JP5412193B2 - Turbo refrigerator - Google Patents

Description

  The present invention is a so-called free system that produces cold water by evaporating the refrigerant on the evaporator side using the refrigerant condensing pressure in the condenser as the operating pressure without operating the compressor under conditions where the cooling water temperature is lower than the cold water temperature. The present invention relates to a turbo refrigerator having a free cooling function.

  The turbo refrigerator is a compressor for compressing a refrigerant having an inlet vane, a condenser for condensing the refrigerant using cooling water as a cooling source, a throttle mechanism for depressurizing the refrigerant, and evaporating the refrigerant to cool the cold water. A refrigerating cycle is provided in which the evaporator and the evaporator are sequentially connected by a refrigerant flow path. In a heat source system such as a factory using such a turbo chiller, there is a cold load even at a low outside air temperature such as a winter or an intermediate period, and the chiller may be operated. On the other hand, when the outside air temperature is low, the cooling water temperature supplied to the condenser may be lower than the cooling water temperature at the outlet of the evaporator. In this case, in the centrifugal chiller, the pressure in the condenser is smaller than the pressure in the evaporator, so the turbo compressor is stopped and the refrigerant condensation pressure in the condenser is used as the operating pressure to evaporate the refrigerant on the evaporator side. The refrigerant gas is allowed to flow from an evaporator having a high internal pressure to a condenser having a low internal pressure to form a refrigeration cycle to produce cold water.

  As described above, an example of a turbo chiller having a so-called free cooling function in which a turbo compressor is stopped under a condition that the cooling water temperature is lower than the cold water temperature, and a refrigeration cycle is formed in this state to produce cold water. Is shown in Patent Document 1. In this turbo refrigerator, the gas sides of the evaporator and the condenser are connected by a gas pipe having an on-off valve, and the liquid sides of the evaporator and the condenser are connected by a liquid pipe having an on-off valve. The connected configuration is assumed. If the cooling water temperature is lower than the cold water temperature, the compressor is stopped, and the on-off valves in the gas pipe and the liquid pipe are both opened, so that the refrigerant gas evaporated on the evaporator side is gas piped by the differential pressure. The liquid refrigerant condensed in the condenser is caused to flow to the evaporator through a liquid pipe to form a refrigeration cycle, and cold water is taken out from the evaporator.

Japanese Patent Laid-Open No. 10-9695

  Patent Document 1 discloses a technique for stopping a compressor and opening an on-off valve in a gas pipe and a liquid pipe to perform a free cooling operation of a turbo refrigerator under a condition where the cooling water temperature is lower than the cold water temperature. It has been described. However, there is no specific description regarding temperature control during free cooling operation. In general, temperature control during free cooling operation is performed by flow control and on / off control on the side of auxiliary equipment such as cooling water pumps and cooling water pumps with the centrifugal chiller (turbo compressor) stopped. In reality, there is a problem that the temperature control band is narrow, the temperature fluctuation is large, and the controllability is poor. For this reason, it has stopped using in a limited range.

  The present invention has been made in view of such circumstances, and in a centrifugal chiller having a free cooling function, the temperature control control band during free cooling operation can be widened, An object of the present invention is to provide a turbo refrigerator capable of improving temperature controllability.

In order to solve the above problems, the turbo refrigerator of the present invention employs the following means.
That is, a turbo refrigerator according to the present invention includes a turbo compressor for compressing a refrigerant having an inlet vane, a condenser for condensing the refrigerant using cooling water as a cooling source, a throttle mechanism for depressurizing the refrigerant, and evaporating the refrigerant. And an evaporator that cools the chilled water is sequentially connected by the refrigerant flow path to form a refrigeration cycle, and the turbo compressor is stopped under the condition that the cooling water temperature is lower than the chilled water temperature, and the condensation In a turbo chiller having a free cooling function for evaporating the refrigerant on the evaporator side using the refrigerant condensing pressure in the cooler as an operating pressure and taking out cold water, the cooling water temperature is more than the cold water temperature. setting only the the compressor stop control mode section for controlling the temperature of chilled water to the turbo compressor in a stopped state to a set temperature at a low condition, the compressor stop control mode section, pressure A temperature control unit for controlling a cooling capacity by controlling a hot gas bypass valve of a hot gas bypass circuit connecting the inlet vane and the gas side of the condenser and the evaporator in the machine stop control mode, The temperature adjustment control unit is configured to control the cooling capacity by controlling the opening degree of the inlet vane and the opening degree of the hot gas bypass valve according to the cold water temperature in the compressor stop control mode. It is characterized by.

