JPH058351B2 - - Google Patents

Description

[Detailed Description of the Invention] (a) Field of Industrial Application The present invention relates to an improvement in a type of dual-effect absorption refrigerator that is equipped with a pump in the middle of a concentrated solution flow path from a low-temperature generator to a low-temperature solution heat exchanger. .

(b) Prior art The above-mentioned type of dual-effect absorption refrigerator has the function of promoting the flow of concentrated solution using a pump, and has the advantage of improving the performance of the machine because it can increase the heat exchange rate of the low-temperature solution heat exchanger. have. On the other hand, pumps for concentrated solutions suck in and discharge a nearly constant amount of solution regardless of fluctuations in the amount of liquid in the low-temperature generator. There is a drawback that cavitation of the pump occurs when the outflow amount of the solution decreases, leading to failure of the pump. To overcome this drawback, the conventional technology for the above-mentioned type of double-effect absorption refrigerator is to provide the low temperature generator with a liquid level relay for controlling the start/stop of the concentrated solution pump, thereby controlling the amount of solution in the container. It has been proposed to prevent cavitation by stopping the concentrated solution pump when the concentration decreases (see, for example, Japanese Patent Laid-Open No. 126561/1983).

(c) Problems to be solved by the invention In the conventional dual-effect absorption refrigerator as described above, it is possible to prevent an excessive decrease in the amount of solution in the low temperature generator and cavitation of the concentrated solution pump. However, as the amount of concentrated solution sent to the absorber fluctuates widely as the concentrated solution pump starts and stops, there is a problem in that it causes significant hunting in the refrigeration output, resulting in unstable operation. .

In view of these problems, the present invention has developed a dual-effect absorption system of the above type that can easily prevent cavitation without controlling the start/stop of the pump for concentrated solutions, and can continue stable operation. The purpose is to provide refrigerators.

(d) Means for Solving the Problems The present invention, as a means for solving the above-mentioned problems, provides a solution flow path from the concentrated solution flow path on the suction side of the concentrated solution pump and the low temperature solution heat exchanger to the absorber. This is a dual-effect absorption refrigerator of the type described above, in which the high temperature generator is equipped with a liquid level relay for controlling the pump for dilute solutions, in which the lines are connected by pipes.

(e) Effect In the dual-effect absorption refrigerator according to the present invention,
A pipe connecting the concentrated solution flow path on the suction side of the concentrated solution pump and the concentrated solution flow path on the outlet side of the low temperature solution heat exchanger functions as a concentrated solution supply path to the suction side of the concentrated solution pump. If the amount of concentrated solution flowing out from the low-temperature generator decreases due to load or other external conditions, the reduced amount is replenished from the conduit that serves as the concentrated solution replenishment line to the concentrated solution pump. Since a fixed amount of concentrated solution flows in, cavitation can be prevented while the pump remains in operation.

Therefore, the dual-effect absorption refrigerator of the present invention has the following features:
Hunting of the refrigeration output, which occurs in conventional systems that prevent cavitation by controlling the start and stop of the pump for concentrated solutions, can be greatly alleviated, and more stable operation can be continued. Furthermore, by providing the high temperature generator with a liquid level relay for controlling the pump for dilute solutions, the amount of solution in the container can be maintained within a predetermined range and uneven distribution of the solution in the solution circulation path can be reduced. Furthermore, even more stable operation can be continued.

(F) Embodiment FIG. 1 is a schematic structural explanatory diagram showing an embodiment of a dual-effect absorption refrigerator according to the present invention. In Figure 1, 1 is a high temperature generator, 2 is a generation condenser consisting of a low temperature generator 3 and a condenser 4, 5 is an evaporator and absorber consisting of an evaporator and an absorber 7, 8 and 9 are low temperature and high temperature solutions, respectively. In the heat exchanger, P _R is a pump for refrigerant liquid, P _LA is a pump for dilute solution, and P _HA is a pump for concentrated solution.
Pipe 12 through which the refrigerant liquid flows, pipes 13 and 14 through which the refrigerant liquid flows back, and pipes 15 and 1 through which the dilute solution is sent.
6, 17, 18, connected by pipes 19, 20 through which a solution of intermediate concentration (hereinafter referred to as intermediate solution) flows, and pipes 21, 22, 23 through which a concentrated solution is sent, so that the refrigerant [water] and the solution [brominated] A circulation path for a lithium aqueous solution is formed.

