JPH0791783A - Trouble diagnosing system for absorption chilled and warm water machine - Google Patents

Abstract

PURPOSE:To provide a trouble diagnosing system which can effectively detect an internal malfunction even at the time of a low load in an absorption chilled and warm water machine. CONSTITUTION:A concentration (concentrated liquid) of absorbent liquid to be scattered by an absorber, a coolant inlet temperature, a refrigerating load are detected based on various measured values by a sensor group. A concentrated liquid concentration characteristic calculator 74 of an arithmetic processor previously stores concentrated liquid concentration characteristics for representing a variation in the concentration at the time of a normal operation, and calculates the concentration (suitable concentrated liquid concentration) at the time of the normal operation based on the coolant temperature and a detected value of a refrigerating load. A malfunction degree detector 7 calculates a difference of the detected value of the concentration (evaluated concentrated liquid concentration) and a suitable concentrated liquid concentration, and a trouble diagnosing unit 76 prepares diagnosis data representing a malfunction degree based on the difference, and outputs it.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an absorption chiller-heater typified by an absorption chiller, and in particular, it is caused by various abnormalities based on the concentration of an absorption liquid, that is, a concentrated liquid sprayed in the absorber. The present invention relates to a failure diagnosis system that detects a decrease in driving ability.

[0002]

2. Description of the Related Art In an absorption chiller, a condenser, an evaporator, an absorber, a regenerator and the like are connected to each other by piping to form one refrigeration cycle. In particular, double-effect absorption chillers are widely used because of their high refrigeration efficiency (see, for example, JP-A-62-77567 [F25B15 / 00]).

FIG. 1 shows the structure of a double-effect type absorption refrigerator. The upper body (1) is composed of a condenser (11) and a low temperature regenerator (12), an evaporator (21) and an absorber. Lower body (2) consisting of (22),
High temperature regenerator (3) with built-in burner (31), high temperature heat exchanger
(4), the low temperature heat exchanger (5), etc. are connected to each other by piping.

In the absorption refrigerator, the cooling water becomes dirty,
In order to diagnose internal abnormalities of the refrigerator such as abnormal absorption liquid circulation volume and vacuum degree, logarithmic mean temperature difference Δ at the time of diagnosis for each heat exchange unit such as evaporator (21) and condenser (11)
From T and the logarithmic average temperature difference ΔTs during normal operation, an abnormality degree A defined by the following equation 1 is calculated and this abnormality degree is monitored.

[0005]

## EQU1 ## A = (ΔT−ΔTs) / ΔTs

By the way, in the absorption refrigerator, if any internal abnormality occurs, the refrigeration efficiency is lowered,
The concentration of the absorption liquid, that is, the concentrated liquid, which is sprayed by the absorber, increases. When the concentration of the concentrated liquid exceeds a certain value, it causes serious troubles such as crystallization of the absorbing liquid. Therefore, the absorption chiller is equipped with a safety device that monitors the concentration of the concentrated liquid and stops the operation of the refrigerator when the concentration of the concentrated liquid exceeds a certain value.

[0007]

However, the concentration of the concentrated liquid fluctuates depending on the refrigerating load and other operating conditions, and even if it shows a low value at a constant load, if the refrigerating load rapidly increases, As a result, the concentration of the concentrated liquid sharply rises and the operation is stopped. When the operation is suddenly stopped in this way, the refrigerator does not function at all even though the restoration period is a period when the load is high, which causes a serious problem. Here, even if the abnormality of the internal state is not predicted by monitoring the degree of abnormality described above, the rate of change of the degree of abnormality depends on the refrigeration load,
The change does not significantly appear in the low load state as compared with the high load state. Therefore, in the low load state, it is difficult to accurately detect the abnormality inside the refrigerator.

An object of the present invention is to provide a failure diagnosis system capable of accurately detecting an internal abnormality even when the load is low. Another object of the present invention is to provide a failure diagnosis system capable of quantitatively recognizing the operating margin regarding the concentration of concentrated liquid based on the detection of an internal abnormality and taking measures such as limiting the load. It is to be.

