JPH058360B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention relates to a method and apparatus for cleaning a heat exchanger.

2. Description of the Related Art Generally, a heat exchanger has a first passage and a second passage through which a first fluid and a second fluid that exchange heat with each other pass separately. In a multi-tubular heat exchanger, one of the first passage and the second passage is composed of a plurality of metal tubes arranged in the other passage, and an inlet and an outlet are provided before and after these tubes.

When a gas is used as the first fluid and water is used as the second fluid to absorb heat from the hot gas with water, the gas passes through a number of tubes that are placed underwater.
If this gas is emitted from an internal combustion engine,
Exhaust gas contains various components such as water vapor and sulfur in addition to carbon dioxide gas. When heat is exchanged between the exhaust gas and water, the exhaust gas is cooled by the water, so water vapor in the exhaust gas condenses, and the condensed water adheres to the inner wall of the pipe as water droplets. These water droplets react with sulfur in the exhaust gas to produce sulfuric acid, and the inner wall of the metal pipe is corroded by the sulfuric acid. This shortened the life of the heat exchanger. Conventionally, various measures have been taken to prevent corrosion of the inner walls of pipes.
First, measures have been proposed to ensure that no condensed water is generated, that is, to maintain the exhaust gas temperature at the outlet at a higher temperature. With this method, heat exchange efficiency was significantly reduced because sufficient heat could not be recovered from the exhaust gas. Secondly, methods have been proposed for forming the tubes from corrosion-resistant materials or for treating the inner walls of the tubes with this material. However, this method is also not practical because the manufactured tubes are expensive.Alternatively, there is a method of increasing the wall thickness of the tubes, but due to the increased weight, it is not appropriate to use heat exchangers in vehicles. do not have. Furthermore, there is a method in which cleaning staff clean the area at regular intervals.
This method is also very cumbersome as it requires cleaning every short period of time, and cleaning may not be possible depending on the mounting position on the heat exchanger.

Problems to be Solved by the Invention The present invention solves the above-mentioned drawbacks, and provides a method and apparatus for cleaning a heat exchanger that can be automatically cleaned while maintaining high heat exchange efficiency.
The cleaning device of the present invention can be manufactured relatively inexpensively and lightweight.

Summary of the Invention In the heat exchanger cleaning method according to the present invention, condensed water obtained within the heat exchanger is introduced into a container, and the concentration of a specific component contained in the condensed water is measured. It is detected whether this concentration is above a predetermined level, and when it is above the predetermined level, the cleaning liquid is supplied into the heat exchanger.

The heat exchanger cleaning device according to the present invention is a device that is directly used to carry out the above cleaning method, and this device includes a sensor that generates an electrical signal in response to a specific component contained in condensed water contained in a container. , a comparison circuit that generates a drive signal when the electric signal from the sensor is at a predetermined level or higher, and a cleaning liquid supply means that receives the drive signal from the comparison circuit and supplies cleaning liquid into the heat exchanger.

Embodiments Hereinafter, embodiments of the present invention will be described with reference to the drawings. As shown in FIG. 1, the heat exchanger 10 includes a first passage 11 through which a first fluid such as exhaust gas passes;
It has a second passage 12 through which a second fluid such as water passes. The first passage 11 has an inlet 13 and an inlet 1
an expansion chamber 14 connected to the expansion chamber 3 and having a size that gradually expands; a large number of metal tubes 15 connected to the expansion chamber 14; and a contraction chamber connected to the outlet of the metal tube 15 and having a substantially same shape as the expansion chamber 14. An outlet 17 communicating with the rear of the chamber 16 is provided. A pair of partition plates 18 and 19 are fixed to both ends of the metal tube 15, and a cooling chamber 20 is formed between them. The cooling chamber 20 is provided with an inlet 21 and an outlet 22 of the second passage.

In the cleaning device of the present invention, a pipe 24 communicating with a container 23 is attached below the contraction chamber 16. A pipe 26 communicating with a valve 25 is connected to the lower part of the container 23 . A pipe 27 connected to the valve 25 is connected to a known drain pipe. Inside the container 23, a sensor 28 is installed.
is fixed. This sensor may be a PH meter sensor such as a glass electrode that measures acid or alkali concentration, or a known sensor used in devices that measure the concentration of other corrosive substances.

