JPH01234761A - Double-effect multi-stage pressure type absorption type refrigerator and system therefor - Google Patents

Abstract

PURPOSE:To cool air directly, and to reduce the corrosion of materials by carrying out the manupulation of concentrating an absorbent through a low-temperature regenerator and a condenser under a plurality of different pressures and then by carrying out the manupulation of diluting the absorbent through an absorber and an evaporator under a plurality of different pressures and further by carrying out the manupulation of concentrating the absorbent through a high-temperature regenerator and the low-temperature regenerator under a plurality of different pressures. CONSTITUTION:A diluted absorbent 20 is concentrated at the high pressure part 1a and the low pressure part 1b of a high-temperature regenerator to be sent to the high pressure part 2a of a low-temperature regenerator as an intermediate absorbent 21. Refrigerant vapor 30a is sent to the high pressure part 2a of the low-temperature regenerator and refrigerant vapor 30b to the low pressure part 2b thereof, as respective heating sources. The intermediate absorbent 21 is concentrated at the high pressure part 2a and low pressure part 2b of the low-temperature regenerator to be converted into a rich absorbent 22 and sent to the low pressure part 4b of an absorber. Refrigerant vapor 31a and refrigerant vapor 31b are condensed at the high pressure part 3a and the low pressure part 3b of a condenser, respectively. A refrigerant 31 is sent to the high pressure part 5a and low pressure part 5b of an evaporator together with a refrigerant 30. The rich absorbent 22 absorbs refrigerant vapor 32b at the low pressure part 4b and refrigerant vapor 32a at the high pressure part 4a of the absorber to be diluted. Thus, said rich absorbent 22 is converted into the diluted absorbent 20 to be sent to the high pressure part 1a again after preheated.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a dual-effect absorption refrigeration cycle and its device;
In particular, the present invention relates to a multi-pressure double-effect absorption refrigeration cycle and its device, which are suitable for raising the cooling temperature by keeping the maximum internal pressure below atmospheric pressure.

[Conventional technology]

The basic cycle of conventional dual-effect absorption refrigeration is, for example, as described in JP-A-62-108973, and basically consists of a high temperature regenerator 1. Low temperature regenerator 2° condenser 3. Absorber 4. It consists of seven elements: an evaporator 5 and two heat recovery units 6 and 7, and the five elements are operated under the same pressure inside each vessel. In other words, the dilute absorbent 20 is heated in the high-temperature regenerator 1, the refrigerant 30 is evaporated and concentrated to an intermediate concentration, and after heat exchange in the high-temperature heat recovery device 7 as the intermediate absorbent 21, the low-temperature regeneration is performed at a lower pressure than the high-temperature regenerator. Sent to vessel 2. There, the intermediate absorbent 21 is heated by the refrigerant vapor 30 generated by the high-temperature regenerator 1, generating refrigerant vapor 31, and the intermediate absorbent 21 is concentrated, and after heat exchange in the low-temperature heat recovery device 6 as a concentrated absorbent 22. , and is further sent to the absorber 4 where the internal pressure is low. On the other hand, refrigerant vapor 31 generated in the low-temperature regenerator 2 is cooled and condensed in the condenser 3. In addition, refrigerant vapor 3 generated in the high-temperature regenerator 1
o is used for heating the intermediate absorbent 21 of the low temperature regenerator 2,
The refrigerant vapor 30 is cooled and condensed to become a liquid phase refrigerant 30, which is sent to the evaporator 5 together with the refrigerant 31 from the condenser 3. Since the concentrated absorbent 22 sent to the absorber 4 is cooled there, the water vapor inside the absorber is absorbed by the absorbent and the pressure decreases.

