WO2016103296A1

WO2016103296A1 - Refrigeration device

Info

Publication number: WO2016103296A1
Application number: PCT/JP2014/006470
Authority: WO
Inventors: 良祐綿貫; 徹中山; 英史大森; 裕山中
Original assignee: 日揮株式会社
Priority date: 2014-12-25
Filing date: 2014-12-25
Publication date: 2016-06-30

Abstract

Provided is a refrigeration device that efficiently employs an ejector in a refrigeration cycle. A first-stage ejector 41a provided in a refrigeration device sucks a refrigerant gas by the ejection of a high-pressure refrigerant liquid obtained by condensing a high-pressure refrigerant gas emitted from a compressor 20, and increases the pressure of a mixed fluid thereof. A first-stage heat exchanger 34a cools a fluid to be cooled by exchanging heat with the mixed fluid the pressure of which has been increased by the first-stage ejector 41a. A first-stage gas-liquid separator 33a separates a liquid accompanying the refrigerant gas generated by the first-stage heat exchanger 34a, and sends the liquid to the compressor 20. A next-stage heat exchanger 34b cools the fluid to be cooled by exchanging heat with a refrigerant obtained by expanding, with an expander 36b, the refrigerant liquid that did not vaporize in the first-stage heat exchanger 34a. The refrigeration device also includes a flow path 501 that supplies a refrigerant gas generated by the next-stage heat exchanger 34b to a suction opening 413 of the first-stage ejector 41a.

Description

Refrigeration equipment

The present invention relates to a refrigeration apparatus for cooling a fluid to be cooled such as natural gas.

The production process of liquefied natural gas is a process of performing pretreatment such as acid gas removal and moisture removal on natural gas, followed by precooling to, for example, around −40 ° C. with a precooling refrigerant, and then heavy gas from natural gas. After removing the gas, it is provided with a step of cooling to −160 ° C. to −160 ° C. with the main refrigerant and liquefying. A refrigerant mainly composed of propane is used as the precooling refrigerant, and a mixed refrigerant obtained by mixing methane, ethane, propane and nitrogen is used as the main refrigerant.

These refrigerants are circulated and used in a vapor compression refrigeration cycle. In the refrigeration cycle, the refrigerant is compressed by a compressor in a gaseous state, and then cooled and liquefied by a condenser, and the liquefied refrigerant having a high pressure is reduced in pressure by an expansion valve or the like. The low-temperature refrigerant is vaporized by heat exchange with natural gas and becomes a gas again. The precooling refrigerant is also used to cool the main refrigerant compressed by the compressor, and the main refrigerant is cooled by the precooling refrigerant and then exchanges heat with natural gas.

When focusing on a general refrigeration cycle, for example, Patent Document 1 proposes a technique for improving the efficiency of a refrigeration cycle by replacing an expansion valve provided in the refrigeration cycle with an ejector. However, the refrigeration cycle described in Patent Document 1 is applied to relatively small devices such as air conditioners such as air conditioners and refrigerators for showcases. Therefore, there is no description of an efficient utilization method when an ejector is provided in a refrigeration cycle of a large plant as in a natural gas liquefaction system.

Here, Patent Document 2 discloses a technique for reducing the outlet pressure of a refrigeration compressor to an external pressure or lower using an ejector in order to reduce power when starting a refrigeration compressor provided in a natural gas refrigeration cycle. Are listed. Patent Document 3 describes a technique in which natural gas cooled and liquefied by a heat exchanger is decompressed and expanded into a rectifying column by an ejector to separate nitrogen contained in the liquefied natural gas.
However, the ejector described in the cited document 2 ends its use after starting the refrigeration compressor, and the ejector described in the cited document 3 is a device on the cooled fluid side, both of which are parts of the refrigeration cycle. It is not an ejector constituting the part.

JP 2009-299911 A Japanese Patent No. 4976426 U.S. Pat. No. 4,112,700

The present invention has been made under such a background, and is to provide a refrigeration apparatus that efficiently uses an ejector in a refrigeration cycle.

The refrigeration apparatus according to the first invention corresponds to the embodiment described in FIGS. Hereinafter, in the description of the means for solving the problems, the reference numerals used in these figures are written together as the constituent elements.
The refrigeration apparatus of the present invention includes a compressor (20) that compresses refrigerant gas,
A high-pressure refrigerant liquid obtained by condensing the high-pressure refrigerant gas discharged from the compressor is injected, and a suction port for sucking the refrigerant gas by the injection of the high-pressure refrigerant liquid is injected from the nozzle. First-stage ejectors (41a in FIG. 2, 41a and 41d in FIG. 4, 41d in FIG. 5, 41g in FIG. 6) for increasing the pressure of the mixed fluid of the high-pressure refrigerant liquid and the refrigerant gas sucked from the suction port,
The first-stage heat exchanger (34a in FIG. 2, FIG. 4) is supplied with the mixed fluid whose pressure has been increased by the first-stage ejector and heat-exchanged between the mixed fluid and the fluid to be cooled to cool the fluid to be cooled. 34a and 35a, 35a of FIGS. 5 and 6, and
The refrigerant gas generated by heat exchange in the first stage heat exchanger and the liquid accompanying it are gas-liquid separated, and the separated refrigerant gas is sent to the compressor (FIG. 2, 4, 5 and 6 33a),
The refrigerant obtained by expanding the refrigerant liquid that has not been vaporized in the first-stage heat exchanger by the expansion section (36b in FIG. 2, 41b and 41e in FIG. 4, 37b in FIG. 5, and 39 in FIG. 6) is supplied. Then, heat exchange is performed between the refrigerant and the fluid to be cooled to cool the fluid to be cooled (34b in FIG. 2, 34b and 35b in FIG. 4, 35b in FIG. 5, FIG. 6). 38) and
A flow path (501 in FIG. 2, 501a, 501d in FIG. 4, 501a, 501d, FIG. 4) supplies the refrigerant gas generated by heat exchange in the next-stage heat exchanger and the liquid accompanying the refrigerant gas to the suction port of the first-stage ejector. 5 501d and FIG. 6 501j).
Moreover, 2nd invention is corresponded to embodiment shown in FIG. 4, The said expansion | swelling part is equipped with the nozzle in which a high pressure refrigerant | coolant liquid is injected, and the suction port which attracts | sucks refrigerant gas by injection of the said high pressure refrigerant | coolant liquid, It is a next-stage ejector (41b, 41e in FIG. 4) that pressurizes the mixed fluid of the high-pressure refrigerant liquid ejected from the nozzle and the refrigerant gas sucked from the suction port.