According to the present invention, under the condition that the cooling water temperature is lower than the cold water temperature, the pressure in the condenser is smaller than the pressure in the evaporator, so the turbo compressor is stopped and the refrigerant condensing pressure in the condenser is used as the operating pressure. Cold water is produced by evaporating the refrigerant on the evaporator side. At this time, the turbo chiller is controlled by the compressor stop control mode unit, and the chilled water temperature can be controlled to the set temperature by making use of the precise temperature control function. Accordingly, it is possible to widen a temperature control band during so-called free cooling operation in which the turbo compressor is stopped, and to improve temperature controllability. In particular, the compressor stop control mode unit includes a temperature control unit that controls the cooling capacity by controlling the hot gas bypass valve of the hot gas bypass circuit that connects the gas side of the inlet vane and the condenser and the evaporator, The temperature control control unit controls the opening degree of the inlet vane of the turbo compressor and the opening degree of the hot gas bypass valve of the hot gas bypass circuit according to the cold water temperature, and the flow rate of the refrigerant gas flowing from the evaporator side to the condenser side Since the cooling capacity can be finely controlled in a wide range by adjusting the temperature, the temperature controllability can be greatly improved compared to the case where the cooling water temperature is controlled by the flow rate control or on / off control of the cooling water pump or the cooling water pump. .

  Furthermore, the turbo chiller of the present invention is the above-described turbo chiller, wherein the temperature control unit is configured to fully close or fully open the inlet vane according to the cold water temperature in the compressor stop control mode, The cooling capacity is controlled by controlling the opening degree of the hot gas bypass valve.

  According to the present invention, the temperature adjustment control unit opens or closes the inlet vane of the turbo compressor at an arbitrary threshold according to the cold water temperature, and controls the opening degree of the hot gas bypass valve from the evaporator side. The cooling capacity can be finely controlled by adjusting the flow rate of the refrigerant gas flowing to the condenser side. Thereby, the temperature controllability can be greatly improved.

  Furthermore, the turbo chiller of the present invention is the first control valve according to any one of the above-described turbo chillers, wherein the refrigerant liquid condensed in the condenser is caused to flow between the condenser and the evaporator. The 1st liquid side circuit provided with was provided.

  According to the present invention, in the compressor stop control mode, the first control valve is controlled to open and close, and the liquid refrigerant condensed on the condenser side is caused to flow to the evaporator side via the first liquid side circuit. The refrigeration cycle can be formed in a state where the operation is stopped. Accordingly, cold water can be produced by free cooling operation with the turbo compressor stopped without consuming power for the turbo compressor, and energy saving can be achieved.

  Furthermore, the turbo refrigerator of the present invention is the above-described turbo refrigerator, wherein the first control valve has an opening degree according to a liquid refrigerant level in the condenser and the evaporator in a compressor stop control mode. It is controlled.

  According to the present invention, in the compressor stop control mode, it is possible to hold liquid refrigerant at appropriate liquid levels in the condenser and the evaporator by controlling the opening degree of the first control valve. Thereby, the condensation amount and evaporation amount of the refrigerant in the condenser and the evaporator can be made substantially equal, and a stable free cooling operation can be performed.

  Furthermore, the turbo chiller according to the present invention is the turbo chiller according to any one of the above-described turbo chillers, wherein the refrigerant liquid condensed by the condenser is transported to the evaporator between the condenser and the evaporator. A second liquid side circuit including a valve and a refrigerant pump is provided.

  According to the present invention, in the compressor stop control mode, the second control valve is opened, and the refrigerant pump is operated so that the liquid refrigerant condensed on the condenser side via the second liquid side circuit is evaporated. Can be transported to the side. For this reason, a refrigeration cycle can be formed with the turbo compressor stopped regardless of the positions of the condenser and the evaporator. Therefore, cold water can be manufactured by free cooling operation with the turbo compressor stopped, and energy saving can be achieved. In addition, the circulation capacity of the refrigerant can be increased and the maximum capacity during the free cooling operation can be improved, and the installation position of the condenser and the evaporator is not restricted and the degree of freedom in design can be increased. The refrigerant pump is preferably an inverter-driven variable capacity type so that the refrigerant circulation amount can be adjusted.

  Furthermore, the turbo chiller of the present invention is the above-described turbo chiller, in which the evaporator is from the refrigerant liquid sucked into the refrigerant pump from the condenser via the second control valve and / or from the evaporator. A spraying device for spraying refrigerant liquid sucked into the refrigerant pump onto a heat transfer pipe of the evaporator via a third control valve provided in a refrigerant liquid circuit connecting the evaporator and the suction side of the refrigerant pump It is characterized by having.

  According to the present invention, since the evaporator is configured to include a spraying device that sprays the refrigerant liquid onto the heat transfer tube, the liquid refrigerant condensed on the condenser side and / or the liquid refrigerant accumulated in the evaporator. Can be circulated by the refrigerant pump and sprayed onto the heat transfer tubes. As a result, it is possible to spray the liquid refrigerant on the heat transfer tubes exposed in the gas region and effectively function as a heat transfer surface. Therefore, the maximum capacity during free cooling operation in the compressor stop control mode can be increased, and the amount of refrigerant retained in the evaporator can be reduced.

