JPH05180594A - Heat transfer tube inner surface cleaning device for heat exchanger - Google Patents

Abstract

PURPOSE:To obtain a heat transfer tube inner surface cleaning device for a heat exchanger in which scale, slime adhered to the inner surface of the tube are removed without decreasing an efficiency of a plant even if chemicals are not poured in a coolant system and adherence thereof is prevented. CONSTITUTION:Cleaning medium 10 of a low temperature is poured by a cleaning medium supply unit 8, a cleaning medium supply controller 11 and a tube inner dirt sensor 12.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a system for cleaning the inner surface of a heat transfer tube in a heat exchanger, and more particularly to slime and scale attached to the inner surface of the heat transfer tube of a multi-tube heat exchanger such as a condenser in a power plant. The present invention relates to a heat transfer tube inner surface cleaning device that cleans and removes and prevents adhesion.

[0002]

2. Description of the Related Art Conventionally, in a heat transfer tube of a heat exchanger used as a cooler, scales such as scales and rust are generated and bacterium, algae, and fungi are proliferated due to increase of water temperature, and dust and the like are accumulated in these. When it is mixed, slime that has turned into a soft mud is produced. If these adhere to the inner wall surface of the pipe, the heat exchange capacity will deteriorate and heat transfer pipe corrosion holes will be generated.
In particular, in the case of a condenser or the like, the efficiency of the steam turbine decreases with the decrease in heat transfer performance, and the output of the generator decreases, resulting in a huge loss. As measures against these, at present, scales and slimes are removed by using a cleaning agent made of chemicals, but since the waste liquid after cleaning becomes a pollution problem of water pollution, neutralization treatment etc. was necessary. In particular, in the case of a heat exchanger using seawater, since a large amount of cooling water is used, a method without using chemicals is being taken from the fear that the marine ecosystem will be changed even if there is no outflow of chemicals. As a cleaning method that does not use chemicals, sponge balls are put into and suspended in cooling water to clean the sponge balls while flowing through the heat transfer tube, but the sponge ball wear measurement and operation management for replenishment are troublesome. There was a drawback. In addition, as seen in Japanese Patent Laid-Open No. 59-10381,
The method of mixing and circulating resin particles in cooling water has sufficient cleaning effect for initial slime formation and scale adhesion.
However, the slime or scale that has grown to some extent weakens the collision of the particles with the wall surface, and the cleaning effect may suddenly decrease. Further, since the resin particles will flow out into the ocean, it is necessary to install a particle recovery facility due to environmental problems, which causes problems in terms of cost and management.

Further, as disclosed in Japanese Patent Laid-Open No. 61-25498, a method has been proposed in which a gas is released into a liquid in the form of bubbles at the inlet end of a heat transfer tube and ultrasonic waves are transmitted to this gas-liquid mixed flow. However, it requires a large amount of money to install the ultrasonic wave transmitter. At this time, if it is attempted to clean only by the gas-liquid two-phase flow, the cleaning effect will be limited by the bubbly flow, and sufficient performance can be obtained in a heavily polluted place, generation of slime, and active summer. There were drawbacks such as difficulty. Further, as disclosed in Japanese Patent Laid-Open No. 59-30000, there has been proposed a device for cleaning a heat transfer tube by using a three-phase flow of water, sand and air. Although it seems that the cleaning effect is very large, the cleaning is locally performed violently, which may partially damage the heat transfer tube. Moreover, since cleaning cannot be performed during operation, no consideration has been given to cleaning without lowering plant efficiency.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to clean a large number of heat transfer tubes in a reliable and effective manner and without impairing the operation of the heat exchanger, and yet to perform heat exchange. It is intended to improve the performance of the container and provide a cleaning system that does not affect the natural environment.