- Since the pressure of the evaporator 5 connected to the force absorber also decreases, the refrigerant 32 (a mixture of refrigerants 30 and 31) circulating by the pump 41 evaporates, and the latent heat of evaporation causes the evaporator 5 to evaporate.
is cooled, and cold water is obtained from the heat transfer tube 50 installed in the vessel. The refrigerant vapor 32 generated in the evaporator 5 is absorbed by the concentrated absorbent 22 in the absorber 4, and the absorbent is diluted to become the diluted absorbent 20. 7 and returned to the high temperature regenerator 1 again. Cooling water 9 that cools the absorber 4 and the condenser 3 and has a raised temperature
is cooled in the cooling tower 8 and used again. Next, a cycle will be explained using a Duhring diagram in FIG. 8, taking water/lithium bromide aqueous solution as an example of a refrigerant/absorbent. The horizontal axis shows temperature and the vertical axis shows water vapor pressure. To explain this in conjunction with FIG.
) heated at a temperature of 154°C and the concentration ranges from 57% to 59.5%
It is concentrated to an intermediate absorbent 21 (■ in the figure). The refrigerant vapor 30 generated there is cooled and condensed in the heat transfer tube 52 of the low temperature regenerator 2 (■). The intermediate absorbent 21 is the internal pressure cuff 5ni.
It is heated with refrigerant vapor 30 in the nHg low temperature regenerator 2 (temperature 94° C.) and concentrated from 59.5% to 62% to become a concentrated absorbent 22 (■). The generated refrigerant vapor 31 is cooled and condensed in the condenser 3 (P=75.T=45) (■)
. Refrigerant 30.3 in low temperature regenerator 2 (■) and condenser 3 (■)
1 is sent to the evaporator 5, where the internal pressure is 6.2 nmHg.
It evaporates at 4°C to obtain a temperature of 4°C (■). - The generated refrigerant vapor 32 is absorbed by the concentrated absorbent 22 in the absorber 4 (■)
.

[Problem to be solved by the invention]

In the conventional dual-effect absorption refrigeration cycle described above, the thermal energy necessary for concentrating the absorbent is supplied only from the high-temperature regenerator 1 and used for concentrating the absorbent.

Since the heat of condensation of the refrigerant vapor 30 generated in the high-temperature regenerator is reused as the heat source for concentrating the absorbent in the low-temperature regenerator 2, the required thermal energy is about half that of the - type operation, resulting in energy savings.

On the other hand, as shown in Figure 8, the heating temperature of the low temperature regenerator is is determined by the high temperature regeneration process power, which results in a cooling temperature of 4°C.
The cooling temperature (■, ■) that caused (■) to occur is determined. Compared to compression refrigeration cycles, absorption refrigeration cycles have the advantage that the operating pressure is below atmospheric pressure (they are not high-pressure vessels), and are required to operate at below atmospheric pressure. Therefore, in order to obtain cold heat of 4°C and operate a dual-effect absorption refrigeration cycle with an internal pressure below atmospheric pressure (pressure of ■, ■), in principle, condenser 3 (■) and absorber 4 The upper limit of the cooling temperature in (■) is limited and is usually 38°C or less.

It is necessary to use low-temperature cooling water 9 using a cooling tower 8 as the cooling source, and since direct cooling with air is difficult, there are problems in terms of equipment cost of the cooling tower and quality control of the cooling water. In addition, in the absorption refrigeration cycle, the thermal energy used to concentrate the absorbent is exhausted as cooling heat for the condenser and absorber, but its low temperature makes it difficult to reuse.

Furthermore, since the absorbent used is generally a concentrated aqueous solution of an inorganic electrolyte, it is highly corrosive to the material, and the corrosivity becomes more severe as the concentration of the absorbent increases and the temperature increases.

In general, a dual-effect absorption refrigeration cycle has a ratio of regeneration concentration of absorbent (60 → 62%) and temperature (94 → 15%) to the type of operation.
4°C), and prevention of material corrosion is a practical issue.

The first object of the present invention is to overcome the drawbacks of the prior art when the maximum internal pressure is below atmospheric pressure. The cooling temperature of the condenser and absorber is increased to enable direct cooling with air (air cooling) and recovery of cooling heat.The second purpose is to lower the heating temperature in the high temperature regenerator as much as possible.

The purpose is to make the material advantageous for corrosion protection.

