JPH07269978A - Double effect absorption refrigerator - Google Patents

Abstract

PURPOSE:To provide an absorption refrigerator in which a high thermal efficiency can be maintained as a double effect absorption refrigerator and control characteristics at the time of partial load operation can be improved and absorption liquid circulating pump power can be reduced. CONSTITUTION:The double effect absorption refrigerator comprises absorption liquid tube so split and piped separately to a high temperature regenerator 1 and a low temperature regenerator 2 via a low temperature heat exchanger 6 with absorption liquid of an absorber 5 for absorbing the refrigerator, a first absorption liquid pump P2 provided between the absorber 5 and a low temperature heat exchanger 6, a second absorption liquid pump P3 provided between a branch 11a and the regenerator 1, and a controller 9 for controlling number of revolutions of the pump P3 based on an output signal of a liquid level sensor 8 installed at the regenerator 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a double-effect absorption refrigerating machine used for heating and cooling operation, and more particularly, to improve control characteristics during partial load operation and reduce power of absorption liquid circulating pump. Is.

[0002]

2. Description of the Related Art A high temperature regenerator 1, a low temperature regenerator 2, a condenser 3, an evaporator 4 and an absorber 5 as conventionally illustrated in FIG.
-Double-effect absorption refrigeration in which a low-temperature heat exchanger 6 and a high-temperature heat exchanger 7 are connected by piping to circulate a refrigerant (for example, water) and an absorbing liquid (for example, an aqueous solution of lithium bromide) to form a refrigeration cycle. The machine is known. In the figure, P1 and P2 are pumps for circulating the refrigerant and the absorbing liquid, respectively.
Reference numeral 8 is a liquid level sensor for detecting the liquid level of the absorbing liquid in the high temperature regenerator 1, and 9 is a controller for receiving the signal output from the liquid level sensor and controlling the opening of the flow control valve V1. .

The high temperature regenerator 1 absorbs the absorbing liquid which has become a rare liquid by absorbing the refrigerant in the absorber 5 by one absorbing liquid pump P2.
In the double-effect absorption chiller having the above-described structure, which circulates the water to the low temperature regenerator 2 at the same time, the water cooled through the heat transfer pipe 21a by the heat of vaporization of the refrigerant in the evaporator 4 flows inside the cold water pipe 21. Fluctuations in the load 10 that is circulated and supplied,
When the temperature of the cooling water flowing through the cooling water pipe 22 and flowing into the absorber 5 fluctuates, the pressure fluctuation in the low temperature regenerator 2 is only about several hundred Pa at most, but the pressure fluctuation in the high temperature regenerator 1 does not change. Since it may reach several tens of kPa, if the rotation speed of the absorbing liquid pump P2 is controlled according to the operating state of the high temperature regenerator 1, the circulation amount of the absorbing liquid to the low temperature regenerator 2 will fluctuate greatly, and There is a problem that the control characteristics of the refrigerator are deteriorated. Further, the head of the absorbent pump P2 is selected in consideration of the internal pressure of the high temperature regenerator 1 and the pressure loss in each of the low temperature heat exchanger 6 and the high temperature heat exchanger 7,
There is also a problem that this required power becomes large and it is not economical.

Further, as shown in FIG. 3 of Japanese Patent Laid-Open No. 60-2862, the absorption liquid circulates between the absorber 5 and the high temperature regenerator 1 by two absorption liquid pumps P4 and P5. An absorption refrigerator having a high-temperature absorption liquid circuit 23 and a low-temperature absorption liquid circuit 24 in which the absorption liquid circulates between the absorber 5 and the low-temperature regenerator 2 is disclosed. In the refrigerator, the absorption liquid of the low temperature absorption liquid circuit 24 exchanges heat only with the low temperature heat exchanger 6, and the absorption liquid of the high temperature absorption liquid circuit 23 exchanges heat with only the high temperature heat exchanger 7, as illustrated in FIG. Like a double-effect absorption chiller, from absorber 5 to high temperature regenerator 1
There is a problem that the total thermal efficiency (COP) is low because the absorption liquid supplied to the heat exchanger is not configured to exchange heat with both the low temperature heat exchanger 6 and the high temperature heat exchanger 7.

