JPH06300382A - Double effect absorption type refrigerating machine - Google Patents

Abstract

PURPOSE:To enhance a rise characteristic at the time of restarting of an operation by a method wherein an inhibitor is made to spread over the whole at the time of restarting of the operation, production of a non-condensible gas is suppressed effectively, the number of times of supplement of the inhibitor is lessened and also the time for a diluting operation is shortened. CONSTITUTION:A double effect absorption type refrigerating machine equipped with a high-temperature regenerator 2, a lowtemperature regenerator 4, a condenser 5, an evaporator 6, an absorber 7, a low-temperature heat exchanger 8 and a hightemperature heat exchanger 9 and using a water solution of an absorbent and water as a refrigerant. A supply passage l for supplying the liquid refrigerant in the evaporator 6 into a flow passage of the water solution of the absorbent of high concentration of the low-temperature heat exchanger 8 is provided. A solenoid operated valve 22 is provided for the supply passage 21.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a double-effect absorption refrigeration system in which a vacuum is formed inside and a lithium bromide aqueous solution containing, for example, water as a refrigerant and lithium bromide as an absorbent is enclosed. Regarding the machine.

[0002]

As a double-effect absorption refrigerator of this kind, conventionally, a high temperature regenerator, a low temperature regenerator, a condenser, an evaporator, an absorber, a low temperature heat exchanger, a high temperature heat exchanger, and a lithium bromide aqueous solution have been used. Equipped with a solution pump that sends from the absorber to the high temperature generator and a refrigerant circulation pump that sprays the water in the evaporator to the heat transfer tubes of the evaporator again, it is widely known that it is used in a completely sealed vacuum state. .

[0003]

In the above double-effect absorption refrigerator, the aqueous solution of lithium bromide has a high concentration (63 to 64 wt%) and a high temperature (150 to 1) during cold water production.
70 ° C) in some cases. Then, as the concentration and temperature of the aqueous lithium bromide solution become higher, a non-condensable gas is more likely to be generated due to a chemical reaction with the metal, and the generated non-condensable gas is the heat transfer tube in the body of the absorber having the lowest pressure. There is a problem in that the absorption action is weakened by gathering around, and the capacity of the absorption refrigerator is significantly reduced. The generation of the non-condensable gas is remarkable especially in the high temperature regenerator.

Therefore, in order to suppress the generation of the non-condensable gas, an inhibitor such as molybdic acid type, chromic acid type or nitric acid type is added to the aqueous solution of lithium bromide, and the action of the inhibitor makes the metal surface stable and uniform. An oxide film is formed to suppress the generation of non-condensable gas. By the way, the inhibitor is gradually consumed during the operation of the absorption chiller due to the formation of an oxide film, and the amount thereof becomes insufficient, so the lithium bromide solution was analyzed and the inhibitor amount was confirmed, and the inhibitor was consumed. Need to replenish the minutes. In addition, since an oxide film is formed on the inner surface of the absorption refrigerator during the initial operation, a large amount of the inhibitor is consumed, so that an excessive amount of the inhibitor is added before the operation is started.

However, the solubility of the inhibitor in a high-concentration aqueous solution of lithium bromide is more affected by the concentration of the aqueous solution of lithium bromide than by temperature and alkalinity. When the concentration of the aqueous solution of lithium bromide is high, the solubility of the inhibitor is high. Is reduced. In the case of a general absorption refrigerator, the concentration of the aqueous lithium bromide solution during cold water production is 56 to 57 wt% in the thinnest case and 62 to 63 wt% in the thickest case.
% Of the added inhibitor is crystallized and precipitated in the high-concentration aqueous solution channel of the low-temperature heat exchanger where the concentration of the lithium bromide aqueous solution is high and the flow rate is slow. As a result, even though the total amount of inhibitor added is excessive, the amount circulating with the aqueous lithium bromide solution is small, especially because the inhibitor does not flow to the most needed high temperature regenerator, There is a problem that the effect of the inhibitor cannot be sufficiently obtained. Moreover, even if a large amount is replenished, there is no effect. In addition, crystallized crystals may precipitate and pitting corrosion may occur.