[Means for solving the problem] The first objective is to achieve below atmospheric pressure by basically concentrating the absorbent in the low-temperature regenerator and condenser under multiple different pressures. Furthermore, the cooling temperature can be further increased by diluting the absorbent in the absorber and evaporator under a plurality of different pressures. The second objective is achieved by performing the absorbent concentration operations in the high-temperature regenerator and the low-temperature regenerator under a plurality of different pressures.

[Effect]

The main points of the present invention will be explained using the solid line in FIG. 2, taking two-stage pressure as an example. First, in order to raise the cooling temperature of the condenser while keeping the maximum internal pressure below atmospheric pressure, the low-temperature regenerator and the condenser are separated into two, and the absorbent is concentrated in two stages (regeneration and condensation). .

Increase the pressure inside the vessel (■→■′). This increases the pressure in the condenser and allows the condensation (cooling) temperature to rise (■→
■′). Next, the cooling temperature of the absorber can be increased by dividing the absorber and evaporator into two parts and diluting the absorbent in two stages (absorption and evaporation) (■→ ■′).

Due to the above actions, the cooling of the dual-effect absorption refrigeration cycle (
condenser and absorber) temperature can be increased. In order to lower the heating temperature required for concentrating the absorbent, the refrigerant condensing sections of the high-temperature regenerator and the low-temperature regenerator are each divided into two parts, and the absorbent is concentrated in two stages (regeneration and condensation). The heating temperature of the vessel decreases (■→■′).

〔Example〕

Hereinafter, one embodiment of the present invention will be described in detail with reference to FIGS. 1 and 2 (the dotted lines in the figures indicate conventional cycles). FIG. 1 shows the basic system of the present invention, which is a double membrane pressure double-effect absorption refrigeration system.

The difference from the conventional system (Fig. 7) is that the high-temperature regenerator has a high-pressure section 1a and a low-pressure section 1b, the low-temperature regenerator has a high-pressure section 2a and a low-pressure section 2b, and the condenser has a high-pressure section 3a and a low-pressure section 3b. The absorber is also divided into a high pressure section 4a and a low pressure section 4b, and the evaporator is also divided into a high pressure section 5a and a low pressure section 5b.

The dilute absorbent 20 enters the high-pressure section 1a of the high-temperature regenerator and is heated and concentrated (■'), and further heated and concentrated in the low-pressure section 1b (■
#) After being cooled in the high-temperature heat recovery device 7 as the intermediate absorbent 21, it is sent to the high-pressure section 2a of the low-temperature regenerator. Refrigerant vapor 30a generated in the high pressure section 1a of the high temperature regenerator is sent as a heat source for the high pressure section 2a of the low temperature regenerator, and refrigerant vapor 30b generated in the low pressure section 1b is sent as a heat source for the low pressure section 2b of the low temperature regenerator. The intermediate absorbent 21 is heated and concentrated in the high pressure section 2a of the low-temperature regenerator (■'), and further heated and concentrated in the low pressure section 2b (■#) to become a concentrated absorbent 22.

After being cooled in the low-temperature heat recovery device 6, it is sent to the low-pressure section 4b of the absorber. Refrigerant vapors 31a and 31b generated in the high-pressure section 2a and low-pressure section 2b of the low-temperature regenerator are sent to the high-pressure section 3a (■') and low-pressure section 3b (■) of the condenser, respectively, where they are cooled and condensed. The refrigerant 31 condensed there is sent to the evaporator together with the refrigerant 30 condensed on the heating side of the low temperature regenerator, and pump 41
From there, it is circulated to the high pressure section 5a and low pressure section 5b of the evaporator.

On the other hand, the concentrated absorbent 22 is diluted (■') in the low pressure section 4b of the absorber by absorbing the refrigerant vapor 32b generated (■) in the evaporator low pressure section 5b, and is further sent to the high pressure section 4a, where the evaporator high pressure The refrigerant vapor 32a generated (■') in the section 5a is absorbed and diluted to become a dilute absorbent 20. After the dilute absorbent 20 is preheated by the pump 40 in the low-temperature heat recovery device 6 and the high-temperature heat recovery device 7, it is sent again to the high-pressure section 1a of the high-temperature regenerator.

