System and method for preparing liquid hydrogen through hydrogen self-circulation

Abstract

The invention discloses a system and a method for preparing liquid hydrogen through hydrogen self-circulation, and relates to the technical field of hydrogen liquefaction. The invention provides a system for preparing liquid hydrogen through hydrogen self-circulation. The system comprises a raw material gas pipeline, a refrigerant pipeline, a first condenser set, a second condenser set, a third condenser set, a first expansion compressor set, a second expansion compressor set, a third expansion compressor set, a pre-pressurization compression cooling set, a compression cooler and a high-pressure compression cooling set. High-pressure hydrogen serves as a refrigerant, throttling and condensation of the refrigerant are achieved through circulation of expansion and compression of the high-pressure hydrogen, power can be provided for the compression side through throttling of the expansion side, and the energy consumption problem of the compressor is greatly reduced. Moreover, the cold quantity of the cold source is fully utilized, the throttling condensation effect is achieved through the expansion side of the expansion compressor, the cold source subjected to expansion throttling every time achieves the pre-cooling effect through the trend of the cold source, the utilization efficiency of the cold source is greatly improved, and the operation stability of the device is guaranteed.

Description

Technical Field

[0001] The present invention relates to the technical field of hydrogen liquefaction, and in particular to a system and method for producing liquid hydrogen through self-circulation of hydrogen. Background Art

[0002] The safe and efficient storage and transportation of hydrogen is the key to the hydrogen energy industry. Storing and transporting hydrogen after low-temperature liquefaction will greatly improve the efficiency and safety of hydrogen storage and transportation. However, hydrogen liquefaction is very difficult. During the cooling process, a large amount of conversion heat is released during the conversion of normal and para-hydrogen, further increasing the difficulty of hydrogen refrigeration and liquefaction. Therefore, the energy consumption of hydrogen liquefaction is generally very high. How to reduce the liquefaction energy consumption directly affects the market competitiveness of hydrogen products.

[0003] At the same time, in the process of liquefying hydrogen, how to effectively utilize the cold source and improve the stability of the refrigeration system is also a difficult problem that needs to be solved.

[0004] In view of this, the present invention is proposed. Summary of the invention

[0005] The object of the present invention is to provide a system and method for producing liquid hydrogen by self-circulating hydrogen.

[0006] The present invention is achieved in that:

[0007] In a first aspect, the present invention provides a system for producing liquid hydrogen by self-circulation of hydrogen, which comprises: a raw gas pipeline, a refrigerant pipeline, a first condenser group, a second condenser group, a third condenser group, a first expansion compressor group, a second expansion compressor group, a third expansion compressor group, a pre-boosting compression cooling group, a compression cooler, and a high-pressure compression cooling group;

[0008] The first condenser group is provided with a first flow channel, a second flow channel, a third flow channel and a fourth flow channel, the second condenser group is provided with a first flow channel, a second flow channel and a third flow channel; the third condenser group is provided with a first flow channel and a second flow channel; the first expansion compressor group, the second expansion compressor group and the third expansion compressor group are all provided with an expansion side and a compression side;

[0009] The refrigerant pipeline is simultaneously connected to the second flow channel of the first condenser group and the expansion side of the first expansion compressor group, the second flow channel of the first condenser group is connected to the expansion side of the second expansion compressor group, and the expansion side of the second expansion compressor group is simultaneously connected to the expansion side of the third expansion compressor group and the third flow channel of the second condenser group; the expansion side of the third expansion compressor group is sequentially connected to the second flow channel of the third condenser group, the second flow channel of the second condenser group and the third flow channel of the first condenser group, and the outlet end of the third flow channel of the first condenser group is connected to the pre-boost compression cooling group, the pre-boost compression cooling group is connected to the compression side of the first expansion compressor group, the compression side of the first expansion compressor group is connected to the compression side of the second expansion compressor group, the compression side of the second expansion compressor group is connected to the compression side of the third expansion compressor group, and the compression side of the third expansion compressor group is sequentially connected to the compression cooler and the high-pressure compression cooling group, and the high-pressure compression cooling group is connected to the refrigerant pipeline; the third flow channel of the second condenser group is connected to the expansion side of the first expansion compressor group and the fourth flow channel of the first condenser group, and the outlet of the fourth flow channel of the first condenser group is connected to the compression side of the first expansion compressor group;

[0010] The raw gas pipeline is connected with the first flow passages of the first condenser group, the second condenser group and the third condenser group in sequence to cool the raw gas into liquid hydrogen.

[0011] In an optional embodiment, the number of condensers in the first condenser group and the number of expansion compressors in the first expansion compressor group correspond one to one and are at least two levels; the outlet end of each condenser in the first condenser group is divided into two paths, which are respectively connected to the expansion side of the expansion compressor of the next level in the first expansion compressor group of the next level and the second flow channel of the condenser of the next level in the first condenser group.

[0012] In an optional embodiment, the number of stages of the condenser in the first condenser group and the expansion compressor in the first expansion compressor group are both 5, the number of stages of the second condenser group and the second expansion compressor group corresponds to each other and is 1, and the number of stages of the third condenser group and the third expansion compressor group corresponds to each other and is 1.