Further, the excess inhibitor added is
After stopping the operation of the heating source of the high temperature regenerator of the double-effect absorption refrigerator, or when the temperature of the produced cold water dropped below a predetermined temperature, the operation of the heating source of the high temperature regenerator automatically stopped. When the temperature of the post-lithium bromide aqueous solution decreases, crystallization and precipitation occur in a portion where the concentration of the lithium bromide aqueous solution is high. Therefore, in order to prevent this, after the operation of the heating source of the high temperature regenerator is stopped, the aqueous solution pump and the refrigerant circulation pump are continuously operated to perform the dilution operation to reduce the concentration of the lithium bromide aqueous solution. . During such a dilution operation, the inhibitor crystals that have crystallized and precipitated in the high-concentration aqueous solution flow path of the low-temperature heat exchanger are also dissolved, but at the dilution operation concentration (53 to 55 wt%), they are efficiently dissolved. Since it is impossible to do so, there is a problem that the inhibitor dissolved in the lithium bromide aqueous solution is insufficient despite the excessive addition, and the inhibitor needs to be added again, which is a troublesome work.

Moreover, when the above-described dilution operation is performed, it takes time to increase the concentration of the lithium bromide aqueous solution to a predetermined concentration when the operation is restarted, and the start-up characteristic is deteriorated.
Therefore, recently, there has been a tendency to shorten the dilution operation time before the operation is stopped in order to improve the start-up characteristics of the absorption refrigerator, and it becomes more difficult to dissolve the crystallized inhibitor due to the long stop time at high concentration. At the same time, when the outside air temperature is low, the high-concentration aqueous solution may crystallize during the stop, and operation may not be possible.

The object of the present invention is to solve the above problems.
It is to provide a heavy-duty chiller / heater.

[0009]

A double-effect absorption refrigerator according to the present invention comprises a high temperature regenerator, a low temperature regenerator, a condenser, an evaporator, an absorber, a low temperature heat exchanger and a high temperature heat exchanger. In addition, in a double-effect absorption refrigerating machine using an aqueous solution of an absorbent and water as a refrigerant, the liquid refrigerant in the evaporator or the low-concentration absorbent solution in the absorber is mixed with the high-concentration of the low-temperature heat exchanger. A supply path is provided for supplying the absorbent aqueous solution into the flow path, and a valve is provided in the supply path.

[0010]

[Function] The concentration of the absorbent in the flow path of the high-concentration absorbent aqueous solution of the low temperature heat exchanger in which the supersaturated inhibitor is precipitated gradually decreases during the dilution operation, but at the end of the operation, It stops when the concentration is about 53 to 55 wt%.

A supply passage for supplying the liquid refrigerant in the evaporator or the low-concentration absorbent aqueous solution in the absorber into the flow passage of the high-concentration absorbent aqueous solution in the low-temperature heat exchanger is provided, and a valve is provided in this supply passage. If provided, it is possible to open the valve during the dilution operation or after the completion of the dilution operation to supply the liquid refrigerant or the low-concentration absorbent aqueous solution into the high-concentration absorbent aqueous solution flow path of the low-temperature heat exchanger through the supply passage. it can. Therefore, the concentration of the absorbent in the aqueous solution of the high-concentration absorbent aqueous solution of the low-temperature heat exchanger is lowered, and the precipitated inhibitor crystals are dissolved.

[0012]

Embodiments of the present invention will be described in detail below with reference to the drawings. In this example, the double effect absorption refrigerator is a double effect absorption chiller-heater. Throughout the drawings, the same parts and parts are designated by the same reference numerals, and description thereof will be omitted.

FIG. 1 is a schematic configuration diagram of a double-effect absorption chiller-heater according to an embodiment of the present invention.

In FIG. 1, the double-effect absorption chiller / heater is
Using a lithium bromide aqueous solution of water as a refrigerant and lithium bromide as an absorbent, a heating burner (1)
High-temperature regenerator (2) that heats the low-concentration lithium bromide aqueous solution (low-concentration absorbent aqueous solution), and the high-temperature medium-concentration lithium bromide aqueous solution and steam (gas refrigerant) sent from the high-temperature regenerator (2) Separator (3) for separating and the medium-concentration lithium bromide aqueous solution sent from the separator (3) is heated by steam also sent from the separator (3) to obtain a high-concentration lithium bromide aqueous solution ( Water (liquid refrigerant) obtained from the low-temperature regenerator (4) for obtaining high-concentration absorbent solution), the condenser (5) for cooling and condensing the steam that has passed through the low-temperature regenerator (4), and the condenser (5) ) Is evaporated and the water vapor generated in the evaporator (6) is absorbed by the high-concentration lithium bromide aqueous solution sent from the low-temperature regenerator (4) and diluted to dilute the low-concentration lithium bromide aqueous solution. Get the absorber (7), high temperature regenerator from the absorber (7)
A low-temperature heat exchanger (8) for exchanging heat between the low-concentration lithium bromide aqueous solution sent to (2) and the high-concentration lithium bromide aqueous solution sent to the absorber (7) from the low-temperature regenerator (4), and a low temperature High-temperature heat exchanger (9) that exchanges heat between the low-concentration lithium bromide aqueous solution that has passed through the heat exchanger (8) and the medium-concentration lithium bromide aqueous solution that is sent from the separator (3) to the low-temperature regenerator (4). Is equipped with.

