MIXED REFRIGERANT HYDROGEN LIQUEFACTION DEVICE AND ITS METHOD OF USE

Abstract

The present invention relates to a mixed-refrigerant hydrogen liquefaction device for achieving energy consumption reduction. The process comprises a normal-pressure precooling cold box II, a vacuum cryogenic cold box III, a hydrogen refrigeration cycle compressor unit, a nitrogen cycle refrigeration unit, and a mixed-refrigerant cycle refrigeration unit. The precooling section uses a mixed-refrigerant process and a nitrogen cycle refrigeration process as the primary cooling energy sources. The refrigerant cycle is the primary cooling energy source in the temperature range of 303 K to 113 K. The liquid nitrogen cycle is the primary cooling energy source in the temperature range of 130 K to 80 K.The hydrogen refrigeration cycle provides cold energy for a temperature range from 80 K to 20 K. Most of the generated gas in a storage section is recovered by an ejector. A plate finned heat exchanger is filled with orthohydrogen-to-parahydrogen conversion catalysts to achieve a parahydrogen content of ≥98% in the liquefied hydrogen. The hydrogen liquefaction process exhibits low energy consumption, and the precooling cold box and the cryogenic cold box utilize different design schemes, resulting in reduced device and manufacturing costs. [Fig. 1]

Description

Title of the invention: MIXED REFRIGERANT HYDROGEN LIQUEFACTION DEVICE AND METHOD OF USING SAME Technical field

[0001] The present invention relates to the field of low temperature gas liquefaction, in particular to a mixed refrigerant hydrogen liquefaction device and a method of using the same. Prior art

[0002] As an important clean energy, liquid hydrogen is mainly needed in the aerospace and new energy automobile sectors. The use of liquid hydrogen in aerospace is becoming more and more mature, and its demand growth is relatively stable. As the main means of large-scale hydrogen transportation, liquid hydrogen is becoming increasingly important. The high energy consumption of liquid hydrogen production limits the development of liquid hydrogen. The energy consumption of the existing hydrogen liquefaction device is 4.86 kW / kgLH2 in the precooling section, 8.65 kW / kgLH2 in the cryogenic section, and 13.5 kW / kgLH2 overall. It is imperative to reduce the energy consumption of the hydrogen liquefaction process by optimizing the process. Summary of the invention

[0003] The present invention aims to provide a mixed refrigerant hydrogen liquefaction device, which significantly reduces the energy consumption in the hydrogen liquefaction process. According to the present invention, the energy consumption of the precooling section can be reduced to 3.2 kW / kgLH2 and the energy consumption of the cryogenic section can be reduced to 6.78 kW / kgLH2 and the overall energy consumption is 10 kW / kgLH2, which are significantly lower than those of the conventional hydrogen liquefaction device.

[0004] In order to achieve the above objective, the present invention may use the following technical scheme: a mixed refrigerant hydrogen liquefaction device, wherein the device comprises a refrigerant compression unit, a pre-cooling cold box and a cryogenic cold box which are connected to each other by means of pipelines, wherein the refrigerant compression unit is provided with a dehydration molecular sieve adsorber, a hydrogen compressor unit, a nitrogen compressor unit and a mixed refrigerant refrigeration unit, the pre-cooling cold box is provided with a primary precooling heat exchanger, a secondary precooling heat exchanger and a low temperature molecular sieve adsorber and the cryogenic cold box is provided with a cryogenic heat exchanger, an ejector, a supercooling heat exchanger, a gas-liquid separator, a primary hydrogen expander and a secondary hydrogen expander.

[0005] Preferably, the dehydration molecular sieve adsorber in the refrigerant compression unit is connected to a raw material hydrogen channel of the primary precooling heat exchanger and the secondary precooling heat exchanger and the low-temperature molecular sieve adsorber in the precooling cold box by means of a second pipeline, a third pipeline and a fourth pipeline, and then is connected to a raw material hydrogen channel of the cryogenic heat exchanger, the ejector and a raw material hydrogen channel of the supercooling heat exchanger in the cryogenic cold box, in sequence, by means of a fifth pipeline, a sixth pipeline and a seventh pipeline to form a circulation channel in the entire process from raw hydrogen to liquid hydrogen.

