A method and system for turbo-parallel pre-cooled hydrogen liquefaction

Abstract

This disclosure relates to a method and system for turbine parallel precooling hydrogen liquefaction. The method involves first-cycle nitrogen being compressed by a precooling compressor and cooled by a nitrogen cooler, then split into two streams. One stream is depressurized by a first expander to obtain cold nitrogen gas, while the other stream is heat-exchanged by a first heat exchanger and depressurized by a second expander before entering a second heat exchanger. The resulting second-cycle nitrogen is then mixed with the cold nitrogen gas and returned to the first heat exchanger. This precooling process precools the feedstock hydrogen to approximately 80K without affecting subsequent cryogenic and liquefaction units. Furthermore, the method allows for flexible adjustment of the inlet and outlet temperatures of the two heat exchangers, thereby reducing the temperature difference between them and minimizing irreversible heat loss. Additionally, nitrogen is used as the refrigerant throughout the precooling process, and the nitrogen is recycled throughout the process, further reducing the temperature difference between the heat exchangers, minimizing irreversible heat loss, and reducing process complexity.

Description

Technical Field

[0001] This disclosure relates to the field of hydrogen liquefaction technology, and more specifically, to a method and system for turbine parallel precooling hydrogen liquefaction. Background Technology

[0002] The complexity and high energy consumption of hydrogen liquefaction processes are the main problems limiting the large-scale development of the hydrogen liquefaction industry. Currently, the Cluade liquefaction process is commonly used as the mainstream route for large-scale hydrogen liquefaction, with energy consumption generally exceeding 12 kWh / kg·LH2. The Cluade liquefaction process uses liquid nitrogen to pre-cool hydrogen. Because the heat exchange between liquid nitrogen and hydrogen is a phase change heat transfer, the large temperature difference in the heat exchanger leads to significant irreversible losses and high system energy consumption. Summary of the Invention

[0003] The purpose of this disclosure is to provide a method and system for turbine parallel precooling hydrogen liquefaction to solve the problems of large heat exchange temperature difference and irreversible energy loss in the prior art.

[0004] To achieve the above objectives, the first aspect of this disclosure provides a method for turbine parallel precooling hydrogen liquefaction, the method comprising: The raw material hydrogen is introduced into the first heat exchanger to exchange heat with the first circulating nitrogen to obtain the first pre-cooled hydrogen; the first pre-cooled hydrogen is introduced into the second heat exchanger to exchange heat with the second circulating nitrogen to obtain the second pre-cooled hydrogen; the second pre-cooled hydrogen is processed sequentially through a cryogenic unit and a liquefaction unit to obtain liquid hydrogen. The first circulating nitrogen after heat exchange is compressed by a pre-cooling compressor and cooled by a nitrogen cooler to obtain compressed nitrogen; a portion of the compressed nitrogen is depressurized in a first expander to obtain cold nitrogen, and another portion of the compressed nitrogen is cooled by the first heat exchanger and depressurized by a second expander to obtain the second circulating nitrogen; the cold nitrogen is mixed with the second circulating nitrogen after heat exchange to form the first circulating nitrogen.

[0005] Optionally, the compressed nitrogen gas has a pressure of 20-30 bar and a temperature of 20-25°C.

[0006] Optionally, the flow rate ratio of compressed nitrogen entering the first expander and entering the first heat exchanger is (0.5-0.6):1.

[0007] Optionally, the temperature of the first circulating nitrogen is 160-168 K and the pressure is 1-1.5 bar; the temperature of the second circulating nitrogen is 78-85 K and the pressure is 1-1.5 bar.

[0008] Optionally, the temperature of the first precooled hydrogen is 160-168 K and the pressure is 21-25 bar; the temperature of the second precooled hydrogen is 78-85 K and the pressure is 21-25 bar.

