Absorption type refrigerator system

Abstract

To provide an absorption type refrigerator system capable of controlling the number of a plurality of absorption type refrigerators to be driven and a cold water flow rate and capable of performing an efficient operation.SOLUTION: An absorption type refrigerator system comprises a plurality of absorption type refrigerators each of which comprises a high-temperature regenerator, a low-temperature refrigerator, an evaporator, a condenser, and an absorber, and each of which is constituted of circulation paths for an absorbent and a refrigerant respectively formed by connecting the components stated above. Each of the absorption type refrigerators includes: a cold water pipe passing through inside the evaporator; and a cold water pump adjusting a flow rate of the cold water flowing through the cold water pipe. Each of the absorption type refrigerators includes a control unit. Each of the control units is configured to be communicable with each other. Each of the control units acquires a refrigeration load, controls the flow rate of the cold water by a cold water pump according to the refrigeration load, and also controls the number of the absorption type refrigerators to be driven.SELECTED DRAWING: Figure 3

Description

[Technical Field]

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

[0002] Patent Document 1 discloses a technology that includes a plurality of absorption chillers, a chilled / hot water pump that delivers chilled / hot water generated by these absorption chillers to a load, and a centralized control device that centrally manages the control of these absorption chillers, and that starts and stops the absorption chillers so that the temperature of the chilled / hot water reaches a target temperature in response to an increase or decrease in the load supplied using the chilled / hot water flowing out of the absorption chillers as a heat source, thereby increasing or decreasing the number of operating units. Patent Document 2 discloses an absorption chiller that controls the discharge flow rate of a chilled water pump that delivers chilled water according to the rate of heat generated by a heating device. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-255880 [Patent Document 2] Japanese Patent Application Publication No. 04-080567 Summary of the Invention [Problem to be solved by the invention]

[0004] The present disclosure provides an absorption chiller system that can control the number of multiple absorption chillers to be driven and the flow rate of chilled water, thereby enabling efficient operation. [Means for solving the problem]

[0005] In order to achieve the above-mentioned object, the absorption chiller system of the present disclosure comprises a plurality of absorption chillers each comprising a high-temperature regenerator, a low-temperature regenerator, an evaporator, a condenser, and an absorber, which are connected by piping to form circulation paths for absorption liquid and refrigerant, and each of the absorption chillers comprises a chilled water pipe that passes through the inside of the evaporator, and a chilled water pump that adjusts the flow rate of chilled water flowing through the chilled water pipe, and each of the absorption chillers comprises a control unit, and the control units are configured to be able to communicate with each other, and each control unit obtains a cooling load and controls the flow rate of chilled water by the chilled water pump according to the cooling load, and also controls the number of absorption chillers being driven. [Effects of the Invention]

[0006] According to the present disclosure, it is possible to control both the number of absorption chillers to be driven and the flow rate of chilled water, thereby enabling efficient operation. [Brief explanation of the drawings]

[0007] [Figure 1] Schematic configuration diagram of an absorption chiller according to embodiment 1 [Figure 2] Block diagram showing a control configuration of the first embodiment [Figure 3] 1 is a timing chart showing an example of operation of an absorption chiller according to a cooling load ratio according to the first embodiment. [Figure 4] 1 is a flowchart showing an operation when the number of absorption chillers to be driven is changed in the first embodiment. [Figure 5] 1 is a flowchart showing an operation when flow rate control is performed in the absorption chiller according to the first embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0008] (Knowledge, etc. that formed the basis of the invention) At the time when the inventors arrived at the present disclosure, there was a technology in place that started and stopped a plurality of absorption chillers in response to an increase or decrease in the load of supply using chilled or hot water flowing out of the absorption chillers as a heat source, thereby increasing or decreasing the number of operating units, so that the temperature of the chilled or hot water would reach a target temperature. On the other hand, there was a technology in place that controlled the discharge flow rate of a chilled water pump that delivered chilled water in response to the proportion of the amount of heat heated by a heating device. However, in such absorption chillers, the control of the number of absorption chillers to be driven and the control of the flow rate by the chilled water pump are performed separately, and no system exists that performs both controls simultaneously. Therefore, a problem was discovered that the entire absorption chiller system in which multiple units are installed could not be operated efficiently, and the subject of the present disclosure was formed in order to solve this problem. Therefore, the present disclosure provides an absorption chiller system that can control the number of absorption chillers to be driven and the flow rate of chilled water, thereby enabling efficient operation.

[0009] Hereinafter, embodiments will be described in detail with reference to the drawings. However, unnecessary detailed description may be omitted. For example, detailed description of well-known matters or redundant description of substantially the same configuration may be omitted. This is to avoid unnecessary redundancy in the following description and to facilitate understanding by those skilled in the art. The accompanying drawings and the following description are provided to enable those skilled in the art to fully understand the present disclosure, and are not intended to limit the subject matter described in the claims.

