JP2016099094A - Absorption refrigerator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a two-stage absorption cycle absorption refrigerator that can operate continuously even if a solution flows into a high-pressure side cycle from a low-pressure side cycle.SOLUTION: An absorption refrigerator comprises: a low-pressure side cycle including an evaporator, a low-pressure absorber, and a low-pressure regenerator; and a high-pressure side cycle including a high-pressure absorber, a high-pressure regenerator, and a condenser. The absorption refrigerator has a structure in which refrigerant vapor generated from the low-pressure regenerator is absorbed in a solution of the high-pressure absorber, and performs control so that the liquid level of a solution stored in a bottom part of the low-pressure regenerator is kept at a predetermined value or higher.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an absorption refrigerator having a two-stage absorption cycle for supplying a heat source medium to two regenerators.

  The absorption refrigerator of the two-stage absorption cycle includes a low-pressure side cycle consisting of an evaporator, a low-pressure absorber and a low-pressure regenerator, and a high-pressure side cycle consisting of a high-pressure absorber, a high-pressure regenerator and a condenser, and low-pressure regeneration The refrigerant vapor obtained by heating and evaporating the solution with the heat source medium in the vessel is absorbed into the solution of the high pressure absorber, thereby connecting the low pressure side cycle and the high pressure side cycle. It is known that an absorption refrigerator having a two-stage absorption cycle can be driven by a heat source having a temperature lower than that of a single-effect absorption refrigerator.

  In JP 2004-211979 (Patent Document 1), as an absorption refrigerator of a two-stage absorption cycle, a solution circulating through a low-pressure absorber and a low-pressure regenerator serving as a low-pressure side cycle and a high-pressure side cycle are disclosed. A cycle flow diagram is described in which the solution circulating through the high-pressure absorber and the high-pressure regenerator circulates independently through the high-pressure side cycle and the low-pressure side cycle without mixing.

JP 2004-211979 A

  In the two-stage absorption cycle, the solution in the low-pressure side cycle circulating through the low-pressure absorber and the low-pressure regenerator and the solution in the high-pressure side cycle circulating through the high-pressure absorber and the high-pressure regenerator are circulated independently. . Therefore, when the refrigerant is water and the solution is a lithium bromide aqueous solution, the amount of lithium bromide does not change even if the solution concentration changes depending on the operating conditions. That is, the solution concentration of the low-pressure side cycle and the high-pressure side cycle is determined by the operating conditions, and the amount of refrigerant stored in the evaporator is adjusted and changed according to the solution concentration. Therefore, in the absorption refrigerator of the two-stage absorption cycle, the refrigerant amount and the solution amount are determined and sealed so that there is no problem even if the solution concentration changes depending on the operating conditions.

  On the other hand, in the low pressure regenerator and the high pressure absorber connecting the low pressure side cycle and the high pressure side cycle, the refrigerant vapor evaporated in the low pressure regenerator is absorbed by the solution in the high pressure absorber. Generally, a heat exchanger having a plurality of heat transfer tubes is accommodated inside the low-pressure regenerator and the high-pressure absorber, and the solution is sprayed from a spraying unit disposed on the top of the heat exchanger. Since the sprayed solution repeatedly flows down from the upper part of the heat exchanger to the upper part of the outer surface of the heat transfer tube and separates from the lower part of the outer surface of the heat transfer tube, fine droplets are generated. At this time, under the condition of increasing the refrigerating capacity, the amount of refrigerant vapor increases, so the flow velocity of refrigerant vapor increases, and fine droplets generated in the low pressure regenerator flow into the high pressure absorber along with the refrigerant vapor flow. It is possible to do.

  When the solution in the low-pressure side cycle flows into the high-pressure side cycle, the amount of lithium bromide decreases in the low-pressure side cycle, so the amount of solution decreases to maintain the concentration, and in the high-pressure side cycle, the amount of lithium bromide increases, so the concentration increases. Increased solution volume to maintain.

  For this reason, in the low-pressure side cycle, the amount of solution gradually decreases, and it is considered that the liquid level is lowered due to a lack of solution in the low-pressure regenerator or low-pressure absorber, and continuous operation cannot be performed.