Although the present invention has been described above using a two-stage pressure system, it is not limited to two stages. Further, although the present invention has been explained using an absorption refrigeration cycle, it can be directly applied to an absorption heat pump cycle based on the same principle.

Next, a water vapor pressure diagram showing another embodiment in which the effects of the present invention are significantly improved is shown in FIG. 3 (the dotted line in the figure indicates the conventional cycle). In order to keep the maximum internal pressure below atmospheric pressure and further raise the cooling temperature, the effect will be increased if each element is subjected to different pressures (multi-stage pressure) and an absorbent with a large pressure gradient with respect to temperature is used.

As absorbents with large pressure gradients, lithium bromide-calcium chloride 2-mix system, lithium bromide-calcium chloride-magnesium chloride 3-mix system, lithium chloride-calcium chloride 2-mix system, lithium chloride-calcium chloride-magnesium chloride 3-mix system There are halogenated substances such as lithium, calcium, and magnesium, such as aqueous solutions of As shown in Figure 3, a mixed absorbent with a high pressure gradient (CaCQ2/MgCQz/LiCQ
= 11/3/1) to generate cold heat of 4°C, the cooling temperature increases by 6°C to 45°C (■'→■～, ■→■'', ■→■'''), and the high temperature regenerator heating temperature is 147℃ (■
→■') and can be lowered by 7℃.

FIG. 4 shows an embodiment of an absorption air conditioner capable of simultaneously generating cooling and heating according to the present invention. The cold water 100 from the evaporator 5 of the absorption refrigerator main body is used as a cooling source for the cold air generator 110 to generate cold air 120, and at the same time, the condenser 3. The high temperature cooling water 200 generated from the absorber 4 is used as a heating source for the hot air generator 210 to generate hot air 220. Further, in this embodiment, an imbalance between cold/heat demand is prevented by installing a heat storage tank 300. Additionally, a cold/heat storage tank may be installed to prevent imbalance.

FIG. 5 shows another embodiment of a system that supplies heat in a concentrated manner to a building or area using the present invention. Heat supply generally includes air conditioning as cold energy, heating and hot water supply as hot energy, and hot water supply is 50~
80°C is required. In this embodiment, heating and cooling are performed in the same manner as shown in FIG. 4, and another heat pump (for example, a compression heat pump) 500 is also combined.

That is, a part of the high temperature cooling water (approximately 40°C) 200 of the absorber 4 and condenser 3 is used as a heat source for the evaporator 510 of the compression heat pump, and is heat pumped through the compressor 530.
A higher temperature (50 to 80°C) is generated from the condenser 520 and sent to the heating source of the hot water supply 600 and the hot air generator 210.
Used for rapid heating at startup.

FIG. 6 shows an embodiment of an air-cooled dual-effect absorption refrigerator according to the present invention. A fan 710 sends air 700 directly to the absorber 4 and condenser 3 for cooling. The outside air temperature is around 30℃ in summer, and considering the heat exchange capacity of the absorber and condenser, the air flow rate, etc., the minimum temperature of the absorber or condenser is 38℃ to keep the cold generation temperature below 7℃. Above that, it becomes an absorber.

As the condenser becomes larger, the amount of air blown also increases, which is not practical.If the absorber, low-temperature regenerator, etc. are set to multi-stage pressure as in the present invention, the minimum temperature can be increased to 38°C or higher (43°C in Figure 2). , 45°C in Figure 3).

In this embodiment, the absorber and condenser for cooling water are connected in series, but depending on the application, the water may be fed in the reverse direction, in parallel, or individually.

[Effects of the Invention] According to the present invention, by raising the cooling temperature of the dual-effect absorption refrigeration cycle while keeping the maximum internal pressure below atmospheric pressure,
In the example shown in Fig. 2, 39°C to 43°C). By enabling direct air cooling, a cooling tower is not required, reducing equipment costs and making it possible to reuse cooling heat. Therefore, the energy saving effect is large. Also, since the regeneration temperature of the absorbent can be lowered (from 154°C to 150°C in the example shown in Figure 2),
It has the effect of reducing material corrosion caused by the absorbent.

