JPH02238257A - Liquid return preventing device for full-liquid type evaporator - Google Patents

Abstract

PURPOSE:To prevent return of liquid by attaching a level tank to a liquid reservoir, providing a liquid surface level switch set at its lower limit position to a position slightly lower than a normal liquid surface level in the tank, and cooperating the operation of the switch with a compressor stop switch. CONSTITUTION:A level tank 8 attached to a full-liquid type evaporator 9 has the same liquid surface level as that of the evaporator 9. A liquid surface level detector 10 senses variation in a liquid level with the normal liquid surface of the evaporator 9 as a reference liquid surface, and controls liquid refrigerant supplying amount from a liquid reservoir 4 in cooperation with an expansion valve 7. In a liquid return preventing device, when liquid refrigerant is mixed with refrigerant discharged from the evaporator 9 and moved into a suction tube of a compressor 1, the liquid surface of the reservoir 4 is lowered in response to the moving amount since the liquid surface of the evaporator 9 is controlled to be constant. A liquid surface drop similarly occurs at the side of a level tank 5 communicating with the reservoir 4, and when it reaches a lower limit position set therein, a liquid surface switch 6 senses it, a compressor stop switch is operated to stop the compressor 1 before the liquid refrigerant is sucked into the compressor 1 to prevent return of the liquid.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a device for preventing liquid refrigerant from returning to a compressor in a flooded evaporator. This relates to a liquid return prevention device for a flooded evaporator that detects the drop in temperature and stops compressor operation to prevent wet operation of the refrigerator. (Prior Art) As shown in FIG. 2, a refrigeration system equipped with a flooded evaporator is such that gas refrigerant discharged from a compressor (11) is
) After the oil is removed in the oil separator (2) attached to the oil separator (2), it is condensed and liquefied in the condenser (3), temporarily stored in the liquid receiver (4), and then filled with liquid through the expansion valve (7). Type evaporator (
9). At this time, only the liquid refrigerant flows into the evaporator (9), and the liquid level is detected by the liquid level detector α in the level tank (8) attached to the evaporator (9), and in response to this. It is always controlled to be constant by the expansion valve (7).

In this way, the flooded evaporator (9) has excellent heat exchange because the refrigerant flowing inside it is liquid, and can obtain high refrigeration output. Since the liquid level control cannot control the superheat degree, the evaporator (9
) may not be completely gasified and may be discharged as a liquid refrigerant. This state is called wet operation, and if left as is, the liquid refrigerant will flow into the compressor (1).
This results in a so-called liquid return condition, which causes a fatal failure of the compressor (1). Therefore, in order to prevent the above-mentioned liquid return, normally a liquid separator, liquid-gas heat exchanger, etc. Liquid refrigerant in the suction pipe is removed.

(Problem B to be solved by the invention) However, even if a liquid separator or liquid-gas heat exchanger is installed in the piping returning to the compressor as described above, there is no way to know if these devices break down. , there remains a risk of liquid refrigerant returning to the compressor.

In order to deal with the above-mentioned situation, the present invention detects when there is a risk of liquid returning to the compressor in a flooded evaporator, stops the compressor in advance, and prevents liquid returning. The purpose is to

(Means for Solving the Problems) That is, a feature of the present invention that meets the above problems is a refrigeration system equipped with a flooded evaporator equipped with a compressor, a condenser, a liquid receiver, an expansion valve, and a level tank. In this method, a level tank is attached to the liquid receiver, a liquid level switch is provided on the level tank with a lower limit position slightly lower than the normal liquid level, and the operation of the liquid level switch is linked to a compressor stop switch. It's about forcing.

Further, the invention of claim 2 resides in that, in the above-mentioned device, a switch for issuing an alarm is further provided at a position above the coffin from the lower limit position of the level tank.

(Function) Also in the refrigeration system equipped with the liquid return device for the flooded evaporator according to the present invention, the expansion valve control is liquid level control, and therefore the liquid level in the evaporator is kept constant as in the conventional case. Also, during normal operation, liquid refrigerant mainly exists only in the pipe between the receiver and the evaporator. However, when the liquid refrigerant leaves the evaporator and moves into the compressor suction pipe, the liquid level in the receiver decreases according to the amount of movement, since the liquid level in the evaporator is kept constant as described above. .

Since the liquid receiver of the present invention is equipped with a level tank and a liquid level switch whose lower limit position is slightly lower than the normal liquid level, the liquid refrigerant does not move into the compressor suction pipe as described above. When the liquid level in the level tank reaches the cent position, the liquid level switch is activated, and in conjunction with this, the compressor stop switch is activated to stop the compressor before the liquid returns.

Furthermore, in the invention set forth in claim 2, when the liquid refrigerant moves from the evaporator to the compressor suction pipe, an alarm is first issued and then the compressor is stopped. Make it easier to deal with. In this way, even if a failure occurs in the level tank or the like of the evaporator, the status of liquid returning to the compressor can be accurately grasped, the compressor can be stopped, and safe operation of the equipment can be ensured.

(Example) Further, a liquid return prevention device for a flooded evaporator according to the present invention will be described based on the drawings.

FIG. 1 shows an example of a refrigeration system equipped with a liquid return prevention device according to the present invention.