The third invention corresponds to the embodiment described in FIGS. 2, 4, and 5, and gas-liquid separation is performed on the refrigerant gas generated by heat exchange in the subsequent heat exchanger and the liquid accompanying the refrigerant gas, A next-stage gas-liquid separator (33b in FIGS. 2, 4, and 5) in which the separated refrigerant gas is sent to the compressor;
A flow path (502 in FIG. 2, 502a in FIG. 4) for supplying the refrigerant gas generated by heat exchange in the next-stage heat exchanger and the liquid accompanying the refrigerant gas to the next-stage gas-liquid separator. 502d, 502d) of FIG.
The refrigerant gas generated by heat exchange in the next-stage heat exchanger and the liquid accompanying the refrigerant gas are supplied separately to the suction port of the first-stage ejector and the gas-liquid separator in the next stage. It is configured.
4th invention is corresponded to embodiment shown in FIG. 4, and the expansion | swelling part which is a structural requirement of the freezing apparatus of 1st invention is an ejector (41b, 41e) of the next stage,
The first stage ejector, the first stage heat exchanger, the second stage ejector, and the second stage heat exchanger, which are constituent requirements of the refrigeration apparatus of the third invention, are used to cool the first cooled fluid. A first set (41a, 34a, 41b, 34b) and a second set (41d, 35a, 41e, 35b) for cooling the second cooled fluid;
The high-pressure refrigerant liquid obtained by condensing the high-pressure refrigerant gas discharged from the compressor is provided at each nozzle of the first-stage ejector (41a) of the first group and the first-stage ejector (41d) of the second group. Is supplied in a diversion,
The first-stage gas-liquid separator (33a) is common to the first group and the second group, and the next-stage gas-liquid separator (33b) is the first group and the second group. It is characterized by being common to.

5th invention is corresponded to embodiment shown in FIG. 5, the high pressure refrigerant | coolant liquid obtained by condensing the high pressure refrigerant | coolant gas discharged from the said compressor (20) is shunted and supplied, and high pressure refrigerant | coolant liquid is supplied. And a suction port that sucks the refrigerant gas by jetting the high-pressure refrigerant liquid, and pressurizes the fluid mixture of the high-pressure refrigerant liquid jetted from the nozzle and the refrigerant gas sucked from the suction port Two first stage ejectors (41a, 41d) are provided in parallel,
When the first-stage ejector on one side is called the first first-stage ejector (41a) and the first-stage ejector on the other side is called the second first-stage ejector (41d),
The mixed fluid pressurized by the first first-stage ejector is supplied, heat exchange is performed between the mixed fluid and the fluid to be cooled to cool the fluid to be cooled, and the refrigerant generated by heat exchange. In the first first-stage heat exchanger (34a), which is the first-stage heat exchanger in which the gas and the liquid accompanying it are supplied to the first-stage gas-liquid separator (33a), and the second first-stage ejector Providing a second first-stage heat exchanger (35a), which is a first-stage heat exchanger to which the pressurized mixed fluid is supplied,
After the first first-stage heat exchanger, the first next-stage expansion section (the ejector 41b in FIG. 5), the first next-stage heat exchanger (34b), and the next-stage gas-liquid separator (33b) ), And the second subsequent stage expansion section (37b) and the second next stage heat exchanger (35b) are provided after the second first stage heat exchanger,
The refrigerant liquid that has not been vaporized in the first first-stage heat exchanger is supplied as a high-pressure refrigerant to the first next-stage heat exchanger via the first next-stage expansion section, and the second first-stage heat exchanger is supplied. The refrigerant liquid that has not been vaporized in the heat exchanger is supplied to the second next-stage heat exchanger as a high-pressure refrigerant through the second next-stage expansion section,
A flow path for supplying the refrigerant gas heat-exchanged in the second next-stage heat exchanger and the liquid accompanying the refrigerant gas to the suction port of the first first-stage ejector and the next-stage gas-liquid separator. (501g, 502d)
The first first-stage heat exchanger and the first next-stage heat exchanger are for cooling the first cooled fluid, and the second first-stage heat exchanger and the second next-stage heat exchanger The stage heat exchanger is provided for cooling the second cooled fluid.
The sixth invention corresponds to the embodiment shown in FIG. 5, and the refrigerant gas exchanged with the heat exchanger (35b) in the second next stage and the liquid accompanying the refrigerant gas are supplied to the first first stage. In addition to the suction port of the ejector and the flow channel (501g, 502d) for supplying to the next-stage gas-liquid separator, the flow channel (501d) for supplying to the suction port of the second first-stage ejector (41d) It is provided.

The seventh invention corresponds to the embodiment described in FIGS. 4 and 5, and natural gas is precooled with a precooling refrigerant, then main cooled with the main refrigerant, and after the main cooling after the main cooling is compressed, the precooling is performed. A refrigeration system used in a natural gas liquefaction system cooled by a refrigerant for use,
The high-pressure refrigerant is a precooling refrigerant,
The first cooled fluid and the second cooled fluid are natural gas and main refrigerant, respectively.

The eighth invention corresponds to the embodiment shown in FIG. 6 and is discharged from the compressor (20) to the first stage expansion valve (37a) provided in parallel with the first stage ejector (41g). The high-pressure refrigerant liquid obtained by condensing the high-pressure refrigerant gas is divided and supplied, and the refrigerant obtained by expanding the high-pressure refrigerant liquid is supplied to the first-stage heat exchanger (35a),
A second-stage heat exchanger (38) in a separate system to which a refrigerant to be supplied to the next-stage heat exchanger (35b) is branched and supplied from the latter stage of the first-stage heat exchanger;
A flow path (501j) for supplying the refrigerant gas generated by heat exchange in the next-stage heat exchanger (38) of the different system and the liquid accompanying the refrigerant gas to the suction port of the first-stage ejector. ,
The heat exchanger (38) in the next stage of the separate system is provided with the refrigerant liquid that has not been vaporized in the heat exchanger (35a) in the first stage on the inlet side of the heat exchanger (38) in the next stage of the separate system. The refrigerant obtained by being expanded by the expanded portion (39) is supplied, heat is exchanged between the refrigerant and the fluid to be cooled to cool the fluid to be cooled, and the fluid to be cooled is The first stage heat exchanger is different from the cooled fluid cooled by the next stage heat exchanger.
6 shows that the lower heat exchanger (35a) of the two upper and lower heat exchanger systems is used as the first stage heat exchanger, and the subsequent stage is placed after the first stage heat exchanger (35a). This is an embodiment in which a heat exchanger (35b) and a heat exchanger (38) of the next stage of another system are provided in parallel.
However, in the eighth invention, the upper stage heat exchanger (34a) is used as the first stage heat exchanger, the first stage ejector is provided on the inlet side of the first stage heat exchanger (34a), A stage heat exchanger (34b) and a next stage heat exchanger (38) of another system may be provided in parallel.

The present invention includes a first-stage heat exchanger and a second-stage heat exchanger that cool a fluid to be cooled using a refrigerant liquid and are connected in series to each other via an expansion unit, and are generated in each heat exchanger. A refrigeration cycle is provided in which a refrigerant gas is compressed by a compressor to obtain a high-pressure refrigerant liquid. When the temperature is lowered by adiabatic expansion of the high-pressure refrigerant liquid, pressure is increased by sucking a part of the refrigerant gas generated in the heat exchanger at the next stage using an ejector. For this reason, it is possible to reduce the supply amount of refrigerant gas generated in the next-stage heat exchanger with relatively low pressure to the compressor, reduce the load on the compressor, and realize an efficient refrigeration cycle. it can.

