 10 includes a pair of tube sheets 1.
A shell 18 is provided which is connected between the shells 2 and 14 by a cylindrical shell barrel 16. A plurality of tubes 20 are inserted into the shell 18, and both ends of each tube 20 are fitted into tube holes provided in the tube sheets 12 and 14, and are fixed by expansion. A channel 22 is attached to the tube sheet 14 with bolts (not shown). When the heat exchanger 10 is operated, the channel 22 is also provided in the other tube sheet 12.
Although the same channel as that of FIG. 1 is mounted, the channel on the tube sheet 12 side is removed in the illustrated state. The channel 22 is provided with a nozzle 24 serving as a tube-side fluid passage.
Is connected. Further, a drain valve 28 capable of discharging the fluid in the channel 22 is mounted below the channel 22.

Now, the tube 2 of such a heat exchanger 10 will be described.
Heat exchanger tube cleaning device (hereinafter also simply referred to as a cleaning device) 30 employed in the present embodiment for cleaning the inner surface of the tube 30
The structure of the cleaning device 30 will be described. The cleaning device 30 is connected to the drain valve 28 via the connection hose 32. The other end of the connection hose 32 is connected to a filter 34.
The outlet side of the filter 34 is connected to the suction side 36 a of the suction pump 36, and the delivery side 3
6b is connected to the cleaning liquid tank 38.

The cleaning liquid tank 38 stores a cleaning liquid adjusted to a suitable concentration in advance. Into the cleaning liquid tank 38, a suction pipe 42 having a strainer 40 attached to the tip is inserted. The suction pipe 42 is connected to a suction side 44a of a pressure pump 44. The delivery side 44b of the pressurizing pump 44 is connected to an injection gun 48 via a flexible hose 46. Although not shown, two bypass lines are provided between the delivery side 44b and the suction side 44a of the pressurizing pump 44, and a safety valve and a pressure adjusting valve are interposed respectively. . Therefore, when the pressurizing pump 44 is operated, the pressure on the delivery side 44b is adjusted to the set pressure of the pressure adjusting valve. Also, for some reason, the delivery side 4
When the pressure at 4b becomes equal to or higher than the set pressure of the safety valve, the safety valve is opened and the pressure on the delivery side 44b can be reduced.
In addition, since the cleaning liquid discharged from the pressure regulating valve and the safety valve is returned to the cleaning liquid tank 38, there is no possibility that the cleaning liquid flows out.

The injection gun 48 is provided with a plurality of injection nozzles 52 fixed to the header 50. The communication between the flexible hose 46 and the injection nozzle 52 can be cut off by the injection switch 54. Therefore, when the fluid is supplied from the pressurizing pump 44, the fluid can be ejected from the ejection nozzle 52 and stopped according to the operation of the ejection switch 54.

Next, the operation of cleaning the inner surface of the tube 20 using the cleaning device 30 will be described. First, as shown in FIG. 1, the channel on the tube sheet 12 side of the heat exchanger 10 is removed, and the connection hose 32 is connected to the drain valve 28 of the channel 22 on the tube sheet 14 side. Prior to or in parallel with this work,
The cleaning liquid tank 38 is supplied with a cleaning liquid adjusted to an appropriate concentration in advance. Subsequently, the pressurizing pump 44 is operated, and the suction pump 36 is also operated. Then, FIG.
The injection nozzle 52 of the injection gun 48 is inserted into the tube 20 as illustrated in FIG. In this state, the injection switch 54
Is operated to make the injection nozzle 52 communicate with the flexible hose 46 side, and the cleaning liquid discharged from the pressure pump 44 is injected from the injection nozzle 52 into the tube 20.

After the injection of the cleaning liquid from the injection nozzle 52 is continued for a set time, the injection switch 54 is operated to cut off the communication between the injection nozzle 52 and the flexible hose 46, thereby temporarily stopping the injection of the cleaning liquid. This cleaning liquid injection time is
Although it is set according to the state of adhesion of salts and the like on the inner surface of the tube 20, about 3 to 5 seconds is usually sufficient.

The sprayed washing liquid comes into contact with the inner surface of the tube 20 so as to collide with the inner surface of the tube 20 to blow off the slime attached to the inner surface of the tube 20 and to remove carbonates such as calcium carbonate and the like attached to the inner surface of the tube 20. Dissolve silicates. The action of dissolving the carbonate and the like by the cleaning liquid is continued even after the injection of the cleaning liquid is stopped. For this reason, the cleaning efficiency is improved by securing a standing time after the injection of the cleaning liquid. This standing time of 10 to 30 minutes is sufficient.

