JP5685782B2 - Chiller linked operation method and system - Google Patents

Description

  The present invention relates to a chiller connection operation method and system suitable for use in operation by connecting a plurality of chillers.

  Generally, as a method (apparatus) for connecting and operating a plurality of refrigeration apparatuses and chiller / hot water machines, a control apparatus for a refrigeration apparatus disclosed in Patent Document 1 and a connected chiller / heater disclosed in Patent Document 2 There are known methods for controlling the number of operating units.

  In the control device disclosed in Patent Document 1, a plurality of chilling units that perform a refrigeration operation for adjusting the conditioned liquid flowing through the liquid system to a predetermined temperature are connected to the liquid system, while the chilling unit during the refrigeration operation Based on the thermo-on state in which the compressor is driven and the thermo-off state in which the compressor is stopped, at each chilling operation of the chilling unit, a judgment value based on the thermo-on count of each chilling unit during the previous refrigeration operation While the chilling unit with the smallest is set as the master unit, the other chilling unit is set as the slave unit, and the master unit is preferentially controlled to the thermo-on state every time the operation is started, while the child with a small judgment value based on the number of thermo-ons Leveling means for sequentially starting from the machine is provided. In addition, the operation number control method disclosed in Patent Document 2 is a method for controlling the number of connected chilled water heaters having a plurality of chilled water heaters with a common chilled water hot water pipe. The number of chilled water or hot water outlet set temperature difference and the inlet temperature are used to calculate the optimum number of chilled water heaters, and by comparing the calculated number of chilled water heaters with the actual number of chilled water heaters The operation is to increase or decrease one machine at a time.

  By the way, the above-described method (apparatus) for connecting and operating a plurality of chillers is used for applications such as an air conditioner and a chiller / heater, so that a very precise control is not required. Therefore, it is relatively easy to simply connect a plurality of chillers in parallel and perform control to change the number of operating chillers according to the load factor or the like. However, in applications where precise cooling water needs to be supplied, cooling water with a constant flow rate is always required by highly accurate and stable temperature control. Therefore, as described in Patent Documents 1 and 2 described above. Such a requirement cannot be satisfied by a coupled operation using a simple parallel connection.

  For this reason, conventionally, a method (apparatus) that enables supply of precise cooling water using a plurality of chillers has also been proposed. Patent Document 3 discloses a discharge unit that requires high-precision temperature control and the discharge unit. A temperature control device for a gas laser device that adjusts the temperature of a plurality of laser devices having a power supply unit that requires temperature adjustment with a lower accuracy than a discharge unit and allows temperature adjustment at a higher temperature than a discharge unit. A chiller for generating a cooling water for adjusting the temperature of each discharge unit, a chiller for generating a cooling water for adjusting the temperature of each power supply unit, a pipe for connecting the chiller and each discharge unit in parallel, a chiller and each power supply A temperature control device for a gas laser device including a pipe that connects the parts in parallel is disclosed.

JP-A-10-122604 JP 2004-144457 A JP 2010-219516 A

  However, the conventional temperature control apparatus that operates the above-described plurality of chillers has the following problems.

  First, even if a plurality of chillers are used, it is a so-called connected operation for control, and cannot be said to be a connected operation on the machine (on the flow path). In the end, since multiple chillers are operated simultaneously and each chiller is controlled independently, the advantages of the original coupled operation, for example, flexible operation such as stopping some chillers due to a decrease in load factor, etc. Control cannot be performed. As a result, there is a limit in ensuring efficient operation of each chiller and energy saving from the viewpoint of the entire operation.

  Secondly, unlike the case of connecting the chillers in a simple parallel connection, as in the case of the chiller connection operation used in other fields where the precision is not required, such as the air conditioner described above, It is necessary to construct a corresponding dedicated system circuit, and it is not possible to flexibly handle various applications. Therefore, there are difficulties in adaptability and versatility, and there is a limit from the viewpoint of reducing costs.

  An object of the present invention is to provide a chiller connection operation method and system that solve the problems in the background art.

  In order to solve the above-described problem, the chiller connection operation method according to the present invention supplies the cooling liquid L accommodated in the cooling liquid tank 2 from the supply port 3s to the external cooled part M, and from the cooled part M. The coolant circulation system 4 that stores the coolant L after the heat exchange returned to the return port 3r in the coolant tank 2, the cooling device 5 that cools the coolant L supplied from the supply port 3s, and at least the cooling device 5 When a plurality of chillers C having a control system 6 that performs the above control are connected in parallel, the coolant tanks 2 in the chillers C are connected by a common pressure equalizing pipe 8 and each chiller C is connected. By connecting a centralized control device 7 having a computing function to the control system 6 of ..., the load factor X of each chiller C is monitored, and becomes equal to or less than the preset first monitoring load factor Xd. Then, one The chiller C is stopped except for the coolant supply function, and when the preset second monitoring load factor Xu is reached, control is performed to restore a part of the stopped chillers C. When stopping, the total control amount Dr of all chillers C during operation is divided into the number of chillers C except the chiller C to be stopped, and the control applied to each chiller C is performed, and the chiller stopped. When returning C, the total control amount Ca of all chillers C in operation is divided into the number of chillers C including the chiller C to be returned, and control is applied to each chiller C. To do.

