Refrigerant circulating device and natural gas liquefaction system

Abstract

The utility model discloses a refrigerant circulating device and a natural gas liquefaction system, a refrigerant circulating flow path is formed on the refrigerant circulating device, the refrigerant circulating device comprises a compressor and a refrigerant expansion device, the compressor is arranged on the refrigerant circulating flow path, the refrigerant expansion device is arranged on the refrigerant circulating flow path, and the refrigerant expansion device is in driving connection with the compressor. The refrigerant expansion device is used for assisting the compressor to work, the refrigerant expansion device is arranged to enable the refrigerant to depressurize and do work, compared with throttling depressurization of a traditional throttling valve, the refrigerant expansion device can utilize pressure energy to do work, energy loss in the depressurization process is reduced, meanwhile, the refrigerant expansion device is in driving connection with the compressor, and therefore the compressor can work more stably. The refrigerant expansion device can assist the compressor in doing work, the energy consumption of the compressor can be reduced, the energy utilization rate of the refrigerant circulating device can be effectively increased, the energy consumption of the refrigerant circulating device can be reduced, and therefore the problem that the energy consumption is high due to the fact that an existing natural gas liquefaction device is large in throttling loss is solved.

Description

Technical Field

[0001] The utility model relates to the technical field of natural gas liquefaction, in particular to a refrigerant circulation device and a natural gas liquefaction system. Background Art

[0002] Currently, natural gas liquefaction mostly adopts the mixed refrigerant liquefaction process. The liquefaction process of this process is efficient and simple. Most natural gas liquefaction devices adopt this process. However, this process usually uses a throttle valve to throttle and reduce the pressure, and the throttling loss is large, resulting in high energy consumption in the entire cycle process. Utility Model Content

[0003] The main purpose of the utility model is to provide a refrigerant circulation device and a natural gas liquefaction system, aiming to solve the problem of large throttling loss and high energy consumption of the existing natural gas liquefaction device.

[0004] To achieve the above object, the utility model provides a refrigerant circulation device for a natural gas liquefaction system, wherein a refrigerant circulation flow path is formed on the refrigerant circulation device, and the refrigerant circulation device comprises:

[0005] A compressor is provided in the refrigerant circulation flow path; and

[0006] A refrigerant expansion device is arranged in the refrigerant circulation flow path, and the refrigerant expansion device is driven and connected to the compressor so that the refrigerant expansion device can assist the compressor in working.

[0007] Optionally, the refrigerant expansion device includes a piston motor, so that the refrigerant passing through the piston motor can expand and perform work.

[0008] Optionally, a plurality of refrigerant expansion devices are provided.

[0009] Optionally, the refrigerant circulation flow circuit includes a refrigerant main circuit and multiple refrigerant branches connected to the refrigerant main circuit, the multiple refrigerant branches are arranged in parallel, the multiple refrigerant expansion devices are respectively arranged in the multiple refrigerant branches, and the multiple refrigerant expansion devices drive and connect the compressor.

[0010] Optionally, a plurality of the compressors are provided, and the refrigerant expansion devices on different refrigerant branches are at least partially driven to connect to different compressors.

[0011] Optionally, the compressor is provided in plurality.

[0012] Optionally, the refrigerant expansion device is driven and connected to the compressor via a mechanical transmission structure to transmit the torque of the refrigerant expansion device to the compressor.

[0013] Optionally, the refrigerant circulation device further includes a gas-liquid separator arranged on the refrigerant circulation flow path.

[0014] Optionally, the refrigerant circulation circuit includes a refrigerant trunk circuit and a multi-stage refrigerant branch circuit connected to the refrigerant trunk circuit, and a plurality of gas-liquid separators are provided;

[0015] The two refrigerant branches at the same level are respectively connected to the liquid phase outlet and the gas phase outlet of the corresponding gas-liquid separator;

[0016] The refrigerant branch circuit or the refrigerant trunk circuit at the previous stage is connected to the inlet of the corresponding gas-liquid separator.

[0017] Optionally, the refrigerant circulation device further includes a cold box and a mounting platform disposed outside the cold box;

[0018] Wherein, the refrigerant expansion device is arranged in the cold box, and the compressor is arranged on the installation platform.