[0010] (Embodiment 1) Hereinafter, the first embodiment will be described with reference to the drawings. [1-1.Configuration] [1-1-1. Configuration of absorption chiller] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. 1 is a schematic diagram of an absorption chiller according to this embodiment. The absorption chiller 100 uses water as a refrigerant and an aqueous solution of lithium bromide (LiBr) as an absorbing liquid.

[0011] As shown in FIG. 1, the absorption chiller 100 comprises an evaporator 1, an absorber 2 arranged in parallel with the evaporator 1, an evaporator-absorber shell 3 housing the evaporator 1 and absorber 2, a high-temperature regenerator 5 equipped with a gas burner (heating means) 4, a low-temperature regenerator 6, a condenser 7 arranged in parallel with the low-temperature regenerator 6, and a low-temperature regenerator condenser shell 8 housing the low-temperature regenerator 6 and condenser 7. The absorption chiller 100 also includes a low-temperature heat exchanger 12, a high-temperature heat exchanger 13, a refrigerant drain heat recovery device 17, a dilute absorbent pump 45, a concentrated absorbent pump 47, and a refrigerant pump 48, and these devices are connected by piping via absorbent pipes 21-25 and refrigerant pipes 31-35, etc., to form a circulation path.

[0012] The evaporator 1 is provided with a cold water pipe 14 for circulating and supplying the brine that has exchanged heat with the refrigerant in the evaporator 1 to a heat load (e.g., an air conditioning device) not shown, and a heat transfer pipe 14A formed as part of this cold water pipe 14 is arranged inside the evaporator 1. The absorber 2 and the condenser 7 are provided with cooling water pipes 15 for circulating cooling water sequentially through the absorber 2 and the condenser 7, and heat transfer pipes 15A and 15B formed in parts of the cooling water pipe 15 are disposed in the absorber 2 and the condenser 7, respectively.

[0013] The absorber 2 has the function of absorbing the refrigerant vapor evaporated in the evaporator 1 into an absorbing liquid and maintaining the pressure inside the evaporator-absorber shell 3 at a high vacuum state. A dilute absorbent liquid reservoir 2A is formed in the lower part of the absorber 2 to store dilute absorbent liquid that has absorbed the refrigerant vapor. One end of a dilute absorbent liquid pipe 21 having a dilute absorbent liquid pump 45 is connected to the dilute absorbent liquid reservoir 2A. The dilute absorbent liquid pipe 21 is provided with a branch dilute absorbent liquid pipe 21A that branches off downstream of the dilute absorbent liquid pump 45. This branched dilute absorbent liquid pipe 21A passes through the refrigerant drain heat recovery device 17 and then merges with the dilute absorbent liquid pipe 21 again downstream of the low-temperature heat exchanger 12. The other end of this dilute absorbent liquid pipe 21 passes through the high-temperature heat exchanger 13 and then opens into the gas layer section 5B located above the heat exchange section 5A formed in the high-temperature generator 5. The dilute absorbent pipe 21 branches into a second branch pipe 21B downstream of the low-temperature heat exchanger 12, and the second branch pipe 21B opens into the low-temperature generator 6.

[0014] The high-temperature regenerator 5 is configured by accommodating a gas burner 4 within a shell 60, and a heat exchanger 5A is formed above the gas burner 4, which heats and regenerates the absorbing solution using the flame of the gas burner 4 as a heat source. An exhaust path 40 through which exhaust gas burned by the gas burner 4 flows is connected to the heat exchanger 5A, and an exhaust gas heat exchanger 41 is provided in the exhaust path 40. In addition, a gas pipe 61 through which fuel gas is supplied and an intake pipe 63 through which air from a blower 62 is supplied are connected to the gas burner 4, and the gas pipe 61 and the intake pipe 63 are provided with control valves 64 for controlling the amounts of fuel gas and air.

[0015] An intermediate absorption liquid reservoir 5C is formed on the side of the heat exchange section 5A, in which the intermediate absorption liquid that has been thermally regenerated in the heat exchange section 5A and then flows out of the heat exchange section 5A accumulates. One end of a second intermediate absorption liquid pipe 23 is connected to the lower end of the intermediate absorption liquid reservoir 5C, and a high-temperature heat exchanger 13 is provided on the second intermediate absorption liquid pipe 23. The high-temperature heat exchanger 13 heats the absorption liquid flowing through the first intermediate absorption liquid pipe 22 with the heat of the high-temperature intermediate absorption liquid that has flowed out of the intermediate absorption liquid reservoir 5C, thereby reducing the fuel consumption of the gas burner 4 in the high-temperature regenerator 5. The other end of the second intermediate absorption liquid pipe 23 is connected to a strong absorption liquid pipe 25 that connects the low-temperature regenerator 6 and the absorber 2. The upstream side of the high-temperature heat exchanger 13 of the second intermediate absorption liquid pipe 23 is connected to the absorber 2 by an absorption liquid pipe 24 having an on-off valve V1 interposed therebetween.

