WO2005124261A1

WO2005124261A1 - A heat exchanger aoto cleaning system using ejector

Info

Publication number: WO2005124261A1
Application number: PCT/KR2005/001793
Authority: WO
Inventors: Won Seal Seol
Original assignee: Won Seal Seol
Priority date: 2004-06-15
Filing date: 2005-06-14
Publication date: 2005-12-29
Also published as: JP2008502871A

Abstract

Disclosed is herein an automatic cleaning system which cleans heat transfer tubes of a heat exchanger (120) using cleaning balls . The automatic cleaning system includes the heat exchanger (120) , a ball separator (130) which is coupled to an outlet pipe (124) of the heat exchanger, a ball supplying pipe (137) and a ball recovery pipe (138) . The system further includes a cleaning ball storage tank (14) communicating with both the ball supplying pipe and the ball recovery pipe, and an ejector (150) communicating with the cleaning ball storage tank (140) . The system further includes a bypass pipeline (160) having a fluid inlet guide pipe (161) and a fluid outlet guide pipe (163) , a circulation pump (162) mounted on the fluid inlet guide pipe, and a motor- operated valve (164) mounted on the fluid outlet guide pipe (163) .

Description

[DESCRIPTION]

[invention Title] A HEAT EXCHANGER AUTO CLEANING SYSTEM USING EJECTOR

[Technical Field] The present invention relates, in general, to automatic cleaning systems which supply cleaning balls to heat exchangers using the combination of a pump and an ejector, thus removing contaminants stuck to inner surfaces of heat transfer tubes in the heat exchangers and, more particularly, to an automatic heat exchanger cleaning system (hereinafter, referred to simply as an automatic cleaning system) which supplies fluid to a cleaning ball storage tank, containing cleaning balls therein, using a unidirectional circulation pump so that the cleaning balls are supplied into heat transfer tubes of a heat exchanger by the supplied fluid, and the cleaning balls pass through the heat transfer tubes along with the fluid, thus removing scales from the heat transfer tubes, and which has a structure such that, when it is desired to recover the cleaning balls, a motor-operated valve, provided at an end of the ejector, is opened to supply fluid from the circulation pump to the ejector, and the ejector discharges the fluid using a nozzle provided in the ejector, thus reducing the pressure in the cleaning ball storage tank, thereby the cleaning balls are recovered into the cleaning ball storage tank, so that the time required to supply and recover the cleaning balls can be arbitrarily adjusted according to the conditions at a system installation site, thus easily executing the supply and recovery of the cleaning balls, and which solves the problem of the cleaning balls supplied into a ball separator becoming temporarily jammed in conventional arts, thus preventing pressure from being lost and the cleaning balls from wearing due to the temporary cleaning ball jamming phenomenon, and which markedly reduces the probability of malfunction and the installation costs of the circulation pump, compared to conventional arts which must periodically change the direction of rotation of a circulation pump between normal and reverse directions for the supply and recovery of cleaning balls .

[Background Art] Generally, shell and tube type heat exchangers, in which a plurality of tubes is disposed in a shell, have been used in refrigerant systems or chemical plants. In such a heat exchanger, heat is transferred between air and fluid, to be used as a heat transfer medium, in a cooling tower. If such a heat exchanger is used over a long period, foreign materials, such as microbes and dust in air, are mixed with the fluid and collect on the inner surfaces of tubes of the heat exchanger, thus causing adhesive impurities, such as scales and slime, on the inner surfaces of the tubes. Due to this, the performance of the heat exchanger deteriorates and its lifetime is reduced. Therefore, it is required to remove adhesive impurities. As methods for removing scales or slime collected on the inner surfaces of the tubes of the heat exchanger, heat exchanger tube cleaning methods, in which balls such as sponge balls (hereinafter, referred to simply as cleaning balls) are forcibly passed through tubes so as to remove adhesive impurities from the inner surface of the tubes, were proposed in US Patent No. 3919372, Japanese Patent Laid-open Publication No. Sho. 63-238397, US Patent No. 486521, Korean Patent Laid-open Publication No. 1996- 7006061, Korean Utility Model Registration No. 227922, and Korean Utility Model Registration No. 237353. Among them, a technique disclosed in Korean Patent Laid-open Publication No. 1996-7006061 will be described herein below. This technique relates to a cleaning system for cleaning the inside of a fluid conducting tube (hereinafter, referred as a heat transfer tube) and an associated apparatus. As shown in FIG. 1, when a compressed air supply valve 54, which is coupled to a compressor 50, is opened, air is supplied from the compressor 50 into a cleaning ball storage tank 40. Then, cleaning balls 42 and fluid, which have been in the cleaning ball storage tank 40, are lifted by the pressure of the supplied air. Subsequently, the cleaning balls 42 and the fluid are supplied into the heat transfer tubes 22 of the heat exchanger 20 through a guide pipe 35, which connects the cleaning ball storage tank 40 to an inlet pipe 10 of the heat exchanger 20, thus cleaning the heat transfer tubes 22. To recover the cleaning balls 42 after the cleaning process is conducted, a compressed air discharge valve 56, which is mounted on an air outlet guide pipe 53 provided at a predetermined position on the cleaning ball storage tank 40, is opened so that the air, which was in the cleaning ball storage tank 40, is discharged to the outside. Then, the cleaning balls 42 are recovered into the cleaning ball storage tank 40 by the difference in pressure between a ball separator 30, which is coupled to an outlet pipe 24 of the heat exchanger 20, and the cleaning ball storage tank 40, which is connected to the ball separator 30 through a connection pipe 34. In the drawing, the reference numeral 32 denotes a cylindrical sieve, and 37 denotes a valve. However, in the conventional cleaning system using compressed air, if the compressed air supply valve 54 is opened for a long time, air is undesirably drawn into the inlet pipe 10 of the heat exchanger 20. Conversely, if the opening time of the compressed air supply valve 54 is short, the cleaning balls 42 may not be completely supplied into the heat transfer tubes 22 of the heat exchanger 20. Particularly, to reduce the pressure in the cleaning ball storage tank 40 for recovering the cleaning balls 42, a large amount of fluid, which has been in the cleaning ball storage tank 40, must be discharged as waste water through a drain pipe. Furthermore, when the compressed air supply valve 54 and the compressed air discharge valve 56 are opened or closed to supply or recover the cleaning balls 42, noise may occur in a check valve 36 due to a water hammer phenomenon caused when the air pressure is suddenly increased or decreased. In serious case, there is a problem of damage to the check valve 36. In addition, when recovering the cleaning balls 42 after executing the cleaning process, the process of recovering the cleaning balls 42 cannot be executed over a long period of time due to the limited volume of the cleaning ball storage tank 40. Therefore, the cleaning balls 42 may not be completely recovered in the cleaning ball storage tank 40. Particularly, because the amount of cleaning balls 42 discharged from the outlet pipe 24 of the heat exchanger into the ball separator 30 is greater than the amount of recovered cleaning balls 42, in other words, because the diameter of the connection pipe 34, which is coupled at a central portion to an end of the ball separator 30, is smaller than the diameter of the ball separator 30, a temporary phenomenon occurs in which the cleaning balls 42 clog the ball separator 30. Due to the clogging phenomenon of the cleaning balls 42, pressure loss occurs in the ball separator 30. As a result, flow resistance of the connection pipe, which is coupled at a central portion to an end of the ball separator 30, increases, thereby increasing wear of the cleaning balls 42. Moreover, as a drive means for supplying the cleaning balls 42 from the cleaning ball storage tank 40 into the heat transfer tubes 22 of the heat exchanger 20 and for recovering the cleaning balls 42 in the cleaning ball storage tank 40, a separator air supplying pipe 52 and the compressor 50, which increase the pressure of the cleaning ball storage tank 40, are required, and a decompression device, which reduces the pressure of the cleaning ball storage tank 40, is required. As such, due to the additional equipment, there is difficulty in commercializing the cleaning system. Furthermore, there is a problem of an increase in the cost of the system. In addition, the conventional system is problematic in that, because the supply and recovery rates of the cleaning balls 42 are reduced due to the limited volume of the cleaning ball storage tank 40, the efficiency of removing scales stuck to the inner surface of the heat transfer tubes 22 is reduced. In an effort to overcome the above-mentioned problems, a system of cleaning heat transfer tubes 22 provided in a condenser was proposed in Korean Utility Model Registration No. 227922. As shown in FIG. 2, in this cleaning system, fluid is supplied by the normal rotation of a circulation pump 45 from an inlet pipe 10 of a heat exchanger 20 into a cleaning ball storage tank 40 through a fluid supplying pipe 11, so that cleaning balls 42 rise in the cleaning ball storage tank 40. Thereafter, the cleaning balls 42 are supplied into the heat transfer tubes 22 of the heat exchanger 20 through a ball carrying pipe 13, which connects the upper end of the cleaning ball storage tank 40 to the inlet pipe 10 of the heat exchanger 20, thus cleaning the heat transfer tubes 22. When the cleaning balls 42 are recovered after executing the cleaning process, the circulation pump 45 is rotated in a reverse direction. Thereby, the cleaning balls 42 and fluid are discharged from an outlet pipe 24 of the heat exchanger 20 into a ball separator 30. The cleaning balls 42 and fluid are recovered by suction force of the circulation pump 45 in the cleaning ball storage tank 40 via a ball recovery pipe 34, which connects the cleaning ball storage tank 40 to a cylindrical sieve 32, which is disposed in the ball separator 30. Subsequently, the fluid, which is recovered along with the cleaning balls 42, passes through a filter 43, which is disposed between the cleaning ball storage tank 40 and the circulation pump 45, thus filtering out scales . Thereafter, the fluid is again supplied into the inlet pipe 10 of the heat exchanger 20 through the fluid supplying pipe 11. In the drawing, the reference numerals 14 and 35 denote valves. As such, in the conventional cleaning system, as a drive means for supplying the cleaning balls 42 from the cleaning ball storage tank 40 into the heat transfer tubes 22 of the heat exchanger 20 and for recovering the cleaning balls 42 in the cleaning ball storage tank 40, the reversible circulation pump 45 is used. However, because the reversible circulation pump 45 is more expensive than a unidirectional pump, the cost of the system is increased. Moreover, in the process of recovering the cleaning balls 42, the cleaning balls 42, having passed through the heat transfer tubes 22 of the heat exchanger 20, are collected in the cylindrical sieve 32 of the ball separator 30 and are then recovered in the cleaning ball storage tank 40 by the suction force of the circulation pump 45 which rotates in a reverse direction. Therefore, the resistance to the flow of the fluid increases. Furthermore, due to friction among the cleaning balls 42, wear occurs. As a result, the lifetime of the cleaning balls 42 is reduced.

