COOLING-WATER CIRCULATION SYSTEM

TECHNICAL FIELD

The present invention relates to a cooling-water circulation system, and more particularly to a cooling-water circulation system including a cooling-tower-side circulation path and a chiller-machine-side circulation path.

BACKGROUND ART

There is generally known a conventional cooling-water circulation system including a cooling-tower-side circulation path (also referred to as a generally “primary circulation path”) for circulating cooling water between a cooling tower and a chiller machine, and a chiller-machine-side circulation path (also referred to as a “secondary circulation path”) for circulating cooling water between the chiller machine and a cooling target part (e.g., refer to Patent Literature 1).

In the conventional cooling-water circulation system, the cooling-tower-side circulation path and the chiller-machine-side circulation path are independent, and cooling water separately circulates in each circulation path. Then, manufacturers usually manage maintenance by administering preservatives, disinfectants, and the like to mainly the cooling-tower-side circulation path while hardly administering them to a temperature regulator, a mold cooling hole, another cooling device, and the like, which are connected to a tank of the chiller machine. As a result, corrosion (rust) of cooling pipes and the like directly connected to a product, and hard scales including silica, and the like, adhering to the inside of pipes, cause insufficient cooling. This may cause various obstacles such as variations in product quality, reduction in productivity, increase of equipment cost, and the like.

For this reason, as illustrated in FIG. 8, there is proposed a cooling water replacing apparatus 100 for replacing cooling water in a tank 106a of a chiller machine 106, for example. The cooling water replacing apparatus 100 is configured such that a drain tank 104 is installed near the chiller machine 106 and the tank 106a of the chiller machine 106 and the drain tank 104 is connected by a pipe 105 provided with a drain valve 105a, and such that a drain pipe 107 provided with a conveying pump 107a is connected at one end into the drain tank 104. Then, at the timing of discharging cooling water, the drain valve 105a is manually opened to drain the cooling water, and then the drain valve 105a is closed manually.

CITATIONS LIST
Patent Literatures

Patent Literature 1: Japanese Unexamined Patent Application Publication No. 2005-21979

SUMMARY OF INVENTION
Technical Problems

Unfortunately, the above conventional cooling water replacing apparatus 100 is configured to manually drain the cooling water in the tank 106a of the chiller 106, so that the draining work may be forgotten at any moment. In addition, water is drained at a long interval, so that cooling water in the tank of the chiller machine is deteriorated in water quality to cause the inside of the tank to be a rusty mud state. As a result, when water is drained, solid matters of rust and scales adhere to or enter an operating portion of a float valve, for example, to cause clogging troubles. This may result in malfunctioning to cause the cooling water overflows from the inside of the tank. Further, drainage equipment such as a drain tank needs to be installed near the chiller machine to result in a complicated structure.

The present invention is made in light of the above-described circumstances, and an object thereof is to provide a cooling-water circulation system having a simple structure that allows easy drainage of cooling water in a chiller-machine-side circulation path.

Solutions To Problems

In order to solve the above problem, the invention as defined in claim 1 relates to a cooling-water circulation system comprising: a cooling-tower-side circulation path for circulating cooling water between a cooling tower and a chiller machine; and a chiller-machine-side circulation path for circulating cooling water between the chiller machine and a cooling target part, wherein the cooling-tower-side circulation path and the chiller-machine-side circulation path are connected by a first connecting pipe for introducing cooling water circulating through the chiller-machine-side circulation path into the cooling-tower-side circulation path.

The invention as defined in claim 2 relates to the cooling-water circulation system according to claim 1, wherein the first connection pipe is provided at its one end with a differential pressure injector disposed in a pipe constituting the cooling-tower-side circulation path, and the differential pressure injector is able to introduce cooling water flowing through the first connection pipe to cooling water flowing through the pipe, under a lower pressure than the cooling water flowing through the pipe.

The invention as defined in claim 3 relates to the cooling-water circulation system according to claim 2, wherein the differential pressure injector includes a small-diameter nozzle that is connected to one end of the first connection pipe and that is disposed such that its axis is along a flow direction of cooling water in the pipe, a large-diameter nozzle that is disposed such that its axis aligns with the axis of the small-diameter nozzle, and such that its discharge port is positioned downstream of a discharge port of the small-diameter nozzle in the flow direction of the cooling water in the pipe, and an intake port for taking the cooling water flowing through the pipe into the large-diameter nozzle to generate negative pressure in front of the discharge port of the small-diameter nozzle.

The invention as defined in claim 4 relates to the cooling-water circulation system according to claim 3, wherein the large-diameter nozzle is disposed so as to cover an outer peripheral surface of the small-diameter nozzle, and the intake port is formed in a portion of the large-diameter nozzle, covering the outer peripheral surface of the small-diameter nozzle.

The invention as defined in claim 5 relates to the cooling-water circulation system according to claim 4, wherein a plurality of the intake ports is formed along a circumferential direction around the axis of the large-diameter nozzle, and each of the intake ports is formed in an elliptical shape having a minor axis along the circumferential direction around the axis of the large-diameter nozzle.

The invention as defined in claim 6 relates to the cooling-water circulation system according to any one of claims 1 to 5, wherein the chiller-machine-side circulation path is provided in its feed path with a water impurity separation device for removing impurities contained in cooling water circulating the chiller-machine-side circulation path, the water impurity separation device includes a drain port for draining the cooling water together with separated impurities, and the first connection pipe connects the drain port and a return path of the cooling-tower-side circulation path.