  Further, in order to solve the above-described problem, the chiller connection operation system 1 according to the present invention supplies the cooling liquid L accommodated in the cooling liquid tank 2 from the supply port 3 s to the external cooled part M, and is also cooled. A coolant circulation system 4 for storing the coolant L after the heat exchange returned from the section M to the return port 3r in the coolant tank 2, a cooling device 5 for cooling the coolant L supplied from the supply port 3s, and at least When configuring a linked operation system in which a plurality of chillers C... Having a control system 6 that controls the cooling device 5 are connected in parallel, a connection is commonly made to the coolant tank 2 in each chiller C. The load factor X of each chiller C ... is monitored by connecting to the control system 6 ... of each chiller C ... with the pressure equalizing pipe 8, and if the load ratio Xd is lower than the preset first monitoring load factor Xd, Some chillers When the chiller C is stopped except for the cooling liquid supply function and the preset second monitoring load factor Xu is exceeded, a control is performed to restore a part of the stopped chillers C, while the chiller C is stopped. In addition, the total control amount Dr of all the chillers C in operation is divided into the number of chillers C except the chiller C to be stopped, and the control applied to each chiller C is performed, and the stopped chiller C is restored. When the control is performed, the total control amount Da of all the chillers C during operation is divided into the number of chillers C including the chiller C to be returned and the control applied to each chiller C is concentrated. A control device 7 is provided.

  On the other hand, according to a preferred embodiment of the present invention, when the load factor X is not increasing, the control of stopping the chiller C can be performed when the load factor X is not increasing. Moreover, when stopping the chiller C, it calculated | required with respect to each chiller C ... by feedforward control or [the sum total of the operation amount of the integral control in PID control before a stop] / [the number of chiller operation after a stop]. It is possible to perform control to change the operation amount of integral control. On the other hand, if the load factor Xu is equal to or higher than the second monitoring load factor Xu, the control of returning the chiller C can be performed on the condition that the load factor X is not decreasing. Further, when returning the chiller C, the rate of increase of the load factor X is obtained, and the number of chillers C to be returned can be determined based on this rate of increase. Further, when returning the chiller C, it is obtained by feedforward control or [total amount of integral control operation in PID control before return] / [number of chiller operation after return] for each chiller C. It is possible to perform control to change to the operation amount of integral control in PID control.

  According to such a chiller connection operation method and system 1 according to the present invention, the following remarkable effects can be obtained.

  (1) Even when a plurality of chillers C are connected in parallel to a cooled part M that requires a coolant L having a constant flow rate through stable temperature control with high accuracy, In addition to being able to sufficiently meet the requirements of the cooled part M, it is partly due to the reduction (or increase) in the merit of connecting operation by connecting a plurality of chillers in parallel, for example, the load factor X It is possible to perform flexible operation control such as stopping (or returning) the chiller C. As a result, each chiller C... Can be operated near the load factor X with the highest efficiency, and the unused chillers C.

  (2) Since the chillers C can be configured by simply connecting them in parallel, the number of chillers C to be connected can be easily changed (increased or decreased). As a result, it is possible to construct a linked operation system 1 excellent in adaptability and versatility, such as being able to flexibly cope with various uses, and also contributing to cost reduction of the entire system.

  (3) Since the connecting operation system 1 is provided with the pressure equalizing pipe 8 commonly connected to the coolant tank 2 in each chiller C ..., the liquid level of the coolant L accommodated in the coolant tank 2 ... of each chiller C ... Can be maintained at the same height. As a result, the variation in the relative flow rate of the coolant L and the variation in the cooling capacity (temperature control) between the chillers C can be eliminated, and the flow rate and temperature control can be further stabilized.

  (4) According to a preferred embodiment, if the control is performed to stop the chiller C on condition that the load factor X is not increasing when the first monitoring load factor Xd or less, the load factor X is Since the case where it becomes the 1st monitoring load factor Xd by temporary disturbance etc. can be excluded, useless number change of chillers C ... can be avoided and stability of the whole system 1 can be improved.

  (5) When the chiller C is stopped according to a preferred embodiment, if the feedforward control is performed on each chiller C, the current output (input) of the compressor provided in the cooling device 5 is forced. Therefore, it is possible to easily and surely implement by using a relatively general control method such as normal PID control (feedback control).

  (6) When the chiller C is stopped according to a preferred embodiment, for each chiller C..., It is obtained by [total operation amount of integral control in PID control before stop] / [number of chiller operation after stop]. If the control for changing the operation amount to the integral control is performed, the detection result from the existing temperature sensor that detects the temperature of the coolant L supplied from each chiller C. This can be easily implemented by using the operation amount of the control system 6 (control signal for the compressor provided in the cooling device 5).

  (7) If the second monitoring load factor Xu is equal to or higher than the second monitoring load factor Xu according to a preferred embodiment, the load factor X can be reduced by performing control for returning the chiller C on condition that the load factor X is not decreasing. Since the case where it becomes the 2nd monitoring load factor Xu etc. by temporary disturbance can be excluded, the useless number change of chillers C ... can be avoided and the stability of the whole system 1 can be improved.

  (8) When the chiller C is returned according to a preferred embodiment, the rate of increase of the load factor X is obtained, and the number of chillers C to be returned is determined based on this rate of increase. Since the optimum number of chillers C can be restored, even when the load suddenly increases due to some factor, it is possible to accurately cope with it.

  (9) When the chiller C is returned according to a preferred embodiment, the current output (input) of the compressor provided in the cooling device 5 is forced if feedforward control is performed on each chiller C. Therefore, it is possible to easily and surely implement by using a relatively general control method such as normal PID control (feedback control).

  (10) When returning the chiller C according to a preferred embodiment, for each of the chillers C..., The total amount of integral control operation amount in the PID control before the return / the number of chiller operations after the return is obtained. If the control to change to the operation amount of the integral control in the PID control is performed, in particular, no additional parts are required, and an existing temperature sensor that detects the temperature of the coolant L supplied from each chiller C. The detection result and the operation amount of the control system 6 (such as a control signal for the compressor provided in the cooling device 5) can be easily implemented.

The flowchart for demonstrating the process sequence of the connection driving | operation method which concerns on suitable embodiment of this invention, System diagram of a linked operation system according to a preferred embodiment of the present invention, A block diagram of a control system in the connected operation system; The front view which shows the internal structure of the chiller which comprises the connection driving | operation system, A side view including a part of the internal structure of the chiller constituting the connected operation system, System diagram of the chiller that constitutes the connected operation system, Temperature change data diagram showing change in coolant temperature with respect to time when using the same connected operation system,

  Next, preferred embodiments according to the present invention will be given and described in detail with reference to the drawings.