[0005]

In order to achieve the above object, the present invention is a multi-tube heat exchanger in which a liquid flows in a heat transfer tube, and the temperature of the liquid flowing in the heat transfer tube is lower than that of the liquid. The cleaning medium was allowed to flow down periodically to remove deposits in the pipe and prevent dust and bacteria from depositing. Further, the cleaning medium supply device is arranged at the inlet of the heat transfer pipe on the cooling water inlet side of the heat exchanger, and the cleaning medium supply device is moved so that the input low temperature cleaning medium is evenly distributed over many heat transfer pipes. I did it.

Further, in order to perform the cleaning effectively, the present invention is provided with a control device, and in order to perform the optimum cleaning, the cleaning time is determined according to the dirty state in the pipe, and the cleaning time, the cleaning interval, etc. are determined. It was controlled and automatic operation was enabled.

[0007]

Since the method of the present invention does not use chemicals, it does not cause pollution problems such as water pollution of the ocean. Moreover, in order to remove the deposits in the pipe and prevent the attachment of sludge and bacteria,
By arranging a movable cleaning medium supply device at the inlet of the heat transfer tube on the cooling water inlet side of the heat exchanger, the cleaning medium at a temperature lower than that of the cooling water flows evenly into a large number of heat transfer tubes. Since uniform and reliable cleaning can be performed even in a place where the flow is slow, damage to the heat transfer tube due to excessive local cleaning can be prevented, and the cleaning effect can be greatly improved. Further, since the particles of low temperature are used, the condensation of steam is promoted as compared with the case of using only cooling water, so that the condensing efficiency is also improved. Further, according to the present invention, it is possible to determine the charging time of the cleaning medium and control the charging time and the charging interval according to the contamination state in the tube, so that it is possible to always maintain the optimum inner surface of the heat transfer tube. That is, it is possible to effectively remove or prevent the adhered matter in the heat transfer tube. In addition to protecting the natural environment, a cleaning medium that can be drained to the ocean after cleaning is used.Therefore, there is no need to collect cleaning media or install equipment such as a circulation system. is there. Also, by detecting the timing of introducing the cleaning medium based on how dirty the heat transfer tubes are, it is possible to perform automatic operation without the hassle of management, and to perform cleaning during operation without shutting down the plant. Therefore, it is possible to reduce the cost of the overall cleaning device and improve the plant efficiency.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIG. FIG. 1 is a system diagram in which the present invention is applied to a condenser of a power plant. A large number of heat transfer tubes 3 are supported by a tube plate 2 inside the condenser main body 1, and are guided to an inlet side water chamber 5 of cooling water 4 which is connected to the main body 1 at the inlet side of the heat transfer tubes 3. The cooled cooling water 4 passes through the inside of the heat transfer tube 3 and reaches the outlet side water chamber 6 connected to the main body 1 at the outlet side of the heat transfer tube 3.

On the other hand, the steam 8 flowing in from the steam inlet 7 in the upper part of the condenser body 1 is heat-condensed with the cooling water 4 in the heat transfer tube 3 to be condensed, and becomes condensed water 9 in the lower part of the body. It is configured to be drained from the outlet 10. Further, in the main body 1, the cleaning medium supply device 11 provided in the inlet-side water chamber 5 is provided with the cleaning medium ejection port 12, and when the cleaning medium ejection port 12 is opened, the cleaning medium supply device 11 The cleaning medium 13 is introduced into the outlet side water chamber 6 through the inside of the heat transfer tube 3. Here, the cleaning medium 13
For this purpose, particles having a specific gravity larger than water are suitable, and the temperature of the particles is preferably a temperature at which marine organisms and the like attached to the heat transfer tubes are less likely to inhabit, and 5 ° C. or lower is preferable. Thus, low temperature particles 13
Is added to improve the endothermic effect of the heat transfer tube 3 and accelerate the condensation of steam, which is desirable for improving the performance of the condenser. Further, the particles 13 have a size that allows them to pass through the heat transfer tube 3, and particularly those having a diameter of 1 mm to 3 mm are preferable in terms of handling and cleaning effects due to the particles 13 colliding with the wall surface in the heat transfer tube 3. ..