The low temperature regenerator (4) and the condenser (5) are provided together in one cylinder via a partition. Low Temperature Regenerator (4)
Is equipped with a heater (11) inside the body, and the steam obtained in the separator (3) is sent to one end of this heater (11),
The steam that has passed through the inside of the (11) is sent to the inside of the condenser (5). The condenser (5) has a cooling water flow pipe (12) in the body, and the cooling water flowing in the cooling water flow pipe (12) causes steam generated in the low temperature regenerator (4) and a heater.
The steam sent from (11) is cooled and condensed and liquefied.

The evaporator (6) and the absorber (7) are integrally provided in one cylinder through a partition. Evaporator (6)
Is equipped with a water sprinkler (13) and a water distribution pipe (14) (heat transfer pipe) inside the body. Then, the water sent from the condenser (5) is sprayed on the water distribution pipe (14) by the water spraying device (13). The sprayed water removes heat of vaporization from the water flowing in the water distribution pipe (14) and evaporates to cool the water, thereby producing cold water. The manufactured cold water is used for cooling. Also the evaporator
In (6), the water that has flowed down without evaporating and accumulated at the bottom is
From the lower end of the evaporator (6), the water circulation pump (15) sends the water to the water sprinkler (13) again via the water circulation pipe (16).

The absorber (7) is provided with a water sprinkler (17) and a cooling water flow pipe (18) inside the body. Then, the high-concentration lithium bromide aqueous solution sent from the low-temperature regenerator (4) was sprayed with the sprinkler (1
7) Sprays on the cooling water flow pipe (18) to form a liquid film on its surface, absorbs water vapor while cooling this liquid film with the cooling water flowing in the flow pipe (18), and produces a low concentration odor. It is designed to obtain a lithium fluoride aqueous solution. The low-concentration lithium bromide aqueous solution thus obtained was absorbed by the aqueous solution circulation pump (19).
It is sent from (7) to the high temperature regenerator (2) via the low temperature heat exchanger (8) and the high temperature heat exchanger (9). Then low temperature regenerator (4)
To the absorber (7) through the low temperature heat exchanger (8). The cooling water that has passed through the cooling water flow pipe (18) is sent to the cooling water flow pipe (12) of the condenser (5).

Further, between the separator (3) and the evaporator (6),
A pipe (10) for supplying the lithium bromide aqueous solution in the separator (3) to the evaporator (6) is provided, and a valve (20) is provided in the middle of this pipe (10).
Is provided. During hot water production, the valve (20) is opened, and the hot lithium bromide aqueous solution heated by the heating burner (1) in the high temperature regenerator (2) and sent to the separator (3) is evaporated. The water sent to (6) and flowing in the water flow pipe (14) is heated to produce hot water.
Since there is no step of concentrating the aqueous solution of lithium bromide during hot water production, its concentration is lower than during cold water production (51-51).
52 wt%), and the concentration is uniform throughout. Therefore, the crystals of the excessively added inhibitor generated during the production of cold water are dissolved, the amount of the inhibitor in the circulating lithium bromide aqueous solution increases, and replenishment becomes unnecessary.

The structure and operation of the double-effect absorption chiller-heater up to this point are known, and detailed description thereof will be omitted.

Between the portion of the water circulation pipe (16) on the discharge side of the water circulation pump (15) and the low temperature heat exchanger (8), an evaporator (6)
A supply path (21) is provided for supplying water in the high-concentration lithium bromide aqueous solution flow path of the low temperature heat exchanger (8). Supply path (2
A solenoid valve (22) is provided in the middle of 1).

