JPH04203858A - Absorption type refrigerating machine - Google Patents

Abstract

PURPOSE:To permit the operation of a refrigerating machine even when the temperature of cooling water is high by a method wherein one part of absorbing solution is sent into an absorber after distilling refrigerant by an evaporator and the balance of the same is sent into a condenser to contact it with vapor from a reproducer to effect absorption cooling and circulate it between the evaporator and the condenser. CONSTITUTION:Vapor, generated from a reproducer 1, is introduced into a condenser 2 and is mixed with the other vapor generated by spraying concentrated weak liquid obtained by an evaporator 3 to effect absorption condensation. Concentrated strong liquid, obtained by absorption condensation, is sent into the evaporator 3 through a concentrated liquid heat exchanger 6 and, thereafter, refrigerant vapor is sent into an absorber 4. Hot brine is cooled by the latent heat of evaporation of the refrigerant to obtain low-temperature brine. The weak liquid, from which the refrigerant obtained by the evaporator 3 is removed, is returned to the condenser 2. The diluted weak liquid from the reproducer 1 is mixed with the vapor from the evaporator 3 in an absorber 4 and condensing heat is removed by cooling water in the group of cooling pipes to remove condensing heat and obtain the diluted strong liquid while the diluted strong liquid is sent into the reproducer 1 to complete an absorption cycle whereby high-temperature heat, fed to the heater of the reproducer 1, is taken out of the evaporator 3 as the low-temperature heat source and a refrigerating system can be completed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an absorption refrigerator that performs a heat exchange operation by changing the entropy of the refrigerant using an absorption liquid that absorbs the refrigerant.

[Prior Art] In a heat pump that uses water as a refrigerant and inorganic salts as an absorbent, typified by water lithium bromide, a proposal was made in 1984 to mix the refrigerant from the evaporator and the absorption liquid in the condenser.
It was carried out by Kokai (1) et al. This proposal is unique in that it aims to increase thermal efficiency by changing the type of absorbent used in the evaporator/condenser circulation cycle and the regenerator/absorber circulation cycle. This proposal also holds true even if the same absorbent is used instead of the different absorbents A and B. In 1987, Iezai (2) et al. announced the performance of the above-mentioned heat pump using the same absorbent in the water lithium bromide system.

However, unlike heat pumps, the present invention uses water as a refrigerant and an inorganic salt as an absorbent.
This article describes a method of sending the liquid from the evaporator to the condenser and circulating it between the two in an absorption refrigerator using aqueous ammonia, chlorofluorocarbons, organic solvents, etc.

[Problems to be Solved by the Invention] The present invention has no lower limit on the temperature of the water to be cooled unlike steam water lithium bromide, has better thermal economy than the water ammonia system, and has a heat source and cooling water that can be used. The purpose is to use an absorption chiller that can be operated even under mild operating conditions. Furthermore, this method allows for the first time to economically and industrially apply multi-component refrigerants having a vapor-liquid equilibrium relationship, which are currently being newly developed.

[Means for Solving the Problems] In the absorption refrigerator according to the present invention, after distilling the refrigerant in the evaporator, a part of the absorption liquid (thick weak liquid) is sent to the absorber, and the remaining part is sent to the condenser. There, it is characterized in that it is brought into contact with the vapor from the regenerator for absorption cooling, the resulting liquid (thick strong liquid) is sent to the evaporator, and this absorbed liquid is circulated between the evaporator and the condenser.

[Effects (1) The condensation temperature in the condenser is such that when mixed with the evaporated liquid,
Absorption condensation occurs at high temperatures, which has the following advantages:

If the operating pressure is the same as in the conventional method, the condensation temperature of the condenser will be high, and the refrigerator can be operated even if the temperature of the cooling water is high. Furthermore, if the condensation temperature is the same as that of the conventional method, the operating pressure will be lower, the heating temperature of the regenerator may be lower, and a heat source with a lower temperature can be used. Furthermore, since the operating pressure of the regenerator is low, it is possible to design inexpensive equipment. (Tables 1 and 2) (2) There is no need to evaporate pure refrigerant in an evaporator, so there are the following advantages.

Since pure refrigerant does not need to be used in the evaporator, there is no need for rectification with reflux in the regenerator, simplifying the arrangement of the equipment.

(3) The pressure difference between the regenerator and condenser operating at high pressure and the evaporator and absorber operating at low pressure becomes smaller due to the reason in (1), and the power of the circulation pump can be reduced. .

