JP3258687B2 - Abnormality detector for absorption refrigerator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an absorption refrigerator, and more particularly to an abnormality in a solution heat exchanger for exchanging heat between a dilute absorbent flowing from an absorber to a regenerator and a concentrated absorbent returning from the regenerator to the absorber. The present invention relates to a device for detecting an abnormality of an absorption refrigerator to be detected.

[0002]

2. Description of the Related Art For example, Japanese Patent Application Laid-Open No. 28454/1988 discloses that an absorption chiller / heater is provided with a temperature detector, for example, in an evaporator and a pipe connecting each element. Diagnosis that determines whether the operation state of the machine is transient or stable, executes the refrigeration capacity diagnosis of the absorption chiller / heater based on the condition of the stable operation state, and displays the refrigeration capacity list based on the diagnosis result. An apparatus is disclosed.

[0003]

In the above prior art, when a decrease in the refrigerating capacity is diagnosed, it is necessary to determine, for example, the rare absorption flowing from the evaporator or the absorber to the regenerator. It is necessary to detect the temperature at the inlet and outlet for each component such as a solution heat exchanger that exchanges heat between the liquid and the concentrated absorbent returning to the absorber from the regenerator, and compare it with the design value when INPUT is 100%. . For this reason, when the absorption chiller is partially loaded or has almost no load, such as spring or autumn, except in summer, the abnormality cannot be accurately detected in the operation state, and the detection of the abnormality of the refrigerator is delayed or stopped. One absorption chiller / heater to detect abnormal spots
The problem of having to run 00% occurs.

[0004]

In order to solve the above-mentioned problems, the present invention provides a high-temperature regenerator 4, a condenser 7, an evaporator 1, an absorber 2, and a rare absorbing liquid flowing from the absorber 2 to the high-temperature regenerator 4. In the absorption refrigerator in which a high-temperature heat exchanger 10 for exchanging heat with the concentrated absorption liquid returning from the high-temperature regenerator 4 to the absorber 2 is connected by piping, the cold water inlet temperature and the outlet temperature of the evaporator 1 are detected respectively. The cold water temperature detectors 36 and 37 to be used, the rare absorption solution temperature detectors 38 and 39 for detecting the inlet temperature and the outlet temperature of the high temperature heat exchanger 10 for the rare absorbing solution, respectively, and the high temperature heat exchanger 10 for the rich absorbing solution. The chilled water load is calculated from the concentrated absorption liquid temperature detectors 40 and 41 that detect the inlet temperature and the outlet temperature, respectively, and the difference between the detected temperature of each chilled water temperature detection and the chilled water inlet / outlet temperature difference at 100% load. Rare absorbent temperature detector and concentrated absorbent temperature Out device from the detected temperature high-temperature heat exchanger 1
Calculate the actual logarithmic mean temperature difference between the diluted and concentrated absorbent at 0
Logarithmic temperature difference and actual logarithm
An abnormality detector 43 that outputs an abnormality signal by comparing the average temperature difference with the average temperature difference, and provides an abnormality detection device that reliably detects an abnormality of the high-temperature heat exchanger 10 even when the absorption refrigerator is partially loaded. It is.

Further, chilled water temperature detectors 36 and 37 for detecting a chilled water inlet temperature and an outlet temperature of the evaporator 1 respectively, and a dilute absorbent for detecting the inlet temperature and the outlet temperature of the dilute absorbent high temperature heat exchanger 10 respectively. Temperature detectors 38 and 39, concentrated absorbent temperature detectors 40 and 41 for detecting the inlet temperature and the outlet temperature of the concentrated absorbent high-temperature heat exchanger 10, respectively, and cooling for detecting the cooling water inlet temperature of the absorber 2. Water temperature detector 42
Then, the chilled water load is calculated from the difference between the detected temperatures of the chilled water temperature detectors and the chilled water inlet / outlet temperature difference at the time of a 100% load, and the diluted absorbent temperature detectors 38 and 39 and the concentrated absorbent temperature detector 40 are used. , 41, the actual logarithmic average temperature difference between the diluted absorption liquid and the concentrated absorption liquid in the high-temperature heat exchanger 10 is calculated, and the ideal temperature corresponding to the chilled water load based on the detected temperature of the cooling water temperature detector is calculated.
An abnormality detector 43 for comparing the logarithmic average temperature difference with the actual logarithmic average temperature difference and outputting an abnormality signal, and when the cooling water temperature changes at the partial load of the absorption refrigerator, the cooling water temperature It is an object of the present invention to provide an abnormality detection device that reliably detects an abnormality in the high-temperature heat exchanger 10 before the temperature changes.