This sensor 28 is electrically connected to a control circuit 30. The control circuit 30 is also electrically connected to a solenoid 31 forming the first electromagnetic valve 29 , a solenoid 33 forming the second electromagnetic valve 32 , and a motor 35 driving the pump 34 . Just as valve 25 is actuated by solenoid 31, valve 36 connected to pump 34 is actuated by solenoid 33. Valves 25 and 36 are normally closed and open only when solenoids 31 or 33, respectively, are energized. The pump 34 is
connected to a tank 38 in which a cleaning liquid 37 is stored;
It is also connected to a water fountain 40 through a valve 36. Solenoid 33, valve 36, pump 34 and motor 3
5 constitutes a cleaning liquid supply means 49. fountain 40
is fixed so as to protrude from the inlet 13 of the heat exchanger 10, and is set so as to be able to spray cleaning liquid toward the metal tube 15. In the illustrated example, the heat exchanger 10 is tilted and fixed by a certain angle θ.

FIG. 2 shows details of the control circuit 30. This control circuit 30 includes an amplifier 41 connected to the sensor 28, a differential amplifier 44 having a non-inverting input terminal 43 that receives the output of the amplifier 41 through an OR gate 42, and a transistor 45 that amplifies the output of the differential amplifier 44. and has. The differential amplifier 44 and the transistor 45 constitute a comparison circuit 39. OR
The other input terminal of the gate 42 is connected to a manual switch 46 and an inverting input terminal 47 of the differential amplifier 44.
is connected to a constant voltage power supply 48 that determines the reference level. The collector of the transistor 45 is connected to the power supply, and the emitter is connected to the limiting resistors 50, 51, 5.
2 to solenoids 31 and 33 and a motor 35, respectively.

The operation of the above cleaning device will be explained below. The high temperature exhaust gas passing through the first passage 11 of the heat exchanger 10 is cooled by water circulating in the cooling chamber 20 as it passes through the metal tube 15 . Inside the metal tube 15, the water vapor contained in the exhaust gas is cooled and becomes a large number of water droplets that adhere to the inner wall of the metal tube 15.
These water droplets react with inorganic substances such as sulfur or organic substances contained in the exhaust gas to form corrosive substances such as sulfuric acid or alkali. Since the heat exchanger 10 is fixed at a fixed angle, the water droplets attached to the inner wall of the metal tube 15 grow to a certain size, and then
It begins to flow towards the outlet 17 and falls downward within the contraction chamber 16. This condensed water passes through tube 24 and is collected in container 23.

A sensor 28 mounted within the vessel 28 generates a voltage corresponding to the concentration of corrosive material contained in the condensate it contacts. This voltage is amplified by an amplifier 41 and then passed through an OR gate 42 to a differential amplifier 4.
It is applied to the non-inverting input terminal 43 of No. 4. OR gate 42 transmits the analog signal from amplifier 41 to non-inverting input terminal 43. The differential amplifier 44 is
The voltages applied to the non-inverting input terminal 43 and the inverting input terminal 47 are compared, and when the voltage level of the non-inverting input terminal 43 is higher, an output is generated and the transistor 45 is made conductive. While transistor 45 is conductive, voltage is applied to solenoids 31 and 33 and motor 35 through resistors 50, 51, and 52.

Therefore, the valves 25 and 36 are opened, and the cleaning liquid in the tank 38 is supplied to the heat exchanger 10 through the valve 36 and the spout 40 by driving the pump 34.
is supplied into the expansion chamber 14 of. For this reason, the inside of the metal tube 15 is cleaned, and this cleaning liquid flows into the shrinkage chamber 16 together with the corrosive substances and passes through the tube 24 to the container 2.
Flow into 3. Since the valve 25 is already open, the condensed water and cleaning water are discharged to the outside through the valve 25. When the corrosive substance concentration in the container 23 falls below a predetermined level, the voltage applied to the non-inverting input terminal 43 of the differential amplifier 44 changes to the inverting input terminal 47.
Since the voltage becomes lower than the voltage of , the output of the differential amplifier 44 is stopped and the transistor 45 becomes non-conductive. Therefore, the solenoids 31, 33 and the motor 3
5 is deenergized, valves 25 and 36 are closed, and supply of the cleaning liquid into the heat exchanger 10 by the pump 34 ends.

As another embodiment of the cleaning liquid supply means used in the present invention, an example in which a bench lily tube 53 is used is shown in FIG. In this example, a reduced cross-section portion 54 is formed at the inlet 13 of the first passage 11, and a pipe 55 communicating with the valve 36 is connected to the reduced cross-section portion 54. Therefore, the exhaust gas flows at a high velocity in the reduced cross-section portion 54 and is in a low pressure state. In this state, when the solenoid 33 is energized and the valve 36 is opened, the cleaning liquid 37 in the tank 38 is automatically sucked into the reduced section section 54 of the heat exchanger 10 without using the pump 34, and is exhausted. It is sprayed into the expansion chamber 14 together with the gas, and the inside of the metal tube 15 is cleaned.