The invention as defined in claim 7 relates to the cooling-water circulation system according to any one of claims 1 to 6, wherein the first connection pipe is provided with an electric valve that opens and closes the first connection pipe by opening and closing control of a control unit.

The invention as defined in claim 8 relates to the cooling-water circulation system according to any one of claims 1 to 7, wherein the first connection pipe is provided with a constant flow valve of a washer rubber type.

The invention as defined in claim 9 relates to the cooling-water circulation system according to any one of claims 1 to 8, wherein the cooling-tower-side circulation path and the chiller-machine-side circulation path are connected by a second connection pipe for introducing cooling water circulating through the cooling-tower-side circulation path into the chiller-machine-side circulation path.

The invention as defined in claim 10 relates to the cooling-water circulation system according to claim 9, wherein the second connection pipe connects a feed path of the cooling-tower-side circulation path and a tank provided in the chiller machine.

The invention as defined in claim 11 relates to the cooling-water circulation system according to claim 10, wherein the second connection pipe is provided at its one end with a float valve for opening and closing the second connection pipe in accordance with vertical movement of a water surface in the tank.

Advantageous Effects of Invention

The cooling-water circulation system of the present invention is configured such that the cooling-tower-side circulation path and the chiller-machine-side circulation path are connected by a first connection pipe for introducing cooling water circulating through the chiller-machine-side circulation path into the cooling-tower-side circulation path. This causes the cooling water circulating through the chiller-machine-side circulation path to be introduced into the cooling-tower-side circulation path via the first connection pipe. Then, manufacturers usually manage maintenance by administering preservatives, disinfectants, and the like to mainly the cooling-tower-side circulation path, so that the cooling water introduced into the cooling-tower-side circulation path is improved in water quality. Unlike the conventional cooling-water circulation system, drainage equipment such as a drain tank does not need to be installed near the chiller machine, so that a simple structure can be obtained.

When the first connection pipe is provided at its one end with a differential pressure injector that is capable of introducing cooling water flowing through the first connection pipe into cooling water flowing through the pipe, under pressure lower than the cooling water flowing the pipe, the differential pressure injector introduces even cooling water flowing through the chiller-machine-side circulation path under pressure lower than the cooling water flowing through the cooling-tower-side circulation path into the cooling-tower-side circulation path.

When the differential pressure injector includes a small-diameter nozzle, a large-diameter nozzle, and an intake port, taking cooling water flowing through the pipe into the large-diameter nozzle from the intake port causes negative pressure to be generated in front of a discharge port of the small-diameter nozzle. The negative pressure causes suction force to draw out cooling water from the discharge port of the small-diameter nozzle at a higher flow velocity than the cooling water flowing through the first connection pipe. Then, cooling water taken in through the intake port is combined with the cooling water drawn out from the discharge port of the small-diameter nozzle to be injected into the pipe through the discharge port of the large-diameter nozzle. Thus, the differential pressure injector with a simple structure introduces cooling water flowing through the chiller-machine-side circulation path into the cooling-tower-side circulation path.

When the large-diameter nozzle is disposed so as to cover an outer peripheral surface of the small-diameter nozzle and the intake port is formed in a portion of the large-diameter nozzle, covering the outer peripheral surface of the small-diameter nozzle, cooling water is effectively taken into the large-diameter nozzle from the intake port to cause a larger negative pressure to be generated in front of the discharge port of the small-diameter nozzle. This further increases an injection force of the differential pressure injector.

When not only a plurality of the intake ports is formed along a circumferential direction around the axis of the large-diameter nozzle, but also each of the intake ports is formed in an elliptical shape having a minor axis along the circumferential direction around the axis of the large-diameter nozzle, cooling water is effectively taken into the large-diameter nozzle from each of the intake ports. This further increases an injection force of the differential pressure injector.

When the chiller-machine-side circulation path is provided in its feed path with a water impurity separation device provided with a drain port, and the first connection pipe connects the drain port and a return path of the cooling-tower-side circulation path, cooling water together with impurities separated by the water impurity separation device is introduced into the return path of the cooling-tower-side circulation path via the first connection pipe.

When the first connection pipe is provided with an electric valve for opening and closing the first connection pipe by opening and closing control of a control unit, the cooling water flowing through the chiller-machine-side circulation path can be automatically drained with a timer function and the like of the control unit.

When the first connection pipe is provided with a constant flow valve of a washer rubber type, clogging is prevented even when solid impurities pass through the constant flow valve at the time of draining cooling water.

When the cooling-tower-side circulation path and the chiller-machine-side circulation path are connected by a second connection pipe, cooling water circulating through the cooling-tower-side circulation path is introduced into the chiller-machine-side circulation path via the second connection pipe. This enables the cooling water contaminated in the chiller-machine-side circulation path and the cooling water improved in water quality in the cooling-tower-side circulation path to be easily exchanged with each other. As a result, corrosion (rust) of cooling pipes directly connected to a product, and hard scales including silica and the like adhering to the inside of pipes, are suppressed as compared with when cooling water is not exchanged. This prevents deterioration in cooling efficiency to lead to quality stability.

