JPS6038560A - Two-step compression refrigerator - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a two-stage refrigeration system using a liquid-filled non-generation unit and a liquid cooler, and in particular, to a two-stage refrigeration system using a liquid-filled non-sparking unit and a liquid cooler. This relates to control to prevent liquid backflow to the high-pressure side compressor, which is caused by the loss of load on the liquid cooler when the refrigerant supply is cut off. The refrigerant is compressed in two stages using a high-pressure compressor and a high-pressure side compressor, and because of its high cooling efficiency, it is often applied to large-scale refrigeration equipment.

FIG. 1 is a block diagram showing an example of a conventional two-stage compression refrigeration system, in which l is a low-pressure side compressor constituting a two-stage compressor, and 2 is a low-pressure side compressor 1. An intermediate gas cooler 3 cools the refrigerant gas compressed in the intermediate gas cooler 2, and 3 is a high pressure side compressor that recompresses the gas cooled in the intermediate gas cooler 2. It constitutes a compressor. 4 is a condenser that liquefies the refrigerant gas compressed in the high-pressure side compressor 3, 5 is a liquid cooler that supercools the liquid refrigerant liquefied in the condenser 4, and 6 is a liquid-filled non-sparking device. , 7 is a valve 0- for controlling the refrigerant liquid level of the liquid-filled non-generator.
) switch, 8 is an on-off valve that opens and closes the supply of refrigerant to the evaporator 6, 9 is an expansion valve of the evaporator 6, and 10 is an on-off valve that opens and closes the supply of cooling refrigerant to the liquid cooler 5 and the intermediate gas cooler 2. , 11 are expansion valves for the Nada cooler 5 and the intermediate gas cooler 2. Reference numeral 12 denotes a supply conduit for supplying the refrigerant gas, which has undergone heat exchange with the refrigerant liquid in the liquid cooler 5, to the intermediate gas cooler 2.

In the two-stage compression refrigeration system configured in this way, the refrigerant gas compressed in the low pressure side compressor 1 is cooled in the intermediate gas cooler 2 and then transferred to the high pressure side compressor 3. After being recompressed, it is liquefied in a condenser 4. The refrigerant liquefied in this way is supplied to the liquid cooler 5, and a part of the liquefied refrigerant passes through the on-off valve 10 and expansion valve 11, which are opened and closed in response to the operation of the compressor and a stop signal, and is then liquefied in the liquid cooler 5. Cool the refrigerant. In this way, the refrigerant blown into the liquid cooler 5 exchanges heat with the liquid refrigerant, is compressed into the low pressure side compressor 1 via the conduit 12, and is then cooled in the intermediate gas cooler 2. Ru. The liquid refrigerant cooled in the liquid cooler 5 is then transferred to the on-off valve 8. flooded evaporator 6 via expansion valve 9
supplied to Here, the refrigerant gas that has been gasified by heat exchange with the fuel (not shown) is sucked into the low pressure side compression 1i1.

The liquid level in the evaporator 6 is limited to a certain range in order to achieve the best performance of the evaporator 6 and to prevent liquid from leaking into the compressor. In other words, the liquid level is controlled by the float switch 7.
Accordingly, when the liquid level in the evaporator 6 becomes higher than the set value, the on-off valve 8 is closed, and when the liquid level becomes lower than the set value, the on-off valve 8 is opened.

However, in the two-stage compression refrigeration system with the above configuration, when the liquid level in the evaporator 6 exceeds a set value, the on-off valve 8 closes and the supply of liquid refrigerant to the evaporator 6 is cut off, and the liquid cooler 5
The load on the liquid cooler 5 is removed from the expansion valve 11. Furthermore, there is a problem in that an excessive amount of refrigerant is blown into the intermediate gas cooler 2 and a liquid dock phenomenon occurs in the high-pressure side compressor 3.

[Summary of the invention]

This invention was made to eliminate the above-mentioned drawbacks, and includes a cooling system for the intermediate gas cooler 2 and a liquid cooler 5.
An on-off valve and an expansion valve suitable for each load are provided for each cooling system, and when the on-off valve 8 is closed, the cooling system of the liquid cooler 5 is closed and the liquid is not supplied to the high-pressure side compressor. This is to prevent backlash.

[Example of practical application of invention]

FIGS. 2 and 3 are a block diagram and sequence circuit of main parts showing an embodiment of a two-stage compression refrigeration system according to the present invention, and the same parts as in FIG. 1 are indicated using the same symbols. In the figure, 12 is a supply conduit for supplying the refrigerant gas heat exchanged with the cooling liquid in the liquid cooler 5 to the intermediate gas cooler 2, and 13 is a supply pipe for supplying the cooling refrigerant to the intermediate gas cooler 2. An on-off valve that opens and closes, 14 is an expansion valve of the intermediate gas cooler 2, 15
is the blowing conduit of the expansion valve 14 to the intermediate gas cooler 2.

Further, in FIG. 3, 21 is a compressor operation signal contact for the compressors 1 and 3, and 22 is a float switch contact, which is closed when the liquid level decreases. 23 is a coil of the on-off valve 13, 2
4 is a coil of the on-off valve 8, and 25 is a coil of the on-off valve 10, and when the coils 24 and 25 are energized, the on-off valves 13 and 8 are opened.