  Furthermore, the turbo chiller of the present invention is the above-described turbo chiller, wherein the condenser and the evaporator are provided with a level sensor for detecting a liquid refrigerant level, and the second control valve is in a compressor stop control mode. And the liquid level of the liquid refrigerant in the condenser and the evaporator is controlled via the third control valve.

  According to the present invention, in the compressor stop control mode, the liquid level of the liquid refrigerant in the condenser and the evaporator is detected by the level sensor, and the liquid level is controlled via the second control valve and the third control valve. Thus, it is possible to hold the liquid refrigerant at an appropriate liquid level in the condenser and the evaporator. As a result, the amount of refrigerant condensed and evaporated in the condenser and the evaporator can be made substantially equal, and a stable free cooling operation can be performed.

  Furthermore, the turbo refrigerator of the present invention is the above-described turbo refrigerator, in the compressor stop control mode, the liquid level of the liquid refrigerant in the evaporator is such that a certain amount of the heat transfer tube group is exposed to the refrigerant gas region. The remaining heat transfer tube group is controlled to a level at which it is immersed in the refrigerant liquid.

  According to the present invention, in the compressor stop control mode, the liquid refrigerant level in the evaporator is such that a certain amount of the heat transfer tube group is exposed to the refrigerant gas region, and the remaining heat transfer tube group is submerged in the refrigerant liquid. Since the level is controlled, the pressure of liquid refrigerant flowing into the refrigerant pump through the third control valve can be maintained, and the discharge amount (spreading amount) of the refrigerant liquid from the refrigerant pump can be stabilized. Heat transfer performance in the evaporator can be stabilized. Therefore, the ability at the time of free cooling operation can be improved.

  Furthermore, the turbo chiller according to the present invention is the turbo chiller according to any one of the above-described turbo chillers, wherein the turbo compressor is operated in a compressor stop control mode and the refrigerant gas flow from the evaporator to the condenser is A stopper mechanism for preventing the rotation of the turbo compressor is provided.

  According to the present invention, it is possible to prevent the turbo compressor from being rotated by the refrigerant gas flow from the evaporator to the condenser by operating the stopper mechanism in the compressor stop control mode. Thereby, in the compressor stop control mode, it is possible to avoid an unexpected situation that occurs when the turbo compressor rotates while the lubrication system is stopped.

  Furthermore, the turbo chiller of the present invention is the above-described turbo chiller, wherein the temperature adjustment control unit includes a lower limit value of a chilled water temperature setting based on a refrigerant temperature in the condenser cooled by the cooling water. When the cold water temperature is set to be equal to or higher than the lower limit value of the cold water temperature setting in the compressor stop control mode, the temperature control unit controls the inlet vane and the hot gas bypass valve based on the cold water temperature. It is characterized by controlling.

  According to the present invention, the temperature adjustment control unit is provided with the lower limit value of the cold water temperature setting based on the refrigerant temperature in the condenser cooled by the cooling water, and when the cold water temperature is set to the lower limit value or more, the temperature adjustment is performed. The control unit controls the inlet vane and the hot gas bypass valve to perform free cooling operation. That is, in the free cooling operation in the compressor stop control mode, since the operable range is determined by the level of the cooling water temperature, the lower limit value of the cold water temperature setting based on the refrigerant temperature in the condenser cooled in advance by the cooling water is set in advance. By setting it, useless free cooling operation can be avoided.

  Furthermore, the turbo chiller of the present invention is the above-described turbo chiller, wherein the controller for the chiller is in a compressor stop control mode, when the set value of the chilled water temperature is equal to or lower than a lower limit value of the chilled water temperature setting, The turbo compressor is started and the turbo refrigerator is operated in a normal operation mode.

  According to the present invention, in the compressor stop control mode, when the set value of the chilled water temperature is the lower limit value of the chilled water temperature setting, the refrigerator controller starts the turbo compressor and switches the turbo chiller to the normal operation mode. . Thereby, the operation mode can be automatically switched according to the cold water temperature set value, and the turbo refrigerator can be automatically operated.

According to the present invention, in the free cooling operation in which the cooling water temperature is lower than the cooling water temperature and the cooling water is produced with the turbo compressor stopped, the compressor stop control mode unit provides the precise temperature control function of the turbo refrigerator. Since it is possible to control the chilled water temperature to the set temperature by utilizing it, it is possible to widen the temperature control band by free cooling operation, improve the temperature control performance, and expand the practical range. . In particular, the compressor stop control mode unit includes a temperature control unit that controls the cooling capacity by controlling the hot gas bypass valve of the hot gas bypass circuit that connects the gas side of the inlet vane and the condenser and the evaporator, The temperature control control unit controls the opening degree of the inlet vane of the turbo compressor and the opening degree of the hot gas bypass valve of the hot gas bypass circuit according to the cold water temperature, and the flow rate of the refrigerant gas flowing from the evaporator side to the condenser side Since the cooling capacity can be finely controlled in a wide range by adjusting the temperature, the temperature controllability can be greatly improved compared to the case where the cooling water temperature is controlled by the flow rate control or on / off control of the cooling water pump or the cooling water pump. .