[0006] Preferably, the outlet of the hydrogen compressor unit in the refrigerant compression unit is connected to the supercharging ends of the primary hydrogen expander and the secondary hydrogen expander and to the high-pressure circulating hydrogen channels of the primary precooling heat exchanger and the secondary precooling heat exchanger in the precooling cold box in sequence by means of an eleventh pipeline, a twelfth pipeline and a thirteenth pipeline, and then is connected to a high-pressure circulating hydrogen channel of the cryogenic heat exchanger in the cryogenic cold box by means of a fourteenth pipeline and is connected to the primary hydrogen expander, the secondary hydrogen expander and a throttle valve by means of a fifth pipeline, a seventeenth pipeline and a nineteenth pipeline among three bypass pipelines,respectively, the throttle valve is connected to the low-temperature circulating hydrogen channels of the gas-liquid separator and the supercooling heat exchanger in sequence by means of a twentieth pipeline, a twenty-first pipeline and a twenty-second pipeline, the gas-liquid separator is connected to a first low-pressure circulating hydrogen channel of the cryogenic heat exchanger, the first low-pressure circulating hydrogen channels of the secondary precooling heat exchanger and the primary precooling heat exchanger and a low-pressure section of the compressor unit, of hydrogen in sequence by means of a twenty-third pipeline, a twenty-fourth pipeline, a twenty-fifth pipeline and a twenty-sixth pipeline, the primary hydrogen expander and the secondary hydrogen expander are connected to a second low-pressure circulating hydrogen channel of the cryogenic heat exchanger by means of a sixteenth pipeline and an eighteenth pipeline, respectively, and then is connected to the second low-pressure circulating hydrogen channels of the secondary pre-cooling heat exchanger and the primary pre-cooling heat exchanger and to a high-pressure section of the hydrogen compressor unit by means of a twenty-seventh pipeline, a twenty-eighth pipeline and a twenty-ninth pipeline, to form a hydrogen refrigeration circulation channel.

[0007] Preferably, the outlet of the nitrogen compressor unit is connected to a high-pressure nitrogen channel of the primary pre-cooling heat exchanger and a throttle valve in the pre-cooling cold box in sequence by means of a thirtieth pipeline and a thirty-first pipeline, and then is connected to the inlets of the secondary pre-cooling heat exchanger, the primary pre-cooling heat exchanger and the nitrogen compressor unit by means of a thirty-second pipeline,of a thirty-third pipeline and a thirty-fourth pipeline in sequence to form a nitrogen refrigeration circulation channel and the outlet of the mixed refrigerant compressor unit is connected to a high-pressure refrigerant channel of the primary pre-cooling heat exchanger and a throttle valve in the pre-cooling cold box by means of a thirty-fifth pipeline and a thirty-sixth pipeline in sequence, and then is connected to the inlets of the primary pre-cooling heat exchanger and the mixed refrigerant compressor unit by means of a thirty-seventh pipeline and a thirty-eighth pipeline in sequence to form a mixed refrigerant refrigeration circulation channel. ,

[0008] Preferably, the primary precooling heat exchanger, the secondary precooling heat exchanger, the cryogenic heat exchanger and the supercooling heat exchanger are all high-efficiency plate fin heat exchangers, the primary hydrogen expander and the secondary hydrogen expander are both centrifugal expanders braked by a supercharger, the low-pressure section of the hydrogen compressor unit is a reciprocating compressor, the high-pressure section of the hydrogen compressor unit is a centrifugal compressor, and the nitrogen compressor unit and the mixed refrigerant compressor unit are centrifugal compressors.

[0009] A method of using the mixed refrigerant hydrogen liquefaction device comprises the following steps:

[0010] 1) the raw hydrogen is put into communication with an inlet pipe of the dehydration molecular sieve adsorber, removes water at 0.1 ppm, then enters the primary precooling heat exchanger in the precooling cold box by means of the second pipeline to be cooled to 113°K, then enters the secondary precooling heat exchanger filled with orthohydrogen-parahydrogen conversion catalysts by means of the third pipeline for orthohydrogen-parahydrogen conversion to be cooled to 80°K; then enters the low-temperature molecular sieve adsorber by means of the fourth pipeline to remove traces of oxygen, nitrogen, argon and methane, the material flow from the low-temperature adsorber communicates with the fifth pipeline of the cryogenic cold box and enters the cryogenic heat exchanger filled with orthohydrogen and parahydrogen conversion catalysts to be cooled to 25°K,the material flow from HX3 is communicated with the ejector by means of the sixth pipeline to reduce the pressure to 0.57 MPa, at the same time, the bog gas is introduced and enters the supercooling heat exchanger filled with the orthohydrogen and parahydrogen conversion catalysts by means of the seventh pipeline to be cooled to 22°K, then the throttle valve transfers the liquid hydrogen to a storage system and the bog in the storage system is reliquefied by means of the ejector; ,

