JPH07198224A - Absorption type refrigerating machine - Google Patents

Abstract

PURPOSE:To continue a safety operation of an absorption type refrigerating machine by calculating and judging the degree of fouling of a cooling water system of a condenser to automatically control the heating amount of a refriger ant vapor generator. CONSTITUTION:Temperature data of various points are input from temperature sensors 31-35 to a controller, and the controller calculates and Judges the degree of fouling of a cooling water system against the refrigerating load at present. Then, a valve lift signal changed from the preset maximum valve lift is input to a fuel control valve 21, and furthermore, a valve lift signal by which the present valve lift is reduced by a specified ratio is output to the fuel control valve 21 when the degree of fouling of the cooling water system against the refrigerating load is already a specified value or higher. Thereby, a sudden shutdown of an absorption type refrigerating machine caused by a rise in pressure or temperature of a refrigerant vapor generator (high temperature regenerator) 1 can be prevented and safety operation of the refrigerating machine came be continued.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an absorption refrigerator having a generator that heats an absorbing liquid to generate a refrigerant vapor. Furthermore, the present invention relates to an absorption refrigerating machine in which the degree of fouling of the cooling water system of the condenser is calculated and judged, and the heating amount in the generator is automatically controlled, so that the operation can be safely continued.

[0002]

2. Description of the Related Art In conventional absorption refrigerators, various methods are used for predicting contamination of the cooling water system. However, these prior arts have been limited to the prediction and display of the contamination of the cooling water system, and have not been automatically controlled to continue safe operation of the machine.

[0003]

In the above prior art, when the absorption chiller is operated after starting, the cooling water system of the condenser becomes dirty, so that the heat exchange amount of the condenser is decreased and the internal pressure of the condenser is increased. To do. As the internal pressure of the condenser rises, so does the pressure and temperature of the generator. Then, when the pressure or temperature rises to reach the set value, a safety device generally provided in the absorption refrigerator operates, and the absorption refrigerator stops.

As a matter of course, if the absorption refrigerator is repaired, the inside of the cooling water pipe is washed, and the dirt is removed, the operation becomes possible. However, if the absorption chiller needs to be operated, for example, when the cooling operation is required most in the midsummer, if the operation is suddenly stopped, the user will be very troubled. In this case, even if the cooling capacity is reduced, the operation will continue within a safe range, and if maintenance and repair can be planned on days that do not require the operation of the absorption chiller, such as on holidays or off-season, the user will be advised. Is convenient.

An object of the present invention is to prevent the absorption refrigerating machine from suddenly stopping due to a rise in the pressure or temperature of the generator, to control the absorption refrigerating machine in a safe operating state, and to continue its operation. And

[0006]

In order to solve the above problems, the present invention provides a temperature sensor for detecting the outlet temperature of cooling water from a condenser, and a temperature sensor for detecting the temperature of a refrigerant condensed in the condenser. , The signals from these temperature sensors are input to calculate and determine the degree of fouling of the cooling water system, and at least depending on the degree of fouling of the cooling water system, an opening signal for changing the set value of the maximum valve opening of the fuel control valve is sent to the fuel control valve. Or a controller that outputs an opening signal to the fuel control valve to decrease the current valve opening by a predetermined ratio when the degree of contamination of the cooling water system is equal to or greater than a predetermined value.

Further, a temperature sensor for detecting the cooling water inlet and outlet temperatures of the condenser, a temperature sensor for detecting the temperature of the refrigerant condensed in the condenser, and a logarithm of the condenser by inputting signals from these temperature sensors. The air temperature difference is calculated, and the degree of fouling of the cooling water system is calculated and judged based on this logarithmic temperature difference and the refrigeration load, and at least the set value of the maximum valve opening of the fuel control valve is changed according to the degree of fouling of the cooling water system. A control device that outputs an opening signal to the fuel control valve, or outputs an opening signal to the fuel control valve to reduce the current valve opening by a predetermined ratio when the degree of contamination of the cooling water system is a predetermined value or more. Prepared.

