JPS6321115B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a cleaning method for cleaning the contact surface (heat transfer surface) of each plate of a plate heat exchanger that comes into contact with a heat exchange fluid, without disassembling the heat exchanger. , it is an object of the present invention to provide a cleaning method that allows automatic and repeated cleaning.

In plate heat exchangers in which waste water containing impurities flows through a passage on one side of the plate, after a certain period of use, impurities and limescale contained in the water will adhere to the surface of the plate and cause it to become dirty. , the plates must be cleaned after a certain period of use due to a decrease in heat transfer efficiency. Conventionally, in the case of a small heat exchanger, this cleaning was performed by disassembling the heat exchanger and cleaning the plates individually. However,
For large heat exchangers, it is very difficult to disassemble and reassemble them, and cleaning by the above method requires a great deal of labor and time, and is almost impossible to implement.

On the other hand, for heat exchangers other than plate heat exchangers, such as those using contact tubes, cleaning methods have already been developed for cleaning the inside of the heat exchanger without disassembling the heat exchanger. This is a sponge with a specific gravity that is lighter than that of water, and is made into balls of an appropriate size, and many of these sponge balls are poured into the contact tube along with water.
This is a cleaning method in which a sponge ball is brought into contact with the inner surface of the contact tube during the flow to scrape off dirt such as limescale adhering to the inner surface of the tube.The shape of the sponge ball after cleaning is relatively small. Since it is large, it is collected in a container with numerous drainage holes, such as a basket, and prepared for the next cleaning.

The above cleaning method is preferable because it allows cleaning the inside of the heat exchanger without disassembling the heat exchanger, so it has good workability and is preferred.However, it is difficult to immediately apply this cleaning method to plate heat exchangers, and there are various There was a problem. In other words, unlike the tube type heat exchanger, the plates are arranged at very narrow intervals of 4 to 5 mm to increase transmission efficiency, and the heat transfer surfaces of the plates have various types of heat exchangers. Because of the unevenness, it is impossible to flow large sponge balls, and in order to carry out the method described above, it is necessary to flow very small pellets with a diameter of about 1 to 2 mm. However, it is very difficult to collect small pellets like the ones mentioned above, and if the pellets are simply collected in a container with fine holes that do not allow the pellets to pass through, the container will quickly become clogged, making it impossible to dehydrate the pellets. could not be recovered, and the cleaning method described above could not be applied.

The present invention has been developed in view of the problems of the conventional cleaning methods described above and in order to improve and eliminate them.
That is, in the present invention, pellets such as beads having a diameter smaller than the spacing between the plates of a plate heat exchanger and a specific gravity smaller than the specific gravity of water are passed together with water, and the pellets are spread onto the contact surfaces of the plates. The pellets are washed by colliding with the surface of the plate using the turbulent flow of water that is perpendicular to the plate. A funnel-shaped filtration tank with greater resistance on the outflow side than the other side flows into the cyclone filtration tank installed in the housing, where most of the water in the mixed liquid is drained from the filtration tank through the housing, and the pellets are transferred to the filtration tank. The pellets containing a small amount of water are discharged from the center of the pellet and flowed into a strainer with a double-tube structure consisting of an outer tube and an inner tube with fine holes that do not allow pellets to pass through. During rewashing, part of the washing water supplied to the heat exchanger is pumped back into the strainer to drain out the pellets accumulated in the strainer, and the pellets are collected in the washing water. is supplied to the heat exchanger together with the pellets, and until the pellets have finished flowing out, only the waste water is discharged from the cyclone, and the pellets are retained in the filtration tank.
In this cleaning method, after the pellets have flowed out, the pump is stopped and only water for cleaning is supplied to the heat exchanger, and the pellets in the filtration tank are allowed to flow into the strainer and collected.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The structure of the present invention will be described below with reference to embodiments shown in the drawings.

