JPH0378544B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention provides a dual-effect absorption refrigerator, in particular, a system in which a portion of a dilute solution discharged from a solution pump is sent to a low temperature generator.
The present invention relates to a dual-effect absorption refrigerator in which the remainder is directed to a high-temperature generator.

[Conventional technology]

A conventional refrigerator of this type has a configuration as shown in the flow diagram shown in FIG.

In Fig. 3, 1 is an absorber, 2 is an evaporator, and 3
is a high temperature generator, 4 is a low temperature generator, 5 is a condenser, 6
is a high temperature heat exchanger, 7 is a low temperature heat exchanger, 8 is a solution pump, 9 is a refrigerant pump, 10 is an orifice, 11
1 is a liquid level regulator, 12 is a cold water temperature detector, 13 is a cold water temperature signal generator, 14 is a fuel supply amount regulator, 1
5 shows the absorber spray piping.

The dilute solution from the absorber 1 is pumped up by a solution pump 8, heated by heat exchangers 6 and 7, and then guided to a high temperature generator 3 and a low temperature generator 4. The liquid level of the high-temperature generator 3 should be adjusted to prevent dry firing when using a direct-fired generator as shown in Fig. 3, for example.
A liquid level adjustment mechanism 11 is provided. The solution returned from the high-temperature generator has a differential pressure △Ph between the high-temperature generator pressure during operation and the absorber spray piping 15, and the liquid head △.
Returned by Hh. The low temperature regenerator is similarly returned by the pressure difference ΔPl and the liquid head ΔHl. here,
Considering an absorption refrigeration cycle that uses LiBr solution as an absorbent and water as a refrigerant, it can be said that it has a return pressure potential (return ability) as shown in FIG. However, under operating conditions, the flow loss of the solution
There are P _Lh and P _Ll , which must be subtracted.
The pressure potential from the low temperature generator is approximately balanced with the flow loss, and the excess pressure is transferred to the liquid head △Hl
becomes smaller (lower temperature generator return liquid level falls) and disappears. However, as shown in Figure 4, the pressure potential of the high temperature generator is
Since the proportion of the pressure difference △Ph is larger than that,
Excess pressure must be reduced by a throttling mechanism such as an orifice. Under normal operating conditions, the pressure potential of the high temperature generator is approximately 6 mLiBr aqueous solution column, and 50 to 70% of this is often reduced in pressure by a throttling mechanism such as an orifice, but at startup or when the cooling water temperature is low. , the pressure potential is normal
If it is less than 50% and a fixed throttle orifice is used, the return capacity will be insufficient and the return liquid level in the high temperature generator will rise and △Hh will increase. During ability, liquid head △
The occupancy rate of Hh is small, and if the liquid level is raised too much, liquid entrainment evaporation (carry-over phenomenon) occurs in the high-temperature generator, resulting in a decrease in efficiency. The system is configured to reduce the amount of feed to the high temperature generator when the liquid level rises. If a bellows seal valve with good shutoff performance is used in this liquid level regulator 11, it is not only expensive, but also has the disadvantage that the bellows seal part is easily damaged and has a short lifespan. For this reason, butterfly-shaped self-powered float valves are often used, which have poor shutoff performance but are inexpensive and can operate smoothly. For this reason, when the pressure of the high temperature generator is low as mentioned above, the return capacity is insufficient and the liquid level rises, resulting in liquid entrainment and cavitation of the solution pump due to a drop in the liquid level in the absorber. There were flaws. Additionally, since the solution is sent to the low temperature generator without the absorption refrigeration cycle being formed at startup, the steam generated by heating in the high temperature generator is used to heat the solution, making it difficult for the pressure in the high temperature generator to reach the specified potential. Most of the heat of the heated solution is absorbed by the absorber 1.
There was a loss in that the water was wasted into the cooling water.

Furthermore, when the refrigeration load is high and the cooling water temperature is low, the pressure potential of the high temperature generator becomes △P.
Since the liquid level adjustment mechanism described above reduces the amount of solution sent to the high temperature generator, as shown in Figure 5,
The concentration range in the high temperature generator becomes too large,
There was a drawback that there was a risk of crystal formation.

[Structure of the invention]

The present invention forms a double-effect absorption refrigeration cycle from an absorber, an evaporator, a condenser, a low-temperature generator, a high-temperature generator, a solution heat exchanger, a solution pump, and a solution path and a refrigerant path connecting these, A portion of the solution sent from the solution pump is sent to the low temperature generator,
In a dual-effect absorption refrigerating machine configured such that the remainder is guided to a high-temperature generator and having a liquid level adjustment mechanism for maintaining a liquid level in the high-temperature generator, a liquid return ability detection or prediction mechanism from the high-temperature generator is provided. A solution system for sending to the low-temperature regenerator and a return solution system from the low-temperature regenerator are connected via an on-off valve, and a signal from a liquid return capacity detection or prediction mechanism from the high-temperature regenerator is used to connect the solution system to the low-temperature regenerator. This is a dual-effect absorption refrigerator characterized in that part or all of the sent liquid is bypassed to the return solution system from the low-temperature regenerator.

In order to solve the above-mentioned drawbacks, the present invention is configured to maintain the pressure potential of the high temperature generator above a predetermined value.

