JPH1026432A - Absorption freezer and its operation method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an absorption freezer and its operation method where outlet cold water temperature can be set at 4 deg.C. SOLUTION: An absorption freezer R is adapted such that a freezer body is made compact to improve responsiveness, and the body is kept at high vacuum and digital control is executed to sharply improve stability of temperature for prevention of freezing of a refrigerant whereby cold water Wc is taken out at 4 deg.C. Further, an operation method of the absorption freezer R is achieved by keeping pressure of a cold water production part 10 at 4.6mmHg to 6.5mmHg.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an absorption refrigerator and a method for operating the absorption refrigerator. More specifically, the present invention relates to an absorption refrigerator capable of extracting cold water at about 4 ° C. and a method of operating the absorption refrigerator.

[0002]

2. Description of the Related Art Conventionally, an absorption refrigerator using water as a refrigerant has been used in an air conditioning or chemical plant. Since water is used as a refrigerant in such an absorption refrigerator, the outlet cold water temperature (cold water removal temperature) of the absorption refrigerator is normally controlled at 7 ° C., and the temperature of the refrigerant becomes 0 ° C. Thus, it is possible to avoid the trouble that the refrigerant is frozen. In addition, recently, the use of the control device for controlling the outlet chilled water temperature to 5 ° C. has been found to be used for a special purpose because of the improvement of the responsiveness of the control device.

On the other hand, in an electric turbo refrigerator used in a chemical process or the like, since there is no problem that the refrigerant freezes at 0.degree. C. or lower, for example, to about 4 ° C.

However, in recent years, it has been pointed out that the problem of destruction of the ozone layer by Freon gas has been pointed out as a problem, and the use of Freon gas as a refrigerant has been regulated. Therefore, replacement of the electric turbo refrigerator with an absorption refrigerator has been studied. In this case, it is necessary to set the outlet chilled water temperature of the absorption refrigerator to 4 ° C. as in the electric turbo absorption refrigerator.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in consideration of the above-mentioned problems in the prior art, and has as its object to provide an absorption refrigerator capable of controlling the outlet chilled water temperature to 4 ° C. and a method of operating the absorption refrigerator. I have.

[0006]

Means for Solving the Problems As a result of intensive studies on the problems of the prior art, the present inventors have improved the responsiveness by making the absorption chiller compact, and at the same time, maintained it in a high vacuum to perform digital control. By doing so, it has been found that the stability of the temperature in the absorption refrigerator is remarkably improved, thereby preventing the refrigerant from freezing, and finding that cold water can be taken out at 4 ° C., thereby completing the present invention.

That is, in the absorption refrigerator of the present invention, the outlet chilled water temperature of the absorption refrigerator is set to 4 ° C. to 5 ° C., or the pressure of the chilled water generator is set to 4.6 mmHg to 6.5 mmH.
g.

More specifically, an absorption refrigerating machine according to the present invention has a hermetically sealed structure comprising a cold water generating section, an absorbent regenerating section, a degassing section, and a control section. A chilled water generator, which is provided with a well-drained refrigerant spraying means and a deaeration line connected to a deaeration unit, and the absorbent that has absorbed the refrigerant in the absorbent regeneration unit is heated from a low temperature regenerator to a high temperature. Equipped with a reverse system to flow the regenerator to regenerate the absorbent,
The degassing unit is equipped with an automatic degassing mechanism that automatically degass gas not absorbed by the absorbent, and the pressure of the cold water generating unit is 4.6 mmH.
g to 6.5 mmHg.

[0009] In the absorption refrigerator of the present invention, it is preferable that the pressure of the cold water generating section is maintained at 5.0 mmHg to 5.5 mmHg.

In the absorption refrigerator of the present invention, when a high-performance pipe is used as the evaporator pipe of the evaporator of the chilled water generator, the load range is 40% to 100%, and the cooling water inlet temperature is reduced. Is preferably 32 ° C. to 28 ° C., and when a bare pipe is used, the load range is 20% to 100%, and the cooling water inlet temperature is 32 ° C.
Preferably, the temperature is set to ２２22 ° C.