It is a schematic block diagram of the natural gas liquefaction system. It is a block diagram of the freezing apparatus which concerns on embodiment of this invention provided in the said liquefaction system. It is a vertical side view of the ejector provided in the freezing apparatus. It is a block diagram of the freezing apparatus which concerns on 2nd Embodiment. It is a block diagram of the freezing apparatus which concerns on 3rd Embodiment. It is a block diagram of the freezing apparatus which concerns on 4th Embodiment. It is a block diagram of the conventional freezing apparatus.

The liquefaction system of the natural gas (LNG: Liquefied Natural Gas) provided with the freezing apparatus which concerns on this invention is demonstrated.
First, a schematic configuration of the liquefaction system will be described with reference to FIG.

If it demonstrates along the order which processes natural gas (henceforth "NG"), LNG manufacturing equipment will remove the acid gas removal part 101 which removes the acid gas in NG, and the water | moisture content contained in NG. The water removal unit 102 and the NG that has been subjected to the pretreatment for removing the acid gas and water are precooled and cooled to an intermediate temperature in the range of about −20 ° C. to −70 ° C., for example, −35 ° C. to −39 ° C. The precooling heat exchange unit 103 and the gas-liquid mixed gas cooled to an intermediate temperature are sent to a heavy component removal unit (not shown) to remove heavy components (ethane and heavier components) having 2 or more carbon atoms. Thereafter, LNG containing methane as a main component and containing a small amount of ethane, propane, and butane is cooled to −150 ° C. to −160 ° C. to be liquefied to provide liquefaction unit 104 for obtaining LNG as liquefied gas.
Here, the thick white arrows shown in FIG. 1 indicate the flow of the raw material NG or the product LNG.

The precooling heat exchange unit 103 precools the pretreated NG using, for example, propane which is a precooling refrigerant. The precooling refrigerant is also used for cooling the main refrigerant used in the liquefaction unit 104 at the subsequent stage. Hereinafter, the cooling of the main refrigerant by the precooling refrigerant is referred to as “auxiliary cooling”. In FIG. 1, the flow of propane is indicated by a thin arrow indicated with “C3”, while the flow of the main refrigerant is indicated by an hatched arrow indicated with “MR (MixederRefrigerant)”.

Further, as shown in FIG. 1, the precooling heat exchanging unit 103 and the auxiliary heat exchanging unit 105 for cooling the main refrigerant are preliminarily used for precooling NG and precooling the main refrigerant (MR). The 1st compression part 2a which compresses the refrigerant (C3) for operation is provided. On the other hand, the liquefaction unit 104 includes a second compression unit 2b that compresses the main refrigerant used for liquefaction of NG. Each

compressor

2a, 2b is provided with a plurality of compressors in parallel and in series according to the amount of precooling refrigerant or main refrigerant processed, the pressure difference between the suction side and the discharge side, and the like.

The refrigeration apparatus of this example is configured as a refrigeration cycle of a precooling refrigerant used in the precooling heat exchanging unit 103 and the auxiliary heat exchanging unit 105 constituting the liquefaction system.
Before describing the specific configuration of the refrigeration apparatus, an example of a conventional refrigeration apparatus will be described with reference to FIG.

In the conventional refrigeration apparatus, the precooling refrigerant gas (high-pressure refrigerant gas) that has been pressurized by the compressor 20 constituting the first compressor 2a is cooled and condensed by AFC (AirＦＣFin Cooler) 31a, 31b. The liquid receiver 32 retains the precooling refrigerant liquid (high-pressure refrigerant liquid). The precooling refrigerant (liquid) is supercooled by the AFC 31c, and then precooled heat exchangers 34a to 34d provided on the precooling heat exchange unit 103 side, and an auxiliary provided on the auxiliary heat exchange unit 105 side. The heat exchangers 35a to 35d are supplied separately. The compressor 20 may be gas turbine driven, steam driven, or motor driven.

AFC

31a, 31b, and 31c may be water-cooled heat exchangers.

The precooling heat exchangers 34a to 34d of the precooling heat exchanging section 103 flow NG as a fluid to be cooled to the tube side, and flow a precooling refrigerant to the shell side to perform precooling of NG. The tubes and shells of the precooling heat exchangers 34a to 34d are connected in series with the precooling heat exchanger 34a as the most upstream stage (first stage) and the precooling heat exchanger 34d as the most downstream stage (fourth stage). In these precooling heat exchangers 34a to 34d, NG flows in order from the first stage precooling heat exchanger 34a toward the fourth stage precooling heat exchanger 34d. For convenience of illustration, the description of NG piping connecting the precooling heat exchangers 34a to 34d is omitted (the same applies to FIGS. 2, 4 to 6).

The precooling refrigerant (liquid) supercooled by the AFC 31c is adiabatically expanded by the expansion valve 36a provided on the inlet side of the first stage precooling heat exchanger 34a, and the precooling heat exchange is performed while the temperature is further lowered. Is supplied to the vessel 34a. In the precooling heat exchanger 34a, heat exchange between the precooling refrigerant and NG is performed, and NG is cooled. In the shell of the precooling heat exchanger 34a, gas-liquid separation between the liquid of the precooling refrigerant generated by adiabatic expansion in the expansion valve 36a and heat exchange with NG and the liquid is performed. The gas is extracted from the pre-cooling heat exchanger 34a, and then the accompanying liquid is removed by the knockout drum 33a, and then returned to the high-pressure side suction port of the compressor 20. On the other hand, the liquid in the precooling heat exchanger 34a is extracted toward the second stage precooling heat exchanger 34b. For example, a demister is provided in the knockout drum 33a.

Similarly to the first stage precooling heat exchanger 34a described above, expansion valves 36b to 36d are provided on the inlet side of the second and subsequent stage precooling heat exchangers 34b to 34d, respectively, so that the precooling heat on the upstream stage side is provided. The precooling refrigerant (liquid) supplied from the exchangers 34a to 34c is adiabatically expanded to lower its temperature and then supplied to the downstream precooling heat exchangers 34b to 34d. As a result, the temperature of the precooling refrigerant supplied to the precooling heat exchangers 34a to 34d gradually decreases from the upstream stage to the downstream stage.

As the temperature of the precooling refrigerant decreases, the temperature of the NG cooled by the precooling heat exchangers 34a to 34d gradually decreases, and from the fourth stage precooling heat exchanger 34d, for example, from -35 ° C to -39. NG in the gas-liquid mixed state cooled to 0 ° C. is extracted and supplied to the liquefaction unit 104 in the subsequent stage.
The gas generated in the second and subsequent precooling heat exchangers 34b to 34d also corresponds to the pressure of the knockout drums 33b to 33d after the accompanying liquid is removed from the knockout drums 33b to 33d. It is returned to the suction port of the compressor 20.

