Liquefaction device and liquefaction method

Abstract

The present invention improves the efficiency of liquefaction of a feed gas. This liquefaction device includes: a feed pipeline through which a feed gas flows; a feed-cooling part by which the feed gas being flowing in the feed pipeline is cooled with a refrigerant; a magnetic refrigeration part which is disposed downstream from the feed-cooling part along the feed-gas flow inside the feed pipeline and by which the cooled feed gas is cooled with a magnetic body to liquefy the feed gas; and a magnetic-body-cooling part in which the magnetic body that has cooled the feed gas is cooled with a refrigerant.

Description

Liquefaction device and liquefaction method

[0001] The present disclosure relates to a liquefaction device and a liquefaction method.

[0002] There are known techniques for liquefying and storing a source gas such as hydrogen gas. For example, Non-Patent Document 1 describes that the source hydrogen gas is liquefied by cooling it with liquid nitrogen and expanding it using a Joule-Thomson valve.

[0003] Seiji Yamashita et al., "Development of Hydrogen Liquefaction Storage System," Journal of Japan Society of Energy and Resources, Vol. 37, No. 4

[0004] However, since the liquefaction of gas using a Joule-Thomson valve utilizes the principle of isenthalpic expansion, there is a risk of low liquefaction efficiency. Therefore, there is a demand for improving the liquefaction efficiency of the raw gas.

[0005] An object of the present disclosure is to provide a liquefaction apparatus and a liquefaction method that can improve the efficiency of liquefying a raw material gas.

[0006] The liquefaction apparatus according to the present disclosure includes a raw material pipe through which a raw material gas flows, a raw material cooling unit that cools the raw material gas flowing through the raw material pipe with a refrigerant, a magnetic refrigeration unit that is provided downstream of the raw material cooling unit in the flow of the raw material gas within the raw material pipe and cools the cooled raw material gas with a magnetic material to liquefy the raw material gas, and a magnetic material cooling unit that cools the magnetic material that has cooled the raw material gas with the refrigerant.

[0007] The liquefaction method according to the present disclosure includes the steps of: cooling a raw material gas with a refrigerant; cooling the raw material gas cooled by the refrigerant with a magnetic material to liquefy the raw material gas; and cooling the magnetic material that has cooled the raw material gas with the refrigerant.

[0008] According to the present disclosure, the efficiency of liquefying a raw material gas can be improved.

[0009] Fig. 1 is a schematic diagram of a liquefaction apparatus according to this embodiment. Fig. 2 is a schematic diagram illustrating an example of a refrigeration cycle of a magnetic refrigeration unit. Fig. 3 is a flowchart illustrating a method for liquefying a raw material gas.

[0010] Preferred embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings. Note that the present disclosure is not limited to these embodiments, and when there are multiple embodiments, the present disclosure also includes configurations in which the respective embodiments are combined.

[0011] (Liquefaction Apparatus) FIG. 1 is a schematic diagram of a liquefaction apparatus according to this embodiment. The liquefaction apparatus 1 according to this embodiment is an apparatus for liquefying a raw material gas HG. Hereinafter, the liquefied raw material gas HG will be referred to as liquid HL. The raw material gas HG may be any substance, such as hydrogen, oxygen, or natural gas, but in this embodiment, hydrogen is used as the raw material gas HG. Therefore, the liquid HL in this embodiment is liquid hydrogen. Furthermore, the raw material gas HG and the liquid HL may be used for any purpose, such as rocket fuel.

[0012] As shown in FIG. 1 , the liquefaction apparatus 1 includes a raw material piping 10, a raw material supply unit 12, a liquid storage unit 14, nitrogen piping 20, 22, a nitrogen supply unit 24, a refrigerant piping 30, a refrigerant compression unit 32, a refrigerant cooling unit 34, refrigerant expansion units 36, 38, a raw material cooling unit 40, a raw material expansion unit 48, a magnetic refrigeration unit 50, a magnetic material cooling unit 60, and a control device 100.

[0013] The control device 100 is a controller that controls each mechanism of the liquefaction device 1. The control device 100 controls each mechanism of the liquefaction device 1, causing the liquefaction device 1 to liquefy the raw material gas HG and produce the liquid HL. The control device 100 may be, for example, a computer having an arithmetic circuit such as a CPU (Central Processing Unit), a memory, etc. The control content of the control device 100 will be described later.

[0014] (Liquefaction Line) The raw material pipe 10, the raw material supply unit 12, the liquid storage unit 14, the raw material cooling unit 40, the raw material expansion unit 48, and the magnetic refrigeration unit 50 constitute a liquefaction line that liquefies the raw material gas HG. The raw material pipe 10 is a pipe through which the raw material gas HG and the liquid HL pass. The raw material supply unit 12 is a mechanism connected to the raw material pipe 10 and supplies the raw material gas HG to the raw material pipe 10. The raw material supply unit 12 may be, for example, a container in which the raw material gas HG is stored. The liquid storage unit 14 is a mechanism connected to the raw material pipe 10 and supplies the liquid HL liquefied in the raw material pipe 10. The liquid storage unit 14 may be, for example, a container in which the liquid HL is stored. In this embodiment, one end of the raw material pipe 10 is connected to the raw material supply unit 12, and the other end of the raw material pipe 10 is connected to the liquid storage unit 14. Hereinafter, the direction from the raw material supply unit 12 to the liquid reservoir 14 in the raw material pipe 10, that is, the direction in which the raw material gas HG and the liquid HL flow in the raw material pipe 10, will be referred to as the raw material flow direction DH.