[0019] In addition, the utility model also provides a natural gas liquefaction system, including the above-mentioned refrigerant circulation device.

[0020] In the technical solution of the utility model, the compressor is arranged in the refrigerant circulation flow path to convert the low-temperature and low-pressure gaseous refrigerant into the high-temperature and high-pressure gaseous refrigerant. The refrigerant expansion device is arranged in the refrigerant circulation flow path to enable the refrigerant to reduce pressure and expand, so as to convert the pressure energy of the refrigerant into mechanical energy so as to do work externally. The refrigerant expansion device drives and connects to the compressor so that the refrigerant expansion device can assist the compressor in compression. In this way, by setting the refrigerant expansion device so that the refrigerant can reduce pressure and do work, compared with the throttling and pressure reduction of the traditional throttle valve, the refrigerant expansion device can use pressure energy to do work and reduce energy loss in the pressure reduction process. At the same time, the refrigerant expansion device drives and connects to the compressor so that the refrigerant expansion device can assist the compressor in doing work, which is beneficial to reducing the energy consumption of the compressor, and can effectively improve the energy utilization rate of the refrigerant circulation device and reduce the energy consumption of the refrigerant circulation device, thereby solving the problem of large throttling loss and high energy consumption of the existing natural gas liquefaction device. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the embodiments of the utility model or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0022] Figure 1A system flow chart of the refrigerant circulation device provided by the utility model;

[0023] Figure 2 for Figure 1 Schematic diagram of the three-dimensional structure of the cold box.

[0024] Description of Figure Numbers:

[0025] Label name Label name 100 Refrigerant circulation device 4 Mechanical transmission structure 1 Refrigerant circulation path 5 Gas-Liquid Separator 11 Refrigerant trunk road 6 Condenser 12 Refrigerant branch 7 Evaporator 2 compressor 8 Cold Box 3 Refrigerant expansion device 81 Installation Platform

[0026] The realization of the purpose, functional features and advantages of the utility model will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0027] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0028] It should be noted that if a directional indication is involved in the embodiments of the present invention, the directional indication is only used to explain the relative position relationship, movement status, etc. between the components in a certain specific posture. If the specific posture changes, the directional indication will also change accordingly.

[0029] In addition, if there are descriptions involving "first", "second", etc. in the embodiments of the utility model, the descriptions of "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or suggesting their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In addition, the technical solutions between the various embodiments can be combined with each other, but they must be based on the ability of ordinary technicians in the field to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the utility model.

[0030] Currently, natural gas liquefaction mostly adopts the mixed refrigerant liquefaction process. The liquefaction process of this process is efficient and simple. Most natural gas liquefaction devices adopt this process. However, this process usually uses a throttle valve to throttle and reduce the pressure, and the throttling loss is large, resulting in high energy consumption in the entire cycle process.

[0031] Based on this, the utility model provides a refrigerant circulation device for a natural gas liquefaction system, aiming to solve the problem of large throttling losses and high energy consumption in existing natural gas liquefaction devices. Figure 1 to Figure 2This is a schematic diagram of the refrigerant circulation device provided by the utility model.

[0032] See also Figure 1 A refrigerant circulation flow path 1 is formed on the refrigerant circulation device 100, and the refrigerant circulation device 100 includes a compressor 2 and a refrigerant expansion device 3. The compressor 2 is arranged on the refrigerant circulation flow path 1, and the refrigerant expansion device 3 is arranged on the refrigerant circulation flow path 1. The refrigerant expansion device 3 is driven and connected to the compressor 2 so that the refrigerant expansion device 3 can assist the compressor 2 in its operation.

[0033] In the technical solution of the utility model, the compressor 2 is arranged in the refrigerant circulation flow path 1 to convert the low-temperature and low-pressure gaseous refrigerant into a high-temperature and high-pressure gaseous refrigerant. The refrigerant expansion device 3 is arranged in the refrigerant circulation flow path 1 to enable the refrigerant to reduce pressure and expand, so as to convert the pressure energy of the refrigerant into mechanical energy so as to do work externally. The refrigerant expansion device 3 drives and connects to the compressor 2 so that the refrigerant expansion device 3 can assist the compressor 2 in compression. In this way, by setting the refrigerant expansion device 3, the refrigerant can reduce pressure and do work. Compared with the throttling and pressure reduction of the traditional throttle valve, the refrigerant expansion device 3 can use pressure energy to do work and reduce energy loss in the pressure reduction process. At the same time, the refrigerant expansion device 3 drives and connects to the compressor 2 so that the refrigerant expansion device 3 can assist the compressor 2 in doing work, which is beneficial to reducing the energy consumption of the compressor 2, and can effectively improve the energy utilization rate of the refrigerant circulation device 100 and reduce the energy consumption of the refrigerant circulation device 100, thereby solving the problem of large throttling loss and high energy consumption of the existing natural gas liquefaction device.