[0013] In an optional embodiment, the pre-boost compression and cooling group includes a first pre-boost compressor, a first pre-boost cooler, a second pre-boost compressor and a second pre-boost cooler which are connected in sequence.

[0014] In an optional embodiment, the high-pressure compression and cooling group includes a first high-pressure compressor, a first high-pressure cooler, a second high-pressure compressor, and a second high-pressure cooler connected in sequence.

[0015] In a second aspect, the present invention provides a method for producing liquid hydrogen by self-circulation of hydrogen, which is carried out using a system for producing liquid hydrogen by self-circulation of hydrogen as described in any one of the aforementioned embodiments, and comprises:

[0016] The refrigerant is divided into two streams, one stream is passed into the expansion side of the first expansion compressor group, and the other stream is passed into the second flow channel of the first condenser group for pre-cooling, and is led out from the second flow channel of the first condenser group and passed into the expansion side of the second expansion compressor group, and after cooling and reducing the pressure, it is led out from the expansion side of the second expansion compressor group and divided into two streams, one stream is passed into the third flow channel of the second condenser group, and is mixed with the refrigerant led out from the expansion side of the first expansion compressor group and then passed into the fourth flow channel of the first condenser group, and the other stream is passed into the expansion side of the third expansion compressor group, and after cooling and reducing the pressure, it is led out from the expansion side of the third expansion compressor group and passed into the third condenser group and the first condenser group in sequence. The second flow channel of the second condenser group provides cooling capacity for the first flow channel, the refrigerant drawn from the second flow channel of the second condenser group enters the third flow channel of the first condenser group to provide cooling capacity for the first flow channel and the second flow channel, the refrigerant drawn from the third flow channel of the first condenser group and after being pressurized and cooled by the pre-pressurization compression cooling group is mixed with the refrigerant drawn from the fourth flow channel of the first condenser group and then enters the compression sides of the first expansion compressor group, the second expansion compressor group and the third expansion compressor group in sequence, and the high-pressure hydrogen obtained from the compression side of the third expansion compressor group and after passing through the compression cooler and the high-pressure compression cooling group is used as the refrigerant, completing the self-circulation of the refrigerant;

[0017] The raw gas is sequentially introduced into the first flow channel of the first condenser group, the second condenser group and the third condenser group for precooling, and is drawn out from the first flow channel of the third condenser group and pressure-regulated by a throttle valve to obtain a liquid hydrogen product.

[0018] In an optional embodiment, when the number of condensers in the first condenser group corresponds to the number of expansion compressors in the first expansion compressor group and is at least two levels, the refrigerant is divided into two streams, one stream is passed into the expansion side of the first-level expansion compressor in the first expansion compressor group, and the other stream is passed into the second flow channel of the first-level condenser in the first condenser group. The refrigerant drawn out from the first flow channel of the first-level condenser is also divided into two streams, one stream passes through the expansion side of the intermediate expansion compressor of the first expansion compressor group, and the other stream is passed into the second flow channel of the second-level condenser in the first condenser group. And so on, each time the refrigerant drawn out from the first condenser group is divided into two streams, which are respectively passed into the expansion side of the next-level expansion compressor in the first expansion compressor group and the second flow channel of the next-level condenser in the first condenser group, until the refrigerant is drawn out from the last condenser in the first condenser group and passed into the expansion side of the second expansion compressor group.

[0019] In an optional embodiment, the raw gas is hydrogen.

[0020] In an optional embodiment, the cryogen is hydrogen.

[0021] The present invention has the following beneficial effects:

[0022] The system and method for producing liquid hydrogen by self-circulation of hydrogen provided by the present invention uses high-pressure hydrogen as a refrigerant, and utilizes the expansion and compression of high-pressure hydrogen to circulate to achieve throttling and condensation of the refrigerant itself, wherein the expansion side in the first expansion compressor unit, the second expansion compressor unit, and the third expansion compressor unit can replace the throttling effect, and the throttling of the expansion side can give power to the compression side, greatly reducing the energy consumption problem of the compressor. Moreover, in the process of expanding, compressing, and precooling the high-pressure hydrogen, the temperature of the high-pressure hydrogen can be gradually reached to -251.6°C, which can fully realize the gradual cooling of the raw gas, reduce the amount of refrigerant required for hydrogen liquefaction, and thus reduce energy consumption. The present invention makes full use of the cold capacity of the cold source, realizes the effect of throttling and condensation through the expansion side of the expansion compressor, and the cold source direction enables the cold source after each expansion and throttling to achieve the effect of precooling, greatly improving the utilization efficiency of the cold source and ensuring the stability of the operation of the device. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0024] Figure 1 A schematic diagram of the structure of a system for producing liquid hydrogen by self-circulation of hydrogen provided in an embodiment of the present invention;

[0025] Figure 2 A schematic diagram of a flow path in a system for producing liquid hydrogen by self-circulation of hydrogen provided in an embodiment of the present invention.