The drawing shows an outline of the cleaning method of the present invention, in which 1 is a plate heat exchanger;
It has an inflow head 2 and an outflow head 3 for the fluid, and is further branched to the outflow head 3 to collect the pellets 5 after washing.
A discharge port 4 is formed to discharge a mixed liquid of water and water.

6 is a cyclone that removes excess water from the mixed liquid discharged from the heat exchanger 1 and collects some of the pellets floating in the water to perform a first-stage concentration action; and a funnel that generates a vortex flow inside the housing 7. The filter tank 8 has a built-in filter tank 8, and the peripheral wall of the filter tank 8 is provided with numerous fine holes 9 of a size that does not allow the pellets 5 to pass through. An inlet 10 is formed to allow water to flow in in the tangential direction of the inner circumference of the tank, a first outlet 11 is formed at the lower side to allow water to flow in, and a first outlet 11 is formed at the lower side to allow water to flow in, and a first outlet 11 is formed at the bottom side to allow water to flow in from the filtration tank 8. Two discharge ports 12 are formed. 13 is a strainer that collects the mixed liquid concentrated in the cyclone 6, removes moisture, further concentrates it, collects and accumulates only the pellets 5, and drains the pellets 5 as needed; It has a double tube structure consisting of a tube 15, an inner tube 14 and an outer tube 1.
In addition to forming an accumulation layer 16 for accumulating pellets 5 between the inner tube 14 and the outer tube 15, numerous fine holes 17 are formed in the peripheral wall of the inner tube 14 to prevent the pellets 5 from passing through, and the outer tube 15 has a concentrated mixture layer 16 formed on the side surface of the outer tube 15. An inlet 18 through which the liquid flows into the accumulation layer 16 and an outlet 19 through which the pellets 5 and water flow out from the accumulation layer 16 are formed, and the lower surface is formed to allow water removed from the concentrated mixed liquid during collection to flow out or to collect the pellets. A flow port 20 is formed to supply water during supply. In the illustrated example, the strainer 13 is configured to accumulate the pellets 5 between the inner tube 14 and the outer tube 15, but another strainer configured to accumulate the pellets in the inner tube 14 may be used. A large number of strainers 13 are arranged in parallel, and when a sufficient amount of pellets is accumulated in one strainer, the strainer is switched to allow pellets to be accumulated in the next strainer.
The outlet 4 of the heat exchanger 1 and the inlet 10 of the cyclone 6 are connected by a pipe 21, the first outlet 11 of the cyclone 6 is connected to a drain pipe 22, and the second outlet 12 and the strainer 13 are connected to each other. The inlet 18 of
4, the flow port 20 of the strainer 13 and the drain pipe 22 are connected by a pipe 26 via a throttle valve 25, and a part of the pipe 26 is branched to supply water to the heat exchanger 1. Throttle valve 28 to water supply pipe 27
and the pump P via a branch pipe 29, and the outlet 19 is connected to the water supply pipe 27 via a throttle valve 30 via a pipe 31, whereby the cyclone 6
and the strainer 13 are connected in parallel, and both are connected between the outflow side and the inflow side of the heat exchanger 1.