[0006]

[0007]

When the absorption refrigerator is in operation, the abnormality detector 43 includes the cold water temperature detectors 36 and 37 and the machine absorption liquid temperature detectors 38 and 39.
And the temperature signals from the concentrated absorbent temperature detectors 40 and 41, and calculate the load from the chilled water inlet / outlet temperature difference at 100 load and the actual chilled water inlet / outlet temperature difference.
The actual logarithmic mean temperature difference of 0 is calculated. And this actual
Ideal logarithmic average for logarithmic average temperature difference corresponding to the load at that time
When the temperature exceeds the abnormal line determined by the temperature difference , the abnormality detector 43 outputs an abnormality signal to notify the abnormality of the high-temperature heat exchanger 10, so that the absorption refrigerator has a partial load in the spring other than the summer. In some cases, an abnormality can be detected, and maintenance and inspection work can be performed at an early stage for an abnormality in the high-temperature heat exchanger 10.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a schematic configuration diagram of an absorption chiller / heater which is an absorption refrigerator using, for example, water as a refrigerant and a lithium bromide (LiBr) solution as an absorption liquid (solution), wherein 1 is an evaporator, and 2 is an absorber. Reference numeral 3 denotes an evaporator absorber body (hereinafter, referred to as a lower body) containing the evaporator 1 and the absorber 2, 4 denotes a high-temperature regenerator equipped with, for example, a gas burner 5 and is heated by a high-temperature heat source, 6 denotes a low-temperature regenerator, 7 Is a condenser, 8 is a low temperature regenerator condenser body (hereinafter, referred to as an upper body) containing the low temperature regenerator 6 and the condenser 7, and 9 is a rare absorbing liquid collected from the absorber 2 to the high temperature regenerator 4 and low temperature. A low-temperature heat exchanger, which is a solution heat exchanger for exchanging heat with the concentrated absorbent flowing from the regenerator 6 to the absorber 2;
Is a solution heat exchanger for exchanging heat between the dilute absorbent flowing from the absorber 2 through the low-temperature heat exchanger 9 to the high-temperature regenerator 4 and the medium-density concentrated absorbent flowing from the high-temperature regenerator 4 to the low-temperature regenerator 6. A high-temperature heat exchanger, 11 to 15 are absorption liquid pipes, 16 is an absorption liquid pump, 17 and 18 are refrigerant pipes, 19 is a refrigerant circulation pipe, 20 is a refrigerant pump, and 23 is an evaporator heat exchanger 24 provided in the middle. Chilled water pipes, each of which is connected as shown in FIG.

Reference numeral 25 denotes a cooling water pipe, and an absorber heat exchanger 26 and a condenser heat exchanger 27 are provided in the cooling water pipe 25. 28 is a refrigerant bypass pipe connecting the refrigerant reservoir 29 of the evaporator 1 to the absorbent reservoir 30 of the absorber 2, 31 is an on-off valve, 32 is an absorbent bypass pipe connecting the absorbent pipe 12 and the absorber 2. , 33 is an on-off valve,
34 is a refrigerant vapor bypass pipe connecting the refrigerant pipe 17 and the absorber 2, and 35 is an on-off valve, and each of the on-off valves 31, 33,
35 is closed when supplying cold water and opened when supplying hot water.

Reference numerals 36 and 37 denote chilled water temperature detectors for detecting chilled water inlet and outlet temperatures of the evaporator 1, respectively.
Reference numeral 9 denotes a rare absorbent temperature detector which is provided on the inlet side and the outlet side of the high-temperature heat exchanger 10 of the absorbent pipe 11 and detects the temperature of the rare absorbent flowing from the absorber 2 to the high-temperature regenerator 4.
Reference numerals 0 and 41 denote a concentrated absorbent temperature which is provided in the absorbent pipes 12 and 13 on the inlet side and the outlet side of the high temperature heat exchanger 10 and detects the temperature of the intermediate concentrated absorbent flowing from the high temperature regenerator 4 to the low temperature regenerator 6, respectively. A detector 42 is a cooling water temperature detector provided in the cooling water pipe 25 on the inlet side of the absorber 2.