[0026] Icon: 100-System for producing liquid hydrogen by self-circulation of hydrogen;

[0027] 111-first condenser group; 1111-first condenser; 1112-second condenser; 1113-third condenser; 1114-fourth condenser; 1115-fifth condenser; 112-second condenser group; 1121-sixth condenser; 113-third condenser group; 1131-seventh condenser; 114-first flow channel; 115-second flow channel; 116-third flow channel; 117-fourth flow channel;

[0028] 121-first expansion compressor group; 1211-first expansion compressor; 1212-second expansion compressor; 1213-third expansion compressor; 1214-fourth expansion compressor; 1215-fifth expansion compressor; 122-second expansion compressor group; 1221-sixth expansion compressor; 123-third expansion compressor group; 1231-seventh expansion compressor; 124-expansion side; 125-compression side;

[0029] 130-pre-boost compression cooling group; 131-first pre-boost compressor; 132-first pre-boost cooler; 133-second pre-boost compressor; 134-second pre-boost cooler;

[0030] 140 - compression cooler;

[0031] 150 - high-pressure compression and cooling group; 151 - first high-pressure compressor; 152 - first high-pressure cooler; 153 - second high-pressure compressor; 154 - second high-pressure cooler. DETAILED DESCRIPTION

[0032] In order to make the purpose, technical scheme and advantages of the embodiments of the present invention clearer, the technical scheme in the embodiments of the present invention will be described clearly and completely below. If the specific conditions are not specified in the embodiments, they are carried out according to conventional conditions or conditions recommended by the manufacturer. If the manufacturer of the reagents or instruments used is not specified, they are all conventional products that can be purchased commercially.

[0033] See also Figure 1 and Figure 2 The present invention provides a system 100 for producing liquid hydrogen by self-circulating hydrogen, which includes: a raw gas pipeline (not shown), a refrigerant pipeline (not shown), a first condenser group 111, a second condenser group 112, a third condenser group 113, a first expansion compressor group 121, a second expansion compressor group 122, a third expansion compressor group 123, a pre-boosting compression cooling group 130, a compression cooler 140, and a high-pressure compression cooling group 150;

[0034] The first condenser group 111 is provided with a first flow channel 114, a second flow channel 115, a third flow channel 116 and a fourth flow channel 117, the second condenser group 112 is provided with a first flow channel 114, a second flow channel 115 and a third flow channel 116; the third condenser group 113 is provided with a first flow channel 114 and a second flow channel 115; the first expansion compressor group 121, the second expansion compressor group 122 and the third expansion compressor group 123 are all provided with an expansion side 124 and a compression side 125;

[0035] The refrigerant pipeline is simultaneously connected to the second flow channel 115 of the first condenser group 111 and the expansion side 124 of the first expansion compressor group 121, the second flow channel 115 of the first condenser group 111 is connected to the expansion side 124 of the second expansion compressor group 122, and the expansion side 124 of the second expansion compressor group 122 is simultaneously connected to the expansion side 124 of the third expansion compressor group 123 and the third flow channel 116 of the second condenser group 112; the expansion side 124 of the third expansion compressor group 123 is sequentially connected to the second flow channel 115 of the third condenser group 113, the second flow channel 115 of the second condenser group 112 and the third flow channel 116 of the first condenser group 111, and the outlet end of the third flow channel 116 of the first condenser group 111 is connected to the pre-boosting compression cooling group 130, and the pre-boosting compression cooling group 130 is communicated with the compression side 125 of the first expansion compressor group 121, the compression side 125 of the first expansion compressor group 121 is communicated with the compression side 125 of the second expansion compressor group 122, the compression side 125 of the second expansion compressor group 122 is communicated with the compression side 125 of the third expansion compressor group 123, the compression side 125 of the third expansion compressor group 123 is communicated with the compression cooler 140 and the high-pressure compression cooling group 150 in sequence, and the high-pressure compression cooling group 150 is communicated with the refrigerant pipeline; the third flow channel 116 of the second condenser group 112 is communicated with the expansion side 124 of the first expansion compressor group 121 and the fourth flow channel 117 of the first condenser group 111, and the outlet of the fourth flow channel 117 of the first condenser group 111 is communicated with the compression side 125 of the first expansion compressor group 121;

[0036] The raw gas pipeline is connected to the first flow passages 114 of the first condenser group 111, the second condenser group 112 and the third condenser group 113 in sequence to cool the raw gas into liquid hydrogen.

[0037] In the present invention, the expansion and compression of the refrigerant are circulated to achieve the throttling and condensation of the refrigerant itself, wherein the expansion side 124 in the first expansion compressor unit 121, the second expansion compressor unit 122 and the third expansion compressor unit 123 can replace the throttling effect, and the throttling of the expansion side 124 can give power to the compression side 125, greatly reducing the energy consumption problem of the compressor. The present invention makes full use of the cold capacity of the cold source, and achieves the effect of throttling and condensation through the expansion side 124 of the expansion compressor. The direction of the cold source enables the cold source after each expansion and throttling to achieve the effect of precooling, which greatly improves the utilization efficiency of the cold source and ensures the stability of the operation of the device.

[0038] In the present invention, the number of condensers in the first condenser group 111, the second condenser group 112, and the third condenser group 113 can be adjusted according to the pre-cooling stage based on the amount of raw hydrogen gas and the temperature and pressure conditions, and the first expansion compressor group 121, the second expansion compressor group 122, and the third expansion compressor group 123 can also be adjusted accordingly.