  First, the structure of the chiller C which comprises the connection operation system 1 which concerns on this embodiment is demonstrated with reference to FIGS.

  The illustrated chiller C is a free cooling chiller having a free cooling function that cools the coolant L using the outside air temperature when the outside air temperature decreases. In addition, the cooling liquid L illustrates the case where the cooling water Lw is used. As shown in FIGS. 4 and 5, the chiller C includes a cabinet 11 that is formed in a rectangular parallelepiped shape as a whole, and the upper interior of the cabinet 11 is configured as an outside air heat exchange chamber Rc, and the lower interior is defined as a storage chamber Ri. Configure. A blower fan 12 is disposed at the upper end of the cabinet 11.

  A condenser 13 and an outside air heat exchanger 14 are disposed inside the outside air heat exchange chamber Rc. In this case, as shown in FIG. 6, the condenser 13 constitutes an internal cooling system U1 including a cooling device 5 using a refrigeration cycle in which a refrigerant circulates, and the outside air heat exchanger 14 includes air cooling air (outside air ) An outside air cooling system U2 that performs heat exchange between A and the cooling water Lw is configured. The cooling device 5 (internal cooling system U1) and the outside air cooling system U2 both have a function of cooling the cooling water Lw described later. In particular, the outside air cooling system U2 has the above-described free cooling function that cools the cooling water Lw using the outside air temperature when the outside air temperature decreases.

  As shown in FIGS. 5 and 6, the outside air heat exchanger 14 is configured by a combination of a pair of flat heat exchange units 14 p and 14 q, and the inside of the outside air heat exchange chamber Rc is viewed from the side. It arrange | positions so that it may become a shape. Thus, the blower fan 12 is disposed above the internal space sandwiched between the inner surfaces of the two heat exchange units 14p and 14q, and is disposed at a downstream position in the blowing direction Fw. In addition, air inlets 11i and 11i are provided on the side surfaces (front and back) of the cabinet 11 facing the two heat exchange units 14p and 14q, and an exhaust port 11e is provided at the upper end of the cabinet 11 located above the blower fan 12. Is provided.

  The heat exchange unit 14p can be implemented in the form of a general heat exchanger in which a cooling liquid pipe through which the cooling water Lw passes is formed in a zigzag shape and a large number of heat radiation fins are attached to the outer peripheral surface. The heat exchange unit 14p is disposed upright (tilted) at a predetermined tilt angle (for example, around 15 °) with respect to the vertical line. The other heat exchange unit 14q is configured in the same manner as the heat exchange unit 14p, and is arranged to stand (tilt) at a predetermined tilt angle (for example, around 15 °) with respect to the vertical line. In this case, the inclination directions of the heat exchange units 14p and 14q are opposite directions. Thereby, as shown in FIG. 5, the outdoor air heat exchanger 14 which becomes V shape seeing from the side is obtained.

  On the other hand, the condenser 13 is also constituted by a combination of two condensing units 13p and 13q. The condensing unit 13p has a general condenser structure, that is, a structure in which a large number of heat-dissipating fins are attached to the outer peripheral surface of a refrigerant pipe unit in which refrigerant pipes through which refrigerant passes are formed in a zigzag shape. The other condensing unit 13q is configured similarly to the condensing unit 13p. And each condensation unit 13p, 13q is arrange | positioned so that it may each overlap with each heat exchange unit 14p, 14q from the downstream of the ventilation direction Fw of the ventilation fan 12, as shown in FIG. With such a configuration, the condenser 13 faces the outside air heat exchanger 14 from the downstream side in the air blowing direction Fw, so that there is no dead space when the condenser 13 and the outside air heat exchanger 14 are disposed. In addition to contributing to downsizing, the fan 12 can be easily shared. In addition, since the temperature of the outside air heat exchanger 14 is usually lower than the temperature of the condenser 13, more efficient heat exchange can be performed in consideration of the blowing direction Fw.

  Further, as shown in FIG. 4, the storage room Ri includes components of the refrigeration cycle in the internal cooling system U1 such as the compressor 17 excluding the condenser 13 and a circulation pump 18 excluding the outside air heat exchanger 14. Components in the outside air cooling system U2 are disposed. Further, a cooling liquid tank 2 for storing the cooling water Lw 2, a pumping pump 20 for sending the cooling water Lw of the cooling liquid tank 2 to the outside through the heat exchanger (cooling unit) 19 (FIG. 6) in the cooling device 5, and A control panel 21 on which electrical components such as an inverter are mounted is provided.

  On the other hand, FIG. 6 shows an entire system circuit of the chiller C. In the figure, U1 and U2 indicate the above-described internal cooling system and external air cooling system, respectively. In the internal cooling system U1, reference numeral 5 denotes a cooling device constituted by a refrigeration cycle, and the refrigerant inlet of the condenser 13 described above is connected to the outlet 19f on the primary side 19f of the heat exchanger (cooling unit) 19 via the compressor 17. At the same time, the inlet of the primary side 19 f is connected to the refrigerant outlet of the condenser 13 via the electronic expansion valve 22. Thereby, the well-known refrigeration cycle in which a refrigerant circulates is constituted, and cooling water Lw supplied to the outside from supply port 3s mentioned below can be cooled. In this case, a compressor inverter 17i is connected to the compressor 17, and the rotation speed of the compressor motor in the compressor 17 is variably controlled. Reference numeral 23 denotes a high pressure switch for the refrigerant.

