Absorption type refrigeration system

Abstract

To provide an absorption type refrigeration system capable of suppressing increase in electric power consumption and shortening of a service life of a pump.SOLUTION: An absorption type refrigeration system includes: water supply piping 24 for sending out cooling water to a lower water tank 23; a float valve 25 for opening / closing the water supply piping 24; a water level sensor 26 for detecting a water level of the lower water tank 23; a control device that stops a cooling water pump P when a water level detected by the water level sensor 26 is lower than a first level, and starts an operation of the cooling water pump P when the water level detected through the water level sensor 26 is equal to or higher than a second level exceeding the first level; and second water supply piping 27 provided separately from the water supply piping 24 to send out the cooling water to the lower water tank 23. When stop frequency or operation start frequency of the cooling water pump P reaches predetermined frequency or more, the control device sends out the cooling water into the lower water tank 23 through the second water supply piping 27.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to an absorption refrigeration system. [Background technology]

[0002] Conventionally, there has been known an absorption refrigeration system having an absorption chiller (including an absorption chiller / heater with a heating function) and a cooling tower that supplies cooling water to the absorption chiller (see, for example, Patent Document 1). In this absorption refrigeration system, when the absorption chiller is installed or when switching from heating operation to cooling operation, water filling is performed to fill the water passage part in the absorption chiller with cooling water. The absorption refrigeration system is equipped with a pump that pressure-feeds cooling water from the cooling tower to the absorption chiller, and when water filling is performed, cooling water is sent from the cooling tower to the absorption chiller by the pump to fill the water passage part with cooling water. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 7-2296 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in conventional absorption refrigeration systems, the pump has to be started and stopped repeatedly when filling the refrigeration tank with water. This causes a large amount of power consumption and shortens the life of the pump.

[0005] The present invention has been made to solve such problems, and an object of the present invention is to provide an absorption refrigeration system that can suppress an increase in power consumption and a shortening of the pump's lifespan. [Means for solving the problem]

[0006] The absorption refrigeration system of the present invention comprises an absorption chiller, a cooling tower which supplies cooling water to a water passage section of the absorption chiller, and a pump which serves as a power source for sending cooling water in a water tank provided in the cooling tower to the absorption chiller, and which performs water filling to fill the water passage section with cooling water from a state in which the water passage section is not filled with cooling water, and further comprises a water supply piping for sending cooling water to the water tank, and when the water level in the water tank is below a predetermined level, the water supply piping is opened to take in the cooling water into the water tank, and when the water level in the water tank exceeds the predetermined level, the water supply piping is closed to let the cooling water flow. The system comprises a float valve which prohibits flow into the water tank, a water level sensor which detects the water level of the water tank, a control means which stops the pump when the water level detected by the water level sensor is below a first level and starts operation of the pump when the water level detected by the water level sensor is at or above a second level which is higher than the first level, and a second water supply pipe which is provided separately from the water supply pipe and which supplies cooling water to the water tank, and the control means supplies cooling water into the water tank through the second water supply pipe when the number of times the pump has stopped or started reaches a predetermined number or more. Effect of the Invention

[0007] According to the present invention, it is possible to provide an absorption refrigeration system capable of suppressing an increase in power consumption and a shortened life of a pump. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a configuration diagram showing an absorption refrigeration system according to a first embodiment. [Diagram 2] FIG. 2 is a configuration diagram showing the vicinity of the lower water tank of the cooling tower shown in FIG. [Diagram 3] 4 is a flowchart showing control of the control device according to the first embodiment. [Figure 4] FIG. 11 is a configuration diagram showing the vicinity of a lower water tank of a cooling tower according to a second embodiment. [Diagram 5] 10 is a flowchart showing a control of a control device according to a second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] The present invention will be described below along with preferred embodiments. Note that the present invention is not limited to the embodiments shown below, and can be modified as appropriate within the scope of the present invention. In addition, in the embodiments shown below, some configurations are omitted from illustration and description, but it goes without saying that publicly known or well-known technologies are appropriately applied to the details of the omitted technologies within the scope of no contradiction with the contents described below.