[0015] The raw material cooling section 40, the raw material expansion section 48, and the magnetic refrigeration section 50 will be described later.

[0016] (Nitrogen Line) The nitrogen pipes 20, 22 and the nitrogen supply unit 24 constitute a nitrogen line that conducts nitrogen for cooling the raw material gas HG. The nitrogen pipe 20 is a pipe through which liquid nitrogen NL passes. The nitrogen supply unit 24 is a mechanism that is connected to the nitrogen pipe 20 and supplies liquid nitrogen NL to the nitrogen pipe 20. The nitrogen supply unit 24 may be, for example, a container that stores liquid nitrogen NL. In this embodiment, one end of the nitrogen pipe 20 is connected to the nitrogen supply unit 24, and the other end of the nitrogen pipe 20 is connected to a third raw material cooling unit 44, which will be described later. Liquid nitrogen NL is supplied to the third raw material cooling unit 44 from the nitrogen pipe 20.

[0017] Nitrogen pipe 22 is a pipe through which nitrogen gas NG, which is vaporized liquid nitrogen NL, passes. Nitrogen pipe 22 is connected to third raw material cooling section 44. That is, at least a portion of the liquid nitrogen NL is vaporized in third raw material cooling section 44 to become nitrogen gas NG, and the nitrogen gas NG is introduced into nitrogen pipe 22.

[0018] In this embodiment, the source gas HG is cooled by the liquid nitrogen NL and nitrogen gas NG flowing through the nitrogen line, but the nitrogen line is not an essential component. That is, cooling of the source gas HG by the liquid nitrogen NL and nitrogen gas NG is not essential. The source gas HG may be cooled by at least the refrigerant C described below.

[0019] (Refrigerant Line) The refrigerant pipe 30, the refrigerant compression section 32, the refrigerant cooling section 34, and the refrigerant expansion sections 36 and 38 constitute a refrigerant line that conducts a refrigerant C for cooling the raw material gas HG. The refrigerant C may be any substance that can cool the raw material gas HG, but in this embodiment, it is hydrogen.

[0020] The refrigerant piping 30 is a piping through which the refrigerant C passes. The refrigerant compression unit 32 is connected to the refrigerant piping 30. The refrigerant compression unit 32 increases the temperature of the refrigerant C by compressing the refrigerant C. More specifically, the refrigerant compression unit 32 compresses the refrigerant C after cooling the raw material gas HG (the refrigerant C after heat exchange in the raw material cooling unit 40 described below). The refrigerant compression unit 32 may be any mechanism capable of compressing the refrigerant C, but in this embodiment, a compression turbine that compresses the refrigerant C is used.

[0021] The refrigerant piping 30 is a loop-shaped pipe through which the refrigerant C circulates. That is, one end of the refrigerant piping 30 is connected to an outlet 32A of the refrigerant compression section 32, and the other end is connected to an inlet 32B of the refrigerant compression section 32. The outlet 32A is the outlet from which the refrigerant C compressed in the refrigerant compression section 32 is discharged, and the inlet 32B is the inlet through which the refrigerant C is introduced into the refrigerant compression section 32. Hereinafter, the direction from the outlet 32A to the inlet 32B in the refrigerant piping 30, i.e., the direction in which the refrigerant C flows within the refrigerant piping 30, is referred to as the refrigerant flow direction DC. That is, the start point of the refrigerant flow direction DC is the outlet 32A, and the end point of the refrigerant flow direction DC is the inlet 32B.

[0022] The refrigerant cooling unit 34 is a heat exchanger that cools the refrigerant C flowing through the refrigerant pipe 30. The refrigerant cooling unit 34 is located closer to the refrigerant flow direction DC than the refrigerant compression unit 32 (downstream of the flow of the refrigerant C) and in contact with the refrigerant pipe 30. Therefore, the refrigerant cooling unit 34 cools the refrigerant C flowing through the refrigerant pipe 30 after being compressed by the refrigerant compression unit 32. Note that the term "contact" here does not necessarily mean direct contact, but also includes contact via another member (solid, liquid, or gas), and this also applies hereinafter. That is, for example, the refrigerant cooling unit 34 may be in direct contact with the refrigerant pipe 30 at a position closer to the refrigerant flow direction DC than the refrigerant compression unit 32, or may be in contact via another member (solid, liquid, or gas).