[0011] 2) the output of the hydrogen compressor unit is connected with the supercharging ends of the primary hydrogen expander and the secondary hydrogen expander by means of the eleventh pipeline in sequence and the high-pressure hydrogen is supercharged in sequence, then passes by means of the twelfth pipeline and the thirteenth pipeline in sequence and is cooled to 80°K in the pre-cooling cold box;the high-pressure hydrogen is communicated with the cryogenic heat exchanger in the cryogenic cold box by means of the fourteenth pipeline, after the high-pressure hydrogen has been cooled to 70°K, a separate stream enters the primary hydrogen expander by means of the fifteenth pipeline to be cooled to 44.3°K, and then returns to the cryogenic heat exchanger by means of the sixteenth pipeline, after another separate stream has been cooled to 50°K, another separate stream enters the secondary hydrogen expander by means of the seventeenth pipeline to be cooled to 28.8°K, returns to the cryogenic heat exchanger by means of the eighteenth pipeline, and then is combined with the stream at the outlet of the primary hydrogen expander after being reheated and passes through the heat exchanger; cryogenic heat, and then is communicated with the pre-cooling heat exchanger and the pre-cooling heat exchanger by means of a twenty-seventh pipeline and a twenty-eighth pipeline in sequence, the hydrogen medium returns to the inlet of the high-pressure section of the hydrogen compression unit by means of a twenty-ninth pipeline after being reheated; the remaining stream is further cooled to 25°K and is connected to the throttle valve by means of the nineteenth pipeline and is communicated with the gas-liquid separator by means of the twentieth pipeline after the throttle valve has been cooled to 20°K;after the gas-liquid separation, the liquid phase is communicated with the supercooling heat exchanger by means of the twenty-first pipeline, the liquid hydrogen returns to the gas-liquid separator by means of the twenty-second pipeline after being partially evaporated in the supercooling heat exchanger to form a thermosiphon loop;the gas phase of the gas-liquid separator is communicated with the cryogenic heat exchanger, the secondary pre-cooling heat exchanger and the primary pre-cooling heat exchanger by means of the twenty-third pipeline, the twenty-fourth pipeline and the twenty-fifth pipeline in sequence and then enters the low-pressure section of the hydrogen compressor unit by means of the twenty-sixth pipeline after being warmed up to the normal temperature, and then is combined with the medium-pressure hydrogen in the high-pressure section of the hydrogen compression unit after being supercharged by means of the low-pressure section of the hydrogen compression unit, so as to form a set of hydrogen refrigeration cycle; ;

[0012] 3) Nitrogen at the outlet of the nitrogen compressor unit enters the cold box precooling by means of a thirtieth pipeline, is cooled to 113°K by means of the primary precooling heat exchanger, is communicated with the throttle valve by means of the thirty-first pipeline and is communicated with the secondary precooling heat exchanger and the primary precooling heat exchanger by means of a thirty-second pipeline and a thirty-third pipeline in sequence after the throttle valve is cooled to 80°K, and then returns to the inlet of the nitrogen compressor unit by means of a thirty-fourth pipeline, so as to form a set of nitrogen refrigeration cycle and provide cold energy for the temperature range of 113°K to 80°K.

[0013] 4) the mixed refrigerant at the outlet of the mixed refrigerant compressor unit enters the pre-cooling cold box and the primary pre-cooling heat exchanger by means of a thirty-fifth pipe for be cooled to 113°K and is communicated with the throttling valve by means of the thirty-sixth pipeline, returns to the primary pre-cooling heat exchanger by means of a thirty-seventh pipeline after cooling from the throttling valve, leaves the pre-cooling cold box by means of a thirty-eighth pipeline and returns to the inlet of the mixed refrigerant compressor unit, so as to form a set of refrigeration cycles of the mixed refrigerant and provide cooling energy for the temperature range of 303°K to 113°K.

[0014] Preferably, the proportions of orthohydrogen and parahydrogen in step 1) are 2.2% and 97.8% respectively and the proportions of orthohydrogen and parahydrogen in the storage system are 1% and 99% respectively.

[0015] Preferably, the medium of the nitrogen refrigeration cycle of step 3) is pure nitrogen.

[0016] Preferably, the mixed refrigerant of step 4) consists of methane, ethylene, propane, isopentane and nitrogen.

[0017] The present invention has the positive effect that the above scheme reduces the losses of the purification, conversion and liquefaction processes as much as possible by means of the continuous conversion and heat exchange of the orthohydrogen-parahydrogen conversion catalysts in the secondary precooling heat exchanger, the cryogenic heat exchanger and the supercooling heat exchanger, the removal of impurities by low-temperature adsorption and the recovery of the bog by the ejector, thereby reducing the energy consumption. The energy consumption of the cryogenic section is reduced to 6.78 kW / kgLH2 by means of two sets of two-stage expander refrigeration and liquid hydrogen throttle refrigeration. The energy consumption of the precooling section is reduced to 3.2 kW / kgLH2 by using nitrogen cycle refrigeration and mixed refrigerant cycle refrigeration.The overall energy consumption of the hydrogen liquefaction process is 10 kW / kgLH2, which is significantly lower than that of the conventional hydrogen liquefaction process. Brief description of the drawings.