[0010] FIG. 1 is a configuration diagram showing an absorption refrigeration system according to a first embodiment. As shown in FIG. 1, the absorption refrigeration system 1 includes an absorption chiller 10, a cooling tower 20, a cooling water pump (pump) P, a control device (control means) 30, and first and second circulation pipes L1 and L2. The first circulation pipe L1 is a pipe for sending cooling water from the cooling tower 20 to the absorption chiller 10. The second circulation pipe L2 is a pipe for returning cooling water from the absorption chiller 10 to the cooling tower 20. The cooling water pump P is provided in the first circulation pipe L1 and serves as a power source for sending cooling water from the cooling tower 20 to the absorption chiller 10.

[0011] The absorption chiller 10 has a circulation cycle consisting of an evaporator, an absorber, a regenerator and a condenser, and cools the refrigerant by this circulation cycle. Such an absorption chiller 10 is equipped with a water passing section 11. The water passing section 11 is for passing cooling water discharged from a cooling tower 20 through the absorption chiller 10, and is a section through which the cooling water flows when the absorption chiller 10 is filled with cooling water during cooling operation.

[0012] The water passage section 11 includes a first water passage section 11a and a second water passage section 11b. The first water passage section 11a is connected to the first circulation pipe L1 at its upstream side and to the second water passage section 11b at its downstream side. The second water passage section 11b is connected to the first water passage section 11a at its upstream side and to the second circulation pipe L2 at its downstream side.

[0013] The first water passage 11a is provided, for example, in the absorber, and serves to liquefy the refrigerant vapor evaporated in the evaporator. The second water passage 11b is provided, for example, in the condenser, and serves to liquefy the refrigerant vapor evaporated in the regenerator.

[0014] Such a water passage section 11 takes in cooling water from the cooling tower 20 through the first circulation piping L1, and returns the cooling water to the cooling tower 20 again through the second circulation piping L2 after being used in the first and second water passage sections 11a and 11b. Note that, although the absorption refrigeration system 1 in the example shown in Fig. 1 includes an absorption chiller 10 having a cooling function, this absorption chiller 10 may also be an absorption chiller / heater further having a heating function.

[0015] The cooling tower 20 supplies cooling water to the absorption chiller 10, and includes an upper water tank 21, a filler 22, and a lower water tank (water tank) 23.

[0016] The upper water tank 21 temporarily stores the cooling water returning from the absorption chiller 10. The upper water tank 21 also includes a spray unit (not shown) that sprays the temporarily stored cooling water onto the filler 22. The filler 22 lowers the cooling water temperature by exposing the cooling water sprayed from the upper water tank 21 to the outside air. The lower water tank 23 temporarily stores the cooling water whose temperature has been lowered by passing through the filler 22.

[0017] Fig. 2 is a configuration diagram showing the vicinity of the lower water tank 23 of the cooling tower 20 shown in Fig. 1. As shown in Fig. 2, the cooling tower 20 further includes a water supply pipe 24, a float valve 25, and a water level sensor 26. In addition, as shown in Fig. 2, a first circulation pipe L1 is connected to the vicinity of the lower end of the lower water tank 23.

[0018] The water supply pipe 24 is connected to, for example, a water pipe or the like, and serves to send cooling water to the lower water tank 23. The float valve 25 opens and closes the water supply pipe 24. When the water level in the lower water tank 23 is below a predetermined level, the float valve 25 opens the water supply pipe 24 to take in cooling water into the lower water tank 23. On the other hand, when the water level in the lower water tank 23 exceeds the predetermined level, the float valve 25 closes the water supply pipe 24 to prohibit the cooling water from flowing into the lower water tank 23. Here, the predetermined level is higher than a second level and lower than a third level, which will be described later.

[0019] The water level sensor 26 detects the water level of the lower water tank 23, and has a first contact 26a and a second contact 26b. The first contact 26a is for determining whether the water level is equal to or higher than a first level. When the first contact 26a is immersed in water, the water level sensor 26 outputs a signal to that effect to the control device 30 (see FIG. 1). The first level is set to a height that prevents air from entering the first circulation pipe L1.

[0020] The second contact 26b is for judging whether the water level is equal to or higher than a second level that exceeds the first level. When the second contact 26b is immersed in water, the water level sensor 26 outputs a signal to that effect to the control device 30.

[0021] Here, the control device 30 has a function of determining the water level based on a signal from the water level sensor 26, and controls the operation of the cooling water pump P according to the water level. That is, when the control device 30 determines that the water level is below the first level based on the signal from the water level sensor 26, it stops the cooling water pump P to prevent air from being trapped in the cooling water pump P. In addition, once the control device 30 stops the cooling water pump P, it keeps the cooling water pump P stopped until it can determine that the water level has reached the second level or higher based on the signal from the water level sensor 26, and starts the operation of the cooling water pump P when it determines that the water level has reached the second level.