Reference numeral 43 denotes an abnormality detector for detecting an abnormality of the high-temperature heat exchanger 10 by inputting a temperature signal from each of the temperature detectors. The abnormality detector 43 is, for example, a control panel (shown in the drawing) of an absorption refrigerator. ) And is constituted by a microcomputer. An alarm device 44 is provided on the control panel similarly to the abnormality detector 43 and operates by inputting a signal from the abnormality detector. The notification device 44 includes, for example, a display device 45 having a plurality of segment elements and a buzzer 46. Then, the display device 45 blinks, for example, ALARM characters based on the signal from the abnormality detector 43.

Hereinafter, the configuration of the abnormality detector 43 will be described with reference to FIG.
It will be described based on. 47 is a cold water temperature detector 36, 3
7. Input interface for inputting signals from the rare absorbing solution temperature detectors 38 and 39 and the thick absorbing solution temperature detectors 40 and 41, converting the signals, and outputting the signals to a central processing unit (hereinafter referred to as CPU) 48. , 49 are storage devices (hereinafter referred to as ROM) storing operation programs and the like relating to the present invention;
Reference numeral 50 denotes an output interface for inputting a signal from the CPU 48 and outputting the signal to the notification device 44; 51, a signal generator (hereinafter, referred to as CLOOCK) for outputting a signal every predetermined time;
Reference numeral 52 denotes a readable and erasable storage device (hereinafter, referred to as a RAM) that stores the temperature detected by each temperature detector.

The ROM 49 stores a rare absorbing liquid inlet temperature T.
1. The logarithmic average temperature difference Tlm, which is the average value of the actual temperature difference of the high-temperature heat exchanger 10, is calculated from the diluted absorbent outlet temperature T2, the concentrated absorbent inlet temperature T3, and the concentrated absorbent outlet temperature T4.

[0014]

(Equation 1)

And 1 during normal operation of the absorption refrigerator.
A program for calculating the chilled water load from the difference between the chilled water inlet temperature and the chilled water outlet temperature at the time of the 00% load and the actually detected difference between the chilled water inlet temperature and the chilled water outlet temperature, and the chilled water load and the high-temperature heat exchange shown in FIG. The relationship with the logarithmic average temperature difference of the vessel 10 is stored. As shown in FIG. 3, the ROM 49 stores the chilled water load and the ideal load when the absorption chiller is operating normally .
An ideal line indicating the relationship with the number average temperature difference and an abnormal line that outputs an abnormal signal are stored for each cooling water temperature,
A plurality of ideal lines and abnormal lines are stored in addition to those shown in FIG. 3 with the cooling water temperature as a parameter.

During the operation of the absorption chiller for supplying cold water, the refrigerant evaporated in the high-temperature regenerator 4 flows to the condenser 7 through the low-temperature regenerator 6 as in the conventional absorption chiller, and the heat exchanger is connected to the condenser. After being condensed and liquefied by exchanging heat with the cooling water flowing through 27, it flows to the evaporator 1 via the refrigerant pipe 18. Then, the refrigerant exchanges heat with water flowing through the evaporator heat exchanger 24 to evaporate, and the water flowing through the evaporator heat exchanger 24 is cooled by heat of vaporization.
Then, cold water circulates through the load. Further, the refrigerant evaporated in the evaporator 1 is absorbed by the absorbing liquid in the absorber 2. The diluted absorption liquid whose concentration has been reduced by absorbing the refrigerant is sent to the high-temperature regenerator 4 through the low-temperature heat exchanger 9 and the high-temperature heat exchanger 10 by the operation of the absorption liquid pump 16. The absorbing liquid sent to the high-temperature regenerator 4 is heated by the burner 5 to evaporate the refrigerant, and the medium-density concentrated absorbing liquid flows through the high-temperature heat exchanger 10 to the low-temperature regenerator 6. In the low-temperature regenerator 6, the absorbing liquid is heated by the refrigerant vapor flowing from the high-temperature regenerator 10 through the refrigerant pipe 17, and the refrigerant vapor is further separated to increase the concentration. The concentrated absorbent having a high concentration passes through the low-temperature heat exchanger 9 and the temperature thereof is reduced.
Sent to and sprayed.