Here, the precooling heat exchangers 34a to 34d are provided with liquid level gauges 341a to 341d for detecting the height position (liquid level) of the liquid in the shell. The expansion valves 36a to 36d provided on the inlet side of the respective precooling heat exchangers 34a to 34d are detected by liquid level gauges 341a to 341d provided on the downstream side of the precooling heat exchangers 34a to 34d. The amount of precooling refrigerant passing through the expansion valves 36a to 36d is increased or decreased based on the liquid level.

That is, when the liquid level in each of the precooling heat exchangers 34a to 34d is lower than the target value, the opening of the expansion valves 36a to 36d is increased to increase the supply amount of the precooling refrigerant, while the liquid level is increased. When the level is higher than the target value, control is performed to reduce the supply amount of the precooling refrigerant by reducing the opening degree of the expansion valves 36a to 36d.
The number of stages of the precooling heat exchangers 34a to 34d may be increased or decreased as necessary. A plurality of heat exchanger systems in which these precooling heat exchangers 34a to 34d are connected in series are provided in parallel. Also good.

The configuration of the precooling heat exchangers 34a to 34d provided in the precooling heat exchange unit 103 has been described above, but the configuration of the auxiliary heat exchangers 35a to 35d provided on the auxiliary heat exchange unit 105 side is almost the same. It has become.
That is, the auxiliary heat exchangers 35a to 35d flow the main refrigerant (MR), which is a fluid to be cooled, to the tube side, and flow the precooling refrigerant to the shell side to perform preliminary cooling of the main refrigerant. The tubes and shells 35a to 35d are connected in series in this order. Further, the description of the main refrigerant piping connecting between the auxiliary heat exchangers 35a to 35d is omitted, which is the same as in the case of the precooling heat exchangers 34a to 34d.

Expansion valves 37a to 37d are provided on the inlet sides of the auxiliary heat exchangers 35a to 35d, respectively, so that the precooling refrigerant (liquid) supplied from the upstream side is adiabatically expanded to lower its temperature. Is supplied to each of the auxiliary heat exchangers 35a to 35d to cool the main refrigerant. Also in these auxiliary heat exchangers 35a to 35d, as the temperature of the precooling refrigerant decreases, the temperature of the main refrigerant gradually decreases. For example, the main refrigerant cooled to −35 ° C. to −39 ° C. is supplied to the liquefaction unit 104. Is done.

Further, the gas generated in each of the auxiliary heat exchangers 35a to 35d is introduced into the aforementioned knockout drums 33a to 33d in accordance with the pressure, and the accompanying liquid is removed, and then the compressor corresponding to each pressure is removed. 20 and the flow rate adjustment by the expansion valves 37a to 37d is performed based on the liquid level detected by the liquid level gauges 351a to 351d provided in the auxiliary heat exchangers 35a to 35d. This is the same as the precooling heat exchangers 34a to 34d on the precooling heat exchanging unit 103 side.
Further, the number of stages of the auxiliary heat exchangers 35a to 35d may be increased or decreased as necessary, and a plurality of heat exchanger systems in which the auxiliary heat exchangers 35a to 35d are connected in series are connected in parallel. It may be provided.

As described above with reference to FIG. 7, the refrigeration apparatus includes the precooling heat exchange unit 103 in which the precooling refrigerant flows through the path of “compressor 20 → AFC 31a to 31c → precooling heat exchanger 34a to 34d → compressor 20”. And a refrigeration cycle on the auxiliary heat exchange section 105 side through which the precooling refrigerant flows through a path of “compressor 20 → AFC 31a to 31c → auxiliary heat exchangers 35a to 35d → compressor 20”. The temperature of the precooling refrigerant in each refrigeration cycle is lowered by adiabatic expansion in the expansion valves 36a to 36d and 37a to 37d.

However, in the expansion valves 36a to 36d and 37a to 37d, part of the energy of the precooling refrigerant is lost in the process of adiabatic expansion, so that high refrigeration cycle efficiency cannot be obtained. In this regard, in the process of adiabatic expansion of the precooling refrigerant, if the work done by the liquid is recovered as the pressure energy of the precooling refrigerant (gas), the low-pressure side suction amount of the compressor 20 is reduced and the load on the compressor 20 is reduced. And the efficiency of the refrigeration cycle can be improved.

Based on the above idea, the refrigeration apparatus of the present embodiment uses an ejector 41a that reduces the low-pressure side suction amount of the compressor 20 using the energy of the precooling refrigerant in the process of adiabatic expansion of the precooling refrigerant. It has. Hereinafter, a configuration example of the refrigeration apparatus including the ejector 41a will be described with reference to FIGS.
In FIGS. 2 and 4 to 6 described below, the same reference numerals as those used in FIG. 7 are attached to the same components as those described using FIG.

The refrigeration apparatus shown in FIG. 2 is provided with an ejector 41a in place of the expansion valve 36a on the inlet side of the first-stage precooling heat exchanger 34a, and the ejector 41a provides a second-stage precooling heat exchanger 34b. 7 is different from the conventional refrigeration apparatus shown in FIG. 7 in that a part of the precooling refrigerant gas generated is sucked.
In FIG. 2, the first stage preheat exchanger 34a corresponds to the first stage heat exchanger, and the second stage preheat exchanger 34b corresponds to the next stage heat exchanger. The ejector 41a corresponds to the first-stage ejector, and the expansion valve 36b provided between the first-stage and second-

stage preheat exchangers

34a and 34b corresponds to the expansion section.

FIG. 3 shows an example of the configuration of each ejector 41a (in FIG. 3, reference numeral “41” is given as a general description including each ejector 41b to 41g described later). In the ejector 41, a nozzle 412 for supplying a precooling refrigerant liquid (high-pressure refrigerant liquid) to a tubular main body 416 whose rear end portion is sealed is coaxially inserted from the rear end portion side. Yes. Further, a suction port 413 for sucking a precooling refrigerant gas into the main body 416 is provided on a side surface of the main body 416, and the suction port 413 is connected to a pipe for extracting gas from the precooling heat exchangers 34a to 34d. Has been. In addition, the distal end side of the main body 416 is reduced in diameter in the liquid discharge direction from the nozzle 412, and the downstream side of the discharge port of the nozzle 412 is a mixing unit 414 made of a pipe having a smaller diameter than the main body 416. It has become. A diffuser portion 415 having a gradually increasing pipe diameter is provided on the outlet side of the mixing portion 414. The ejector 41 is connected to the precooling refrigerant introduction pipe to the gas-liquid separators 33a to 33d via the diffuser portion 415. Is done.

In the ejector 41 having the above-described configuration, when the precooling refrigerant (liquid) accelerated at high speed in the nozzle 412 is discharged from the nozzle 412, the fluid in the main body 416 is drawn toward the precooling refrigerant flowing at high speed. The precooling refrigerant (gas) is sucked from the suction port 413. For example, in FIG. 2, most of the precooling refrigerant extracted from the second stage precooling heat exchanger 34b is gas, but is accompanied by a mist-like liquid of about 1.0 wt% at most. The ejector 41a sucks the precooling refrigerant gas and the liquid accompanying it from the precooling heat exchanger 34b. In the following description, the precooling refrigerant gas and the liquid accompanying it may be collectively referred to as “gas”.