[0009]

A first failure diagnosis system for an absorption chiller-heater according to the present invention is provided for the concentration of the absorbing liquid (concentration of concentrated liquid) dispersed in the absorber and the cooling of the absorbing liquid. The detection means for detecting the temperature of the cooling water and the refrigeration load involved, and the concentration characteristic of the concentrated liquid representing the change of the concentrated liquid concentration during the normal operation with the cooling load as a variable and the cooling water temperature as a parameter are stored in advance. Based on the detected value of the cooling water temperature and the refrigeration load, the concentration derivation means for deriving the concentrated concentration of the normal operation (proper concentrated concentration) from the storage means, and the detected value of the concentrated concentration ( A diagnostic processing means is provided for calculating a difference between the evaluation concentrated liquid concentration) and the proper concentrated liquid concentration, and for producing and outputting diagnostic data indicating the degree of abnormality based on the concentration difference.

In addition to the detection means, the storage means, and the concentration derivation means, the second failure diagnosis system according to the present invention is further provided with a detection value of the concentration of concentrated liquid (evaluated concentration of concentrated liquid) and the proper concentration of concentrated liquid. Is calculated, and the concentration characteristic of the concentrated liquid stored in the storage means is shifted by the concentration difference to calculate the margin of the current driving capacity within the maximum allowable concentration of the concentrated liquid. It is equipped with a calculation means for performing.

In a concrete configuration, the calculating means obtains a change in the concentration of the concentrated liquid when the refrigeration load increases while the temperature of the cooling water is held at the detected value, based on the shifted characteristic of the concentration of the concentrated liquid. The upper limit value of the refrigerating load at which the concentrated concentration reaches the maximum allowable value is derived, and the upper limit value is used as the maximum operating capacity to calculate the margin of the current operating capacity.

[0012]

First, the principle of failure diagnosis of the absorption chiller-heater according to the present invention will be described with reference to FIGS. 3 and 4. Most abnormal states that occur in the absorption refrigerator such as abnormal vacuum degree and contamination of cooling water finally appear as a phenomenon in which the concentration of the absorbing liquid increases. Therefore, if the proper value of the concentration of the absorbing liquid in the normal operation state is known, the concentration of the absorbing liquid can be used as a monitoring parameter for the abnormal state. In particular, an increase in the concentration of the absorbing liquid (concentrated liquid concentrated liquid) sprayed in the absorber can be a direct cause of internal abnormalities such as the occurrence of crystals that cause operation stop. It is appropriate to use a concentration.

The appropriate value of the absorption liquid concentration depends on the refrigeration load and the cooling water temperature. FIG. 3 is a plot of the characteristics of changes in the concentration of the concentrated liquid when the refrigerator is operating normally, with the refrigeration load and the cooling water inlet temperature as parameters. As shown, if the cooling water inlet temperature is kept constant,
A unique functional relationship holds between the refrigeration load and the concentration of the concentrated liquid. Therefore, as shown in FIG. 4, a change in the concentration of the concentrated liquid in the normal operation state is shown in advance in a concentration characteristic curve using the refrigeration load as a variable and the cooling water inlet temperature as a parameter. Then, if the difference between the detected value of concentrated liquid concentration (evaluated concentrated liquid concentration) and the appropriate concentrated liquid concentration is calculated based on the characteristic curve, the magnitude of the concentration difference indicates the degree of internal abnormality.

Further, by shifting the concentrated liquid concentration characteristic of FIG. 4 by the concentration difference, the concentrated liquid concentration characteristic in the abnormal state can be obtained. For example, as shown by point P ′ in FIG. 4, the detected value of the concentrated liquid concentration (evaluated concentrated liquid concentration) when the refrigeration load is approximately 50% is 62%
Assuming that the cooling water inlet temperature is 28 ° C., the appropriate concentrated liquid concentration at that time is about 58% as indicated by the point P. Therefore, only the difference dDs between the evaluation concentrated liquid concentration and the proper concentrated liquid concentration is 28
The concentration characteristic curve P-Q at the temperature of ° C is shifted to obtain the characteristic curve P'-Q 'in the abnormal state. Then, the refrigerating load Lc_e at the point Q'where the characteristic curve P'-Q 'intersects with the level of the maximum permissible value of concentration of concentrated liquid (operating permissible limit concentration) Ds_max is changed to the operating capacity limit value in the abnormal state. Set to. Therefore, the driving capacity limit value Lc_e
And the difference dLc between the detection value Lc of the refrigeration load and the refrigeration load represent the margin of the operating capacity.