In the two-stage compression refrigeration system configured in this way, the refrigerant gas compressed in the low-pressure side compressor 1 is cooled in the intermediate gas cooler 2 and then transferred to the high-pressure side compressor 3. It is recompressed and supplied to the condenser 4 where it is liquefied. Then, this liquefied refrigerant is supplied to the liquid cooler 5, and a part of the liquefied refrigerant is connected to an on-off valve 10 for the liquid cooler 5, which is opened and closed by a signal from a flow switch 7 that controls the liquid level of the evaporator 6. It is cooled by being supplied to the liquid cooler 5 through the expansion valve 11. The refrigerant supplied to the liquid cooler 5 exchanges heat with the liquid refrigerant and then escapes to the intermediate gas cooler 2 through the conduit 12. Also, a portion of the cooling material for the intermediate gas cooler 2 is taken out from the outlet of the condenser 4 and passed through an on-off valve 13 that opens and closes depending on the operation and stop signals of the compressor, an expansion valve 14 of the intermediate gas cooler 2, and a conduit 15. The gas discharged from the low pressure side compressor 1 is cooled by being blown into the intermediate gas cooler 2. The liquid refrigerant cooled in the liquid cooler 5 is then transferred to the on-off valve 8. It is supplied to the flooded evaporator 6 through an expansion valve 9.

Here, the refrigerant that has been gasified through heat exchange with a load (not shown) is blown into the low-pressure side compressor 1.

In addition, the liquid level control of the flooded evaporator 6 is the same as the conventional operation, but when the compressor operation signal contact 21 shown in FIG. Since valve 13 is open, cooling takes place. Furthermore, when the liquid level in the evaporator 6 becomes higher than the high setting liquid level, the contact 22 of the float switch 7 is disconnected, the coils 24 and 25 of the on-off valves 8 and 10 are de-energized, and the on-off valves 8 and 10 are closed. As a result, the refrigerant supply to the evaporator 6 is stopped, and liquid backflow to the low-pressure side compressor 1 is prevented, and liquid backflow to the high-pressure side compressor 3 is also prevented.

In the above embodiment, the case where the float switch is attached to the flooded evaporator 6 has been described, but the present invention is not limited to this, and the float switch may also be attached to the low-pressure receipt. Needless to say, similar effects can be obtained.

〔Effect of the invention〕

As explained above, the two-stage compression refrigeration system according to the present invention is configured so that control suitable for the load side can be performed by dividing the cooling system into intermediate gas cooling and liquid cooling. It has an excellent effect that allows stable operation as a cooling device.

[Brief explanation of drawings]

FIG. 1 is a block diagram of main parts showing an example of a conventional two-stage compression refrigeration system, FIG. 2 is a block diagram of main parts showing an embodiment of a two-stage compression refrigeration system according to the present invention, and FIG. FIG. 3 is a sequence circuit diagram used for controlling the block diagram shown in FIG. 1...Low pressure side compressor, 2...Intermediate gas cooler, 3...
... High pressure side compressor, 4... Condenser, 5... Liquid cooler, 6... Full liquid type evaporator, 7... Float switch,
8... Opening/closing valve, 9... Expansion valve, 10... Opening/closing valve,
DESCRIPTION OF SYMBOLS 11... Expansion valve, 12... Conduit, 13... Open/close valve, 14... Expansion valve, 15... Conduit, 21... Compressor operation signal contact, 22... Float switch contact ,2
3, 24, 25°°° coils. Note that the same reference numerals in the figures indicate the same or equivalent parts. Warehouse 1 B O 2 Heir 10/l No. 3m Procedural amendment (voluntary) Commissioner of the Japan Patent Office 1, Indication of case Japanese Patent Application No. 148491/1982 2, Name of the invention 2-stage compression refrigeration device 3, Name of the person making the amendment Name (601) Mitsubishi Electric Co., Ltd. Representative Hitoshi Katayama 4, Agent /' 7/- 5, Subject of amendment (1) Detailed explanation of the invention in the specification column 6 Contents of amendment (1) Specification On page 3, line 2 of the book, the phrase ``plunge cooler'' has been corrected to ``liquid cooler.'' (2) On page 4, line 15, the phrase "liquid dock phenomenon" is corrected to "liquid back phenomenon." (3) On the 17th line of No. 7, the phrase “low pressure receipt” is replaced with “
"Low pressure receiver".

Claims (1)

[Claims] (1) The refrigerant is divided into two parts by the low-pressure side compressor and the high-pressure side compressor.
In a two-stage compression refrigeration system that performs stage compression, there is a liquid-filled non-generator, an on-off valve that opens and closes by opening and closing a float switch provided on the liquid-filled non-generator, and a liquid cooling system that supercools the refrigerant. an on-off valve and an expansion valve that supply cooling refrigerant to the gas cooler; and an on-off valve and an expansion valve that are provided in parallel with the on-off valve and the expansion valve and supply the cooling refrigerant to the intermediate gas cooler. A two-stage compression refrigeration device characterized by: