JPH0541320Y2 - - Google Patents

Description

[Detailed description of the invention] (Field of industrial application) This invention uses a mixed refrigerant consisting of multiple refrigerants each having a different boiling point, including a refrigerant with a relatively high boiling point for dissolving compressor lubricating oil. Regarding the low-temperature refrigerator used.

(Conventional technology and its problems) Conventionally, as this type of low-temperature refrigerator, for example, Jikkosho
The one disclosed in FIG. 3 of Japanese Patent No. 55-2374 is known. In this low-temperature refrigerator, a separated liquid is added to the mixed refrigerant, which has a boiling point higher than the refrigerant with the highest boiling point in the mixed refrigerant and has a high degree of miscibility or solubility with the compressor lubricating oil used. Ru. This mixed refrigerant is compressed in a compressor in a hot gaseous state and partially condensed in a first condenser stage to form a gas-liquid mixed refrigerant. At this time, almost all of the separated liquid is condensed, and by separating it into gas and liquid, the compressor lubricating oil dissolved in the separated liquid is recovered, and the remaining gas phase is mixed to prevent the compressor lubricating oil from reaching the low temperature range. Separated from refrigerant.

However, in actual operation, the separation of the compressor lubricating oil is not 100%, and it leaks into the low temperature region little by little without being separated. Since good quality lubricating oil has a relatively high pour point, leaked lubricating oil will no longer flow at low temperatures, and will accumulate and cause blockage in piping, especially small-diameter capillary tubes, during long-term continuous operation. There was a problem that pipe clogging occurred.

(Purpose of the invention) Therefore, the purpose of this invention is to provide a low-temperature refrigerator that does not cause pipe clogging even during long-term continuous operation in a refrigeration system that uses a mixed refrigerant in which compressor lubricating oil is dissolved. be.

(Means for Achieving the Object) In order to achieve the above object, the cryogenic refrigerator according to this invention includes a first refrigerant having a relatively high boiling point for dissolving compressor lubricating oil, each having a different boiling point. a compressor for compressing a mixed refrigerant in a high-temperature vapor phase consisting of a plurality of refrigerants; a return passage for introducing the mixed refrigerant into the compressor; and a partial condensation of the mixed refrigerant compressed by the compressor. a condenser that produces a gas-liquid mixed refrigerant containing at least the first refrigerant in a liquid phase; a gas-liquid separator that separates the gas-liquid mixed refrigerant into a gas-phase refrigerant and a liquid-phase refrigerant; The gas phase refrigerant provided on the return flow path and separated by the gas-liquid separator is at least partially condensed by heat exchange with the refrigerant flowing through the return flow path to produce a low-temperature liquid phase or gas-liquid mixed refrigerant. a plurality of heat exchangers that produce a a first throttle flow path that joins the return flow path immediately upstream of a predetermined heat exchanger other than the heat exchanger located therein, and a downstream side on the return flow path from the confluence with the first throttle flow path; The liquid phase refrigerant obtained by partial condensation by the heat exchanger located at a second throttle flow path that joins the flow path; and a third throttle flow path that depressurizes and expands the low-temperature liquid phase refrigerant obtained by a heat exchanger located upstream of the return flow path than the first throttle flow path. a throttle flow path; and a cooler that cools the low-temperature liquid phase refrigerant that has been depressurized and expanded by the third throttle flow path by at least partially evaporating it and introduces it into the upstream end of the return flow path; , a bypass flow in which the liquid phase refrigerant separated from the gas phase refrigerant by the gas-liquid separator joins immediately upstream of at least one of the second throttle channel or the third throttle channel; The bypass flow path is further provided with an opening/closing means for opening and closing the bypass flow path. By having the above-mentioned structural features, the low-temperature refrigerator according to this invention converts the compressor lubricating oil, which has stopped flowing in the low-temperature range, into a relatively high-temperature liquid that has high solubility in the compressor lubricating oil. Can be cleaned with phase refrigerant.

