JP2009085509A - Method of preventing crystallization of absorbent of high concentration in low-temperature heat exchanger in absorption type refrigerating machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent the crystallization of lithium bromide in a low-temperature heat exchanger through which, in particular, an absorbent of a high concentration passes in an absorption type refrigerating machine. <P>SOLUTION: In a double effect absorption type refrigerating machine comprising an absorber 1, a high-temperature regenerator 3, a low-temperature regenerator 5, a condenser 9, an evaporator 10 and the like, the absorbent of a high concentration produced in the low-temperature regenerator 5 is passed through the low-temperature heat exchanger 7 through a pipe conduit L3 by a concentrated liquid pump 6 and introduced to the absorber 1. A temperature sensor Ts is disposed at the outlet side of the low-temperature heat exchanger 7 to measure a temperature of the absorbent of the high concentration at the outlet side of the low-temperature heat exchanger 7, and the concentration or/and heat exchange amount of the absorbent of the high concentration are controlled on the basis of the measured temperature and a crystallization temperature of the absorbent of the high concentration. Thus the crystallization of lithium bromide in the low-temperature heat exchanger 7 can be prevented. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an absorption refrigerator, and more particularly to a method for preventing crystallization of a high-concentration absorption liquid in a low-temperature heat exchanger.

  2. Description of the Related Art Conventionally, for example, a dual effect absorption refrigerator having a high temperature regenerator and a low temperature regenerator using a lithium bromide solution as an absorption liquid and water as a refrigerant is well known. In this double-effect absorption refrigerator, for example, as shown in FIG. 3, the absorption liquid that has absorbed refrigerant refrigerant in the absorber 1 and has a low concentration is returned to the high-temperature regenerator 3 by the dilute liquid pump 2. The refrigerant vapor is separated by heating with the burner 4 in the regenerator 3. The absorbing liquid having a medium concentration as a result of separation of the refrigerant vapor is introduced into the low temperature regenerator 5 through the pipe L1, and the refrigerant vapor separated in the high temperature regenerator 3 is cooled through the pipe L2. The refrigerant vapor is re-separated by passing through the regenerator 5 and heating the medium concentration absorbent in the low-temperature regenerator 5. The absorption liquid having a high concentration as a result of re-separation of the refrigerant vapor passes through the low-temperature heat exchanger 7 through the conduit L3 by the concentrated liquid pump 6 and is introduced into the absorber 1. In the pipe line L3, a bypass pipe line 8 connecting the upstream side of the concentrated liquid pump 6 and the downstream side of the low-temperature heat exchanger 7 is provided.

On the other hand, in the low-temperature regenerator 5, the refrigerant vapor re-separated from the medium concentration absorbing liquid is introduced into the condenser 9 and condensed by the cooling water passing through the condenser 9 through the pipe L 4. The refrigerant liquid is re-separated by the low-temperature regenerator 5 and then merged with the refrigerant liquid introduced into the bottom of the condenser 9 as the refrigerant liquid. The merged refrigerant liquid is introduced into the evaporator 10 via the pipe line L5, and is sprayed from the spraying device 12 on the evaporator 10 to the heat transfer pipe 13 by the refrigerant pump 11, and the cold temperature passing through the heat transfer pipe 13 is reached. It becomes refrigerant vapor by heat exchange with water. And this refrigerant | coolant vapor | steam is introduce | transduced into the said absorber 1, and the high concentration absorption liquid introduce | transduced from the said low-temperature regenerator 5 in this absorber 1 is spread | dispersed from the upper spreading | diffusion apparatus 14, and a refrigerant | coolant vapor | steam is absorbed thereby. The absorption liquid having a low concentration is returned to the high-temperature regenerator 3 through the pipe L6 by the diluted liquid pump 2. Such double-effect absorption refrigerators are disclosed in, for example, Patent Document 1 and Patent Document 2.
JP-A-2005-282968 JP 2005-300126 A