  In addition, a coolant circulation system 4 that is connected to the secondary side 19s of the heat exchanger 19 and circulates the coolant Lw is provided. Thereby, heat exchange between the refrigerant and the cooling water Lw is performed using the heat exchanger 19. The coolant circulation system 4 connects the coolant inlet of the secondary side 19 s of the heat exchanger 19 to the tank supply port 2 i of the coolant tank 2 via the pressure feed pump 20, and also connects the secondary side of the heat exchanger 19. The coolant outlet of 19s is connected to a supply port 3s to which an external supply pipe Ps described later is connected, and the return port 3r to which an external return pipe Pr described later is connected is a tank return of the coolant tank 2. Connect to port 2r. As a result, the cooling water Lw stored in the cooling liquid tank 2 is supplied from the supply port 3s to the external cooled part M, and the heat exchanged cooling water Lw returned from the cooled part M to the return port 3r is supplied to the cooling liquid. A coolant circulation system 4 accommodated in the tank 2 is configured. The suction port of the pressure pump 20 also serves as the tank supply port 2i.

  The outside air cooling system U2 includes the outside air heat exchanger 14 described above, and the coolant inlet of the outside air heat exchanger 14 is connected to the tank supply port 2s of the coolant tank 2 via the circulation pump 18, and the outside air The coolant outlet of the heat exchanger 14 is connected to the tank return port 2b of the coolant tank 2 via a return pipe. Thus, a coolant circulation circuit 24 that circulates the coolant Lw accommodated in the coolant tank 2 to the outside air heat exchanger 14 is configured. In addition, 25 is a bypass valve, 26 is a tank drain valve, and 27 is a water pressure gauge.

  On the other hand, spray nozzles Ns..., Ns... Constituting the watering mechanism 31 are disposed in the vicinity of the intake ports 11i and 11i. Each of the spray nozzles Ns..., Ns... Is arranged toward the heat exchange units 14p and 14q so as to be sprayed obliquely upward, and an optimum position and angle are selected so that it can be diffused over a wider range. In the case of illustration, as shown in FIG. 4, two spray nozzles Ns, Ns... Spaced apart from each other are arranged for each heat exchange unit 14p, 14q. Each spray nozzle Ns... Is attached on the installation surface of each heat exchange unit 14p, 14q. Thereby, each spray nozzle Ns... Is arranged on the upstream side in the blowing direction Fw with respect to each heat exchange unit 14p, 14q, and is set at a predetermined angle with respect to the outer surface of each heat exchange unit 14p, 14q. (For example, around 30 [°]) can be sprayed. The spray position on the outer surface of the heat exchange units 14p, 14q is set to a position closer to the lower side than the center position. Furthermore, each spray nozzle Ns... Is connected to a water supply port 33 to which water Lwm is supplied via a water supply valve 32 as shown in FIG. A water supply source such as an external water pipe is connected to the water supply port 33. In this case, the water supply valve 32 may be an electromagnetic on-off valve that supplies or stops water Lwm to each spray nozzle Ns... Or a control valve that can variably control the amount of water Lwm supplied to each spray nozzle Ns. . In addition, in FIG. 6, 34 is a water pressure gauge, and 35 is an outside air temperature sensor.

  The chiller C includes a control system 6 that controls the temperature of the cooling water Lw by controlling at least the cooling device 5. The control system 6 includes a chiller controller 41 shown in FIG. FIG. 3 shows only the control system related to the control of the coupled operation system 1 according to the present embodiment. The chiller controller 41 has a computing function for performing various controls in the entire chiller C, and includes a controller main body 42 including hardware such as a CPU and various drive units. The controller main body 42 includes a memory 42m. The memory 42m has a program area 42mp for storing a temperature control of the cooling water Lw in the chiller C and a sequence control program for executing a series of operations, and setting data. It has a data area 42 md for writing various data including it. An operation unit 43 and a display unit 44 are attached to the controller main body 42, and the operation unit 43 and the display unit 44 are disposed on the front panel of the cabinet 11. Further, the compressor inverter 17 i and the electronic expansion valve 22 are connected to the output port of the controller main body 42.

  The chiller C configured as described above can be operated as an independent chiller by a single chiller C. Therefore, the pressure pump 20 operates during operation, and the cooling water Lw in the coolant tank 2 is supplied to the outside via the heat exchanger (cooling unit) 19 and the supply port 3s, and cools the cooled portion M to be described later. In addition, the cooling water Lw heat-exchanged by the cooled part M is returned to the coolant tank 2 again through the return port 3r. At this time, the temperature of the cooling water Lw supplied from the supply port 3 s is detected by an outlet temperature sensor (not shown) disposed near the supply port 3 s, and the compressor inverter connected to the compressor 17 by the chiller controller 41. 17i, the cooling device 5 including the electronic expansion valve 22, and the like are controlled, and the temperature is controlled so that the temperature of the cooling water Lw becomes a preset target temperature. In addition, by the rotation of the blower fan 12, the inside of the outside air heat exchange chamber Rc is sucked, whereby air cooling air (outside air) A is sucked from the intake ports 11 i and 11 i provided on the side surfaces (front and back) of the cabinet 11. The heat exchange units 14p and 14q and the condensation units 13p and 13q pass through the exhaust port 11e provided at the upper end of the cabinet 11. The water Lwm is sprayed from the spray nozzles Ns... Under a predetermined condition such as a heavy load, the air cooling air A is cooled by using the latent heat at the time of evaporation, and the outside air temperature is decreased. Under the conditions, the circulation pump 18 is operated, and the cooling water Lw in the cooling liquid tank 2 is circulated to the heat exchange units 14p and 14q, whereby the cooling water Lw is cooled by the outside air temperature, that is, free cooling is performed. .

  Next, the structure of the connection operation system 1 of the chiller which concerns on this embodiment using such a chiller C is demonstrated with reference to FIGS.