B is the burner of the high temperature generator 1, 24, 24... are heating tubes through which combustion gas flows, 25 is a duct for discharging the combustion gas, 26 is the heater of the low temperature generator 3, 27 is the cooler of the condenser 4, 28 is the heat exchanger of evaporator 6,
29 is a cooler for the absorber 7. 30, 31 are cold water pipes connected to the heat exchanger 28, 32,
33 and 34 are cooling water pipes in which coolers 29 and 27 are connected in series. Further, 35 is a fuel supply pipe to the burner B, and this pipe is equipped with a control valve _VF . Note that S _T is a sensor that detects the temperature of the cold water on the outlet side of the heat exchanger 28, and the opening degree of the control valve V _F is adjusted via the temperature regulator C based on a signal from this sensor. And also, LCR
is a liquid level relay for controlling the discharge amount of the dilute solution pump P _LA , and this relay is installed in the high temperature generator 1.

Further, T is a conduit connecting conduit 21 and conduit 23, through which a part of the concentrated solution on the discharge side of the concentrated solution pump _PHA can be returned to its suction side.

In this type of absorption chiller (hereinafter referred to as this machine) configured in this way, for example, the sensor S _T
The dilute solution flow rate is controlled by changes in the load, heating amount, cooling water temperature, and other external conditions, such as controlling the opening of the control valve V _F and the discharge amount of the dilute solution pump P _LA via the temperature controller C. When the intermediate solution flow rate and the outflow amount of concentrated solution from the low temperature generator 3 decrease, concentrated solution is replenished to the suction side of the concentrated solution pump _PHA via pipe T by the amount of the decrease in the concentrated solution outflow amount. Therefore, cavitation can be easily and reliably prevented without controlling the pump on/off or controlling the discharge amount. That is, in this machine, the outflow amount X of concentrated solution from the low temperature generator 3, the concentrated solution flow rate Y of the pipe T, and the liquid suction amount of the concentrated solution pump _PHA [in other words, the liquid discharge amount]
The relationship with Q is expressed by the following formula [1].

X+Y=Q [constant] ... [1] Furthermore, if the amount of concentrated solution flowing into the absorber 7 is Z, the relationship between this Z and the above flow rate is expressed by the equation [2].

Z=Q-Y=(X+Y)-Y=X... [2] As is clear from the [2] equation, the amount of concentrated solution flowing out from the low temperature generator 3 and the amount of concentrated solution flowing into the absorber 7 are the same. is maintained. Therefore, in this machine, even if the amount of solution in and out of the low temperature generator 3 changes due to changes in the heating amount of the high temperature generator 1, which is controlled according to the load, the cooling water temperature, etc., the concentrated solution pump P _HA Similar to the conventional dual-effect absorption refrigerator that does not use a refrigerator, the amount of concentrated solution sprayed to the cooler 29 is adjusted according to the load, cooling water temperature, etc. Also, in this case,
The pump for concentrated solutions _PHA is controlled to start and stop in order to prevent cavitation. Unlike conventional dual-effect absorption refrigerators, the supply of concentrated solutions to the absorber 7 is not cut off or restarted. , and does not cause significant hunting in the refrigeration output.

In addition, this machine has a pump for dilute solutions.
Liquid level relay for _PLA discharge amount control or start/stop control
Since the LCR prevents the liquid level in the high temperature generator 1 from dropping or rising excessively, it also prevents the liquid level in the absorber 7 from rising or falling excessively, thereby preventing uneven distribution of the solution in these vessels. This also prevents the solution from being excessively unevenly distributed within the low temperature generator 3. As a result, stable operation can be continued. Note that a liquid level relay LCR may be provided in the absorber 7.

In this way, even when external conditions suddenly change, this machine can keep the concentrated solution pump P _HA running and prevent cavitation, thereby alleviating hunting of the refrigeration output and reducing the need for the low temperature solution heat exchanger. The heat exchange performance of 8 can be maintained at a high level, and the uneven distribution of the solution in the solution circulation path can be reduced by the action of the liquid level relay LCR, allowing stable and high-performance operation to continue.

Furthermore, in this machine, since the operation of the concentrated solution pump _PHA is not stopped, crystallization of the concentrated solution in the low temperature solution heat exchanger 8 is also prevented when the cooling water temperature drops.