  In the absorption refrigerator as described above, lithium bromide used as an absorbent has the property of crystallizing depending on the conditions of concentration and temperature. For example, in a high-temperature regenerator, the concentration of the absorbent becomes too high due to overheating of the burner, resulting in crystallization of lithium bromide, or a high-concentration absorbent that is introduced from the low-temperature regenerator into the absorber via a conduit. However, crystallization may occur in a low-temperature heat exchanger that passes in the middle of the pipeline. In this way, when lithium bromide in the absorbing solution is crystallized, it precipitates in the absorption refrigerator and the absorbing solution is circulated, resulting in a decrease in efficiency and a failure or breakage.

  The present invention has been made to eliminate the disadvantages of such conventional absorption refrigerators, and in particular, to prevent crystallization of lithium bromide in a low-temperature heat exchanger through which a high concentration absorption liquid passes. .

As means for achieving the above-mentioned object, claim 1 of the present invention uses lithium bromide as an absorbent and water as a refrigerant, and the absorption liquid that has become a low concentration by absorbing refrigerant vapor with an absorber has a high temperature. The refrigerant vapor is separated from the low-concentration absorbent by returning to the regenerator and heated by this high-temperature regenerator, and the medium-concentrated absorbent is introduced into the low-temperature regenerator and separated from the low-concentration absorbent. The refrigerant vapor passed through the low-temperature regenerator through the pipe line, and then the refrigerant of the refrigerant vapor is re-separated by heating the medium-concentration absorbing liquid, and then introduced into the bottom of the condenser as a refrigerant liquid. Absorbed liquid, which has become a high concentration due to re-separation of the refrigerant vapor in the regenerator, passes through the low-temperature heat exchanger by the concentrated liquid pump, and the low-concentrated absorbent and heat return from the absorber to the high-temperature regenerator with this low-temperature heat exchanger. This concentrated pump is introduced into the absorber after replacement A bypass pipe connecting the upstream side and the downstream side of the low-temperature heat exchanger is provided, and the refrigerant vapor re-separated from the medium-concentration absorbing liquid is introduced into the condenser, and inside the condenser via the pipe. The refrigerant is condensed by the cooling water passing through the refrigerant and becomes a refrigerant liquid. The refrigerant liquid merges with the refrigerant liquid at the bottom of the condenser and is introduced into the evaporator, and from the evaporator spraying device to the heat transfer tube via the refrigerant pump. The refrigerant vapor is formed by spraying and exchanging heat with cold / hot water passing through the heat transfer pipe, and this refrigerant vapor is introduced into the absorber, and the high-concentration absorption liquid introduced from the low-temperature regenerator is introduced into the absorber. In the absorption refrigeration machine configured to absorb the refrigerant vapor sprayed from the spraying device of the absorber and return to the high-temperature regenerator through the rare liquid pump,
A temperature sensor is provided on the outlet side of the low-temperature heat exchanger, the temperature of the high-concentration absorbing liquid on the outlet side of the low-temperature heat exchanger is measured, and based on the measured temperature and the crystallization temperature of the high-concentration absorbing liquid The gist is a method for preventing crystallization of a high-concentration absorbent liquid in a low-temperature heat exchanger in an absorption refrigerator in which the concentration or / and heat exchange amount of the high-concentration absorbent liquid is controlled.

  Claim 2 of the present invention is the method for preventing crystallization of a high concentration absorbent in a low-temperature heat exchanger in the absorption refrigerator according to claim 1, wherein the measured temperature of the high concentration absorbent and the crystal of the high concentration absorbent are used. The inverter motor frequency of the concentrated liquid pump is increased before the high-concentration absorbing liquid is crystallized based on the crystallization temperature.

  Claim 3 of the present invention is the method for preventing crystallization of a high-concentration absorbent in a low-temperature heat exchanger in the absorption refrigerator according to claim 1, wherein the measurement temperature of the high-concentration absorbent and the crystal of the high-concentration absorbent are used. The inverter motor frequency of the dilute liquid pump is increased before the high-concentration absorbing liquid crystallizes based on the crystallization temperature.