[0034] It should be noted that in order to enable the refrigerant circulation device 100 to cool down the natural gas, in some embodiments of the utility model, the refrigerant circulation device 100 also includes a condenser 6 and an evaporator 7 arranged on the refrigerant circulation flow path 1, and along the circulation direction of the refrigerant, the condenser 6, the refrigerant expansion device 3, and the evaporator 7 are arranged in sequence, so that the refrigerant discharged from the exhaust port of the compressor 2 flows into the refrigerant expansion device 3 after condensation by the condenser 6, and after reducing the pressure and doing work in the refrigerant expansion device 3, it flows into the evaporator 7, and after absorbing heat and evaporating in the evaporator 7, it flows back to the compressor 2, wherein the evaporator 7 is set corresponding to the heat exchange device of the natural gas, so that the evaporator 7 can cool down the natural gas, so that the natural gas can be condensed into LNG.

[0035] In some embodiments of the utility model, the refrigerant expansion device 3 includes a piston motor to enable the refrigerant passing through the piston motor to expand and do work. Since the piston motor will not overheat or generate any sparks during operation, there will be no risk of fire or explosion. Therefore, the use of a piston motor can not only convert the pressure energy of the refrigerant into mechanical energy, but also reduce the risk of overheating or sparks during use, thereby helping to improve the safety of the refrigerant circulation device 100. Of course, in its embodiments, the refrigerant expansion device 3 can also be a gear motor or a vane motor, etc., and the utility model does not limit this.

[0036] In some embodiments of the present invention, the number of the refrigerant expansion device 3 can be one or more, and the present invention does not limit this. Specifically, in this embodiment, a plurality of the refrigerant expansion devices 3 are provided. Thus, by providing a plurality of the refrigerant expansion devices 3, the pressure energy of the refrigerant can be utilized in stages, thereby helping to improve the energy utilization rate of the refrigerant circulation device 100.

[0037] Furthermore, there are multiple ways of arranging the multiple refrigerant expansion devices 3. The multiple refrigerant expansion devices 3 can be arranged in series or in parallel, and the utility model does not limit this. Specifically, in the present embodiment, the refrigerant circulation flow path 1 includes a refrigerant main path 11 and multiple refrigerant branch paths 12 connected to the refrigerant main path 11, and the multiple refrigerant branch paths 12 are arranged in parallel. The multiple refrigerant expansion devices 3 are respectively arranged on the multiple refrigerant branch paths 12, and the multiple refrigerant expansion devices 3 are driven to connect to the compressor 2. In this way, by setting up the multiple refrigerant branch paths 12 and the multiple refrigerant expansion devices 3, the refrigerant circulation device 100 can form multi-stage refrigeration to improve the refrigeration effect of the refrigerant circulation device 100. At the same time, the multiple refrigerant expansion devices 3 are driven to connect to the compressor 2, so that the multiple refrigerant expansion devices 3 can assist the compressor 2 in compression. Furthermore, the refrigerant branch 12 and the refrigerant expansion device 3 are correspondingly arranged as a refrigeration group, and three refrigeration groups are arranged. Although the more refrigeration groups there are, the more complex the refrigerant circulation device 100 is and the higher the cost is, the three refrigeration groups are arranged, which can not only ensure the refrigeration effect of the refrigerant circulation device 100, but also take into account the cost of the refrigerant circulation device 100.

[0038] It can be understood that since the pressure energy on each of the refrigerant branches 12 is different, the output torque of the refrigerant expansion device 3 on each of the refrigerant branches 12 is different. In order to enable each of the refrigerant expansion devices 3 to drive the compressor 2, each of the refrigerant expansion devices 3 can be connected through a differential so that each of the refrigerant expansion devices 3 can drive the connected compressor 2.

