JPS5852462Y2 - Fusible device with backflow prevention valve for absorption refrigerator - Google Patents

Description

[Detailed description of the invention] Fig. 1 shows a conventional absorption refrigerator, in which 1 is an evaporator, 2 is an absorber, 3 is a condenser, and 4 is a low-pressure regenerator, all of which are composed of a large number of tube groups. Chilled water flows in the pipes of the evaporator 1, cooling water flows in the pipes of the absorber 2 and condenser 3, and the low pressure regenerator 4
Steam is flowing inside the pipe.

These are housed inside a tubular shell that forms a sealed container, and the inside of the shell is kept in a vacuum by completely excluding air. They are fixed with an extension band or the like, and have a structure that allows the required fluid to flow into the pipes via headers.

5 is a high-pressure regenerator which similarly consists of a large number of tube groups and in which a heating medium such as steam supplied from a heat source flows, 6 is a first heat exchanger, 7 is a second heat exchanger, and 8 is a heat recovery device. 9 is a refrigerant pump, 10 is an absorption liquid circulation pump, 11 is a refrigerant, 12
indicates dilute absorption liquid.

In FIG. 1, refrigerant vapor evaporated by cooling action in an evaporator 1 is absorbed by an absorption liquid in an absorber 2, and the concentration of the absorption liquid decreases and is stored in the lower part.

This diluted absorption liquid 12 is passed through the pipe 1 by an absorption liquid circulation pump 10.
3. The refrigerant is sent to the high-pressure regenerator 5 via the first heat exchanger 6, piping 14, second heat exchanger 7, and piping 15, and is heated with steam to evaporate and separate the absorbed refrigerant.

The intermediate concentration absorption liquid whose concentration has increased after separating the refrigerant passes through the pipe 16 and exchanges heat with the dilute absorption liquid in the second heat exchanger 7, and after its temperature drops, it passes through the pipe 17 and enters the heat recovery unit 8, where it is high-pressure regenerated. Vessel 5
The refrigerant is heated again by the drain of the heated steam discharged from the absorbent via the pipe 21, and the refrigerant is evaporated and separated, and the absorbed liquid becomes concentrated and enters the pipe 23 and then enters the low-pressure regenerator 4.

The high-temperature and high-pressure refrigerant vapor generated in the high-pressure regenerator 5 is led to the low-pressure regenerator 4 via a pipe 20, heats the absorption liquid, further evaporates and separates the refrigerant from the absorption liquid, and evaporates in the heat recovery unit 8. The condenser 3 along with the refrigerant vapor flowing through the pipe 24
The refrigerant enters the water, takes heat from the cooling water, and condenses.

The concentrated absorbent liquid whose concentration has increased in the low-pressure regenerator 4 passes through the pipe 18 and exchanges heat with the dilute absorbent liquid in the first heat exchanger 6 to give heat to the dilute absorbent liquid. It enters the absorber 2 and performs the absorption action again.

On the other hand, the refrigerant that heats the absorption liquid in the low-pressure regenerator 4 and condenses itself enters the condenser 3 and is cooled by cooling water, and then passes through the aforementioned heat recovery device 8.
It returns to the evaporator 1 together with the refrigerant from the low-pressure regenerator and performs a cooling action.

When the above operating state is shown in terms of temperature, concentration, and pressure at each part when water is used as the refrigerant and lithium bromide aqueous solution is used as the absorption liquid, ■ in Figure 2 shows the rare absorption at the inlet of the first heat exchanger 6. ■ is the dilute absorption liquid at the inlet of the second heat exchanger, ■ is the dilute absorption liquid at the outlet of the second heat exchanger, ■ is the intermediate concentration absorption liquid at the outlet of the high-pressure regenerator 5, and ■ is the dilute absorption liquid at the outlet of the second heat exchanger 7. ■ indicates the state of the intermediate concentration absorption liquid at the outlet of the heat recovery device, ■ indicates the state of the concentrated absorption liquid at the outlet of the low pressure regenerator 4, and ■ indicates the state of the concentrated absorption liquid at the outlet of the first heat exchanger 6. show.

Note that the pressure in the lower shell chamber 30 of the closed container housing the evaporator 1 and absorber 2 varies depending on the required cold water temperature, etc., but is usually around 0.01 kg/cm2abs.

On the other hand, the shell upper chamber 31 containing the condenser 3 and low pressure regenerator 4 is normally 0.1k, although it varies depending on the cooling water temperature etc.
g/cm2abs, which is always higher than the lower shell chamber 30 which is partitioned by a partition plate.

In addition, the pressure inside the high pressure regenerator 5 and the low pressure regenerator heat exchanger tube 20 is even higher, usually 0 + 9 kg/cm 2a
It is around bs.

In this way, the pressure inside the absorption refrigerator drops significantly during operation or storage.

In other words, the absorber, evaporator, etc. in the lower shell chamber are 6 to 7 m long.
Even in the low-pressure regenerator heat exchanger tube in the upper shell chamber, where the pressure is highest in mHg (absolute), and in the high-pressure regenerator, the pressure is 700 mmHg (absolute) or less.

For this reason, absorption refrigerators are built with a highly airtight structure.

The reason for this is that if air leaks from the outside, the performance of the absorption refrigerator will be significantly reduced and the corrosion resistance of the materials used will be significantly impaired.

For this reason, it is inappropriate to provide a mechanical safety valve such as in a general boiler or pressure vessel because it may cause a vacuum failure.

However, the amount of heating increases significantly, the absorber
If the temperature of the cooling water passing through the condenser becomes higher than the designed value, or if it is heated from the outside, the internal pressure may exceed atmospheric pressure.