[0022] Here, in the absorption refrigeration system 1, the water passage section 11 of the absorption chiller 10 before installation or during heating operation is not filled with cooling water. For this reason, when the absorption chiller 10 is installed or when switching from heating operation to cooling operation, the absorption refrigeration system 1 fills the water passage section 11 with cooling water. However, the control device 30 may repeatedly start and stop the cooling water pump P during water filling.

[0023] That is, during water filling, cooling water is taken into the lower water tank 23 from the water supply pipe 24, but the amount of cooling water pumped by the cooling water pump P is sufficiently larger than the amount of cooling water supplied from the water supply pipe 24, so that the water level frequently alternates between being below the first level and being above the second level. In particular, if the water level repeatedly alternates between being below the first level and being above the second level, the cooling water pump P will be started and stopped frequently, for example, several hundred times, until water filling is complete. As a result, the absorption refrigeration system 1 consumes a lot of power due to the starting and stopping, and the pump life is shortened.

[0024] Therefore, the absorption refrigeration system 1 according to the first embodiment is provided with a second water supply pipe 27 connected to a water pipe or the like in the cooling tower 20, as shown in Fig. 2. The second water supply pipe 27 is provided separately from the water supply pipe 24, and is for sending cooling water to the lower water tank 23 at least when the tank is filled with water. The second water supply pipe 27 is provided with a control valve 27a for opening and closing the flow path.

[0025] The control device 30 according to the first embodiment further includes a function for controlling the opening and closing of the control valve 27a, and a function for counting the number of times the cooling water pump P stops or starts operating during water filling (e.g., from the start of water filling or per unit time). When the number of times the cooling water pump P stops or starts operating during water filling reaches a predetermined number or more, the control device 30 opens the control valve 27a to open the second water supply piping 27 and starts sending out the cooling water from the second water supply piping 27.

[0026] The overflow pipe 28 discharges the cooling water when the water level in the lower water tank 23 reaches a third level that exceeds the second level. The overflow pipe 28 prevents the cooling water from overflowing from the lower water tank 23. Here, the third level is a water level higher than a predetermined level.

[0027] The amount of cooling water discharged per unit time from the overflow pipe 28 is set to be equal to or greater than the amount of cooling water per unit time flowing into the lower water tank 23 through the water supply pipe 24 and the second water supply pipe 27. This ensures that the overflow pipe 28 can ensure a sufficient discharge amount even if the float valve 25 fails, thereby preventing the cooling water from overflowing from the lower water tank 23.

[0028] Here, it is more preferable that (amount pumped by the cooling water pump P per unit time)≦(amount of cooling water flowing into the lower water tank 23 per unit time through the water supply pipe 24 and the second water supply pipe 27)≦(amount obtained by adding the amount of cooling water pumped per unit time discharged through the overflow pipe 28 to the amount pumped). When cooling water is being discharged from the overflow pipe 28, the water level exceeds the second level, and therefore the cooling water pump P is operating. Therefore, by doing as described above, a more appropriate state can be achieved that also takes into account the operation of the cooling water pump P.

[0029] Fig. 3 is a flowchart showing the control of the control device 30 according to the first embodiment. The flowchart shown in Fig. 3 is executed at the start of water filling. First, the control device 30 turns on the cooling water pump P (starts operation) (S1).

[0030] Next, the control device 30 judges whether the water level is equal to or higher than the first level (S2). If the water level is equal to or higher than the first level (S2: YES), the process proceeds to step S7. On the other hand, if the water level is not equal to or higher than the first level (S2: NO), the control device 30 turns off (stops) the cooling water pump P (S3).

[0031] Thereafter, the control device 30 judges whether the water level is equal to or higher than the second level (S4). If the water level is not equal to or higher than the second level (S4: NO), this process is repeated until the water level becomes equal to or higher than the second level.

[0032] If the water level is equal to or higher than the second level (S4: YES), the control device 30 judges whether the number of times the water level has fallen below the first level is equal to or higher than a predetermined number of times (S5). That is, the control device 30 judges whether the number of times the cooling water pump P has stopped is equal to or higher than a predetermined number of times. In addition, in step S5, the control device 30 may judge whether the number of times the water level has fallen to or higher than the second level, i.e., the number of times the cooling water pump P has started to operate is equal to or higher than a predetermined number of times. Furthermore, in step S5, the control device 30 may judge whether the number of times the water level has fallen below the first level during a certain time (unit time) is equal to or higher than a predetermined number of times. Similarly, the control device 30 may judge whether the number of times the water level has fallen to or higher than the second level during a certain time is equal to or higher than a predetermined number of times.