When the second connection pipe connects the feed path of the cooling-tower-side circulation path and a tank provided in the chiller machine, cooling water circulating through the cooling-tower-side circulation path is introduced into the tank of the chiller machine via the second connection pipe.

When the second connection pipe is provided at its one end with a float valve, the float valve automatically opens and closes the second connection pipe in accordance with vertical movement of a water surface in the tank.

BRIEF DESCRIPTION OF DRAWINGS

The present invention is further described in the detailed description which follows, in reference to the noted plurality of drawings by way of non-limiting examples of exemplary embodiments of the present invention, in which like reference numerals represent similar parts throughout the several views of the drawings, and wherein:

FIG. 1 is a general schematic view of a cooling water circulation system according to an example.

FIG. 2 is an enlarged view of a main part of FIG. 1.

FIG. 3 is an explanatory view for illustrating a first connection pipe according to the example.

FIG. 4 is an explanatory view for illustrating a differential pressure injector according to the example.

FIG. 5 is a longitudinal sectional view of the differential pressure injector.

FIG. 6 is a side view of a water impurity separation device according to the example, illustrating a part of it as a sectional view.

FIG. 7 is an explanatory view for illustrating a cooling-water circulation system according to another aspect.

FIG. 8 is an explanatory view for illustrating a conventional cooling-water replacing apparatus.

DESCRIPTION OF EMBODIMENT

The particulars shown herein are by way of example and for purposes of illustrative discussion of the embodiments of the present invention only and are presented in the cause of providing what is believed to be the most useful and readily understood description of the principles and conceptual aspects of the present invention. In this regard, no attempt is made to show structural details of the present invention in more detail than is necessary for the fundamental understanding of the present invention, the description is taken with the drawings making apparent to those skilled in the art how the forms of the present invention may be embodied in practice.

A cooling-water circulation system (1) according to the present embodiment includes a cooling-tower-side circulation path (2) for circulating cooling water between a cooling tower (5) and a chiller machine (6), and a chiller-machine-side circulation path (3) for circulating cooling water between the chiller machine (6) and a cooling target part (7). The cooling-tower-side circulation path (2) and the chiller-machine-side circulation path (3) are connected by a first connection pipe (31) for introducing cooling water circulating through the chiller-machine-side circulation path into the cooling-tower-side circulation path (e.g., refer to FIGS. 1 and 2).

The amount of cooling water introduced by the first connection pipe (31), timing of the introduction, and the like are not particularly limited. From the viewpoint of not affecting a circulating water temperature set in the chiller machine, the amount of cooling water introduced is preferably 0.1% to 5% (more preferably 0.1% to 3%, and particularly 0.1% to 2%) of the amount of the cooling water circulating through the chiller-machine-side circulation path (3).

The cooling-water circulation system according to the present embodiment may be configured such that the first connection pipe (31) is provided at its one end with a differential pressure injector (36) disposed in a pipe (60) constituting the cooling-tower-side circulation path (2), and such that the differential pressure injector is capable of introducing cooling water flowing through the first connection pipe (31) into cooling water flowing through the pipe (60), under pressure lower than the cooling water flowing through the pipe (60) (e.g., refer to FIG. 4, etc.). In this case, the differential pressure injector (36) may be configured to be able to introduce cooling water flowing through the first connection pipe (31) to the cooling water flowing through the pipe (60), at a smaller flow rate than the cooling water flowing through the pipe (60), for example.

The differential pressure injector (36) configured as described above may include a small-diameter nozzle (52) that is connected to one end of the first connection pipe (31) and that is disposed such that its axis is along a flow direction of cooling water in the pipe (60), a large-diameter nozzle (53) that is disposed such that its axis aligns with the axis of the small-diameter nozzle, and such that its discharge port is positioned downstream of a discharge port of the small-diameter nozzle in the flow direction of the cooling water in the pipe (60), and an intake port (54) for taking the cooling water flowing through the pipe (60) into the large-diameter nozzle (53) to generate negative pressure in front of the discharge port of the small-diameter nozzle (52), for example (e.g., refer to FIGS. 4 and 5, etc.).

The differential pressure injector (36) configured as described above may be configured such that the large-diameter nozzle (53) is disposed so as to cover an outer peripheral surface of the small-diameter nozzle (52), and such that the intake port (54) is formed in a portion of the large-diameter nozzle, covering the outer peripheral surface of the small-diameter nozzle, for example (e.g., refer to FIGS. 4 and 5, etc.). In addition, a plurality of the intake ports (54) may be formed along a circumferential direction around the axis of the large-diameter nozzle (53), and each of the intake ports may be formed in an elliptical shape having a minor axis along the circumferential direction around the axis of the large-diameter nozzle, for example.

The cooling-water circulation system according to the present embodiment may be configured such that the chiller-machine-side circulation path (3) is provided in its feed path (3a) with a water impurity separation device (17) for removing impurities contained in cooling water circulating the chiller-machine-side circulation path (3), the water impurity separation device (17) including a drain port (17a) for draining the cooling water together with separated impurities, and such that the first connection pipe (31) connects the drain port (17a) and the return path (2b) of the cooling-tower-side circulation path (2) (e.g., refer to FIG. 2, etc.), for example.