[0039] In some embodiments of the utility model, a plurality of the compressors 2 are provided, and the refrigerant expansion devices 3 on different refrigerant branches 12 at least partially drive and connect different compressors 2, so that the plurality of refrigerant expansion devices 3 can respectively assist in driving different compressors 2, thereby avoiding excessive power differences between the compressors 2, thereby helping to keep the power of the compressors 2 balanced.

[0040] In some embodiments of the present invention, the number of the compressor 2 can be one or more, and the present invention does not limit this. However, if only one compressor 2 is provided, its compression ratio is relatively large, the cost is relatively high, and it is prone to failure during long-term operation. Therefore, in the present embodiment, multiple compressors 2 are provided. Therefore, by providing multiple compressors 2 to share the load, the risk of damage to the compressor 2 can be reduced, which is beneficial to increasing the service life of the compressor 2, and a compressor 2 with a smaller compression ratio can be used, which is beneficial to reducing the cost of the compressor 2.

[0041] In some embodiments of the utility model, the refrigerant expansion device 3 is driven and connected to the compressor 2 through a mechanical transmission structure 4 to transfer the torque of the refrigerant expansion device 3 to the compressor 2. In this way, by setting the mechanical transmission structure 4, the torque of the refrigerant expansion device 3 is transferred to the compressor 2 to assist the compressor 2 in compression. Further, there are multiple mechanical transmission structures 4. Specifically, in one embodiment, the refrigerant expansion device 3 has an output shaft, and the compressor 2 has an input shaft. The output shaft is connected to the input shaft through a coupling. In this way, by setting the coupling, the output shaft is connected to the input shaft, so that the refrigerant expansion device 3 assists in driving the compressor 2 to compress. In another embodiment, the mechanical transmission structure 4 also includes a transmission gear set, and the transmission gear set includes two transmission gears meshing with each other. The two transmission gears are respectively arranged on the input shaft and the output shaft, and the torque of the refrigerant expansion device 3 is transferred to the compressor 2.

[0042] In some embodiments of the utility model, the refrigerant circulation device 100 also includes a gas-liquid separator 5 arranged on the refrigerant circulation flow path 1. In this way, by setting the gas-liquid separator 5, the gaseous refrigerant and the liquid refrigerant in the refrigerant circulation flow path 1 are separated to prevent the gaseous refrigerant from flowing into the refrigerant expansion device 3 and affecting the work of the refrigerant expansion device 3, thereby helping to improve the work efficiency of the refrigerant expansion device 3.

[0043] Furthermore, the number of the gas-liquid separators 5 can be one or more, and the utility model does not limit this. Specifically, in the present embodiment, the refrigerant circulation flow path 1 includes a refrigerant main circuit 11 and a multi-stage refrigerant branch circuit 12 connected to the refrigerant main circuit 11. The gas-liquid separators 5 are arranged in plurality, and the two refrigerant branches 12 at the same stage are respectively connected to the liquid phase outlet and the gas phase outlet of the corresponding gas-liquid separator 5, and the refrigerant branch circuit 12 or the refrigerant main circuit 11 at the previous stage is connected to the inlet of the corresponding gas-liquid separator 5. In this way, by arranging a plurality of the gas-liquid separators 5, the gaseous refrigerant and the liquid refrigerant of the refrigerant main circuit 11 or the previous stage can be separated to prevent the gaseous refrigerant in the previous stage from flowing into the refrigerant expansion device 3 on the refrigerant branch circuit 12 of the next stage.

[0044] In some embodiments of the present invention, please refer to Figure 2 , the refrigerant circulation device 100 also includes a cold box 8 and an installation platform 81 arranged on the outside of the cold box 8, wherein the refrigerant expansion device 3 is arranged in the cold box 8, and the compressor 2 is arranged on the installation platform 81. Since the compressor 2 and the cold box 8 are usually produced by different manufacturers, there is a lack of installation position for the compressor 2 on the cold box 8, so that the compressor 2 cannot be installed on the cold box 8, and an additional installation position is required, which will occupy the space of other devices, such as a pipe gallery, etc., and in this embodiment, the installation platform 81 is arranged on the outside of the cold box 8, so that the compressor 2 can be directly installed on the cold box 8, so that the refrigerant circulation device 100 can be centrally arranged for easy management. Furthermore, the installation platform 81 is arranged in the middle and / or upper part of the cold box 8 to reduce the floor space of the refrigerant circulation device 100 and improve the space utilization rate of the refrigerant circulation device 100.