[0018] [Fig-1] is a schematic structural diagram of the present invention. Description of the embodiments

[0019] The present invention will be described in detail with reference to the drawings attached hereinafter. As shown in [Fig.l], the hydrogen liquefaction device according to the present invention comprises a refrigerant compression unit I, a pre-cooling cold box II and a cryogenic cold box III which are connected to each other by means of pipelines, wherein the refrigerant compression unit I is equipped with a dehydration molecular sieve adsorber SI, a hydrogen compressor unit Cl, a nitrogen compressor unit C2 and a mixed refrigerant refrigeration unit C3. The precooling cold box II is equipped with a primary precooling heat exchanger HX1, a secondary precooling heat exchanger HX2 and a low-temperature molecular sieve adsorber S2. The cryogenic cold box III is equipped with a cryogenic heat exchanger HX3, an ejector El, a supercooling heat exchanger HX4, a gas-liquid separator D2,a primary hydrogen expander XI and a secondary hydrogen expander X2. The dehydration molecular sieve adsorber SI in the refrigerant compression unit I is connected to a raw material hydrogen channel of the primary precooling heat exchanger HX1 and the secondary precooling heat exchanger HX2 and the low-temperature molecular sieve adsorber S2 in the precooling cold box II by means of a second pipeline 2, a third pipeline 3 and a fourth pipeline 4, and then is connected to a raw material hydrogen channel of the cryogenic heat exchanger HX3, the ejector El and a raw material hydrogen channel of the supercooling heat exchanger HX4 in the cryogenic cold box III, in sequence, by means of a fifth pipeline 5,of a sixth pipe 6 and a seventh pipe 7 to form a circulation channel in the entire process from raw hydrogen to liquid hydrogen. The outlet of the hydrogen compressor unit C1 in the refrigerant compression unit I is connected to the supercharging ends of the primary hydrogen expander XI and the secondary hydrogen expander X2 and to the high-pressure circulating hydrogen channels of the primary precooling heat exchanger HX1 and the secondary precooling heat exchanger HX2 in the precooling cold box II in sequence by means of an eleventh pipeline 11, a twelfth pipeline 12 and a thirteenth pipeline 13, and then is connected to a high-pressure circulating hydrogen channel of the cryogenic heat exchanger HX3 in the cryogenic cold box III by means of a fourteenth pipeline 14 and is connected to the primary hydrogen expander XI,to the secondary hydrogen expander X2 and a throttle valve VI by means of a fifteenth pipe 15, a seventeenth pipe 17 and a nineteenth pipe 19 among three bypass pipes, respectively. The throttle valve V1 is connected to the low-temperature circulating hydrogen channels of the gas-liquid separator D2 and the supercooling heat exchanger HX4 in sequence by means of a twentieth pipe 20, a twenty-first pipe 21 and a twenty-second pipe 22. The gas-liquid separator D2 is connected to a first, low-pressure circulating hydrogen channel of the cryogenic heat exchanger HX3, to the first low-pressure circulating hydrogen channels of the secondary pre-cooling heat exchanger HX2 and the primary pre-cooling heat exchanger HX1 and to a low-pressure section of the hydrogen compressor unit Cl, in sequence by means of a twenty-third pipe 23, a twenty-fourth pipe 24, a twenty-fifth pipe 25 and a twenty-sixth pipe 26.The primary hydrogen expander XI and the secondary hydrogen expander X2 are connected to a second low-pressure circulating hydrogen channel of the cryogenic heat exchanger HX3 by means of a sixteenth pipe 16 and an eighteenth pipe 18 respectively, and then are connected to the second low-pressure circulating hydrogen channels of the secondary pre-cooling heat exchanger HX2 and the primary pre-cooling heat exchanger HX1 and to a high-pressure section of the hydrogen compressor unit C1 by means of a twenty-seventh pipe 27, a twenty-eighth pipe 28 and a twenty-ninth pipe 29, so as to form a hydrogen refrigeration circulating channel.The outlet of the nitrogen compressor unit C2 is connected to a high-pressure nitrogen channel of the primary precooling heat exchanger HX1 and a throttle valve V2 in the precooling cold box II in sequence by means of a thirtieth pipeline 30 and a thirty-first pipeline 31, and then is connected to the inlets of the secondary precooling heat exchanger HX2, the primary precooling heat exchanger HX1 and the nitrogen compressor unit C2 by means of a thirty-second pipeline 32, a thirty-third pipeline 33 and a thirty-fourth pipeline 34 in sequence to form a nitrogen refrigeration circulation channel.The outlet of the mixed refrigerant compressor unit C3 is connected to a high-pressure refrigerant channel of the primary precooling heat exchanger HX1 and a throttle valve V3 in the precooling cold box II by means of a thirty-fifth pipe 35 and a thirty-sixth pipe 36 in sequence, and then is connected to the inlets of the primary precooling heat exchanger HX1 and the mixed refrigerant compressor unit C3 by means of a thirty-seventh pipe 37 and a thirty-eighth pipe 38 in sequence to form a refrigeration circulation channel of the mixed refrigerant. The HX1 primary precooling heat exchanger, HX2 secondary precooling heat exchanger, HX3 cryogenic heat exchanger and HX4 supercooling heat exchanger are all high efficiency plate fin heat exchangers.Both the primary hydrogen expander XI and the secondary hydrogen expander X2 are compressor-braked centrifugal expanders. supercharging. The low-pressure section of the C1 hydrogen compressor unit is a reciprocating compressor. The high-pressure section of the C1 hydrogen compressor unit is a centrifugal compressor. The C2 nitrogen compressor unit and the C3 mixed refrigerant compressor unit are centrifugal compressors.