[0016] The low-temperature regenerator 6 uses the refrigerant vapor separated in the high-temperature regenerator 5 as a heat source to heat and regenerate the absorption liquid accumulated in an absorption liquid reservoir 6A formed in the low-temperature regenerator 6, and a heat transfer tube 31A formed as part of a refrigerant pipe 31 extending from the upper end of the high-temperature regenerator 5 to the bottom of the low-temperature regenerator 6 is disposed in the absorption liquid reservoir 6A. By circulating the refrigerant vapor through this refrigerant pipe 31, the heat of the refrigerant vapor is transferred via the heat transfer tube 31A to the absorption liquid accumulated in the absorption liquid reservoir 6A, and the absorption liquid is further concentrated. One end of a concentrated absorption liquid pipe 25 is connected to the absorption liquid reservoir 6A of the low-temperature regenerator 6, and the other end of this concentrated absorption liquid pipe 25 is connected to a concentrated liquid sprayer 2C provided above the gas layer section 2B of the absorber 2. The concentrated absorption liquid pipe 25 is provided with a concentrated absorption liquid pump 47 and a low-temperature heat exchanger 12. This low-temperature heat exchanger 12 heats the dilute absorption liquid flowing through the dilute absorption liquid pipe 21 with the heat of the concentrated absorption liquid flowing out from the absorption liquid reservoir 6B of the low-temperature regenerator 6.

[0017] The concentrated absorbent pipe 25 is provided with a concentrated absorbent pump 47 and a bypass pipe 27 that bypasses the low-temperature heat exchanger 12 . When the operation of the concentrated absorbent pump 47 stops, the absorbent accumulated in the absorbent reservoir 6A of the low-temperature regenerator 6 is supplied into the absorber 2 through the concentrated absorbent pipe 25 and the bypass pipe 27.

[0018] As described above, the gas layer 5B of the high-temperature generator 5 and the refrigerant liquid reservoir 7A formed at the bottom of the condenser 7 are connected by the refrigerant pipe 31. This refrigerant pipe 31 includes a heat transfer pipe 31A that is piped to the absorption liquid reservoir 6A of the low-temperature generator 6 and a refrigerant drain heat recovery device 17, and the upstream side of the heat transfer pipe 31A of this refrigerant pipe 31 is connected to the gas layer 2B of the absorber 2 by a refrigerant pipe 32 that has an on-off valve V2 interposed therebetween. In addition, one end of a refrigerant pipe 34 through which the refrigerant flowing out from the refrigerant liquid reservoir 7A of the condenser 7 flows is connected to the refrigerant liquid reservoir 7A, and the other end of the refrigerant pipe 34 is connected to the gas space portion 1A of the evaporator 1 via a downwardly curved U-seal portion 34A. A refrigerant liquid reservoir 1B is formed below the evaporator 1 in which liquefied refrigerant accumulates, and this refrigerant liquid reservoir 1B and a sprayer 1C arranged above the gas layer portion 1A of the evaporator 1 are connected by a refrigerant pipe 35 with a refrigerant pump 48 interposed therebetween.

[0019] The cold water pipe 14 is also provided with a cold water pump 36 for adjusting the flow rate of the cold water. The cold water pipe 14 is provided with a cold water inlet temperature sensor 37 that detects the temperature of the cold water flowing through the cold water pipe 14 on the inlet side, and a cold water outlet temperature sensor 38 that detects the temperature of the cold water on the outlet side. The cold water pipe is also provided with a differential pressure sensor 39 that detects the differential pressure between the inlet and outlet sides of the cold water.

[0020] The absorption chiller 100 of this embodiment is also equipped with a gas extraction device 70, which in turn is equipped with a tank 71. An extraction pipe 52 communicating with the gas layer section 2B of the absorber 2 is connected to the top of the tank 71. A return pipe 73 communicating with the bottom of the absorber 2 is connected to the bottom of the tank 71. Furthermore, an absorption liquid pipe 75 connected to the dilute absorption liquid pipe 21 via an ejector pump 74 is connected to the top of the tank 71. Then, by driving the ejector pump 74, the dilute absorbing liquid in the dilute absorbing liquid pipe 21 is taken into the tank 71 via the absorbing liquid pipe 75. The dilute absorbing liquid flowing in through the absorbing liquid pipe 75 creates a negative pressure inside the tank 71, and as a result, not only the non-condensable gas stored in the upper part of the absorber 2 but also the refrigerant vapor, the vaporized absorbing liquid, and the like are guided to the top of the tank 51 through the extraction pipe 72.

[0021] Of the gas introduced into tank 71, the refrigerant vapor and vaporized absorption liquid dissolve in and are absorbed by the absorption liquid accumulated in the lower part of tank 71, but the non-condensable gas cannot dissolve in the absorption liquid and is therefore accumulated in the upper part of tank 71. The absorption liquid accumulated in the lower part of tank 71 is returned to the absorber 3 through return pipe 73.