Next, the cleaning medium supply controller 1 will be described with reference to FIG.
4 will be explained. The cleaning medium supply control device 14 controls the movement of the cleaning medium supply device 11 and the opening / closing of the cleaning medium ejection port 12. At the position I, the cleaning medium ejection port 12 near the center without the tube nest 15 is closed. Cleaning medium supply device 11
As is lowered, at the position II, only both ends with the tube nest 15 are opened, and at the position III, near both ends without the tube nest 15 are closed. In this way, since the opening / closing of the cleaning medium ejection port 12 is controlled according to the presence or absence of the tube nest 15 associated with the movement of the cleaning medium supply device 11, the cleaning medium 13 can be efficiently introduced without waste. Further, the cleaning medium supply control device 14
Since the cleaning medium 13 is evenly distributed to each heat transfer tube by providing the above, the cleaning is locally performed violently and the heat transfer tube is not partially damaged. Furthermore,
By providing the in-pipe dirt detection device 16 that detects the degree of dirt on the inner surface of the heat transfer tube 3 and determines when to insert the cleaning medium 13, the cleaning time and the interval at which the cleaning medium 13 is charged can be controlled. This is to automate the process from the start to the end of cleaning as the heat transfer performance deteriorates due to the effect of slime adhering to the inner surface of the heat transfer tube 3, and the fouling inside the heat transfer tube 3 is detected by the fouling detection device 16 inside the tube. By doing so, the cleaning medium supply device 11 and the cleaning medium ejection port 12 are activated in cooperation with the cleaning medium supply control device 14.
As described above, the condenser of the present invention includes the cleaning medium supply device 11
The low temperature particles 13 are charged by the cleaning medium supply controller 14 and the inside of the heat transfer tube 3 is cleaned using the solid-liquid two-phase flow of the particles 13 and the cooling water 4 as shown in FIG. Since the turbulence of the liquid is strong, the energy with which the particles 13 collide with the wall surface is increased, creating an environment in which in-tube deposits 17 such as slime are less likely to be generated. Therefore, it is possible to obtain a system having a large cleaning effect. Further, by making the cleaning medium supply device 11 movable, the particles 13 are uniformly mixed into the heat transfer tube 3 and reliable cleaning can be performed, so damage to the heat transfer tube 3 due to local overcleaning can be prevented. Since it is possible to perform safer cleaning, it is possible to always maintain the optimum inner surface of the heat transfer tube. Further, by detecting the degree of fouling in the heat transfer tube 3 by the fouling detection device 16 in the tube, it is possible to determine the loading time of the cleaning medium 13 and control the loading time, loading interval, etc., so that automatic operation becomes possible.

Next, another embodiment of the present invention will be described with reference to FIG. Cleaning particles 13 at a low temperature, which has an effect of generating a gas 18 by coming into contact with the cooling water 4 flowing in the heat transfer tube 3.
When is charged, the flow in the pipe becomes a solid-gas three-phase flow of the particles 13, the gas 18, and the cooling water 4. Therefore, the flow in the pipe is disturbed and the density of the particles 13 and the gas 18 colliding with the inner wall surface of the pipe is increased, so that the adhered substance 17 in the pipe such as slime can be removed to prevent the adherence. Here, cleaning particles 1
3 is desirable in that dry ice has a low temperature and that gas 18 is generated. Furthermore, since dry ice vaporizes with the passage of time, it can be discharged to the ocean together with drainage after cleaning, so there is no need for a facility for recovery, resulting in a significant cost reduction. Further, the generated gas 18 is discharged from the existing air extraction port 19 to the water chamber air vent pump 2
Since it is extracted by 0, there is no operational problem.