On the other hand, an operation method of an absorption refrigerator according to the present invention is directed to an absorption refrigerator having a closed structure including a chilled water generator, an absorbent regenerating unit, a degassing unit, and a control unit. Operating method, wherein a predetermined amount, for example, 1/2, of the absorbent absorbing the refrigerant in the absorbent regenerating section is reversely regenerated from the low temperature regenerator to the high temperature regenerator, and the absorption present in the cold water generating section is performed. Gas not absorbed by the agent is removed by a degassing section, and the pressure of the cold water generating section is maintained at 4.6 mmHg to 6.5 mmHg, preferably 5.0 mmHg to 5.5 mmHg.

In the operation method of the absorption refrigerator according to the present invention, when a high-performance pipe is used as the evaporator pipe of the evaporator of the chilled water generator, the load range is from 40% to 100%.
%, And the cooling water inlet temperature is preferably 32 ° C. to 28 ° C. When a bare pipe is used, the load range is 20% to 100%, and the cooling water inlet temperature is 32 ° C. to 32 ° C. Preferably, the temperature is 22 ° C.

[0013]

Since the absorption refrigerator of the present invention is constructed as described above, it is possible to stably take out cold water of about 4 ° C.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described based on embodiments with reference to the accompanying drawings, but the present invention is not limited to only such embodiments.

FIG. 1 is a schematic diagram of an embodiment of the absorption refrigerator of the present invention, and FIG. 2 is a block diagram of the absorption refrigerator. The absorption refrigerator R includes a chilled water generator 10 and an absorbent regenerating unit 20. , A deaeration unit 30 and a control unit (not shown) as main components, and these units are connected to each other by required piping equipment (line) 40.

The chilled water generator 10 includes a chilled water generator section 12 having an evaporator 11 and a refrigerant absorption section 16 having an absorber 15. The evaporator tube has a heat transfer area, for example. In order to increase the diameter, a so-called high-performance tube having a fin-shaped barb or groove formed on the outer surface of the tube, or a bare tube without any processing on the outer surface of the tube is used. Then, the cold water generating section 12, while the cold water flows through the evaporator inside the tube, the refrigerant is sprayed by the refrigerant spraying means 13 to the evaporator tubes outside, it heat exchange between the refrigerant and the cold water W _C is performed by evaporator The chilled water W _{C at the} outlet 11 is cooled to a predetermined temperature (in the range of 4 ° C. to 5 ° C.), and a part of the refrigerant is evaporated and supplied to the refrigerant absorption section 16.

In the case of using this high-performance pipe, since the amount of refrigerant retained on the surface of the evaporator pipe is large, even if the refrigerant spraying means 13 with good drainage is used, the evaporator can be used even after the refrigerant pump 41a is stopped. Since the cold water is cooled by the refrigerant held in the tube and the temperature of the cold water is lowered, the use range of the absorption refrigerator is more restricted than when a bare tube is used.

Then, cold water W cooled to a predetermined temperature
_C is taken out from the absorption refrigerator R and supplied to the use destination, and the refrigerant is supplied to the refrigerant distribution means 13 by the refrigerant pump 41a provided in the circulation line 41. Here, the coolant spraying means 13 has a structure according to Japanese Patent No. 988359, for example, in order to prevent the coolant from being supercooled and frozen (frozen) in order to prevent so-called drainage. Further, the degree of vacuum (4.6 mmHg to 6.5 mmH) corresponding to the vapor pressure of the refrigerant of about 2 ° C.
g, preferably 5.0 mmHg to 5.5 mmHg), the container constituting the cold water generating unit 10 has a welded structure.