In the figure, during normal operation, the gas refrigerant discharged from the compressor (1) has its oil removed by the oil separator (2) attached to the compressor (11), is condensed and liquefied in the condenser (3), and then After being stored in the liquid receiver (4), the gas refrigerant is separated through the expansion valve (7) and only the liquid refrigerant flows into the flooded evaporator (9), where it is mixed with the heat medium on the Icheon side. It exchanges heat and evaporates, becoming a gas refrigerant and being sucked into the compressor (1), forming a circulation cycle.

In the figure, {5} is a level tank attached to the liquid receiver (4) as a feature of the present invention. The level tank (5) has a known configuration, is connected to the liquid receiver (4) by piping to maintain the same liquid level, and has a liquid level switch (6) inserted inside. . The liquid level switch (6) sets the lower limit position to a position slightly lower than the liquid level during normal operation, and when the liquid level falls to the lower limit position, the compressor (1) is stopped in conjunction with this. , the compressor stop switch (
(not shown). Here, the above lower limit position is set as appropriate, but
The lower limit position of the liquid receiver (4) is determined and set within that range, taking into account at least the amount of liquid refrigerant that does not affect the compressor (11) even after leaving the evaporator (9). It is something.

On the other hand, (8) is a level tank attached to the flooded evaporator (9), which has the same liquid level as the evaporator (9) and has a liquid level detector inserted inside. The liquid level detector α0 senses changes in the liquid level with the normal liquid level of the flooded evaporator {9} as a reference liquid level, and also detects the liquid receiver (4) in conjunction with the expansion valve (7). ) to maintain a constant liquid level in the evaporator (9).

The liquid return prevention device configured as described above firstly assumes that liquid refrigerant mixes with the refrigerant discharged from the flooded evaporator (9) and moves into the suction pipe of the compressor +11. Since the liquid level in the evaporator (9) is controlled to be constant, the liquid level in the receiver (4) decreases in accordance with the amount of movement. At the same time, this drop in the liquid level is caused by the level tank (4) communicating with the liquid receiver (4).
The same thing occurs on the 5) side, and when the lower limit position is reached, the liquid level switch (6) senses this and the compressor stop switch is activated, causing the liquid refrigerant to be sucked into the compression @ (1). The compressor (1) is stopped beforehand to prevent liquid return.

Furthermore, it is also possible to provide an alarm issuing switch (not shown) above the lower limit position of the level tank (5).

This is the configuration described in claim 2, that is, in addition to a liquid level switch that operates at the lower limit position as the liquid level decreases, a switch that similarly operates by sensing the liquid level is provided above the coffin. By interlocking the switch with an external alarm, when the liquid refrigerant moves into the suction pipe of the compressor (11), the compression 11!1 (1) will be stopped before it stops.
It becomes possible to give advance notice of the stoppage, which not only prevents the liquid from returning, but also allows the operator to take appropriate measures afterwards.

In addition to the above embodiment, in the refrigeration system configured as described above, a liquid separator, a liquid-gas heat exchanger, etc. are installed in the piping from the flooded evaporator (9) to the compressor (1) as in the past. There is no problem with the arrangement, and in this case, the capacity of the device can be made small, and all possible precautions can be taken against liquid return.

(Effects of the Invention) As described above, the present invention provides a refrigeration system equipped with a flooded evaporator, in which a liquid level switch for detecting a drop in the liquid level is attached to the liquid receiver, and the flow from the flooded evaporator to the compressor is provided. If there is liquid refrigerant trying to return, this is immediately sensed by a drop in the liquid level in the liquid receiver, and the compressor is stopped before liquid returns. In addition to eliminating the need to install equipment such as liquid separators and liquid-gas heat exchangers,
Reliably prevent liquid return.

Furthermore, even if devices such as the liquid separator are installed as a precaution, the capacity of the devices can be reduced, and even if these devices break down, liquid return can be reliably prevented.

Furthermore, if a warning switch is provided as described in claim 2, it is possible to notify the operator of liquid refrigerant outflow due to wet operation, etc., immediately before the compressor is stopped, thereby making it possible to manually stop the compressor. On the other hand, even if you leave the compressor as it is and stop the compressor, the cause of the stoppage is obvious and you can take appropriate measures without inspecting unnecessary parts. As described above, the liquid return prevention device for a liquid flooded evaporator according to the present invention can always protect the compressor from liquid return, and thereby ensure the safe operation of the entire refrigeration system.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing a refrigeration cycle of a refrigeration system equipped with a liquid return prevention device for a flooded evaporator according to the present invention, and FIG. 2 is a schematic diagram showing a refrigeration cycle of a refrigeration system equipped with a conventional flooded evaporator. It is a schematic diagram showing a refrigeration cycle. (1)...Compressor, (3)...Condenser, (4)...
...Liquid receiver, (5)...Level tank, (6)...
・Liquid level switch, (7)...expansion valve, (8)...
Level tank, (9)... flooded evaporator.

Claims (1)

[Claims] 1. A flooded evaporator (9) equipped with a compressor (1), a condenser (3), a liquid receiver (4), an expansion valve (7) and a level tank (8). In the refrigeration apparatus equipped with the liquid receiver (4)
A level tank (5) is attached to the level tank (5).
A liquid level switch (6) with a lower limit position set at a position slightly lower than the normal liquid level is provided at the liquid level switch (6).
1. A liquid return prevention device for a flooded evaporator, characterized in that the operation of the compressor (1) is linked to a stop switch of the compressor (1). 2. The device according to claim 1, wherein the level tank (5)
A liquid return prevention device for a flooded evaporator, characterized in that a switch for issuing an alarm is further provided at a position slightly above the lower limit position.