[0012]

EFFECTS OF THE INVENTION According to the present invention, since the heat transfer tubes are cleaned by introducing particles having a temperature lower than that of the cooling water, the temperature of the cooling water is lower than that during normal operation and the condensing efficiency is improved. It can be done. Further, since the movable type particle supply device is installed, it is possible to uniformly and periodically add particles to a large number of heat transfer tubes. Further, since the particle ejection port is opened and closed depending on the presence or absence of the tube nest of the heat transfer tube by providing the control device, the heat transfer tube is not damaged by local overwashing. Further, by detecting the dirt in the heat transfer tube, it is possible to judge the cleaning time and control the particle charging time and particle charging interval, which enables automatic operation. In addition, by introducing low-temperature particles that generate gas when contacting cooling water with a size that can pass through the heat transfer tube and that melts over time, the tube flow becomes a solid-gas liquid three-phase flow. To do. As a result, the density at which the particles collide with the inner surface of the heat transfer tube is increased, and the cleaning effect is improved, which enables optimum cleaning. Further, since the particles melt with the passage of time, there is no effect on the natural environment and there is no need to recover the particles after cleaning, so that an ideal cleaning system can be established.

[Brief description of drawings]

FIG. 1 is a system diagram showing an embodiment of the present invention.

FIG. 2 is an explanatory diagram of a particle supply control device.

FIG. 3 is an explanatory diagram of a flow situation in the heat transfer tube.

FIG. 4 is an explanatory diagram of a flow state in a heat transfer tube when particles that generate gas are used.

[Explanation of symbols]

1 ... Condenser body, 2 ... Tube plate, 3 ... Heat transfer tube, 5 ... Inlet side water chamber, 6 ... Outlet side water chamber, 7 ... Steam inlet, 10 ... Condensate outlet,
11 ... Cleaning medium supply device, 12 ... Cleaning medium ejection port, 14
... cleaning medium supply control device, 16 ... contamination detection device for pipe, 1
9 ... Air extraction port, 20 ... Water chamber air vent pump.

Front Page Continuation (72) Inventor Katsuki Otaki 3-1-1, Saiwaicho, Hitachi-shi, Ibaraki Hitachi Ltd. Hitachi factory

Claims (6)

[Claims] 1. In a multi-tube heat exchanger in which a liquid flows in a heat transfer tube, a cleaning medium supply device is provided at an inlet end of the heat transfer tube, and a cleaning medium having a temperature lower than that of the liquid flowing in the heat transfer tube is introduced. An inner surface cleaning device for heat transfer tubes in a heat exchanger, which is characterized in that: 2. The cleaning medium supply device according to claim 1, wherein the cleaning medium supply device is movable, the inlet for the cleaning medium is opened, and the cleaning medium supply device is moved to transfer the low-temperature cleaning medium into the heat transfer tube. A heat transfer tube inner surface cleaning device in a heat exchanger provided with a control device for uniformly and periodically flowing in. 3. The apparatus according to claim 1, wherein a device for detecting the degree of contamination in the heat transfer tube is provided to determine the cleaning time in the heat transfer tube, and accordingly, the cleaning medium supply device is activated, A heat transfer tube inner surface cleaning device for a heat exchanger that inputs a low-temperature cleaning medium. 4. The heat transfer pipe inner surface cleaning device according to claim 1, wherein the heat transfer pipe inner surface has a size capable of passing through the heat transfer pipe and is charged with the low temperature cleaning medium. 5. The flow in the heat transfer tube as claimed in claim 1, wherein low temperature cleaning particles having an effect of generating gas by contacting with a liquid flowing in the heat transfer tube are charged from the cleaning medium supply device. An inner surface cleaning device for heat transfer tubes in a heat exchanger with solid-liquid three-phase flow. 6. The method of cleaning a heat transfer tube inner surface in a heat exchanger according to claim 1, wherein after cleaning the inside of the heat transfer tube, low temperature particles having a function of melting by contact with a flowing liquid are charged.