JPH0563707B2 - - Google Patents

Description

[Detailed Description of the Invention] (a) Field of Industrial Application The present invention relates to an absorption refrigeration machine that is used for taking out cold water for cooling, making ice, or for heat pumps, etc. using an absorption refrigeration cycle, and particularly relates to an absorption refrigeration machine that uses a rectifier and a demultiplexer. The present invention relates to an absorption refrigerator equipped with an absorption refrigerator.

(b) Prior art In absorption refrigerators in which the combination of refrigerant and absorbent is organic such as Freon 22-tetraethylene glycol dimethyl ether, trifluoroethanol-N-methyl 2-pyrrolidone, or water-ammonia. In this case, absorbent gas is mixed into the refrigerant gas generated by the generator. Furthermore, if this refrigerant gas is liquefied as it is and supplied to the evaporator, the absorption refrigerating machine will not be able to fully demonstrate its performance because the refrigerant has low purity.

Therefore, as seen in Japanese Patent Application Laid-Open No. 58-221357, absorption refrigeration is a conventional technique for increasing the purity of refrigerant, in which a rectifier and a demultiplexer are installed between a generator and a condenser. (hereinafter referred to as this type of absorption refrigerator).

(c) Problems to be solved by the invention In the conventional absorption refrigerator of this type as described above, compared to an absorption refrigerator which is not equipped with a rectifier or a decentralizer, it is difficult to use a high-purity refrigerant in the evaporator. However, if the heat exchange between the refrigerant gas and the cooling fluid of this gas in the dephlegmator is inadequate, the amount of refrigerant liquefied in the dephlegmator that is returned to the rectifier may be insufficient. , become excessive. If the reflux amount is insufficient, the rectification efficiency of the rectifier will decrease, making it impossible to maintain high purity of the refrigerant, resulting in a decrease in the performance of the absorption refrigerator.Furthermore, if the reflux amount is excessive, the evaporator There is a problem in that the amount of refrigerant flowing to the side is insufficient, causing a decline in the performance of the absorption refrigerator.

In view of this problem, the present invention aims to improve the performance of this type of absorption refrigerator by adjusting the amount of refrigerant recirculated from the dephlegmator to the rectifier to almost the optimum value. It is.

(d) Means for Solving the Problems The present invention solves the problems by improving the difference between the inflow temperature of the refrigerant into the demultiplexer and the condensation temperature of the refrigerant in the condenser, and the predetermined setting of the rectifier. This type of absorber has a control mechanism that detects the difference in temperature between the upper and lower points of This configuration is provided for a refrigerator.

(E) Effect The present invention provides the following effects by using the control mechanism to bring the difference between the inflow temperature of the refrigerant gas from the rectifier to the decentralizer and the condensation temperature of the refrigerant in the condenser to a predetermined value [zero]. This type of absorption chiller has the function of maintaining an almost equilibrium state between the refrigerant gas in the upper part of the rectifier and the refrigerant liquid in the condenser, increasing the purity of the refrigerant supplied to the evaporator to nearly 100% (99.99%). In addition, the control mechanism allows the difference between the respective temperatures at the upper and lower two points of the rectifier to be set to a set value [this set value is appropriately selected depending on the position of the upper and lower two points]. ], this type of absorption refrigerating machine can be provided with the function of adjusting the amount of refrigerant recirculated from the dephlegmator to the rectifier to an approximately optimum value without excess or deficiency.

By providing this type of absorption refrigerator with such a function (work), its performance can be maintained higher than that of conventional absorption refrigerators of this type.

(F) Embodiment FIG. 1 is a schematic structural diagram showing an embodiment of this type of absorption refrigerator according to the present invention.