As described above, the abnormality detection when the absorption refrigerator is in operation will be described with reference to the flowchart of FIG. Chilled water temperature detectors 36 and 37, rare absorption liquid temperature detectors 38 and 39, concentrated absorption liquid temperature detectors 40 and 41
The respective temperatures detected by the cooling water temperature detector 42 are temporarily stored in the RAM 52 via the input interface 47 and the CPU 48. Then, based on the signal from the CLOCK 51, the cold water inlet temperature, the cold water outlet temperature, the rare absorbing solution temperature, the concentrated absorbing solution temperature, and the cooling water temperature stored in the RAM 52 at predetermined time intervals are read into the CPU 48.
The equation 1, the program, and the relationship between the chilled water load and the logarithmic average temperature difference are read from the OM 49. Then, the load (%) is calculated from the actual chilled water inlet / outlet temperature difference and the chilled water inlet / outlet temperature difference (5 ° C.) when the load is 100%. Here, for example, when the cold water inlet temperature is 10 ° C., the cold water outlet temperature is 7 ° C., and the temperature difference is 3 ° C., the load is 3/5 = 0.6 (6
0%).

The actual logarithmic average temperature difference Tlm is calculated by the CPU 48 from the temperature of the diluted absorbing solution, the temperature of the concentrated absorbing solution, the temperature of the cooling water, and the equation (1). Here, for example, the heat exchange performance of the high-temperature heat exchanger 10 is reduced due to a decrease in the flow rate of the absorbent in the heat exchanger due to contamination of the absorbent or generation of crystals, or a perforation in the heat exchanger. When the absorbing liquid inlet temperature is, for example, 45 ° C., the low-temperature absorbing liquid outlet temperature is, for example, 75 ° C., the high-temperature absorbing liquid inlet temperature is, for example, 95 ° C., and the high-temperature absorbing liquid outlet temperature is, for example, 60 ° C., the actual logarithmic average temperature difference is approximately 18 ° C. 0.7 ° C. Then, the cooling water temperature at this time is, for example, 30 ° C., and the actual logarithmic average temperature difference is the value (17.4 ° C.) when the cooling water temperature shown in FIG. ) Higher, CP
U48 outputs an abnormal signal through the output interface 50, and an abnormal signal is output from the abnormality detector 43 to the notification device 44. A is displayed on the display device 45 of the notification device 44.
LARM is displayed and the buzzer-46 sounds,
An abnormality of the absorber 2 is notified. Also, when the cold water load is, for example, 60%, the actual logarithmic average temperature difference Tlm calculated from the dilute absorbent inlet temperature, the dilute absorbent outlet temperature, the concentrated absorbent inlet temperature, the concentrated absorbent outlet temperature and the above equation (1). Is 1
When the temperature is 6.5 ° C. and is lower than the value (17.4 ° C.) on the abnormal line when the load is 60%, the CPU 48 does not output the abnormal signal, and the notifying device 44 does not notify the abnormality.

According to the above embodiment, the abnormality detector 43 determines the actual logarithm based on the dilute absorbing liquid inlet temperature, the dilute absorbing liquid outlet temperature, the concentrated absorbing liquid inlet temperature, the concentrated absorbing liquid outlet temperature and the equation (1). The average temperature difference is calculated, and the high-temperature heat exchanger 10 becomes abnormal, that is, the heat exchange efficiency decreases due to contamination of the absorbing solution or generation of crystals, and the actual logarithmic average temperature difference exceeds the abnormal line in which the temperature is stored in advance. If the error detector 4
3 outputs a signal. If an abnormality occurs in the high-temperature heat exchanger 10 even in the intermediate period other than the summer or winter, the abnormality is detected at the partial load of the absorption chiller / heater and the initial period of occurrence of the abnormality is detected. As a result, maintenance and inspection of the absorption chiller / heater can be performed more reliably.

Further, when the temperature of the cooling water flowing into the absorber 2 is kept substantially constant, it is not necessary to store the abnormal lines for each of the plurality of cooling water temperatures in the ROM 49, and the temperature is kept constant. What is necessary is just to memorize the abnormal line of the temperature of the cooling water dripping.