[0033] If the number of times the water level has fallen below the first level is not equal to or greater than the predetermined number (S5: NO), the process proceeds to step S2. On the other hand, if the number of times the water level has fallen below the first level is equal to or greater than the predetermined number (S5: YES), the control device 30 opens the control valve 27a (S6). That is, the control device 30 starts the supply of water from the second water supply pipe 27.

[0034] Next, the control device 30 turns on the cooling water pump P (S7). After that, the control device 30 judges whether a predetermined time has continuously elapsed since the water level became equal to or higher than the first level (S8). If the predetermined time has not continuously elapsed since the water level became equal to or higher than the first level (S8: NO), the process proceeds to step S2.

[0035] On the other hand, if a predetermined time has passed continuously since the water level reached or exceeded the first level (S8: YES), the control device 30 determines that a certain amount or more of cooling water is returning from the absorption chiller 10 because the water level has not decreased. In other words, the control device 30 determines that water filling is complete.

[0036] As a result, the control device 30 closes the control valve 27a to close the second water supply pipe 27 (S9), and turns off the cooling water pump P (S10). Then, the process shown in FIG.

[0037] In this way, according to the absorption refrigeration system 1 of this embodiment, when the number of stops of the cooling water pump P reaches or exceeds a predetermined number, cooling water is sent into the lower water tank 23 through the second water supply pipe 27. Therefore, cooling water is supplied to the lower water tank 23 not only from the water supply pipe 24 but also from the second water supply pipe 27. As a result, the water level in the lower water tank 23 is less likely to drop and become less likely to fall below the first level, and therefore the cooling water pump P is less likely to stop. Therefore, it is possible to provide an absorption refrigeration system 1 that can suppress the number of starts and stops of the cooling water pump P, and thereby suppress an increase in power consumption and a shortened life of the pump.

[0038] In addition, the amount of cooling water flowing into the lower water tank 23 per unit time through the water supply pipe 24 and the second water supply pipe 27 is set to be equal to or less than the amount of cooling water discharged per unit time through the overflow pipe 28. For this reason, for example, in the case where an abnormality occurs in the float valve 25, even if cooling water continues to be supplied into the lower water tank 23 through the water supply pipe 24 and the second water supply pipe 27, the cooling water can be discharged through the overflow pipe 28. This makes it possible to prevent the cooling water from overflowing from the lower water tank 23, and appropriately suppress the number of times the cooling water pump P is started and stopped while preventing leakage of the cooling water.

[0039] Next, a second embodiment of the present invention will be described. The absorption refrigeration system according to the second embodiment is similar to that of the first embodiment, but some configurations and processing contents are different from those of the first embodiment. In the following description of the second embodiment, elements that are the same as or similar to those of the first embodiment will be given the same reference numerals and descriptions thereof will be omitted.

[0040] Fig. 4 is a configuration diagram showing the vicinity of the lower water tank 23 of the cooling tower 20 according to the second embodiment. As shown in Fig. 4, the cooling water pump P is provided with an inverter I. In the second embodiment, the control device 30 is configured to control the rotation speed of the cooling water pump P by controlling the frequency of the inverter I. This enables the control device 30 to control the amount of cooling water pumped by the cooling water pump P per unit time.

[0041] Furthermore, in the second embodiment, when the number of times that the water level falls below the first level reaches or exceeds a predetermined number, as in the first embodiment, the control device 30 starts supplying water from the second water supply pipe 27 and reduces the operating frequency of the cooling water pump P. This reduces the amount of water pumped per unit time by the cooling water pump P, making it even more difficult for the cooling water pump P to start and stop repeatedly.

[0042] Fig. 5 is a flowchart showing the control of the control device 30 according to the second embodiment. The flowchart shown in Fig. 5 is also executed at the start of water filling. First, the control device 30 turns on the cooling water pump P (S1). After that, the control device 30 sets the frequency of the cooling water pump P to a first frequency (S11).