The cooling-water circulation system according to the present embodiment may be configured such that the first connection pipe (31) is provided with an electric valve (33) for opening and closing the first connection pipe by opening and closing control of a control unit (32), for example (e.g., refer to FIG. 3, etc.). In addition, the first connection pipe (31) may be configured to include a constant flow valve (34) of a washer rubber type, for example (e.g., refer to FIG. 3, etc.).

The cooling-water circulation system according to the present embodiment may be configured such that the cooling-tower-side circulation path (2) and the chiller-machine-side circulation path (3) are connected by a second connection pipe (38) for introducing cooling water circulating cooling-tower-side circulation path into the chiller-machine-side circulation path, for example (e.g., refer to FIG. 2, etc.).

In the aspect described above, the second connection pipe (38) may connect the feed path (2a) of the cooling-tower-side circulation path (2) and the tank (6a) provided in the chiller machine (6), for example (e.g., refer to FIG. 2, etc.). In this case, the second connection pipe (38) may be provided at its one end with a float valve (39) for opening and closing the second connection pipe in accordance with vertical movement of a water surface in the tank (6a), for example.

The reference numeral in parentheses of each component described in the above embodiment indicates a correspondence with a specific component described in an example to be described below.

EXAMPLE

Hereinafter, the present invention will be described in detail using an example with reference to the drawings.

(1) Configuration of Cooling Water Circulation System

As illustrated in FIG. 1, a cooling-water circulation system 1 according to the present example includes a cooling-tower-side circulation path 2 (also referred to as a “primary circulation path”) for circulating cooling water between a cooling tower 5 and a chiller machine 6, and a chiller-machine-side circulation path 3 (also referred to as a “secondary circulation path”) for circulating the cooling water between the chiller machine 6 and a cooling target part 7. Examples of the cooling target part 7 include an injection molding device, a press working device, a welding device, a heating device, a trimming device, and the like.

The cooling tower 5 includes a water sprinkling tank 5a for storing and sprinkling cooling water increased in temperature fed from the chiller machine 6, a filling material 5b for cooling the water sprinkled from the water sprinkling tank 5a with air, a blower 5c for taking in outside air through a suction port to allow the outside air to pass through the inside of the filling material 5b, and a water tank 5d for storing the cooling water dropped while being cooled by the filling material 5b. The water tank 5d is provided in its inside with a straight pipe 41B made of porous ceramic, constituting a microbubble generator 40B for generating microbubbles in cooling water in the water tank 5d, and an injector 9 for removing precipitate such as slime precipitated on the bottom of the water tank 5d. In addition, a multifunctional net 10 is stretched so as to cover the suction port and the water sprinkling tank 5a of the cooling tower 5. The multifunction net 10 not only prevents algae, slime, legionella bacteria, and the like from occurring in the cooling tower 5 but also improves cooling efficiency therein.

The chiller machine 6 includes a tank 6a for storing cooling water increased in temperature fed from the cooling target part 7, and a heat exchanger 6b for cooling the cooling water in the tank 6a. The tank 6a is provided in its inside with a straight pipe 41C made of porous ceramics, constituting a microbubble generator 40C for generating microbubbles in cooling water in the tank 6a.

The cooling-tower-side circulation path 2 includes a feed path 2a that is connected at one end to the water tank 5d of the cooling tower 5 and at the other end to the heat exchanger 6b of the chiller machine 6, and a return path 2b that has one end connected to the heat exchanger 6b of the chiller machine 6 and the other end connected to the water sprinkling tank 5a of the cooling tower 5. The feed path 2a is provided with a pressure pump 12 for pumping the cooling water in the water tank 5d of the cooling tower 5 toward the heat exchanger 6b of the chiller machine 6. In addition, an introduction pipe 13 has one end connected to the injector 9 and the other end connected to the feed path 2a upstream of the pressure pump 12. The introduction pipe 13 is provided with a pressure feed pump 14 for pumping the cooling water in the water tank 5d of the cooling tower 5 toward the injector 9. Then, the injector 9 injects the cooling water pumped by the pressure pump 14 to remove precipitate precipitating on the bottom of the water tank 5d.

The introduction pipe 13 includes a basket filter 16 containing a water treatment agent made of an inorganic substance or the like, a water impurity separation device 17 for removing impurities contained in the cooling water, and a tourmaline treatment device 18 for forming tourmaline-treated water by bringing the cooling water into contact with tourmaline granules. The water impurity separation device 17 has a drain port 17a connected to a drain pipe 21 that is opened and closed by an on-off valve 22. The on-off valve 22 is controlled to be opened and closed by a control unit 24 in accordance with a detection value from a sensor 23 for detecting electric conductivity of cooling water. When the drain pipe 21 is opened, the cooling water is drained together with impurities from the drain port 17a of the water impurity separation device 17. The introduction pipe 13 is provided with a bypass path 25, and the bypass path 25 is provided with a magnetic water treatment device 19 for magnetically treating cooling water.

While the water impurity separation device 17 provided in the introduction pipe 13 is shown in the present example, the present invention is not limited to this. For example, the water impurity separation device 17 may be provided in the return path 2b (or the feed path 2a) of the cooling tower circulation path 2 instead of or in addition to the introduction pipe 13, as illustrated in FIG. 1 by an imaginary line. While the tourmaline treatment device 18 provided in the introduction pipe 13 is shown in the present example, the present invention is not limited to this. For example, the tourmaline treatment device 18 may be provided in the feed path 2a (or the return path 2b) of the cooling-tower-side circulation path 2 instead of or in addition to the introduction pipe 13, as illustrated in FIG. 1 by an imaginary line. In addition, the tourmaline treatment device 18 may be provided in the return path 3b (or the feed path 3a) described below of the chiller-machine-side circulation path 3.