[0039] Among them, the number of condensers in the first condenser group 111 and the number of expansion compressors in the first expansion compressor group 121 correspond one to one and are at least 2 levels; the number of levels of the second condenser group 112 and the second expansion compressor group 122 correspond and are at least 1 level, and the number of levels of the third condenser group 113 and the third expansion compressor group 123 correspond and are at least 1 level.

[0040] The outlet end of each condenser in the first condenser group 111 is divided into two paths, which are respectively connected to the expansion side 124 of the expansion compressor of the next stage in the first expansion compressor group 121 of the next stage and the second flow channel 115 of the condenser of the next stage in the first condenser group 111. In the present invention, the refrigerant drawn out of the condenser each time is expanded and precooled respectively, so that the temperature of the refrigerant changes gradually in a step-by-step manner, which is conducive to ensuring the stability of the gradual cooling of the raw gas.

[0041] Preferably, the number of stages of the condenser in the first condenser group 111 and the expansion compressor in the first expansion compressor group 121 are both 5, the number of stages of the second condenser group 112 and the second expansion compressor group 122 corresponds to 1, and the number of stages of the third condenser group 113 and the third expansion compressor group 123 corresponds to 1. At this time, the condensers of one to seven stages are respectively a first-stage condenser 1111, a second-stage condenser 1112, a third-stage condenser 1113, a fourth-stage condenser 1114, a fifth-stage condenser 1115, a sixth-stage condenser 1121, and a seventh-stage condenser 1131, wherein the first-stage condenser 1111, the second-stage condenser 1112, the third-stage condenser 1113, the fourth-stage condenser 1114, and the fifth-stage condenser 1115 are used as the first condenser group 111; the sixth-stage condenser 1121 is used as the second condenser group 112; and the seventh-stage condenser 1131 is used as the third condenser group 113.

[0042] Further, the pre-boost compression cooling group 130 includes a first pre-boost compressor 131, a first pre-boost cooler 132, a second pre-boost compressor 133 and a second pre-boost cooler 134 which are connected in sequence. In the present invention, through two-stage compression and cooling, the refrigerant entering the pre-boost compression cooling group 130 can be gradually compressed and cooled so that the refrigerant reaches the required pressure and temperature.

[0043] The high-pressure compression cooling group 150 includes a first high-pressure compressor 151, a first high-pressure cooler 152, a second high-pressure compressor 153, and a second high-pressure cooler 154, which are connected in sequence. In the present invention, through two-stage compression and cooling, the refrigerant entering the pre-boosting compression cooling group 130 can be gradually compressed and cooled so that the refrigerant reaches the required pressure and temperature.

[0044] In addition, the present invention also provides a method for producing liquid hydrogen by self-circulation of hydrogen, which is performed using the above-mentioned system 100 for producing liquid hydrogen by self-circulation of hydrogen, and comprises:

[0045] The refrigerant (normal temperature, 3.5-4.5MpaA high-pressure hydrogen) is divided into two streams, one stream is passed into the expansion side 124 of the first expansion compressor group 121, and the other stream is passed into the second flow channel 115 of the first condenser group 111 for precooling, and is led out from the second flow channel 115 of the first condenser group 111 and passed into the expansion side 124 of the second expansion compressor group 122, and after cooling and reducing the pressure, it is led out from the expansion side 124 of the second expansion compressor group 122 and divided into two streams, one stream is passed into the third flow channel 116 of the second condenser group 112, and is mixed with the refrigerant led out from the expansion side 124 of the first expansion compressor group 121, and then passed into the fourth flow channel 117 of the first condenser group 111, and the other stream is passed into the expansion side 124 of the third expansion compressor group 123, and after cooling and reducing the pressure, it is led out from the expansion side 124 of the third expansion compressor group 123 and passed into the The second flow channel 115 of the third condenser group 113 and the second condenser group 112 provides cooling for the first flow channel 114. The refrigerant drawn from the second flow channel 115 of the second condenser group 112 enters the third flow channel 116 of the first condenser group 111 to provide cooling for the first flow channel 114 and the second flow channel 115. The refrigerant drawn from the third flow channel 116 of the first condenser group 111 and pressurized and cooled by the pre-pressurization compression cooling group 130 is mixed with the refrigerant drawn from the fourth flow channel 117 of the first condenser group 111 and then enters the compression side 125 of the first expansion compressor group 121, the second expansion compressor group 122 and the third expansion compressor group 123 in sequence. The high-pressure hydrogen obtained from the compression side 125 of the third expansion compressor group 123 and after passing through the compression cooler 140 and the high-pressure compression cooling group 150 is used as the refrigerant to complete the self-circulation of the refrigerant.

[0046] The raw gas (hydrogen at room temperature and 2.5-3.5MpaA) is sequentially introduced into the first flow channel 114 of the first condenser group 111, the second condenser group 112 and the third condenser group 113 for pre-cooling, and is drawn out from the first flow channel 114 of the third condenser group 113 and pressure-regulated by a throttle valve to obtain a liquid hydrogen product.