The failure diagnosis system according to the present invention is derived from the above consideration. In the first failure diagnosis system, the concentration and concentration, the cooling water temperature, and the refrigeration load are directly measured by various sensors and estimation calculations. Measured or calculated by estimation. The concentrated liquid concentration characteristic as shown in FIG. 4 is stored in the storage means as a function, and the concentrated liquid concentration (adequate concentrated liquid concentration) Ds_n during normal operation is stored based on the detected values of the cooling water temperature and the refrigeration load. Is derived. Then, the difference dDs between the detected value of concentrated liquid concentration (evaluated concentrated liquid concentration) Ds_m and the proper concentrated liquid concentration Ds_n is calculated, and diagnostic data indicating the degree of abnormality, for example, “normal”, is calculated according to the magnitude of the concentration difference.
An "abnormal" or "abnormal" is created.

Further, in the second failure diagnosis system, the concentrated liquid concentration characteristic in the abnormal state is created by further shifting the concentrated liquid concentration characteristic of FIG. 4 by the concentration difference dDs, and based on this, the concentrated liquid concentration characteristic is created. The margin of the current driving capacity within the maximum allowable liquid concentration is calculated.

[0017]

According to the failure diagnosing system for the absorption chiller-heater according to the present invention, the internal abnormality can be accurately detected based on the difference between the normal value and the detected value of the concentrated concentration even when the load is low. To be done. In addition, since the operation margin regarding the concentration of concentrated liquid is quantitatively recognized based on the detection of internal abnormality, when abnormalities occur, measures such as limiting the load can be taken to stop the chiller-heater abnormally. It can be avoided.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An example in which the present invention is applied to a double-effect absorption refrigerator is described below in detail with reference to the drawings. As shown in FIG. 1, the absorption refrigerator uses water as a refrigerant and lithium bromide (LiBr) solution as an absorption liquid, and a condenser (11)
And an upper body (1) including a low temperature regenerator (12), a lower body (2) including an evaporator (21) and an absorber (22), a high temperature regenerator (3) including a burner (31), and high temperature heat The exchanger (4), the low temperature heat exchanger (5) and the like are connected to each other by piping. In addition, necessary sensors (not shown) are installed in the medium input / output unit of these multiple devices.
Is attached, and various physical quantities described later are measured.

Cooling water having a low temperature supplied from a cooling tower (not shown) first passes through the absorber (22) and then
The cooling water, which has passed through the condenser (11) and the temperature of which has risen, is returned to the cooling tower again. Further, cold water having a high temperature from the indoor unit (not shown) passes through the evaporator (21), and cold water having a low temperature cooled by this is supplied to the indoor unit.

FIG. 2 shows the configuration of the failure diagnosis system according to the present invention. The sensor group (6) is a low temperature regenerator (12).
Temperature Ts_hi, condensation temperature Tv_con of the condenser (11)
d, cooling water inlet temperature Tco_in of the absorber (22), cooling water intermediate temperature Tco_mid, cooling water outlet temperature Tco_ou
t, a cold water outlet temperature Tc_out of the evaporator (21), a cold water inlet temperature Tc_in, a cold water flow rate Vc, and the like, respectively, and a pressure gauge, a thermometer, and a flow meter are provided.

The arithmetic processing circuit (7) is composed of a microcomputer, and in addition to the four calculation units (71), (72), (74) and (77), the estimation unit (73), the detection unit (75) and the diagnosis unit ( 76). The concentrated liquid concentration estimation unit (73) determines the low temperature regenerator temperature Ts_hi.
And the condensing temperature Tv_cond, the estimated value Ds (%) of the concentrated liquid concentration is calculated based on the following equation 2. still,
The calculation formula is an empirical formula and is known as an accurate estimation formula.

[0022]

[Formula 2] Ds = (Ts_hi + 280.0) × 139.0 / (Tv_cond + 273.0) −102.4

The refrigerating load calculating unit (71) calculates the refrigerating load Lc from the cold water flow rate Vc, the cold water outlet temperature Tc_out and the cold water inlet temperature Tc_in based on the following equation 3.