A rupture disc may be provided to release the internal pressure when the pressure becomes high, but in the case of a rupture disc, it will not rupture unless the pressure rises to a certain extent in order to maintain airtightness.

To compensate for this drawback, the gas phase inside the absorption refrigerator is filled with refrigerant vapor, and since the relationship between pressure and temperature of this refrigerant vapor is 100°C at atmospheric pressure, this temperature can be used to Attempts have been made to dissolve fusible plugs.

However, if only a fusible plug is provided, there is a problem in that once it is dissolved, air will flow back into the interior until it is replaced.

The present invention solves the above-mentioned problems and makes it possible to prevent air from flowing back into the interior of the absorption refrigerator, that is, into the shell of the closed container when the fusible plug is melted.

The present invention will be explained below based on the embodiment shown in FIG.

In FIG. 3, reference numeral 41 denotes a valve box made of a cylindrical body of the present device, and a valve hole 48 formed at the bottom center of the valve box 41 is aligned with a through hole 44 formed on the outer surface of the shell upper chamber 31. Once in place, the valve box is fixed to the shell by welding.

A valve seat 52 is protruded around the valve hole 48, and a large valve chamber 50 is formed above the valve seat 52, and a passage 49 is formed in this valve chamber 50.
are set up in succession.

On the other hand, 43 is a cup-shaped non-return valve body which is fitted into the valve chamber 50 and passage 49 of the valve box 41, and whose bottom surface is seated on the valve seat 52 under normal conditions.

In addition, a plurality of through holes 53 are formed on the side surface of this backflow prevention valve body 43.
is perforated.

A fusible plug made of metal that easily melts at about 100° C. is attached to the upper end surface of the valve box 41 via a packing 47 that maintains airtightness by tightening bolts using a fixing plate 45.

The diameter d2 of the through hole 51 formed in the fixed plate 45 needs to be smaller than the outer diameter d1 of the check valve body 43.

That is, by setting d2<dl, shell 31
This is to prevent the valve body 43 from jumping out when the pressure inside a increases.

The device is attached to the shell so that under normal conditions, the valve body 43 seats and seals the valve seat 52 as shown in the figure under its own weight.

If heat is not insulated with such a mounting structure, the heat transmitted from the shell through the valve box 41 and valve body 43 to the fusible plug 42 will be radiated to the atmosphere, so the fusible plug portion will not be directly exposed to refrigerant vapor. Heat is transmitted.

Now, during normal operation or storage, the inside of the absorption refrigerator is in a vacuum, so the inside of the sealed container a, the valve chamber 50 and the passage 49 are
All parts are in a vacuum state, and airtightness with the outside is mainly maintained by force between the fusible plug 42 and the packing 4/and the packing 47 and the valve body 41, respectively.

When the pressure inside the low-pressure regenerator 4 abnormally rises due to an increase in the amount of heating, etc., and the pressure inside the closed container a increases, the check valve body 43 is pushed upward, and the refrigerant vapor flows into the valve chamber 5.
0, flows into the passage 49 and melts the fusible frame 42.

On the other hand, normal absorption refrigerators are equipped with a safety device that shuts off the heating source when the pressure rises and approaches atmospheric pressure, and the fusible frame 42 melts to release the internal refrigerant vapor and shut off the heating source. The internal pressure decreases to below atmospheric pressure.

At this time, the valve body 43 falls under its own weight and returns to the top of the valve seat 52, and the seated portion is kept airtight due to the difference between atmospheric pressure and internal pressure.

Therefore, even if the fusible frame 42 melts, there is almost no chance of air entering inside.

According to the present invention configured as described above, when the pressure inside the vessel falls below atmospheric pressure after the melting of the fusible frame attached to the shell when the pressure inside the closed vessel rises abnormally, the refrigerant vapor pushes it upward into the valve chamber. Since the non-return valve body which is attached to the container falls under its own weight and seats on the valve seat to form a seal, it is possible to prevent outside air from flowing into the container even if the fusible frame melts.

In particular, even when the absorption refrigerator is in operation, the fusible frame can be easily replaced because it is sealed from the outside with a backflow prevention valve, and even during storage, an inert gas can be filled inside to bring it up to atmospheric pressure. It can also be replaced without increasing the pressure.

[Brief explanation of drawings]

Figure 1 is a system diagram showing a conventional dual-effect absorption refrigerator;
The figure is a characteristic curve diagram showing the refrigeration cycle of Fig. 1, and Fig. 3 is a longitudinal sectional side view showing the embodiment of the present invention. 30: Lower shell chamber, 31: Upper shell, 41: Valve box, 42: Fusible frame, 43: Backflow Prevention valve body, 44, 51゜53
...Through hole, 45...Fixing plate, 46...
...Bolt, 47...Patsukin, 48...
... Valve hole, 49 ... Passage, 50 ...
・Valve chamber, 52... Valve seat.

Claims (2)

[Scope of utility model registration request] (1) An evaporator, an absorber, a condenser, and a regenerator are built in a sealed container, and for example, water is used as the refrigerant, lithium bromide aqueous solution is used as the absorption liquid, and a heat exchanger is arranged in the absorption liquid circulation system. In an absorption refrigerator, a fusible plug is attached to the shell that forms the container to prevent damage to the container due to an increase in internal pressure due to external heating, etc. After melting, the container temperature decreases and the internal pressure decreases to atmospheric pressure. A fusible device with a backflow prevention valve for an absorption refrigerator, characterized in that it is equipped with a backflow prevention valve that prevents outside air from flowing into the container when the following conditions occur. (2) Claim 1 of the Utility Model Registration Claim, wherein the valve element of the check valve is pushed upward by the refrigerant vapor that melts the fusible plug and falls under its own weight to be seated on the valve seat. A fusible device with a backflow prevention valve for absorption refrigerators.