It is a refrigerating cycle figure of the turbo refrigerator concerning a 1st embodiment of the present invention. It is a refrigerating cycle figure of the turbo refrigerator concerning 2nd Embodiment of this invention. FIG. 3 is an enlarged longitudinal sectional view of an evaporator of the turbo refrigerator shown in FIG. 2. It is temperature control control explanatory drawing in the compressor stop control mode of the turbo refrigerator concerning 3rd Embodiment of this invention.

Embodiments according to the present invention will be described below with reference to the drawings.
[First Embodiment]
Hereinafter, a first embodiment of the present invention will be described with reference to FIG.
FIG. 1 shows a refrigeration cycle diagram of a turbo refrigerator 1 according to the first embodiment of the present invention. The turbo refrigerator 1 includes a multistage turbo compressor 2 for compressing a refrigerant provided with an inlet vane 3, a condenser 4 that condenses the refrigerant using cooling water as a cooling source, a first throttle mechanism 5 and a second throttle mechanism that depressurize the refrigerant. Gas-liquid separation provided with a gas circuit 8 provided between the throttle mechanism 6 and the first throttle mechanism 5 and the second throttle mechanism 6 and injecting the separated gas-phase refrigerant into the intermediate stage of the multistage turbo compressor 2 A refrigerating cycle 11 is provided in which an evaporator type economizer 7 and an evaporator 9 that evaporates refrigerant and cools cold water are sequentially connected by a refrigerant flow path 10.

  The multi-stage turbo compressor 2 is a multi-stage turbo compressor having two impellers that are rotationally driven by an inverter-driven electric motor (not shown), and is provided between the first impeller and the second impeller from the economizer 7. An intermediate suction port 2A to which the gas circuit 8 is connected is provided. The multistage turbo compressor 2 is locked in a groove or the like provided on a rotary shaft (not shown) during free cooling operation in a compressor stop control mode described later, and is in a stopped state. A stopper mechanism 12 is provided for preventing 2 from rotating due to the refrigerant gas flow.

  The condenser 4 is constituted by a shell-and-tube heat exchanger, and cooling water cooled by a cooling tower 16 via a cooling water pump 14 and a cooling water circuit 15 to a large number of heat transfer tubes 13 provided inside the shell. Can be circulated. The cooling water circuit 15 is provided with a temperature sensor 17 that detects the temperature of the cooling water supplied to the condenser 4. Further, the condenser 4 has a liquid reservoir 18 formed at the bottom thereof, and a level sensor 19 for detecting the liquid level of the liquid refrigerant held in the condenser 4 including the liquid reservoir 18 is provided. ing.

  The first throttle mechanism 5 and the second throttle mechanism 6 are each constituted by an expansion valve. The first throttle mechanism 5 reduces the high-pressure liquid refrigerant condensed and liquefied by the condenser 4 to an intermediate pressure, and gas-liquid separation. It leads to a container type economizer 7. The refrigerant decompressed to the intermediate pressure by the first throttle mechanism 5 is separated into gas-liquid two phases by the economizer 7 so that the gas-phase refrigerant is led to the intermediate suction port 2A of the multistage turbo compressor 2 via the gas circuit 8. It has become. The second throttle mechanism 6 depressurizes the liquid refrigerant separated by the economizer 7 to a low pressure and leads it to the evaporator 9.

  The evaporator 9 is constituted by a shell-and-tube heat exchanger, and a heat exchanger provided on the air conditioning load side via a chilled water pump 21 and a chilled water circuit 22 in a large number of heat transfer tubes 20 provided in the shell. Cold water can be circulated between them. The cold water circuit 22 is provided with a temperature sensor 23 that detects the temperature of the cold water cooled by the evaporator 9. Further, the evaporator 9 is provided with a level sensor 24 that detects the liquid level of the liquid refrigerant held in the evaporator 9.

  Moreover, between the condenser 4 and the evaporator 9, the hot gas bypass circuit 25 provided with the hot gas bypass valve 26 which connects each gas area | region inside each shell, and the liquid area | region inside a shell are connected. A first liquid side circuit 27 having a first control valve 28 is provided, and by closing the first throttle mechanism 5 and the second throttle mechanism 6, the multistage turbo compressor 2 is stopped and free cooling is performed. A refrigerant circulation path for operation is formed. The hot gas bypass circuit 25 also serves as a capacity control circuit that controls the refrigerating capacity by bypassing the hot gas refrigerant from the condenser 4 to the evaporator 9 in the normal operation mode.