(Table 3) Table 2. Regenerator operating pressure vs. condensing temperature Table 3. Pressure difference vs. condensing temperature (1) Yasuo Kokai: Abstracts of the 18th Autumn Conference of the Japan Chemical Industry Association, 249, [Example] The regenerator 1 has a heater, and the The resulting dilute weak liquid is distilled to generate vapor, which is sent to the next condenser 2. On the other hand, the weak liquid obtained by the generator, that is, the diluted weak liquid in which the refrigerant has become diluted, is returned to the absorber 4. At this time, heat exchange between the thin and thin chord waves is performed through the heat exchanger 7. The vapor generated from the regenerator 1 is led to the condenser 2, where the concentrated weak liquid, that is, the concentrated weak liquid obtained by the evaporator 3, falls on a group of heating tubes for cooling, and is mixed with the generated vapor and absorbed. Let condensation take place. The obtained concentrated strong liquid is sent to the evaporator 3 through a concentrated liquid heat exchanger 6. In the evaporator 3, evaporation, or in the case of phase equilibrium, distillation or rectification is performed by heating with return hot brine, and the refrigerant vapor is sent to the absorber. The hot brine is cooled by the latent heat of vaporization of the refrigerant to obtain a cold brine. The weak liquid obtained in the evaporator from which the refrigerant has been removed is returned to the condenser as described above.

In the absorber 4, the dilute weak liquid from the regenerator and the vapor from the evaporator are mixed, and the cooling pipe group removes the heat of condensation with cooling water to obtain a dilute sinusoidal wave, which is sent to the regenerator for an absorption cycle. The high-temperature heat supplied to the regenerator heater is extracted as a low-temperature heat source by the evaporator, completing the refrigeration system.

The above operations are performed at high pressure for regeneration and condensation, and at low pressure for absorption and evaporation. For this purpose, circulation is carried out by transport pumps from the low-pressure side to the high-pressure side, ie the dilute liquid circulation pump 8 and the concentrated liquid circulation pump 5.

When using a water-ammonia type refrigerant, high-temperature cooling water (30 to 40°C) or low-temperature heat source (80°C) is used.
to 120°C) and cool brine (5°C to 120°C) in an evaporator.
to -30℃), 100% as before.
Instead of obtaining a refrigerant close to 100%, it is necessary to use a refrigerant with a lower purity, i.e., about 70 to 90%, and operate the evaporator at low pressure (1 to 5 kg 17 cm2) and low temperature (10 to -30°C). be. At this time, warm brine is used to heat the evaporator and the brine is cooled.

Since the vapor from the regenerated liquid has a high concentration (90 to 9996), it is necessary to condense it. However, a condenser using ordinary cooling water cannot be operated because the condensation temperature is low even if the operating pressure is increased. for that,
The condensation operation is different from the conventional method, and it is important to use a dilute weak liquid in the method regenerator of the present invention to increase the condensation temperature by absorption condensation. At this time, heat exchange is performed between the concentrated strong liquid and the concentrated weak liquid circulating between the evaporator and the condenser. This increases the evaporation power (refrigeration capacity) and brings the liquid supplied to the evaporator closer to the boiling temperature of the evaporator, resulting in thermal economy. The concentration of the concentrated strong liquid from the condenser thus produced is 80-97%.
The vapor from the evaporator is concentrated in the absorber. It is distilled or evaporated in the regenerator, but unlike conventional absorption refrigerators, the regenerator does not require reflux because it does not need to obtain pure refrigerant. By sending the refrigerant to the absorber, the overall material balance can be maintained, which improves the thermal economy.The refrigerant vapor in the regenerator is sent to the condenser, and the dilute weak liquid obtained as condensate is returned to the absorber. is the same as a normal absorption refrigerator cycle.

In order to compare the embodiment according to the present invention as shown in FIG. 1 with a conventional water ammonia absorption refrigerator, the system according to the present invention as shown in FIG. In the example, water-ammonia is used at low temperature-2
Various numerical values when the operating conditions were evaporation temperatures of 8 to -29°C are listed in the column of Example 1 below. The coefficient of performance of a normal water-ammonia system is 0.420, but since reflux is not performed with this method, the coefficient of performance is 0°512.
and has improved.

In order to make a comparison between the embodiment of the present invention as shown in FIG. Various numerical values for comparison with the case of the chilled water device used are listed in the column of Example 2. The coefficient of performance is almost the same.

However, what is important here is that even if a water ammonia system is used, there is no need for reflux as mentioned above, so the operation is easy.
Cold water below 0°C can be easily obtained. Another advantage is that by using a new multi-component refrigerant, the range of application of absorption refrigerators can be expanded.