[0020] A method of using the mixed refrigerant hydrogen liquefaction device comprises the following steps:

[0021] 1) The raw hydrogen is connected to an inlet pipe 1 of the dehydration molecular sieve adsorber SI, removes water at 0.1 ppm, then enters the primary precooling heat exchanger HX1 in the precooling cold box II by means of the second pipeline 2 to be cooled to 113°K, then enters the secondary precooling heat exchanger HX2 filled by orthohydrogen-parahydrogen conversion catalysts by means of the third pipeline 3 for orthohydrogen-parahydrogen conversion to be cooled to 80°K; then enters the low-temperature molecular sieve adsorber S2 by means of the fourth pipeline 4 to remove traces of oxygen, nitrogen, argon and methane,the material flow from the low-temperature adsorber communicates with the fifth pipeline 5 of the cryogenic cold box III and enters the cryogenic heat exchanger HX3 filled with orthohydrogen and parahydrogen conversion catalysts to be cooled to 25°K, the proportions of orthohydrogen and parahydrogen are 2.2% and 97.8% respectively, the material flow from HX3 is communicated with the ejector El by means of the sixth pipeline 6 to reduce the pressure to 0.57 MPa, at the same time, the bog gas is introduced and enters the supercooling heat exchanger HX4 filled with the orthohydrogen and parahydrogen conversion catalysts by means of the seventh pipeline 7 to be cooled to 22°K,then the throttle valve transfers the liquid hydrogen to a storage system and the bog in the storage system is reliquefied by means of the ejector El and the proportions of orthohydrogen and parahydrogen in the storage system are 1% and 99% respectively.

[0022] 2) The outlet of the hydrogen compressor unit Cl is connected, with the supercharging ends of the primary hydrogen expander X1 and the secondary hydrogen expander X2 by means of the eleventh pipeline 11 in sequence and the high-pressure hydrogen is supercharged in sequence, then passes by means of the twelfth pipeline 12 and the thirteenth pipeline 13 in sequence and is cooled to 80°K in the pre-cooling cold box II; the high-pressure hydrogen is communicated with the cryogenic heat exchanger HX3 in the cryogenic cold box III by means of the fourteenth pipeline 14, after the high-pressure hydrogen is cooled to 70°K, a separate flow enters the primary hydrogen expander XI by means of the fifteenth pipe 15 to be cooled to 44.3°K, then returns to the cryogenic heat exchanger HX3 by means of the sixteenth pipe 16, after another separate stream has been cooled to 50°K, another separate stream enters the secondary hydrogen expander X2 by means of the seventeenth pipe 17 to be cooled to 28.8°K, returns to the cryogenic heat exchanger HX3 by means of the eighteenth pipe 18, then is combined with the stream at the outlet of the primary hydrogen expander XI after being reheated and passes through the cryogenic heat exchanger HX3, then is communicated with the precooling heat exchanger HX2 and the precooling heat exchanger HX1 by means of a twenty-seventh pipe 27 and of a twenty-eighth pipeline 28 in sequence,the hydrogen medium returns to the inlet of the high-pressure section of the hydrogen compressor unit C1 by means of a twenty-ninth pipeline 29 after being reheated; the remaining flow is further cooled to 25°K and is connected to the throttle valve VI by means of the nineteenth pipeline 19 and is communicated with the gas-liquid separator D2 by means of the twentieth pipeline 20 after the throttle valve has been cooled to 20°K; after the gas-liquid separation, the liquid phase is communicated with the supercooling heat exchanger HX4 by means of the twenty-first pipeline 21,the liquid hydrogen returns to the gas-liquid separator D2 by means of the twenty-second pipeline 22 after being partially evaporated in the supercooling heat exchanger HX4 to form a thermosiphon loop; the gas phase of the gas-liquid separator D2 is communicated with the cryogenic heat exchanger HX3, the secondary precooling heat exchanger HX2 and the primary precooling heat exchanger HX1 by means of the twenty-third pipeline 23, the twenty-fourth pipeline 24 and the twenty-fifth pipeline 25 in sequence and then enters the low-pressure section of the hydrogen compressor unit C1 by means of the twenty-sixth pipeline 26 after being warmed up to the normal temperature,and then is combined with the medium-pressure hydrogen in the high-pressure section of the Cl hydrogen compressor unit after being supercharged by means of the low-pressure section of the Cl hydrogen compressor unit, so as to form a hydrogen refrigeration cycle assembly; ,