[Disclosure] [Technical Problem] Accordingly, the present invention has been made keeping in mind the above problems occurring in the prior art, and an object of the present invention is to provide an automatic heat exchanger cleaning system in which, while a motor-operated valve, mounted on a pipe extending from an outlet of an ejector, is closed, fluid is supplied to a cleaning ball storage tank, containing cleaning balls therein, by a unidirectional circulation pump, so that the cleaning balls are supplied into heat transfer tubes of a heat exchanger by the supplied fluid, and the cleaning balls pass through the heat transfer tubes along with the fluid, thus removing scales from the heat transfer tubes, and which has a structure such that, when it is desired to recover the cleaning balls, a motor-operated valve, provided at an end of the ejector, is opened to supply fluid from the circulation pump to the ejector, and the ejector discharges the fluid using a nozzle provided in the ejector, thus reducing the pressure in the cleaning ball storage tank, thereby the cleaning balls are recovered into the cleaning ball storage tank, so that the time required to supply and recover the cleaning balls can be arbitrarily adjusted according to the conditions at a system installation site, thus easily executing the supply and recovery of the cleaning balls, and which solves the problem of the cleaning balls supplied into a ball separator becoming temporarily jammed in the conventional arts, thus preventing pressure from being lost and the cleaning balls from wearing due to the temporary cleaning ball jamming phenomenon. Another object of the present invention is to provide an automatic heat exchanger cleaning system which uses a unidirectional circulation pump as a pump for supplying and recovering the cleaning balls into and from the heat transfer tubes of the heat exchanger, thus markedly reducing the cost of the system, compared with conventional arts which supply and recover cleaning balls using an expensive reversible circulation pump.

[Technical Solution] In a first embodiment of the present invention, an automatic heat exchanger cleaning system includes : a heat exchanger having an inlet pipe at a first end thereof and an outlet pipe at a second end thereof, with a plurality of heat transfer tubes provided in the heat exchanger; a ball separator coupled to the outlet pipe of the heat exchanger and having therein a separator plate to separate cleaning balls from fluid discharged from the outlet pipe; a ball supplying pipe and a ball recovery pipe respectively coupled to the inlet pipe of the heat exchanger and a ball outlet of the ball separator so as to supply and recover the cleaning balls into the heat exchanger and a cleaning ball storage tank; the cleaning ball storage tank communicating with both the ball supplying pipe and the ball recovery pipe in parallel, with a collection net provided in the cleaning ball storage tank to collect the cleaning balls; an ejector communicating with a lower end of the cleaning ball storage tank through a supply and recovery control pipe, so that, when the ejector discharges a fluid supplied from a circulation pump, pressure of the cleaning ball storage tank is reduced, thereby the cleaning balls are recovered into the cleaning ball storage tank; a bypass pipeline having a fluid inlet guide pipe and a fluid outlet guide pipe such that the fluid flows from a fluid discharge pipe via the ejector and reenters the fluid discharge pipe; the circulation pump mounted on the fluid inlet guide pipe and supplying the fluid to the ejector in one direction, thus realizing the supply and recovery of the cleaning balls; and a motor-operated valve mounted on the fluid outlet guide pipe extending from an outlet of the ejector so that the cleaning balls are supplied or recovered by an ON/OFF operation of the motor-operated valve . In a second embodiment, an automatic heat exchanger cleaning system includes : a heat exchanger having an inlet pipe at a first end thereof and an outlet pipe at a second end thereof, with a plurality of heat transfer tubes provided in the heat exchanger; a ball separator coupled to the outlet pipe of the heat exchanger and having therein a separator plate to separate cleaning balls from fluid discharged from the outlet pipe; a ball supplying pipe and a ball recovery pipe respectively connected to an outlet and an inlet of a cleaning ball storage tank, the ball recovery pipe being connected to a ball outlet of the ball separator, so that the cleaning balls circulate through the heat exchanger or are recovered into the cleaning ball storage tank; the cleaning ball storage tank communicating with both the ball supplying pipe and the ball recovery- pipe, with a collection net provided in the cleaning ball storage tank to collect the cleaning balls; a supply and recovery control pipe connected both to a lower end of the cleaning ball storage tank and to the ball supplying pipe such that, when an ejector discharges fluid to recover the cleaning balls, fluid, which has been in the cleaning ball storage tank, is supplied to the ball supplying pipe; the ejector connected to the ball supplying pipe and ejecting fluid supplied from a circulation pump to reduce pressure in the ball supplying pipe or in the supply and recovery control pipe, thereby circulating the cleaning balls through the heat exchanger or recovering the cleaning balls in the cleaning ball storage tank; a bypass pipeline having a fluid inlet guide pipe and a fluid outlet guide pipe such that the fluid flows from the inlet pipe via the ejector and reenters the inlet pipe; the circulation pump mounted on the fluid inlet guide pipe and supplying the fluid to the ejector in one direction, thus realizing the supply and recovery of the cleaning balls; and motor-operated valves mounted on the ball supplying pipe and the supply and recovery control pipe so that the cleaning balls are supplied or recovered according to ON/OFF operation of the motor-operated valves . In a third embodiment, an automatic heat exchanger cleaning system includes : one or more heat exchangers each having an inlet pipe at a first end thereof and an outlet pipe at a second end thereof, with a plurality of heat transfer tubes provided in each of the heat exchangers; a ball separator coupled to the outlet pipes of the heat exchangers and having therein a separator plate to separate cleaning balls from fluid discharged from the outlet pipes; a ball supplying pipe and a ball recovery pipe respectively connected to an outlet and an inlet of a cleaning ball storage tank, the ball recovery pipe being connected to a ball outlet of the ball separator, so that the cleaning balls circulate through the heat exchangers or are recovered into the cleaning ball storage tank; the cleaning ball storage tank communicating with both the ball supplying pipe and the ball recovery pipe, with a collection net provided in the cleaning ball storage tank to collect the cleaning balls; a supply and recovery control pipe connected both to a lower end of the cleaning ball storage tank and to the ball supplying pipe such that, when ejectors eject fluid to recover the cleaning balls, fluid, which has been in the cleaning ball storage tank, is supplied to the ball supplying pipe; one or more ejectors connected to the ball supplying pipe and discharging fluid supplied from a circulation pump to reduce pressure in the ball supplying pipe or in the supply and recovery control pipe, thereby circulating the cleaning balls through the heat exchangers or recovering the cleaning balls in the cleaning ball storage tank; a multi-type bypass pipeline having one or more fluid inlet guide pipes and fluid outlet guide pipes such that fluid flows from the inlet pipes via the ejectors and reenters the inlet pipes coupled to the ejectors; the circulation pump mounted on the fluid inlet guide pipe and supplying the fluid to the ejectors in one direction, thus realizing the supply and recovery of the cleaning balls; and motor-operated valves mounted on the ball supplying pipe, the supply and recovery control pipe and the fluid inlet guide pipes, which connect the ejectors to the circulation pump, so that the cleaning balls are supplied or recovered according to ON/OFF operation of the motor-operated valves, and fluid is selectively supplied to the ejectors according to ON/OFF operation of the motor- operated valves . In the first embodiment, the cleaning ball storage tank may have a hollow cylindrical shape and include: an outlet provided at a predetermined position on an upper end of the tank and coupled to the ball supplying pipe and the ball recovery pipe; and an inlet provided on a lower end of the tank at a predetermined position facing the outlet and communicating with the ejector through the supply and recovery control pipe, so that flow resistance of up- flowing fluid to be discharged from the inlet through the outlet is reduced. Furthermore, the automatic heat exchanger cleaning system of the first embodiment may further include check valves provided on the ball supplying pipe and the ball recovery pipe so as to prevent backflow of the cleaning balls during the cleaning ball supplying or recovering process . In the second embodiment, the cleaning ball storage tank may be constructed such that fluid drawn into the cleaning ball storage tank through the inlet becomes turbulent and is discharged along with the cleaning balls through the outlet, thus supplying the cleaning balls. Furthermore, the cleaning ball storage tank of the second embodiment may have a hollow cylindrical shape and include: the inlet provided at a predetermined position on an upper end of the tank and coupled to the ball recovery pipe; the outlet provided on the upper end of the tank at a position opposite the inlet on the same horizontal line as the inlet and coupled to the ball supplying pipe, such that fluid to be discharged from the inlet through the outlet becomes turbulent; and a fluid discharge hole formed at a central position in a lower end of the tank so as to discharge fluid from the cleaning ball storage tank to the supply and recovery control pipe, thus recovering the cleaning balls. In the first through third embodiments, the separator plate may have an elliptical shape, a lower end of which extends in a rectangular shape, is disposed and inclined in the ball separator, and may include a slot formed through the separator plate in the direction in which fluid flows . The automatic heat exchanger cleaning system may further include a direction change guide body provided on an edge of the separator plate adjacent to the ball outlet of the ball separator so as to guide the cleaning balls to be discharged to the ball outlet. In the first through third embodiments, the ejector may include therein a nozzle to discharge fluid supplied from the circulation pump. In the first through third embodiments, the cleaning ball storage tank may include a side glass on an upper surface thereof to allow a user to observe a flow and a rate of wear of the cleaning balls. In the third embodiment, the inlet pipes and the ball supplying pipes may form a branching pipe structure communicating with one or more ejectors in a multiple arrangement, and the outlet pipes, coupled to the ball separator, form a branching pipe structure. The motor-operated valves may be mounted on the fluid inlet guide pipes, which connect the ejectors to an outlet of the circulation pump, so as to allow a user to control the fluid inlet guide pipes according to a purpose. [Advantageous Effects] In an automatic heat exchanger cleaning system of the present invention, while a motor-operated valve, mounted on a pipe extending from an outlet of an ejector, is closed, fluid is supplied to a cleaning ball storage tank, containing cleaning balls therein, by a unidirectional circulation pump, so that the cleaning balls are supplied into heat transfer tubes of a heat exchanger by the supplied fluid, and the cleaning balls pass through the heat transfer tubes along with the fluid, thus removing scales from the heat transfer tubes. Furthermore, the present invention has a structure such that, when it is desired to recover the cleaning balls, a motor-operated valve, provided at an end of the ejector, is opened to supply fluid from the circulation pump to the ejector, and the ejector discharges the fluid using a nozzle provided in the ejector, thus reducing the pressure in the cleaning ball storage tank, thereby recovering the cleaning balls into the cleaning ball storage tank. Therefore, the time required to supply and recover the cleaning balls can be arbitrarily adjusted according to the conditions at a system installation site, thus easily executing the supply and recovery of the cleaning balls. As well, the present invention solves the problem of the cleaning balls supplied into a ball separator becoming temporarily jammed in the conventional arts, thus preventing pressure being lost and the cleaning balls from wearing due to the temporary cleaning ball stopping phenomenon. Moreover, the preset invention uses a unidirectional circulation pump as a pump for supplying and recovering the cleaning balls into and from the heat transfer tubes of the heat exchanger, thus markedly reducing the cost of the system, compared with conventional arts which supply and recover cleaning balls using an expensive reversible circulation pump. In addition, the present invention supplies and recovers the cleaning balls using the combination of a general unidirectional circulation pump and an ejector. Accordingly, the construction of the system is simple, so that the probability of malfunction is markedly reduced. As well, the space required to install the system is reduced, and the manufacturing costs of the system are reduced.