[0023] The refrigerant cooling unit 34 may use any method for cooling the refrigerant C. For example, the refrigerant cooling unit 34 may have a coolant pipe through which a coolant (e.g., water) flows and a member that contacts the coolant pipe and the refrigerant pipe 30, and may cool the refrigerant C by exchanging heat between the coolant flowing through the coolant pipe and the refrigerant C flowing through the refrigerant pipe 30.

[0024] The refrigerant expansion section 36 is connected to the refrigerant pipe 30 on the refrigerant flow direction DC side of the refrigerant compression section 32, and in this embodiment, on the refrigerant flow direction DC side of the refrigerant cooling section 34. The refrigerant expansion section 36 expands the refrigerant C flowing through the refrigerant pipe 30, thereby cooling the refrigerant C. The refrigerant compression section 32 may be any mechanism capable of expanding the refrigerant C, and may use, for example, a two-phase expansion turbine or a Joule-Thomson valve, but in this embodiment, a Joule-Thomson valve is used.

[0025] The refrigerant expansion section 36 is connected in series to the refrigerant pipe 30. That is, an inlet of the refrigerant expansion section 36 (an inlet into which the refrigerant C is introduced) is connected to the refrigerant flow direction DC side of the position where the refrigerant compression section 32 (refrigerant cooling section 34) is provided on the refrigerant pipe 30. An outlet of the refrigerant expansion section 36 (an outlet from which the refrigerant C is discharged) is connected to the refrigerant pipe 30 on the opposite side (upstream side) from the position where the refrigerant compression section 32 is provided in the refrigerant flow direction DC.

[0026] The refrigerant expansion section 38 is connected to the refrigerant pipe 30 on the refrigerant flow direction DC side of the refrigerant compression section 32, and in this embodiment, on the refrigerant flow direction DC side of the refrigerant cooling section 34. The refrigerant expansion section 38 expands the refrigerant C flowing through the refrigerant pipe 30, thereby cooling the refrigerant C. The refrigerant expansion section 38 may be any mechanism capable of expanding the refrigerant C, and may be, for example, a two-phase expansion turbine or a Joule-Thomson valve, but in this embodiment, a two-phase expansion turbine is used.

[0027] The refrigerant expansion section 38 is connected in parallel (branched) to the refrigerant pipe 30. The inlet of the refrigerant expansion section 38 (the inlet through which refrigerant C is introduced) is connected to a location in the refrigerant flow direction DC between the position of the refrigerant cooling section 34 on the refrigerant pipe 30 and the position of the refrigerant expansion section 36 (more specifically, between the second feedstock cooling section 42 and the fourth feedstock cooling section 46, which will be described later). The outlet of the refrigerant expansion section 38 (the outlet from which refrigerant C is discharged) is connected to a location in the refrigerant flow direction DC between the position of the refrigerant expansion section 36 on the refrigerant pipe 30 and the position of the refrigerant compression section 32 (more specifically, between the fourth feedstock cooling section 46 and the second feedstock cooling section 42, which will be described later).

[0028] (Feedstock cooling section) The feedstock cooling section 40 is a mechanism that cools the feedstock gas HG flowing through the feedstock piping 10 by using a refrigerant C. Any method for cooling the feedstock gas HG by the feedstock cooling section 40 may be used, but in this embodiment, the feedstock gas HG is cooled by heat exchange between the refrigerant C flowing through the refrigerant piping 30 and the feedstock gas HG flowing through the feedstock piping 10. That is, the feedstock cooling section 40 in this embodiment is a heat exchanger.

[0029] The raw material cooling unit 40 may include any number of raw material cooling units (heat exchangers), but in this embodiment, the raw material cooling unit 40 includes a first raw material cooling unit 41, a second raw material cooling unit 42, a third raw material cooling unit 44, and a fourth raw material cooling unit 46. Each raw material cooling unit will be described below.

[0030] (First raw material cooling section) The first raw material cooling section 41 is provided at a position closer to the raw material flow direction DH (downstream of the flow of the raw material gas HG) than the raw material supply section 12, and in contact with the raw material piping 10. The first raw material cooling section 41 is also provided at a position in contact with the nitrogen piping 22. The first raw material cooling section 41 cools the raw material gas HG by exchanging heat between the raw material gas HG flowing through the raw material piping 10 and the nitrogen gas NG flowing through the nitrogen piping 22.

[0031] The first raw material cooling section 41 preferably cools the raw material gas HG to a temperature of, for example, −50° C. to −100° C. or lower.

[0032] (Second Feedstock Cooling Section) The second feedstock cooling section 42 is provided at a position closer to the feedstock flow direction DH than the feedstock supply section 12 and in contact with the feedstock piping 10. The second feedstock cooling section 42 is also provided at a position in contact with the refrigerant piping 30. The second feedstock cooling section 42 cools the feedstock gas HG by exchanging heat between the feedstock gas HG flowing through the feedstock piping 10 and the refrigerant C flowing through the refrigerant piping 30.