[0005]

Therefore, the high thermal efficiency of the dual-effect absorption refrigerator can be maintained, the control characteristics during partial load operation can be improved, and the absorption liquid circulation pump power can be reduced. The development of refrigerators has been an issue.

[0006]

The present invention has been made in order to solve the above-mentioned problems of the prior art, and includes an absorber, an evaporator, a condenser, a high temperature regenerator, a low temperature regenerator, and a low temperature heat exchanger. In a dual-effect absorption refrigerator that connects a high-temperature heat exchanger, etc., to form a circulation cycle of refrigerant and absorbing liquid, the absorbing liquid that has absorbed the refrigerant inside the absorber passes through the low-temperature heat exchanger and is then regenerated at high temperature. The absorption liquid pipe is branched so as to be able to flow into the reactor and the low temperature regenerator separately, and a first absorption liquid circulation pump is provided between the absorber and the low temperature heat exchanger of the absorption liquid pipe, A double-effect absorption refrigerating machine having a first structure in which a second absorption liquid circulation pump is provided between a branch portion and the high temperature regenerator;

The absorption liquid, which has absorbed the refrigerant inside the absorber, passes through the low temperature heat exchanger and is then split into the high temperature regenerator and the low temperature regenerator so that the absorption liquid pipe is branched and the absorption liquid pipe is A first absorption liquid circulation pump is provided between the absorber and the low temperature heat exchanger, a second absorption liquid circulation pump is provided between a branch portion and the high temperature regenerator, and the high temperature A double-effect absorption refrigerator having a second configuration, which is provided with a controller for controlling the rotation speed of the second absorbent circulation pump based on a signal detected and output by the state detection sensor of the regenerator. However, the problems of the above-mentioned conventional techniques are solved.

[0008]

When the pressure fluctuation in the high temperature regenerator reaches several tens of kPa, the absorbing liquid that has absorbed the refrigerant inside the absorber passes through the low temperature heat exchanger and then flows into the high temperature regenerator and the low temperature regenerator separately. This can be easily dealt with by controlling the number of revolutions of the second absorption liquid circulation pump provided between the high temperature regenerator and the branch portion of the absorption liquid pipe which is branched as possible.

Further, the first absorption liquid circulation pump provided between the absorber of the absorption liquid pipe and the low temperature heat exchanger circulates and supplies the absorption liquid from the absorber to the low temperature regenerator. The influence of pressure fluctuation of the high temperature regenerator on the amount of liquid fed to the low temperature regenerator is extremely small, and therefore the control characteristics of the absorption refrigerator are improved. Further, the head of the first absorption liquid circulation pump can be selected according to the low temperature regenerator having a low pressure, so that the pump power can be reduced.

[0010]

An embodiment of the present invention will be described in detail below with reference to FIG. In addition, in order to facilitate understanding, FIG.
In FIG. 2 also, parts having the same functions as those described in FIGS. 2 and 3 are given the same reference numerals.

In the absorption refrigerating machine of the present invention, the circulation supply of the absorption liquid from the absorber 5 to the high temperature regenerator 1 is directly branched from the branch portion 11a of the absorption liquid pipe 11 as shown in FIG. This is performed by the driving force of the absorbent pump P3 provided in the middle of the absorbent pipe 12. The number of revolutions of the absorbent pump P3 is controlled by the controller 9 based on the liquid level data of the absorbent detected by the sensor for detecting the state of the high temperature regenerator 1, for example, the liquid level sensor 8 and output. To be done.

Further, the low temperature heat exchanger 6 includes an absorbing liquid pipe 11 from the absorber 5 toward the high temperature regenerator 1 or the low temperature regenerator 2.
The absorption liquid flowing through the inside of the reactor is heated by the high-temperature regenerator 1 or the low-temperature regenerator 2 toward the absorber 5, and the absorption liquid pipe 16
Is a heat exchanger for exchanging heat with the absorbing liquid flowing inside, and the high temperature heat exchanger 7 is the absorbing liquid flowing inside the absorbing liquid pipe 12 toward the high temperature regenerator 1 by the absorbing liquid pump P3. And the absorption liquid heated in the high temperature regenerator 1 and flowing inside the absorption liquid pipe 14 toward the confluence 15a with the absorption liquid pipe 15 are heat exchangers.