[Description of Drawings] FIG. 1 is a schematic view showing a conventional fluid conducting tube cleaning system; FIG. 2 is a schematic view showing a conventional fluid carrying tube cleaning system; FIG. 3 is a schematic view of an automatic heat exchanger cleaning system, according to a first embodiment of the present invention; FIG. 4 is a sectional view and a detailed view respectively showing a ball separator and a separator plate of the automatic cleaning system, according to the present invention; FIG. 5 is views showing a cross-section of a cleaning ball storage tank of the automatic cleaning system and showing the flow of fluid in the cleaning ball storage tank, according to the present invention; FIG. 6 is a sectional view showing an ejector of the automatic cleaning system according to the present invention; FIG. 7 is a view of an automatic heat exchanger cleaning system, according to a second embodiment of the present invention; FIG. 8 is a sectional view and a plan sectional view showing a cleaning ball storage tank of the automatic cleaning system of Fig. 7; FIG. 9 is a view of an automatic heat exchanger cleaning system, according to a third embodiment of the present invention; and FIG. 10 is a view showing the operation of the automatic cleaning system according to the present invention.

[Best Mode] Hereinafter, an automatic heat exchanger cleaning system of the present invention will be explained in detail . FIG. 3 is a schematic view of the automatic heat exchanger cleaning system, according to a first embodiment of the present invention. FIG. 4 is a sectional view and a detailed view respectively showing a ball separator and a separator plate of the automatic cleaning system of the present invention. FIG. 5 is views showing a cross-section of a cleaning ball storage tank of the automatic cleaning system and showing the flow of fluid in the cleaning ball storage tank, according to the present invention. Furthermore, FIG. 6 is a sectional view showing an ejector of the automatic cleaning system according to the present invention. As shown in FIG. 3, the automatic cleaning system of the present invention includes a heat exchanger 120 which has an inlet pipe 110 at a first end thereof and an outlet pipe 124 at a second end thereof. A plurality of heat transfer tubes 122 is provided in the heat exchanger 120. The automatic cleaning system further includes a ball separator 130 which is coupled to the outlet pipe 124 of the heat exchanger 120 and has therein a separator plate 132 to separate cleaning balls 142 from fluid discharged from the outlet pipe 124, and a ball supplying pipe 137 and a ball recovery pipe 138 which are respectively coupled to the inlet pipe 110 of the heat exchanger 120 and a ball outlet 135 of the ball separator 130 so as to supply the cleaning balls 142 into the heat exchanger 120 and recover them into the cleaning ball storage tank 140. The automatic cleaning system further includes the cleaning ball storage tank 140 which communicates with both the ball supplying pipe 137 and the ball recovery pipe 138 in parallel, with a collection net 141 provided in the cleaning ball storage tank 140 to collect the cleaning balls 142. The automatic cleaning system further includes an ejector 150 which communicates with a lower end of the cleaning ball storage tank 140 through a supply and recovery control pipe 147, so that, when the ejector 150 discharges a fluid supplied from a circulation pump 162, the pressure in the cleaning ball storage tank 140 is reduced, thereby recovering the cleaning balls 142 into the cleaning ball storage tank 140. The automatic cleaning system further includes a bypass pipeline 160 which has a fluid inlet guide pipe 161 and a fluid outlet guide pipe 163 such that the fluid flows from a fluid discharge pipe 126 via the ejector 150 and reenters the fluid discharge pipe 126. The automatic cleaning system further includes the circulation pump 162 which is mounted on the fluid inlet guide pipe 161 and supplies the fluid to the ejector 150 in one direction, thus realizing the supply and recovery of the cleaning balls 142. The automatic cleaning system further includes a motor-operated valve 164 which is mounted on the fluid outlet guide pipe 163 extending from an outlet of the ejector 150, so that the cleaning balls 142 are supplied or recovered by an ON/OFF operation of the motor-operated valve 164. The heat exchanger 120 has a shell and tube structure. The heat transfer tubes 122 are provided in the heat exchanger 120 so that fluid, supplied from a drive pump 112 provided on the inlet pipe 110, flows in the heat exchanger 120 and exchanges heat with air or another fluid in the heat exchanger 120. The ball separator 130 is coupled to the outlet pipe 124 of the heat exchanger 120 and serves to separate the cleaning balls 142 from fluid, which is discharged from the outlet pipe 124. The ball separator 130 has a hollow cylindrical shape. The separator plate 132 is provided and inclined in the ball separator 130 to separate the cleaning balls 142 from the fluid, which is discharged from the outlet pipe 124. As shown in FIG. 4, the separator plate 132 has an elliptical shape, a lower end of which extends in a rectangular shape. A plurality of slots 133 is formed through the separator plate 132 in the direction in which fluid flows. Furthermore, a direction change guide body 134 is provided on an edge of the separator plate 132 adjacent to the ball outlet 135 of the ball separator 130. The direction change guide body 134 guides a predetermined amount of fluid and the cleaning balls 142, which are discharged from the outlet pipe 124 of the heat exchanger 120, towards the ball outlet 135 provided on the lower end of the ball separator 130. The ball supplying pipe 137 and the ball recovery pipe 138 are respectively coupled to the inlet pipe 110 of the heat exchanger 120 and the ball outlet 135 of the ball separator 130 so as to supply the cleaning balls 142 from the cleaning ball storage tank 140 into the heat exchanger 120 and so as to recover the cleaning balls 142 from the ball separator 130 into the cleaning ball storage tank 140. Furthermore, check valves 137a and 138a are provided on the ball supplying pipe 137 and the ball recovery pipe 138 so as to prevent the backflow of the cleaning balls 421 when they are supplied from the cleaning ball storage tank 140 to the heat exchanger 120 or recovered from the ball separator 130 in the cleaning ball storage tank 140. The cleaning ball storage tank 140 communicates with both the ball supplying pipe 137 and the ball recovery pipe 138 in parallel. As shown in FIG. 5(a) and 5(b), the cleaning ball storage tank 140, having a hollow cylindrical shape, includes an outlet 145 which is provided at a predetermined position on an upper end of the tank and is coupled to the ball supplying pipe 137 and to the ball recovery pipe 138, and an inlet 144 which