[0033] More specifically, in this embodiment, second feedstock cooling section 42 is provided closer to the feedstock flow direction DH than first feedstock cooling section 41. Second feedstock cooling section 42 is also provided in a location on refrigerant pipe 30, in the refrigerant flow direction DC, between the location of fourth feedstock cooling section 46 and the location of refrigerant compression section 32. Therefore, second feedstock cooling section 42 further cools the feedstock gas HG, which has been cooled in first feedstock cooling section 41, by refrigerant C flowing through refrigerant pipe 30 from fourth feedstock cooling section 46 in the refrigerant flow direction DC.

[0034] In this embodiment, second feedstock cooling unit 42 is provided in refrigerant flow direction DC at a location on refrigerant pipe 30 between the location of refrigerant cooling unit 34 and the location of fourth feedstock cooling unit 46. Therefore, second feedstock cooling unit 42 also cools refrigerant C that has been cooled by refrigerant cooling unit 34 using refrigerant C flowing through refrigerant pipe 30 from fourth feedstock cooling unit 46 in refrigerant flow direction DC.

[0035] The second raw material cooling section 42 preferably cools the raw material gas HG to a temperature of, for example, −100° C. to −150° C. or lower.

[0036] (Third Feedstock Cooling Section) The third feedstock cooling section 44 is connected to the nitrogen pipe 20 and stores the liquid nitrogen NL supplied from the nitrogen pipe 20. A portion of the feedstock pipe 10 closer to the feedstock flow direction DH than the second feedstock cooling section 42 passes through the third feedstock cooling section 44. The third feedstock cooling section 44 exchanges heat between the stored liquid nitrogen NL and the feedstock gas HG passing through the feedstock pipe 10 within the third feedstock cooling section 44, thereby further cooling the feedstock gas HG cooled in the second feedstock cooling section 42 with the liquid nitrogen NL. The liquid nitrogen NL, whose temperature has been increased by the heat exchange, is vaporized and discharged to the nitrogen pipe 22 as nitrogen gas NG.

[0037] In this embodiment, the feed pipe 10 is connected to an ortho-para conversion catalyst 44A in the third feed cooling section 44. The ortho-para conversion catalyst 44A is a catalyst that promotes the conversion of ortho-hydrogen to para-hydrogen (ortho-para conversion). The ortho-hydrogen contained in the feed gas HG passing through the feed pipe 10 in the third feed cooling section 44 is converted to para-hydrogen by coming into contact with the ortho-para conversion catalyst 44A. Furthermore, the feed gas HG generates heat during ortho-para conversion, but the temperature rise can be suppressed by cooling it with liquid nitrogen NL.

[0038] The third raw material cooling section 44 preferably cools the raw material gas HG to a temperature of, for example, −180° C. or lower.

[0039] (Fourth feedstock cooling section) The fourth feedstock cooling section 46 is provided at a position closer to the feedstock flow direction DH than the feedstock supply section 12 and in contact with the feedstock piping 10. The fourth feedstock cooling section 46 is also provided at a position in contact with the refrigerant piping 30. The fourth feedstock cooling section 46 cools the feedstock gas HG by exchanging heat between the feedstock gas HG flowing through the feedstock piping 10 and the refrigerant C flowing through the refrigerant piping 30.

[0040] More specifically, in this embodiment, fourth feedstock cooling section 46 is provided closer to the feedstock flow direction DH than third feedstock cooling section 44. Furthermore, fourth feedstock cooling section 46 is provided at a location on refrigerant pipe 30, in refrigerant flow direction DC, between the position where refrigerant expansion section 36 is provided and the position where second feedstock cooling section 42 is provided. Therefore, fourth feedstock cooling section 46 further cools the feedstock gas HG, which has been cooled in third feedstock cooling section 44, by refrigerant C flowing through refrigerant pipe 30 from refrigerant expansion section 36 in refrigerant flow direction DC.

[0041] In this embodiment, fourth feedstock cooling section 46 is provided in refrigerant flow direction DC at a location on refrigerant pipe 30 between the location of second feedstock cooling section 42 and the location of refrigerant expansion section 36. Therefore, fourth feedstock cooling section 46 also cools refrigerant C that has undergone heat exchange in second feedstock cooling section 42 using refrigerant C flowing through refrigerant pipe 30 from refrigerant expansion section 36 in refrigerant flow direction DC.

[0042] In this embodiment, the feed pipe 10 is connected to the ortho-para conversion catalyst 46A even at a position where it contacts the fourth feed cooling section 46. The ortho-para conversion catalyst 46A is a catalyst that promotes the conversion of ortho-hydrogen to para-hydrogen (ortho-para conversion). The ortho-hydrogen contained in the feed gas HG passing through the feed pipe 10 is converted to para-hydrogen by contacting the ortho-para conversion catalyst 46A. Furthermore, the feed gas HG generates heat during ortho-para conversion, but by being cooled by the fourth feed cooling section 46, the temperature rise can be suppressed.

[0043] The fourth raw material cooling section 46 preferably cools the raw material gas HG to a temperature of, for example, −240° C. or higher and −220° C. or lower.