The vaporized refrigerant (refrigerant vapor) supplied to the refrigerant absorbing section 16 is absorbed by the absorbent (spray concentrated liquid) sprayed outside the absorber 15 in which the cooling water is flowing. You. The absorbent (hereinafter, simply referred to as a dilute liquid) that has absorbed and diluted the refrigerant vapor is provided in the first regeneration line 42 that connects the refrigerant absorption section 16 and the absorbent regeneration section 20. The water is supplied to the absorbent regenerating section 20 by a pump for diluted liquid (dilute liquid pump) 42 a, and a part thereof is branched by a diluted liquid branch line 43 and supplied to the deaeration section 30. The temperature of the diluted liquid supplied to the absorbent regeneration unit 20 is increased by a low-temperature heat exchanger 42b disposed downstream of the diluted liquid pump 42a and supplied to the absorbent regeneration unit 20.

When the refrigerant evaporates, the gas dissolved in the refrigerant is released to the chilled water generator 10. The released gas communicates the refrigerant absorption section 16 with the deaerator 30. The deaeration line 44 also removes air leaked from the outside into the cold water generator 10 and non-condensable gas that is not absorbed by the absorbent, such as hydrogen gas generated by the formation of an oxide film.
This prevents a decrease in the degree of vacuum of the cold water generator 10.

The absorbent regenerating section 20 is composed of a first regenerating section (low-temperature regenerating section) 21 and a second regenerating section (high-temperature regenerating section) 27, and the dilute liquid from the first regenerating line 42
Supplied to The first regenerating unit 21 includes a low-temperature regenerator 22
And a condensing section 25 having a condenser 24. The diluent is supplied to a liquid inflow pipe 26 provided in the regenerating section 23.
Is sprayed outside the low temperature regenerator tube. On the other hand, inside the low-temperature regenerator tube, high-temperature refrigerant vapor (hereinafter, referred to as high-temperature vapor) regenerated from a second regenerating unit 27 described later is supplied via a high-temperature vapor line 45. Therefore, part of the refrigerant absorbed in the rare liquid is regenerated and released as low-temperature refrigerant vapor (hereinafter, referred to as low-temperature vapor). The discharged low-temperature steam is condensed by the condenser 24 in the condensing section 25 to be water, and is in a state usable for cooling the cold water W _C. That is, the refrigerant liquid is regenerated. The condensing section 25 is also supplied with a high-temperature steam that has been drained by heating the rare liquid in the low-temperature regenerator 21 and a refrigerant liquid that has been regenerated from the high-temperature steam. The refrigerant liquid regenerated from the low-temperature vapor and the high-temperature vapor is supplied to the refrigerant distribution means 13 through the refrigerant supply line 46.
On the other hand, a predetermined amount, for example, half, of an absorbing liquid (hereinafter, referred to as an intermediate liquid) having a concentration increased by releasing a part of the refrigerant is the second liquid that connects the first regeneration unit 21 and the second regeneration unit 27. Absorption liquid pump (intermediate liquid pump) provided in regeneration line 47
The signal is supplied to the second reproducing unit 27 by 47a. The intermediate liquid is heated by a high-temperature heat exchanger 47b disposed downstream of the intermediate liquid pump 27a, and
Supplied to

The second regenerating section 27 includes a high-temperature regenerator 28 into which heating steam is supplied.
Heats the intermediate liquid, whereby the refrigerant absorbed in the intermediate liquid is released as high-temperature vapor, and the concentration of the absorbent increases. The released high-temperature steam is supplied to the low-temperature regenerator 21 and used for heating the dilute liquid as described above. On the other hand, an absorbing solution with an increased concentration (hereinafter referred to as a concentrated solution)
Is supplied to the high-temperature heat exchanger 47b through the concentrated liquid line 48 that connects the second regeneration unit 27 and the high-temperature heat exchanger 47b.