  An object of the present invention is to obtain an absorption refrigerator having a two-stage absorption cycle capable of continuous operation even when a solution flows from the low pressure side cycle to the high pressure side cycle.

  The absorption refrigerator of the present invention includes a low-pressure side cycle including an evaporator, a low-pressure absorber and a low-pressure regenerator, and a high-pressure side cycle including a high-pressure absorber, a high-pressure regenerator and a condenser. The generated refrigerant vapor is absorbed by the solution in the high pressure absorber, and is controlled so that the liquid level of the solution stored at the bottom of the low pressure regenerator is maintained at a predetermined value or more.

  ADVANTAGE OF THE INVENTION According to this invention, even if a solution flows in into a high voltage | pressure side cycle from a low pressure side cycle, the absorption refrigerator of the two-stage absorption cycle which can be operated continuously can be obtained.

It is a schematic block diagram which shows the absorption refrigerator of this invention. It is a fragmentary sectional view which shows the Example which deform | transformed the part enclosed with the broken line of the ellipse of FIG. It is a fragmentary sectional view which shows another Example which deform | transformed the part enclosed with the broken line of the ellipse of FIG.

  Hereinafter, specific embodiments of the present invention will be described with reference to the drawings. Note that, in each drawing, the portions denoted by the same reference numerals indicate the same or corresponding portions.

  FIG. 1 is a cycle system diagram showing an absorption refrigerator according to a first embodiment of the present invention.

  First, the overall configuration of this embodiment will be described with reference to FIG. The absorption refrigerator includes a heat exchanger element of a low pressure side cycle including an evaporator 1 (E), a low pressure absorber 9 (LA), a low pressure regenerator 17 (LG), and a low pressure side solution heat exchanger 16, and a high pressure absorption. And a high-pressure side cycle heat exchanger element including a high-pressure side regenerator 33 (HG), a condenser 41 (C), and a high-pressure side solution heat exchanger 31. In addition, the absorption refrigerator includes a refrigerant pump 6, solution pumps 14, 22, 29, 38, and the like.

  In the evaporator 1, the refrigerant stored in the lower part of the evaporator 1 is guided to the distribution unit 2 through the refrigerant pipe 7 by the refrigerant pump 6 and is distributed outside the heat transfer tube of the heat exchanger 3. The dispersed refrigerant is heated by the cold water flowing in the heat transfer tube of the heat exchanger 3, and a part of the refrigerant becomes refrigerant vapor and is led to the low pressure absorber 9 through the eliminator 8. At this time, the cold water flowing through the heat transfer tubes of the heat exchanger 3 is cooled using the latent heat of evaporation when the refrigerant evaporates. Cold water pipes 4 and 5 are connected to the heat exchanger 3, and cold water for supplying cold heat to the load side is passed through.

  In the low pressure absorber 9, the solution concentrated in the low pressure regenerator 17 is sprayed from the spray unit 10 to the outside of the heat transfer tube of the heat exchanger 11. The sprayed solution absorbs the refrigerant vapor from the evaporator 1 and becomes thin in concentration. Thereafter, the solution is guided to the low-pressure regenerator 17 through the low-pressure side solution heat exchanger 16 by the solution pump 14 installed in the middle of the solution pipe 15. Cooling water is passed through the heat transfer tubes of the heat exchanger 11 in order to remove the absorbed heat generated when the solution absorbs the refrigerant vapor. Cooling water pipes 12 and 13 are connected to the heat exchanger 11.

  In the low-pressure regenerator 17, the solution having a low concentration in the low-pressure absorber 9 is sprayed from the spray unit 18 to the outside of the heat transfer tube of the heat exchanger 19. The sprayed solution is heated by a heat source medium flowing in the heat transfer tube of the heat exchanger 19 and separated into a concentrated solution and refrigerant vapor. The concentrated solution is guided to the low pressure absorber 9 through the low pressure side solution heat exchanger 16 by the solution pump 22 installed in the middle of the solution pipe 23. The refrigerant vapor separated from the concentrated solution is guided to the high-pressure absorber 24 via the eliminator 32. Heat source medium pipes 20 and 21 are connected to the heat exchanger 19.