[0023] 3) Nitrogen at the outlet of the nitrogen compressor unit C2 enters the cold box precooling II by means of a thirtieth pipe 30, is cooled to 113°K by means of the primary precooling heat exchanger HX1, is communicated with the throttle valve V2 by means of the thirty-first pipe 31 and is communicated with the secondary precooling heat exchanger HX2 and the precooling heat exchanger primary HX1 by means of a thirty-second pipeline 32 and a thirty-third pipeline 33 in sequence after the throttle valve is cooled to 80°K, and then returns to the inlet of the nitrogen compressor unit C2 by means of a thirty-fourth pipeline 34, so as to form a set of nitrogen refrigeration cycle and provide cold energy for the temperature range of 113°K to 80°K and the medium of the nitrogen refrigeration cycle is pure nitrogen;

[0024] 4) The mixed refrigerant at the outlet of the mixed refrigerant compressor unit C3 enters the precooling cold box II and the primary precooling heat exchanger HX1 by means of a thirty-fifth pipeline 35 to be cooled to 113°K and is communicated with the throttling valve V3 by means of the thirty-sixth pipeline 36, returns to the primary precooling heat exchanger HX1 by means of a thirty-seventh pipeline 37 after the throttling valve has cooled, leaves the precooling cold box II by means of a thirty-eighth pipeline 38 and returns to the inlet of the mixed refrigerant compressor unit C3, so as to form a set of refrigeration cycles of the mixed refrigerant and provide cooling energy for the temperature range of 303°K to 113°K and the mixed refrigerant consists of methane, ethylene, propane, isopentane and of nitrogen.

[0025] The above embodiments constitute the specific implementation of the present invention. Many equivalent combinations or modifications can be made to the hydrogen refrigeration cycle, the nitrogen refrigeration cycle and the mixed refrigerant refrigeration cycle of the refrigerant hydrogen liquefaction device, all of which fall within the scope of the present invention.

Claims

1. Claims A mixed refrigerant hydrogen liquefaction device, wherein the device comprises a refrigerant compression unit (I), a pre-cooling cold box (II) and a cryogenic cold box (III) which are connected to each other by means of pipelines, wherein - the refrigerant compression unit (I) is provided with a dehydration molecular sieve adsorber (SI), a hydrogen compressor unit (Cl), a nitrogen compressor unit (C2) and a mixed refrigerant refrigeration unit (C3), - the precooling cold box (II) is provided with a primary precooling heat exchanger (HX1), a secondary precooling heat exchanger (HX2) and a low-temperature molecular sieve adsorber (S2) and - the cryogenic cold box (III) is provided with a cryogenic heat exchanger (HX3), an ejector (El), a supercooling heat exchanger (HX4), a gas-liquid separator (D2), a primary hydrogen expander (XI) and a secondary hydrogen expander (X2); characterized in that the dehydration molecular sieve adsorber (SI) in the refrigerant compression unit (I) is connected to a raw material hydrogen channel of the primary precooling heat exchanger (HX1) and the secondary precooling heat exchanger (HX2) and the low-temperature molecular sieve adsorber (S2) in the precooling cold box (II) by means of a second pipeline (2), a third pipeline (3) and a fourth pipeline (4), and then is connected to a raw material hydrogen channel of the cryogenic heat exchanger (HX3), the ejector (El) and a raw material hydrogen channel of the supercooling heat exchanger (HX4) in the cryogenic cold box (III), in sequence, by means of a fifth pipeline (5),of a sixth pipeline (6) and a seventh pipeline (7) to form a circulation channel in the entire process from raw hydrogen to liquid hydrogen, and in that, - the outlet of the hydrogen compressor unit (Cl) in the refrigerant compression unit (I) is connected to the supercharging ends of the primary hydrogen expander (XI) and the secondary hydrogen expander (X2) and to the high-pressure circulating hydrogen channels of the primary precooling heat exchanger (HX1) and the secondary precooling heat exchanger (HX2) in the precooling cold box (II) in sequence by means of an eleventh pipeline (11), a twelfth pipeline (12) and a thirteenth pipeline (13), and then is connected to a high-pressure circulating hydrogen channel of the cryogenic heat exchanger (HX3) in the cryogenic cold box (III) by means of a fourteenth pipeline (14) and is connected to the primary hydrogen expander (XI), the secondary hydrogen expander (X2) and to a throttle valve (VI) by means of a fifteenth pipe (15),of a seventeenth pipeline (17) and a nineteenth pipeline (19) among three bypass pipelines, respectively, the throttle valve (VI) is connected to the low-temperature circulating hydrogen channels of the gas-liquid separator (D2) and the supercooling heat exchanger in sequence (HX4) by means of a twentieth pipeline (20), a twenty-first pipeline (21) and a twenty-second pipeline (22), the gas-liquid separator (D2) is connected to a first low-pressure circulating hydrogen channel of the cryogenic heat exchanger (HX3), to the first low-pressure circulating hydrogen channels of the secondary precooling heat exchanger (HX2) and the primary precooling heat exchanger (HX1) and to a low-pressure section of the hydrogen compressor unit (Cl) in sequence by means of a twenty-third pipeline (23), a twenty-fourth pipeline (24),of a twenty-fifth pipe (25) and a twenty-sixth pipe (26), the primary hydrogen expander (XI) and the secondary hydrogen expander (X2) are connected to a second low-pressure circulating hydrogen channel of the cryogenic heat exchanger (HX3) by means of a sixteenth pipe (16) and an eighteenth pipe (18), respectively, and then is connected to the second low-pressure circulating hydrogen channels of the secondary pre-cooling heat exchanger (HX2) and, of the primary pre-cooling heat exchanger (HX1) and to a high-pressure section of the hydrogen compressor unit (Cl) by means of a twenty-seventh pipe (27), a twenty-eighth pipe (28) and a twenty-ninth pipe (29), in order to form a hydrogen refrigeration circulation channel.

2. The mixed refrigerant hydrogen liquefaction device according to claim 1, wherein the outlet of the nitrogen compressor unit (C2) is connected to a high-pressure nitrogen channel of the primary precooling heat exchanger (HX1) and a throttle valve (V2) in the precooling cold box (II) in sequence by means of a thirtieth pipeline (30) and a thirty-first pipeline (31), and then is connected to the inlets of the secondary precooling heat exchanger (HX2), the primary precooling heat exchanger (HX1) and the nitrogen compressor unit (C2) by means of a thirty-second pipeline (32),of a thirty-third pipe (33) and a thirty-fourth pipe (34) in sequence to form a nitrogen refrigeration circulation channel and the outlet of the mixed refrigerant compressor unit (C3) is connected to a high-pressure refrigerant channel of the primary precooling heat exchanger (HX1) and a throttle valve (V3) in the precooling cold box (II) by means of a thirty-fifth pipe (35) and a thirty-sixth pipe (36) in sequence, and then is connected to the inlets of the primary precooling heat exchanger (HX1) and the mixed refrigerant compressor unit (C3) by means of a thirty-seventh pipe (37) and a thirty-eighth pipe (38) in sequence to form a mixed refrigerant refrigeration circulation channel.,

3. A mixed refrigerant hydrogen liquefaction device according to claim 1, wherein the primary precooling heat exchanger (HX1), the secondary precooling heat exchanger (HX2), the cryogenic heat exchanger (HX3) and the supercooling heat exchanger (HX4) are all high-efficiency plate fin heat exchangers, the primary hydrogen expander (XI) and the secondary hydrogen expander (X2) are both centrifugal expanders braked by a supercharger, the section