In the above, the water flow pipe (1
When the temperature of the water passing through 4) drops and reaches the specified temperature,
Or when the shutdown switch is operated, the high temperature regenerator
The heating burner (1) of (2) is stopped. Burner (1)
After the suspension, the dilution operation is performed, the water circulation pump (15) and the aqueous solution circulation pump (19) continue to operate, and the lithium bromide aqueous solution absorbs water vapor in the absorber (7), whereby the aqueous solution concentration gradually decreases. Then, after the elapse of a predetermined set time or when the temperature of the high temperature regenerator (1) drops to the predetermined set temperature, only the aqueous solution circulation pump (19) is stopped. At the same time, the solenoid valve (22) opens. Then, the water circulation pump (1
Water is sent into the high-concentration aqueous solution channel of the low-temperature heat exchanger (8) by 5), and the concentration of the aqueous solution in this channel is about 20-30.
It can be reduced to wt%. As a result, low temperature heat exchanger (8)
Due to the decrease in the concentration of the aqueous solution in the high-concentration aqueous solution channel, the excess inhibitor crystallized in this channel is
Dissolves in a short time. Then, the water circulation pump (15) is stopped and the solenoid valve (22) is closed. The operation of the water circulation pump (15) and the transition of the solenoid valve (22) from the open state to the closed state are
The time is set by the timer.

The operation signal is input again, the low concentration aqueous solution in the regenerator (2) is heated by the burner (1), and the aqueous solution circulation pump (19) and the water circulation pump (15) are activated,
When the aqueous solution of lithium bromide begins to flow, the inhibitor dissolved in the low temperature heat exchanger (8) is sent to the absorber (7) and passes through the low temperature heat exchanger (8) and the high temperature heat exchanger (9). Since it is sent to the high temperature regenerator (1), the excess inhibitor is effectively used as a whole and the generation of non-condensable gas is effectively suppressed. Therefore, by supplying the excess inhibitor, the number of times of supplementing the inhibitor can be reduced and the number of times of maintenance can be reduced.

2 to 4 show a second embodiment of the present invention.

2 to 4, a pipe (2) for connecting the absorber (7) and the low temperature heat exchanger (8) to each other is provided in the middle of the supply path (21).
Pilot type on-off valve (2) that opens and closes using the pressure on the discharge side of the aqueous solution circulation pump (19) in 3) as pilot pressure
4) is provided. The supply path (21) includes a first conduit (21a) connecting the water circulation pipe (16) and the valve box (25) of the on-off valve (24),
It is provided with a valve box (25) and a second conduit (21b) connecting the high-concentration aqueous solution flow path of the low temperature heat exchanger (8). The on-off valve (2
In the valve box (25) of 4), the branch pipe (23
a) is connected. A valve seat (26) is provided at the connection end of the second conduit (21b) to the valve box (25). Branch pipe (23a)
A bellows (27), which is normally in a contracted state, is attached to the connection end of the valve box (25) of the valve seat (26) at the tip of the bellows (27).
A valve element (28) that is pressed against is attached.

Refrigerant circulation pump (15) and aqueous solution circulation pump (1
The pump head difference of 9) is about 1.0 kg / m ² G, and when both pumps (15) and (19) are operating, as shown in FIG. Piping for connecting the exchanger (8)
The bellows (27) expands using the pressure on the discharge side of the aqueous solution circulation pump (19) in (23) as the pilot pressure, and the valve body (2
8) is brought into pressure contact with the valve seat (26) to close the on-off valve (24), and water is prevented from flowing into the second conduit (21b).

When only the aqueous solution circulation pump (19) is stopped after the completion of the dilution operation, the bellows (27) contracts and the valve body (28) separates from the valve seat (26) as shown in FIG. (24) opens. As a result, water flows into the low-temperature heat exchanger (8) through the second conduit (21b), and the high-concentration aqueous solution flow path of the low-temperature heat exchanger (8) is processed in the same manner as in the embodiment shown in FIG. The excess inhibitor that had crystallized inside dissolves.

FIGS. 5 and 6 show an aqueous solution circulation pump in the pipe (23) for connecting the absorber (7) and the low temperature heat exchanger (8).
A modification of the pilot-type on-off valve that opens and closes by using the pressure on the discharge side of (19) as the pilot pressure is shown.

5 and 6, a valve seat (32) is provided at the connection end of the second conduit (21b) to the valve box (31) of the on-off valve (30), and the valve box (31) is provided. A first valve body (33), which is in pressure contact with the valve seat (32), is provided therein. Also, the first conduit
A valve seat (34) is provided at the connection end of (21a) to the valve box (31), and a second valve body (35) that is in pressure contact with this valve seat (34) is provided in the valve box (31). It is provided. The first valve body (33) is a guide member provided in the second conduit (21b) and the branch pipe (23a).
Guide rods (38) (39) provided on the valve body (33) by (36) (37)
Is guided to move.
The first valve body (33) is biased toward the branch pipe (23a) by the tension coil spring (41). The second valve body (35) is
It is urged toward the first conduit (21a) side by the tension coil spring (42).