[0008]

In the present invention, the temperature data of each part is input from the temperature sensor by the control device, the degree of contamination of the cooling water system with respect to the current refrigeration load is calculated and judged, and the maximum valve opening degree is set in advance in the fuel control valve. Value change opening signal, or
When the degree of contamination of the cooling water system with respect to the refrigerating load has already reached a predetermined value or more, an opening signal for decreasing the current valve opening by a predetermined rate is output to the fuel control valve 21. Therefore, both limit the amount of fuel supply to the generator of the absorption refrigerator, keep the rise of the pressure and temperature of the generator within the set value, the safety device operates and the absorption refrigerator stops. It is possible to prevent it.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the drawings. What is shown in the drawing is a double-effect absorption refrigerator, in which water (H ₂ O) is used as the refrigerant and lithium bromide (LiBr) aqueous solution is used as the absorption liquid.

In the drawings, 1 is a high temperature regenerator (generator) equipped with a gas burner 1B, 2 is a low temperature regenerator, 3 is a condenser, 4 is an evaporator, 5 is an absorber, 6 is a low temperature heat exchanger, and 7 Is a high temperature heat exchanger, 8 to 12 is an absorption liquid pipe, 15 is an absorption liquid pump, 16 to 18 is a refrigerant pipe, 19 is a refrigerant pump, 20 is a gas pipe connected to the gas burner 1B,
Reference numeral 21 is a fuel control valve, 22 is a cold water pipe, and each pipe is connected as shown in FIG. Further, 25 is a cooling water pipe, and an absorber heat exchanger 26 and a condenser heat exchanger 27 are provided in the middle of the cooling water pipe 25.

Further, 30 is a control unit for the absorption refrigerator, which is composed of a microcomputer, 31 is a temperature sensor for detecting the outlet temperature of the cooling water from the condenser 3, and 32 is a refrigerant which is cooled in the condenser 3 and condensed. The temperature sensor for detecting the temperature at the refrigerant pipe 17, 33 and 34 are the evaporator 4 respectively.
It is a temperature sensor that detects the temperature at the inlet and outlet of cold water cooled by. These temperature sensors 31 to 34 are connected to the control device 30. Also, the fuel control valve 21
Also, the valve opening degree can be controlled by being connected to the control device 30 and using an opening degree signal output from the control device 30.

The controller 30 has at least the following functions. That is, the temperature data of each part from the temperature sensors 31 to 34 are input, the degree of contamination of the cooling water system is calculated, and the fuel control valve 21 is operated so that the operation can be continued in a safe range. An opening signal for controlling the valve opening is output.

This will be described separately. First, the refrigeration load at that time is calculated from the temperatures of the inlet and outlet of the cold water input from the temperature sensors 33 and 34. Secondly, with the inputs from the temperature sensors 31 and 32, the difference between the refrigerant liquid temperature of the condenser 3 and the cooling water outlet temperature is calculated, and the degree of contamination of the cooling water system with respect to the refrigeration load is calculated. Thirdly, the calculated degree of contamination of the cooling water system is compared and judged with data given in advance, and an opening signal for controlling the opening degree of the valve is output to the fuel control valve 21.

There are two methods for outputting this opening signal. One is to change the maximum value of the valve opening of the fuel control valve 21 to a smaller one depending on the degree of contamination of the cooling water system. This is an operating condition where the refrigeration load is small and the valve opening is small at present, but there is a margin, but by installing the maximum valve opening in advance, safe operation when the refrigeration load increases It is something to try to secure.

The other is to judge the degree of fouling of the cooling water system and, when the degree of fouling exceeds a predetermined value, output an opening degree signal so as to reduce the current valve opening degree by a predetermined rate. It is a thing. This is effective when the ratio of the refrigerating load to the refrigerating capacity of the absorption refrigerator is already large.

The flow of the refrigerant and the absorbing liquid during the operation of the absorption refrigerator is the same as that of the conventional absorption refrigerator. That is, the refrigerant heated and evaporated in the high temperature regenerator (generator) 1 flows to the condenser 3 via the low temperature regenerator 2 and exchanges heat with the cooling water flowing in the condenser heat exchanger 27 to be condensed and liquefied. After that, it flows to the evaporator 4 through the refrigerant pipe 17. And
The refrigerant exchanges heat with the water in the cold water pipe 22 and evaporates, and the water in the cold water pipe 22 is cooled by the heat of vaporization. Cooled cold water is circulated to the load to perform cooling operation.