(Embodiment) The drawing is a configuration diagram showing an embodiment of a low temperature refrigerator according to the present invention. In this low-temperature refrigerator, a mixed refrigerant consisting of a plurality of refrigerants each having a different boiling point is used as the refrigerant. Furthermore, as a refrigerant with a relatively high boiling point in the mixed refrigerant, for example, R11, R
A refrigerant having excellent solubility with the compressor lubricating oil, such as No. 12, is used, and the compressor lubricating oil is dissolved in this relatively high boiling point refrigerant, and the refrigerant is applied to the illustrated low-temperature refrigerator.

After the mixed refrigerant in the high temperature vapor phase is compressed by the compressor 1,
It is passed through conduit 2 to condenser 3 where it is partially condensed. The condenser 3 partially condenses the mixed refrigerant, for example by exchanging heat with an air stream sent by a blower 4. Furthermore, an auxiliary condenser may be provided after the condenser 3 to promote condensation by the condenser 3 through heat exchange with the refrigerant flowing through the return passage 5 to the compressor 1.

The gas-liquid mixed refrigerant thus partially condensed is sent through the conduit 6 to the gas-liquid separator 7, where it is separated into a gas-phase refrigerant and a liquid-phase refrigerant. This separated liquid-phase refrigerant has a relatively high boiling point, and includes dissolved compressor lubricating oils such as R11 and R12 described above. Therefore, at this stage, the compressor lubricating oil is separated from the gaseous refrigerant and recovered in a state dissolved in the liquid refrigerant. At least 100
As mentioned above, it is not completely separated, but some amount gets mixed into the gas phase refrigerant, causing pipe clogging in the low temperature range.

The liquid phase refrigerant separated by the gas-liquid separator 7 is depressurized and expanded by the throttle channel 8 consisting of a capillary tube, and is then expanded at the upstream side of the first heat exchanger 9.
It is merged into a return flow path 5 to the compressor 1. The gas phase refrigerant separated by the gas-liquid separator 7 is sent through the conduit 10 to the first heat exchanger 9, where it is passed through the return flow path 5.
It is partially condensed by heat exchange with the refrigerant flowing through the refrigerant, and becomes a gas-liquid mixed refrigerant.

A part of the liquid phase refrigerant obtained in this way is guided to the throttle channel 11 consisting of a capillary tube, is depressurized and expanded there, and joins the return channel 5 on the upstream side of the second heat exchanger 12. be done. The remaining liquid and vapor phase refrigerants are conducted through conduit 13 to second heat exchanger 12 where they are wholly or partially condensed into a low temperature liquid phase or gas-liquid mixture refrigerant. Note that the gas-liquid mixed refrigerant obtained by the first heat exchanger 9 is separated by a gas-liquid separator, and the liquid phase refrigerant is merged into the return flow path 5 via the throttle flow path 11.
It is also possible to adopt a configuration in which the gas phase refrigerant is guided to the second heat exchanger 12.

The low-temperature refrigerant obtained by the second heat exchanger 12 is expanded under reduced pressure by the throttle passage 14 made of a capillary tube, and is sent to the cooler 15, where it is at least partially evaporated to remove the heat of vaporization, resulting in a low temperature. Provides a cooling effect.

The mixed refrigerant thus compressed in the compressor 1 releases heat in a series of condensation stages and is successively partially condensed to achieve an extremely low temperature, and at this extremely low temperature the refrigeration cooling action takes place. It can be done. The refrigerant after cooling in the cooler 15 is returned to the compressor 1 through the return flow path 5.

On the other hand, the separation of the compressor lubricating oil by the gas-liquid separator 7 is not 100% complete, and there is some leakage into the low-temperature region, so this oil does not flow in the low-temperature state and accumulates in the pipes. In this case, the throttle channel 1 consists of a capillary tube with a particularly small diameter.
1 and 14, there is a risk of pipe clogging, and this tendency is most noticeable in the throttle channel 14 in the lowest temperature range, and problems such as poor refrigerant transport efficiency also occur in other piping sections.

Therefore, in this invention, a bypass flow path 16 is provided from the gas-liquid separator 7 to the immediately upstream side of the throttle flow path 14 in the lowest temperature range, and a solenoid valve 1 is provided in this bypass flow path 16.
7 is inserted so that it can be opened and closed freely. By opening the solenoid valve 17, the relatively high temperature liquid refrigerant separated in the gas-liquid separator 7 is throttled into the flow path 14.
The filter is configured so that it can be bypassed and flowed near the inlet of the filter to clean the throttle channel 14.