  According to the first aspect of the invention, a high temperature regenerator, a low temperature regenerator, a condenser, an evaporator, and an absorber are provided, lithium bromide is used as an absorbent, water is used as a refrigerant, and refrigerant vapor is generated in the low temperature regenerator. Absorbed liquid that has been re-separated to a high concentration passes through a low-temperature heat exchanger via a conduit by a concentrated liquid pump, and returns to the high-temperature regenerator from the absorber with this low-temperature heat exchanger. In a dual-effect absorption refrigerator that is exchanged and introduced into the absorber, a temperature sensor is provided on the outlet side of the low-temperature heat exchanger, and the temperature of the high-concentration absorbent on the outlet side of the low-temperature heat exchanger is measured. By controlling the concentration or / and heat exchange amount of the high concentration absorbent based on the measured temperature and the crystallization temperature when the lithium bromide of the high concentration absorbent is crystallized, Crystallization of the high concentration absorbent can be prevented.

  According to the invention of claim 2 above, based on the measurement temperature of the high concentration absorbent on the outlet side of the low temperature heat exchanger and the crystallization temperature when the lithium bromide of the high concentration absorbent crystallizes, By increasing the inverter motor frequency of the concentrate pump before the high-concentration absorbing liquid crystallizes, the amount of the high-concentration absorbing liquid flowing to the low-temperature heat exchanger increases, and the low-temperature heat exchanger increases by this increased liquid amount. Therefore, the crystallization of the high-concentration absorbing liquid can be prevented.

  According to the third aspect of the invention, based on the measurement temperature of the high concentration absorbent on the outlet side of the low temperature heat exchanger and the crystallization temperature when the lithium bromide of the high concentration absorbent is crystallized, By increasing the inverter motor frequency of the dilute liquid pump before the high-concentration absorbent crystallizes, the amount of low-concentration absorbent supplied from the absorber to the high-temperature regenerator increases, and from the high-temperature regenerator to the low-temperature regenerator. As the circulation amount of the medium concentration absorbing solution supplied increases and the concentration decreases, the concentration of the high concentration absorbing solution passing through the low temperature heat exchanger also decreases and the crystallization of lithium bromide Can be prevented.

  Next, embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a schematic configuration diagram for explaining an embodiment of a high-concentration absorption liquid crystallization preventing method in a low-temperature heat exchanger in an absorption refrigerator according to the present invention. In FIG. 1, the same or substantially the same members as those of the conventional example are denoted by the same reference numerals as described above. In the figure, 1 is an absorber, 3 is a high-temperature regenerator, 5 is a low-temperature regenerator, 9 is a condenser, 10 is an evaporator, and lithium double bromide is used as an absorbent and water is used as a refrigerant. Type refrigerator. In this absorption refrigerator, the low-concentration absorbing liquid that has absorbed the refrigerant vapor in the absorber 1 is returned to the high-temperature regenerator 3 by the dilute pump 2, and the low-temperature heat exchanger 7 and the high-temperature heat are in the middle of the pipe L6. It passes through the exchanger 15.

  In the high-temperature regenerator 3, the low concentration absorbent returned from the absorber 1 is heated by the burner 4 to separate the refrigerant vapor. The refrigerant vapor separated by the high-temperature regenerator 3 passes through the low-temperature regenerator 5 through the pipe L2 and becomes a refrigerant liquid through the refrigerant drain heat recovery unit 16, and is introduced into the bottom of the condenser 9. . Reference numeral 17 denotes a flow rate varying means provided on the downstream side of the refrigerant drain heat recovery unit 16 in order to control the amount of the refrigerant liquid introduced into the condenser 9, and has a branch passage and is also an electromagnetic valve or a flow rate adjustment valve. The control valve 18 is provided.