That is, in the absorption refrigerating machine of the present invention having the above-mentioned structure, the absorption liquid of the absorber 5, that is, the absorption liquid which has absorbed the refrigerant evaporated from the evaporator 4 and has the increased refrigerant concentration is absorbed by the absorber. 5 is discharged to the absorption liquid pipe 11 by the driving force of the absorption liquid pump P2, is heated by the high temperature regenerator 1 or the low temperature regenerator 2, and is a high temperature absorption liquid flowing through the absorption liquid pipe 16 toward the absorber 5. The low temperature heat exchanger 6 heats by exchanging heat. Then, the branch portion 11a of the absorption liquid pipe 11
The absorption liquid flowing into the absorption liquid pipes 12 and 13 separately from one another and flowing through one of the absorption liquid pipes 12 is subjected to high temperature heat exchange with the high temperature absorption liquid flowing in the absorption liquid pipe 14 after being heated by the high temperature regenerator 1. After the heat is exchanged in the vessel 7 to be further heated, it flows into the high temperature regenerator 1, and the absorbing liquid flowing through the other absorbing liquid pipe 13 directly flows into the low temperature regenerator 2.

The absorption liquid flowing into the high temperature regenerator 1 from the absorption liquid pipe 12 is heated by the heating means 1a such as a burner, and the refrigerant absorbed in the absorption liquid is evaporated and separated to obtain the concentration of the absorption liquid (lithium bromide). The absorption liquid pipe 14
Flowing out into the high temperature heat exchanger 7 and exchanging heat with the absorbing liquid having a relatively low temperature flowing in the absorbing liquid pipe 12 to heat the absorbing liquid to lower its own temperature. Then, the low temperature regenerator 2 flows into the low temperature regenerator 2 through the absorption liquid pipe 13 and is heated,
Of the absorbing liquid discharged into the low temperature heat exchanger 6 and heats the absorbing liquid which flows into the low temperature heat exchanger 6 and heats the absorbing liquid. Further lower and return to the absorber 5.

On the other hand, the refrigerant vapor which has been heated by the heating means 1a in the high temperature regenerator 1 and evaporated and separated from the absorbing liquid flows into the low temperature regenerator 2 through the refrigerant vapor pipe 17, and from the absorbing liquid pipe 13 there. It heats by exchanging heat with the flowing-in absorption liquid, and is cooled and condensed. From the low temperature regenerator 2 to the condenser 3, the refrigerant condensed in the low temperature regenerator 2 flows in via a refrigerant pipe 19 having a steam trap 19a in the middle, and a refrigerant vapor pipe 18 or a refrigerant having a steam trap 19a in the middle. Refrigerant vapor flows in through the pipe 19, where it is heat-exchanged with the cooling water supplied through the inside of the cooling water pipe 22 and condensed.

The refrigerant liquid condensed in the condenser 3 flows into the evaporator 4 maintained at a low pressure through the refrigerant liquid pipe 20 having a U-shaped portion 20a on the way, and cool water is supplied from the sprayer 4a provided at the upper portion. Water is sprayed on the heat transfer pipe 21a of the pipe 21 by the driving force of the refrigerant pump P1 and exchanges heat with the water flowing in the heat transfer pipe 21a to cool it. The water cooled by the heat of vaporization of the refrigerant through the tube wall of the heat transfer tube 21a is circulated and supplied to the load 10 through the cold water tube 21 and is used for the cooling operation.

Then, based on the liquid level data of the absorbing liquid detected and output by the liquid level sensor 8 by the controller 9, when the liquid level becomes higher than a predetermined level by, for example, 50 mm, the absorbing liquid pump P3. The circulating supply amount of the absorbing liquid to the high temperature regenerator 1 is reduced by decreasing the voltage applied to the high temperature regenerator 1, and conversely, when the liquid level becomes lower than a predetermined level, for example, 50 mm, the absorbing liquid pump P3 is By increasing the applied voltage and increasing the rotation speed, the circulating supply amount of the absorbing liquid to the high temperature regenerator 1 is increased, and the control for suppressing the fluctuation of the liquid surface level within a certain range is performed.