[0043] Next, through the processing of steps S2 to S4, the control device 30 judges whether the number of times the water level has fallen below the first level is equal to or greater than a predetermined number (S5). If the number of times the water level has fallen below the first level is equal to or greater than the predetermined number (S5: YES), the control device 30 opens the control valve 27a to start water supply from the second water supply pipe 27 (S6). Next, the control device 30 sets the frequency of the cooling water pump P to a second frequency lower than the first frequency (S12). This reduces the pumping amount of the cooling water pump P. Then, the processing proceeds to step S7.

[0044] Furthermore, if a predetermined continuous time has elapsed since the water level reached the first level or higher (S8: YES), the controller 30 determines that water filling is complete. The controller 30 then closes the control valve 27a to close the second water supply pipe 27 (S9), returns the frequency setting of the cooling water pump P to the first frequency (S13), and turns off the cooling water pump P (S10). Thereafter, the process shown in FIG. 5 ends.

[0045] In this way, according to the absorption refrigeration system 1 of the second embodiment, it is possible to provide an absorption refrigeration system 1 capable of suppressing an increase in power consumption and a shortened life of the pump, as in the first embodiment. Also, it is possible to appropriately suppress the number of starts and stops of the cooling water pump P while preventing leakage of the cooling water.

[0046] Furthermore, according to the second embodiment, when the number of times the cooling water pump P stops or starts operation reaches or exceeds a predetermined number, the amount of water pumped per unit time by the cooling water pump P is reduced. This makes it easier for the lower water tank 23 to continue to be filled with cooling water, and the number of times the cooling water pump P starts and stops can be appropriately suppressed.

[0047] The present invention has been described above based on the embodiments, but the present invention is not limited to the above embodiments, and modifications may be made without departing from the spirit of the present invention. The embodiments may be combined with each other or with other well-known or publicly known technologies as appropriate to the extent possible.

[0048] For example, in the first embodiment, it was described that it is preferable to satisfy the condition: (amount pumped by the cooling water pump P per unit time)≦(amount of cooling water flowing into the lower water tank 23 per unit time through the water supply pipe 24 and the second water supply pipe 27)≦(amount obtained by adding the amount discharged per unit time through the overflow pipe 28 to the above-mentioned pumped amount). In this regard, in the second embodiment, since the "amount pumped by the cooling water pump P per unit time" changes, it is preferable to satisfy the above condition both before and after the change. This is because it is possible to realize appropriate discharge of cooling water through the overflow pipe 28 both before and after changing the operating frequency of the cooling water pump P. [Explanation of symbols]

[0049] 1: Absorption refrigeration system 10: Absorption chiller 11: Water flow section 20: Cooling tower 23: Lower tank (tank) 24: Water supply pipe 25: Float valve 26: Water level sensor 27: Second water supply pipe 28: Overflow piping 30: Control device (control means) P: Cooling water pump (pump)

Claims

1. An absorption refrigeration system comprising: an absorption chiller; a cooling tower which supplies cooling water to a water passage section of the absorption chiller; and a pump which serves as a power source for sending cooling water in a water tank provided in the cooling tower to the absorption chiller, the absorption refrigeration system performing water filling to fill the water passage section with cooling water from a state in which the water passage section is not filled with cooling water, A water supply pipe for supplying cooling water to the water tank; a float valve that opens the water supply pipe to take in cooling water when the water level of the water tank is equal to or lower than a predetermined level, and closes the water supply pipe to prevent the cooling water from flowing into the water tank when the water level of the water tank exceeds the predetermined level; a water level sensor for detecting the water level of the water tank; a control means for stopping the pump when the water level detected by the water level sensor is lower than a first level, and for starting the operation of the pump when the water level detected by the water level sensor is equal to or higher than a second level that is higher than the first level; a second water supply pipe provided separately from the water supply pipe for supplying cooling water to the water tank; The control means sends cooling water into the water tank through the second water supply pipe when the number of times the pump is stopped or started reaches a predetermined number or more. An absorption refrigeration system.

2. an overflow pipe for discharging the cooling water when the water level of the water tank reaches a third level that is higher than the second level; The amount of cooling water discharged from the overflow pipe per unit time is set to be equal to or greater than the amount of cooling water flowing into the water tank per unit time through the water supply pipe and the second water supply pipe.

2. The absorption refrigeration system according to claim 1 .

3. The control means reduces the amount of water pumped by the pump per unit time when the number of times the pump stops or starts operation becomes equal to or greater than the predetermined number.

2. The absorption refrigeration system according to claim 1 .

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