[Brief explanation of the drawing]

Fig. 1 shows a two-stage pressure dual-effect absorption refrigeration system which is a basic embodiment of the present invention, Fig. 2 shows a water vapor pressure diagram explaining the refrigeration cycle shown in Fig. 1, and Fig. 3 shows a large pressure gradient. Water vapor pressure diagram showing another embodiment of the present invention using an absorbent, No. 4
The figure shows another embodiment of the present invention capable of generating hot and cold heat, FIG. 5 shows another embodiment of the present invention combined with another heat pump, and FIG. 6 shows another embodiment of the present invention capable of air cooling. For example, Fig. 7 is a conventional dual-effect absorption refrigeration system, and Fig. 8 is a water vapor pressure diagram explaining the current cycle. 1a... High temperature regenerator high pressure section, 1b... High temperature regenerator low pressure section, 2a... Low temperature regenerator high pressure section, 2b... Low temperature regenerator low pressure section, 3a... Condenser high pressure section, 3b ...Condenser low pressure section, 4a...Absorber high pressure section, 4b...Absorber low pressure section, 1st port Z section temperature ['C] 3rd passage [・C] 5th section 6θ0 Chaotsu-ku No. 7 rfJ Kusa 8 mouth=h/a ['c]

Claims (1)

[Claims] 1. In a dual-effect absorption refrigerator comprising a high-temperature regenerator, a low-temperature regenerator, a condenser, an evaporator, and an absorber, the low-temperature regenerator and the condenser are connected to a plurality of different pressure chambers. A dual-effect multi-stage pressure absorption chiller characterized by separate parts. 2. A dual-effect multi-stage pressure absorption refrigerator according to claim 1, characterized in that the high-temperature regenerator, evaporator, and absorber are separated into a plurality of different pressure chambers. Pressure absorption refrigerator. 3. A high-temperature regenerator that heats the dilute absorbent to evaporate the refrigerant and concentrate it to an intermediate concentration; the refrigerant vapor generated in the high-temperature regenerator heats the intermediate-concentration absorbent to generate a high-concentration absorbent and refrigerant vapor. A condenser that is maintained at the same internal pressure as the low-temperature regenerator and condenses the refrigerant vapor generated in the low-temperature regenerator, an evaporator that evaporates the condensate generated in the condenser, and an evaporator that is the same as the evaporator. A double-effect absorber that is maintained at an internal pressure and absorbs refrigerant vapor generated in the evaporator into the high-concentration absorbent, and a means for supplying the dilute absorbent generated in the absorber to the high-temperature regenerator. 1. A dual-effect multi-pressure absorption refrigerating machine, characterized in that the low temperature regenerator and the condenser are separated into a plurality of different pressure chambers. 4. A dual-effect multi-stage pressure absorption refrigerator according to claim 3, characterized in that the high-temperature regenerator, evaporator, and absorber are separated into a plurality of different pressure chambers. Pressure absorption refrigerator. 5. A high-temperature regenerator that heats the dilute absorbent to evaporate the refrigerant and concentrate it to an intermediate concentration; the refrigerant vapor generated in the high-temperature regenerator is separated into a plurality of different pressure chambers, and heats the intermediate-concentration absorbent to achieve a high concentration. a low-temperature regenerator that generates absorbent and refrigerant vapor; a condenser that is formed in a plurality of different pressure chambers and condenses the refrigerant vapor generated in the low-temperature regenerator; and an evaporator that evaporates the condensed liquid generated in the condenser. An absorber that is maintained at the same internal pressure as the evaporator and absorbs refrigerant vapor generated in the evaporator into the high-concentration absorbent, and means for supplying the dilute absorbent generated in the absorber to the high-temperature regenerator. A dual-effect multi-stage pressure absorption chiller characterized by: 6. The dual-effect multi-stage pressure absorption refrigerator according to claim 5, characterized in that the high-temperature regenerator, evaporator, and absorber are separated into a plurality of different pressure chambers. Pressure absorption refrigerator. 