[0022] [1-1-2. Control configuration] Next, the control configuration of this embodiment will be described. FIG. 2 is a block diagram showing the control configuration of this embodiment. As shown in FIG. 2, in this embodiment, a plurality of absorption chiller 100 (five in this embodiment) are installed. One of the absorption chillers 100 functions as a parent unit, and the other absorption chillers 100 function as child units. Each absorption chiller 100 is configured to be able to communicate, and the absorption chiller 100 functioning as the parent unit manages the operating time of each absorption chiller 100 and determines the number of absorption chillers 100 to be operated depending on the operating time of each absorption chiller 100 and the cooling load of each absorption chiller 100.

[0023] Next, a detailed description will be given of the control configuration of the absorption chiller 100. Since the control configuration of the absorption chiller 100 functioning as a parent unit or a child unit is the same, only the control configuration of the absorption chiller 100 functioning as a parent unit will be described in Fig. 2. The absorption chiller 100 is equipped with a control unit 50. The control unit 50 centrally controls each unit of the absorption chiller 100, and includes a CPU as an arithmetic execution unit, memories such as ROM and RAM that non-volatilely store basic control programs executable by the CPU, predetermined data, and other peripheral circuits. The control unit 50 is also configured so that detection signals from the chilled water inlet temperature sensor 37, the chilled water outlet temperature sensor 38, and the differential pressure sensor 39 are inputted thereto.

[0024] The control unit 50 is configured to control the fuel control valve 64 of the gas burner 4 of the absorption chiller 100 to thereby control combustion by the gas burner 4, and also to control the drive of the dilute absorbent pump 45, the concentrated absorbent pump 47, and the refrigerant pump 48. Furthermore, the control unit 50 is configured to control the inverters of the dilute absorbent pump 45, the concentrated absorbent pump 47, and the refrigerant pump 48 to thereby control the flow rates of the dilute absorbent pump 45, the intermediate absorbent pump 46, the concentrated absorbent pump 47, and the refrigerant pump 48. Furthermore, the control unit 50 is configured to control the opening and closing of each of the valves 28, V1, and V2.

[0025] The control unit 50 is configured to obtain the cooling load based on the detection signals of the chilled water inlet temperature sensor 37, the chilled water outlet temperature sensor 38, and the differential pressure sensor 39, and the like. The control unit 50 controls the flow rate of the chilled water pump 36 in accordance with the cooling load. The cooling load is calculated using the following formula: Cooling load = chilled water inlet / outlet temperature difference ÷ rated chilled water inlet / outlet temperature difference × chilled water flow rate (%) measured by differential pressure sensor 39

[0026] Here, when the cooling load is 50% or more, the control unit 50 controls the flow rate of the chilled water pump 36 in accordance with the cooling load. When the cooling load is less than 50%, the control unit 50 controls the flow rate of the chilled water pump 36 to 50%. The flow rate of the chilled water pump 36 is controlled to 50% when the cooling load is less than 50% because the flow rate cannot be controlled to 50% or less due to the specifications of the chilled water pump 36. However, if the chilled water pump 36 can control the flow rate to 50% or less, it is also possible to control the chilled water pump 36 according to the cooling load.

[0027] In this embodiment, the control unit 50 of the absorption chiller 100 functioning as the master unit manages the driving times of all the absorption chillers 100 . On the other hand, the control units 50 of the absorption chiller units 100 functioning as slave units transmit the cooling loads they have acquired to the control unit 50 of the absorption chiller unit 100 functioning as the master unit, and the control unit 50 of the absorption chiller unit 100 functioning as the master unit determines the cooling load of the entire absorption chiller system.

[0028] The control unit 50 of the absorption chiller unit 100 functioning as the parent unit determines the number of absorption chillers 100 to be driven depending on the driving time of each absorption chiller unit 100 and the cooling load of the entire absorption chiller system. In this case, for example, when it is decided to drive one absorption chiller 100 out of five absorption chillers 100, the absorption chiller 100 with the shortest drive time is driven. Then, when the cooling load increases and the second and subsequent absorption chillers 100 are driven, the drive starts from the absorption chiller 100 with the shortest drive time. This makes it possible to average the drive time of each absorption chiller 100.

[0029] When the control unit 50 of the absorption chiller 100 functioning as the parent unit starts driving the absorption chiller 100, it drives all the absorption chillers 100 and controls the chilled water pump 36 to operate at full speed (100% flow rate). This is to stabilize the operation of the absorption chiller 100. In the control of the absorption chillers at start-up, instead of driving all of them, any desired absorption chillers may be driven. Also, regarding the flow rate control by the chilled water pump, instead of operating at 100% flow rate, the pump may be operated at any desired opening.