In the absorption refrigerator having the controller 9 having the above function, when the load 10 decreases and the temperature rise width of the water circulating through the cold water pipe 21 and returning to the evaporator 4 becomes smaller than a predetermined value. , The amount of heat that can be radiated to the refrigerant via the heat transfer tube 21a decreases → the amount of refrigerant evaporation in the evaporator 4 decreases → the pressure and temperature in the absorber 5 decrease → the heat transfer tube 22 of the cooling water pipe 22
The temperature rise width of the cooling water discharged from the absorber 5 through a is reduced → The rise width of the pressure and temperature inside the condenser 3 into which this cooling water flows is reduced → The pressure and temperature inside the low temperature regenerator 2 are reduced → The pressure and temperature in the high temperature regenerator 1 decrease → The liquid delivery pressure by the absorption liquid pump P3 decreases, which increases the amount of liquid delivery to the high temperature regenerator 1 by the absorption liquid pump P3 and absorbs in the high temperature regenerator 1. Although the liquid level of the liquid rises, the controller 9 drives the absorbing liquid pump P3 at a low speed based on the liquid level data of the absorbing liquid detected and output by the liquid level sensor 8, so that the high temperature regeneration is performed. Since the liquid level of the absorbing liquid in the container 1 is within a predetermined range, and the supplying of the absorbing liquid to the low temperature regenerator 2 is performed by the absorbing liquid pump P2, it does not fluctuate significantly. The control characteristics are improved.

Since the present invention is not limited to the above embodiment, various modifications can be made according to the spirit of the claims.

For example, the absorption liquid pump P3 by the controller 9
In order to control the number of rotations of the high temperature regenerator 1, a pressure sensor for detecting the vapor pressure of the high temperature regenerator 1 is provided in place of the liquid level sensor 8 or the vapor pressure of the high temperature regenerator 1 is indirectly detected. Is provided in the refrigerant vapor pipe 17, and based on the pressure data detected and output by this pressure sensor,
During partial load operation in which the vapor pressure becomes lower than a predetermined pressure, the rotation speed of the absorption liquid pump P3 is reduced to reduce the supply amount of the absorption liquid to the high temperature regenerator 1, and when it becomes higher than the predetermined pressure, the rotation of the absorption liquid pump P3. It is also possible to increase the number and control so as to increase the circulating supply amount of the absorbing liquid to the high temperature regenerator 1.

Further, a temperature sensor for detecting the temperature of the absorbing liquid discharged from the high temperature regenerator 1 to the absorbing liquid pipe 14 or the absorbing liquid discharged to the absorbing liquid pipe 14 is provided, and this temperature sensor detects and outputs. On the basis of the temperature data, during partial load operation in which the temperature becomes lower than the predetermined temperature, the rotation speed of the absorption liquid pump P3 is reduced to reduce the circulating supply amount of the absorption liquid to the high temperature regenerator 1, and when the temperature becomes higher than the predetermined temperature. It is also possible to increase the rotation speed of the absorption liquid pump P3 to increase the circulation supply amount of the absorption liquid to the high temperature regenerator 1.

Further, instead of the temperature of the absorbing liquid, the temperature of the refrigerant vapor flowing through the refrigerant vapor pipe 17 having a correlation with this temperature is detected to control the rotation of the absorbing liquid pump P3. It is also possible to do so.

Further, a plurality of required state detection sensors are provided so as to detect a plurality of physical quantities such as the liquid level, pressure and temperature, which indicate the operating state of the high temperature regenerator 1, and the data detected by these sensors are provided. When any one of or a plurality of data of the above-mentioned values simultaneously deviates from a predetermined value and a partial load operation is performed, the rotational speed of the absorption liquid pump P3 is reduced to restrict the circulation supply of the absorption liquid to the high temperature regenerator 1. You can also do it.