The refrigerant evaporated in the evaporator 4 is absorbed by the absorber 5.
And is absorbed by the absorbent. Then, the absorption liquid that has absorbed the refrigerant and becomes thin in concentration is sent to the high temperature regenerator (generator) 1 through the low temperature heat exchanger 6 and the high temperature heat exchanger 7 by the operation of the absorption liquid pump 15. The absorbing liquid that has entered the high temperature regenerator (generator) 1 is heated by the gas burner 1B, the refrigerant evaporates, and the medium concentration absorbing liquid enters the low temperature regenerator 2 through the high temperature heat exchanger 7. And the absorbing liquid is a high temperature regenerator (generator)
It is heated by the refrigerant vapor flowing from the refrigerant pipe 16 from 1, and the refrigerant is evaporated and separated to have a high concentration. The high-concentration absorbing liquid (hereinafter, referred to as a concentrated liquid) is sent to the absorber 5 after being lowered in temperature through the low temperature heat exchanger 6 and sprayed.

When the absorption refrigerator is operated as described above, the control device 30 inputs a temperature signal from the chilled water outlet temperature sensor 34, and outputs an opening signal preset according to the chilled water outlet temperature to the fuel control valve. It outputs to 21. Then, the opening degree of the fuel control valve 21 changes according to the cold water outlet temperature, and the amount of refrigerant vapor generated in the high temperature regenerator (generator) 1 changes. Then, the cold water outlet temperature is maintained at a substantially set temperature.

Further, when the absorption refrigerator is operated,
Cooling water circulates in the cooling water pipe 25. Then, dirt components (scale, slime, corrosion products, etc.) contained in the cooling water adhere to the inner surface of the condenser heat exchanger 27. Due to the adhesion of the dirt component, heat transfer from the refrigerant vapor in the condenser 3 to the cooling water is hindered, and the pressure in the condenser 3 rises. Then, as the pressure inside the condenser 3 rises, the pressure inside the high temperature regenerator (generator) 1 and the regeneration temperature rise.

Further, when the pressure inside the condenser 3 rises, the condensing temperature of the refrigerant rises, so that the temperature of the refrigerant liquid which condenses and accumulates below also rises. On the other hand, in the case of the cooling water, when the condenser 3 becomes dirty and the heat transfer capacity is reduced, the temperature rise in the condenser 3 will be small if the amount of cooling water is constant, so the cooling water outlet temperature will be low. As a result, as the cooling water system becomes more dirty, the difference between the refrigerant liquid temperature of the condenser 3 and the cooling water outlet temperature becomes larger for the same refrigeration load amount.

The refrigerating load of the absorption refrigerator is the amount of heat per unit time for cooling the cold water in the evaporator 4. Therefore, if the amount of cold water flowing through the cold water pipe 22 per unit time and the temperatures of the inlet and outlet of the cold water passing through the evaporator 4 are detected,
The refrigeration load can be calculated. If the cold water flow rate is constant, the refrigeration load can be calculated by inputting the cold water flow rate in advance and detecting only the temperatures of the cold water inlet and outlet. If the refrigerant liquid temperature of the condenser 3 and the cooling water outlet temperature are detected with respect to the refrigeration load, the difference can be calculated and the degree of contamination of the cooling water system can be calculated.

FIG. 2 shows the relationship between the refrigerating load (%) when a predetermined amount of cooling water is flowing in one absorption refrigerator, and the difference (° C.) between the refrigerant liquid temperature of the condenser and the cooling water outlet temperature. It is an example figure. In this figure, the straight line (A) shows the relationship when there is no stain. Even with the same refrigeration load, the temperature difference increases as the cooling water system becomes dirty and becomes larger. Caution (B)
In the range of, it is necessary to pay attention to the degree of contamination of the cooling water system.
In the abnormal (C) range, it is dangerous to operate as it is and some measures are required.