[0030] After a predetermined time (e.g., 30 minutes) has elapsed since the absorption chiller 100 started operating, the control unit 50 of the absorption chiller 100 functioning as the master unit controls the number of absorption chillers 100 to be driven based on the cooling load of the entire system. Meanwhile, the control unit 50 controls the chilled water pump 36 according to the cooling load acquired by each absorption chiller 100. In this embodiment, when the number of absorption chiller units 100 being driven is changed, flow rate control by the chilled water pump 36 is not performed until a predetermined time has elapsed. The predetermined time is, for example, about 10 minutes when the number of driving units is increased, and about 30 minutes when the number of driving units is decreased. Note that this predetermined time can be set arbitrarily depending on the environment of the absorption chiller system, etc.

[0031] The reason why the flow rate control by the chilled water pump 36 is not performed until a predetermined time has elapsed is that the absorption chiller system may not be stable immediately after changing the number of absorption chiller units 100 being driven. If the flow rate control by the chilled water pump 36 is performed in this state, the cooling load obtained will also not be stable, and it is thought that there is a possibility that the number of units being driven will not be controlled appropriately. Furthermore, the reason why the specified time when the number of driving absorption chillers 100 is increased is set shorter than when the number of driving absorption chillers 100 is decreased is that when control is performed to increase the number of driving absorption chillers 100, the cooling capacity of the entire absorption chiller system is insufficient, and therefore, with an emphasis on user comfort, it is necessary to make the flow rate control by the chilled water pump 36 effective as soon as possible.

[0032] FIG. 3 is a timing chart showing an example of the operation of the five absorption chiller units 100 according to the ratio of the cooling load. As shown in FIG. 3, for example, first, one absorption chiller 100 is driven, and as the cooling load gradually increases, the other absorption chillers 100 are driven sequentially. When determining the number of absorption chillers 100 to be driven in accordance with the cooling load of the entire system, by determining in advance a threshold value for the number of absorption chillers 100 to be driven in accordance with the cooling load as shown in FIG. 3, the number of absorption chillers 100 to be driven in accordance with the cooling load of the entire system can be easily determined.

[0033] As described above, when the cooling load is 50% or more, the flow rate of the chilled water pump 36 is controlled according to the cooling load. When the cooling load is reduced, the operation of some of the absorption chillers 100 is stopped to control the number of absorption chillers 100 being driven, and the flow rate of the chilled water pump 36 is controlled according to the cooling load. As described above, in this embodiment, by performing control in accordance with the number of absorption chillers 100 to be driven and the cooling load, it is possible to obtain an efficient absorption chiller system.

[0034] [1-2. Operation] Next, the operation of this embodiment will be described. During cooling operation such as air conditioning, brine (e.g., chilled water) is circulated and supplied to a heat load (not shown) through the chilled water pipe 14. The control unit 50 controls the amount of heat input to the absorption chiller 100 so that the outlet temperature of the brine evaporator 1 (the temperature detected by the chilled water outlet temperature sensor 38) becomes a predetermined set temperature, for example, 7°C. Specifically, the control unit 50 starts all pumps 45, 47, and 48 and controls the combustion of gas in the gas burner 4, thereby controlling the heat of the gas burner 4 so that the temperature of the brine measured by the cold water outlet temperature sensor 38 becomes the predetermined 7°C.

[0035] In this case, the dilute absorbent from the absorber 2 is heated by the dilute absorbent pump 45 via the dilute absorbent pipe 21 through the low-temperature heat exchanger 12 and the high-temperature heat exchanger 13 or the exhaust gas heat exchanger 41 and sent to the high-temperature regenerator 5. The absorption liquid sent to the high-temperature regenerator 5 is heated in the high-temperature regenerator 5 by the flame from the gas burner 4 and the high-temperature combustion gas, causing the refrigerant in the absorption liquid to evaporate and separate. The intermediate absorption liquid, whose concentration has increased due to the refrigerant being evaporated and separated in the high-temperature regenerator 5, is sent to the concentrated absorption liquid pipe 25 via the high-temperature heat exchanger 13 and merges with the absorption liquid that has passed through the low-temperature regenerator 6.

[0036] On the other hand, the absorption liquid sent to the low-temperature regenerator 6 is heated by the high-temperature refrigerant vapor supplied from the high-temperature regenerator 5 through the refrigerant pipe 31 and flowing into the heat transfer pipe 31A, and the refrigerant is further separated, resulting in a further increase in concentration.This concentrated absorption liquid joins with the absorption liquid that has passed through the high-temperature regenerator 5, and is sent by the concentrated absorption liquid pump 47 to the absorber 2 via the low-temperature heat exchanger 12, and is sprayed from the concentrated liquid sprayer 2C.