is provided on a lower end of the tank at a predetermined position facing the outlet 145 and communicates with the ejector 150 through the supply and recovery control pipe 147, such that flow resistance of up-flowing fluid to be discharged from the inlet 144 through the outlet 145 is reduced. The collection net 141 having a cylindrical shape is disposed in the cleaning ball storage tank 140 to collect the cleaning balls 142. Moreover, a side glass 143, which is made of glass or transparent plastic, is provided on an upper surface of the cleaning ball storage tank 140 to allow a user to observe the flow and state of wear of the cleaning balls 142. The ejector 150 communicates with the lower end of the cleaning ball storage tank 140 through the supply and recovery control pipe 147, which is coupled to the inlet 144 of the cleaning ball storage tank 140. Particularly, when it is desired to recover the cleaning balls 142 from the ball separator 130, the ejector 150 discharges fluid, supplied from the unidirectional circulation pump 162 provided on the fluid inlet guide pipe 161, at high speed, thus generating suction force. Then, the pressure in the supply and recovery control pipe 147 is reduced by the suction force so that fluid is drawn from the cleaning ball storage tank 140 into the ejector 150. As a result, the cleaning balls 142 are recovered from the ball separator 130 into the cleaning ball storage tank 140, which is reduced in pressure. As shown in FIG. 6, a nozzle 151 is provided in the ejector 150 to discharge fluid, supplied from the circulation pump 162, towards the fluid outlet guide pipe 163. The bypass pipeline 160 is coupled at first ends thereof to upper and lower ends of the ejector 150 and coupled at second ends thereof to the fluid discharge pipe 126, which extends from the outlet of the ball separator 130. Thus, the bypass pipeline 160 forms a fluid circulation structure such that, when the cleaning balls 142 are recovered, the fluid, which is drawn from the fluid discharge pipe 126 into the bypass pipeline 160 by the circulation pump 162, reenters the fluid discharge pipe 126 via the discharge process of the ejector 150. Here, a pipe of the bypass pipeline 160, which connects the fluid discharge pipe 126 to the upper end of the ejector 150, serves to supply fluid from the fluid discharge pipe 126 to the ejector 150 using the circulation pump 162. This pipe is called the fluid inlet guide pipe 161. A pipe of the bypass pipeline 160, which connects the fluid discharge pipe 126 to the lower end of the ejector 150, serves to resupply the fluid, discharged from the ejector 150, into the fluid discharge pipe 126. This pipe is called the fluid outlet guide pipe 163. The circulation pump 162, which circulates fluid in one direction and supplies the fluid from the fluid discharge pipe 126 to the ejector 150 during the supply and recovery of the cleaning balls 142, is mounted on the fluid inlet guide pipe 161. The motor-operated valve 164 is mounted on the fluid outlet guide pipe 163 and controls the fluid outlet guide pipe 163 such that the fluid discharge of the ejector 150 cause a pressure drop in the interior of the cleaning ball storage tank 140, thus recovering the cleaning balls 142. Therefore, the cleaning balls 142 are supplied to the heat exchanger 120 or recovered from the ball separator 130 in the cleaning ball storage tank 140 by an ON/OFF operation of the motor-operated valve 164, which is mounted on the pipe extending from the outlet of the ejector 150, that is, mounted on the fluid outlet guide pipe 163 coupled to the outlet of the ejector 150. In detail, while fluid is supplied to the ejector 150 by the operation of the circulation pump 162, if the motor- operated valve 164, which is mounted on the fluid outlet guide pipe 163 extending from the outlet of the ejector 150, is closed, the fluid discharged from the ejector 150 flows to the inlet pipe 110 of the heat exchanger 120 via the supply and recovery control pipe 147 and the cleaning ball storage tank 140. At this time, the cleaning balls 142, which have been in the cleaning ball storage tank 140, are moved into the inlet pipe 110 of the heat exchanger 120 along with the fluid flowing up through the cleaning ball storage tank 140. Subsequently, the cleaning balls 142 are supplied into the heat transfer tubes 122 of the heat exchanger 120 along with fluid which has entered the heat exchanger 120 through the inlet pipe 110 by the operation of the drive pump 112. The cleaning balls 142 conduct a cleaning process of removing scales from the inner surfaces of the heat transfer tubes 122. Conversely, if the motor-operated valve 164, which is mounted on the fluid outlet guide pipe 163 extending from the outlet of the ejector 150, is opened while the circulation pump 162 is operated, fluid is discharged from the ejector 150 to the fluid discharge pipe 126 through the fluid outlet guide pipe 163. That is, when the fluid is discharged by the nozzle 151 of the ejector 150 at high speed, suction force is generated in the ejector 150 by the pressure drop in the ejector 150. At this time, the cleaning balls 142 are separated from the fluid in the ball separator 130 and recovered from the ball separator 130 in the cleaning ball storage tank 140 by the suction force of the ejector 150. FIG. 7 is a view of an automatic heat exchanger cleaning system, according to a second embodiment of the present invention. FIG. 8 is a sectional view and a plan sectional view showing a cleaning ball storage tank of the automatic cleaning system of Fig. 7. The construction of this embodiment is as follows. The same reference numerals are used to designate components of the second embodiment that are the same as those of the first embodiment of the automatic cleaning system 100. In the automatic cleaning system 100a according to the second embodiment, unlike the automatic cleaning system 100 according to the first embodiment, a cleaning ball circulation process, in which, when a motor-operated valve 164 mounted on a ball supplying pipe 137 is opened, an ejector 150 discharges fluid at high speed so that cleaning balls 142, which have been in a cleaning ball storage tank 140, are supplied into a heat exchanger 120, thus cleaning the interior of heat transfer tubes 122 of the heat exchanger 120, is continuously executed for a predetermined time. Furthermore, when the motor-operated valve 164, which is mounted on the ball supplying pipe 137, is closed and a motor-operated valve 164a, which is mounted on a supply and recovery control pipe 147, is opened, the cleaning balls 142 are recovered from a ball separator 130 in the cleaning ball storage tank 140 by a pressure drop in the cleaning ball storage tank 140 due to the fluid discharge of the ejector 150. The construction of the automatic cleaning system 100a will be described herein below. As shown in FIG. 7, the automatic cleaning system