[0009] Optionally, the cryogenic unit includes multiple cryogenic heat exchangers arranged in series, and the liquefaction unit includes one or more gas-liquid separators and multiple liquefaction heat exchangers arranged in series; the number of cryogenic heat exchangers is 2-10, and the number of liquefaction heat exchangers is 2-5. The method further includes passing the second precooled hydrogen through a plurality of the cryogenic heat exchangers and a plurality of the liquefaction heat exchangers in sequence, and then separating it through the gas-liquid separator to obtain the liquid hydrogen.

[0010] Optionally, the method further includes, The raw material hydrogen is subjected to auxiliary heat exchange treatment with an auxiliary heat exchange unit; the auxiliary heat exchange unit includes a first compressor, a first circulating hydrogen cooler, a second compressor, a second circulating hydrogen cooler, and a cryogenic expander unit; The auxiliary heat exchange treatment includes: The circulating hydrogen is sequentially compressed by the first compressor and cooled by the first circulating hydrogen cooler, and the resulting circulating hydrogen is sequentially passed through the first heat exchanger, the second heat exchanger, the cryogenic unit, and the liquefaction unit to exchange heat, thereby obtaining the first auxiliary heat exchange hydrogen; wherein, the flow order of the circulating hydrogen in the plurality of cryogenic heat exchangers and the plurality of liquefaction heat exchangers is the same as the flow order of the feed hydrogen; The first auxiliary heat exchange hydrogen is sequentially passed through the liquefaction unit, the cryogenic unit, the second heat exchanger, and the first heat exchanger for heat exchange, and the obtained first auxiliary heat exchange hydrogen is sequentially compressed by the second compressor and cooled by the second circulating hydrogen cooler before being returned to the first compressor; wherein, the flow order of the first auxiliary heat exchange hydrogen in the plurality of cryogenic heat exchangers and the plurality of liquefaction heat exchangers is opposite to the flow order of the raw material hydrogen; A portion of the circulating hydrogen after heat exchange in the first stage heat exchanger of the cryogenic unit is depressurized by the cryogenic expander as recooled circulating hydrogen, and the resulting second auxiliary heat exchange hydrogen is returned to the first compressor after heat exchange in sequence through the cryogenic unit, the second heat exchanger, and the first heat exchanger; wherein the flow order of the second auxiliary heat exchange hydrogen in the plurality of cryogenic heat exchangers is the opposite of the flow order of the feed hydrogen.

[0011] Optionally, the cryogenic expander unit includes multiple cryogenic expanders, and the number of cryogenic expanders is 2-5; The auxiliary heat exchange process further includes depressurizing the recooled cycle hydrogen in a partial cryogenic expander and exchanging heat with a partial cryogenic heat exchanger in the cryogenic unit, and then further depressurizing it in another part of the cryogenic expander to obtain the second auxiliary heat exchange hydrogen.

[0012] The second aspect of this disclosure provides a system for the turbine parallel precooling hydrogen liquefaction method described in the first aspect, the system comprising a first heat exchanger, a second heat exchanger, a first expander, a second expander, a precooling compressor, and a nitrogen cooler; The feed hydrogen inlet of the first heat exchanger is connected to the feed hydrogen source, the feed hydrogen outlet of the first heat exchanger is connected to the feed hydrogen inlet of the second heat exchanger, and the feed hydrogen outlet of the second heat exchanger is connected to the precooling hydrogen inlet of the cryogenic unit; the feed hydrogen outlet of the cryogenic unit is connected to the cryogenic hydrogen inlet of the liquefaction unit. The inlet of the precooling compressor is connected to the first circulating nitrogen outlet of the first heat exchanger, and the outlet of the precooling compressor is connected to the inlet of the nitrogen cooler; the outlet of the nitrogen cooler is connected to the inlet of the first expander and the compressed nitrogen inlet of the first heat exchanger, respectively. The compressed nitrogen outlet of the first heat exchanger is connected to the inlet of the second expander; the outlet of the second expander is connected to the second circulating nitrogen inlet of the second heat exchanger; the second circulating nitrogen outlet of the second heat exchanger and the outlet of the first expander are respectively connected to the first circulating nitrogen inlet of the first heat exchanger.