Further, the temperature of the precooling refrigerant discharged from the nozzle 412 decreases due to adiabatic expansion.
The precooling refrigerant (liquid) discharged from the nozzle 412 and the precooling refrigerant (gas) sucked from the suction port 413 flow through the mixing unit 414 as a gas-liquid mixed fluid while being mixed with each other, and enter the diffuser unit 415. Decelerate and the pressure recovers.
The configuration of the ejector 41 provided in the refrigeration apparatus is not limited to the example shown in FIG. 3, and the precooling refrigerant (gas) is sucked using the precooling refrigerant (liquid), and the mixed fluid thereof. As long as the voltage is increased, the configuration of each part may be changed as appropriate.

Next, a refrigeration apparatus including the above-described ejector 41a will be described in detail with reference to FIG.
The precooling refrigerant (liquid) supercooled by the AFC 31c is supplied to the nozzle 412 provided in the ejector 41a on the precooling heat exchange section 103 side. On the other hand, the suction port 413 of the ejector 41a is connected to a flow path 501 branched from the flow path 502 for introducing the precooling refrigerant gas generated in the second stage precooling heat exchanger 34b to the gas-liquid separator 33b. ing. As a result, the precooling refrigerant gas (including the accompanying liquid) is diverted from the flow to the second-stage gas-liquid separator 33b and supplied to the suction port 413. And the exit side of the diffuser part 415 of the ejector 41a from which the gas-liquid mixed fluid of the precooling refrigerant flows out is connected to the first stage precooling heat exchanger 34a. The gas-

liquid separators

33a, 33b, 33c, and 33d separate mist (liquid) accompanying the refrigerant gas, and correspond to, for example, a knockout drum.

Here, each of the gas-

liquid separators

33a and 33b corresponds to a first-stage gas-liquid separator and a next-stage gas-liquid separator, and the above-described flow path 502 is “the next-stage heat exchanger (second-stage preheat exchanger 34b)”. This corresponds to the “flow path for supplying the refrigerant gas generated by heat exchange in the gas and the liquid accompanying the refrigerant gas (also referred to as“ second-stage gas ”) to the gas-liquid separator 33b in the next stage”. Further, the flow path 501 corresponds to “a flow path for supplying (second-stage gas) to the suction port 413 of the first-stage (first-stage) ejector 41a”.

The pressure of the precooling refrigerant gas (second stage gas) generated in the second stage precooling heat exchanger 34b into which the precooling refrigerant adiabatically expanded using the expansion valve 36b flows is the first stage preheating temperature. It is lower than the pressure of the precooling refrigerant gas (also referred to as “first stage gas”) generated in the cold heat exchanger 34a. In the conventional refrigeration apparatus described with reference to FIG. 7, the entire amount of the second-stage gas is returned to the suction port of the compressor 20 via the gas-liquid separator 33b.

However, in order to compress the second-stage gas having a low pressure by the compressor 20 to obtain the liquid for the precooling refrigerant, more energy is required than the first-stage gas. Therefore, the refrigeration apparatus of this example uses the ejector 41 a to increase the pressure of the second stage gas returned to the compressor 20, thereby reducing the amount of the second stage gas returned to the compressor 20. The load on the compressor 20 is reduced.

Comparing the refrigeration apparatus of the present example shown in FIG. 2 having the above-described configuration with the conventional refrigeration apparatus shown in FIG. 7, the refrigeration apparatus of the present example includes a first-stage precooling heat exchanger 34a. An ejector 41a is provided on the inlet side instead of the expansion valve 36a. As described above, the expansion valve 36a provided in the conventional device has a function of increasing or decreasing the supply amount of the precooling refrigerant based on the liquid level in the precooling heat exchanger 34a.

Correspondingly, in the ejector 41a (41) of the refrigeration apparatus of the present example, a flow rate for increasing or decreasing the supply amount of the precooling refrigerant based on the liquid level detected by the liquid level gauge 341a of the precooling heat exchanger 34a. A regulating valve 411 is provided. As shown in FIG. 3, for example, the flow rate adjustment valve 411 is provided on the base end side of the nozzle 412. Here, the flow rate adjustment valve 411 is preferably provided integrally with the nozzle 412 as a part of the equipment constituting the ejector 41. However, for example, the flow rate adjusting valve 411 may be independently provided on the upstream side of the precooling refrigerant (liquid) supply pipe connected to the nozzle 412 that does not include the flow rate adjusting valve 411.

As an example of the control executed by the flow rate adjusting valves 411 of these ejectors 41a to 41d, when the liquid level in the precooling heat exchanger 34a is lower than the target value, the opening degree of the flow rate adjusting valve 411 is increased. Then, while increasing the supply amount of the precooling refrigerant, when the liquid level is higher than the target value, control is performed to reduce the supply amount of the precooling refrigerant by reducing the opening degree of the flow rate adjustment valve 411.

In addition to the configuration described above, the second and subsequent precooling heat exchangers 34b to 34d on the precooling heat exchanging portion 103 side, the expansion valves 36b to 36d on the inlet side, and the auxiliary heat exchangers on the auxiliary heat exchanging portion 105 side. The configurations of 35a to 35d, the expansion valves 37a to 37d on the inlet side, and the gas-liquid separators 33a to 33d are the same as those of the conventional refrigeration apparatus described with reference to FIG.

Hereinafter, the operation of the refrigeration apparatus of this example will be described. When the supplied precooling refrigerant (liquid) subcooled in the AFC 31c is supplied to the first precooling heat exchanger 34a on the precooling heat exchange section 103 side, the liquid level of the precooling heat exchanger 34a is supplied. Accordingly, the supply amount to the ejector 41a is increased or decreased. In the ejector 41a, the suction amount of the second-stage gas (including the accompanying liquid) increases or decreases in accordance with the supply amount of the precooling refrigerant (liquid).

The pressure of the second stage gas discharged from the ejector 41a and the mixed fluid of the precooling refrigerant liquid and gas whose temperature has decreased due to adiabatic expansion are introduced into the first stage precooling heat exchanger 34a, NG flowing on the tube side is cooled. The precooling heat exchanger 34a performs gas-liquid separation of the precooling refrigerant, and the gas of the precooling refrigerant is returned to the high-pressure side suction port of the compressor 20 via the gas-liquid separator 33a.

On the other hand, the liquid in the precooling heat exchanger 34a is extracted toward the second stage precooling heat exchanger 34b, and passes through the expansion valve 36b in accordance with the liquid level in the precooling heat exchanger 34b. The amount of refrigerant (liquid) is increased or decreased. In the second stage pre-cooling heat exchanger 34b, NG cooling and gas-liquid separation of the pre-cooling refrigerant gas and liquid are performed, and the gas is returned to the compressor 20 via the gas-liquid separator 33b.