The concentrated liquid supplied to the high-temperature heat exchanger 47b exchanges heat with the intermediate liquid to raise the temperature of the intermediate liquid, and is then mixed with the remaining intermediate liquid supplied from the intermediate liquid supply line 49. This mixed liquid (spray concentrated liquid) is supplied to the low-temperature heat exchanger 42b and exchanges heat with the dilute liquid. Then, the mixed liquid (spray concentrated liquid) is sprayed to the absorber 15 of the refrigerant absorption section 16 by the spray concentrated liquid line 50. The refrigerant vapor evaporated in the generation section 12 is absorbed.

The deaeration unit 30 prevents the air leaked from the outside and the iron part of the chilled water generation unit 10 by the ejector effect of the diluted liquid branched from the downstream side of the diluted liquid pump 42a of the first regeneration line 42. Non-condensable gas that is not absorbed by the absorbent such as hydrogen gas generated when the rust film is formed is automatically degassed. This deaeration unit 30 is specifically described in Japanese Patent No.
No. 200207. The diluted liquid used by the deaeration section 30 is supplied to the deaeration line 5.
1 returns to the refrigerant absorption section 16.

The control unit uses digital PID control to relatively quickly and stably follow load fluctuations and cooling water inlet temperature changes so as not to cause a large overshoot. This digital PID control is, specifically, an absorption refrigerator R whose operation amount is a continuous type and which is a control target.
In this case, a continuous type that does not cause a large disturbance is adopted, and the sampling interval Δt at that time is selected sufficiently finely in comparison with the speed of change of the signal. An arithmetic expression relating to this control is represented by, for example, the following expression.

[0026]

(Equation 1)

Further, in this embodiment, the joint of each line has a welded structure and the pump provided on each line has a sealed structure, and gas enters the system from the joint and the pump. Has been prevented. In addition, various viewing windows that have been conventionally used have been abolished.

As described above, in this embodiment,
In the regenerating section, a so-called reverse method is used, in which the absorbing liquid flows from the low-temperature regenerating section to the high-temperature regenerating section, so that the regenerating section is downsized, and the responsiveness is improved by using a so-called good-spraying means in the cold water generating section. Prevents cooling, has a closed structure for each part, and adopts fully automatic bleeding to automatically deaerate the chilled water generator (removal of non-condensable gas) to maintain a high degree of vacuum and properly control by digital PID control. Is performed, the temperature stability is dramatically improved, and cold water can be stably taken out at about 4 ° C.

[0029]

Hereinafter, the present invention will be described in more detail with reference to more specific examples.

Example 1 Using an absorption refrigerator using a high-performance tube as an evaporator tube of a chilled water generation unit (manufactured by Kawaju Cooling Industrial Co., Ltd .: Sigmachill 600 type absorption refrigerator), load fluctuation in practical operation was reduced. A simulation test was performed to simulate a violent state, increase and decrease the load at a rate of 10% / min, and increase and decrease the temperature of the cooling water at a rate of 1 ° C./min to obtain a stable range of 4 ° C. cold water. . As a result, 4 ° C. cold water could be taken out stably when the load was in the range of 40 to 100% and the cooling water inlet temperature was in the range of 32 to 28 ° C. When the load was 40% and the cooling water inlet temperature was 22 ° C., 4 ° C. cold water could not be taken out stably. When the load was 30% and the cooling water inlet temperature was 22 ° C., the safety device was activated due to the low cooling water temperature.

Example 2 Using an absorption refrigerating machine using a bare tube as an evaporator tube of a chilled water generation unit (manufactured by Kawaju Cooling Industrial Co., Ltd .: Sigmachill 600 type absorption refrigerating machine), the load fluctuates drastically in practical operation. Simulating the state, the load was increased / decreased at a rate of 10% / min, and the temperature of the cooling water was increased / decreased at a rate of 1 ° C./min. As a result, 4 ° C. cold water could be stably taken out under a load of 20 to 100% and a cooling water inlet temperature of 32 to 22 ° C.