100a according to the second embodiment of the present invention includes the heat exchanger 120 which has an inlet pipe 110 at a first end thereof and an outlet pipe 124 at a second end thereof, with heat transfer tubes 122 provided in the heat exchanger 120. The automatic cleaning system 100a further includes the ball separator 130 which is coupled to the outlet pipe 124 of the heat exchanger 120 and has therein a separator plate 132 to separate the cleaning balls 142 from fluid discharged from the outlet pipe 124. The automatic cleaning system 100a further includes the ball supplying pipe 137 and a ball recovery pipe 138 which are respectively connected to an outlet 145 and an inlet 144 of the cleaning ball storage tank 140. The ball recovery pipe 138 is connected to a ball outlet of the ball separator 130, so that the cleaning balls circulate through the heat exchanger 120 or are recovered into the cleaning ball storage tank 140. The automatic cleaning system 100a further includes the cleaning ball storage tank 140 which communicates with both the ball supplying pipe 137 and the ball recovery pipe 138, with a collection net 141 provided in the cleaning ball storage tank 140 to collect the cleaning balls 142. The automatic cleaning system 100a further includes the supply and recovery control pipe 147 which is connected both to a lower end of the cleaning ball storage tank 140 and to the ball supplying pipe 137 such that, when the ejector 150 discharges fluid to recover the cleaning balls 142, fluid, which has been in the cleaning ball storage tank 140, is supplied to the ball supplying pipe 137. The automatic cleaning system 100a further includes the ejector 150 which is connected to the ball supplying pipe 137 and ejects fluid supplied from a circulation pump 162 to reduce pressure in the ball supplying pipe 137 or in the supply and recovery control pipe 147, thereby circulating the cleaning balls 142 through the heat exchanger 120 or recovering the cleaning balls 142 in the cleaning ball storage tank 140. The automatic cleaning system 100a further includes a bypass pipeline 160 which has a fluid inlet guide pipe 161 and a fluid outlet guide pipe 163 such that the fluid flows from the inlet pipe 110 via the ejector 150 and reenters the inlet pipe 110, and the circulation pump 162 which is mounted on the fluid inlet guide pipe 161 and supplies the fluid to the ejector 150 to circulate the fluid in one direction, thus realizing the supply and recovery of the cleaning balls 142. The automatic cleaning system 100a further includes the motor- operated valves 164 and 164a which are mounted on the ball supplying pipe 137 and the supply and recovery control pipe 147 so that the cleaning balls 142 are supplied or recovered according to the ON/OFF operation of the motor- operated valves 164 and 164a. Here, the heat exchanger 120, the ball separator 130 and the ejector 150 according to the second embodiment have the same construction as those of the heat exchanger 120, the ball separator 130 and the ejector 150 according the first embodiment, therefore further explanation of the heat exchanger 120, the ball separator 130 and the ejector 150 is deemed unnecessary. Only features unique to the second embodiment will be explained. In the second embodiment, the ball supplying pipe 137 and the ball recovery pipe 138 are respectively connected to the outlet 145 and the inlet 144 of the cleaning ball storage tank 140 while being respectively coupled to the inlet pipe 110 and the ball outlet 135 of the ball separator 130, such that the cleaning balls 142 continuously circulate from the cleaning ball storage tank 140 through the heat exchanger 120 and are recovered from the ball separator 130 into the cleaning ball storage tank 140. Meanwhile, the supply and recovery control pipe 147, which is coupled both to the lower end of the cleaning ball storage tank 140 and to the ball supplying pipe 137 in parallel, is used for recovering the cleaning balls 142. That is, fluid, which has been in the cleaning ball storage tank 140, is drawn into the ball supplying pipe 137 through the supply and recovery control pipe 147 by suction force of the ejector 150 generated when the ejector 150 discharges fluid while the motor-operated valve 164a is open. Then, the pressure in the cleaning ball storage tank 140 is reduced so that the cleaning balls 142 are recovered from the ball separator 130 in the cleaning ball storage tank 140. Furthermore, the motor-operated valves 164 and 164a are respectively mounted on the ball supplying pipe 137 and the supply and recovery control pipe 147 to selectively open or close the ball supplying pipe 137 and the supply and recovery control pipe 147, so that the suction force of the ejector 150, generated when discharging fluid at high speed, is selectively applied to the pipes, that is, to the ball supplying pipe 137 or the supply and recovery control pipe 147, thereby continuously circulating or recovering the cleaning balls 142. Moreover, a check valve 137a is provided on the ball supplying pipe 137 between the motor-operated valve 164 and the ejector 150 so as to prevent backflow of the cleaning balls 142 during circulation of the cleaning balls 142 from the cleaning ball storage tank 140 through the heat exchanger 120. The cleaning ball storage tank 140 communicates with both the ball supplying pipe 137 and the ball recovery pipe 138 in series. While the cleaning balls 142 continuously circulate, fluid is drawn into the cleaning ball storage tank 140 through an inlet 144, is turbulent in the cleaning ball storage tank 140, and is discharged through an outlet 145. As shown in FIG. 8, the cleaning ball storage tank 140 has a hollow cylindrical shape. To make the fluid passing from the inlet 144 to the outlet 145 turbulent, the inlet 144, which is coupled to the ball recovery pipe 138, is provided at a predetermined position on an upper end of the cleaning ball storage tank 140, and the outlet 145, which is coupled to the ball supplying pipe 137, is provided on the upper end of the tank at a position opposite the inlet 144 on the same horizontal line as the inlet 144. A fluid discharge hole 146 is formed at a central position in a lower end of the tank so as to discharge fluid from the cleaning ball storage tank 140 to the supply and recovery control pipe 147, thus recovering the cleaning balls 142. Furthermore, the collection net 141 having a cylindrical shape is disposed in the cleaning ball storage tank 140 to collect the cleaning balls 142. Moreover, a side glass 143, which is made of glass or transparent plastic, is provided on an upper surface of the cleaning ball storage tank 140 to allow a user to observe the flow and state of wear of the cleaning balls 142. The bypass pipeline 160 is coupled at first ends thereof to upper and lower ends of the ejector 150 and coupled at second ends thereof to the inlet pipe 110, which extends from the inlet of the heat exchanger 120. Thus, the bypass pipeline 160 forms a fluid circulation structure such that, when the cleaning balls 142 continuously circulate or are recovered, the fluid, which is drawn from the inlet pipe 110 into the bypass pipeline 160 by the circulation pump 162, reenters the inlet pipe 110 via the ejector 150. Here, a pipe of the bypass pipeline 160, which connects the inlet pipe 110 to the lower end of the ejector 150, serves to supply fluid from the inlet pipe 110 to the ejector 150 using the circulation pump 162. This pipe is called the fluid inlet guide pipe 161. A pipe of the bypass pipeline 160, which connects the upper end of the ejector 150 to the inlet pipe 110, serves to resupply the fluid, discharged from the ejector 150, to the inlet pipe 110. This pipe is called the fluid outlet guide pipe 163. Furthermore, the circulation pump 162, which supplies fluid from the inlet pipe 110 to the ejector 150 by rotating in one direction during the continuous circulation or recovery of the cleaning balls 142, is mounted on the fluid inlet guide pipe 161. The operation of the automatic cleaning system 100a according to the second embodiment of the present invention will be described herein below. In the drawings, the solid arrow ( -^" ) denotes a process of continuously circulating the cleaning balls 142. The dot-dashed arrow ( ) denotes a process of recovering the cleaning balls 142. First, in a process of continuously circulating the cleaning balls 142 to remove scales from inner surfaces of the heat transfer tubes 122 of the heat exchanger 120, of the motor-operated valves 164 and 164a, which are respectively mounted on the ball supplying pipe 137 and the supply and recovery control pipe 147 that are respectively connected to the outlet 145 of the cleaning ball storage tank 140 and to the fluid discharge hole 146 formed in the lower end of the cleaning ball storage tank 140, the motor- operated valve 164a, which is mounted on the supply and recovery control pipe 147, maintains its closed state. If only the motor-operated valve 164, which is mounted on the ball supplying pipe 137, is opened and the circulation pump 162, which is mounted on the fluid inlet guide pipe 161, is operated, some of the fluid, which has been supplied into the heat exchanger 120 through the inlet pipe 110, is drawn into the fluid inlet guide pipe 161, as shown in FIG. 7. Subsequently, the fluid is supplied into the ejector 150 by the circulation pump 162. The ejector 150 discharges the supplied fluid towards the fluid outlet guide pipe 163. The discharged fluid reenters the inlet pipe 110 adjacent to the inlet of the heat exchanger 120 through the fluid outlet guide pipe 163. Then, pressure in the ball supplying pipe 137 is reduced by the fluid discharge of the ejector 150, thereby generating the suction force of the ejector 150. As a result, the cleaning balls 142 and fluid, which have been in the cleaning ball storage tank 140, move into the ball supplying pipe 137 due to the suction force of the ejector 150. The cleaning balls 142 and fluid, which are supplied into the ball supplying pipe 137, are drawn into the inlet pipe 110, which extends from the inlet of the heat exchanger 120, through both the ejector 150, coupled to the ball supplying pipe 137, and the fluid outlet guide pipe 163, coupled to the upper end of the ejector 150. Thereafter, the cleaning balls 142 and fluid mix with the fluid, which has been supplied into the heat exchanger 120 by the drive pump 112 mounted on the inlet pipe 110, and are then supplied into the heat transfer tubes 122 of the heat exchanger 120. As a result, the cleaning balls 142 remove scales from the inner surfaces of the heat transfer tubes 122 while passing through the heat transfer tubes 122. The cleaning balls 142, having cleaned the heat transfer tubes 122, are discharged into the ball separator 130 coupled to the outlet pipe 124 of the heat exchanger 120. Subsequently, the cleaning balls 142 are separated from the fluid by the separator plate 132 in the ball separator 130. The process of separating the cleaning balls 142 from the fluid in the ball separator 130 will be explained in detail herein below. The suction force generated in the ejector 150 is applied to the ball outlet 135 of the ball separator 130 via the cleaning ball storage tank 140. Then, the cleaning balls 142, which have been in the ball separator 130, are guided to the ball outlet 135, formed in the lower end of the ball separator 130, by a direction change guide body 134 provided on a lower edge of the separator plate 132. The cleaning balls 142, guided to the ball outlet 135, sequentially pass through the ball recovery pipe 138, the cleaning ball storage tank 140 and the ball supplying pipe 137 using the suction force of the ejector 150 and move again into the heat exchanger 120. As such, the cleaning balls 142 continuously circulate through the above- mentioned path for a desired time, thus cleaning the inner surface of the heat transfer tubes 122 installed in the heat exchanger 120. The process of recovering the cleaning balls 142, having been separated from the fluid in the ball separator 130, into the cleaning ball storage tank 140 is as follows. While the circulation pump 162 maintains its driving state, the motor-operated valve 164a mounted on the supply and recovery control pipe 147 is opened and the motor-operated valve 164 mounted on the ball supplying pipe 137 is closed. Then, as shown in FIG. 7, the pressure in the supply and recovery control pipe 147 is reduced by the fluid discharge operation of the ejector 150, thus generating suction force. Thereby, fluid, which has been in the cleaning ball storage tank 147, is supplied into the supply and recovery control pipe 147. As a result, the cleaning balls 142, having been separated from the fluid by the separator plate 132 in the ball separator 130, are recovered, along with some fluid, by the suction force applied to the cleaning ball storage tank 140 into the collection net 141 disposed in the cleaning ball storage tank 140 after passing through the ball recovery pipe 138 which connects the ball outlet 135, formed in the lower end of the ball separator 130, to the inlet 144 of the cleaning ball storage tank 140. FIG. 9 is a view of an automatic heat exchanger cleaning system, according to a third embodiment of the present invention. The construction of the third embodiment will be explained herein below. The same reference numerals are used to designate components of the third embodiment that are the same as those of the first embodiment of the automatic cleaning system 100. As shown in FIG. 9, the automatic cleaning system