[0047] When the number of condensers in the first condenser group 111 corresponds to the number of expansion compressors in the first expansion compressor group 121 and is at least two stages, the refrigerant is divided into two streams, one stream is passed into the expansion side 124 of the first expansion compressor 1211 in the first expansion compressor group 121, and the other stream is passed into the second flow channel 115 of the first condenser 1111 in the first condenser group 111, and the refrigerant drawn out from the first flow channel 114 of the first condenser 1111 is also divided into two streams, one stream is passed through the middle expansion compressor 121 of the first expansion compressor group 121. The refrigerant is drawn out from the first condenser group 111 each time and is divided into two streams which are respectively passed into the expansion side 124 of the next-stage expansion compressor in the first expansion compressor group 121 and the second flow channel 115 of the next-stage condenser in the first condenser group 111, until the refrigerant is drawn out from the last condenser in the first condenser group 111 and passed into the expansion side 124 of the second expansion compressor group 122.

[0048] The method for producing liquid hydrogen by self-circulation of hydrogen provided by the present invention utilizes high-pressure hydrogen (normal temperature, 4MpaA) as a refrigerant. By expanding, compressing and precooling the high-pressure hydrogen, the temperature of the high-pressure hydrogen can be gradually increased to -251.6°C, which can fully realize the gradual cooling of the raw gas, reduce the amount of refrigerant required for hydrogen liquefaction, and thus reduce energy consumption.

[0049] The features and performance of the present invention are further described in detail below in conjunction with the embodiments.

[0050] Example 1

[0051] In this embodiment, hydrogen (normal temperature, 3MpaA) is used as the raw gas, high-pressure hydrogen (normal temperature, 4MpaA) is used as the initial value of the cold source, and the 7-stage precooling equipment prepares the raw gas into liquid hydrogen for illustration and introduction. In practice, the number of precooling stages can be adjusted according to the gas volume, temperature and pressure of the raw hydrogen.

[0052] The 7-stage pre-cooling equipment in this embodiment are respectively a first-stage condenser 1111, a second-stage condenser 1112, a third-stage condenser 1113, a fourth-stage condenser 1114, a fifth-stage condenser 1115, a sixth-stage condenser 1121, and a seventh-stage condenser 1131, wherein the first-stage condenser 1111, the second-stage condenser 1112, the third-stage condenser 1113, the fourth-stage condenser 1114, and the fifth-stage condenser 1115 serve as the first condenser group 111; the sixth-stage condenser 1121 serves as the second condenser group 112; and the seventh-stage condenser 1131 serves as the third condenser group 113. The first to fifth stage condensers 1115 involved in this embodiment all contain a first flow channel 114, a second flow channel 115, a third flow channel 116, and a fourth flow channel 117; the sixth stage condenser 1121 contains a first flow channel 114, a second flow channel 115, and a third flow channel 116; the seventh stage condenser 1131 contains a first flow channel 114 and a second flow channel 115.

[0053] The number of expansion compressors in the first expansion compressor group 121 corresponds to the number of condensers in the first condenser group 111, the number of the second expansion compressor group 122 corresponds to the second condenser group 112, and the number of the third expansion compressor group 123 corresponds to the third condenser group 113. Therefore, the expansion compressors also have one to seven levels, namely, a first-stage expansion compressor 1211, a second-stage expansion compressor 1212, a third-stage expansion compressor 1213, a fourth-stage expansion compressor 1214, a fifth-stage expansion compressor 1215, a sixth-stage expansion compressor 1221, and a seventh-stage expansion compressor 1231, wherein the first-stage expansion compressor 1211, the second-stage expansion compressor 1212, the third-stage expansion compressor 1213, the fourth-stage expansion compressor 1214, and the fifth-stage expansion compressor 1215 serve as the first expansion compressor group 121; the sixth-stage expansion compressor 1221 serves as the second expansion compressor group 122; and the seventh-stage expansion compressor 1231 serves as the third expansion compressor group 123. The first to seventh stage expansion compressors 1231 all include an expansion side 124 and a compression side 125 .

[0054] The raw gas is pre-cooled through the first flow channel 114 of the first-stage condenser 1111, the second-stage condenser 1112, the third-stage condenser 1113, the fourth-stage condenser 1114, the fifth-stage condenser 1115, the sixth-stage condenser 1121, and the seventh-stage condenser 1131 in sequence, and is finally drawn out from the first flow channel 114 of the seventh-stage condenser 1131 and pressure-regulated by a throttle valve to obtain a liquid hydrogen product.

[0055] High-pressure hydrogen (normal temperature, 4MpaA) is used as a cold source and is first divided into two streams, one stream passes through the expansion side 124 of the first-stage expansion compressor 1211, and the other stream enters the second flow channel 115 of the first-stage condenser 1111 for precooling;

[0056] The high-pressure hydrogen (3.99 MPaA, -63°C) precooled by the primary condenser 1111 is also divided into two streams, one stream passes through the expansion side 124 of the secondary expansion compressor 1212, and the other stream enters the second flow channel 115 of the secondary condenser 1112 for precooling;

[0057] The high-pressure hydrogen (3.98MpaA, -133°C) precooled by the secondary condenser 1112 is also divided into two streams, one stream passes through the expansion side 124 of the third-stage expansion compressor 1213, and the other stream enters the second flow channel 115 of the third-stage condenser 1113 for precooling;