[0044] (Feedstock expansion section) The feedstock expansion section 48 is connected to the feedstock piping 10 closer to the feedstock flow direction DH than the feedstock cooling section 40, and in this embodiment, closer to the fourth feedstock cooling section 46 in the feedstock flow direction DH. The feedstock expansion section 48 expands the feedstock gas HG flowing through the feedstock piping 10 and cooled in the feedstock cooling section 40, thereby vaporizing at least a portion of the feedstock gas HG and producing liquid HL. The feedstock expansion section 48 may be any mechanism capable of expanding the feedstock gas HG, such as a two-phase expansion turbine or a Joule-Thomson valve, but in this embodiment, a two-phase expansion turbine is used.

[0045] The feedstock expansion section 48 is connected in series to the feedstock piping 10. That is, the inlet of the feedstock expansion section 48 (the inlet through which the feedstock gas HG is introduced) is connected closer to the feedstock flow direction DH than the position where the feedstock cooling section 40 (fourth feedstock cooling section 46 in this embodiment) is provided. The outlet of the feedstock expansion section 48 (the outlet from which the feedstock gas HG and liquid HL are discharged) is connected on the opposite side (upstream side) from the position where the magnetic refrigeration section 50 (described later) is provided in the feedstock flow direction DH.

[0046] However, the raw material expansion section 48 is not an essential component. For example, the liquefaction apparatus 1 may not have the raw material expansion section 48, and the raw material gas HG cooled in the raw material cooling section 40 may be liquefied only by the magnetic refrigeration section 50 described below.

[0047] (Magnetic Refrigeration Unit) The magnetic refrigeration unit 50 is provided closer to the raw material flow direction DH than the raw material cooling unit 40, at a position where it contacts the raw material piping 10. The magnetic refrigeration unit 50 uses a magnetic body 54 (see FIG. 2 described later) to cool the raw material gas HG flowing through the raw material piping 10 after being cooled by the raw material cooling unit 40, and liquefies the raw material gas HG to produce a liquid HL. That is, the magnetic refrigeration unit 50 liquefies the raw material gas HG by magnetic refrigeration.

[0048] More specifically, in this embodiment, the magnetic refrigeration unit 50 is provided at a position closer to the raw material flow direction DH than the raw material expansion unit 48, and in contact with the raw material piping 10. The magnetic refrigeration unit 50 uses a magnetic body 54 to cool the raw material gas HG, which remains vaporized without being liquefied after being expanded in the raw material expansion unit 48, and liquefies the raw material gas HG to produce a liquid HL.

[0049] The magnetic refrigeration unit 50 preferably cools the liquid HL (raw material gas HG) to a temperature of, for example, −250° C. or lower.

[0050] The liquid HL produced by the magnetic refrigeration unit 50 is introduced from the raw material pipe 10 into the liquid reservoir 14 and is stored in the liquid reservoir 14 .

[0051] (Magnetic body cooling unit) The magnetic body cooling unit 60 is a mechanism that cools the magnetic body 54 of the magnetic refrigeration unit 50 by using the refrigerant C. The magnetic body cooling unit 60 cools the magnetic body 54 by exchanging heat between the refrigerant C flowing through the refrigerant pipe 30 and the magnetic body 54.

[0052] The magnetic material cooling unit 60 is provided at a position where it contacts the magnetic material 54. Furthermore, the magnetic material cooling unit 60 is provided at a location on the refrigerant pipe 30, in the refrigerant flow direction DC, between the position where the refrigerant expansion unit 36 ​​is provided and the position where the fourth raw material cooling unit 46 is provided. Therefore, the magnetic material cooling unit 60 cools the magnetic material 54 with the refrigerant C flowing through the refrigerant pipe 30 from the refrigerant expansion unit 36 ​​in the refrigerant flow direction DC.

[0053] In this way, the magnetic material cooling section 60 cools the magnetic material 54 with the refrigerant C cooled in the refrigerant expansion section 36. Therefore, the magnetic material 54 can be cooled with the refrigerant C that has been cooled to the lowest temperature in the refrigerant line. In this embodiment, the refrigerant C that has cooled the magnetic material 54 pre-cools the raw material gas HG in the raw material cooling section 40. More specifically, the refrigerant C that has cooled the magnetic material 54 flows through the refrigerant line in the order of the fourth raw material cooling section 46 and the second raw material cooling section 42. Therefore, the temperature of the refrigerant C decreases in the order of the second raw material cooling section 42, the fourth raw material cooling section 46, and the magnetic material cooling section 60. This allows the raw material gas HG and the magnetic material 54 to be efficiently cooled by the refrigerant C.

[0054] (Refrigeration Cycle of Magnetic Refrigeration Unit) A specific example of the refrigeration cycle of the magnetic refrigeration unit 50 will be described. FIG. 2 is a schematic diagram illustrating an example of the refrigeration cycle of the magnetic refrigeration unit. In the example of FIG. 2, the magnetic refrigeration unit 50 has a shaft 52, a magnetic body 54, and a magnet 56. The shaft 52 is a shaft-shaped member. The magnetic body 54 is a member whose temperature changes with changes in magnetic flux density. The magnetic body 54 may be made of any material whose temperature changes with changes in magnetic flux density, such as a gadolinium compound. The magnetic body 54 is attached to the shaft 52 so as to be movable in the axial direction. For example, the control device 100 may control a drive mechanism that moves the magnetic body 54 in the axial direction to move the magnetic body 54.