In such a structure, both pumps (15) (1
When 9) is activated, as shown in Fig. 5, the absorber
The first valve element (33) has the valve seat (32) with the pressure at the discharge side of the aqueous solution circulation pump (19) in the pipe (23) connecting the low temperature heat exchanger (8) and the low temperature heat exchanger (8) as pilot pressure. And the second valve element (35) is pressed against the valve seat (34) by the above pressure to close the on-off valve (30), and the second conduit (21
Inflow to b) is blocked.

When only the aqueous solution circulation pump (19) is stopped after the dilution operation is completed, as shown in FIG.
(41) separates the first valve body (33) from the valve seat (32), and the water pressure causes the second valve body (35) to separate from the valve seat (34) and open the on-off valve (30). . As a result, the water is in the second conduit (21b)
After flowing into the low temperature heat exchanger (8), the excess inhibitor crystallized in the high-concentration aqueous solution channel of the low temperature heat exchanger (8) is dissolved in the same manner as in the embodiment shown in FIG.

FIG. 7 shows still another embodiment of the present invention.

In FIG. 7, an absorber (7) and a low temperature heat exchanger are shown.
The low temperature heat exchanger and the discharge side part of the aqueous solution circulation pump (19) in the pipe (23) communicating the low concentration aqueous solution flow path of (8)
Provided between the high-concentration aqueous solution flow path of (8) and the high-concentration aqueous solution flow path of the low-temperature heat exchanger (8) is a supply path (45) for supplying the low-concentration aqueous solution obtained in the absorber (7). Has been. A solenoid valve (46) is provided in the middle of the supply path (45).

When the solenoid valve (46) is opened during the dilution operation, the aqueous solution circulation pump (19) causes the low-concentration lithium bromide aqueous solution in the absorber (7) to flow in the high-concentration aqueous solution flow path of the low temperature heat exchanger (8). And the concentration of the aqueous solution in this channel is reduced. As a result, the concentration of the aqueous solution in the high-concentration aqueous solution channel of the low-temperature heat exchanger (8) is lowered, and the excess inhibitor crystallized in this channel is dissolved.

In all of the above embodiments, the present invention is applied to an absorption chiller-heater, but the present invention is not limited to this, and can be applied to a chiller exclusively for producing chilled water.

[0035]

According to the double-effect absorption refrigerator of the present invention, as described above, the concentration of the absorbent in the aqueous solution of the high-absorbent-containing aqueous solution of the low temperature heat exchanger decreases, and The inhibitor crystals that had settled inside dissolve. Therefore, when the operation is restarted, the inhibitor is spread over the entire area, and the generation of the non-condensable gas can be effectively suppressed. In addition, it is possible to prevent pitting corrosion due to precipitated crystals. Also,
Inhibitors are replenished less frequently and maintenance becomes easier. Further, regardless of the length of the dilution operation time, the inhibitor crystals precipitated in the high-concentration absorbent aqueous solution flow path of the low-temperature heat exchanger can be dissolved, so that the dilution operation time can be shortened. By thinning the high-concentration aqueous solution, it is possible to prevent crystal troubles of the aqueous solution due to a decrease in outside air temperature. Therefore, it is possible to improve the start-up characteristic when the operation is restarted.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing an embodiment of the present invention.

FIG. 2 is a schematic configuration diagram showing another embodiment of the present invention.

FIG. 3 is an enlarged view showing a portion of an opening / closing valve of FIG.

FIG. 4 is a view corresponding to FIG. 3 showing a state different from FIG.

5 is a view corresponding to FIG. 3 showing a modified example of the on-off valve of the double-effect absorption chiller / heater shown in FIG. 2.

FIG. 6 is a view equivalent to FIG.

FIG. 7 is a schematic configuration diagram showing still another embodiment of the present invention.

[Explanation of symbols]

 2 High temperature regenerator 4 Low temperature regenerator 5 Condenser 6 Evaporator 7 Absorber 8 Low temperature heat exchanger 9 High temperature heat exchanger 21 Supply path 22 Solenoid valve 24 Open / close valve 30 Open / close valve 45 Supply path 46 Solenoid valve

Claims (1)

[Claims] 1. A high temperature regenerator, a low temperature regenerator, a condenser, an evaporator, an absorber, a low temperature heat exchanger and a high temperature heat exchanger are provided, and an aqueous solution of an absorbent and water as a refrigerant is used. In the double-effect absorption refrigerator, a supply passage is provided for supplying the liquid refrigerant in the evaporator or the low-concentration absorbent aqueous solution in the absorber into the high-concentration absorbent aqueous solution flow passage in the low-temperature heat exchanger, A double-effect absorption refrigerator with a valve provided in this supply path.