In FIG. 2, the temperature difference is 3.5 ° C. when the refrigeration load is 100% and there is no stain. The cooling water system is getting dirty,
The degree of contamination of the cooling water when the temperature difference rises to 4.9 ° C. is 40%, calculated as follows. Cooling water contamination degree = (4.9−3.5) ÷ 3.5 = 0.4

FIG. 3 is related to FIG. 2, and the degree of contamination of the cooling water system (%) and the maximum heat input (%) to be regulated (= maximum heating amount in the generator due to regulation of the valve opening of the fuel control valve 21) ) Is an example diagram showing a relationship with FIG. Refrigeration load 1 calculated from FIG.
In the case of 00% and the degree of cooling water contamination of 40%, in FIG.
It indicates that the maximum heat input (maximum heating amount) should be limited to 95%.

As another method of outputting an opening signal for controlling the opening of the fuel control valve 21, a temperature sensor 35 provided to measure the temperature of the cooling water flowing into the condenser 3, The controller 30 calculates the logarithmic average temperature difference of the condenser 3 based on the temperature data from the temperature sensors 31 and 32, calculates the degree of contamination of the cooling water system based on the logarithmic average temperature difference and the refrigeration load, and A method of outputting an opening degree signal for controlling the valve opening degree to the fuel control valve 21 can be adopted so that the operation can be continued in various ranges.

Also in this case, as described above, the control method in which the maximum value of the valve opening degree of the fuel control valve 21 is changed to a smaller one depending on the degree of contamination of the cooling water system, and the degree of contamination exceeds a predetermined value. In this case, there are two control methods, that is, a control method of outputting an opening signal so as to reduce the current valve opening by a predetermined ratio, and each has the same characteristics as described above.

In FIG. 5, when the refrigerant temperature measured by the temperature sensor 32 is T32 and the cooling water temperatures measured by the temperature sensors 31 and 35 are T31 and T35, ΔTlm = {(T32-T35)-(T32-T31 )} ÷ ln {(T32-T35) ÷
(T32-T31)} as the logarithmic average temperature difference ΔT in the condenser 3
It is a relationship diagram between lm and a refrigeration load.

As can be seen from FIG. 5, since the logarithmic mean temperature difference is obtained, the degree of contamination of the cooling water can be determined more accurately than in the case of FIG.

The control device 30 inputs the temperature data of each part from the temperature sensors 31 to 35, performs the above calculation, and sets the maximum valve opening value to the fuel control valve 21 according to the degree of contamination of the cooling water system. An opening signal for changing or changing the current valve opening is output. The calculation, the determination of the degree of contamination of the cooling water system, the instruction standard for changing the valve opening degree for the determination, and the like are set according to the capacity and specifications of the absorption refrigerator.

Although the above-described embodiment is a double-effect absorption refrigerator, the present invention can be applied to a single-effect absorption refrigerator and other absorption refrigerators. Since the function of the control device 30 describes the function necessary for the present invention, other functions, for example, the function of detecting the chilled water outlet temperature or the cooling air temperature and controlling the valve opening degree of the fuel control valve. There is no inconvenience even if it has a function of issuing a warning signal according to the degree of contamination of the cooling water system.

[0031]

The present invention is an absorption refrigerating machine configured as described above, and the control device 30 inputs temperature data of each part from temperature sensors 31 to 35 to obtain the present refrigerating load and refrigerating load. The degree of contamination of the cooling water system is calculated to determine the degree of contamination of the cooling water system, and the fuel control valve 2
Opening signal for changing the set value of the maximum valve opening in advance to 1.
Alternatively, when the degree of contamination of the cooling water system with respect to the refrigeration load has reached a predetermined value or more, an opening signal for decreasing the current valve opening by a predetermined rate is output to the fuel control valve 21.

As a result, one of the operating conditions is that the refrigeration load is small and the valve opening is small at the present time.
By changing the maximum valve opening degree to the smaller one in advance, it is possible to ensure the continuation of safe driving when the refrigeration load increases. Second, when the degree of contamination of the cooling water system has already reached a predetermined value or more, the current valve opening degree is immediately reduced by a predetermined rate, so that it is possible to ensure continued operation by safe operation.

In both cases, the growth of the contamination of the cooling water system is not known, and the contamination of the cooling water system raises the pressure and temperature of the generator to a set value, whereby the absorption refrigerator is provided. It is possible to prevent the user from being inconvenienced by the safety device being activated and the absorption refrigerator being stopped suddenly.