An embodiment of the present invention will be described below with reference to FIG. The pressure potential of the high temperature generator 3 is output by the pressure sensor 22 and the controller 23, and when the liquid return capacity of the high temperature generator is insufficient, the solution sent to the low temperature generator 4 is passed through the piping 21 and the on-off valve 20 to the low temperature generator. A predetermined amount is bypassed to the vessel return solution system. Therefore, the amount of heat exchanged in the low-temperature generator is reduced, and as a result, the pressure potential of the high-temperature generator is increased, and the liquid return capacity is controlled to be increased. The opening degree of the on-off valve 20 is controlled so that at startup, the pressure potential of the high-temperature generator is low, so it becomes fully open, and when the entire amount bypasses the low-temperature generator and the pressure potential becomes large, it becomes fully open. Therefore, the pressure rises quickly at startup, and even a liquid level adjustment mechanism with poor shutoff performance can be controlled. In addition, since there is no heating in the low temperature generator 4 at this time, the amount of heat radiated to the cooling water by the absorber can be reduced as a result.
The rise time can be shortened.

Also, when the pressure potential of the high temperature generator becomes low due to low cooling water temperature or small refrigeration load, the pressure potential of the high temperature generator can be detected using the same method and the heat in the low temperature generator can be detected. A similar effect can be achieved by reducing the exchange rate and increasing the pressure potential.

The liquid return ability (pressure potential) in the high temperature generator can be determined by using a pressure sensor as in this embodiment, or by the solution temperature or refrigerant temperature around the high temperature generator. Furthermore, it is also possible to directly detect the liquid level height of the high temperature generator to determine whether the liquid return ability is insufficient.

FIG. 2 shows an absorption cycle different from that in FIG. 1, and each symbol shown in FIG. 2 has the same meaning as in FIG. 1. In the example shown in FIG. 2, the return head ΔHh of the solution from the high temperature generator has a negative pressure, so that a more remarkable effect is exhibited than in the absorption cycle shown in FIG. 1.

The present invention detects the liquid return capability of a high temperature generator,
If the capacity is insufficient, the amount of liquid sent to the low temperature generator is reduced by bypassing the return solution system, reducing the amount of heat transferred in the low temperature generator.
It is configured to raise the pressure of the high temperature generator above a predetermined value.

Furthermore, the present invention includes prediction of a situation in which the liquid return capacity is inevitably insufficient when considering an absorption refrigeration cycle at startup, stop dilution, and the like. Specifically, for example, at startup, the solution in the high-temperature generator is at a low temperature and there is little refrigerant vapor generated, so it is naturally expected that the pressure potential will be low at such times. Since the heating amount of the high temperature generator can be determined from the opening degree of the fuel supply amount control valve, etc., it is possible to predict the time until the liquid return ability is exerted. By controlling the on-off valve 20 to be fully open during this time, the above-mentioned starting characteristics can be obtained.

〔Effect of the invention〕

As described above, the present invention is configured to maintain the liquid return capacity (pressure potential) of the high-temperature generator at a predetermined value or higher. 1. Safe absorption refrigeration without the risk of crystal formation even when the cooling water temperature is low. It can be driven on a cycle.

2. It is possible to prevent the liquid entrainment phenomenon due to a rise in the liquid level in the high-temperature regenerator, and also to prevent the cavitation of the solution pump that occurs at that time.

3. A high-temperature generator liquid level adjustment mechanism with excessive throttling characteristics is not required, and an inexpensive and smooth drive control unit can be provided.

4. At startup, the startup time is faster, heat radiation can be suppressed as much as possible, and it is also favorable for energy saving.

etc., it has remarkable effects.

[Brief explanation of drawings]

Figures 1 and 2 are a schematic flow diagram of the dual-effect absorption refrigerator of the present invention, Figure 3 is a schematic flow diagram of a conventional absorption refrigerator, and Figure 4 is a diagram of the absorber in a high temperature generator and a low temperature generator. FIG. 5 is a diagram for explaining the pressure difference and the proportion of the liquid head that affect the spray pipe pressure, and is a diagram showing the relationship between the high temperature generator pressure and the solution concentration range. 1...Absorber, 2...Evaporator, 3...High temperature generator, 4
...low temperature generator, 5...condenser, 6...high temperature heat exchanger,
7... Low temperature heat exchanger, 8... Solution pump, 9... Refrigerant pump, 10... Orifice, 15... Absorber spray piping, 20... Opening/closing valve, 22... Pressure sensor, 23... Controller.

Claims (1)

[Claims] 1. A double-effect absorption cycle is formed by an absorber, an evaporator, a condenser, a low-temperature generator, a high-temperature generator, a solution heat exchanger, a solution pump, and a solution path and a refrigerant path connecting these. , a double pump configured such that a part of the solution sent from the solution pump is guided to the low temperature generator and the remaining part is guided to the high temperature generator, and has a liquid level adjustment mechanism that maintains the liquid level in the high temperature generator. In the effective absorption refrigerator, a liquid return capacity detection or prediction mechanism from the high temperature generator is provided, and a solution system to be sent to the low temperature regenerator and a return solution system from the low temperature regenerator are connected via an on-off valve, and the high temperature A dual system characterized in that part or all of the liquid sent to the low-temperature regenerator is bypassed to the return solution system from the low-temperature regenerator in response to a signal from a liquid return capacity detection or prediction mechanism from the regenerator. Effective absorption refrigerator. 2. The device according to claim 1, wherein the liquid return capability detection mechanism is a liquid level detection mechanism of a high temperature generator. 3. Claim 1, wherein the liquid return capability detection mechanism is a pressure or temperature detection mechanism of a high temperature generator.
Apparatus described in section. 4. The device according to claim 1, wherein the liquid return ability prediction mechanism is a time detection mechanism at the time of starting and/or stopping.