[0045] In addition, to achieve the above-mentioned purpose, the utility model also provides a natural gas liquefaction system, including the above-mentioned refrigerant circulation device 100. It should be noted that the structure of the refrigerant circulation device 100 in the natural gas liquefaction system can refer to the above-mentioned embodiment of the refrigerant circulation device 100, which will not be repeated here; since the above-mentioned refrigerant circulation device 100 is used in the natural gas liquefaction system provided by the utility model, the embodiment of the natural gas liquefaction system provided by the utility model includes all technical solutions of all embodiments of the above-mentioned refrigerant circulation device 100, and the technical effects achieved are also exactly the same, which will not be repeated here.

[0046] The above description is only a preferred embodiment of the present invention, and does not limit the patent scope of the present invention. All equivalent structural changes made under the concept of the present invention using the contents of the specification and drawings of the present invention, or direct / indirect application in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. A refrigerant circulation device for a natural gas liquefaction system, characterized in that: A refrigerant circulation flow path (1) is formed on the refrigerant circulation device, and the refrigerant circulation device comprises: A compressor (2) is provided in the refrigerant circulation flow path (1); and A refrigerant expansion device (3) is arranged in the refrigerant circulation flow path (1), and the refrigerant expansion device (3) is driven and connected to the compressor (2) so that the refrigerant expansion device (3) can assist the compressor (2) in its operation.

2. The refrigerant circulation device according to claim 1, characterized in that: The refrigerant expansion device (3) comprises a piston motor, which is used to enable the refrigerant passing through the piston motor to expand and perform work.

3. The refrigerant circulation device according to claim 1, characterized in that: The refrigerant expansion device (3) is provided in plurality.

4. The refrigerant circulation device according to claim 3, characterized in that: The refrigerant circulation flow path (1) includes a refrigerant main path (11) and a plurality of refrigerant branch paths (12) connected to the refrigerant main path (11); the plurality of refrigerant branch paths (12) are arranged in parallel; the plurality of refrigerant expansion devices (3) are respectively arranged on the plurality of refrigerant branch paths (12); and the plurality of refrigerant expansion devices (3) are driven and connected to the compressor (2).

5. The refrigerant circulation device according to claim 4, characterized in that: The compressor (2) is provided in plurality, and the refrigerant expansion devices (3) located on different refrigerant branches (12) are at least partially driven and connected to different compressors (2).

6. The refrigerant circulation device according to claim 1, characterized in that: The compressor (2) is provided in plurality.

7. The refrigerant circulation device according to claim 1, characterized in that: The refrigerant expansion device (3) is driven and connected to the compressor (2) via a mechanical transmission structure (4) so ​​as to transmit the torque of the refrigerant expansion device (3) to the compressor (2).

8. The refrigerant circulation device according to claim 1, characterized in that: The refrigerant circulation device further comprises a gas-liquid separator (5) arranged on the refrigerant circulation flow path (1).

9. The refrigerant circulation device according to claim 8, characterized in that: The refrigerant circulation flow path (1) comprises a refrigerant trunk line (11) and a multi-stage refrigerant branch line (12) connected to the refrigerant trunk line (11), and a plurality of gas-liquid separators (5) are provided; The two refrigerant branches (12) at the same level are respectively connected to the liquid phase outlet and the gas phase outlet of the corresponding gas-liquid separator (5); The refrigerant branch circuit (12) or the refrigerant trunk circuit (11) at the previous stage is connected to the inlet of the corresponding gas-liquid separator (5).

10. The refrigerant circulation device according to claim 1, characterized in that: The refrigerant circulation device further comprises a cold box (8) and a mounting platform (81) arranged outside the cold box (8); Wherein, the refrigerant expansion device (3) is arranged in the cold box (8), and the compressor (2) is arranged on the installation platform (81).

11. A natural gas liquefaction system, characterized in that: It comprises a refrigerant circulation device as described in any one of claims 1 to 10.

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