  In the high pressure absorber 24, the solution concentrated in the high pressure regenerator 33 is sprayed from the spray unit 25 to the outside of the heat transfer tube of the heat exchanger 26. The sprayed solution absorbs the refrigerant vapor from the low-pressure regenerator 17 and decreases in concentration. Thereafter, the solution is led to the high pressure regenerator 33 through the high pressure side solution heat exchanger 31 by the solution pump 29 installed in the middle of the solution pipe 30. Cooling water is passed through the heat transfer tubes of the heat exchanger 26 in order to remove the absorbed heat generated when the solution absorbs the refrigerant vapor. Cooling water pipes 27 and 28 are connected to the heat exchanger 26.

  In the high pressure regenerator 33, the solution whose concentration has been reduced by the high pressure absorber 24 is sprayed from the spray unit 34 to the outside of the heat transfer tube of the heat exchanger 37. The sprayed solution is heated by a heat source medium flowing in the heat transfer tube of the heat exchanger 37 and separated into a concentrated solution and refrigerant vapor. The concentrated solution is guided to the high pressure absorber 24 through the high pressure side solution heat exchanger 31 by the solution pump 38 installed in the middle of the solution pipe 39. The refrigerant vapor separated from the concentrated solution is guided to the condenser 41 through the baffle 40. Heat source medium pipes 35 and 36 are connected to the heat exchanger 37.

  In the condenser 41, the refrigerant vapor separated from the high-concentration solution by the high-pressure regenerator 33 is cooled by the cooling water flowing in the heat transfer pipe of the heat exchanger 42 and is condensed and liquefied. The condensed and liquefied refrigerant is guided to the evaporator 1 through the refrigerant pipe 45. Cooling water pipes 43 and 44 are connected to the heat exchanger 42.

  As described above, the configuration of the present invention includes the low-pressure side cycle including the evaporator 1, the low-pressure absorber 9, and the low-pressure regenerator 17, the high-pressure absorber 24, the high-pressure regenerator 33, and the condenser 41. It is a two-stage absorption cycle consisting of a high-pressure side cycle. Usually, the solution circulating in the low pressure side cycle and the solution circulating in the high pressure side cycle are not mixed. On the other hand, the refrigerant moves in the order of the evaporator 1, the low pressure absorber 9, the low pressure regenerator 17, the high pressure absorber 24, the high pressure regenerator 33, and the condenser 41. Further, the internal pressure of the evaporator 1 and the low-pressure absorber 9, the low-pressure regenerator 17 and the high-pressure absorber 24, and the high-pressure regenerator 33 and the condenser 41 are the same.

  In this embodiment, an aqueous lithium bromide solution is used as the solution (absorbent), and water is used as the refrigerant.

  Next, a configuration according to the present invention will be described with reference to FIG.

  In the low pressure regenerator 17, a float type liquid level sensor 50 for detecting the liquid level of the solution accumulated at the bottom is installed. Further, the solution blow pipe 51 provided with the solution blow valve 52 is connected to the point A in the middle of the solution pipe 30 connected to the high pressure absorber 24 and the lower part of the low pressure regenerator 17.

  Next, operations and effects according to the present invention will be described.

  In the absorption refrigerator, the amount of refrigerant vapor generated in the evaporator 1 increases in proportion to the refrigerating capacity. Thereby, also in the low-pressure regenerator 17 and the high-pressure absorber 24 having the same pressure, the amount of refrigerant vapor generated in the low-pressure regenerator 17 increases, and the flow velocity of the refrigerant vapor passing through the eliminator 32 increases. At this time, in the low-pressure regenerator 17, the solution sprayed from the spray unit 18 flows down and out of the heat transfer tube of the heat exchanger 19 while being repeatedly attached and detached, and is heated by the heat source medium flowing in the heat transfer tube to generate refrigerant vapor. The concentrated solution is once stored in the lower part. Further, from the solution flowing down outside the heat transfer tube of the heat exchanger 19, since the outside of the heat transfer tube is repeatedly attached and detached, fine droplets are generated. At this time, it is considered that most of the generated droplets of the solution can be captured by the eliminator 32, but there is a possibility that fine droplets of the solution flow into the high-pressure absorber 24 along with the refrigerant vapor flow.