  Further, the refrigerating machine controller 29 for controlling the turbo refrigerating machine 1 includes a rotation speed of the multistage turbo compressor 2, an opening degree of the inlet vane 3, an opening degree of the hot gas bypass valve 26, a second throttle mechanism (expansion valve). A normal operation mode control unit 31 that controls the opening degree of 6 and the like so that the temperature of the chilled water supplied from the evaporator 9 to the air conditioning load side becomes the temperature set by the temperature setting unit 30; There is provided a compressor stop control mode unit 32 that controls the multi-stage turbo compressor 2 to be in a stopped state so that the cold water temperature becomes a set temperature under a condition where the cooling water temperature is low.

  The compressor stop control mode unit 32 controls the opening degree of the inlet vane 3 and the opening degree of the hot gas bypass valve 26 in the compressor stop control mode, that is, in the free cooling operation in which the multistage turbo compressor 2 is stopped. Thus, a temperature control unit 33 is provided for controlling the cooling capacity and controlling the chilled water temperature to be the set temperature. In addition, the compressor stop control mode unit 32 has a first control valve 28 in the first liquid side circuit 27 according to the liquid level of the liquid refrigerant in the condenser 4 and the evaporator 9 detected by the level sensors 19 and 24. In the compressor stop control mode, the liquid refrigerant of the appropriate liquid level is held in the condenser 4 and the evaporator 9, respectively.

  Further, the temperature control unit 33 is preset with a lower limit value of the cold water temperature setting based on the refrigerant temperature in the condenser cooled by the cooling water. When the chilled water temperature is set to be equal to or higher than the lower limit value of the chilled water temperature setting in the compressor stop control mode, the temperature control unit 33 controls the inlet vane 3 and the hot gas bypass valve based on the chilled water temperature detected by the temperature sensor 23. 26 is controlled to perform free cooling operation. When the chilled water temperature set value by the temperature setter 30 is input to the chiller controller 29 and the chilled water temperature set value is equal to or lower than the lower limit value of the chilled water temperature setting, the chiller controller 29 causes the multistage turbo compressor 2 to The turbo chiller 1 is automatically switched to the normal operation mode.

With the above configuration, according to the present embodiment, the following operational effects are obtained.
The high-pressure refrigerant gas compressed by the operation of the multistage turbo compressor 2 is sent from the multistage turbo compressor 2 to the condenser 4 and exchanges heat with the cooling water circulated to the heat transfer pipe 13 via the cooling water circuit 15. Is condensed and liquefied. This refrigerant is reduced to an intermediate pressure by the first throttle mechanism 5 and sent to a gas-liquid separator type economizer 7 where it is separated into two phases. The gas phase refrigerant is injected into the compressed refrigerant gas in the multistage turbo compressor 2 through the gas circuit 8 from the intermediate suction port 2A of the multistage turbo compressor 2. The liquid-phase refrigerant supercooled by evaporating and separating the gas-phase refrigerant by the economizer 7 is sent to the second throttle mechanism 6, depressurized to a low pressure, and then sent to the evaporator 9. The refrigerant sent to the evaporator 9 is evaporated and gasified by exchanging heat with the cold water circulated to the heat transfer pipe 20 via the cold water circuit 22 to cool the cold water. The refrigerant gasified by the evaporator 9 is sucked into the multistage turbo compressor 2 and compressed again, and the above cycle is repeated.

  During this time, the centrifugal chiller 1 is operated and controlled so that the chilled water temperature detected by the temperature sensor 23 at the outlet of the evaporator 9 becomes the chilled water temperature set by the temperature setter 30 via the chiller controller 29. . That is, the centrifugal chiller 1 is configured so that the temperature of the chilled water detected by the temperature sensor 23 becomes the temperature set by the temperature setter 30, the rotational speed of the multistage turbo compressor 2, the opening degree of the inlet vane 3, and hot gas. The opening degree of the bypass valve 26, the opening degree of the second throttle mechanism (expansion valve) 6 and the like are appropriately controlled, and the operation is controlled so as to exhibit the ability corresponding to the temperature control load.

  On the other hand, in a heat source system such as a factory, there is a cold load even at a low outside air temperature such as winter, and the turbo refrigerator 1 may be operated. At such a low outside air temperature, the cooling water temperature supplied to the condenser 4 may be lower than the cooling water temperature at the outlet of the evaporator 9. Under such conditions, the internal pressures of the condenser 4 and the evaporator 9 are such that the pressure inside the condenser <the pressure inside the evaporator. In this case, in the centrifugal chiller 1, the multistage turbo compressor 2 is stopped, and the refrigerant on the evaporator 9 side is evaporated using the refrigerant condensing pressure in the condenser 4 as an operating pressure, thereby evaporating the refrigerant gas at a high internal pressure. The cold water can be produced by flowing from the vessel 9 to the condenser 4 having a low internal pressure to form a refrigeration cycle.