For example, by opening the solenoid valve 17 for several minutes periodically (every 12 or 24 hours) to clean the compressor lubricating oil that has adhered to the inside of the throttle channel 14, pipe blockage will not occur even during long-term continuous operation. There is no reduction in cooling performance. The temperature rise during that time is 3-5
℃, which is not a practical problem. R11 and R1 separated by gas-liquid separator 7
Liquid phase refrigerants such as No. 2 have excellent solubility in compressor lubricating oil and are highly effective in cleaning compressor lubricating oil.
In addition, the temperature of this liquid phase refrigerant is considerably higher than that near the throttle channel 14, and by opening the solenoid valve 17 and bypassing it, the temperature near the throttle channel 14 can be raised. The cleaning effect can be further enhanced.

In the above embodiment, the bypass flow path 16 is connected to the immediately upstream side of the throttle flow path 14, but it may be connected to the right upstream side of the throttle flow path 11, or it may be connected to both of them to form a solenoid valve. It may also be configured to selectively open. Also, the throttle channels 8, 11, 14
Although an example using a capillary tube has been described, it goes without saying that this invention can also be applied to a case where a throttle valve is used. Further, although the case where the heat exchanger has a two-stage configuration is shown, the present invention can be similarly applied even if the heat exchanger has a multi-stage configuration.

(Effects of the invention) As explained above, according to this invention, in a refrigeration system using a mixed refrigerant in which compressor lubricating oil is dissolved, pipe clogging does not occur even during long-term continuous operation, and the refrigeration efficiency is improved. A low-temperature refrigerator that does not deteriorate can be obtained.

[Brief explanation of the drawing]

The drawing is a configuration diagram showing an embodiment of the low temperature refrigerator according to this invention. 1... Compressor, 3... Condenser, 5... Return path, 7... Gas-liquid separator, 8, 11, 14... Throttle channel, 9, 12... Heat exchanger, 15... Cooler,
16... Bypass flow path, 17... Solenoid valve.

Claims (1)

[Claims for Utility Model Registration] (1) A mixed refrigerant in a high temperature vapor phase consisting of a plurality of refrigerants each having a different boiling point, including a first refrigerant with a relatively high boiling point for dissolving compressor lubricating oil. a compressor for compressing; a return flow path for introducing the mixed refrigerant into the compressor; and a return flow path for partially condensing the mixed refrigerant compressed by the compressor to bring at least the first refrigerant into a liquid phase. a condenser that produces a gas-liquid mixed refrigerant containing the gas-liquid refrigerant; a gas-liquid separator that separates the gas-liquid mixed refrigerant into a gas-phase refrigerant and a liquid-phase refrigerant; a plurality of heat exchangers that at least partially condense the separated gas-phase refrigerant through heat exchange with the refrigerant flowing through the return flow path to produce a low-temperature liquid phase or gas-liquid mixed refrigerant; and the gas-liquid separation. The liquid phase refrigerant separated by the chamber is expanded under reduced pressure, and the expanded liquid phase refrigerant is transferred to a predetermined heat exchanger other than the heat exchanger located on the most upstream side of the return flow path among the heat exchangers. A first throttle channel that joins the return channel immediately upstream; and a heat exchanger located downstream of the junction with the first throttle channel on the return channel. a second throttle flow path that expands the liquid phase refrigerant under reduced pressure and joins the return flow path immediately upstream of a heat exchanger located upstream of the return flow path than the first throttle flow path; a third throttle flow path for depressurizing and expanding a low-temperature liquid phase refrigerant obtained by a heat exchanger located upstream of the return flow path than the first throttle flow path; and by the third throttle flow path. A low-temperature refrigerator comprising: a cooler that cools the low-temperature liquid phase refrigerant that has been expanded under reduced pressure by at least partially evaporating it and introduces it into the upstream end of the return flow path; a bypass flow path in which the liquid phase refrigerant separated from the refrigerant joins immediately upstream of at least one of the second throttle flow path or the third throttle flow path; and opening and closing of this bypass flow path. A low-temperature refrigerator further comprising an opening/closing means for opening and closing the refrigerator. (2) The low temperature refrigerator according to claim 1, wherein the second and third throttle channels are capillary tubes.