  This embodiment is an example in which four chillers C... Are connected, and as shown in FIG. On the other hand, in FIG. 2, M indicates a portion to be cooled such as a machine tool that is cooled by the cooling water Lw supplied from the coupled operation system 1. Each chiller C ... and the cooled part M are connected by a supply pipe Ps and a return pipe Pr. In this case, one end (outlet) of the supply pipe Ps is connected to the supply port Mi of the cooled part M, and one end (inlet) of the return pipe Pr is connected to the outlet Me of the cooled part M. On the other hand, the supply port 3s in each chiller C ... is joined and connected in the middle of the supply pipe Ps through a series connection circuit of the supply on / off valve 51 and a constant flow valve 52 that maintains the flow rate constant, and the return in each chiller C ... The port 3r is branched and connected in the middle of the return pipe Pr via the return opening / closing valve 53. At this time, the supply port 3s and the return port 3r of the chiller C located on the most upstream side with respect to the cooled portion M are connected to the other end (inlet) of the supply pipe Ps and the other end (outlet) of the return pipe Pr. Connect each one. Thereby, the circulation path of the cooling water L in each chiller C ... is connected in parallel via the supply piping Ps and the return piping Pr.

  On the other hand, as shown in FIG. 2 and FIG. 6, a sealed internal hollow pressure equalizing tube 8 is horizontally installed. The pressure equalizing pipe 8 can be configured by closing both ends of a pipe member 8p having a predetermined diameter or more. For this reason, each chiller C is provided with a pressure equalization port (equal pressure equalization pipe connection port) 55. The inner ends of the pressure equalization ports 55 are connected to the lower part of the coolant tank 2. The outer ends of 55... Are connected to the peripheral surface of the pipe member 8 p located nearest through the pressure equalizing on / off valves 56. Accordingly, the coolant tanks 2 of each chiller C communicate with each other through the pressure equalizing pipe 8. For this reason, it is desirable to cover the entire area from the pressure equalizing port 55 of each chiller C to the pressure equalizing pipe 8 with a heat insulating material so that the temperature of the cooling water Lw is not affected by the outside air temperature. Thus, if the pressure equalizing pipe 8 connected in common to the cooling liquid tank 2 of each chiller C ... is provided, the liquid level of the cooling liquid L accommodated in the cooling liquid tank 2 of each chiller C ... has the same height. Therefore, the variation in the relative flow rate of the coolant L and the variation in the cooling capacity (temperature control) between the chillers C... Can be eliminated, and the flow rate and temperature control can be further stabilized.

  On the other hand, a centralized control device 7 having a computing function is separately provided. As shown in FIG. 3, the central control device 7 includes a central control device main body 62 including hardware such as a CPU. The centralized control device main body 62 includes a memory 62m, and in this memory 62m, a program for storing at least software for executing various arithmetic processes and control processes for executing the communication operation method according to the present embodiment. It has an area 62mp and a data area 62md for writing various data including setting data. Further, an operation unit 63 and a display unit 64 are attached to the centralized control device main body 62.

  Therefore, the central control apparatus 7 can perform the following basic processes in relation to the coupled operation method according to the present embodiment. That is, during the operation of the linked operation system 1, the load factor X of each chiller C is monitored, and if it becomes equal to or less than the preset first monitoring load factor Xd, the coolant supply function of some chillers C is excluded. When the second monitoring load factor Xu is equal to or higher than the preset second monitoring load factor Xu, control is performed to restore a part of the stopped chillers C, and all chillers C in operation are stopped when the chillers C are stopped. The total control amount Dr of ... is divided into the number of chillers C except the chiller C to be stopped, and the control applied to each chiller C is performed, and when the stopped chiller C is returned, The total amount of control Da of the chillers C... Can be divided into the number of chillers C including the chiller C to be restored and the control applied to each chiller C.

  Further, the central control device main body 62 is connected to the controller main bodies 42 provided in each chiller C so as to be capable of bidirectional communication. In this case, the communication unit built in the central control device main body 62 and the communication unit built in each controller main body 42 are connected by a wired communication method or a wireless communication method. On the other hand, as shown in FIG. 2, a supply cooling water temperature sensor 65 that detects the temperature of the cooling water Lw supplied to the cooled portion M is attached to the supply pipe Ps. In this case, the attachment position of the supply cooling water temperature sensor 65 is a junction point where the supply port 3s of the chiller C is connected to the supply pipe Ps, and is selected downstream of the junction point pe located closest to the cooled portion M. It is desirable to do. The supply coolant temperature sensor 65 is connected to the sensor input port of the central control device main body 62. Further, a return cooling water temperature sensor 66 for detecting the temperature of the heat exchanged cooling water Lw returned from the cooled portion M is attached to the return pipe Pr. In this case, the position where the return cooling water temperature sensor 66 is attached is a branch point where the return port 3r of the chiller C is connected to the return pipe Pr, and the upstream position of the branch point pj located closest to the part to be cooled M is selected. It is desirable to do. The return cooling water temperature sensor 66 is connected to the sensor input port of the centralized controller main body 62.

  Next, the operation of the coupled operation system 1 including the coupled chiller operation method according to the present embodiment will be described with reference to FIGS. 1 and 7 with reference to FIGS.

  FIG. 1 is a flowchart showing a processing procedure of the coupled operation method according to the present embodiment. Now, assume that the contact operation system 1 is in operation and all the chillers C are in operation (step S1). During the operation of the communication operation system 1, the temperature (detected temperature Td) of the cooling water Lw supplied to the cooled part M is detected by the supply cooling water temperature sensor 65 and applied to the centralized control device 7. Thereby, the centralized control device 7 gives the optimum chiller target temperature Toc corresponding to the operating state of each chiller C to each chiller C so that the detected temperature Td becomes the preset target temperature To. Grant (send). On the other hand, each chiller C ... is independently controlled. That is, the PID control (feedback control) for the temperature is performed so that the temperature (chiller detection temperature Tdc ...) of the cooling water Lw ... supplied from the supply port 3s ... of each chiller C ... becomes the chiller target temperature Toc ... Done. In the example, the target temperature To of the cooling water Lw is set to 25 [° C.]. The differential (tolerance) with respect to the target temperature To is ± 1 [° C.], that is, the upper differential temperature To is 26 [° C.] and the lower differential temperature Tod is 24 [° C.], and high-precision temperature control is required. Thereby, in each chiller C ..., the temperature (chiller detection temperature Tdc ...) of the cooling water Lw ... supplied from the supply port 3s ... to the outside by an unillustrated outlet temperature sensor provided near the supply port 3s ... PID control (feedback control) with respect to the temperature is performed so that the detected temperature Tdc... Becomes the target temperature Toc.