  In the present embodiment, during the above-described free cooling operation in which cold water is produced while the multistage turbo compressor 2 is stopped, the turbo refrigerator 1 uses the compressor stop control mode unit 32 to enter the inlet vane of the multistage turbo compressor 2. 3 and the hot gas bypass valve 26 of the hot gas bypass circuit 25 are controlled so that the cold water temperature becomes the set temperature. Specifically, the temperature control unit 33 controls the opening degree of the inlet vane 3 and the opening degree of the hot gas bypass valve 26 so that the cold water temperature detected by the temperature sensor 23 becomes the set temperature, and the evaporator 9 The cooling capacity is controlled according to the temperature control load by adjusting the flow rate of the refrigerant gas flowing from the side to the condenser 4 side.

  As described above, in the compressor stop control mode, the chilled water temperature can be controlled to the set temperature by making use of the precise temperature control function of the turbo chiller 1, so that the multistage turbo compressor 2 is brought into the stop state. In addition, it is possible to widen the temperature control band during the free cooling operation and to improve the temperature control performance. In particular, since the flow rate of the refrigerant gas can be adjusted by controlling the opening degree of the inlet vane 3 and the hot gas bypass valve 26 and the cooling capacity can be finely controlled, the flow rate control or on / off of the cooling water pump 14 or the cooling water pump 21 is possible. Compared with the case of controlling the chilled water temperature by control, the temperature fluctuation range can be reduced and the temperature controllability can be greatly improved.

  Further, a first liquid side circuit 27 having a first control valve 28 for supplying the refrigerant liquid condensed in the condenser 4 to the evaporator 9 is provided between the condenser 4 and the evaporator 9. By flowing the liquid refrigerant condensed on the condenser 4 side due to the head difference through the circuit 27 to the evaporator 9 side, a refrigeration cycle can be formed with the multistage turbo compressor 2 stopped. For this reason, cold water can be manufactured by the free cooling operation by the compressor stop control mode which stopped the multistage turbo compressor 2, the drive power of the multistage turbo compressor 2 is not required, and energy saving can be achieved. Further, during the free cooling operation, the opening degree of the first control valve 28 is controlled according to the liquid level of the liquid refrigerant in the condenser 4 and the evaporator 9 detected by the level sensors 19 and 24, and the condenser 4 and Since the liquid refrigerant at the proper liquid level can be held in the evaporator 9, respectively, the condensation amount and the evaporation amount of the refrigerant in the condenser 4 and the evaporator 9 are made substantially equal, and stable free cooling operation is performed. It can be carried out.

  Further, the temperature adjustment control unit 33 is provided with a lower limit value of the cold water temperature setting based on the refrigerant temperature in the condenser cooled by the cooling water. In the above free cooling operation, since the operable range is determined by the level of the cooling water temperature, by setting in advance a lower limit value of the cold water temperature setting based on the refrigerant temperature in the condenser cooled by the cooling water in advance. , Useless free cooling operation can be avoided. At the same time, the chilled water temperature set value from the temperature setting device 30 is input to the refrigerator controller 29, and when it is below the lower limit value of the chilled water temperature setting, the multistage turbo compressor 2 is started and the turbo chiller 1 is in normal operation. Since the mode can be switched, the operation mode is automatically switched according to the cold water temperature setting value, and the turbo chiller 1 can be automatically operated.

[Second Embodiment]
Next, a second embodiment of the present invention will be described with reference to FIGS.
The present embodiment is different from the first embodiment described above in that a spraying device 40 that sprays liquid refrigerant on the evaporator 9 is provided, and a second control valve is provided between the condenser 4 and the spraying device 40 of the evaporator 9. 42 and the second liquid side circuit 41 provided with the refrigerant pump 43 is different. Since other points are the same as those in the first embodiment, description thereof will be omitted.
FIG. 2 shows a refrigeration cycle diagram of the turbo chiller 1 according to the present embodiment. In the present embodiment, the evaporator 9 is provided with a spraying device 40 for spraying liquid refrigerant on the heat transfer tube 20, and the spraying device 40 and the liquid reservoir 18 of the condenser 4 are opened during the compressor stop control mode. The second control valve 42 that is closed in the normal operation mode and the inverter-driven variable displacement refrigerant pump 43 that conveys the liquid refrigerant are connected to each other via a second liquid side circuit 41.

Further, the bottom of the evaporator 9 and the suction side of the refrigerant pump 43 are refrigerant liquid including a third control valve 45 that circulates the liquid refrigerant in the evaporator 9 to the suction side of the refrigerant pump 43 in the compressor stop control mode. The circuit 44 is connected.
According to the present embodiment having the above configuration, in the compressor stop control mode in which the multistage turbo compressor 2 is stopped, the first throttle mechanism 5 and the second throttle mechanism 6 are closed and the second control valve 42 is opened. By driving the refrigerant pump 43, the refrigerant condensed by the condenser 4 can be conveyed to the spraying device 40 of the evaporator 9 via the second liquid side circuit 41.