[0058] The high-pressure hydrogen (3.97 MPaA, -178°C) precooled by the third-stage condenser 1113 is also divided into two streams, one stream passes through the expansion side 124 of the fourth-stage expansion compressor 1214, and the other stream enters the second flow channel 115 of the fourth-stage condenser 1114 for precooling;

[0059] The high-pressure hydrogen (3.96MpaA, -206°C) precooled by the fourth-stage condenser 1114 is also divided into two streams, one stream passes through the expansion side 124 of the fifth-stage expansion compressor 1215, and the other stream enters the second flow channel 115 of the fifth-stage condenser 1115 for precooling;

[0060] The high-pressure hydrogen (3.95MpaA, -224°C) precooled by the five-stage condenser 1115 is introduced into the expansion side 124 of the six-stage expansion compressor 1221. After expansion, the pressure is reduced to 0.66MpaA, and the temperature is reduced to -241.5°C. Then, it is divided into two streams. One stream passes through the expansion side 124 of the seven-stage expansion compressor 1231. After expansion, the pressure is reduced to 0.15MpaA, and the temperature is reduced to -251.6°C. It is introduced into the second flow channel 115 of the seven-stage condenser 1131 as a cold source to provide cold energy for the first flow channel 114; the other stream enters the third flow channel 116 of the six-stage condenser 1121 as a cold source to provide cold energy for the first flow channel 114 and the second flow channel 115;

[0061] The low-temperature and low-pressure cold source (0.15MpaA, -251.6°C) after passing through the expansion side 124 of the seven-stage expansion compressor 1231 enters the second flow channel 115 of the seven-stage condenser 1131 and then flows into the second flow channel 115 of the six-stage condenser 1121 as a cold source (0.148MpaA, -241°C) to provide coldness for the first flow channel 114;

[0062] The cold source (0.146MpaA, -227°C) after passing through the second flow channel 115 of the sixth-stage condenser 1121 flows into the third flow channel 116 of the fifth-stage condenser 1115 as a cold source to provide coldness for the first flow channel 114 and the second flow channel 115;

[0063] The cold source (0.144MpaA, -209°C) after passing through the third flow channel 116 of the fifth-stage condenser 1115 flows into the third flow channel 116 of the fourth-stage condenser 1114 as a cold source to provide coldness for the first flow channel 114 and the second flow channel 115;

[0064] The cold source (0.142MpaA, -181°C) after passing through the third flow channel 116 of the fourth-stage condenser 1114 flows into the third flow channel 116 of the third-stage condenser 1113 as a cold source to provide coldness for the first flow channel 114 and the second flow channel 115;

[0065] The cold source (0.139MpaA, -136°C) after passing through the third flow channel 116 of the third-stage condenser 1113 flows into the third flow channel 116 of the secondary condenser 1112 as a cold source to provide cold energy for the first flow channel 114 and the second flow channel 115;

[0066] The cold source (0.136MpaA, -66°C) after passing through the third flow channel 116 of the secondary condenser 1112 flows into the third flow channel 116 of the primary condenser 1111 as a cold source to provide coldness for the first flow channel 114 and the second flow channel 115;

[0067] After the third flow channel 116 of the primary condenser 1111 provides cooling capacity for the primary condenser 1111, the pressure drops to 0.132MpaA, and the temperature rises to 37°C. At this time, the hydrogen at room temperature and low pressure is passed into the first pre-boosting compressor 131 for pressurization and the first pre-boosting cooler 132 for cooling to obtain hydrogen at room temperature of 0.28MpaA. Then, the hydrogen at room temperature of 0.6MpaA is obtained after the second pre-boosting compressor 133 is pressurized and the second pre-boosting cooler 134 is cooled.

[0068] The cold source (0.66MpaA, -241.5°C) entering the third flow channel 116 of the sixth-stage condenser 1121 passes through the sixth-stage condenser 1121 (0.65MpaA, -227°C) and is mixed with the cold source (0.65MpaA, -226.3°C) expanded by the expansion side 124 of the five-stage expansion compressor 1215 (0.65MpaA, -226.5°C) and then passes into the fourth flow channel 117 of the five-stage condenser 1115 as a cold source to provide coldness for the first flow channel 114 and the second flow channel 115;

[0069] After passing through the fifth-stage condenser 1115 (0.64MpaA, -209℃) and the cold source (0.64MpaA, -208.6℃) expanded by the expansion side 124 of the four-stage expansion compressor 1214, the mixed (0.64MpaA, -208.9℃) enters the fourth flow channel 117 of the four-stage condenser 1114 as a cold source to provide cooling for the first flow channel 114 and the second flow channel 115.

[0070] After passing through the fourth-stage condenser 1114 (0.63MpaA, -181°C) and the cold source (0.63MpaA, -181.5°C) expanded through the expansion side 124 of the third-stage expansion compressor 1213, the mixed (0.63MpaA, -181.1°C) enters the fourth flow channel 117 of the third-stage condenser 1113 as a cold source to provide cooling for the first flow channel 114 and the second flow channel 115.

[0071] After passing through the tertiary condenser 1113 (0.62MpaA, -136°C) and the cold source (0.62MpaA, -136.3°C) expanded through the expansion side 124 of the secondary expansion compressor 1212, the mixed (0.62MpaA, -136.1°C) enters the fourth flow channel 117 of the secondary condenser 1112 as a cold source to provide cooling for the first flow channel 114 and the second flow channel 115.