Concentrated liquid circulation pump, plunger type 5001 /
ht A supercooler 10 is provided between the evaporator 3 and the absorber 4, and a supercooler 10 is provided between the evaporator 3 and the absorber 4 to heat the refrigerant vapor generated in the regenerator 1 as a heat source.
An embodiment of the present invention is shown in which the refrigerant vapor generated in the evaporator 3 is cooled using the absorption liquid cooled therein as a cold heat source.

As shown in FIG. 3, the present invention can be applied to a first-class heat pump that uses a high-temperature heat source to raise a low-temperature heat source to an intermediate temperature. In this application, the regenerator and condenser are at high pressure and the generator and absorber at low pressure, similar to absorption chillers.

The advantage of the present invention is that unlike the conventional method in which pure refrigerant is obtained by circulating the evaporated liquid to the condensate and then evaporated, the condensation temperature is increased by the concentrated weak liquid from the evaporator without increasing the condensing pressure. is higher, which is advantageous for heating a low-temperature source, that is, it is possible to obtain higher-temperature medium-temperature water and to reduce the heat transfer area.

Application to Type 2 Heat Pumps: Conventionally, heat pumps using refrigerants with high vapor pressure have been limited to so-called Type 1 heat pumps.

This was considered uneconomical if an attempt was made to create a type 2 cycle using pure refrigerant, as both the regenerator and evaporator would be at high pressure, making the high-pressure equipment expensive. For example, when a heat source of 60 to 80 degrees Celsius is used and cooling water of 25 to 30 degrees Celsius is used to create a second type heat pump, and a pure refrigerant of the conventional method is used, the pressure of the evaporator is 40 to 60 degrees Celsius. kgl/cm2]
, evaporator flow is 17 to 19 [kgl/cm”
] Therefore, as a system for obtaining a heat source of 110 to 120° C., the equipment becomes expensive and cannot be said to be economical. The above values are for water-ammonium type refrigerants, but even if other refrigerants are used, it is necessary to use refrigerants with high vapor pressure in order to recover the heat source from low temperatures, and this tendency is unavoidable.

In an embodiment of the invention as shown in FIG.
The ammonia concentration in the evaporator operated at a pressure of [kgl/cm2] is 51%, and the ammonia concentration at the top of the column is 55.
5% and 75°C. In the absorber, which is supplied with the diluted liquid sent from the regenerator, the condensation temperature is 114° C., and high-temperature hot water can be recovered. When operating the regenerator, the temperature at the bottom of the column is 77°C and the temperature at the top is 68°C.
It is being driven in C. The ammonia concentration at this time was 28.4% at the bottom of the column and 32% at the top. The vapor from this regenerator is sent to the condenser where it is mixed with the weak liquid coming from the bottom of the evaporator where absorption and condensation takes place at 30°C. The concentration of the liquid obtained here is 55.5%, and this is returned to the evaporator. By supplying the weak liquid from the evaporator to the condenser, a second type of heat pump can be constructed using ordinary cooling water (not particularly cold water).

In an embodiment of the present invention constituting a type 2 heat pump using R22-DMF as the refrigerant, a heating source of 25 to 30°C is used with an evaporation temperature of 10°C, a heating source of 15°C, and a condensing temperature of -10°C. When the concentration of R22 was 90%, the operating pressure of the evaporator was 5al, and the evaporation temperature was 1.
Assuming 0°C, a condensation temperature of 25°C is obtained in the absorber. The condensate concentration at this time was 7396, the temperature at the bottom of the regenerator was 10°C, and the R22 concentration at that time was 7196.

As described above, when the present invention is applied to a second type heat pump, cold cooling water is not particularly required, so that an economical second type heat pump can be constructed.

FIG. 5 shows an example of a flow sheet for industrial use of the present invention.

[Effects of the invention] (1) Since the condenser absorbs and condenses a concentrated weak liquid, the condensing pressure decreases and the design pressure can be set lower than the operating pressure of the conventional type, making it possible to manufacture an economical device. be.

(2) It has traditionally been difficult to obtain cold water at low temperatures (below 0°C to 5°C) using water lithium bromide absorption refrigerators, and there has been a demand for new development of absorption refrigerators. According to the method, since the condenser absorbs and condenses the concentrated weak liquid, (a) the thermal efficiency is improved, (b) the heating temperature of the regenerator is low, and (c) the refrigerant is condensed even if the temperature of the cooling water is high. It is possible to provide an absorption chiller that has the following advantages.