  At this time, since the refrigerant is conveyed by the refrigerant pump 43, the liquid refrigerant condensed on the condenser 4 side is conveyed to the evaporator 9 side regardless of the positions of the condenser 4 and the evaporator 9, and the turbo compressor is stopped. A refrigeration cycle can be formed in the state. Therefore, the same effect as the first embodiment can be obtained. Further, since the refrigerant can be forcibly conveyed by the refrigerant pump 43, the circulation amount of the refrigerant can be increased and the maximum capacity during the free cooling operation can be increased, and the installation positions of the condenser 4 and the evaporator 9 are not restricted. , Can increase the degree of design freedom.

  In the normal operation mode, the refrigerant is supplied to the bottom of the evaporator 9, and the evaporator 9 is used in a full liquid state. In this case, as shown in FIG. 3, it is necessary to hold the amount of liquid refrigerant in the evaporator 9 so that all the heat transfer tubes 20 are below the refrigerant liquid level E1. On the other hand, in the compressor stop control mode, the liquid refrigerant condensed by the condenser 4 is opened on the second control valve 42, and the refrigerant pump 43 is operated so as to be sprayed from the spraying device 40 onto the heat transfer tube 20 and evaporated. The liquid refrigerant accumulated in the lower part of the container 9 is circulated to the suction side of the refrigerant pump 43 through the refrigerant liquid circuit 44 and the third control valve 45 and is dispersed from the spraying device 40. In this case, about 40% of the tube group of the heat transfer tubes 20 is exposed to the refrigerant gas region, and the remaining about 60% is below the refrigerant liquid level E2. Therefore, it is necessary to control the refrigerant liquid level to E2.

  By monitoring the refrigerant liquid levels E1, E2 and the refrigerant liquid level in the condenser 4 with the level sensors 19, 24, and controlling the second control valve 42, the third control valve 45, and / or the refrigerant pump 43, etc. In the condenser 4 and the evaporator 9, an appropriate refrigerant liquid level can be ensured as described above. As a result, in the compressor stop control mode, the amount of refrigerant condensed in the condenser 4 and the evaporator 9 and the amount of evaporation can be made substantially equal, and a stable free cooling operation can be performed. In addition, during the free cooling operation, the refrigerant condensed on the condenser 4 side and / or the liquid refrigerant accumulated in the lower part of the evaporator 9 are circulated by the refrigerant pump 43 and dispersed on the heat transfer tube 20. Liquid refrigerant can be sprayed on the heat transfer tubes 20 exposed in the gas region to effectively function as a heat transfer surface. Therefore, the maximum capacity during free cooling operation can be increased, and the amount of refrigerant retained in the evaporator 9 can be reduced.

  Furthermore, in the compressor stop control mode, the liquid level in the evaporator 9 is such that about 40% of the tube group of the heat transfer tubes 20 is exposed to the refrigerant gas region, and the remaining about 60% is below the refrigerant liquid level E2. Therefore, the indentation pressure of the liquid refrigerant flowing into the refrigerant pump 43 via the third control valve 45 is maintained, and the discharge amount of the refrigerant liquid from the refrigerant pump 43, that is, the refrigerant spray amount is stabilized. In addition, the heat transfer performance in the evaporator 9 can be stabilized. Therefore, the maximum capacity during free cooling operation can be improved.

[Third Embodiment]
Next, a third embodiment of the present invention will be described with reference to FIG.
The present embodiment differs from the first embodiment described above in the control mode of the inlet vane 3 and the hot gas bypass valve 26 by the temperature control unit 33. Since other points are the same as those in the first embodiment, description thereof will be omitted.
In the first embodiment described above, the opening degree of the inlet vane 3 and the opening degree of the hot gas bypass valve (HGBP valve) 26 are simultaneously controlled in the compressor stop control mode, but in this embodiment, FIG. As shown in FIG. 4, in the region where the flow rate of the refrigerant gas flowing from the evaporator 9 side to the condenser 4 side is small and the capacity is small, the inlet vane 3 is fully closed and the opening degree control of the hot gas bypass valve 26 is performed. In the region where the flow rate of the refrigerant gas is large and the capacity is large, the capacity control is performed by controlling the opening degree of the inlet vane 3.

  As described above, by performing the capacity control using the hot gas bypass valve 26 in the region where the flow rate of the refrigerant gas is small, delicate capacity control can be performed. In addition, in a region where the flow rate of the refrigerant gas is large, rapid capability control can be performed by performing capability control using the inlet vane 3 whose flow rate greatly changes due to a slight change in opening degree. Therefore, according to the present embodiment, the temperature control band can be expanded, and the cooling capacity can be finely controlled over the entire range to improve the temperature control.

  In addition, this invention is not limited to the invention concerning the said embodiment, In the range which does not deviate from the summary, it can change suitably. For example, in the above-described embodiment, an example using the gas-liquid separator method has been described for the economizer 7, but it is needless to say that an intermediate cooler method may be used. Moreover, although the example using the multistage turbo compressor 2 was demonstrated about the turbo refrigerator 1, the thing using a single stage turbo compressor may be used, and the economizer 7 is not provided in this case.