  On the other hand, during the operation of the coupled operation system 1, the central control device 7 monitors the load factor X of each chiller C (steps S2 and S3). The load factor X is a ratio of the actual load in operation with respect to the rated load, and can be obtained by a control signal or the like in the control system 6 of each chiller C..., So data related to each load factor X. It is transmitted to the control device main body 62. By the way, in the chiller C, there is usually an optimum load factor at which the most efficient operation is performed. If the optimal load factor of the illustrated chiller C is, for example, 40 [%], the operation efficiency is lowered by the load factor being lowered or increased from 40 [%]. For this reason, in consideration of the optimum load factor of the chiller C, the first monitoring load factor Xd serving as the lower limit threshold and the second monitoring load factor Xu serving as the upper threshold are set in advance, and based on the load factors Xd and Xu. Monitor the load factor X. In the present embodiment, description will be made assuming that the first monitoring load factor Xd is set to 30 [%] and the second monitoring load factor Xu is set to 50 [%].

  Now, during operation, when the load decreases and the load factor X of each chiller C also decreases, all the load factors X ... of the four chillers C ... become the first monitored load factor Xd or less. Assume (step S4). Thereby, the centralized control device 7 determines the change state of the load factor X when the load factor X ... in the chillers C ... becomes equal to or less than the first monitoring load factor Xd. At this time, when the change state of the load factor X is in a stable state or a descending state, a process for stopping one chiller C except for the coolant supply function is performed (step S5). In this case, the cooling liquid supply function includes at least the operation of the pressure feed pump 20. Therefore, the operation of the cooling device 4 and the circulation pump 18 is stopped by stopping the chiller C. In addition, when the change state of the load factor X is increasing, the process for stopping the chiller C is not performed.

  As described above, if the control is performed to stop the chiller C on the condition that the load factor X is not increasing when the load becomes lower than the first monitoring load factor Xd, the load factor X becomes a temporary disturbance. Thus, the case where the first monitoring load factor Xd is reached can be eliminated, so that an unnecessary change in the number of chillers C... Can be avoided and the stability of the entire system 1 can be improved. In the example, the load factor X in all the chillers C... Is assumed to be equal to or less than the first monitoring load factor Xd. However, the number of the chillers C at this time is arbitrary. Can be arbitrarily set, for example, on condition that the first monitoring load factor Xd or less. Further, the determination of the change state of the load factor X may be performed for the chiller C that has finally become the first monitored load factor Xd or less, or based on the average of the change states of all the chillers C. May be. Further, it is desirable to select the chiller C that has the longest operation period at the time of determination as the chiller C to be stopped.

  When the chiller C is stopped, the total control amount Dr of all the chillers C in operation is divided into the number of chillers C except the chiller C to be stopped and applied to each chiller C. Specifically, first, the operation amount of the integral control is obtained by the calculation process of [total operation amount of accumulation control in PID control before stop (accumulation deviation)] / [number of chiller operation after stop] (step S6). . Then, the obtained operation amount of the integral control is applied to each chiller C ... other than the chiller C to be stopped (step S7). In the case of the example, the operation amount obtained by dividing the total sum of the operation amounts of the integral control in the four chillers C... Into 1/3 is obtained, and the operation amount is changed in each chiller C other than the chiller C to be stopped. To process. Moreover, the control which stops the selected one chiller C is performed with the change of the operation amount (step S8). In this case, as described above, control such as stopping the operation of the compressor motor in the compressor 17 or stopping the operation of the circulation pump 18 is performed without stopping the operation of the pump 20. Thereby, since the cooling water Lw which is not temperature-controlled is supplied from the stopped chiller C, the entire flow rate of the cooling water Lw supplied to the cooled part M does not change.

  As a result, if the load factor X of each of the four chillers C immediately before the chiller C is stopped is 30 [%], the load of each chiller C after the chiller C is stopped. The rate X is 40 [%] (optimum load factor). Thereafter, when the load factor X becomes 30 [%] or less again during the operation of the three chillers C..., The same process is performed to stop one chiller C (step S8, S3, S4, S5 ...). Therefore, when the load factor X is gradually reduced, the number of chillers C to be operated can be sequentially reduced in response to the reduced state of the load factor X, and finally only one chiller C is used. Operation in is possible. As described above, when the chiller C is stopped, for each chiller C..., The integral control obtained by [total operation amount of integral control in PID control before stop] / [number of chiller operation after stop] is calculated. If control to change to the operation amount is performed, the detection result from the existing temperature sensor that detects the temperature of the coolant L supplied from each chiller C... There is an advantage that it can be easily implemented using an operation amount (a control signal or the like for the compressor provided in the cooling device 5).