[0037] The refrigerant separated and produced in the low-temperature regenerator 6 enters the condenser 7, where it condenses and accumulates in the refrigerant liquid reservoir 7A. When a large amount of refrigerant liquid accumulates in the refrigerant liquid reservoir 7A, the refrigerant liquid flows out of the refrigerant liquid reservoir 7A, passes through the refrigerant pipe 34, enters the evaporator 1, is pumped by the operation of the refrigerant pump 48, and is sprayed onto the heat transfer pipes 14A of the cold water pipes 14 from the sprayer 1C. The refrigerant liquid sprayed onto the heat transfer tubes 14A evaporates by taking heat of vaporization from the brine passing through the inside of the heat transfer tubes 14A, so that the brine passing through the inside of the heat transfer tubes 14A is cooled, and the cooled brine is supplied to the heat load from the chilled water pipes 14 to perform cooling operations such as air conditioning. The refrigerant evaporated in the evaporator 1 enters the absorber 2, where it is absorbed by the concentrated absorbing liquid supplied from the low-temperature regenerator 6 and sprayed from above, accumulates in the dilute absorbing liquid reservoir 2A of the absorber 2, and is transported to the high-temperature regenerator 5 by the dilute absorbing liquid pump 45, repeating this cycle.

[0038] Next, the control according to this embodiment will be described with reference to the flowcharts shown in FIGS. FIG. 4 is a flowchart showing the operation when the number of absorption chillers to be driven is changed in this embodiment. As shown in FIG. 4, in this embodiment, first, when the absorption chiller 100 is started (SA1), the control unit 50 of the absorption chiller 100 functioning as the parent unit determines whether 30 minutes have passed since the absorption chiller 100 was started (SA2). If it is determined that 30 minutes have not yet elapsed since the absorption chillers 100 were started (SA2: NO), all absorption chillers 100 are driven (SA7), and the chilled water pump 36 is controlled at 100% flow rate (SA8).

[0039] On the other hand, if it is determined that 30 minutes have passed since the absorption chiller 100 was started (SA2: YES), the control unit 50 of the absorption chiller 100 functioning as the parent unit acquires the cooling load from the control unit 50 of the absorption chiller 100 functioning as the child unit and determines the cooling load of the entire absorption chiller system (SA3). The control unit 50 determines whether or not the condition for changing the number of absorption chillers to be driven is met (SA4). If it is determined that the condition for changing the number of absorption chillers to be driven is met (SA4: YES), the control unit 50 changes the number of absorption chillers to be driven based on a preset threshold value for the number of absorption chillers to be driven relative to the cooling load of the entire system (SA5).

[0040] Thereafter, if the entire absorption chiller system has not stopped (SA6: NO), the control unit 50 repeats the operations of SA3 to SA5. If the entire absorption chiller system has stopped (SA6: YES), the control unit 50 ends the control.

[0041] FIG. 5 is a flowchart showing the operation when flow rate control is performed on the absorption chiller in this embodiment. As shown in Figure 5, before performing flow rate control, first, as in the case of Figure 4, when the absorption chiller 100 is started up (SB1), the control unit 50 of the absorption chiller 100 functioning as the parent unit determines whether 30 minutes have passed since the absorption chiller 100 was started up (SB2). If it is determined that 30 minutes have not yet elapsed since the absorption chillers 100 were started (SA2: NO), all absorption chillers 100 are driven (SB7) and the chilled water pump 36 is controlled at 100% flow rate (SB8).

[0042] On the other hand, if it is determined that 30 minutes have passed since the absorption chiller 100 was started (SB2: YES), the control unit 50 of each absorption chiller 100 acquires the cooling load of each absorption chiller 100 (SB3). The control unit 50 determines whether or not a prohibition condition for flow rate control is satisfied (SB4). In this embodiment, the prohibition condition for flow rate control is when the number of driven absorption chillers 100 is changed. When the control unit 50 determines that the conditions for prohibiting flow rate control of the absorption chiller are met (SB4: YES), the control unit 50 prohibits flow rate control by the chilled water pump 36 (SB9).

[0043] If the control unit 50 determines that the prohibition conditions for flow rate control of the absorption chiller are not met (SB4: NO), the control unit 50 of each absorption chiller 100 controls the flow rate using the chilled water pump 36 based on the respective cooling loads (SB5).

[0044] If the entire absorption chiller system is not stopped (SB6: NO), the control unit 50 repeats the operations SB3 to SB5 and SB9. If the entire absorption chiller system has stopped (SB6: YES), the control unit 50 ends the control.

[0045] [1-3. Effects, etc.] As described above, the absorption chiller system in the first embodiment includes a plurality of absorption chillers 100 each including a high-temperature regenerator 5, a low-temperature regenerator 6, an evaporator 1, a condenser 7, and an absorber 3, which are connected by pipes to form circulation paths for the absorption liquid and the refrigerant. Each absorption chiller 100 includes a chilled water pipe that passes through the inside of the evaporator, and a chilled water pump 36 that adjusts the flow rate of chilled water flowing through the chilled water pipe. Each absorption chiller 100 includes a control unit 50, and the control units 50 are configured to be able to communicate with each other. Each control unit 50 acquires a cooling load and controls the flow rate of chilled water from the chilled water pump 36 according to the cooling load, and also controls the number of absorption chillers 100 that are driven. This makes it possible to control both the number of absorption chillers 100 to be driven and the flow rate of chilled water, thereby enabling efficient operation.