[0055] The magnet 56 generates a magnetic field. The magnet 56 may be an electromagnet or a permanent magnet. In the example shown in Fig. 2, the magnet 56 is annular and is disposed so as to surround the shaft portion 52.

[0056] As shown in step S1 of FIG. 2 , when cooling the magnetic body 54, a magnetic field is applied to the magnetic body 54 by the magnet 56. The temperature of the magnetic body 54 increases when the magnetic field is applied. Note that any method may be used to apply the magnetic field from the magnet 56 to the magnetic body 54. For example, if the magnet 56 is an electromagnet, the control device 100 may apply a current to the magnet 56 to generate a magnetic field from the magnet 56, and apply the magnetic field to the magnetic body 54. Alternatively, if the magnet 56 is a permanent magnet, the magnetic body 54 may be positioned inside the inner circumferential surface of the magnet 56, and a magnetic field may be applied to the magnetic body 54.

[0057] Then, as shown in step S2, the magnetic body 54, whose temperature has increased due to the application of the magnetic field, is brought into contact with the magnetic body cooling unit 60 (refrigerant piping 30). As a result, heat is exchanged between the magnetic body 54 and the refrigerant C in the magnetic body cooling unit 60, and the magnetic body 54 is cooled (heat is discharged).

[0058] Thereafter, as shown in step S3, the application of the magnetic field from the magnet 56 to the magnetic body 54 is stopped. This causes the magnetic body 54 to further cool. Note that any method for stopping the application of the magnetic field to the magnetic body 54 may be used. For example, if the magnet 56 is an electromagnet, the application of the magnetic field to the magnetic body 54 may be stopped by having the control device 100 stop applying current to the magnet 56. Alternatively, if the magnet 56 is a permanent magnet, the application of the magnetic field to the magnetic body 54 may be stopped by moving the magnetic body 54 away from the magnet 56. The magnetic body 54, cooled by stopping the application of the magnetic field, comes into contact with the raw material pipe 10 and cools the raw material gas HG in the raw material pipe 10, thereby liquefying the raw material gas HG. If the temperature of the magnetic body 54 rises due to the liquefaction of the raw material gas HG, the process returns to step S1, and the same refrigeration cycle is repeated.

[0059] However, the refrigeration cycle of the magnetic refrigeration unit 50 is not limited to the one shown in the example of Fig. 2. For example, in the example of Fig. 2, the magnetic body 54 is configured to be movable along the shaft portion 52, but this is not limited thereto, and the position of the magnetic body 54 may be fixed. Also, for example, the magnetic body 54 cools the source gas HG by contacting the outer circumferential surface of the source pipe 10, but this is not limited thereto, and the magnetic body 54 may be inserted into the source pipe 10 and directly contact the source gas HG in the source pipe 10 to cool the source gas HG.

[0060] (Liquefaction Method) A flow chart will be described below of the method for liquefying the raw material gas HG using the above-described liquefaction apparatus 1. Fig. 3 is a flowchart for explaining the method for liquefying the raw material gas.

[0061] As shown in FIG. 3 , in this method, the raw material cooling unit 40 cools the raw material gas HG with the refrigerant C (step S10). In this step, the controller 100 controls the raw material supply unit 12 to supply the raw material gas HG into the raw material piping 10. In this case, for example, the controller 100 may control the valve of the raw material supply unit 12 to supply the raw material gas HG from the raw material supply unit 12. The controller 100 also controls the nitrogen supply unit 24 to supply liquid nitrogen NL into the nitrogen piping 20. In this case, for example, the controller 100 may control the valve of the nitrogen supply unit 24 to supply the liquid nitrogen NL from the nitrogen supply unit 24. The controller 100 also operates the refrigerant compression unit 32, the refrigerant cooling unit 34, and the refrigerant expansion units 36 and 38 to circulate the refrigerant C through the refrigerant piping 30. As a result, the raw material gas HG flows through the raw material piping 10 along the raw material flow direction DH while being cooled by the raw material cooling unit 40. Specifically, the feed gas HG is cooled in the first feed cooling section 41 by nitrogen gas NG flowing through the nitrogen pipe 22. The feed gas HG cooled in the first feed cooling section 41 is further cooled in the second feed cooling section 42 by refrigerant C flowing through the refrigerant pipe 30. The feed gas HG cooled in the second feed cooling section 42 is then cooled by liquid nitrogen NL while undergoing ortho-para conversion in the third feed cooling section 44. The feed gas HG cooled in the third feed cooling section 44 is then cooled in the fourth feed cooling section 46 by refrigerant C flowing through the refrigerant pipe 30 while undergoing ortho-para conversion.