In addition, in this machine, the connection position of the pipe T with the pipe 21 is set to be below the liquid level of the concentrated solution in the pipe 21 when the pressure difference between the low temperature generator 3 and the absorber 7 is at its maximum. Designed.

Furthermore, even when this machine is used as a heat pump, it is of course possible to continue stable and high-performance operation in the same way as when it is used as a refrigerator.

2, 3, and 4 are schematic structural explanatory diagrams showing other embodiments of the dual-effect absorption refrigerator according to the present invention, and in these figures, the same structure as that shown in FIG. 1 is shown. Components are given the same reference numerals. In FIG. 2, 36 is a dilute solution pipe branching from the pipe 17 and leading to the low temperature generator 3;
7 is a pipe line leading from the outlet of the high temperature generator 1 to the pipe line 21 via the high temperature solution heat exchanger 9. Also, the third
In the figure, 38 is a dilute solution pipe branching from the pipe 16 and leading to the low temperature generator 3 via the low temperature solution heat exchanger 8, and 39 is a pipe for dilute solution running from the high temperature generator 1 via the high temperature solution heat exchanger 9. This is the conduit that leads to the conduit 23.
Furthermore, in FIG. 4, 40 is a pipe line leading from the absorber 7 to the low temperature generator 3 via the second dilute solution pump P _LA2 and the low temperature solution heat exchanger 8;
Reference numeral 1 denotes a pipe line leading from the outlet of the high temperature generator 1 to the absorber 7 via the high temperature solution heat exchanger 9. In both of these embodiments, the dilute solution is sent to the generators 1 and 3, and the solution concentrated in each generator is returned to the absorber 7, in that the dilute solution is sent to the generator 1 and concentrated there. This differs from the embodiment shown in FIG. 1 in that it is made into an intermediate solution, which is then introduced into a generator 3, concentrated, and returned to an absorber 7, but otherwise has the same structure.

Also in the embodiments shown in FIGS. 2 to 4, the pipe T functions as a concentrated solution supply path for the concentrated solution pump _PHA , similar to that shown in FIG. Cavitation of the lever pump is prevented, and the pump also promotes the flow of concentrated solution in the cold solution heat exchanger 8 to improve its heat exchange performance, resulting in stable high performance against fluctuations in external conditions. can continue to drive.

(G) Effects of the Invention As described above, the present invention has the effect of preventing cavitation while keeping the concentrated solution pump operating even when the load, cooling water temperature, and other external conditions change rapidly and widely. , brings the effect of alleviating the hunting of the refrigeration (heat pump) output at this time and the effect of reducing the uneven distribution of the solution in the solution circulation path to a type of dual-effect absorption refrigerator equipped with a pump for concentrated solutions. At the same time, by being able to continue operating the concentrated solution pump, the heat exchange performance of the low-temperature solution heat exchanger is improved and the crystallization of the concentrated solution in this heat exchanger is prevented, resulting in stable and high-performance operation. This is of high practical value as it can provide a dual-effect absorption refrigerator of the type described above.

[Brief explanation of the drawing]

FIG. 1 is a schematic structural explanatory diagram showing one embodiment of a double-effect absorption refrigerator according to the present invention, and FIGS. 2, 3, and 4 are respective diagrams of the double-effect absorption refrigerator according to the present invention. It is a schematic configuration explanatory diagram showing another example. 1... High temperature generator, 2... Generation condenser, 3...
Low temperature generator, 4... Condenser, 5... Evaporative absorber,
6...evaporator, 7...absorber, 8,9...low temperature,
High temperature solution heat exchanger, P _LA ...Dilute solution pump, P _HA
...Concentrated solution pump, 15, 16, 17, 18,
19, 20, 21, 22, 23...pipeline, 36,
37, 38, 39, 40, 41...pipeline, P _LA2 ...
...Dilute solution pump, LCR...Liquid level relay, T...
...Pipeline.

Claims (1)

[Claims] 1 In a dual-effect absorption refrigerator equipped with a pump in the middle of a concentrated solution flow path from a low temperature generator to the inlet of a low temperature solution heat exchanger, absorption from the pump suction side of the concentrated solution flow path and the low temperature solution heat exchanger is A flow path connecting the concentrated solution flow path to the absorber is provided, and the high temperature generator is equipped with a liquid level relay for controlling a pump that sends the dilute solution from the absorber to the high temperature generator. A dual-effect absorption refrigerator.