The chiller-machine-side circulation path 3 includes a feed path 3a that has one end connected to the tank 6a of the chiller machine 6 and the other end connected to the cooling target part 7, and a return path 3b that has one end connected to the cooling target part 7 and the other end connected to the tank 6a of the chiller machine 6. The feed path 3a is provided with a pressure pump 26 for pumping cooling water in the tank 6a of the chiller machine 6 toward the cooling target part 7. In addition, a bypass path 27 is provided downstream of the pressure pump 26 in the feed path 3a. The bypass path 27 includes the water impurity separation device 17 for removing impurities contained in cooling water, and the microbubble generator 40A for generating microbubbles in cooling water. The microbubble generator 40A includes a straight pipe 41A made of porous ceramics, and a container 53 containing the tourmaline granules. Thus, the microbubble generator 40A has not only a function of generating microbubbles in cooling water but also a function of bringing the cooling water into contact with tourmaline granules to form tourmaline-treated water.

As illustrated in FIG. 6, the water impurity separation device 17 includes a housing 70 provided with an inflow port 70a and an outflow port 70b. The housing 70 is provided in its inside with a baffle plate 71 such that its internal space is vertically partitioned into an upper filtration chamber S1 and a lower precipitation chamber S2. The upper filtration chamber S1 contains a plurality of filter media 72 therein. The housing 70 is provided at its bottom with a drain port 17a communicating with the lower precipitation chamber S2.

As illustrated in FIG. 2, the cooling-tower-side circulation path 2 and the chiller-machine-side circulation path 3 are connected by a first connection pipe 31 for introducing cooling water circulating through the chiller-machine-side circulation path 3 into the cooling-tower-side circulation path 2. The first connection pipe 31 connects the drain port 17a of the water impurity separation device 17 and the return path 2b of the cooling-tower-side circulation path 2.

The first connection pipe 31 is provided with an electric valve 33 that opens and closes the first connection pipe 31 by opening and closing control of a control unit 32. The control unit 32 has a timer function that enables a drainage time period and the amount of exchanging drainage to be arbitrarily set in accordance with water quality conditions, a temperature setting state, and the like of cooling water. The first connection pipe 31 is provided with a constant flow valve 34 of a washer rubber type. As illustrated in FIG. 3, the first connection pipe 31 is provided with a ball valve 43, a PVC Y-type strainer 44, a filter 45, a sight glass 46, a tube fitting 47, a transparent Teflon (registered trademark) tube 48, a chuck valve 49, and a ball valve 50.

The bail valve 43 uses a bore diameter of 25A because the amount of water taken can be secured by increasing its water intake side in size. The PVC Y-type strainer 44 is provided for preventing damage to equipment when a solid matter enters the equipment, and is made of a transparent material allowing a clogging state to be visually checked. The filter 45 uses a filter of 20 mesh that does not affect drainage apparatuses because a common filter of 40 mesh is likely to cause clogging. The electric valve 33 uses a ball valve type because a diaphragm type may cause trouble such as biting. Further, the sight glass 46 not only allows transparent glass and a water wheel to be easily and visually checked for checking whether water is drained, or the with ease, but also allows a flow rate to be easily checked. The constant flow valve 34 of a washer type is less likely to cause clogging on the assumption of entry of solid impurities. The tube fitting 47 is used to improve maintenance efficiency. The transparent Teflon (registered trademark) tube 48 is resistant to hot water and has weather resistance, and enables a visual check for a state of contamination in water. The chuck valve 49 uses a lift type with high accuracy of reverse-flow prevention because a reverse-flow action occurs during stopping of the device. The ball valve 50 uses a ball valve of size 15A because a drain port with a smaller diameter allows water to be smoothly drained.

As illustrated in FIG. 4, the first connection pipe 31 is provided at its one end with a differential pressure injector 36 disposed in a pipe 60 (e.g., having an inner diameter of 70.3 mm, and a longitudinal sectional area of 3879.5 mm²) constituting the cooling-tower-side circulation path 2. The differential pressure injector 36 is configured to be able to introduce cooling water flowing through the first connection pipe 31 to the cooling water flowing through the pipe 60, under a lower pressure and at a smaller flow rate than the cooling water flowing through the pipe 60.

The differential pressure injector 36 includes a small-diameter nozzle 52 that is connected to one end of the first connection pipe 31 and that is disposed such that its axis is along a flow direction of cooling water in the pipe 60, a large-diameter nozzle 54 that is disposed such that its axis aligns with the axis of the small-diameter nozzle 52, and such that its discharge port 53a is positioned downstream of a discharge port 52a of the small-diameter nozzle 52 in the flow direction of the cooling water in the pipe 60, and an intake port 54 for taking the cooling water flowing through the pipe 60 into the large-diameter nozzle 53 to generate negative pressure in front of the discharge port 52a of the small-diameter nozzle 52 (refer to FIG. 5). The small-diameter nozzle 52 has a nozzle hole that decreases in diameter toward the discharge port 52a (e.g., having an inner diameter of 5 mm). The large-diameter nozzle 53 has a nozzle hole that increase in diameter toward the discharge port 53a. In addition, the discharge port 53a of the large-diameter nozzle 53 has an opening area more than an opening area of the discharge port 52a of the small-diameter nozzle 52.