[0062] Next, in this method, the feed gas HG cooled in the feed cooling section 40 is expanded in the feed expansion section 48 to further cool the feed gas HG (step S12). If the feed expansion section 48 is a two-phase turbine, the control device 100 operates the feed expansion section 48 to expand the feed gas HG. Alternatively, if the feed expansion section 48 is a Joule-Thomson valve, for example, the feed gas HG expands by passing through the feed expansion section 48, which is also a Joule-Thomson valve. At least a portion of the feed gas HG expanded in the feed expansion section 48 is liquefied to become the feed liquid HL.

[0063] Next, in this method, the raw material gas HG after expansion in the raw material expansion section 48 is further cooled by the magnetic refrigeration section 50 (step S14). The control device 100 brings the magnetic body 54 of the magnetic refrigeration section 50 into contact with the raw material pipe 10, thereby causing heat exchange between the magnetic body 54 and the raw material gas HG, thereby cooling the raw material gas HG. At least a portion of the raw material gas HG cooled in the magnetic refrigeration section 50 is liquefied into a liquid HL. In this embodiment, it is preferable to liquefy all of the raw material gas HG that remains vaporized even after expansion in the raw material expansion section 48.

[0064] Through the above steps, the source gas HG is liquefied to produce the liquid HL. The liquefaction apparatus 1 cools the magnetic body 54 after cooling the source gas HG in the cycle as described in steps S1, S2, and S3 of FIG. 2. That is, after cooling the source gas HG, the magnetic body 54 is heated by applying a magnetic field by the magnet 56, and then the heat is released (cooled) by the refrigerant C, and the application of the magnetic field is stopped, thereby further cooling the magnetic body 54. The magnetic body 54 cooled in this cycle is reused to cool the source gas HG.

[0065] As described above, in this embodiment, the raw gas HG pre-cooled with the refrigerant C is magnetically refrigerated in the magnetic refrigeration unit 50 and liquefied. According to this embodiment, the use of magnetic refrigeration can improve the liquefaction efficiency of the raw gas HG. Furthermore, in this embodiment, the magnetic body 54 of the magnetic refrigeration unit 50 is cooled by the refrigerant C used to pre-cool the raw gas HG. Therefore, it is possible to efficiently perform the refrigeration cycle of the magnetic body 54 and pre-cooling of the raw gas HG. Furthermore, in this embodiment, the raw gas HG pre-cooled with the refrigerant C is expanded in the raw material expansion unit 48 and then cooled in the magnetic refrigeration unit 50. As described above, by liquefying the raw gas HG in a two-stage process of expansion and magnetic refrigeration, the liquefaction efficiency can be further improved.

[0066] (Effects) As described above, the liquefaction apparatus 1 according to the first aspect of the present disclosure includes the raw material pipe 10 through which the raw material gas HG flows, the raw material cooling unit 40 that cools the raw material gas HG flowing through the raw material pipe 10 with the refrigerant C, the magnetic refrigeration unit 50 that is provided downstream of the flow of the raw material gas HG within the raw material pipe 10 (on the raw material flow direction DH side) of the raw material cooling unit 40 and that liquefies the raw material gas HG by cooling the cooled raw material gas HG with the magnetic material 54, and the magnetic material cooling unit 60 that cools the magnetic material 54 that has cooled the raw material gas HG with the refrigerant C. According to the present disclosure, the use of magnetic refrigeration improves the liquefaction efficiency of the raw material gas HG, while the refrigeration cycle of the magnetic material 54 and the pre-cooling of the raw material gas HG can be efficiently performed by cooling the magnetic material 54 of the magnetic refrigeration unit 50 with the refrigerant C used to pre-cool the raw material gas HG.

[0067] The liquefaction apparatus 1 according to a second aspect of the present disclosure is the liquefaction apparatus according to the first aspect, and further includes a feed expansion section 48 that is provided between the feed cooling section 40 and the magnetic refrigeration section 50 in the flow of the feed gas HG in the feed pipe 10, and that expands the feed gas HG cooled by the refrigerant C to liquefy a portion of the feed gas HG. According to the present disclosure, the liquefaction efficiency can be more suitably improved by liquefying the feed gas HG in a two-stage process of expansion and magnetic refrigeration.

[0068] A liquefaction apparatus 1 according to a third aspect of the present disclosure is the liquefaction apparatus according to the second aspect, and uses a two-phase expansion turbine or a Joule-Thomson valve as the feed expansion section 48. According to the present disclosure, the feed gas HG cooled by the refrigerant C can be appropriately expanded, thereby more suitably improving the liquefaction efficiency.

[0069] A liquefaction apparatus 1 according to a fourth aspect of the present disclosure is the liquefaction apparatus according to any one of the first to third aspects, further including a refrigerant expansion section 36 that cools the refrigerant C by expansion. The magnetic material cooling section 60 cools the magnetic material 54 with the refrigerant C cooled by the refrigerant expansion section 36, and the raw material cooling section 40 cools the raw material gas HG with the refrigerant C after cooling the magnetic material 54. According to the present disclosure, the refrigeration cycle of the magnetic material 54 and the pre-cooling of the raw material gas HG can be efficiently performed.