100b according to the third embodiment includes one or more heat exchangers 120a, 120b and 120c, each of which has an inlet pipe 124 at a first end thereof and an outlet pipe 124 at a second end thereof. A plurality of heat transfer tubes 122 is provided in each heat exchanger 120a, 120b, 120c. The automatic cleaning system 100b further includes a ball separator 130 which is coupled to the outlet pipes 124 of the heat exchangers 120a, 120b and 120c and has therein a separator plate 132 to separate cleaning balls 142 from fluid discharged from the outlet pipes 124. The automatic cleaning system 100b further includes a ball supplying pipe 137 and a ball recovery pipe 138 which are respectively connected to an outlet 145 and an inlet 144 of a cleaning ball storage tank 140 such that the ball recovery pipe 138 is connected to a ball outlet 135 of the ball separator 130, thus circulating the cleaning balls 142 through the heat exchangers 120a, 120b and 120c or recovering the cleaning balls 142 into the cleaning ball storage tank 140. The automatic cleaning system 100b further includes the cleaning ball storage tank 140, which communicates both with the ball supplying pipe 137 and with the ball recovery pipe 138. A collection net 141 is provided in the cleaning ball storage tank 140 to collect the cleaning balls 142. The automatic cleaning system 100b further includes a supply and recovery control pipe 147 which is connected both to a lower end of the cleaning ball storage tank 140 and to the ball supplying pipe 137 such that, when ejectors 150a, 150b and 150c discharge fluid to recover the cleaning balls 142, fluid, which has been in the cleaning ball storage tank 140, is supplied to the ball supplying pipe 137. The automatic cleaning system 100b further includes one or more ejectors 150a, 150b and 150c which are connected to the ball supplying pipe 137 and discharge fluid supplied from a circulation pump 162 to reduce pressure in the ball supplying pipe 137 or in the supply and recovery control pipe 147, thereby circulating the cleaning balls 142 through the heat exchanger 120 or recovering the cleaning balls 142 in the cleaning ball storage tank 140. The automatic cleaning system 100b further includes a multi-type bypass pipeline 160 which has one or more fluid inlet guide pipes 161a, 161b and 161c and fluid outlet guide pipes 163a, 163b and 163c such that fluid flows from the inlet pipes 110 via the ejectors 150a, 150b and 150c and reenters the inlet pipes 110 coupled to respective ejectors 150a, 150b and 150c. The automatic cleaning system 100b further includes the circulation pump 162 which is mounted on the fluid inlet guide pipe 161c and supplies fluid to the ejectors 150a, 150b and 150c in one direction, thus realizing the supply and recovery of the cleaning balls 142. The automatic cleaning system 100b further includes motor-operated valves 164, 164a, 165a, 165b and 165c which are respectively mounted on the ball supplying pipe 137, the supply and recovery control pipe 147 and the fluid inlet guide pipes 161a, 161b and 161c, which connect the ejectors 150a, 150b and 105c to the circulation pump 162, so that the cleaning balls 142 are supplied or recovered according to the ON/OFF operation of the motor-operated valves, and fluid is selectively supplied to the ejectors 150a, 105b and 150c according to the ON/OFF operation of the motor-operated valves. The automatic cleaning system 100b of the third embodiment having the above-mentioned construction is the multi-type cleaning system, as shown FIG. 9. To clean the heat transfer tubes 122 installed in one or more heat exchangers, that is, three heat exchangers 120a, 120b and 120c, the ejectors 150a, 150b and 150c, which are coupled to the ball supplying pipe 137 such that the ejectors 150a, 150b and 150c correspond to three heat exchangers 120a, 120b and 120c, and respectively communicate with the fluid inlet guide pipes 161a, 161b and 161c and with the fluid outlet guide pipes 163a, 163b and 163c, discharge fluid. Then, the cleaning balls 142, which have been in the cleaning ball storage tank 140, are supplied into and circulate through the heat exchangers 120a, 120b and 120c, thus cleaning the heat transfer tubes 122 of the heat exchangers 120a, 120b and 120c. Furthermore, the cleaning balls 142, which are discharged from the heat exchangers 120a, 120b and 120c, enter the ball separator 130 and are recovered in the cleaning ball storage tank 140. As such, the automatic cleaning system according to the third embodiment can be constructed in a place in which one or more heat exchangers 120a, 120b and 120c are installed. Here, each heat exchanger 120a, 120b, 120c, the ball separator 130 and each ejector 150a, 150b, 150c according to the third embodiment have the same construction as do the heat exchanger 120, the ball separator 130 and the ejector 150 according to the first embodiment. As well, the cleaning ball storage tank 140 of the third embodiment has the same construction as does the cleaning ball storage tank 140 of the second embodiment. Therefore, further explanation of the heat exchangers 120a, 120b and 120c, the ball separator 130, the ejectors 150a, 150b and 150c and the cleaning ball storage tank 140 is deemed unnecessary. Only construction unique to the third embodiment will be explained. In the third embodiment, the inlet pipes 110 and the ball supplying pipes 137 comprise branch pipes 110a, 100b and 110c and 136a, 136b and 136c which communicate with one or more ejectors 150a, 150b and 150c in a multiple arrangement. Furthermore, the outlet pipes 124, coupled to the ball separator 130, comprise branch pipes 124a, 124b and 124c. Ends of the branch pipes 124a, 124b and 124c form one pipeline that communicates with the inlet of the ball separator 130. Meanwhile, check valves 137b, 137c and 137d are provided on respective branch pipes 136a, 136b and 136c of the ball supplying pipe 137 which connects the motor- operated valve 164 to the ejectors 150a, 150b and 150c, thus preventing backflow of the cleaning balls 142 during the circulation of the cleaning balls 142 from the cleaning ball storage tank 140 through the heat exchanger 120. The motor-operated valves 165a, 165b and 165c are mounted on the fluid inlet guide pipes 161a, 161b and 161c, which connect the ejectors 150a, 150b 50c to an outlet of the circulation pump 162, so as to allow a user to selectively control the fluid inlet guide pipes 161a, 161b and 161c according to a desired purpose. Therefore, as required, only one or two heat exchangers 120a, 120b, 120c may be cleaned by selectively controlling the motor- operated valves 165a, 165b and 165c. The automatic cleaning system 100b of the third embodiment of the present invention having the above- mentioned construction is operated in the same manner as that of the automatic cleaning system 100a of the second embodiment. In a process of continuously circulating the cleaning balls 142, the cleaning balls 142 are drawn from the cleaning ball storage tank 140 into the ball supplying pipe 137 by suction force generated by fluid discharge of one or more ejectors 150a, 150b and 150c, that is, three ejectors 150a, 150b and 150c which are coupled to three heat exchangers 120a, 120b and 120c through the fluid outlet guide pipes 163a, 163b and 163c. The cleaning balls 142, which are drawn into the ball supplying pipe 137, are supplied into the ejectors 150a, 150b and 150c through the branch pipes 137a, 137b and 137c of the ball supplying pipe 137 which are coupled to respective ejectors 150a, 150b and 150c. Subsequently, the cleaning balls 142 are supplied to the inlet pipes 110a, 110b and 110c, which extend from the inlet of the heat exchangers 120a, 120b and 120c, through the fluid outlet guide pipes 163a, 163b and 163c which connect the ejectors 150a, 150b and 150c to the heat exchangers 120a, 120b and 120c. Thereafter, the cleaning balls 142 mix with fluid which is supplied into the heat exchangers 120a, 120b and 120c by the drive pump 112 mounted on the inlet pipe 110, and the cleaning balls 142 and the fluid are then supplied into the heat transfer tubes 122 of the heat exchangers 120a, 120b and 120c. As a result, the cleaning balls 142 remove scales from the inner surfaces of the heat transfer tubes 122 while passing through the heat transfer tubes 122. The cleaning balls 142, which passed through the heat transfer tubes 122, are repeatedly moved by the suction force of the ejectors 150a, 150b and 150c from the ball outlet 135 of the ball separator 130 to the inlet pipes 110a, 110b and 110c of the heat exchangers 120a, 120b and 120c via the ball recovery pipe 138, the cleaning ball storage tank 140 and the ball supplying pipe 137. As such, the cleaning balls 142 clean the inner surface of the heat transfer tubes 122, which are installed in the heat exchangers 120a, 120b and 120c, while continuously circulating through the above-mentioned path for a predetermined time. Meanwhile, the process of recovering the cleaning balls 142 is the same as the process of recovering the cleaning balls 142 in the automatic cleaning system 100a of the second embodiment, therefore further explanation is deemed unnecessary. If it is desired to clean only one heat exchanger