DESCRIPTION OF SYMBOLS 1 Turbo refrigerator 2 Multistage turbo compressor 3 Inlet vane 4 Condenser 6 2nd throttle mechanism 9 Evaporator 10 Refrigerant flow path 11 Refrigerating cycle 12 Stopper mechanism 17, 23 Temperature sensor 19, 24 Level sensor 25 Hot gas bypass circuit 26 Hot Gas bypass valve 27 First liquid side circuit 28 First control valve 29 Refrigerator controller 30 Temperature setter 31 Normal operation mode control unit 32 Compressor stop control mode unit 33 Temperature control unit 40 Spraying device 41 Second liquid side circuit 42 Second control valve 43 Refrigerant pump 44 Refrigerant liquid circuit 45 Third control valve

Claims (11)

A turbo compressor for compressing a refrigerant having an inlet vane, a condenser that condenses the refrigerant using cooling water as a cooling source, a throttle mechanism that depressurizes the refrigerant, and an evaporator that evaporates the refrigerant and cools the cold water sequentially. The refrigeration cycle is configured by connecting with a refrigerant flow path , and the turbo compressor is stopped under the condition that the cooling water temperature is lower than the cold water temperature, and the refrigerant condensing pressure in the condenser is used as the operating pressure. In the turbo refrigerator having a free cooling function to evaporate the refrigerant on the evaporator side and take out the cold water ,
A controller for refrigerator, set the compressor stop control mode section for controlling the temperature of chilled water set temperature the chilled water temperature above with a turbo compressor in a stopped state the cooling water temperature is lower conditions than,
The compressor stop control mode unit controls a cooling capacity by controlling a hot gas bypass valve of a hot gas bypass circuit that connects the inlet vane and the gas side of the condenser and the evaporator in the compressor stop control mode. It has a temperature control unit to control,
The temperature control unit is configured to control the cooling capacity by controlling the opening degree of the inlet vane and the opening degree of the hot gas bypass valve according to the cold water temperature in the compressor stop control mode. A turbo refrigerator characterized by that. In the compressor stop control mode, the temperature control unit fully closes or fully opens the inlet vane according to the cold water temperature, and controls the cooling capacity by controlling the opening degree of the hot gas bypass valve. The turbo refrigerator according to claim 1 . The first liquid side circuit provided with the 1st control valve which flows the refrigerant | coolant liquid condensed with the said condenser to the said evaporator between the said condenser and the said evaporator is provided, or characterized by the above-mentioned. The turbo refrigerator as described in 2 . The turbo chiller according to claim 3 , wherein the first control valve is controlled in opening degree according to a liquid level of liquid refrigerant in the condenser and the evaporator in a compressor stop control mode. . A second liquid side circuit including a second control valve and a refrigerant pump for conveying the refrigerant liquid condensed in the condenser to the evaporator is provided between the condenser and the evaporator. The turbo refrigerator according to claim 1 or 2 . The evaporator includes a refrigerant liquid sucked into the refrigerant pump from the condenser via the second control valve and / or a refrigerant liquid circuit that connects the evaporator and the suction side of the refrigerant pump from the evaporator. The turbo refrigeration according to claim 5 , further comprising: a spraying device that sprays the refrigerant liquid sucked into the refrigerant pump through the third control valve provided on the heat transfer pipe of the evaporator. Machine. In the condenser and the evaporator, a level sensor for detecting the liquid refrigerant level is provided, and in the compressor stop control mode, in the condenser and the evaporator via the second control valve and the third control valve. The turbo refrigerator according to claim 6 , wherein the liquid level of the liquid refrigerant is controlled. In the compressor stop control mode, the liquid refrigerant level in the evaporator is at a level at which a certain amount of the heat transfer tube group is exposed in the refrigerant gas and the remaining heat transfer tube group is submerged in the refrigerant liquid. The turbo refrigerator according to claim 7 , wherein the turbo refrigerator is controlled. The turbo compressor is provided with a stopper mechanism that operates in a compressor stop control mode and prevents rotation of the turbo compressor due to a refrigerant gas flow from the evaporator to the condenser. The turbo refrigerator according to any one of claims 1 to 8 . The temperature control unit is provided with a lower limit value of a chilled water temperature setting based on the refrigerant temperature in the condenser cooled by the cooling water, and the chilled water temperature is set to the chilled water temperature setting in the compressor stop control mode. The turbo according to any one of claims 1 to 9 , wherein when the temperature is set to a lower limit value or more, the temperature control unit controls the inlet vane and the hot gas bypass valve based on the cold water temperature. refrigerator. The compressor controller starts the turbo compressor and operates the turbo refrigerator in a normal operation mode when the set value of the cold water temperature is equal to or lower than the lower limit value of the cold water temperature setting in the compressor stop control mode. The turbo refrigerator according to claim 10 .

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