The large-diameter nozzle 53 is disposed so as to cover an outer peripheral surface of the small-diameter nozzle 52. The intake port 54 is formed in a portion (specifically, a rear end portion of the large-diameter nozzle 53, being axially opposite to the discharge port 53a) of the large-diameter nozzle 53, covering the outer circumferential surface of the small-diameter nozzle 52. In addition, a plurality (e.g., six) of the intake ports 54 is formed along a circumferential direction around the axis of the large-diameter nozzle 53. Further, each of the intake ports 54 is formed in an elliptical shape (e.g., having an ellipse area of 75.39 mm2) having a minor axis along the circumferential direction around the axis of the large-diameter nozzle 53.

As illustrated in FIG. 2, the cooling tower-side circulation path 2 and the chiller-machine-side circulation path 3 are connected by a second connection pipe 38 for introducing cooling water circulating through the cooling-tower-side circulation path 2 into the chiller machine-side circulation path 3. The second connection pipe 38 connects the feed path 2a of the cooling-tower-side circulation path 2 and the tank 6a of the chiller machine 6. The second connection pipe 38 is provided at its one end with a float valve 39 for opening and closing the second connection pipe in accordance with vertical movement of the water surface in the tank 6a.

(2) Action of cooling-water circulation system

Next, action of the cooling water circulation system 1 having the above configuration will be described. As illustrated in FIG. 1, cooling water circulating in the cooling-tower-side circulation path 2 is improved in water quality not only when flowing through the introduction pipe 13 by action of the basket filter 16, the water impurity separation device 17, the tourmaline treatment device 18, and the magnetic water treatment device 19, but also when being stored in the water tank 5d of the cooling tower 5 by action of the microbubble generator 40B. This causes the cooling water to not only be excellent in rust prevention and scaling resistance, but also have a cleaning function. Meanwhile, cooling water circulating through the chiller-machine-side circulation path 3 is improved in water quality not only by action of the water impurity separation device 17 and the microbubble generator 40A with a tourmaline treatment function, but also by action of the microbubble generator 40C when being stored in the tank 6a of the chiller machine 6. This causes the cooling water to not only be excellent in rust prevention and scaling resistance, but also have a cleaning function.

Then, circulating the cooling water improved in water quality through the respective circulation paths 2 and 3 suppresses the following problems due to deterioration in water quality of cooling water: adhesion, deposition, and clogging of a flow channel, of scales; corrosion, rust, and water leakage; and occurrence of slime and algae, in a mold cooling hole, a cooling pipe, a heat exchanger, and the like. As a result, the following various merits can be obtained: stable quality of a molding (a mold can be maintained at a constant temperature, and a silver defect due to insufficient cooling is less likely to occur); power saving and energy saving (large reduction in power consumption by increase in a heat exchange rate of a heat exchanger, reduction in the amount of emission of CO₂through power saving and water saving, and reduction of trouble about abnormal high pressure of a heat exchanger); and large reduction in facility management cost (reduction of electricity charges for facilities, reduction of chemical cleaning cost, and reduction of cleaning maintenance cost).

In addition, the cooling-water circulation system 1 is configured such that when the electric valve 33 is opened by a timer function of the control unit 32, cooling water together with impurities is introduced into the return path 2b of the cooling-tower-side circulation path 2 from the drain port 17a of the water impurity separation device 17 via the first connection pipe 31. At this time, the differential pressure injector 36 injects cooling water (with a water pressure of 0.3 MPa, and at a flow rate of 1.8 L/min) flowing through the first connection pipe 31, under a lower pressure and at a smaller flow rate than the cooling water (with a water pressure of 0.4 MPa, and at a flow rate of 120 L/min) flowing through the pipe 60 constituting the cooling-tower-side circulation path 2, into the cooling water flowing through the pipe 60. Meanwhile, when the float valve 39 is operated in accordance with descent of the water surface of the tank 6a of the chiller machine 6, the cooling water flowing through the feed path 2a of the cooling-tower-side circulation path 2 is introduced to the tank 6a via the second connection pipe 38. That is, the cooling water contaminated in the chiller-machine-side circulation path 3 and the cooling water improved in water quality in the cooling-tower-side circulation path 2 are exchanged with each other.

The amount of water discharged from the water impurity separation device 17 is preferably set within 2% of the amount of circulating water in the chiller-machine-side circulation path 3 so as not to affect cooling efficiency of the chiller machine 6 in the chiller-machine-side circulation path 3 and the water is introduced into the return path 2b of the cooling-tower-side circulation path 2 from the constant flow valve 34 through the chuck valve 49. However, the amount of circulating water in the heat exchanger 6b varies by using the chiller machine 6, so that the constant flow valve 34 needs to be selected in terms of a drainage flow rate corresponding to specifications of the water impurity separation device 17.