(3) In this method, by using a refrigerant-absorbent system such as a water ammonia system or a multi-component system such as fluorocarbons and an organic solvent, an absorption refrigerator can efficiently perform absorption cooling over a wide temperature range. In other words, when using a refrigerant with vapor-liquid equilibrium, such as the water-ammonium system, for refrigeration, obtaining a highly concentrated refrigerant was a condition for obtaining a low temperature.
If the evaporation temperature is 5 to -30°C (if a temperature higher than -30°C is required, a highly pure refrigerant may be required), the evaporator can be heated by appropriately selecting the refrigerant concentration. The temperature control is good and the above low temperature can be obtained. Therefore, in the refrigeration system represented by aqueous ammonia, the following conditions, which have been striving to obtain high purity ammonia, are no longer necessary.

(a) A high reflux ratio (not necessary) (b) A high heating pressure is required (not necessary) (c) A low cooling water temperature (it can be high) (4) New multi-component refrigerant This system is fully applicable to these situations. In other words, there is no need to obtain pure refrigerant, so for example, in the case of R22 and DMF, there is a dilute liquid equilibrium, and conventional systems required high pressure and low temperature cooling water to liquefy R22, but this method According to the method, since a refrigerant mixed with DMF is used, the desired purity can be obtained by a simple distillation operation. In this way, an efficient absorption refrigerator can be provided by combining distillation or rectification column operations that are suited to the properties of the refrigerant. Therefore, it is thought that the development of multi-component absorption refrigerants without ozone depletion ability will progress in the future, and the application of this system will become even more widespread.

(5) The function as a heat pump can be easily operated over a wide range of motion by using an appropriate refrigerant.

(6) The problem of corrosion, which was a problem with water lithium bromide, can be solved by using a multi-component refrigerant.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram showing a basic embodiment of the present invention, Fig. 2 is a schematic diagram showing an embodiment of the present invention in which a vapor heater and a supercooler are added, and Fig. 3 is a schematic diagram showing a basic embodiment of the present invention. FIG. 4 is a schematic diagram showing an embodiment of the present invention constituting a type 1 heat pump; FIG. 4 is a schematic diagram showing an embodiment of the present invention constituting a type 2 heat pump; FIG. 5 is a schematic diagram showing an embodiment of the present invention constituting a type 2 heat pump; FIG. Schematic diagram showing an embodiment of the present invention in the case of: 1--regenerator, 2-- condenser, 3-- evaporator, 4--
...Absorber, 5.. Concentrated liquid circulation pump, 6.. Concentrated liquid heat exchanger, 7. Dilute liquid heat exchanger, 8.. Dilute liquid circulation pump, 10.. Supercooler, 11..・Vapor heater.

Claims (3)

[Claims] (1) Heating the absorption liquid that absorbs the refrigerant and distilling the refrigerant from the absorption liquid from the absorber in absorption refrigeration machines with vapor-liquid equilibrium and using refrigerant-absorbent. A regenerator, a condenser that condenses the refrigerant vapor generated in the regenerator, and a refrigerant obtained by heating and distilling the refrigerant liquefied by the condenser with brine to the absorber, where it is cooled. In an absorption refrigerator, which has an evaporator that obtains brine and an absorber that brings the refrigerant vapor generated in the evaporator into contact with an absorption liquid from a regenerator to absorb and cool the refrigerant into the absorption liquid, the refrigerant is absorbed by the evaporator. After distillation, a part of the absorption liquid (concentrated weak liquid) is sent to the absorber, and the rest is sent to the condenser, where it is brought into contact with vapor from the regenerator for absorption cooling, and the obtained liquid (
An absorption refrigerator characterized by sending a concentrated strong liquid to an evaporator and circulating the absorbed liquid between the evaporator and the condenser. (2) An absorption refrigerating machine according to claim 1, which performs heat exchange between the absorption liquid sent from the evaporator to the condenser and the absorption liquid sent from the condenser to the evaporator. Absorption refrigerator with liquid heat exchanger. (3) An absorption refrigerating machine according to claim 1, which includes a vapor heater that heats refrigerant vapor flowing from the regenerator to the condenser using an absorption liquid heated in the regenerator as a heating source, and an absorption refrigerant from the evaporator. An absorption refrigerating machine that has a supercooler that cools the refrigerant vapor flowing into the container using an absorption liquid containing refrigerant flowing from the condenser to the evaporator as a cooling heat source.