A part of the precooling refrigerant gas flowing toward the gas-liquid separator 33b is divided and sucked from the suction port 413 of the ejector 41a. After the pressure is increased and returned to the compressor 20, the compressor 20 The load can be reduced.
Hereinafter, the actions of the

pre-cooling heat exchangers

34c and 34d after the third stage, the

expansion valves

36c and 36d, and the auxiliary heat exchangers 35a to 35d and the expansion valves 37a to 37d on the auxiliary heat exchanging unit 105 side will be described with reference to FIG. Since it is the same as that of the conventional refrigeration apparatus explained using, the explanation is omitted again.

The refrigeration apparatus according to the present embodiment has the following effects. The refrigeration apparatus cools NG using a precooling refrigerant, and is connected to a first stage precooling heat exchanger 34a (first stage heat exchanger) and two stages connected in series via an expansion valve 36b (expansion part). Refrigeration including a pre-cooling heat exchanger 34b (next-stage heat exchanger), and a refrigerant gas generated in each

heat exchanger

34a, 34b is compressed by the compressor 20 to obtain a pre-cooling refrigerant (high-pressure refrigerant liquid) Provide a cycle. When the temperature is lowered by the adiabatic expansion of the precooling refrigerant, pressure is increased by sucking a part of the precooling refrigerant gas generated in the second stage precooling heat exchanger 34b using the ejector 41a. For this reason, the supply amount to the compressor 20 of the precooling refrigerant gas generated in the second stage precooling heat exchanger 34b having a relatively low pressure is reduced, and the load on the compressor 20 is reduced. Refrigeration cycle can be realized.

2 shows an example in which the ejector 41a is provided only on the inlet side of the first stage precooling heat exchanger 34a on the precooling heat exchanging unit 103 side, the ejector 41 is provided. The position is not limited to this example.
For example, FIG. 4 shows the first to third stage precooling heat exchangers 34a to 34c on the precooling heat exchange unit 103 side, and the first to third stage auxiliary heat exchangers 35a to 35c on the auxiliary heat exchange unit 105 side. A refrigerating apparatus is shown in which ejectors 41a to 41f are provided on the respective inlet sides of 35c. Since no heat exchanger is provided on the further lower side of the fourth stage pre-cooling heat exchanger 34d and auxiliary heat exchanger 35d, an expansion valve 36d is provided on the inlet side of these

heat exchangers

34d and 35d. , 37d.

The ejectors 41a to 41c provided at the inlets of the precooling heat exchangers 34a to 34c are branched from flow paths 502a to 502c respectively leading from the precooling heat exchangers 34b to 34d downstream to the gas-liquid separators 33b to 33d. The precooling refrigerant gas is sucked through the flow paths 501a to 501c. Similarly, the ejectors 41d to 41f provided at the inlets of the auxiliary heat exchangers 35a to 35c are respectively connected from the flow paths 502d to 502f directed from the auxiliary heat exchangers 35b to 35d downstream by one stage to the gas-liquid separators 33b to 33d. The precooling refrigerant gas is sucked through the branched flow paths 501d to 501f. Here, the refrigerant gas generated by heat exchange in the pre-cooling heat exchanger or auxiliary heat exchanger downstream of the first stage and the liquid accompanying the refrigerant gas may be supplied to the suction port of the ejector in the previous stage. .

When the first stage precooling heat exchanger 34a on the side of the precooling heat exchanging section 103 is viewed as the first stage heat exchanger, and the second stage precooling heat exchanger 34b is viewed as the next stage heat exchanger, the first stage side ejector 41a corresponds to the first-stage ejector, and the second-stage ejector 41b corresponds to the inflatable portion and the next-stage ejector. The second-stage precooling heat exchanger 34b is regarded as a first-stage heat exchanger in which the precooling refrigerant (liquid) from the compressor 20 is supplied via the first-stage precooling heat exchanger 34a. In this case, the third-stage precooling heat exchanger 34c corresponds to the next-stage heat exchanger. In this case, it can be said that the ejector 41c on the third stage side corresponds to a next-stage ejector (expansion section) that expands the refrigerant liquid supplied to the third-stage precooling heat exchanger 34c.

The same correspondence is also established on the auxiliary heat exchanger 105 side, and the first stage auxiliary heat exchanger 35a is regarded as the first stage heat exchanger, and the second stage auxiliary heat exchanger 35b is regarded as the next stage heat exchanger. In this case, the first-stage ejector 41d corresponds to the first-stage ejector, and the second-stage ejector 41e corresponds to the next-stage ejector as well as the expansion portion. The second stage auxiliary heat exchanger 35b is regarded as a first stage heat exchanger in which the precooling refrigerant (liquid) from the compressor 20 is supplied via the first stage auxiliary heat exchanger 35a. In this case, the third stage auxiliary heat exchanger 35c corresponds to the next stage heat exchanger. In this case, it can be said that the ejector 41f on the third stage side corresponds to a next-stage ejector (expansion section) that expands the refrigerant liquid supplied to the third stage auxiliary heat exchanger 35c.

Further, in FIG. 4, “first stage ejector 41 a, precooling heat exchanger 34 a, second stage ejector 41 b, precooling heat exchanger 34 b” on the precooling heat exchanging section 103 side is NG (first cooled fluid). The “first-stage ejector 41d, auxiliary heat exchanger 35a, second-stage ejector 41e, auxiliary heat exchanger 35b” on the auxiliary heat exchanging portion 105 side is the main set. This corresponds to a second set for cooling the refrigerant (second fluid to be cooled). The first-stage gas-liquid separator 33a and the next-stage gas-liquid separator 33b are provided in common for the first group and the second group.

Further, here, when there are two refrigeration cycles of the precooling heat exchanging unit 103 side and the auxiliary heat exchanging unit 105 side, as shown in FIG. 4, the ejector 41 provided in the one side system is in the same system. It is not essential that the precooling refrigerant gas generated in step 1 is sucked.
For example, in FIG. 5, ejectors 41a to 41c are provided at the inlets of the first to third stage precooling heat exchangers 34a to 34c on the precooling heat exchange unit 103 side, and the auxiliary heat exchange unit 105 side is provided with the first stage auxiliary cooling unit. The example which provided the ejector 41d only in the inlet_port | entrance of the heat exchanger 35a is shown.

For the first-stage ejector 41d on the auxiliary heat exchanging portion 105 side, the second-stage gas on the auxiliary heat exchanging portion 105 side goes to the gas-liquid separator 33b as in the example shown in FIG. The precooling refrigerant gas is sucked through the flow path 501d branched from the flow path 502d. In the refrigeration apparatus of this example, a flow path 501g for supplying a precooling refrigerant gas to the first-stage ejector 41a on the precooling heat exchange section 103 side is further branched from the flow path 501d. In summary, the second-stage gas on the auxiliary heat exchange unit 105 side is sucked into the

ejectors

41 a and 41 d of both systems of the precooling heat exchange unit 103 and the auxiliary heat exchange unit 105.

When attention is paid to the liquid flow of the precooling refrigerant, the precooling refrigerant (liquid) in the second and third stage precooling

heat exchangers

34b and 34c on the precooling heat exchanging unit 103 side is the third and fourth stage, respectively. The

pre-cooling heat exchangers

34c and 34d and the

auxiliary heat exchangers

35c and 35d at the third and fourth stages on the auxiliary heat exchanging unit 105 side are divided and supplied.