  In the low-temperature regenerator 5, the medium-concentration absorbing liquid generated in the high-temperature regenerator 3 is introduced through the high-temperature heat exchanger 15 through the pipe L 1 and passes through the low-temperature regenerator 5. The refrigerant vapor is re-separated by being heated by the vapor. The refrigerant vapor re-separated by the low-temperature regenerator 5 is introduced into the condenser 9, cooled and condensed by the cooling water passing through the condenser 9 through the pipe L 4, and becomes a refrigerant liquid to form the condenser 9. Accumulate at the bottom.

  The absorption liquid having a high concentration as a result of re-separation of the refrigerant vapor in the low-temperature regenerator 5 is introduced into the absorber 1 after passing through the low-temperature heat exchanger 7 via the conduit L3 by the concentrated liquid pump 6. Incidentally, a bypass line 8 connecting the upstream side of the concentrated liquid pump 6 and the downstream side of the low-temperature heat exchanger 7 is provided in the line L3. The bypass pipe 8 prevents cavitation of the concentrated liquid pump 6 and prevents crystallization of lithium bromide in the concentrated liquid pump 6.

  In the present invention, when the high-concentration absorbent produced by the low-temperature regenerator 5 by the concentrated liquid pump 6 passes through the low-temperature heat exchanger 7 and is introduced into the absorber 1, the high-concentration liquid is produced by the low-temperature heat exchanger 7. Control is performed so that crystallization of the absorbing solution does not occur. The outline of this control method will be described. A temperature sensor Ts is provided on the outlet side of the low-temperature heat exchanger 7, the temperature of the high-concentration absorbing liquid on the outlet side of the low-temperature heat exchanger 7 is measured, and the measured temperature and the high temperature are measured. Based on the crystallization temperature of the concentration absorbing solution, the concentration or / and heat exchange amount of the high concentration absorbing solution are controlled.

  When controlling the concentration of the high-concentration absorbing liquid, the inverter motor frequency of the concentrated liquid pump 6 is set at a stage before the measurement temperature of the high-concentration absorbing liquid on the outlet side of the low-temperature heat exchanger 7 reaches the crystallization temperature. Increase. Thereby, while increasing the liquid quantity of the high concentration absorption liquid which passes the low temperature heat exchanger 7, and shortening the passage time of the said high concentration absorption liquid in the said low temperature heat exchanger 7, a high concentration absorption liquid becomes By suppressing the temperature from decreasing to the crystallization temperature, crystallization of lithium bromide can be prevented.

  FIG. 2 shows an example of inverter motor frequency control of the concentrated liquid pump 6 in accordance with the change in crystal margin. Here, the crystal margin (° C.) = (Temperature of the high-concentration absorbing liquid at the outlet of the low-temperature heat exchanger) − (crystal temperature). The crystal temperature can be calculated from the concentration of the high-concentration absorbent, and the crystal temperature is calculated, and the circulation amount of the high-concentration absorbent is controlled by the difference between the low-temperature heat exchanger outlet temperature and the crystal temperature. For example, when (crystal margin) ≦ (crystal margin setting value) + (crystal avoidance temperature range), the operation is continued by increasing the inverter motor frequency calculation value of the previous concentrated liquid pump by 5 Hz. When (crystal margin) ≧ (crystal margin setting value) + (crystal avoidance temperature range) + 1 ° C., the inverter motor frequency of the concentrated liquid pump is set to a normal calculation value at that time. The crystal margin setting value has a setting range of 2.0 to 10.0 ° C, and the crystal avoidance temperature range has a setting range of 1.0 to 5.0 ° C.

  Conventionally, even if the crystal margin is calculated in the same manner, as a method of avoiding crystallization, the combustion of the burner of the high-temperature regenerator is stopped. For this reason, it has had a great influence on the cold water outlet temperature.