[0021]

Hereinafter, a second embodiment of the present invention will be described with reference to FIG. It should be noted that a configuration that is not particularly described is the same as the above-described embodiment, and a detailed description is omitted. Numerals 53 and 54 denote rare-absorbent temperature detectors provided on the inlet side and outlet side of the low-temperature heat exchanger 9 of the absorbent pipe 11, respectively, and 55 denote an absorbent pipe 14 on the inlet side of the low-temperature heat exchanger 9.
Reference numeral 56 denotes a concentrated absorbent temperature detector provided in the absorbent pipe 15 on the outlet side of the low-temperature heat exchanger 9. Then, the actual logarithmic average temperature difference is calculated based on the diluted absorption liquid inlet temperature, the diluted absorption liquid outlet temperature, the concentrated absorption liquid inlet temperature, and the concentrated absorption liquid outlet temperature detected by each temperature detector. Similar operation and effect can be obtained when the abnormality of the low-temperature heat exchanger 9 is determined by comparing with the abnormal line as in the embodiment.

Further, as shown in the above embodiment, the actual logarithmic average temperature difference or the average value of the temperature differences of the low temperature heat exchanger 9 or the high temperature heat exchanger 10 is obtained. Then, the logarithmic average temperature difference or the ratio of the cold water load to the average value of the temperature difference is calculated. For example, the chilled water load is 60%, the actual log average temperature difference is 18 ° C., and the ratio of the load to the log average temperature difference is 0.30 ° C./%. Abnormality detection device 4
The same operation and effect as in the above embodiment can be obtained also when the third unit outputs an abnormal signal.

Further, the ratio of the actual log average temperature difference or the average value of the temperature difference to the ideal log average temperature difference or the average value of the temperature difference is calculated. Then, when this ratio exceeds a predetermined value, the abnormality detector 43 outputs an abnormality signal. For example, the cooling water temperature is, for example, 30 ° C., the load is 60%, the actual log average temperature difference is 18 ° C., and the ideal log average temperature difference is 1
When the temperature is 4.4 ° C., the above ratio is 18 / 14.4 = 1.2.
The abnormality detector 43 outputs an abnormality signal when it is equal to or more than a predetermined value (for example, 1.20). Further, the actual heat transmission coefficient, which is the reciprocal of the above ratio, is calculated, and when the heat transmission coefficient becomes a predetermined value (for example, 80%) or less, the abnormality detector 43
The same operation and effect can also be obtained when an abnormal signal is output.

In the above embodiment, the abnormality detecting device for detecting an abnormality of the high-temperature heat exchanger 10 or the low-temperature heat exchanger 9 has been described.
The same operation and effect can be obtained when an abnormality detector for detecting both the 0 and the low-temperature heat exchanger 9 is provided in the absorption chiller / heater. In the above embodiment, the description has been given based on the absorption chiller / heater that can supply cold water or hot water. However, the absorption chiller that supplies only chilled water can also be provided by providing the abnormality detector in the same manner as in the above embodiment. The function and effect of can be obtained.

[0026]

According to the present invention, there is provided an abnormality detecting device for an absorption refrigerator configured as in the above embodiment, wherein the cold water inlet and outlet temperatures of an evaporator are detected by a cold water temperature detector, respectively. The cooling water inlet and outlet temperatures are detected by the cooling water temperature detector, and the diluted absorbent temperature at the inlet side and the outlet side of the solution heat exchanger are detected by the diluted absorbent temperature detector, and the inlet side of the solution heat exchanger is detected. And the temperature of the concentrated absorbent at the outlet side is detected by the concentrated absorbent temperature detector, and the abnormality detector calculates the chilled water load from the difference between the detected temperatures of the respective chilled water temperature detectors and the difference between the chilled water inlet and outlet temperatures at 100% load. And the actual logarithmic average of the solution heat exchanger based on the temperature detected by each of the diluted absorbent temperature detector and the concentrated absorbent temperature detector.
Calculate the temperature difference and calculate the ideal logarithmic average temperature difference for the cold water load.
And output an abnormal signal by comparing with the actual logarithmic average temperature difference
Therefore, the ideal logarithmic flat
For example, a simulation can be performed to determine the average temperature difference without actually performing experiments.
Can be easily calculated by
For example, abnormalities in the solution heat exchanger can be reliably detected even during a partial load in the interim period other than summer, and as a result, maintenance of the absorption chiller is carried out early to suspend the absorption chiller. Can be avoided.