When performing appropriate cleaning in addition to the automatic cleaning described above, the switch 46 is manually pressed. Therefore, the voltage applied to the non-inverting input terminal 43 increases, and the output of the differential amplifier 44 cleans the heat exchanger in the same manner as described above.

Various modifications can be made to the device of this invention. For example, the pipe 24 can be divided into two branches so that the condensed water and the cleaning liquid can be discharged in separate pipes. Further, a drain may be provided at the bottom of the expansion chamber 14.

Furthermore, a transistor 45 and solenoids 31, 33
Or by connecting an individual timer between the motor 35 and
Alternatively, these operating times may be arbitrarily selected by connecting to another power switch. Furthermore, OR gate 42
is omitted, the output of the amplifier 41 is directly connected to the non-inverting input terminal 43 of the differential amplifier 44, the switch 46 is connected in parallel with the transistor 45, and the output of the switch 46 is directly connected to the resistors 50, 5.
1,52 may be applied.

A filter may be provided between the tank 38 and the pump 34 to prevent foreign matter such as scale or dirt from entering the heat exchanger 10 together with the cleaning liquid. In addition, in order to reuse the waste liquid, a circulation pipe line may be used in which the pipe 27 is equipped with a processing device such as a filter, a neutralization tank, or a detergent mixing tank, and the purified liquid is returned to the tank 38 through such a device. can.

The above embodiment shows an example of a shell-and-tube heat exchanger,
It can also be applied to multi-plate heat exchangers.

Effects of the Invention Since the present invention is configured as described above, the heat exchanger can be automatically cleaned and the efficiency of the heat exchanger is not reduced. Moreover, the heat exchanger can be manufactured lightweight and relatively inexpensively. Furthermore, cleaning work by cleaning personnel can be omitted, and the heat exchanger can be thoroughly cleaned in detail. Therefore, the time required for repairing the heat exchanger is significantly reduced, and the life of the heat exchanger can be extended.

[Brief explanation of drawings]

Fig. 1 is a sectional view of a heat exchanger cleaning device according to the present invention; Fig. 2 is an electric circuit diagram showing details of the control circuit; Fig. 3 is a sectional view of another embodiment of the cleaning liquid supply means. show. 10... Heat exchanger, 11... First passage, 12...
...Second passageway, 23...Container, 28...Sensor, 3
9... Comparison circuit, 49... Cleaning liquid supply means.

Claims (1)

[Claims] 1. A water introduction process for introducing condensed water obtained in a heat exchanger into a container; A measurement process for measuring the concentration of a specific component contained in the condensed water introduced into the container; A heat exchanger characterized by comprising: a detection step of detecting that the concentration of a component is at a predetermined level or higher; and a cleaning step of supplying a cleaning liquid into the heat exchanger based on the detection in the detection step. How to clean the utensils. 2. The heat exchanger cleaning method according to claim 1, wherein in the cleaning process, condensed water and cleaning liquid pipes are opened at the same time as the cleaning liquid is supplied. 3. The heat exchanger cleaning method according to claim 1 or 2, wherein the measurement process, detection process, and cleaning process are automatically performed by electrical means. 4. A heat exchanger having a first passage and a second passage through which a first fluid and a second fluid for heat exchange pass separately; a container for storing condensed water obtained in the first passage; and the container. a sensor that generates an electric signal in response to a specific component contained in the condensed water; a comparison circuit that generates a drive signal when the electric signal of the sensor is above a predetermined level; and a heat exchanger that receives the drive signal of the comparison circuit. 1. A cleaning device for a heat exchanger, comprising a cleaning liquid supply means for supplying cleaning liquid into the vessel. 5. The heat exchanger cleaning device according to claim 4, wherein the sensor is a PH sensor. 6. The heat exchanger cleaning device according to claim 4, wherein the comparison circuit includes a differential amplifier. 7. The heat exchanger cleaning device according to claim 4, wherein the cleaning liquid supply means includes a motor energized by the drive signal of the comparator and a pump driven by the motor. 8 The cleaning liquid supply means is the first one of the heat exchanger.
5. The heat exchanger cleaning device according to claim 4, further comprising a bench lily tube formed at an inlet into which fluid flows. 9 The cleaning liquid supply means has a first solenoid valve that controls the outflow of liquid in the container containing condensed water and a second solenoid valve that controls the inflow of the cleaning liquid into the heat exchanger, and the first solenoid valve 7. The heat exchanger cleaning device according to claim 6, wherein the second electromagnetic valve is controlled by the output of the differential amplifier. 10. The heat exchanger cleaning device according to any one of claims 6 to 9, wherein the heat exchanger is inclined at a certain angle with respect to the horizontal.