  On the other hand, when the prevention of crystallization is controlled by controlling the heat exchange amount of the high-concentration absorbent in the low-temperature heat exchanger 7, the low-concentration absorbent returned from the absorber 1 to the high-temperature regenerator 3 by the dilute liquid pump 2 This is done by controlling the amount of liquid when passing through the low-temperature heat exchanger 7. For this reason, the inverter motor frequency of the dilute liquid pump 2 is controlled, and the heat exchange amount of the high concentration absorbent in the low temperature heat exchanger 7 is controlled by changing the circulation amount of the low concentration absorbent.

In the case of this method, based on the temperature of the high-concentration absorbing liquid on the outlet side of the low-temperature heat exchanger 7, the inverter motor frequency of the dilute liquid pump 2 is increased before the crystallization starts. This
The amount of the low concentration absorbent supplied from the absorber 1 to the high temperature regenerator 3 increases, and the medium concentration absorbent supplied from the high temperature regenerator 3 to the low temperature regenerator 5 also increases. 4 does not increase the amount of heating, so that the concentration of the medium concentration absorbing liquid decreases, the concentration of the high concentration absorbing liquid passing through the low temperature heat exchanger 7 from the low temperature regenerator 5 can be decreased, and crystallization can be performed. Can be prevented. It is also possible to prevent crystallization of lithium bromide by using this method in combination with the above method.

  In the condenser 9, the refrigerant vapor re-separated from the medium concentration absorbing liquid in the low temperature regenerator 5 is introduced and cooled by the cooling water passing through the condenser 9 through the pipe L4 to become a refrigerant liquid. The refrigerant liquid introduced into the bottom of the condenser 9 through the variable resistance means 17 joins and accumulates at the bottom.

  In the evaporator 10, the refrigerant liquid accumulated at the bottom of the condenser 9 is introduced through the pipe L <b> 5, and is sprayed from the spraying device 12 disposed in the upper part of the evaporator 10 by the refrigerant pump 11. Heat exchange with cold / hot water passing through the evaporator 10 is performed. As a result, the refrigerant liquid evaporates and cools the cold / hot water, and the cooled cold / hot water is introduced into the load to perform a cooling operation.

In the absorber 5, as described above, the high-concentration absorbing liquid from the low-temperature regenerator 5 passes through the low-temperature heat exchanger 7 through the conduit L <b> 3 by the concentrated liquid pump 6 and is then sprayed from the spraying device 14 of the absorber 1. The The high-concentration absorbing liquid sprayed from the spraying device 14 is cooled by exchanging heat with the cooling water passing through the absorber 1 through the pipe L4, and absorbs the refrigerant vapor introduced from the evaporator 10. The low-concentration absorbing liquid whose concentration is reduced by absorbing the refrigerant vapor passes through the low-temperature heat exchanger 7 and the high-temperature heat exchanger 8 via the pipe L6 by the dilute pump 2 as described above, and then the high-temperature regenerator. 3 is introduced.
In addition, in the pipe line L6, the pipe line L7 branched on the upstream side of the low-temperature heat exchanger 7 passes through the refrigerant drain heat recovery unit 16 and is connected to the downstream side of the low-temperature heat exchanger 7.

The dual-effect absorption refrigerator has been described as an embodiment of the present invention. However, the above-described embodiment is merely an aspect of the present invention, and can be arbitrarily modified within the scope of the present invention. And application is possible.
For example, the present invention can also be applied to a triple effect absorption refrigerator. Further, the present invention can be applied to an absorption refrigerator that does not include the refrigerant drain heat exchanger 16 or the flow rate varying means 17, and can prevent crystallization of the high concentration absorbent.

  The present invention can be applied to a double-effect absorption refrigerator, and is a low-temperature heat exchanger provided in the middle of a pipeline for introducing a high-concentration absorption liquid from a low-temperature regenerator to an absorber by a concentrated liquid pump. Crystallization of lithium bromide can be prevented by controlling the concentration of the high concentration absorbent and / or the amount of heat exchange.