The temperature of the cold water inlet and the outlet of the evaporator are detected by a cold water temperature detector, and the temperature of the diluted absorbent at the inlet and the outlet of the solution heat exchanger is detected by the diluted water temperature detector. The temperature of the concentrated absorbent at the inlet and outlet of the heat exchanger is detected by the concentrated liquid temperature detector, and the cooling water inlet of the absorber is detected by the cooling water temperature detector. Calculate the chilled water load from the difference between the detected temperature of the chilled water and the chilled water inlet / outlet temperature difference at the time of 100% load. Calculate the actual log average temperature difference between the absorption liquid and the concentrated absorption liquid, and compare the ideal log average temperature difference corresponding to the chilled water load based on the temperature detected by the cooling water temperature detector with the actual log average temperature difference <br By outputting an abnormal signal in comparison with the actual logarithmic average
Experiment to find the ideal logarithmic mean temperature difference to compare the temperature difference
Without actually doing it, for example by simulation
It can be easily calculated, and even if the temperature of the cooling water changes during operation of the absorption refrigerator, the abnormality of the solution heat exchanger can be accurately detected regardless of the temperature of the cooling water of the solution heat exchanger can do.

[0028]

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an absorption refrigerator showing one embodiment of the present invention.

FIG. 2 is a block diagram of an anomaly detector.

FIG. 3 is a relationship diagram between a load and a logarithmic average temperature difference.

FIG. 4 is a flowchart illustrating the operation of the abnormality detection device.

FIG. 5 is a schematic configuration diagram of an absorption refrigerator showing a second embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Evaporator 2 Absorber 4 High temperature regenerator 6 Low temperature regenerator 9 Low temperature heat exchanger 10 High temperature heat exchanger 36 Cold water temperature detector 37 Cold water temperature detector 38 Rare absorption liquid inlet temperature detector 39 Rare absorption liquid outlet temperature detector 40 Rich absorbent inlet temperature detector 41 Rich absorbent outlet temperature detector 42 Cooling water temperature detector 43 Abnormality detector

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-56-146966 (JP, A) JP-A-3-67966 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) F25B 15 / 00,49 / 04

Claims (2)

(57) [Claims] 1. A piping comprising a regenerator, a condenser, an evaporator, an absorber, and a solution heat exchanger for exchanging heat between a dilute absorbent flowing from the absorber to the regenerator and a concentrated absorbent returning from the regenerator to the absorber. In the absorption refrigerator connected, a chilled water temperature detector for detecting the chilled water inlet temperature and the outlet temperature of the evaporator, respectively,
A dilute absorbent temperature detector that detects the inlet temperature and the outlet temperature of the dilute absorbent solution heat exchanger, and a concentrated absorbent temperature detector that detects the inlet temperature and the outlet temperature of the concentrated absorbent solution heat exchanger, respectively. Calculate the chilled water load from the difference between the detected temperatures of the chilled water temperature detectors and the chilled water inlet / outlet temperature difference at 100% load. Calculate the actual logarithmic mean temperature difference between the dilute and concentrated absorbents in the solution heat exchanger, and
An abnormality detector for comparing an ideal log average temperature difference with an actual log average temperature difference and outputting an abnormality signal. 2. A piping including a regenerator, a condenser, an evaporator, an absorber, and a solution heat exchanger for exchanging heat between the dilute absorbent flowing from the absorber to the regenerator and the concentrated absorbent returning from the regenerator to the absorber. In the absorption refrigerator connected, a chilled water temperature detector for detecting the chilled water inlet temperature and the outlet temperature of the evaporator, respectively,
A dilute absorbent temperature detector that detects the inlet temperature and the outlet temperature of the dilute absorbent solution heat exchanger, and a concentrated absorbent temperature detector that detects the inlet temperature and the outlet temperature of the concentrated absorbent solution heat exchanger, respectively. And a cooling water temperature detector for detecting a cooling water inlet temperature of the absorber, a chilled water load is calculated from a difference between the detected temperatures of the chilled water temperature detectors and a chilled water inlet / outlet temperature difference at 100% load, and Calculate the actual logarithmic mean temperature difference between the rare and concentrated absorbents in the solution heat exchanger from the detected temperatures of the rare and concentrated absorbent temperature detectors , and calculate the detected temperature of the cooling water temperature detector. Logarithmic mean corresponding to the chilled water load at the plant
An abnormality detector for comparing the temperature difference with an actual logarithmic average temperature difference and outputting an abnormality signal;