  FIG. 7 shows temperature change data when such processing is performed. In FIG. 7 illustrated, for easy understanding, the load factor X is less than or equal to the first monitoring load factor Xd (30 [%]) during operation of two chillers (first chiller, second chiller) C. It shows a state in which one chiller C is stopped at time tc. As is apparent from the figure, until the time point tc, the temperature of the cooling water Lw supplied from the first chiller C is controlled to the chiller detection temperature T1, and the temperature of the cooling water Lw supplied from the second chiller C is The temperature of the cooling water Lw supplied to the part M to be cooled, that is, the detected temperature Td detected by the supply cooling water temperature sensor 65 is controlled near the target temperature To. Then, after stopping the first chiller C at the time point tc, the chiller detection temperature T1 of the first chiller C rises, and the temperature change at this time is 27 [° C., which is the water temperature at normal temperature through overshoot. ] Stable in the vicinity. On the other hand, the chiller detection temperature T2 of the second chiller C shows an almost opposite temperature change with respect to the chiller detection temperature T1 of the first chiller C because the operation amount of the integral control is changed at the time point tc. It is controlled in the vicinity. As a result, the temperature (detected temperature Td) of the cooling water Lw supplied to the cooled part M is maintained near the target temperature To. The detected temperature Td immediately after the time point tc temporarily shows unstable behavior, but does not exceed the upper differential temperature Tou.

  On the other hand, it is assumed that the two chillers C are in a stopped state and the remaining two chillers C are in operation. Then, during operation, it is assumed that the load factors X of both the chillers C ... are equal to or higher than the second monitoring load factor Xu (steps S3, S4, S9). Thereby, the centralized control device 7 determines the change state of the load factor X when the load factor X in the chillers C becomes equal to or higher than the second monitoring load factor Xu, and the change state is stable or increasing. In the state, the process for returning the stopped chiller C, that is, the process for returning the stopped function except for the coolant supply function is performed (step S10). Therefore, when the change state of the load factor X is decreasing, the process for returning the chiller C is not performed. As described above, if the control is performed to return the chiller C on condition that the load factor X is not decreasing when the second monitored load factor Xu is equal to or higher, the load factor X is temporarily disturbed. Therefore, it is possible to eliminate the case where the second monitoring load factor Xu is reached, so that an unnecessary change in the number of chillers C... Can be avoided and the stability of the entire system 1 can be improved. In the example, the load factor X in all the chillers C... Is set to be equal to or higher than the second monitoring load factor Xu. However, the number of the chillers C is arbitrary, for example, one chiller C in half. Can be arbitrarily set, for example, on the condition that the second monitoring load factor Xu is greater than or equal to. Further, the determination of the change state of the load factor X may be performed on the chiller C that has finally reached the second monitoring load factor Xu or on the basis of the average of the change states in all the chillers C. May be. Furthermore, it is desirable to select the chiller C that has the longest stop period at the time of determination as the chiller C to be stopped.

  By the way, since the process of stopping the chiller C while the load factor X is decreasing is a stop process in a state where there is a surplus power, it can be sequentially stopped one by one. However, the process of returning the chiller C while the load factor X is increasing is, so to speak, a recovery process in which there is no surplus power. Therefore, when the load increases rapidly, the cooling capacity may not be able to follow. The Therefore, when the load factor X increases, an increase rate of the load factor X is obtained by calculation processing (step S11). Then, the number of chillers C to be returned is determined according to the magnitude of the increase rate (step S12). That is, the number of chillers C to be restored is determined based on the calculated rate of increase. Therefore, in the case of the example, when the rate of increase exceeds the set standard, the two chillers C can be returned simultaneously. As described above, when the chiller C is returned, the rate of increase of the load factor X is obtained, and the number of chillers C to be returned is determined based on this rate of increase. Since the chillers C can be restored, there is an advantage that even if the load suddenly increases due to some factor, it is possible to cope with it accurately.

  On the other hand, when returning the chillers C, the total control amount Da of all the chillers C in operation is divided into the number of chillers C including the chillers C to be returned, and control is applied to each chiller C. Specifically, first, the operation amount of the integral control is obtained by a calculation process of [total operation amount of integral control in PID control before return] / [number of chiller operation after return] (step S13). Then, the obtained operation amount of integral control is applied to each chiller C during operation including the chiller C to be restored (step S14). In the case of the example, the operation amount obtained by dividing the sum total of the operation amounts of the integral control in the two chillers C... Is divided into 1/3, and changed to be the operation amount in each chiller C including the chiller C to be returned. To process. Further, along with the change in the operation amount, control is performed to return the selected one chiller C (step S15). That is, the compressor motor and the circulation pump 18 in the stopped compressor 17 are returned to be operable.

  As a result, if the load factor X of each of the two chillers C immediately before returning the chiller C is 50 [%], the load of each chiller C after returning one chiller C. The rate X is 33.3 [%]. Thereafter, when the load factor X becomes 50 [%] or more again during operation of the three chillers C, control for returning the chiller C is performed by the same processing (steps S15, S3, S4). , S9 ...). Therefore, when the load factor X increases, the number of chillers C to be operated can be sequentially increased in response to the increased state of the load factor X, and finally all four chillers C are operated. Can be made. Thus, when returning the chiller C, for each chiller C..., In the PID control determined by [total operation amount of integral control in PID control before return] / [number of chiller operation after return]. If control is performed to change the operation amount to integral control, the detection result and control from an existing temperature sensor that detects the temperature of the coolant L supplied from each chiller C. There is an advantage that it can be easily implemented by utilizing the operation amount of the system 6 (control signal for the compressor provided in the cooling device 5).

  Therefore, according to the chiller connection operation method and the connection operation system 1 according to the present embodiment, for the portion M to be cooled for which the cooling water Lw having a constant flow rate is required by highly accurate and stable temperature control. Even when a plurality of chillers C... Are connected in parallel to each other, it is possible to sufficiently meet the requirements of the cooled portion M and to connect a plurality of chillers in parallel. Merits of linked operation, for example, flexible operation control such as stopping (or returning) some chillers C due to a decrease (or increase) in the load factor X can be performed. As a result, each chiller C... Can be operated near the load factor X with the highest efficiency, and the unused chillers C. Further, since the chillers C can be configured by simply connecting them in parallel, the number of chillers C to be connected can be easily changed (increased or decreased). As a result, it is possible to construct a linked operation system 1 excellent in adaptability and versatility, such as being able to flexibly cope with various uses, and also contributing to cost reduction of the entire system.