It is a schematic block diagram for demonstrating embodiment of the high concentration absorption liquid crystallization prevention method in the low-temperature heat exchanger in the absorption refrigerator which concerns on this invention. Description of an embodiment of a method for preventing crystallization of a high-concentration absorbent liquid in a low-temperature heat exchanger in an absorption refrigerator according to the present invention, showing an example of inverter motor frequency control of a concentrated liquid pump accompanying a change in crystal margin FIG. It is a schematic block diagram which shows the conventional absorption refrigerator.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Absorber 2 Rare liquid pump 3 High temperature regenerator 4 Burner 5 Low temperature regenerator 6 Concentrated pump 7 Low temperature heat exchanger 8 Bypass line 9 Condenser 10 Evaporator 11 Refrigerant pump 12 Spraying device 13 Heat transfer tube 14 Spreading device 15 High Heat exchanger 16 Refrigerant drain heat recovery unit 17 Flow rate variable means 18 Control valve

Claims (3)

Lithium bromide is used as the absorbent and water is used as the refrigerant. Absorbed liquid that has absorbed the refrigerant vapor in the absorber and has a low concentration is returned to the high-temperature regenerator, and is heated in this high-temperature regenerator, so that the low-concentration absorbent The refrigerant vapor is separated from the refrigerant and introduced into the low-temperature regenerator, and the refrigerant vapor separated from the low-concentration absorbent passes through the low-temperature regenerator via a pipe. After the refrigerant vapor is re-separated by heating the medium concentration absorbent, it is introduced into the bottom of the condenser as a refrigerant liquid, and the refrigerant liquid is concentrated again after being separated again in the low temperature regenerator. After passing through the low-temperature heat exchanger by the liquid pump and exchanging heat with the low-concentration absorbing liquid returning from the absorber to the high-temperature regenerator with this low-temperature heat exchanger, it is introduced into the absorber, and the upstream side of this concentrated liquid pump and the low-temperature heat There is a bypass line connecting the downstream side of the exchanger. The refrigerant vapor re-separated from the intermediate concentration absorbing liquid is introduced into the condenser, and is condensed by the cooling water passing through the condenser through a conduit to become the refrigerant liquid. The refrigerant is combined with the refrigerant liquid at the bottom of the vessel and introduced into the evaporator. The refrigerant is sprayed from the evaporator spraying device to the heat transfer pipe via the refrigerant pump and exchanges heat with cold / hot water passing through the heat transfer pipe. The refrigerant vapor is introduced into the absorber, and the high-concentration absorbing liquid introduced from the low-temperature regenerator is sprayed from the absorber spraying device to absorb the refrigerant vapor to a low concentration. In the absorption refrigerator having a configuration in which the absorbed liquid is returned to the high-temperature regenerator through a rare liquid pump,
A temperature sensor is provided on the outlet side of the low-temperature heat exchanger, the temperature of the high-concentration absorbing liquid on the outlet side of the low-temperature heat exchanger is measured, and based on the measured temperature and the crystallization temperature of the high-concentration absorbing liquid A method for preventing crystallization of a high-concentration absorbent liquid in a low-temperature heat exchanger in an absorption refrigerator, wherein the concentration or / and heat exchange amount of the high-concentration absorbent liquid is controlled.   The inverter motor frequency of the concentrated liquid pump is increased before the high concentration absorbent is crystallized based on the measured temperature of the high concentration absorbent and the crystallization temperature of the high concentration absorbent. The high concentration absorption liquid crystallization prevention method in the low-temperature heat exchanger in the absorption refrigerator as described.   2. The inverter motor frequency of the dilute liquid pump is increased before the high-concentration absorption liquid is crystallized based on the measured temperature of the high-concentration absorption liquid and the crystallization temperature of the high-concentration absorption liquid. The high concentration absorption liquid crystallization prevention method in the low-temperature heat exchanger in the absorption refrigerator as described.

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