Here, action of the differential pressure injector 36 will be described. As illustrated in FIG. 4, in the first connection pipe 31, drainage water with an amount of 1.8 L/min controlled by the constant flow valve 34 is accelerated to a flow velocity of 2.5 m/min in the tube 56 (having an inner diameter of 5 mm) while the amount of 1.8 L/min is maintained, and is maintained at the flow velocity of 2.5 m/sec in the small-diameter nozzle 52 while having the amount of 1.8 L/min. Meanwhile, when a part (an amount of 10 L/min of water) of cooling water flowing through the pipe 60, having a total amount of 120 L/min, is taken into the large-diameter nozzle 53 from the intake port 54, negative pressure is generated in front of the discharge port 52a of the small-diameter nozzle 52. Suction force caused by the negative pressure (a suction force five times that when the intake port 54 is not provided) draws out the drainage water flowing through the small-diameter nozzle 52 from the discharge port 52a while the drainage water still has the amount of 1.8 L/min and is maintained at the flow velocity of 2.5 m/sec. The drainage water drawn with the amount of 1.8 L/min merges with cooling water with an amount of 10 L/min taken from the intake port 54 to become water with a total amount of 11.8L/min while being accelerated to a flow velocity of 2.5 m/sec in the large-diameter nozzle 53, and then is discharged (injected) into the pipe 60 from the discharge port 53a of the large-diameter nozzle 53. The cooling water with the total amount of 11.8 L/min discharged from the large-diameter nozzle 53a into the pipe 60 merges with cooling water with an amount of 110 L/min flowing outside the differential pressure injector 36 to become water with a total amount of 121.8 L/min at a flow velocity of 0.522 m/sec, and then is fed to the water sprinkling tank 5a in an upper portion of the cooling tower 5 (refer to FIG. 1).

(3) Effect of Example

The cooling-water circulation system 1 of the present example is configured such that the cooling-tower-side circulation path 2 and the chiller-machine-side circulation path 3 are connected by the first connection pipe 31 for introducing cooling water circulating through the chiller-machine-side circulation path 3 into the cooling-tower-side circulation path 2. This causes the cooling water circulating through the chiller-machine-side circulation path 3 to be introduced into the cooling-tower-side circulation path 2 via the first connection pipe 31. Then, manufacturers usually manage maintenance by administering preservatives, disinfectants, and the like to mainly the cooling-tower-side circulation path 2, so that the cooling water introduced into the cooling-tower-side circulation path 2 is improved in water quality. Unlike the conventional cooling-water circulation system, drainage equipment such as a drain tank does not need to be installed near the chiller machine 6, so that a simple structure can be obtained.

The present example is configured such that the first connection pipe 31 is provided at its one end with the differential pressure injector 36, and such that the differential pressure injector 36 is able to introduce cooling water flowing through the first connection pipe 31 to the cooling water flowing through the pipe 60, under a lower pressure than the cooling water flowing through the pipe 60. As a result, even when cooling water flowing through the chiller-machine-side circulation path 3 is under pressure lower than cooling water flowing through the cooling-tower-side circulation path 2, the differential pressure injector introduces the cooling water flowing through the chiller-machine-side circulation path 3 into the cooling-tower-side circulation path 2.

The present example is configured such that the differential pressure injector 36 includes the small-diameter nozzle 52, the large-diameter nozzle 53, and the intake port 54. As a result, taking cooling water flowing through the pipe 60 into the large-diameter nozzle 53 from the intake port 54 causes negative pressure to be generated in front of the discharge port 52a of the small-diameter nozzle 52. The negative pressure causes suction force to draw out cooling water from the discharge port 52a of the small-diameter nozzle 52 at a higher flow velocity (e.g., a flow velocity about four times a flow velocity of cooling water flowing through the first connection pipe 31) than the cooling water flowing through the first connection pipe 31. Then, cooling water taken in through the intake port 54 is combined with cooling water drawn out from the discharge port 52a of the small-diameter nozzle 52 to be injected into the pipe 60 through the discharge port 53a of the large-diameter nozzle 63. Thus, the differential pressure injector 36 with a simple structure introduces cooling water flowing through the chiller-machine-side circulation path 3 into the cooling-tower-side circulation path 2.

The present example is configured such that the large-diameter nozzle 53 is disposed so as to cover the outer peripheral surface of the small-diameter nozzle 52, and such that the intake port 54 is formed in a portion of the large-diameter nozzle 53, covering the outer peripheral surface of the small-diameter nozzle 52. As a result, the cooling water is effectively taken into the large-diameter nozzle 53 from the intake port 54 to generate a larger negative pressure in front of the discharge port of the small-diameter nozzle 52. This further increases an injection force of the differential pressure injector 36.

The present example is configured such that a plurality of the intake ports 54 is formed along the circumferential direction around the axis of the large-diameter nozzle 53, and such that each of the intake ports is formed in an elliptical shape having a minor axis along the circumferential direction around the axis of the large-diameter nozzle 53. As a result, the cooling water is more effectively taken into the large-diameter nozzle 53 from the intake port 54. This further increases an injection force of the differential pressure injector 36.

The present example is configured such that the chiller-machine-side circulation path 3 is provided in its feed path 3a with the water impurity separation device 17 that includes the drain port 17a, and such that the first connection pipe 31 connects the drain port 17a and the return path 2b of the cooling-tower-side circulation path 2. As a result, the cooling water is introduced into the return path 2b of the cooling-tower-side circulation path 2, together with impurities separated by the water impurity separation device 17, via the first connection pipe 31.