120a among the three heat exchangers 120a, 120b and 120c, fluid is supplied to the fluid inlet guide pipe 161a from the inlet pipe 110 by the circulation pump 162 and is supplied only to the ejector 150a that is coupled to the heat exchanger 120a that must be cleaned, through the fluid outlet guide pipe 163a. Thereafter, the cleaning balls 142 are drawn into the ball supplying pipe 137 by fluid discharge of the ejector 150a, and are then supplied into the desired heat exchanger 120a, thus cleaning the heat transfer tubes 122 of the heat exchanger 120a. For an additional explanation about this, the three heat exchangers 120a, 120b and 120c, the three ejectors 150a, 150b and 150c, the three fluid inlet guide pipe 161a, 161b and 161c and the three motor-operated valves 165a, 165b and 165c are designated by the reference characters A, B and C. First, to clean the heat transfer tubes 122 of only the heat exchanger A 120a, the motor-operated valves B and C 165b and 165c, which are respectively mounted on the fluid inlet guide pipes B and C 161b and 161c which connect the ejectors B and C 150b and 150c to the inlet pipe 110, are closed, while the motor-operated valve A 165a, which is mounted on the fluid inlet guide pipe A 161a which connects the ejector A 150a to the inlet pipe 110, is opened. Then, fluid, which is drawn into the inlet pipe 110 by the circulation pump 162, is supplied into the ejector A 150a through the opened fluid inlet guide pipe A 161a. As a result, the cleaning balls 142, which are drawn into the ball supplying pipe 137 by the fluid discharge of the ejector A 150a, are then supplied into the heat exchanger A 120a, thus cleaning the heat transfer tubes 122 of the heat exchanger A 120a. To clean the heat transfer tubes 122 of only the heat exchanger B 120b, in the same method as described above, the motor-operated valve B 165b, mounted on the fluid inlet guide pipe B 161b corresponding to the heat exchanger B 120b, is opened, while the remaining motor-operated valves A and C 165a and 165c are closed. Then, fluid, which is drawn into the inlet pipe 110 by the circulation pump 162, is supplied into the ejector B 150b through the opened fluid inlet guide pipe B 161b. As a result, the cleaning balls 142 are supplied into the heat exchanger B 120b by the fluid discharge of the ejector B 150b, thus cleaning the heat transfer tubes 122 of the heat exchanger B 120b. To clean the heat transfer tubes 122 of only the heat exchanger C 120c, in the same method as described above, the only motor-operated valve C 165c corresponding to the heat exchanger C 120c is opened, while the remaining motor- operated valves A and B 165a and 165b are closed, such that fluid is supplied only into the ejector C 150c through the fluid inlet guide pipe C 161c by the circulation pump 162. Hereinafter, the operation of the automatic cleaning system of the present invention will be explained in detail . FIG. 10 is a view showing the operation of the automatic cleaning system according to the first embodiment of the present invention. In the drawings, the solid arrow ( ) denotes a process of supplying the cleaning balls 142. The dot-dashed arrow ( "^~ ) denotes a process of recovering the cleaning balls 142. In the preparation state of the system (when the system is not operated) , fluid is supplied into the heat exchanger 120 by the drive pump 112, and the cleaning balls 142 are in the collection net 141 of the cleaning ball storage tank 140. As well, the circulation pump 162, which is mounted on the fluid inlet guide pipe 161 of the bypass pipeline 160 connecting the ejector 150 to the fluid discharge pipe 126, is in a closed state. In addition, the motor-operated valve 164, which is mounted on the fluid outlet guide pipe 163 of the bypass pipeline 160, is in a closed state. In such a preparation state, the process of supplying the cleaning balls 142 for removing scales from the inner surfaces of the heat transfer tubes 122 of the heat exchanger 120 will be explained herein below. In the process of supplying the cleaning balls 142 for removing scales from the inner surfaces of the heat transfer tubes 122 of the heat exchanger 120, while the motor-operated valve 164, which is mounted on the fluid outlet guide pipe 163 of the bypass pipeline 160, is closed so that the circulation path of, the bypass pipeline 160 is closed, the circulation pump 162, which is mounted on the fluid inlet guide pipe 161, is operated. Then, as shown in FIG. 10, some fluid is discharged from the ball separator 130 towards the fluid discharge pipe 126 by the suction action of the circulation pump 162 and is then drawn into the ejector 150 through the fluid inlet guide pipe 161. Thereafter, the fluid, drawn into the ejector 150, flows into the cleaning ball storage tank 140, which contains therein the cleaning balls 142, through the supply and recovery control pipe 147, which connects the ejector 150 to the inlet 144 formed at a predetermined position on the lower end of the cleaning ball storage tank 140. The fluid, which is drawn into the cleaning ball storage tank 140, is discharged into the ball supplying pipe 137 through the outlet 145, which is formed on the upper end of the cleaning ball storage tank 140 at a position facing the inlet 144. At this time, the cleaning balls 142, which have been in the cleaning ball storage tank 140, are simultaneously discharged into the ball supplying pipe 137 along with the fluid which is discharged through the outlet 145. Subsequently, the cleaning balls 142 move into the inlet pipe 110 of the heat exchanger 120 with the flow of the fluid discharged to the ball supplying pipe 137. The cleaning balls 142, which are drawn into the inlet pipe 110 of the heat exchanger 120, mix with fluid, which is supplied into the heat exchanger 120 by the drive pump 112 mounted on the inlet pipe 110, and are then supplied into the heat transfer tubes 122 of the heat exchanger 120, thus removing scales from the inner surfaces of the heat transfer tubes 122 while passing through the heat transfer tubes 122. Thereafter, the cleaning balls 142, having passed through the heat transfer tubes 122, are discharged into the ball separator 130 coupled to the outlet pipe 124 of the heat exchanger 120 and are separated from the fluid by the separator plate 132 in the ball separator 130. To recover the cleaning balls 142, which are separated from the fluid in the ball separator 130, into the cleaning ball storage tank 140, the motor-operated valve 164, which is mounted on the fluid outlet guide pipe 163 of the bypass pipeline 160, is opened while the circulation pump 162 maintains its driving state. Then, as shown in FIG. 10, some fluid, which is discharged from the ball separator 130 into the fluid discharge pipe 126 by the suction of the circulation pump 162, is drawn into the ejector 150 through the fluid inlet guide pipe 161. The fluid, which is drawn into the ejector 150, is discharged to the fluid outlet guide pipe 163 through the opened motor-operated valve 164 by the fluid discharge action of the ejector 150. At this time, the pressure in the supply and recovery control pipe 147, which is coupled to the inlet 144 of the cleaning ball storage tank 140, is reduced by the fluid discharge action of the ejector 150, thus generating suction force. The fluid, which has been in the cleaning ball storage tank 140, is discharged to the fluid outlet guide pipe 163 through the supply and recovery control pipe 147 by the generated suction force. Then, the cleaning balls 142, which have been in the ball separator 130, are moved to the ball outlet 135 of the ball separator 130 under the guide of the direction change guide body 134 by the suction force applied to the cleaning ball storage tank 140. Subsequently, the cleaning balls 142, which are guided to the ball outlet 135, are recovered in the collection net 141 of the cleaning ball storage tank 140 through the ball recovery pipe 138, which connects the ball outlet 135 of the ball separator 130 to the outlet 145 of the cleaning ball storage tank 140. Furthermore, the fluid, which is discharged to the fluid outlet guide pipe 163 by the fluid discharge of the ejector 150, flows into the fluid discharge pipe 126 coupled to the fluid outlet guide pipe 163 and then mixes with the fluid which is discharged from the ball separator 130 to the fluid discharge pipe 126. The mixed fluid flows into another device (not shown) which is on a subsequent fluid flow path. Although the preferred embodiments of the present invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.

[industrial Applicability] As described above, the present invention provides an automatic cleaning system which supplies cleaning balls to heat exchangers using the combination of a pump and an ejector, thus removing contaminants stuck to inner surfaces of heat transfer tubes in the heat exchanger. In detail, the present invention provides an automatic heat exchanger cleaning system which supplies fluid to a cleaning ball storage tank, containing cleaning balls therein, using a unidirectional circulation pump so that the cleaning balls are supplied into heat transfer tubes of a heat exchanger by the supplied fluid, and the cleaning balls pass through the heat transfer tubes along with the fluid, thus removing scales from the heat transfer tubes. Furthermore, the present invention has a structure such that, when it is desired to recover the cleaning balls, a motor-operated valve, provided at an end of the ejector, is opened to supply fluid from the circulation pump to the ejector, and the ejector discharges the fluid using a nozzle provided in the ejector, thus reducing the pressure in the cleaning ball storage tank, thereby recovering the cleaning balls into the cleaning ball storage tank. Therefore, in the present invention, the time required to supply and recover the cleaning balls can be arbitrarily adjusted according to the conditions at a system installation site, thus easily executing the supply and recovery of the cleaning balls . Furthermore, the present invention solves the problem of the cleaning balls supplied into a ball separator becoming temporarily jammed in the conventional arts, thus preventing pressure from being lost and the cleaning balls from wearing due to the temporary cleaning ball jamming phenomenon. Moreover, the present invention markedly reduces the probability of malfunction and installation costs of the circulation pump, compared to the conventional arts in which the rotation direction of a circulation pump must periodically changed between normal and reverse directions to supply and recover cleaning balls .