Next, when the cleaning liquid is jetted again, the salts and the like dissolved by the previously jetted cleaning liquid are washed away by the jetted cleaning liquid, and together with the cleaning liquid, the channel 22 is washed.
Spills into. Subsequently, the injection is stopped, and the reaction between the cleaning liquid and the carbonate is waited in the same manner as described above. Further, while observing the degree of cleanliness of the tube 20, the spraying, stopping, and leaving of the cleaning liquid may be repeated.

After the washing liquid has been sprayed, stopped, and left for an appropriate number of times as described above, water is injected into the tube 20 to wash the inner surface with water to clean the inner surface of the tube 20. After that, restoration work such as installation of the channel is performed. The cleaning liquid sprayed into the tube 20 dissolves deposits such as carbonates on the inner surface of the tube 20 and separates the deposits from the inner surface of the tube 20 by the injection pressure, so that deposits such as carbonates on the inner surface of the tube 20 are efficiently removed. The washing of the inner surface of the tube 20 is short. Moreover, since a plurality of injection nozzles 52 are provided, a plurality of tubes 20 can be washed at the same time, and the washing efficiency is further improved.

The cleaning liquid flowing into the channel 22 is sucked by the suction pump 36 and collected in the cleaning liquid tank 38. At this time, since the solid matter contained in the cleaning liquid is filtered by the filter 34, such solid matter does not damage the suction pump 36. Cleaning liquid tank 38
The cleaning liquid collected in the step (a) is again sucked into the pressure pump 44 and discharged to the injection nozzle 52 side, so that the cleaning liquid is circulated. At this time, since the strainer 40 filters foreign substances in the cleaning liquid tank 38, such foreign substances do not damage the pressurizing pump 44 as in the case of the suction pump 36.

The amount of the cleaning liquid to be sprayed at one time may be such that the cleaning liquid sufficiently adheres to the inner surface of the tube 20. Since the spraying is performed intermittently, the amount of the cleaning liquid is extremely small. In addition, since the cleaning liquid that has passed through the tube 20 is collected and reused, the total amount of the cleaning liquid required for cleaning the inner surface of the tube 20 may be extremely small.

When the injection is temporarily stopped, the injection nozzle 52 is inserted into another tube 20, and the cleaning liquid is injected in the same manner as described above to wash the inner surface of the tube 20. Efficiency will be improved. The above operation is repeated one after another, and all the tubes 20 are washed and the washing operation is completed. In addition, as shown in FIG.
The injection nozzles 52 of the present embodiment cannot be inserted into the tubes 20 in the first row L1 or the like in which the number of the tubes 20 is less than six, but for the tubes 20 in such a row, the number of the injection nozzles 52 is, for example, one. An injection gun 48 having a small number of injection nozzles 52 such as two or two injection nozzles may be used. Further, the same applies to the tube 20 at the half end, such as the tube 20 at the right end of the second row L2.
Therefore, the flexible hose 46 is divided into, for example, two branches, and the injection gun 48 having a large number of the injection nozzles 52 is connected to one line, and the injection gun 48 having a small number of the injection nozzles 52 is connected to the other line. It is efficient to use the injection gun 48 properly.

As described above, according to the cleaning of this embodiment,
Deposits such as carbonates on the inner surface of the tube are efficiently removed. Moreover, since a plurality of injection nozzles 52 are provided,
A plurality of tubes 20 can be washed at the same time, and the washing efficiency is further improved. In addition, since the cleaning liquid that has passed through the tube 20 is collected and reused, the total amount of the cleaning liquid required for cleaning may be extremely small. (Examples 2 to 5) Next, Tables 1 and 2 show examples in which tubes of a heat exchanger used as a regenerator of an absorption refrigerator were washed by the washing method of the present invention. In the attached matter, calcium and magnesium are shown in terms of calcium carbonate.

[0035]

[Table 1]

[0036]

[Table 2]

As is clear from Tables 1 and 2, the cleaning method of the present invention can efficiently remove various kinds of deposits. (Comparison with the prior art) Table 3 below shows relative evaluations in terms of efficiency and cost between the conventional cleaning method and the cleaning method of the present invention.

[0038]

[Table 3]

As shown in Table 2, although the method of the present invention is slightly inferior to the conventional immersion circulation chemical cleaning method in removing silicate, it is excellent in other items. Further, the brush cleaning method is inferior in removing salts as compared with the other two methods. Although the embodiments have been described above, the present invention is not limited to such embodiments, and can be variously implemented without departing from the gist of the present invention.