In Fig. 1, 1 is an absorption liquid (hereinafter referred to as concentrated liquid) that has a built-in heater 2 and has absorbed a large amount of refrigerant.
A generator 3 gasifies and separates the refrigerant from the absorption liquid by heating and boiling the refrigerant, a rectifier 3 separates absorbent components from the rising refrigerant gas stream, and a rectifier 4 is sent from the rectifier 3. This is a partial condenser in which the incoming gas stream is cooled by a heat exchanger 5 for final separation of absorbent components. 6 has a heat exchanger 7, and 10 is an evaporator in which the heat exchanger 7 gives heat to the liquid refrigerant that is liquefied in the condenser 8, lowers the pressure in the pressure reducing valve 9, and is sprayed to vaporize the liquid refrigerant; Absorption liquid whose refrigerant concentration has been reduced by separating the refrigerant (hereinafter referred to as diluted liquid)
The refrigerant gas vaporized in the evaporator 6 is absorbed by reducing the pressure with the pressure reducing valve 11 and dispersing it from the disperser 12, thereby continuously absorbing heat from the fluid flowing through the heat exchanger 7. 14, 5 to the outside of the machine (operating as an absorption heat pump), or supplying fluid (chilled water, ice-making brine, etc.) whose temperature has been lowered as it flows through the heat exchanger 7 (as an absorption chiller). The concentrated liquid that has absorbed the refrigerant in this absorber is transferred from the liquid disperser 17 to the lower part of the rectifier 3 via the solution heat exchanger 16 by the absorption liquid pump 15. The refrigerant is spread over the material 18 and flows down into the generator 1 in contact with the gas stream rising from the generator 1, where the refrigerant is separated again. Note that 19 is a liquid receiver that is placed on the upper part of the generator 1 and also serves as a liquid disperser. Also,
20 is a filling material above the rectifier 3, and by spraying the refrigerant liquefied in the dephlegmator 4 to this filling material, the refrigerant is refluxed from the dephlegmator to the rectifier 3.
The purity of the refrigerant gas rising through the rectifier 3 is increased. 21, 22, 23 are pipes through which a dilute liquid flows; 24, 25, 26 are pipes through which a concentrated liquid flows; 27 are pipes through which an absorption liquid and a refrigerant flow;
8 is a liquid refrigerant distributor of the evaporator 6, 29 and 30 are pipes through which refrigerant gas flows, 31 and 32 are pipes through which the liquid refrigerant flows, and 33 is a pipe through which the liquid refrigerant flows back. Further, 34 and 35 are pipes connected to the heat exchanger 7, and 36, 37, 38, and 39 are the heat exchangers 13 and 1.
4 and 5 are connected in series, and 40 is a three-way valve V.
This is a bypass pipe connected to pipes 38 and 39 via.

S ₁ , S ₂ , S ₃ , and S ₄ are the pipe line 29 and the condenser 8, respectively.
Bottom, point A located at the top of rectifier 3, rectifier 3
This is a temperature detector installed at point B located at the bottom of the screen. and C is the temperature sensor S ₁ , S ₂ , S ₃ and S ₄
By controlling the degree of opening of the three-way valve V while receiving a signal from The difference between the temperatures detected by temperature detectors S ₁ and S ₂ approaches the set value [zero], and the difference between the temperatures detected by temperature detectors S ₃ and S ₄ approaches the set value [for example, the temperature difference in Figure 2]. This is a controller that adjusts the distance to approach a]. This controller C has a built-in arithmetic circuit composed of a microprocessor unit and the like.

Note that 41 is a dispersion device for liquid refrigerant provided above the filler 20 of the rectifier 3. Furthermore, 42,4
Reference numeral 3 denotes tubes connected to the heater 2, through which a heat source fluid flows.

Next, an example of the operation of the absorption refrigerating machine (hereinafter referred to as the present machine) configured as described above will be explained. Here, this machine is used as a refrigerator, and the heat exchanger 13,
It is assumed that cooling water is made to flow through 14 and 5 in sequence.

During operation of this machine, for example, if the outside temperature rises and the temperature of the cooling water flowing into the heat exchanger 5 of the dephlegmator 4 increases, the amount of liquefied refrigerant in the dephlegmator 4 begins to decrease. At the same time, the vapor pressure near the top of the dephlegmator 4 and rectifier 3 begins to rise. and,
The recirculation amount of the refrigerant liquid from the demultiplexer 4 to the rectifier 3, that is, the amount of refrigerant liquid sprayed to the filler 20, decreases and the rectification efficiency of the rectifier 3 begins to decrease.
In other words, the difference between the temperature of the refrigerant gas flowing into the condenser 8 and the temperature of the refrigerant liquid in the condenser 8 increases, and the equilibrium state is disrupted.
The purity of the refrigerant flowing down to the evaporator 6 begins to decrease.

In such a case, in this machine, first, the opening degree of _the bypass pipe 40 side of the three _- way valve V is decreased, while the opening degree of the heat exchanger 5 side is decreased via the controller C based on the signals from the temperature detectors S 1 and S 2. The temperature is increased, and the amount of heat exchanged between the refrigerant and the cooling water in the dephlegmator 4 is controlled to increase. As a result, the amount of refrigerant liquefied in the dephlegmator 4 increases, the amount of refrigerant returned to the rectifier 3 increases, and the temperature of the refrigerant gas near the top of the rectifier 3 decreases. The difference between the temperature of the refrigerant and the temperature of the refrigerant in the condenser 8, that is, the difference between the temperatures detected by the temperature detectors S ₁ and S ₂ approaches the set value [0° C.]. When this difference becomes approximately zero, the control of the three-way valve V by the signals from the temperature detectors S ₁ and S ₂ (hereinafter referred to as first control) is completed. Next, the _{three -} way valve V is controlled (hereinafter referred to as
(referred to as second control) is performed.