The number of revolutions of the absorbing liquid pump P3 can be frequency controlled instead of the applied voltage control.

Further, the refrigerant vapor pipe 17 is branched so that the refrigerant vapor generated by the heating of the high temperature regenerator 1 can directly flow into the low pressure cylinder of the evaporator 4 and the absorber 5, and the heat held by the refrigerant vapor causes the heat transfer pipe 21a. It is also possible to heat the water flowing inside and circulate and supply this hot water to the load 10 to enable heating or hot water supply operation.

[0026]

As described above, according to the double-effect absorption refrigerator according to the present invention, even if the pressure fluctuation in the high temperature regenerator reaches several tens of kPa, the absorption liquid that has absorbed the refrigerant inside the absorber is absorbed. The second absorption liquid circulation provided between the high temperature regenerator and the branch part of the absorption liquid pipe in which the high temperature regenerator and the low temperature regenerator are separated and passed through the low temperature heat exchanger so as to be able to flow in separately. It is possible to easily respond by controlling the rotation speed of the pump,

Further, the absorption liquid is circulated and supplied from the absorber to the low temperature regenerator by the first absorption liquid circulation pump provided between the absorber of the absorption liquid pipe and the low temperature heat exchanger. The influence of the pressure fluctuation of the high temperature regenerator on the amount of liquid fed to the low temperature regenerator is extremely small, and the control characteristics of the absorption refrigerator are improved. Further, since the pump head of the first absorption liquid circulation pump can be selected according to the low temperature regenerator having a low pressure, the pump power can be reduced and other remarkable effects can be obtained.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing an example.

FIG. 2 is an explanatory diagram showing a conventional example.

FIG. 3 is an explanatory diagram showing another conventional example.

[Explanation of symbols]

 1 High temperature regenerator 1a Heating means 2 Low temperature regenerator 3 Condenser 4 Evaporator 5 Absorber 6 Low temperature heat exchanger 7 High temperature heat exchanger 8 Liquid level sensor 9 Controller 10 Load 11 ・ 12 ・ 13 ・ 14 ・ 15 ・16 Absorbing liquid pipe 11a Branching part 15a Merging part 17 ・ 18 Refrigerant vapor pipe 19 Refrigerant pipe 19a Steam trap 20 Refrigerant liquid pipe 20a U-shaped portion 21 Cooling water pipe 21a Heat transfer pipe 22 Cooling water pipe P1 Refrigerant circulation pump P2 ・ P3 ・ P4 ・P4 Absorption liquid circulation pump V1 Flow control valve

Claims (2)

[Claims] 1. An absorber, an evaporator, a condenser, a high temperature regenerator,
In a dual-effect absorption chiller in which a low-temperature regenerator, low-temperature heat exchanger, high-temperature heat exchanger, etc. are connected by piping to form a circulation cycle of refrigerant and absorbing liquid, the absorbing liquid that has absorbed the refrigerant inside the absorber has a low temperature. After passing through the heat exchanger, the absorption liquid pipe is branched so as to be separately flown into the high temperature regenerator and the low temperature regenerator. 1. A double-effect absorption refrigerating machine, wherein the first absorption liquid circulation pump is provided, and the second absorption liquid circulation pump is provided between the branch portion and the high temperature regenerator. 2. An absorber, an evaporator, a condenser, a high temperature regenerator,
In a dual-effect absorption chiller in which a low-temperature regenerator, low-temperature heat exchanger, high-temperature heat exchanger, etc. are connected by piping to form a circulation cycle of refrigerant and absorbing liquid, the absorbing liquid that has absorbed the refrigerant inside the absorber has a low temperature. After passing through the heat exchanger, the absorption liquid pipe is branched so as to separately flow into the high temperature regenerator and the low temperature regenerator, and the absorption liquid pipe is connected between the absorber and the low temperature heat exchanger. 1 absorption liquid circulation pump is provided, a 2nd absorption liquid circulation pump is provided between the branch part and the said high temperature regenerator, and based on the signal which the state detection sensor of the said high temperature regenerator detects and outputs. A double-effect absorption refrigerator having a controller for controlling the number of revolutions of the second absorbent circulation pump.