When heat exchange is performed in the heat exchanger 1 for a certain period of time and the surface of each plate of the heat exchanger 1 becomes dirty with limescale etc., the normal heat exchange path is closed and the water supply pipe 2
Cleaning water is supplied from 7 to the heat exchanger 1, and at the same time, the throttle valve 23 of the pipe 24 and the throttle valve 25 of the pipe 26 are closed, and the throttle valve 28 of the branch pipe 29 and the throttle valve 30 of the pipe 31 are opened. , the pump P is operated to forcibly supply high-pressure water from the water supply pipe 27 to the flow port 20 of the strainer 13 via the branch pipe 29. Then, this high-pressure water flows into the accumulation layer 16 from the hole 17 of the inner pipe 14, and the pellets 5 previously accumulated in this accumulation layer are synthesized, preferably having a diameter of about 1 to 2 mm and a specific gravity lower than that of water. The resin pellets 5 are pushed out to the outlet 19, become a mixed liquid, flow through the pipe 31, and flow into the water supply pipe 27 to the heat exchanger 1.
supplied to The numerous pellets 5 supplied to the heat exchanger 1 immediately after the start of cleaning are carried away by the turbulent flow of water generated between the plates and collide with the surfaces of the plates.
Remove any dirt adhering to the surface. The pellets 5 that have flowed between the plates are discharged from the drain port 4 together with water and dirt, and flow into the filter layer 8 of the cyclone 6 via the pipe 21 and the inlet port 10. The mixed liquid that has flowed into the filtration layer 8 generates a swirling flow here,
Water and dirt with higher specific gravity are directed outward from holes 9 drilled in the filtration layer 8 to a first outlet 11 and a drain pipe 2.
2 and is discharged to the outside. On the other hand, the pellets 5 having a light specific gravity are collected and retained in the center. When all the pellets 5 in the strainer 13 are drained out,
The operation of the pump P is stopped, the throttle valve 28 of the branch pipe 29 and the throttle valve 30 of the pipe 31 are closed, and the pipe 24 is closed.
The throttle valve 23 and the throttle valve 25 of the pipe 26 are opened, and water is continuously supplied from the water supply pipe 27 to the heat exchanger. Then, the pellets 5 that had remained in the filter layer 8 are concentrated and become a concentrated mixed liquid together with a small amount of water, which is discharged from the second outlet 12 and discharged from the pipe 2.
4 and the inlet 18 into the storage layer 16 of the strainer 13. After the throttle valve 23 is opened, the mixed liquid discharged from the heat exchanger 11 flows from the cyclone 6 to the strainer 13 while being concentrated, and the concentrated mixed liquid flowing into the strainer 13 is concentrated in the accumulation layer 16. The pellets 5 that are piled up and do not pass through the holes 17 of the inner tube 14 are collected one by one and accumulated in the accumulation layer 16, and the water attached to the pellets 5 is squeezed and passes through the holes 17 of the inner tube 14 and The water flows from the pipe 14 through the flow port 20 and the pipe 26 to the drain pipe 22, from which it is drained to the outside. When sufficient accumulation has occurred in this manner, the throttle valve 23 of the pipe 24 and the throttle valve 25 of the pipe 26 are closed, and the concentrated mixed liquid drained from the cyclone 6 is supplied to the next strainer to collect the pellets. The amount of pellets 5 accumulated in the strainer 13 is determined by
Attach pressure gauges P ₁ and P ₂ to 0 and 0 respectively, and install both pressure gauges P ₁ ,
It is determined by the difference P ₁ -P ₂ of P ₂ , and when this value reaches a predetermined value, the collection operation of the strainer 13 concerned is stopped and the next strainer is made to perform collection.

In the above cleaning method, the pellets 5 used for cleaning the heat exchanger 1 have a specific gravity lower than that of water, so the pellets 5 that are flushed away with water always float in the water and are washed away from each pipe and the heat exchanger 1. It flows without sedimentation within the container, ensuring a reliable cleaning action. In addition, the mixed liquid discharged from the heat exchanger 1 is sufficiently stirred by the swirling flow in the cyclone 6, and the pellets 5, which have a light specific gravity, are collected in the center of the vortex. 21 and the pipe 24 connected to the second discharge port 12 have different diameters, and the flow rate is greatly reduced, so most of the water is discharged from the hole 9, and the pellets 5 collected in the center are It is discharged from the outlet 12 of No. 2 in a concentrated state. Further, since the pellets 5 are collected in the center by the swirling flow, they do not adhere to the wall surface of the filter tank 8 and cause clogging. Furthermore, the concentrated liquid mixture supplied from the cyclone 6 to the strainer 13 has very little water content, and the amount of water discharged from the strainer 13 is small, so even if the inner tube 14 becomes clogged due to the accumulation of pellets 5, the pellets can be fed without any problem. can be collected. Furthermore, when high pressure water is supplied to the strainer 13 from the flow path 20, the pellets 5 accumulated in the strainer 13 are removed.
can be supplied to the heat exchanger 1 again for cleaning, and cleaning can be performed without disassembling the heat exchanger 1 as needed.