Figure 2 is a diagram showing the temperature inside the rectifier 3 in relation to the refrigerant reflux amount for each height of the rectifier 3, with the vertical axis representing the height, the horizontal axis representing the temperature, and the parameter representing the refrigerant. It shows the amount of reflux. In Figure 2, curve A plots the temperature at each height at the optimum reflux rate; the area to the right of curve A represents the area with insufficient reflux rate, and the area to the left of curve A represents the area with excess reflux rate. It represents. For example, curve B plots the temperature at each height when the reflux amount is less than the optimum value, and curve C plots the temperature at each height when the reflux amount is greater than the optimum value. And the temperatures T ₁ , T _{2 , for each height h 1 ,} h ₂ , h ₃ ,
T ₃ is adapted to be sensed by temperature detectors S ₁ , S ₃ and S ₄ , respectively.

When the cooling water temperature increases during operation of this machine and the refrigerant recirculation amount begins to decrease as described above, and the temperature at each height in the rectifier 3 enters the region represented by curve B, for example, the first By controlling the temperature shown in Figure 2
T _c [sensed temperature of temperature sensor S ₂ ] and temperature T ₁ [sensed temperature of temperature sensor S ₁ ] are controlled so that they are equal, and the refrigerant recirculation amount is optimized [to the left]
will be adjusted. However, as is clear from FIG. 2, the region where the temperatures T _c and T ₁ are equal includes not only the optimum region of the refrigerant recirculation amount but also the excess region. That is, it can be seen that the refrigerant recirculation amount cannot necessarily be optimally adjusted by only the first control. For example, when the recirculation amount of the refrigerant becomes excessive due to the first control and the temperature at each height of the rectifier 3 is shown by the curve c, the difference between the temperatures sensed by the temperature detectors S ₃ and S ₄ is b (See Figure 2), and the difference a in the optimal reflux amount [See Figure 2], that is, the set value a
Become bigger. In such a case, by the second control, the degree of opening of the three-way valve V on the bypass pipe 40 side is corrected to be increased, while the degree of opening on the heat exchanger 5 side is corrected to be decreased, and the degree of opening on the side of the heat exchanger 5 is corrected to In other words, the amount of heat exchanged between the refrigerant and the cooling water in the demultiplexer 4 is modified to decrease, and the amount of refrigerant liquefied in the demultiplexer 4 is modified to reduce the amount of refrigerant returned to the rectifier 3.
Then, when the difference in temperature sensed by the temperature detectors S ₃ and S ₄ becomes almost equal to the set value a, that is, when the refrigerant recirculation amount becomes almost optimum, the opening degree of the three-way valve V is fixed, and the opening degree of the three-way valve V is fixed. 2 control is completed.

Additionally, if the temperature of the cooling water flowing into the heat exchanger 5 of the dephlegmator 4 decreases during operation of this machine and the amount of refrigerant liquefied in the dephlegmator 4 increases, the amount of refrigerant returned becomes excessive. Therefore, the second control as described above is performed to adjust the recirculation amount to approximately the optimum amount. In this case, as is clear from Figure 2, the temperature
Since the difference between T _c and T ₁ , that is, the difference between the temperatures sensed by the temperature detectors S ₁ and S ₂ is almost zero, there is no need to perform the first control.

In addition, in this machine, instead of controlling the opening degree of the three-way valve V, the opening degree of the valve V ₀ provided in the pipe line 33 is controlled to adjust the liquid level in the dephlegmator 4, thereby controlling the refrigerant gas. Adjust the heat transfer area of the heat exchanger 5 in contact with the
The amount of heat exchanged may be adjusted. When controlling the valve V ₀ , the amount of heat exchanged in the demultiplexer 4 can be adjusted, and at the same time, the amount of refrigerant recirculation can also be directly adjusted, which has the advantage of higher control accuracy than when controlling the three-way valve V. be. Furthermore, the three-way valve V and the valve
Combination control with V ₀ is also possible.