  In the two-stage absorption cycle, the solution circulating through the low pressure absorber 9 and the low pressure regenerator 17 in the low pressure side cycle and the solution circulating through the high pressure absorber 24 and the high pressure regenerator 33 in the high pressure side cycle are different. It is circulating in the route. For this reason, the amount of lithium bromide dissolved in the initially sealed solution does not change during operation. However, when fine droplets are generated during operation, the solution in the low-pressure regenerator 17 flows into the high-pressure absorber 24, and the balance of the lithium bromide amount changes from that at the time of encapsulation.

  Specifically, since the solution in the low pressure regenerator 17 flows into the high pressure absorber 24, the amount of lithium bromide on the low pressure cycle side decreases and the amount of lithium bromide on the high pressure cycle side increases. Thereby, in the low pressure regenerator 17, since the solution concentration is maintained, the amount of the refrigerant contained in the solution is reduced, and the amount of the solution circulating in the low pressure side cycle is gradually reduced. On the other hand, in the high pressure absorber 24, since the solution concentration is maintained, the amount of refrigerant contained in the solution increases, and the amount of solution circulating in the high pressure side cycle gradually increases. If these gradually progress, the solution of the low-pressure side cycle becomes insufficient, and the liquid level of the low-pressure regenerator 17 is lowered, and there is a possibility that the operation cannot be performed.

  Therefore, in this embodiment, a float type liquid level sensor 50 is provided below the low pressure regenerator 17. The detection data of the float type liquid level sensor 50 is sent to a control unit (not shown) to control the solution blow valve 52 of the solution blow pipe 51.

  In the control unit, a first predetermined value and a second predetermined value relating to the height of the liquid level are set in advance. The second predetermined value is set to be higher than the first predetermined value. As a result, when the liquid level of the solution in the low pressure regenerator 17 decreases and becomes lower than the first predetermined value, the solution blow valve 52 is opened by a signal from the control unit, and the solution in the high pressure side cycle is removed from the low pressure regenerator 17. Introduce in. On the other hand, when the liquid level of the solution reaches the second predetermined value, the solution blow valve 52 is closed by a signal from the control unit. Thereby, the liquid level height is adjusted within a range between the first predetermined value and the second predetermined value.

  With the above control, the amount of lithium bromide in the low-pressure side cycle and the high-pressure side cycle can be maintained appropriately. Therefore, even if the solution of the low-pressure regenerator 17 flows into the high-pressure absorber 24, the solution does not become insufficient in the low-pressure side cycle, and continuous operation can be performed.

  The evaporator 1 and the low-pressure absorber 9, and the high-pressure regenerator 33 and the condenser 41 have the same internal pressure, but have the same configuration and operation as those of a conventional single-effect cycle absorption refrigerator. Therefore, with the increase in the amount of refrigerant vapor generated in the evaporator 1, there is no problem that the continuous operation cannot be performed in the two-stage absorption cycle.

  FIG. 2 is an embodiment different from the first embodiment, and is obtained by modifying a portion surrounded by an elliptical broken line in FIG.

  In FIG. 2, a lower electrode bar 54 and an upper electrode bar 53 are provided in the low pressure regenerator 17 instead of the float type liquid level sensor 50 shown in FIG. The lower electrode bar 54 is installed at a liquid level corresponding to the first predetermined value, and the upper electrode bar 53 is installed at a liquid level corresponding to the second predetermined value.

  During operation of the absorption chiller, when it is detected that the liquid level of the solution in the low pressure regenerator 17 has dropped and the lower electrode bar 54 is not in contact with the accumulated solution, a control unit (not shown) The solution blow valve 52 of the solution blow pipe 51 is opened. On the other hand, when it is detected that the liquid level of the solution in the low-pressure regenerator 17 has risen and the upper electrode rod 53 has come into contact with the accumulated solution, the solution blow valve 52 of the solution blow pipe 51 is detected by a control unit (not shown). Close.

  By the above control, the same operations and effects as those of the first embodiment can be obtained.

  In addition, as the means for detecting the liquid level, the electrode rod is used in FIG. 2, but it is not limited to the electrode rod as long as the liquid level can be detected. For example, even a temperature sensor can be detected by the difference in temperature. The same operation and effect can be obtained.