Claims

[CLAIMS] [Claim l] An automatic heat exchanger cleaning system, comprising: a heat exchanger having an inlet pipe at a first end thereof and an outlet pipe at a second end thereof, with a plurality of heat transfer tubes provided in the heat exchanger; a ball separator coupled to the outlet pipe of the heat exchanger and having therein a separator plate to separate cleaning balls from fluid discharged from the outlet pipe; a ball supplying pipe and a ball recovery pipe respectively coupled to the inlet pipe of the heat exchanger and a ball outlet of the ball separator so as to supply and recover the cleaning balls into the heat exchanger and a cleaning ball storage tank; the cleaning ball storage tank communicating with both the ball supplying pipe and the ball recovery pipe in parallel, with a collection net provided in the cleaning ball storage tank to collect the cleaning balls; an ejector communicating with a lower end of the cleaning ball storage tank through a supply and recovery control pipe, so that, when the ejector discharges a fluid supplied from a circulation pump, pressure of the cleaning ball storage tank is reduced, thereby the cleaning balls are recovered into the cleaning ball storage tank; a bypass pipeline having a fluid inlet guide pipe and a fluid outlet guide pipe such that the fluid flows from a fluid discharge pipe via the ejector and reenters the fluid discharge pipe; the circulation pump mounted on the fluid inlet guide pipe and supplying the fluid to the ejector in one direction, thus realizing the supply and recovery of the cleaning balls; and a motor-operated valve mounted on the fluid outlet guide pipe extending from an outlet of the ejector so that the cleaning balls are supplied or recovered by an ON/OFF operation of the motor-operated valve.

[Claim 2] An automatic heat exchanger cleaning system, comprising: a heat exchanger having an inlet pipe at a first end thereof and an outlet pipe at a second end thereof, with a plurality of heat transfer tubes provided in the heat exchanger; a ball separator coupled to the outlet pipe of the heat exchanger and having therein a separator plate to separate cleaning balls from fluid discharged from the outlet pipe; a ball supplying pipe and a ball recovery pipe respectively connected to an outlet and an inlet of a cleaning ball storage tank, the ball recovery pipe being connected to a ball outlet of the ball separator, so that the cleaning balls circulate through the heat exchanger or are recovered into the cleaning ball storage tank; the cleaning ball storage tank communicating with both the ball supplying pipe and the ball recovery pipe, with a collection net provided in the cleaning ball storage tank to collect the cleaning balls; a supply and recovery control pipe connected both to a lower end of the cleaning ball storage tank and to the ball supplying pipe such that, when an ejector discharges fluid to recover the cleaning balls, fluid, which has been in the cleaning ball storage tank, is supplied to the ball supplying pipe; the ejector connected to the ball supplying pipe and ejecting fluid supplied from a circulation pump to reduce pressure in the ball supplying pipe or in the supply and recovery control pipe, thereby circulating the cleaning balls through the heat exchanger or recovering .the cleaning balls in the cleaning ball storage tank; a bypass pipeline having a fluid inlet guide pipe and a fluid outlet guide pipe such that the fluid flows from the inlet pipe via the ejector and reenters the inlet pipe; the circulation pump mounted on the fluid inlet guide pipe and supplying the fluid to the ejector in one direction, thus realizing the supply and recovery of the cleaning balls; and motor-operated valves mounted on the ball supplying pipe and the supply and recovery control pipe so that the cleaning balls are supplied or recovered according to ON/OFF operation of the motor-operated valves .

[Claim 3] An automatic heat exchanger cleaning system, comprising: one or more heat exchangers each having an inlet pipe at a first end thereof and an outlet pipe at a second end thereof, with a plurality of heat transfer tubes provided in each of the heat exchangers; a ball separator coupled to the outlet pipes of the heat exchangers and having therein a separator plate to separate cleaning balls from fluid discharged from the outlet pipes; a ball supplying pipe and a ball recovery pipe respectively connected to an outlet and an inlet of a cleaning ball storage tank, the ball recovery pipe being connected to a ball outlet of the ball separator, so that the cleaning balls circulate through the heat exchangers or are recovered into the cleaning ball storage tank; the cleaning ball storage tank communicating with both the ball supplying pipe and the ball recovery pipe, with a collection net provided in the cleaning ball storage tank to collect the cleaning balls; a supply and recovery control pipe connected both to a lower end of the cleaning ball storage tank and to the ball supplying pipe such that, when ejectors eject fluid to recover the cleaning balls, fluid, -which has been in the cleaning ball storage tank, is supplied to the ball supplying pipe; one or more ejectors connected to the ball supplying pipe and discharging fluid supplied from a circulation pump to reduce pressure in the ball supplying pipe or in the supply and recovery control pipe, thereby circulating the cleaning balls through the heat exchangers or recovering the cleaning balls in the cleaning ball storage tank; a multi-type bypass pipeline having one or more fluid inlet guide pipes and fluid outlet guide pipes such that fluid flows from the inlet pipes via the ejectors and reenters the inlet pipes coupled to the ejectors; the circulation pump mounted on the fluid inlet guide pipe and supplying the fluid to the ejectors in one direction, thus realizing the supply and recovery of the cleaning balls; and motor-operated valves mounted on the ball supplying pipe, the supply and recovery control pipe and the fluid inlet guide pipes, which connect the ejectors to the circulation pump, so that the cleaning balls are supplied or recovered according to ON/OFF operation of the motor- operated valves, and fluid is selectively supplied to the ejectors according to ON/OFF operation of the motor- operated valves .

[Claim 4] The automatic heat exchanger cleaning system according to claim 1, wherein the cleaning ball storage tank has a hollow cylindrical shape and comprises: an outlet provided at a predetermined position on an upper end of the tank and coupled to the ball supplying pipe and the ball recovery pipe; and an inlet provided on a lower end of the tank at a predetermined position facing the outlet and communicating with the ejector through the supply and recovery control pipe, so that flow resistance of up- flowing fluid to be discharged from the inlet through the outlet is reduced.

[Claim 5] The automatic heat exchanger cleaning system according to claim 4, further comprising: check valves provided on the ball supplying pipe and the ball recovery pipe so as to prevent backflow of the cleaning balls during the cleaning ball supplying or recovering process.

[Claim 6] The automatic heat exchanger cleaning system according to claim 2 or 3, wherein the cleaning ball storage tank is constructed such that fluid drawn into the cleaning ball storage tank through the inlet becomes turbulent and is discharged along with the cleaning balls through the outlet, thus supplying the cleaning balls.

[Claim 7] The automatic heat exchanger cleaning system according to claim 2 or 3, wherein the cleaning ball storage tank has a hollow cylindrical shape and comprises : the inlet provided at a predetermined position on an upper end of the tank and coupled to the ball recovery pipe; the outlet provided on the upper end of the tank at a position opposite the inlet on the same horizontal line as the inlet and coupled to the ball supplying pipe, such that fluid to be discharged from the inlet through the outlet becomes turbulent; and a fluid discharge hole formed at a central position in a lower end of the tank so as to discharge fluid from the cleaning ball storage tank to the supply and recovery control pipe, thus recovering the cleaning balls.

[Claim 8] The automatic heat exchanger cleaning system according to any one of claims 1 through 3, wherein the separator plate has an elliptical shape, a lower end of which extends in a rectangular shape, is disposed and inclined in the ball separator, and comprises a slot formed through the separator plate in the direction in which fluid flows .

[Claim 9] The automatic heat exchanger cleaning system according to any one of claims 1 through 3, further comprising: a direction change guide body provided on an edge of the separator plate adjacent to the ball outlet of the ball separator so as to guide the cleaning balls to be discharged to the ball outlet .

[Claim 10] The automatic heat exchanger cleaning system according to any one of claims 1 through 3, wherein the ejector comprises therein a nozzle to discharge fluid supplied from the circulation pump.

[Claim ll] The automatic heat exchanger cleaning system according to any one of claims 1 through 3, wherein the cleaning ball storage tank comprises a side glass on an upper surface thereof to allow a user to observe a flow and a rate of wear of the cleaning balls .

[Claim 12] The automatic heat exchanger cleaning system according to claim 3, wherein the inlet pipes and the ball supplying pipes form a branching pipe structure communicating with one or more ejectors in a multiple arrangement, and the outlet pipes, coupled to the ball separator, form a branching pipe structure.

[Claim 13] The automatic heat exchanger cleaning system according to claim 3, wherein the motor-operated valves are mounted on the fluid inlet guide pipes, which connect the ejectors to an outlet of the circulation pump, so as to allow a user to control the fluid inlet guide pipes according to a purpose.