FIG. 3 is a diagram showing a schematic configuration of a demultiplexer in another embodiment of this type of absorption refrigerating machine according to the present invention, and shows another example of a means for adjusting the amount of heat exchanged in the demultiplexer. It is. In Figure 2, the first
Components similar to those shown in the figure are given the same reference numerals. In this embodiment, instead of the heat exchanger 5 shown in FIG. 1, heat exchangers H ₁ , H ₂ ,
H ₃ and H ₄ are arranged in a demultiplexer 4,
Moreover, instead of the cooling water from these heat exchangers 14, cooling water is supplied from another water source. P ₁ , P ₂ , P ₃ and P ₄ are respectively heat exchangers H ₁ ,
It is a pipe connected to H ₂ , H ₃ and H ₄ , and V ₁ , V ₂ ,
V ₃ and V ₄ are on-off valves provided for pipes P ₁ , P ₂ , P ₃ and P ₄ , respectively. These opening/closing valves are controlled to open and close by signals from temperature detectors S ₁ , S ₂ , S ₃ , and S ₄ via the controller C, and the amount of heat exchanged between the refrigerant gas and the cooling water in the demultiplexer 4 is adjusted. It is becoming more and more common. Note that the temperature sensor S ₂ may be provided in the tube 31, the bottom of the decentralizer 4, or the tube 33 instead of being provided at the bottom of the condenser 8.

In addition, in this type of absorption refrigerator according to the present invention, changes in the internal cycle due to changes in external conditions other than the cooling water temperature, such as changes in load or changes in the heating amount of the generator 1, etc. concentration of absorption liquid,
Even if the gas-liquid equilibrium state is disrupted due to changes in the saturation temperature, saturated vapor pressure, purity of the circulating refrigerant, saturation temperature, or saturated vapor pressure, resulting in an excess or deficiency in the refrigerant recirculation amount, The first control returns the gas and liquid in the vicinity of the top of the rectifier 3, the decentralizer 4, and the condenser 8 to an equilibrium state, and improves the purity of the liquid refrigerant flowing to the evaporator 6.
Since it is maintained at nearly 100% [99.99%] and the second control adjusts the refrigerant recirculation amount to near the optimum value, efficient refrigeration performance is achieved. In this case, although not shown, it goes without saying that control for adjusting the heating amount of the generator 1 to match the load is carried out in the same manner as in the conventional absorption refrigerator of this type.

(g) Effects of the Invention As described above, in this type of absorption refrigerator according to the present invention, the difference between the temperature of the refrigerant gas flowing into the demultiplexer and the condensation temperature of the refrigerant in the condenser is set to almost zero. value] to maintain the gas-liquid equilibrium state, and to bring the temperature difference between two predetermined points of the rectifier closer to the set value to reduce the amount of refrigerant recirculated from the decentralizer to the rectifier. A control mechanism is provided to adjust the amount of heat exchanged between the refrigerant and the cooling fluid in the dephlegmator so as to maintain it at approximately the optimum value, so the purity of the refrigerant sent to the evaporator is maintained high, and the purity of the refrigerant sent to the evaporator is maintained at a high level. Since just the right amount of refrigerant is sent to the refrigerant, the performance of this type of absorption refrigerator can be demonstrated well.

[Brief explanation of the drawing]

Fig. 1 is a schematic structural explanatory diagram showing an embodiment of this type of absorption refrigerator according to the present invention, and Fig. 2 shows the temperature inside the rectifier and the flow of refrigerant to the rectifier at each height of the rectifier. A diagram showing the relationship with the reflux amount, and FIG. 3 is a schematic diagram illustrating the configuration of a demultiplexer in another embodiment of this type of absorption refrigerator according to the present invention. 1... Generator, 3... Rectifier, 4... Decentralizer,
5... Heat exchanger, 6... Evaporator, 8... Condenser,
10... absorber, 18, 20... filler, 29,
30, 31, 32, 33...pipeline, 36, 37,
38, 39...pipe, 40...bypass pipe, C...
Controller, H ₁ , H ₂ , H ₃ , H ₄ ...Heat exchanger, P ₁ ,
P ₂ , P ₃ , P ₄ ... Pipe, S ₁ , S ₂ , S ₃ , S ₄ ... Temperature detector, V ... Three-way valve, V ₀ ... Valve, V ₁ , V ₂ , V ₃ ,
V ₄ ...Open/close valve.

Claims (1)

[Claims] 1 Generator, rectifier, dephlegmator, condenser, evaporator,
In an absorption refrigerating machine with an absorber connected via piping, the difference between the temperature of the refrigerant gas flowing into the demultiplexer and the condensation temperature of the refrigerant in the condenser, and the difference between the temperatures at two predetermined points above and below the rectifier. An absorption refrigerating machine characterized by being equipped with a control mechanism that detects the difference between the two and adjusts the amount of heat exchanged between the refrigerant in the demultiplexer and the cooling fluid of the refrigerant so that each of these differences approaches a set value.