4. The low pressure section of the hydrogen compressor unit (Cl) is a reciprocating compressor, the high pressure section of the hydrogen compressor unit (Cl) is a centrifugal compressor, and the nitrogen compressor unit (C2) and the mixed refrigerant compressor unit (C3) are centrifugal compressors. A method of using the mixed refrigerant hydrogen liquefaction device according to any one of claims 1 to 3, comprising the following steps: - the raw hydrogen is communicated with an inlet pipeline (1) of the dehydration molecular sieve adsorber (SI), removes water at 0.1 ppm, then enters the primary precooling heat exchanger (HX1) in the precooling cold box (II) by means of the second pipeline (2) to be cooled to 113°K, then enters the secondary precooling heat exchanger (HX2) filled with orthohydrogen-parahydrogen conversion catalysts by means of the third pipeline (3) for orthohydrogen-parahydrogen conversion to be cooled to 80°K; then enters the low-temperature molecular sieve adsorber (S2) by means of the fourth pipeline (4) to remove traces of oxygen, nitrogen, argon and methane,the material flow from the low-temperature adsorber communicates with the fifth pipeline (5) of the cryogenic cold box (III) and enters the cryogenic heat exchanger (HX3) filled with orthohydrogen and parahydrogen conversion catalysts to be cooled to 25°K, the material flow from (HX3) is communicated with the ejector (El) by means of the sixth pipeline (6) to reduce the pressure to 0.57 MPa, at the same time, the bog gas is introduced and enters the supercooling heat exchanger (HX4) filled with the orthohydrogen and parahydrogen conversion catalysts by means of the seventh pipeline (7) to be cooled to 22°K, then the throttle valve transfers the liquid hydrogen to a storage system and the bog in the storage system is reliquefied by means of the ejector (El);, - the outlet of the hydrogen compressor unit (Cl) is connected to the supercharging ends of the primary hydrogen expander (XI) and the secondary hydrogen expander (X2) by means of the eleventh pipe (11) in sequence and the high-pressure hydrogen is supercharged in sequence, then passes through the twelfth pipeline (12) and the thirteenth pipeline (13) in sequence and is cooled to 80°K in the pre-cooling cold box (II); the high-pressure hydrogen is communicated with the cryogenic heat exchanger (HX3) in the cryogenic cold box (III) by means of the fourteenth pipe (14), after the high-pressure hydrogen has been cooled to 70°K, a separate stream enters the primary hydrogen expander (XI) by means of the fifteenth pipe (15) to be cooled to 44.3°K, and then returns to the cryogenic heat exchanger (HX3) by means of the sixteenth pipe (16), after another separate stream has been cooled to 50°K, another separate stream enters the secondary hydrogen expander (X2) by means of the seventeenth pipe (17) to be cooled to 28.8°K,returns to the cryogenic heat exchanger (HX3) by means of the eighteenth pipe (18), then is combined with the flow at the outlet of the primary hydrogen expander (XI) after being reheated and passes through the cryogenic heat exchanger (HX3), then is communicated with the pre-cooling heat exchanger (HX2) and the pre-cooling heat exchanger (HX1) by means of a twenty-seventh pipe (27) and a twenty-eighth pipe (28) in sequence,the hydrogen medium returns to the inlet of the high-pressure section of the hydrogen compressor unit (Cl) by means of a twenty-ninth pipeline (29) after being reheated; the remaining flow is further cooled to 25°K and is connected to the throttle valve (VI) by means of the nineteenth pipeline (19) and is communicated with the gas-liquid separator (D2) by means of the twentieth pipeline (20) after the throttle valve has been cooled to 20°K; after the gas-liquid separation, the liquid phase is communicated with the supercooling heat exchanger (HX4) by means of the twenty-first pipeline (21),the liquid hydrogen returns to the gas-liquid separator (D2) by means of the twenty-second pipe (22) after having been partially evaporated in the supercooling heat exchanger (HX4) to form a thermosiphon loop; the gas phase of the gas-liquid separator (D2) is put into communication with the cryogenic heat exchanger, (HX3), the secondary pre-cooling heat exchanger (HX2) and the primary pre-cooling heat exchanger (HX1) by means of the twenty-third pipeline (23), the twenty-fourth pipeline (24) and the twenty-fifth pipeline (25) in sequence and then enters the low-pressure section of the hydrogen compressor unit (Cl) by means of the twenty-sixth pipeline (26) after being warmed up to the normal temperature, and then is combined with the medium-pressure hydrogen in the high-pressure section of the hydrogen compression unit (Cl) after being supercharged by means of the low-pressure section of the hydrogen compression unit (Cl), so as to form a set of hydrogen refrigeration cycle; - the nitrogen at the outlet of the nitrogen compressor unit (C2) enters the precooling cold box (II) by means of a thirtieth pipeline (30), is cooled to 113°K by means of the primary precooling heat exchanger (HX1), is communicated with the throttle valve (V2) by means of the thirty-first pipeline (31) and is communicated with the secondary precooling heat exchanger (HX2) and the primary precooling heat exchanger (HX1) by means of a thirty-second pipeline (32) and a thirty-third pipeline (33) in sequence after the throttle valve has been cooled to 80°K, and then returns to the inlet of the nitrogen compressor unit (C2) by means of a thirty-fourth pipeline (34), so as to form a whole refrigeration cycle nitrogen and provide cold energy for the temperature range of 113°K to 80°K. - the mixed refrigerant at the outlet of the mixed refrigerant compressor unit (C3) enters the precooling cold box (II) and the primary precooling heat exchanger (HX1) by means of a thirty-fifth pipe (35) to be cooled to 113°K and is communicated with the throttling valve (V3) by means of the thirty-sixth pipe (36), returns to the primary precooling heat exchanger (HX1) by means of a thirty-seventh pipe (37) after the throttling valve has cooled, leaves the precooling cold box (II) by means of a thirty-eighth pipe (38) and returns to the inlet of the compressor unit mixed refrigerant (C3), so as to form a set of mixed refrigerant refrigeration cycles and provide cooling energy for the temperature range of 303°K to 113°K.

5. A method of using the mixed refrigerant hydrogen liquefaction device according to claim 4, wherein the proportions of orthohydrogen and parahydrogen in step 1) are 2.2% and 97.8% respectively and the proportions of orthohydrogen and parahydrogen in the storage system are 1% and 99% respectively.

6. A method of using the mixed refrigerant hydrogen liquefaction device according to claim 4, wherein the nitrogen refrigeration cycle medium of step 3) is pure nitrogen.

7. A method of using the mixed refrigerant hydrogen liquefaction device according to claim 4, wherein the mixed refrigerant of step 4) consists of methane, ethylene, propane, isopentane and nitrogen.

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