  The preferred embodiment has been described in detail above, but the present invention is not limited to such an embodiment, and departs from the gist of the present invention in the detailed configuration, shape, material, quantity, control method, and the like. It can be changed, added, or deleted as long as it is not.

  For example, in the embodiment, when stopping the chiller C, for each chiller C..., The integral obtained by [total amount of operation of integral control in PID control before stop] / [number of chiller operation after stop]. When the control is changed to the operation amount of the control, and when the chiller C is returned, for each chiller C ... [total sum of the operation amount of the integral control in the PID control before return] / [chiller after return] Although the control to change to the operation amount of the integral control in the PID control obtained by the number of operating units] is shown, other control methods may be used. In short, the cooling water Lw when the chiller C is stopped or returned Various control methods can be adopted as long as the temperature (detected temperature Td) is a control method that does not deviate from the differential. Therefore, for example, an open loop control method may be employed so that a predetermined operation pattern is obtained for a certain period from when the chiller C is stopped or returned, or a feed forward control method may be employed. In particular, when the feed-forward control method is adopted, the current output (input) of the compressor provided in the cooling device 5 can be forcibly changed, and then can be shifted to normal PID control (feedback control). It can be implemented easily and reliably by using a relatively general-purpose control method.

  On the other hand, the first monitoring load factor Xd and the second monitoring load factor Xu may each be applied with a single set value, or set values having different sizes corresponding to the number of chillers C at the time of application. May be applied. When setting values having different sizes are applied, optimization for all setting values can be achieved. In addition, as an example of the configuration of the outdoor air heat exchanger 14, the V-shaped example is given. However, the configuration in which one or two heat exchange units 14p and 14q, which are the most general configuration, are erected in parallel or the X-shaped configuration is used. It does not exclude other configurations such as the configuration described above. The coolant L includes the exemplified coolant water Lw and various solutions such as antifreeze solution, and the water Lwm includes various fresh water such as tap water and well water. In the present invention, control cooling is a concept including heating.

  The connection operation method and system according to the present invention can be used for various chillers that are used by being connected to various parts to be cooled such as machine tools that need to be cooled by circulating a coolant.

  1: connected operation system, 2: coolant tank, 3s: supply port, 3r: return port, 4: coolant circulation system, 5: cooling device, 6: control system, 7: centralized control device, 8: pressure equalizing pipe, L: Coolant, Lw: Cooling water, M: Part to be cooled, C ...: Chiller

Claims (7)

  Coolant circulation in which the coolant stored in the coolant tank is supplied from the supply port to an external cooled part and the heat-exchanged coolant returned from the cooled part to the return port is stored in the coolant tank A chiller connection operation method in which a plurality of chillers having a system, a cooling device for cooling the coolant supplied from the supply port, and a control system for controlling at least the cooling device are connected in parallel. In addition, the cooling liquid tank in each chiller is connected by a common pressure equalizing pipe, and a central control device having a computing function is connected to the control system of each chiller, thereby monitoring the load factor of each chiller. However, if it became below the preset first monitoring load factor, it was stopped except for the coolant supply function of some chillers, and became above the preset second monitoring load factor Then, control is performed to restore some of the chillers that have been stopped. On the other hand, when stopping the chillers, the total control amount of all chillers in operation is divided into the number of chillers excluding the chillers to be stopped. When the stopped chiller is restored, the total control amount of all chillers in operation is divided into the number of chillers including the restored chiller and applied to each chiller. A chiller connection operation method characterized by the above.   2. The chiller connection operation method according to claim 1, wherein when the load ratio becomes equal to or lower than the first monitoring load factor, control is performed to stop the chiller on condition that the load factor is not increasing.   When stopping the chiller, the feed control or the integral control operation obtained by [total operation amount of integral control in PID control before stop] / [number of chiller operation after stop] is performed for each chiller. 3. The chiller connection operation method according to claim 1, wherein control is performed to change the amount.   The chiller connection operation according to claim 1, 2 or 3, wherein when the load ratio becomes equal to or greater than the second monitoring load factor, control is performed to return the chiller on condition that the load factor is not decreasing. Method.   The chiller connection operation according to any one of claims 1 to 4, wherein when the chiller is returned, an increase rate of the load factor is obtained, and the number of chillers to be returned is determined based on the increase rate. Method.   When returning the chiller, for each chiller, feed-forward control, or integration in PID control obtained by [total operation amount of integral control in PID control before return] / [number of chiller operation after return] The chiller connection operation method according to any one of claims 1 to 5, wherein control for changing to an operation amount of control is performed.   Coolant circulation in which the coolant stored in the coolant tank is supplied from the supply port to an external cooled part and the heat-exchanged coolant returned from the cooled part to the return port is stored in the coolant tank A chiller coupled operation system in which a plurality of chillers having a system, a cooling device that cools the coolant supplied from the supply port, and a control system that controls at least the cooling device are connected in parallel. In addition, each of the chillers includes a pressure equalizing pipe that is commonly connected to the cooling liquid tank, and is connected to a control system of each chiller to monitor the load factor of each chiller, and to set a first monitoring load factor that is set in advance. If the following conditions are met, control is performed to stop some of the chillers except for the coolant supply function, and to reset some of the stopped chillers if they exceed the preset second monitoring load factor. On the other hand, when stopping the chiller, the total control amount of all chillers in operation is divided into the number of chillers excluding the chiller to be stopped and applied to each chiller, and the stopped chiller is restored And a centralized control device having a computing function for performing control to be applied to each chiller by dividing the total control amount of all chillers in operation into the number of chillers including the chiller to be restored. Chiller linked operation system.

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