In particular, the method of controlling by obtaining the logarithmic mean temperature difference in the condenser is more accurate than the method of simply obtaining and controlling the temperature difference of each part to determine the degree of contamination of the cooling water system more accurately and the absorption refrigerator. The operation of can be continued stably.

Therefore, the user of the absorption refrigerating machine according to the present invention can experience the deterioration of the refrigerating capacity of the absorption refrigerating machine and systematically perform maintenance / repair of the absorption refrigerating machine during off season or on holidays. it can.

[Brief description of drawings]

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

FIG. 2 is a graph showing an example of the relationship between the refrigeration load (%) and the difference (° C.) between the refrigerant liquid temperature of the condenser and the cooling water outlet temperature for the absorption refrigerator.

FIG. 3 is a graph showing a relationship between the degree of cooling water system contamination (%) and the maximum heat input (%) to be regulated, in relation to FIG. 2.

FIG. 4 is a graph showing an example of the relationship between the refrigerant temperature (T32) and the cooling water temperature (T31, T35) at the inlet and outlet of the condenser.

FIG. 5 is a graph showing an example of the relationship between the refrigeration load (%) and the logarithmic average temperature difference (ΔTlm) in the condenser.

[Explanation of symbols]

1 High Temperature Regenerator (Generator) 3 Condenser 5 Absorber 21 Fuel Control Valve 30 Control Device 31 Temperature Sensor (Detects Cooling Water Outlet Temperature from Condenser) 32 Temperature Sensor (Refers to Temperature of Refrigerant Condensed in Condenser) 35 temperature sensor (detects the cooling water outlet temperature entering the condenser)

Claims (4)

[Claims] 1. An absorption refrigerating machine equipped with a generator for heating an absorbing liquid sent from an absorber to generate a refrigerant vapor, and a temperature sensor for detecting a cooling water outlet temperature from the condenser, and a condenser. The temperature sensors that detect the temperature of the refrigerant condensed in step 1 and the signals from these temperature sensors are input to calculate and determine the degree of contamination of the cooling water system, and the maximum valve opening of the fuel control valve is set according to the degree of contamination of the cooling water system. An absorption chiller comprising: a control device that outputs an opening signal for changing a value to a fuel control valve. 2. An absorption refrigerating machine equipped with a generator for heating an absorbing liquid sent from an absorber to generate a refrigerant vapor, and a temperature sensor for detecting a cooling water outlet temperature from the condenser, and a condenser. In the temperature sensor that detects the temperature of the condensed refrigerant in, the signal from these temperature sensors is input to calculate and determine the degree of contamination of the cooling water system, and if the degree of contamination of the cooling water system is greater than or equal to a predetermined value, the current An absorption refrigerating machine, comprising: a control device that outputs an opening degree signal for reducing a valve opening degree by a predetermined ratio to a fuel control valve. 3. An absorption refrigerating machine equipped with a generator for heating an absorption liquid sent from an absorber to generate a refrigerant vapor, and a temperature sensor for detecting a cooling water inlet / outlet temperature of a condenser, and a condenser. The temperature sensors that detect the temperature of the refrigerant condensed in the condenser, and the signals from these temperature sensors are input to calculate the logarithmic average temperature difference between the condensers, and the contamination of the cooling water system is calculated based on this logarithmic average temperature difference and the refrigeration load. An absorption refrigerating machine, comprising: a control device that calculates and determines the degree and outputs an opening signal for changing the set value of the maximum valve opening of the fuel control valve to the fuel control valve according to the degree of contamination of the cooling water system. . 4. An absorption refrigerating machine equipped with a generator for heating an absorbing liquid sent from an absorber to generate a refrigerant vapor, wherein a temperature sensor for detecting a cooling water inlet / outlet temperature of a condenser, and a condenser. The temperature sensors that detect the temperature of the refrigerant condensed in the condenser, and the signals from these temperature sensors are input to calculate the logarithmic average temperature difference between the condensers, and the contamination of the cooling water system is calculated based on this logarithmic average temperature difference and the refrigeration load. And a controller for outputting an opening signal to the fuel control valve that reduces the current valve opening by a predetermined ratio when the degree of contamination of the cooling water system is greater than or equal to a predetermined value. A characteristic absorption refrigerator.