Further, for the second and

third stage ejectors

41b and 41c on the precooling heat exchange section 103 side, the precooling generated in the third and fourth stage

auxiliary heat exchangers

35c and 35d on the auxiliary heat exchange section 105 side is provided.

Flow paths

501h and 501i are provided for diverting a part of the refrigerant gas (also referred to as “third and fourth stage gas”) and sucking them by these

ejectors

41b and 41c.
As described above, the gas supplied to each ejector 41 includes the amount of precooling refrigerant gas generated in each of the heat exchangers 34b to 34d and 35b to 35d, and the precooling in the heat exchangers 34a to 34c and 35a to 35c. An appropriate supply source can be selected from the balance of the amount of refrigerant used.

In FIG. 5, for example, the first-stage ejector 41a and the pre-cooling heat exchanger 34a on the pre-cooling heat exchange section 103 side are called a first first-stage ejector and a first first-stage heat exchanger, and the second-stage ejector 41b. When the precooling heat exchanger 34b is called a first next-stage ejector and a first next-stage heat exchanger, the first-stage ejector 41d and the auxiliary heat exchanger 35a on the auxiliary heat exchanging unit 105 side are The second pre-stage heat exchanger 35b corresponds to the second first-stage ejector and the second first-stage heat exchanger, and the second pre-stage heat exchanger 35b is provided with an expansion valve 37b (expansion part) on the inlet side. It corresponds to a heat exchanger. Then, the flow path 501d is “the refrigerant gas heat-exchanged in the second next-stage heat exchanger (second-stage auxiliary heat exchanger 35b) and the liquid accompanying the refrigerant gas (second-stage gas). Corresponds to the “flow path to be supplied to the suction port 413 of the ejector 41d of the second first stage (first stage)”.

Next, the refrigeration apparatus shown in FIG. 6 includes an ejector 41g provided in parallel with the expansion valve 37a on the inlet side of the first stage auxiliary heat exchanger 35a on the auxiliary heat exchanging unit 105 side. Precooling refrigerant gas generated in the other system heat exchanger 38 that cools the fluid to be cooled that flows through a system different from the precooling heat exchange unit 103 that cools the NG and the auxiliary heat exchange unit 105 that cools the main refrigerant. It is different from the conventional refrigeration apparatus shown in FIG. 7 in that the pressure is increased by sucking (including the accompanying liquid).

From the first stage auxiliary heat exchanger 35a on the side of the auxiliary heat exchanger 105, the second stage auxiliary heat exchanger 35b of the same system and the other system heat exchanger 38 are used for precooling inside thereof. A refrigerant (liquid) is supplied in a diverted state. The liquid level of the precooling refrigerant in the other system heat exchanger 38 is adjusted by an expansion valve 39 provided on the inlet side.

Further, the increase / decrease in the supply amount of the precooling refrigerant by the flow rate adjustment valve 411 provided in the ejector 41g is indicated by a pressure gauge that measures the pressure on the outlet side of the other system heat exchanger 38 (pressure of the precooling refrigerant gas). The value is adjusted to be the target value. That is, when the pressure is lower than the target value, the opening amount of the flow rate adjustment valve 411 is reduced to reduce the suction amount of the precooling refrigerant gas (including the accompanying liquid), while the pressure is the target value. If higher, control is performed to increase the suction amount of the gas by increasing the opening degree of the flow rate adjustment valve 411.

As an example of the fluid to be cooled that is cooled by the other system heat exchanger 38, when a gas turbine that drives the compressor 20 is provided, a refrigerant that can be used for a chiller that lowers the supply temperature of the gas turbine ( For example, cooling water), deethanizer top liquid for removing heavy components such as ethane in NG, LPG obtained by rectifying the heavy components, and the like.

In this way, by extending the installation object of the ejector 41g to the other system heat exchanger 38 that cools the fluid to be cooled different from NG and the main refrigerant, among the many heat exchangers in the natural gas liquefaction system, Therefore, it is possible to select a suitable material for recovering the pressure energy of the precooling refrigerant.

In the example shown in FIG. 6, when the first stage auxiliary heat exchanger 35a on the side of the auxiliary heat exchanging section 105 is the first stage heat exchanger, the expansion valve 37a provided on the inlet side thereof is connected to the ejector 41g. It corresponds to the first stage expansion valve provided in parallel. The other system heat exchanger 38 corresponds to a heat exchanger in the next stage of another system, and the expansion valve 39 provided on the inlet side thereof corresponds to an expansion section.

Thus, FIG. 6 shows the auxiliary heat exchanger 35a on the auxiliary heat exchange unit 105 side of the two systems on the precooling heat exchange unit 103 side and the auxiliary heat exchange unit 105 side as the first stage heat exchanger. An embodiment in which an auxiliary heat exchanger 35b, which is a next-stage heat exchanger, and another system heat exchanger 38, which is a next-stage heat exchanger of another system, is provided in parallel to the subsequent stage of the heat exchanger 35a. .
However, the present invention is not limited to the example shown in FIG. 6, and the precooling heat exchanger 34 a on the precooling heat exchange unit 103 side is used as a first stage heat exchanger, and the inlet side of the precooling heat exchanger 34 a is A first-stage ejector 41 is provided in parallel with the expansion valve 36a (first-stage expansion valve), a pre-cooling heat exchanger 34b, which is a next-stage heat exchanger, and a second-stage heat exchanger, which is a separate system, in the subsequent stage. The system heat exchanger 38 may be provided in parallel.
In this way, the system (precooling heat exchanging unit 103 and auxiliary heat exchanging unit 105) provided with the first stage expansion valve and the second stage heat exchanger of another system is appropriately selected.

As described above, in each example of the refrigeration apparatus described with reference to FIGS. 2, 4 to 6, the system and the number of installed ejectors 41a to 41g may be appropriately changed. For example, the conventional expansion valves 36a to 36c, 37a to 37c are replaced with ejectors 41a to 41f (FIGS. 2, 4, and 5), or the ejector 41g is newly connected to the other system heat exchanger 38 (FIG. 6). The ejectors 41a to 41g may be provided at the position where the merit is greatest.
In general, among the expansion valves 36a to 36d and 37a to 37d, the upstream side expansion valve has a larger pressure difference before and after adiabatic expansion, and the effect of replacing it with the ejectors 41a to 41f increases. There is a tendency to become larger toward the step side.