For example, in the embodiment, an injection gun having six injection nozzles is illustrated, but the number of injection nozzles is not limited to six, but may be one to five or seven or more. The outer diameter of the injection nozzle is not particularly limited as long as it can be inserted into the tube.

Further, in the above example, the cleaning liquid is recovered from the drain of the channel, but the recovery source is not limited to the drain. Further, the collection is not essential, and the collection and reuse do not have to be performed. However, the collection is preferably performed because many cleaning liquids used for washing the tubes contain harmful substances such as components corresponding to powerful drugs.

In the above example, the washing of the straight tube type heat exchanger tube has been described. However, it is needless to say that the present invention can be applied to tubes of various shapes such as a U-shaped tube and a coiled coiled tube.

[0043]

As described above, the heat of claim 1
According to the exchanger tube cleaning method, heat exchange with a small amount of
The inner surface of the heat exchanger tube can be efficiently cleaned,
Since the amount of waste liquid is small, neutralization and the like are also easy. Only
Also, since the cleaning solution is injected into the tube,
Blow off soft slime etc. attached to
Can be removed.
Since the contact efficiency is improved, the cleaning effect is improved.

Also, the number of disassembly and restoration of the heat exchanger accompanying the washing operation is extremely small as compared with the installation and removal of the temporary circulation circuit and the restoration work of the piping connected to the heat exchanger in the conventional immersion circulation chemical washing method. Only the amount of work is needed. In the heat exchanger tube cleaning method according to the second aspect, since the cleaning step is performed a plurality of times, it is effective for removing scales that are difficult to remove such as silicate.

[0045]

In the heat exchanger tube cleaning method according to the third aspect, since an aqueous solution of an alkaline cleaning agent is used as the cleaning liquid, the removal of soft slime is particularly excellent. Claim 4
In the heat exchanger tube cleaning method described above, an aqueous solution of an acidic cleaning agent is used as the cleaning liquid, so that carbonates, silicates, and the like can be efficiently removed.

The heat exchanger tube cleaning method according to claim 5, wherein, after carrying out the cleaning method according to claim 3, claim 4
Since the described washing method is performed, removal of soft slime and removal of carbonate, silicate, and the like can be efficiently performed.
In addition, since the removal of the carbonate and the like is performed after the removal of the soft slime, the effect of removing the carbonate and the like becomes extremely good.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a configuration of a heat exchanger tube cleaning device used in an example.

FIG. 2 is an explanatory view showing a state in which an injection nozzle is inserted into a tube during a cleaning operation by the heat exchanger tube cleaning apparatus according to the embodiment; FIG. 2 (a) is an explanatory view of a tube opening side; FIG. FIG. 3 is a partial cross-sectional view along the axial direction of the tube.

[Description of References] 10 ... Heat exchanger, 12, 14 ... Tube sheet, 18 ... Shell, 20 ... Tube, 28 ...
・ Drain valve, 30 ・ ・ ・ Heat exchanger tube washing device, 36 ・ ・ ・ Suction pump (recovery pump), 38 ・ ・ ・
Cleaning liquid tank, 44 ... Pressure pump, 52 ... Injection nozzle.

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁶ , DB name) F28G 9/00

Claims (5)

(57) [Claims] Claims: 1. An industrial water or a natural water as a tube side fluid.
In cleaning the inner surface of the tube of the heat exchanger using at least one end of the tube is exposed, and the other end of the tube is opened to allow the washing liquid to flow out, and the tube is exposed. an injection step of adhering to the inner surface of been from the end by ejecting a cleaning liquid into the tube the tube, the above washing solution subsequent to the injection step
A method for cleaning a heat exchanger tube, comprising performing a cleaning step including a leaving step of leaving the jetted tube to stand, and then washing the inside of the tube with water. 2. The method according to claim 1, wherein the inside of the tube is washed with water after performing the washing step a plurality of times. 3. The heat exchanger tube cleaning method according to claim 1, wherein an aqueous solution of a neutral or alkaline cleaning agent is used as the cleaning liquid. 4. The method for cleaning a heat exchanger tube according to claim 1, wherein an aqueous solution of an acidic cleaning agent is used as the cleaning liquid. 5. A method for cleaning a heat exchanger tube, wherein the cleaning method according to claim 4 is performed after the cleaning method according to claim 3 is performed.