[0072] After passing through the secondary condenser 1112 (0.61MpaA, -66℃) and the cold source (0.61MpaA, -65.9℃) expanded through the expansion side 124 of the first expansion compressor 1211, it is mixed (0.61MpaA, -66℃) and enters the fourth flow channel 117 of the first condenser 1111 as a cold source to provide cooling for the first flow channel 114 and the second flow channel 115.

[0073] After passing through the primary condenser 1111 (0.6MpaA, 37°C) and mixing with the above hydrogen A (0.6MpaA, 37.5°C), it is introduced into the compression side 125 of the primary expansion compressor 1211 for compression;

[0074] After being compressed by the compression side 125 of the first expansion compressor 1211 (0.67MpaA, 50.7°C), it is passed into the compression side 125 of the second expansion compressor 1212 for compression;

[0075] After being compressed by the compression side 125 of the secondary expansion compressor 1212 (0.72MpaA, 59.7°C), it is passed into the compression side 125 of the tertiary expansion compressor 1213 for compression;

[0076] After being compressed by the compression side 125 of the third-stage expansion compressor 1213 (0.756MpaA, 65.9°C), it is passed into the compression side 125 of the fourth-stage expansion compressor 1214 for compression;

[0077] After being compressed by the compression side 125 of the four-stage expansion compressor 1214 (0.782MpaA, 70.4°C), it is passed into the compression side 125 of the five-stage expansion compressor 1215 for compression;

[0078] After being compressed by the compression side 125 of the five-stage expansion compressor 1215 (0.803MpaA, 73.9°C), it is passed into the compression side 125 of the six-stage expansion compressor 1221 for compression;

[0079] After being compressed by the compression side 125 of the six-stage expansion compressor 1221 (0.817MpaA, 76°C), it is passed into the compression side 125 of the seven-stage expansion compressor 1231 for compression;

[0080] After being compressed by the compression side 125 of the seven-stage expansion compressor 1231 (0.824MpaA, 77.2°C), it is passed into the compression cooler 140 for cooling;

[0081] After being cooled to room temperature by the compression cooler 140, it is passed into the first high-pressure compressor 151 for pressurization and cooled by the first high-pressure cooler 152 to obtain hydrogen at room temperature of 1.8MpaA. It is then pressurized by the second high-pressure compressor 153 and cooled by the second high-pressure cooler 154 to obtain hydrogen at room temperature of 4MpaA. This high-pressure hydrogen (room temperature, 4MpaA) is used as the above-mentioned cold source to start, thus completing the refrigerant circulation process.

[0082] The system 100 and method for producing liquid hydrogen by self-circulation of hydrogen provided by the present invention use high-pressure hydrogen as a refrigerant, and use the expansion and compression of high-pressure hydrogen to circulate to achieve throttling and condensation of the refrigerant itself, wherein the expansion side 124 in the first expansion compressor unit 121, the second expansion compressor unit 122 and the third expansion compressor unit 123 can replace the throttling effect, and the throttling of the expansion side 124 can give power to the compression side 125, which greatly reduces the energy consumption of the compressor. In addition, in the process of expanding, compressing and precooling the high-pressure hydrogen, the temperature of the high-pressure hydrogen can be gradually reached to -251.6°C, which can fully realize the gradual cooling of the raw gas, reduce the amount of refrigerant required for hydrogen liquefaction, and thus reduce energy consumption. The present invention makes full use of the cold capacity of the cold source, and realizes the effect of throttling and condensation through the expansion side 124 of the expansion compressor. The cold source direction enables the cold source after each expansion and throttling to achieve the effect of precooling, which greatly improves the utilization efficiency of the cold source and ensures the stability of the operation of the device.

[0083] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A system for producing liquid hydrogen by self-circulation of hydrogen, characterized in that: It includes: Raw gas pipeline, refrigerant pipeline, first condenser group, second condenser group, third condenser group, first expansion compressor group, second expansion compressor group, third expansion compressor group, pre-boosting compression cooling group, compression cooler, high-pressure compression cooling group; The first condenser group is provided with a first flow channel, a second flow channel, a third flow channel and a fourth flow channel, the second condenser group is provided with a first flow channel, a second flow channel and a third flow channel; the third condenser group is provided with a first flow channel and a second flow channel; the first expansion compressor group, the second expansion compressor group and the third expansion compressor group are all provided with an expansion side and a compression side; The refrigerant pipeline is simultaneously connected to the second flow channel of the first condenser group and the expansion side of the first expansion compressor group, the second flow channel of the first condenser group is connected to the expansion side of the second expansion compressor group, and the expansion side of the second expansion compressor group is simultaneously connected to the expansion side of the third expansion compressor group and the third flow channel of the second condenser group; the expansion side of the third expansion compressor group is sequentially connected to the second flow channel of the third condenser group, the second flow channel of the second condenser group and the third flow channel of the first condenser group, and the outlet end of the third flow channel of the first condenser group is connected to the pre-boost compression cooling group, the pre-boost compression cooling group is connected to the compression side of the first expansion compressor group, the compression side of the first expansion compressor group is connected to the compression side of the second expansion compressor group, the compression side of the second expansion compressor group is connected to the compression side of the third expansion compressor group, and the compression side of the third expansion compressor group is sequentially connected to the compression cooler and the high-pressure compression cooling group, and the high-pressure compression cooling group is connected to the refrigerant pipeline; the third flow channel of the second condenser group is connected to the expansion side of the first expansion compressor group and the fourth flow channel of the first condenser group, and the outlet of the fourth flow channel of the first condenser group is connected to the compression side of the first expansion compressor group; The raw gas pipeline is connected with the first flow passages of the first condenser group, the second condenser group and the third condenser group in sequence to cool the raw gas into liquid hydrogen.