[0070] The liquefaction apparatus 1 according to a fifth aspect of the present disclosure is the liquefaction apparatus according to the fourth aspect, and further includes a refrigerant compression unit 32 that compresses the refrigerant C obtained by cooling the raw material gas HG, and a refrigerant cooling unit 34 that cools the compressed refrigerant C. According to the present disclosure, the magnetic body 54 is cooled, the raw material gas HG is pre-cooled, and then the refrigerant C is compressed to release heat, thereby enabling efficient cooling by the refrigerant C.

[0071] A liquefaction apparatus 1 according to a sixth aspect of the present disclosure is the liquefaction apparatus according to any one of the first to fifth aspects, in which the raw material gas HG is hydrogen gas. According to the present disclosure, hydrogen can be appropriately liquefied.

[0072] A liquefaction method according to a seventh aspect of the present disclosure includes the steps of cooling a raw material gas HG with a refrigerant C, liquefying the raw material gas HG by cooling the raw material gas HG cooled by the refrigerant C with a magnetic material 54, and cooling the magnetic material 54 that has cooled the raw material gas HG with the refrigerant C. According to the present disclosure, the liquefaction efficiency of the raw material gas HG can be improved, while the refrigeration cycle of the magnetic material 54 and the pre-cooling of the raw material gas HG can be efficiently performed.

[0073] A liquefaction method according to an eighth aspect of the present disclosure is the liquefaction method according to the seventh aspect, further comprising a step of expanding the raw material gas HG cooled by the refrigerant C to liquefy a portion of the raw material gas HG, and in the step of liquefying the raw material gas HG by the magnetic body 54, the raw material gas HG that was not liquefied by the expansion is liquefied. According to the present disclosure, liquefaction efficiency can be more suitably improved by liquefying the raw material gas HG in a two-stage process of expansion and magnetic refrigeration.

[0074] Although the embodiments of the present disclosure have been described above, the embodiments are not limited to the contents of these embodiments. Furthermore, the above-described components include those that can be easily imagined by a person skilled in the art, those that are substantially the same, and those that are within the so-called equivalent range. Furthermore, the above-described components can be combined as appropriate. Furthermore, various omissions, substitutions, or modifications of the components can be made without departing from the spirit of the above-described embodiments.

[0075] REFERENCE SIGNS LIST 1 Liquefaction device 10 Raw material pipe 12 Raw material supply section 14 Liquid storage section 20, 22 Nitrogen pipe 24 Nitrogen supply section 30 Refrigerant pipe 32 Refrigerant compression section 34 Refrigerant cooling section 36, 38 Refrigerant expansion section 40 Raw material cooling section 48 Raw material expansion section 50 Magnetic refrigeration section 54 Magnetic material 60 Magnetic material cooling section C Refrigerant HG Raw material gas HL Liquid

Claims

1. A liquefaction apparatus comprising: a raw material piping through which a raw material gas flows; a raw material cooling unit that cools the raw material gas flowing in the raw material piping with a refrigerant; a magnetic refrigeration unit that is provided downstream of the flow of the raw material gas in the raw material piping from the raw material cooling unit and cools the cooled raw material gas with a magnetic material to liquefy the raw material gas; and a magnetic material cooling unit that cools the magnetic material that has cooled the raw material gas with the refrigerant.

2. A liquefaction apparatus as described in claim 1, further comprising a raw material expansion section provided between the raw material cooling section and the magnetic refrigeration section in the flow of the raw material gas within the raw material piping, which expands the raw material gas cooled by the refrigerant and liquefies a portion of the raw material gas.

3. The liquefaction apparatus according to claim 2, wherein the feed expansion section is a two-phase expansion turbine or a Joule-Thomson valve.

4. A liquefaction apparatus as described in any one of claims 1 to 3, further comprising a refrigerant expansion section which expands and cools the refrigerant, wherein the magnetic material cooling section cools the magnetic material with the refrigerant cooled by the refrigerant expansion section, and the raw material cooling section cools the raw material gas with the refrigerant after cooling the magnetic material.

5. The liquefaction apparatus according to claim 4, further comprising: a refrigerant compression section for compressing the refrigerant that has cooled the raw material gas; and a refrigerant cooling section for cooling the compressed refrigerant.

6. A liquefaction apparatus according to any one of claims 1 to 3, wherein the raw material gas is hydrogen gas.

7. A liquefaction method comprising the steps of: cooling a raw material gas with a refrigerant; cooling the raw material gas cooled by the refrigerant with a magnetic material to liquefy the raw material gas; and cooling the magnetic material that has cooled the raw material gas with the refrigerant.

8. A liquefaction method as described in claim 7, further comprising a step of expanding the raw material gas cooled by the refrigerant to liquefy a portion of the raw material gas, wherein in the step of liquefying the raw material gas by the magnetic body, the raw material gas that has not been liquefied by the expansion is liquefied.

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