  FIG. 3 is an embodiment different from the first and second embodiments, and is obtained by modifying a portion surrounded by an elliptical broken line in FIG.

  In FIG. 3, instead of the float type liquid level sensor 50 shown in FIG. 1, a diving weir 55 is provided on a wall that partitions the low pressure regenerator 17 and the high pressure absorber 24. Further, in order to cover the dive weir 55 and prevent the liquid droplet (solution mist) from flowing between the low pressure regenerator 17 and the high pressure absorber 24 through the gap portion above the dive weir 55, the mist blocking unit 56. Is provided.

  The height H of the dive weir 55 is the same as the liquid level height of the first predetermined value in the low-pressure regenerator 17 during the operation of the absorption chiller (similar to that shown in the first and second embodiments). Is set to the liquid level of the high-pressure absorber 24.

  Thereby, although it is different from the balance of the lithium bromide amount between the low-pressure cycle side and the high-pressure side cycle in the initial stage of filling, the low-pressure regenerator 17 ensures the minimum liquid level required for the operation of the absorption chiller. be able to.

  When the solution in the low-pressure regenerator 17 in the low-pressure side cycle flows into the high-pressure absorber 24 in the high-pressure side cycle, the amount of lithium bromide in the low-pressure side cycle gradually decreases. However, according to the present invention, the liquid level of the solution in the low pressure regenerator 17 is detected, and the solution in the high pressure side cycle flows into the low pressure side cycle. By controlling so that the reduced amount of lithium bromide can be recovered, continuous operation becomes possible.

  1: Evaporator 2, 10, 18, 25, 34: Spreading unit 3, 11, 19, 26, 37, 42: Heat exchanger, 4, 5: Cold water piping, 6: Refrigerant pump, 7, 45: Refrigerant piping, 8, 32: Eliminator, 9: Low pressure absorber, 12, 13, 27, 28, 43, 44: Cooling water piping, 14, 22, 29, 38: Solution pump, 15, 23, 30, 39: Solution piping, 16: Low pressure side solution heat exchanger, 17: Low pressure regenerator, 20, 21, 35, 36: Heat source medium piping, 24: High pressure absorber, 31: High pressure side solution heat exchanger, 33: High pressure regenerator 40: baffle, 41: condenser, 50: float type liquid level sensor, 51: solution blow piping, 52: solution blow valve, 53: upper electrode rod, 54: lower electrode rod, 55: submerged weir, 56: mist Blocking part.

Claims (6)

A low pressure side cycle including an evaporator, a low pressure absorber and a low pressure regenerator, and a high pressure side cycle including a high pressure absorber, a high pressure regenerator and a condenser,
The refrigerant vapor generated from the low-pressure regenerator has a configuration that is absorbed by the solution of the high-pressure absorber,
An absorption refrigerator that controls the liquid level of the solution stored at the bottom of the low-pressure regenerator to be maintained at a predetermined value or higher.   The absorption refrigerator according to claim 1, wherein when the liquid level becomes equal to or lower than a predetermined value, control is performed to introduce the solution of the high-pressure side cycle into the low-pressure regenerator.   2. The absorption refrigeration according to claim 1, wherein control is performed to introduce or stop introduction of the solution of the high-pressure side cycle into the low-pressure regenerator so that the liquid level is maintained within a predetermined range. Machine. The predetermined range is a range between a first predetermined value and a second predetermined value, and the second predetermined value is set higher than the first predetermined value,
At the bottom of the low pressure regenerator, a liquid level detection unit for detecting the liquid level height is attached,
When the liquid level detection unit detects that the liquid level is equal to or lower than the first predetermined value, the valve of a bypass pipe that sends the solution from the high pressure absorber to the low pressure regenerator is opened, The absorption refrigerator according to claim 3, wherein when the liquid level height reaches the second predetermined value by the detection unit, the valve is controlled to close. The wall that partitions the low-pressure regenerator and the high-pressure absorber is provided with a submerged weir,
4. The structure according to claim 1, wherein when the liquid level of the solution stored at the bottom of the high pressure absorber becomes higher than the diving weir, the solution of the high pressure absorber flows into the low pressure regenerator. The absorption refrigerator according to claim 1.   The absorption chiller according to claim 5, wherein a mist blocking portion is provided above the diving weir.

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