2. The system for producing liquid hydrogen by self-circulation of hydrogen according to claim 1, characterized in that: The number of condensers in the first condenser group and the number of expansion compressors in the first expansion compressor group correspond one to one and are at least two levels; the outlet end of each condenser in the first condenser group is divided into two paths, which are respectively connected to the expansion side of the expansion compressor of the next level in the first expansion compressor group of the next level and the second flow channel of the condenser of the next level in the first condenser group.

3. The system for producing liquid hydrogen by self-circulation of hydrogen according to claim 1, characterized in that: The number of stages of the condenser in the first condenser group and the expansion compressor in the first expansion compressor group are both 5, the number of stages of the second condenser group and the second expansion compressor group corresponds to 1, and the number of stages of the third condenser group and the third expansion compressor group corresponds to 1.

4. The system for producing liquid hydrogen by self-circulation of hydrogen according to claim 1, characterized in that: The pre-boost compression and cooling group includes a first pre-boost compressor, a first pre-boost cooler, a second pre-boost compressor and a second pre-boost cooler which are connected in sequence.

5. The system for producing liquid hydrogen by hydrogen self-circulation according to claim 1, characterized in that: The high-pressure compression and cooling group includes a first high-pressure compressor, a first high-pressure cooler, a second high-pressure compressor, and a second high-pressure cooler which are connected in sequence.

6. A method for producing liquid hydrogen by self-circulation of hydrogen, characterized in that: The method is carried out using a system for producing liquid hydrogen by self-circulation of hydrogen as claimed in any one of claims 1 to 5, comprising: The refrigerant is divided into two streams, one stream is passed into the expansion side of the first expansion compressor group, and the other stream is passed into the second flow channel of the first condenser group for pre-cooling, and is led out from the second flow channel of the first condenser group and passed into the expansion side of the second expansion compressor group, and after cooling and reducing the pressure, it is led out from the expansion side of the second expansion compressor group and divided into two streams, one stream is passed into the third flow channel of the second condenser group, and is mixed with the refrigerant led out from the expansion side of the first expansion compressor group and then passed into the fourth flow channel of the first condenser group, and the other stream is passed into the expansion side of the third expansion compressor group, and after cooling and reducing the pressure, it is led out from the expansion side of the third expansion compressor group and passed into the third condenser group and the first condenser group in sequence. The second flow channel of the second condenser group provides cooling capacity for the first flow channel, the refrigerant drawn from the second flow channel of the second condenser group enters the third flow channel of the first condenser group to provide cooling capacity for the first flow channel and the second flow channel, the refrigerant drawn from the third flow channel of the first condenser group and after being pressurized and cooled by the pre-pressurization compression cooling group is mixed with the refrigerant drawn from the fourth flow channel of the first condenser group and then enters the compression sides of the first expansion compressor group, the second expansion compressor group and the third expansion compressor group in sequence, and the high-pressure hydrogen obtained from the compression side of the third expansion compressor group and after passing through the compression cooler and the high-pressure compression cooling group is used as the refrigerant, completing the self-circulation of the refrigerant; The raw gas is sequentially introduced into the first flow channel of the first condenser group, the second condenser group and the third condenser group for precooling, and is drawn out from the first flow channel of the third condenser group and pressure-regulated by a throttle valve to obtain a liquid hydrogen product.

7. The method for producing liquid hydrogen by hydrogen self-circulation according to claim 6, characterized in that: When the number of condensers in the first condenser group corresponds to the number of expansion compressors in the first expansion compressor group and is at least 2 levels, the refrigerant is divided into two streams, one stream is passed into the expansion side of the first-level expansion compressor in the first expansion compressor group, and the other stream is passed into the second flow channel of the first-level condenser in the first condenser group. The refrigerant drawn out from the first flow channel of the first-level condenser is also divided into two streams, one stream passes through the expansion side of the intermediate expansion compressor of the first expansion compressor group, and the other stream is passed into the second flow channel of the second-level condenser in the first condenser group. And so on. Each time the refrigerant drawn out from the first condenser group is divided into two streams, which are respectively passed into the expansion side of the next-level expansion compressor in the first expansion compressor group and the second flow channel of the next-level condenser in the first condenser group, until the refrigerant is drawn out from the last condenser in the first condenser group and passed into the expansion side of the second expansion compressor group.

8. The method for producing liquid hydrogen by hydrogen self-circulation according to claim 6, characterized in that: The raw material gas is hydrogen.

9. The method for producing liquid hydrogen by hydrogen self-circulation according to claim 6, characterized in that: The refrigerant is hydrogen.

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