20 Compressors 33a-33d
Gas-liquid separator (knockout drum)
331a to 331d
Level gauges 34a to 34d
Pre-cooling heat exchangers 341a-341d
Level gauges 342a to 342d
Liquid level control valves 35a-35d
Auxiliary heat exchangers 36a-36d
Expansion valves 37a-37d
Expansion valve 38 Other system heat exchanger 382

Pressure gauge

41, 41a to 41g
Ejector 411 Flow adjustment valve

Claims

A compressor for compressing the refrigerant gas;
A high-pressure refrigerant liquid obtained by condensing the high-pressure refrigerant gas discharged from the compressor is injected, and a suction port for sucking the refrigerant gas by the injection of the high-pressure refrigerant liquid is injected from the nozzle. A first-stage ejector for increasing the pressure of the mixed fluid of the high-pressure refrigerant liquid and the refrigerant gas sucked from the suction port;
A first-stage heat exchanger that is supplied with the mixed fluid pressurized by the first-stage ejector, heat-exchanged between the mixed fluid and the fluid to be cooled, and cools the fluid to be cooled;
Gas-liquid separation of the refrigerant gas generated by heat exchange in the first-stage heat exchanger and the liquid accompanying the refrigerant gas, and the first-stage gas-liquid separator in which the separated refrigerant gas is sent to the compressor;
The refrigerant obtained by expanding the refrigerant liquid that has not been vaporized in the first stage heat exchanger by the expansion unit is supplied, and heat exchange is performed between the refrigerant and the fluid to be cooled to cool the fluid to be cooled. A next stage heat exchanger,
A refrigeration apparatus comprising: a refrigerant gas generated by heat exchange in the next-stage heat exchanger and a flow path for supplying a liquid accompanying the refrigerant gas to a suction port of the first-stage ejector.
The expansion section includes a nozzle from which high-pressure refrigerant liquid is injected and a suction port that sucks refrigerant gas by the injection of the high-pressure refrigerant liquid, and the high-pressure refrigerant liquid injected from the nozzle and the refrigerant sucked from the suction port 2. The refrigeration apparatus according to claim 1, wherein the refrigeration apparatus is a next-stage ejector that pressurizes a mixed fluid with gas.
Gas-liquid separation of the refrigerant gas generated by heat exchange in the next-stage heat exchanger and the liquid accompanying the refrigerant gas, and the separated gas-liquid separator in which the separated refrigerant gas is sent to the compressor;
A refrigerant gas generated by heat exchange in the next-stage heat exchanger and a flow path for supplying liquid accompanying the refrigerant gas to the next-stage gas-liquid separator,
The refrigerant gas generated by heat exchange in the next-stage heat exchanger and the liquid accompanying the refrigerant gas are supplied separately to the suction port of the first-stage ejector and the gas-liquid separator in the next stage. The refrigeration apparatus according to claim 1, wherein the refrigeration apparatus is configured.
The expansion part which is a constituent requirement of the refrigeration apparatus according to claim 1 is an ejector of the next stage,
The first stage ejector, the first stage heat exchanger, the second stage ejector, and the second stage heat exchanger, which are constituent elements of the refrigeration apparatus according to claim 3, are used to cool the first cooled fluid. 1 set and a second set for cooling the second cooled fluid are provided,
A high-pressure refrigerant liquid obtained by condensing the high-pressure refrigerant gas discharged from the compressor is separately supplied to each nozzle of the first-stage ejector of the first group and the first-stage ejector of the second group. That
The first-stage gas-liquid separator is common to the first group and the second group, and the next-stage gas-liquid separator is common to the first group and the second group. The refrigeration apparatus according to claim 3, further comprising:
A high-pressure refrigerant liquid obtained by condensing the high-pressure refrigerant gas discharged from the compressor is divided and supplied, and a nozzle from which the high-pressure refrigerant liquid is injected and a suction port for sucking the refrigerant gas by the injection of the high-pressure refrigerant liquid And provided in parallel two first-stage ejectors for boosting the mixed fluid of the high-pressure refrigerant liquid ejected from the nozzle and the refrigerant gas sucked from the suction port,
If the first-stage ejector on one side is called the first first-stage ejector and the first-stage ejector on the other side is called the second-first ejector,
The mixed fluid pressurized by the first first-stage ejector is supplied, heat exchange is performed between the mixed fluid and the fluid to be cooled to cool the fluid to be cooled, and the refrigerant generated by heat exchange. The first fluid heat exchanger, which is the first heat exchanger in which the gas and the liquid accompanying the gas are supplied to the first gas-liquid separator, and the mixed fluid pressurized by the second first ejector are Providing a second first-stage heat exchanger, which is a first-stage heat exchanger to be supplied;
A first next stage expansion section, a first next stage heat exchanger, and a next stage gas-liquid separator are provided after the first first stage heat exchanger, and the second first stage heat exchanger The second stage is provided with a second next stage expansion section and a second next stage heat exchanger.
The refrigerant liquid that has not been vaporized in the first first-stage heat exchanger is supplied as a high-pressure refrigerant to the first next-stage heat exchanger via the first next-stage expansion section, and the second first-stage heat exchanger is supplied. The refrigerant liquid that has not been vaporized by the second heat exchanger is supplied as a high-pressure refrigerant to the second next-stage heat exchanger via the second next-stage expansion section. Provided with a flow path for supplying the refrigerant gas heat-exchanged in the next-stage heat exchanger and the accompanying liquid to the suction port of the first-stage first-stage ejector and the next-stage gas-liquid separator ,
The first first-stage heat exchanger and the first next-stage heat exchanger are for cooling the first cooled fluid, and the second first-stage heat exchanger and the second next-stage heat exchanger 2. The refrigeration apparatus according to claim 1, wherein the stage heat exchanger is for cooling the second fluid to be cooled.
In the flow path for supplying the refrigerant gas heat-exchanged in the second next-stage heat exchanger and the liquid accompanying the refrigerant gas to the suction port of the first first-stage ejector and the next-stage gas-liquid separator 6. The refrigeration apparatus according to claim 5, further comprising a flow path that supplies a suction port of the second first-stage ejector.
A refrigeration apparatus used in a natural gas liquefaction system that precools natural gas with a precooling refrigerant, then main cools with a main refrigerant, and cools the main refrigerant after the main cooling is compressed with the precooling refrigerant after compression,
The high-pressure refrigerant is a precooling refrigerant,
The refrigeration apparatus according to claim 4, 5 or 6, wherein the first cooled fluid and the second cooled fluid are natural gas and main refrigerant, respectively.
A high-pressure refrigerant liquid obtained by condensing the high-pressure refrigerant gas discharged from the compressor is supplied to a first-stage expansion valve provided in parallel with the first-stage ejector. The refrigerant obtained by expansion is supplied to the first-stage heat exchanger,
From the rear stage of the first stage heat exchanger, the second stage heat exchanger of another system to which the refrigerant to be supplied to the next stage heat exchanger is supplied in a branched manner,
A flow path for supplying the refrigerant gas generated by heat exchange in the next-stage heat exchanger of the different system and the liquid accompanying the refrigerant gas to the suction port of the first-stage ejector,
The heat exchanger of the next stage of the different system is obtained by expanding the refrigerant liquid that has not been vaporized in the heat exchanger of the first stage by an expansion unit provided on the inlet side of the heat exchanger of the next stage of the different system. The supplied refrigerant is supplied, heat exchange is performed between the refrigerant and the fluid to be cooled to cool the fluid to be cooled, and the fluid to be cooled includes the first stage heat exchanger and the next stage heat exchanger. The refrigerating apparatus according to claim 1, wherein the refrigerating apparatus is different from the fluid to be cooled by cooling.