[0046] Furthermore, in the absorption chiller system according to the first embodiment, when the number of absorption chillers 100 to be driven is changed, each control unit 50 does not control the flow rate by the chilled water pump 36 until a predetermined time has elapsed. According to this, when the number of absorption chillers 100 being driven is changed, the absorption chiller system may not be stable. Therefore, by not performing flow rate control by the chilled water pump 36 until a predetermined time has elapsed, the absorption chiller system can be operated stably.

[0047] In addition, in the absorption chiller system of embodiment 1, after changing the number of absorption chillers 100 to be driven, each control unit 50 controls the flow rate of the chilled water pump 36 in accordance with the acquired cooling load after a predetermined time has elapsed. According to this, when the number of absorption chillers 100 to be driven is changed, the absorption chiller system may not be stable. However, after a predetermined time has passed, the absorption chiller system will be stabilized, and efficient operation can be achieved by controlling the flow rate using the chilled water pump 36.

[0048] In addition, in the absorption chiller system of embodiment 1, each control unit 50 controls the flow rate of the chilled water pump 36 in accordance with the cooling load when the acquired cooling load is 50% or more, and controls the flow rate of the chilled water pump 36 to 50% when the acquired cooling load is less than 50%. This allows flow rate control by the chilled water pump 36 according to the cooling load, and even when using a chilled water pump 36 that cannot control the flow rate to 50% or less, efficient operation is possible.

[0049] In addition, in the absorption chiller system of embodiment 1, when each absorption chiller 100 is started, each control unit 50 operates all of the absorption chillers 100 until a predetermined time has elapsed, and controls the chilled water pump 36 to be fully open. According to this, when the absorption chiller 100 is started up, the operation of the absorption chiller 100 can be quickly stabilized.

[0050] In addition, in the absorption chiller system of embodiment 1, one of the absorption chillers 100 functions as a parent unit that manages the other absorption chillers 100, and the absorption chiller 100 functioning as the parent unit manages the operating time of each absorption chiller 100 and determines the number of absorption chillers 100 to be driven depending on the operating time of each absorption chiller 100 and the cooling load acquired by the control unit 50 of each absorption chiller 100. According to this, the control unit 50 of the absorption chiller unit 100 functioning as the parent unit manages the drive times of all the absorption chiller units 100, and the number of absorption chiller units 100 to be driven can be determined and controlled in accordance with the drive times and cooling load of the absorption chiller units 100. Therefore, the drive times of the absorption chiller units 100 can be averaged and the units can be driven efficiently.

[0051] (Other embodiments) As described above, the first embodiment has been described as an example of the technology disclosed in the present application. However, the technology in the present disclosure is not limited to this, and can be applied to embodiments in which modifications, substitutions, additions, omissions, etc. are made. Furthermore, it is also possible to combine the components described in the first embodiment above to create new embodiments.

[0052] The units shown in Figure 2 are merely examples, and the specific implementation form is not particularly limited. In other words, it is not necessary to implement hardware corresponding to each unit individually, and it is of course possible to configure the units so that the functions are realized by a single processor executing a program. Furthermore, some of the functions realized by software in the above-described embodiments may be implemented by hardware, or some of the functions realized by hardware may be implemented by software.

[0053] (Other embodiments) Note that the first embodiment has been described as an example of the technology disclosed in the present application. However, the technology in the present disclosure is not limited to this, and can be applied to embodiments in which modifications, substitutions, additions, omissions, etc. are made.

[0054] (Addendum) The above description of the embodiments discloses the following techniques.

[0055] (Technology 1) An absorption chiller system comprising a plurality of absorption chillers each comprising a high-temperature regenerator, a low-temperature regenerator, an evaporator, a condenser, and an absorber, which are connected by piping to form circulation paths for absorption liquid and refrigerant, and each of the absorption chillers comprises a chilled water pipe passing through the inside of the evaporator, and a chilled water pump that adjusts the flow rate of chilled water flowing through the chilled water pipe, and each of the absorption chillers comprises a control unit, and the control units are configured to be able to communicate with each other, and each control unit obtains a cooling load, and controls the flow rate of chilled water by the chilled water pump according to the cooling load, and also controls the number of absorption chillers being driven. This configuration makes it possible to control both the number of absorption chillers to be driven and the flow rate of chilled water, thereby enabling efficient operation.

[0056] (Technical 2) In the absorption chiller system according to Technical 1, when the number of driven absorption chillers is changed, each of the control units does not control the flow rate of the chilled water pump until a predetermined time has elapsed. With this configuration, if the number of driving absorption chillers is changed, the absorption chiller system may not be stable. Therefore, by not performing flow rate control using the chilled water pump until a predetermined time has elapsed, the absorption chiller system can be operated stably.