[0032]

As described in detail above, according to the present invention,
An excellent effect that cold water of about 4 ° C. can be stably taken out from the absorption refrigerator is obtained. Therefore,
This makes it possible to replace the electric turbo refrigerator with an absorption refrigerator.

[Brief description of the drawings]

FIG. 1 is a schematic view of an embodiment of an absorption refrigerator of the present invention.

FIG. 2 is the same block.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 Cold water generation part 11 Evaporator 12 Cold water generation section 15 Absorber 16 Refrigerant absorption section 20 Absorbent regeneration part 21 1st regeneration part (low temperature regeneration part) 22 Low temperature regenerator 23 Regeneration section 24 Condenser 25 Condensing section 27 2nd regeneration Section (high-temperature regeneration section) 28 high-temperature regeneration section 30 deaeration section 40 required piping equipment R absorption refrigerator W _C cold water

Claims (10)

[Claims] 1. The temperature of chilled water at the outlet of an absorption refrigerator is 4 ° C. to 5 ° C.
An absorption type refrigerator characterized by being at a temperature of ° C. 2. The pressure of a chilled water generator of an absorption refrigerator is 4.
An absorption refrigerator characterized by being maintained at 6 mmHg to 6.5 mmHg. 3. An absorption refrigerating machine having a closed structure including a chilled water generator, an absorbent regenerating unit, a deaerator, and a controller, wherein the chilled water generator has a drainable refrigerant. A reverse system comprising a spraying means and a deaeration line connected to a deaeration unit, and a system in which the absorbent that has absorbed the refrigerant in the absorbent regeneration unit flows from the low-temperature regenerator to the high-temperature regenerator to regenerate the absorbent. The degassing section is provided with an automatic degassing mechanism for automatically degassing gas not absorbed by the absorbent, and the pressure of the cold water generating section is maintained at 4.6 mmHg to 6.5 mmHg. Type refrigerator. 4. The pressure of the cold water generating section is 5.0 mmHg or more.
The absorption refrigerator according to claim 2 or 3, wherein the absorption refrigerator is maintained at 5.5 mmHg. 5. The absorption refrigerator according to claim 1, wherein a high-performance tube is used as an evaporator tube of the evaporator of the chilled water generator, wherein the load range is 40% to 100%. An absorption refrigerator having a cooling water inlet temperature of 32C to 28C. 6. The absorption refrigerator according to claim 1, wherein a bare pipe is used as an evaporator pipe of the evaporator of the chilled water generator, wherein the load range is 20% to 100%, and An absorption refrigerator having a cooling water inlet temperature of 32C to 22C. 7. An operating method of an absorption refrigerating machine having a closed structure including a chilled water generating section, an absorbent regenerating section, a degassing section, and a control section, wherein the absorbent regenerating section includes: A predetermined amount of the absorbent absorbing the refrigerant is reversely regenerated from the low-temperature regenerator to the high-temperature regenerator, and the gas not absorbed by the absorbent present in the cold water generating section is removed by the degassing section. A method for operating an absorption refrigerator, wherein the pressure is maintained at 4.6 mmHg to 6.5 mmHg. 8. The pressure of the cold water generating section is set to 5.0 mmHg or more.
The method according to claim 7, wherein the pressure is maintained at 5.5 mmHg. 9. An absorption refrigerator in which a high-performance tube is used as an evaporator tube of an evaporator in a chilled water generator, the load range is 40% to 100%, and the cooling water inlet temperature is 3%.
9. The temperature is set to 2 [deg.] C. to 28 [deg.] C.
The operation method of the absorption refrigerator described above. 10. An absorption refrigerator in which a bare pipe is used as an evaporator pipe of an evaporator in a chilled water generator, the load range is 20% to 100%, and the cooling water inlet temperature is 3%.
The temperature is set to 2 ° C to 22 ° C.
The operation method of the absorption refrigerator described above.