The present example is configured such that the first connection pipe 31 is provided with the electric valve 33 that opens and closes the first connection pipe 31 by opening and closing control of the control unit 32. As a result, the cooling water flowing through the chiller-machine-side circulation path 3 can be automatically drained with the timer function and the like of the control unit 32.

The present example is configured such that the first connection pipe 31 is provided with the constant flow valve 34 of a washer rubber type. This prevents clogging even when solid impurities pass through the constant flow valve 34 at the time of draining cooling water.

The present example is configured such that the cooling-tower-side circulation path 2 and the chiller-machine-side circulation path 3 are connected by the second connection pipe 38. This causes the cooling water circulating through the cooling-tower-side circulation path 2 to be introduced into the chiller-machine-side circulation path 3 via the second connection pipe 38. Accordingly, the cooling water contaminated in the chiller-machine-side circulation path 3 and the cooling water improved in water quality in the cooling-tower-side circulation path 2 can be easily exchanged with each other. As a result, corrosion (rust) of cooling pipes directly connected to a product, and hard scales including silica and the like adhering to the inside of pipes, are suppressed as compared with when cooling water is not exchanged. This prevents deterioration in cooling efficiency to lead to quality stability.

The present example is configured such that the second connection pipe 38 connects the feed path 2a of the cooling-tower-side circulation path 2 and the tank 6a provided in the chiller machine 6. This causes the cooling water circulating through the cooling-tower-side circulation path 2 to be introduced into the tank 6a of the chiller machine 6 via the second connection pipe 38.

The present example is configured such that the second connection pipe 38 is provided at its one end with the float valve 39. Accordingly, the float valve 39 automatically opens and closes the second connecting pipe 38 in accordance with vertical movement of a water surface in the tank 6a.

The present invention is not limited to the example described above, and can be variously modified within the scope of the present invention depending on purpose and use. That is, while the above example shows an aspect in which the first connection pipe 31 is provided at its one end with the differential pressure injector 36 disposed in the pipe 60, for example, the present invention is not limited thereto. When circulatory pressure in the chiller-machine-side circulation path 3 is equal to or more than circulatory pressure in the cooling-tower-side circulation path 2, the first connection pipe 31 may be directly connected at one end to an outer peripheral portion of the pipe 60 without providing the differential pressure injector 36 at the one end of the first connection pipe 31, as illustrated in FIG. 7, for example.

While the above example shows the cooling-water circulation system 1 in which the cooling water contaminated in the chiller-machine-side circulation path 3 and the cooling water improved in water quality in the cooling-tower-side circulation path 2 are exchanged with each other, the present invention is not limited thereto. The cooling-water circulation system may be configured such that while the cooling water contaminated in the chiller-machine-side circulation path 3 is introduced into the cooling-tower-side circulation path 2, cooling water prepared separately from the cooling water in the cooling-tower-side circulation path 2 is introduced into the chiller-machine-side circulation path 3, for example.

While the above example shows the first connection pipe 31 that connects the drain port 17a of the water impurity separation device 17 and the cooling-tower-side circulation path 2, the present invention is not limited thereto. The first connection pipe may directly connect the chiller-machine-side circulation path 3 (the feed path 3a or the return path 3b) and the cooling-tower-side circulation path 2 (the feed path 2a or the return path 2b), for example.

While the above example shows the second connection pipe 38 that connects the cooling-tower-side circulation path 2 and the tank 6a of the chiller machine 6, the present invention is not limited thereto. The second connection pipe may directly connect the cooling-tower-side circulation path 2 (the feed path 2a or the return path 2b) and chiller-tower-side circulation path 3 (the feed path 3a or the return path 3b), for example.

It is noted that the foregoing examples have been provided merely for the purpose of explanation and are in no way to be construed as limiting of the present invention. While the present invention has been described with reference to exemplary embodiments, it is understood that the words which have been used herein are words of description and illustration, rather than words of limitation. Changes may be made, within the purview of the appended claims, as presently stated and as amended, without departing from the scope and spirit of the present invention in its aspects. Although the present invention has been described herein with reference to particular structures, materials and embodiments, the present invention is not intended to be limited to the particulars disclosed herein; rather, the present invention extends to all functionally equivalent structures, methods and uses, such as are within the scope of the appended claims.

The present invention is not limited to the above-described embodiments, and various variations and modifications may be possible without departing from the scope of the present invention.

INDUSTRIAL APPLICABILITY

The present invention is widely used as a technique for draining cooling water circulating through a chiller-machine-side circulation path. In particular, it is suitably used as a technique for exchanging cooling water contaminated in the chiller-machine-side circulation path with the cooling water improved in water quality in the cooling-tower-side circulation path.

REFERENCE SIGNS LIST

1 cooling water circulation system

2 cooling-tower-side circulation path

3 chiller-machine-side circulation path

5 cooling tower

6 chiller machine

6
a tank

7 cooling target part

17 water impurity separation device

17
a drain port

31 first connection pipe

32 control unit

33 electric valve

34 constant flow valve

36 differential pressure injector

38 second connection pipe

39 float valve

52 small-diameter nozzle

53 large-diameter nozzle

54 intake port

60 pipe

COOLING-WATER CIRCULATION SYSTEM

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CPC

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