[0057] (Technology 3) In the absorption chiller system according to Technology 1 or Technology 2, after changing the number of driven absorption chillers, each of the control units controls the flow rate of the chilled water pump in accordance with the acquired cooling load after a predetermined time has elapsed. With this configuration, if the number of absorption chillers being driven is changed, the absorption chiller system may not be stable. However, after a predetermined time has passed, the absorption chiller system will stabilize, and efficient operation can be achieved by controlling the flow rate using the chilled water pump.

[0058] (Technology 4) The absorption chiller system according to any one of Technology 1 to Technology 3, wherein each of the control units controls the flow rate of the chilled water pump in accordance with the cooling load when the acquired cooling load is 50% or more, and controls the flow rate of the chilled water pump to 50% when the acquired cooling load is less than 50%. This configuration allows flow rate control by the chilled water pump according to the cooling load, and even when using a chilled water pump that cannot control the flow rate to 50% or less, efficient operation is possible.

[0059] (Technical 5) The absorption chiller system according to any one of Technical 1 to Technical 4, wherein each of the control units operates all of the absorption chillers and controls the chilled water pump to be fully open until a predetermined time has elapsed when each of the absorption chillers is started. With this configuration, the operation of the absorption chiller can be quickly stabilized when the absorption chiller is started up.

[0060] (Technology 6) An absorption chiller system according to any one of Technology 1 to Technology 5, wherein one of the absorption chillers functions as a parent unit that controls the other absorption chillers, and the absorption chiller functioning as the parent unit manages the operating time of each of the absorption chillers and determines the number of absorption chillers to be operated according to the operating time of each of the absorption chillers and the cooling load acquired by the control unit of each of the absorption chillers. With this configuration, the control unit of the absorption chiller unit that functions as the parent unit manages the operating times of all the absorption chillers, and the number of operating absorption chillers can be determined and controlled according to the operating times and cooling load of the absorption chillers. As a result, the operating times of the absorption chillers can be averaged and they can be operated efficiently. [Industrial Applicability]

[0061] INDUSTRIAL APPLICABILITY The present disclosure is suitably applicable to an absorption chiller system that can control the number of multiple absorption chillers to be driven and the flow rate of chilled water, thereby enabling efficient operation. [Explanation of symbols]

[0062] 1. Evaporator 2. Absorber 3. Absorber 4 Gas burner 5 High temperature regenerator 6 Low temperature regenerator 7. Condenser 12 Low temperature heat exchanger 13 High temperature heat exchanger 14 Cold water pipe 15 Cooling water pipe 17 Refrigerant drain heat recovery device 21 Rare absorbent liquid pipe 36 Chilled water pump 37 Chilled water inlet temperature sensor 38 Chilled water outlet temperature sensor 39 Differential pressure sensor 50 control section 100 Absorption chiller

Claims

1. a plurality of absorption chillers each including a high-temperature regenerator, a low-temperature regenerator, an evaporator, a condenser, and an absorber, which are connected by piping to form a circulation path for an absorption liquid and a refrigerant, each of the absorption chillers includes a chilled water pipe passing through the inside of the evaporator, and a chilled water pump that adjusts the flow rate of chilled water flowing through the chilled water pipe; Each of the absorption chillers includes a control unit, and the control units are configured to be able to communicate with each other, Each of the control units acquires a cooling load, and controls the flow rate of chilled water from a chilled water pump in accordance with the cooling load, and also controls the number of absorption chillers to be driven. Absorption chiller system.

2. When the number of the absorption chillers being driven is changed, each of the control units does not control the flow rate of the chilled water pump until a predetermined time has elapsed. The absorption chiller system according to claim 1 .

3. each of the control units controls the flow rate of the chilled water pump in accordance with the acquired cooling load after a predetermined time has elapsed after changing the number of the absorption chiller units to be driven; The absorption chiller system according to claim 2 .

4. When the acquired cooling load is 50% or more, each of the control units controls the flow rate of the chilled water pump according to the cooling load, and when the acquired cooling load is less than 50%, controls the flow rate of the chilled water pump to 50%. The absorption chiller system according to claim 3 .

5. When each of the absorption chillers is started, each of the control units operates all of the absorption chillers and controls the chilled water pumps to be fully open until a predetermined time has elapsed. The absorption chiller system according to claim 1 .

6. Among the absorption chillers, one of the absorption chillers functions as a master unit that controls the other absorption chillers, the absorption chiller unit functioning as the parent unit manages the driving time of each of the absorption chillers, and determines the number of the absorption chillers to be driven in accordance with the driving time of each of the absorption chillers and the cooling load acquired by the control unit of each of the absorption chillers. The absorption chiller system according to claim 1 .

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