## EQU3 ## Lc = Vc (Tc_in-Tc_out)

As shown in FIG. 4, the normal concentrated liquid concentration characteristic calculation unit (74) has a plurality of different cooling water inlets each having a concentrated liquid concentration curve representing a change in the concentrated liquid concentration during normal operation with the refrigeration load as a variable. The function is stored with the temperature as a parameter. The following expression 4 is a quadratic approximation of the concentrated liquid concentration curve at a specific cooling water inlet temperature.

[0025]

## EQU4 ## Ds = a × Lc ² + b × Lc + c Here, the constants a, b and c are determined by applying the least squares method to the actual measurement values shown in the graph of FIG.

The concentrated liquid concentration characteristic calculation unit (74) includes a refrigeration load Lc sent from the refrigeration load calculation unit (71) and a sensor group.
Based on the cooling water inlet temperature Tco_in sent from (6), the concentration of concentrated liquid during normal operation is calculated. At this time, for the cooling water inlet temperature which is not included in the parameters, an accurate concentrated liquid concentration is calculated by the interpolation process.

The abnormality level detection unit (75) uses the estimated value Ds of the concentrated liquid concentration as an evaluation concentrated liquid concentration Ds_m and the calculated value of the concentrated liquid concentration characteristic calculation unit (74) as an appropriate concentrated liquid concentration Ds_n, Based on Equation 5, the density difference dDs between the two is calculated.

[0028]

## EQU00005 ## dDs = Ds_m-Ds_n

Then, diagnostic data is created as follows according to the magnitude of the density difference dDs, and is displayed or printed out as necessary. dDs <t1: “normal” t1 <dDs <t2: “slightly abnormal” t2 <dDs: “abnormal” where t1 and t2 are preset constants.

Further, the operation allowance calculation unit (77) shifts the concentrated liquid concentration characteristic shown by the solid line in FIG. 4 by the above-mentioned concentration difference dDs, and the concentrated liquid at the time of abnormality occurrence is shown as a part of it by the chain line. Create concentration characteristics. That is, the concentration difference dDs is added to the concentration characteristic curve of the concentrated liquid expressed by the equation 4 to obtain a concentrated concentration curve of the following equation 6.

[0031]

## EQU6 ## Ds' = a × Lc ² + b × Lc + c + dDs

The operation allowance calculator (77) determines that the concentration value of the concentrated liquid calculated by the equation 6 is the operation allowable limit concentration Ds_max.
The refrigerating load Lc_e that reaches the limit is calculated, and if necessary, this value Lc_e or the operating capacity limit value L
The difference dLc from c_e is output as the driving margin.

The refrigeration load limit value Lc_e obtained from the operation allowance calculation unit (77) is sent to the gas inlet amount control unit (8),
The limit value Lc_e and the rated value Lc_max of the refrigeration load
Then, the maximum value Gas of the gas amount is determined from the rated value Gas_max of the gas amount based on the following equation 7.

[0034]

## EQU00007 ## Gas <Gas_max × Lc_e / Lc_max

The amount of gas entering the burner (31) of the high temperature regenerator (3) is limited based on this value Gas. Therefore, even if the refrigeration load requested from the outside exceeds the limit value Lc_e, the output of the refrigerator is limited to the limit value Lc_e, and the concentrated concentration does not reach the operation allowable limit concentration Ds_max.

Further, in the arithmetic processing circuit (7) of FIG.
Various failure diagnosis index calculation units (72) are provided, and data serving as an index for failure diagnosis, such as the above-mentioned abnormality degree A, is calculated based on various measurements sent from the sensor group (6). . These indexes are sent to the failure diagnosis section (76), and are subjected to failure diagnosis together with the concentrated liquid concentration difference dDs between the normal state and the abnormal state. As a result, the cause of the abnormal increase in the concentration of the concentrated liquid, for example, the abnormal vacuum, the contamination of the cooling water, the mixing of the absorbing liquid with the refrigerant, etc. will be investigated.