7. High-temperature regeneration step in which the dilute absorbent is heated to evaporate the refrigerant and concentrated to an intermediate concentration; the intermediate-concentration absorbent is heated with the refrigerant vapor generated in the high-temperature regeneration step to generate high-concentration absorbent and refrigerant vapor. a low-temperature regeneration step in which the refrigerant vapor generated in the low-temperature regeneration step is condensed, an evaporation step in which the condensate generated in the condensation step is evaporated, and the refrigerant vapor generated in the evaporation step is absorbed into the high concentration absorbent. and a dilute absorbent supply step in which the dilute absorbent generated in the absorption step is supplied to the high temperature regeneration step, and the concentration step of the intermediate concentration absorbent in the low temperature regeneration step and the condensation step is performed in a plurality of different ways. A dual-effect, multi-stage pressure absorption chiller system that operates under internal pressure. 8. The dual-effect multi-pressure absorption refrigeration system according to claim 7, characterized in that the high temperature regeneration step, evaporation step and absorption step are performed under a plurality of different internal pressures. Heavy-effect multi-pressure absorption refrigeration system. 9. A dual-effect multi-stage pressure absorption refrigerating machine according to claim 3, characterized in that an absorbent having a large pressure gradient with respect to temperature is used as an absorbent. . 10. A dual-effect multi-stage pressure absorption refrigerating machine system according to claim 7, characterized in that an absorbent having a large pressure gradient with respect to temperature is used as the absorbent. machine system. 11. High-temperature regeneration step in which the dilute absorbent is heated to evaporate the refrigerant and concentrated to an intermediate concentration; the intermediate-concentration absorbent is heated with the refrigerant vapor generated in the high-temperature regeneration step to generate high-concentration absorbent and refrigerant vapor. a condensation step to condense the refrigerant vapor generated in the low-temperature regeneration step, an evaporation step to evaporate the condensate generated in the condensation step, and a refrigerant vapor generated in the evaporation step to the high concentration absorbent. It consists of an absorption step of absorbing and a dilute absorbent supply step of supplying the dilute absorbent generated in the absorption step to the high temperature regeneration step, and a plurality of steps of concentrating the intermediate concentration absorbent in the low temperature regeneration step and the condensation step. A heat generation type absorption refrigeration system, characterized in that heat generation is performed under different internal pressures and heat is recovered from at least one of the condensation step and the absorption step. 12. High-temperature regeneration step in which the dilute absorbent is heated to evaporate the refrigerant and concentrated to an intermediate concentration; the intermediate-concentration absorbent is heated with the refrigerant vapor generated in the high-temperature regeneration step to generate high-concentration absorbent and refrigerant vapor. a condensation step to condense the refrigerant vapor generated in the low-temperature regeneration step, an evaporation step to evaporate the condensate generated in the condensation step, and a refrigerant vapor generated in the evaporation step to the high concentration absorbent. It consists of an absorption step in which the absorbent is absorbed and a dilute absorbent supply step in which the dilute absorbent generated in the absorption step is supplied to the high temperature regeneration step, and the concentration step of the intermediate concentration absorbent in the low temperature regeneration step and the condensation step is A heat generation type absorption refrigeration system, characterized in that the heating is carried out under internal pressure, cold heat is recovered in the evaporation process, and warm heat is recovered from at least one of the condensation process and the absorption process. 13. High-temperature regeneration step in which the dilute absorbent is heated to evaporate the refrigerant and concentrated to an intermediate concentration; the intermediate-concentration absorbent is heated with the refrigerant vapor generated in the high-temperature regeneration step to generate high-concentration absorbent and refrigerant vapor. a condensation step to condense the refrigerant vapor generated in the low-temperature regeneration step, an evaporation step to evaporate the condensate generated in the condensation step, and a refrigerant vapor generated in the evaporation step to the high concentration absorbent. It consists of an absorption step of absorbing and a dilute absorbent supply step of supplying the dilute absorbent generated in the absorption step to the high temperature regeneration step, and a plurality of steps of concentrating the intermediate concentration absorbent in the low temperature regeneration step and the condensation step. A heat generating absorption refrigeration system characterized in that the evaporation step is performed under different internal pressures, the minimum temperature of the evaporation step is 7° C. or lower, and the minimum temperature of the absorption step and the condensation step is 38° C. or higher.