As explained above, in the present invention, during cleaning, a part of the cleaning water supplied to the heat exchanger is made to flow back to the strainer using a pump, and the minute pellets accumulated in the strainer are mixed with the cleaning water. The pellets are supplied to the plate heat exchanger, and after the pellets flow out, the pump is stopped and only water for washing is supplied to the heat exchanger.Since the pellets are not passed through the pump, the pellets are not damaged. In addition, the pump is used only to drain the pellets, and collection is performed only by the flow of washing water, resulting in a high energy-saving effect. Furthermore, in the present invention, the mixed solution of water and pellets after washing is once concentrated in a cyclone, and then only the pellets are collected in a thretner, and the cyclone is narrower on the outflow side than on the inflow side of the mixed solution. Most of the water in the mixed liquid flows out from the filtration tank to the housing and is discharged, and the vortex flow inside the filtration tank collects pellets with a lighter specific gravity than water in the center and discharges them. The pellets do not adhere to the tank and cause clogging, the pellets do not rub against the filter tank and are damaged, and the mixed liquid is sufficiently concentrated. Furthermore, since the mixed liquid flowing into the strainer has low water content and low water pressure, the pellets are not pressed strongly against the inner tube of the strainer, so there is no pressure loss. Furthermore, the inner tube gradually becomes clogged due to the accumulation of pellets, but since the amount of water drained is small, the drainage is sufficient and the pellets are recovered without any problems.

In this way, in the present invention, the mixed solution of pellets and cleaning water is circulated through the plate heat exchanger with a small amount of power, and the plates are cleaned.
The mixed solution after cleaning can be concentrated in multiple stages and recovered without damaging the pellets, allowing the pellets to be reused over a long period of time and cleaning plate heat exchangers easily and effectively. At the same time, the running costs associated with cleaning can be significantly reduced.

[Brief explanation of the drawing]

The drawings are diagrams showing an outline of a method for cleaning a plate heat exchanger according to the present invention. 1... Plate heat exchanger, 5... Pellet,
6... Cyclone, 8... Filtration tank, 13... Strainer, 16... Accumulation tank.

Claims (1)

[Claims] 1 It has a double structure consisting of an outer tube and an inner tube with fine holes that do not allow pellets to pass through, and between the outer tube and the inner tube, there is a space between the outer tube and the inner tube that has a specific gravity lower than that of water and is more sufficient than the plate spacing of the heat exchanger. This circuit is constructed by connecting in parallel a strainer that accumulates small pellets and a cyclone that has a funnel-shaped filtration tank in its housing that has fine holes that do not allow pellets to pass through and has a higher resistance on the outflow side than on the inflow side. It is installed between the inflow and outflow sides of a plate heat exchanger, and during cleaning, a part of the cleaning water flows back into the strainer using a pump, and the pellets in the strainer flow out together with the cleaning water. The mixed liquid containing pellets is supplied to the inflow side and discharged from the outflow side of the heat exchanger, and is passed through a cyclone to discharge only the waste water to the outside.The pellets are retained in the filtration tank of the cyclone, and the pellets in the strainer are completely removed. After the pellets have flowed out, the pump is stopped, and from then on, only water for cleaning is supplied to the heat exchanger. During this time, the pellets are collided with the heat transfer surface of the plate of the heat exchanger to perform cleaning. After the pellets flow out from the strainer, ,
A plate heat exchanger that discharges the pellets in the cyclone's filtration tank from the center of the filtration tank and flows into the strainer, accumulating the pellets in the strainer and discharging water from the inner tube to the outside. cleaning method.