As described above, according to the failure diagnosis system of the present invention, the internal abnormality can be accurately detected based on the concentrated liquid concentration difference dDs between the normal state and the abnormal state even when the load is low.
Further, since the operational margin is quantitatively recognized based on the detection of the internal abnormality, when the abnormality occurs, the load can be limited to prevent the abnormal stop of the refrigerator. Furthermore, by combining the concentration difference dDs of the concentrated liquid with other indexes such as the degree of abnormality, it is possible to perform more advanced failure diagnosis.

The above description of the embodiments is for explaining the present invention, and should not be construed as limiting the invention described in the claims or reducing the scope. The configuration of each part of the present invention is not limited to the above-mentioned embodiment, and it goes without saying that various modifications can be made within the technical scope described in the claims. For example, when expressing the concentration characteristic of concentrated liquid shown in FIG. 3, it is possible to adopt not only the cooling water inlet temperature but also the cooling water intermediate temperature or the cooling water outlet temperature as a parameter.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an absorption refrigerator according to the present invention.

FIG. 2 is a block diagram of a failure diagnosis system according to the present invention.

FIG. 3 is a graph in which measured values of concentrated liquid concentration are plotted with the cooling water inlet temperature and the refrigeration load as parameters.

FIG. 4 is a graph in which the concentration characteristic of the concentrated liquid is made into a function.

[Explanation of symbols]

 (1) Upper body (11) Condenser (12) Low temperature regenerator (2) Lower body (21) Evaporator (22) Absorber (3) High temperature regenerator (6) Sensor group (7) Arithmetic processing circuit (8) ) Gas charge control unit

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yoshio Ozawa 2-18 Keihanhondori, Moriguchi-shi, Osaka Sanyo Electric Co., Ltd. (72) Inventor Masahiro Furukawa 2-18th Keihanhondori, Moriguchi-shi, Osaka Sanyo Denki Incorporated (72) Inventor Yasushi Kamata 2-18 Keihan Hondori, Moriguchi City, Osaka Sanyo Electric Co., Ltd.

Claims (3)

[Claims] 1. A detection means for detecting the concentration of the absorbing liquid (concentrated liquid concentrated liquid) dispersed in the absorber, the temperature of cooling water involved in cooling the absorbing liquid, and the refrigerating load, and the refrigerating load and cooling. Using the water temperature as a variable, the concentrated liquid concentration characteristics that represent changes in the concentrated liquid concentration during normal operation are stored in advance and stored in the storage device based on the detected values of the cooling water temperature and the refrigeration load. Concentration deriving means for deriving the concentration of concentrated liquid during operation (proper concentration of concentrated liquid), calculating the difference between the detected value of concentration of concentrated liquid (evaluated concentration of concentrated liquid) and the appropriate concentration of concentrated liquid, and based on the difference in concentration. And a diagnostic processing means for producing and outputting diagnostic data representing the degree of abnormality, and a failure diagnostic system for an absorption chiller-heater. 2. A detection means for detecting the concentration of the absorbing liquid (concentrated liquid concentrated liquid) dispersed in the absorber, the temperature of cooling water involved in cooling the absorbing liquid, and the refrigerating load, and the refrigerating load as a variable. , The concentration means for expressing the concentration of the concentrated liquid in the normal operation using the cooling water temperature as a parameter is stored in advance, and the storage means is based on the detected values of the cooling water temperature and the refrigerating load. Concentration deriving means for deriving the concentration of concentrated liquid during normal operation (appropriate concentration of concentrated liquid), calculating the difference between the detected value of concentrated concentration (evaluated concentration of concentrated liquid) and the appropriate concentration of concentrated liquid, and calculating the concentration difference The absorption-type cold temperature including a calculation means for calculating the margin of the current operating capacity within the maximum allowable value of the concentrated concentration by shifting the concentrated concentration characteristic stored in the storage means. Water machine failure diagnosis system. 3. The calculating means obtains, based on the shifted concentrated liquid concentration characteristic, a change in the concentrated liquid concentration when the refrigeration load increases while the cooling water temperature is held at the detected value, and the concentrated liquid concentration is changed. The fault diagnosis system according to claim 2, wherein an upper limit value of the refrigerating load at which the concentration reaches the maximum allowable value is derived, and a margin of the current operating capacity with the upper limit value as the maximum operating capacity is calculated.