[0013] Optionally, the system further includes an auxiliary heat exchange unit, which includes a first compressor, a first circulating hydrogen cooler, a second compressor, a second circulating hydrogen cooler, and a cryogenic expander unit; The cryogenic unit includes multiple cryogenic heat exchangers arranged in series, and the liquefaction unit includes multiple liquefaction heat exchangers arranged in series. The outlet of the first compressor is connected to the inlet of the first circulating hydrogen cooler; the outlet of the first circulating hydrogen cooler is connected to the circulating hydrogen inlet of the first heat exchanger; the circulating hydrogen outlet of the first heat exchanger is connected to the circulating hydrogen inlet of the second heat exchanger; the circulating hydrogen outlet of the second heat exchanger is connected to the circulating hydrogen inlet of the cryogenic unit; the circulating hydrogen outlet of the cryogenic unit is connected to the circulating hydrogen inlet of the liquefaction unit; the circulating hydrogen outlet of the liquefaction unit is connected to the first auxiliary heat exchange hydrogen inlet of the liquefaction unit; the first auxiliary heat exchange hydrogen outlet of the liquefaction unit is connected to the first auxiliary heat exchange hydrogen inlet of the cryogenic unit; the first auxiliary heat exchange hydrogen outlet of the cryogenic unit is connected to the first auxiliary heat exchange hydrogen inlet of the second heat exchanger; the first auxiliary heat exchange hydrogen outlet of the second heat exchanger is connected to the first auxiliary heat exchange hydrogen inlet of the first heat exchanger; the first auxiliary heat exchange hydrogen outlet of the first heat exchanger is connected to the inlet of the second compressor; the outlet of the second compressor is connected to the inlet of the second circulating hydrogen cooler; the outlet of the second circulating hydrogen cooler is connected to the inlet of the first compressor. The first-stage cryogenic heat exchanger of the cryogenic unit has a recooling circulating hydrogen outlet on its circulating hydrogen outlet line, which is connected to the inlet of the cryogenic expander unit. The outlet of the cryogenic expander unit is connected to the second auxiliary heat exchange hydrogen inlet of the cryogenic unit, and the second auxiliary heat exchange hydrogen outlet of the cryogenic unit is connected to the second auxiliary heat exchange hydrogen inlet of the second heat exchanger. The second auxiliary heat exchange hydrogen outlet of the second heat exchanger is connected to the second auxiliary heat exchange hydrogen inlet of the first heat exchanger. The second auxiliary heat exchange hydrogen outlet of the first heat exchanger is connected to the inlet of the first compressor.

[0014] Through the above technical solution, the first circulating nitrogen is compressed by a pre-cooling compressor and cooled by a nitrogen cooler, then divided into two streams. One stream is depressurized by a first expander to obtain cold nitrogen gas, while the other stream is heat-exchanged by a first heat exchanger and depressurized by a second expander before entering the second heat exchanger for heat exchange. The resulting second circulating nitrogen is then mixed with the cold nitrogen gas and returned to the first heat exchanger. This pre-cools the raw hydrogen to approximately 80K, without affecting the subsequent cryogenic and liquefaction units. Furthermore, this disclosure employs two expanders connected in parallel, allowing for flexible adjustment of the inlet and outlet temperatures of the two heat exchangers, thereby reducing the temperature difference between the heat exchangers and minimizing irreversible heat loss. In addition, nitrogen is used as the refrigerant throughout the pre-cooling process, and the nitrogen is recycled throughout the process. Compared to the prior art using liquid nitrogen as the refrigerant, this not only further reduces the temperature difference between the heat exchangers and minimizes irreversible heat loss, but also eliminates the need for replenishing liquid nitrogen, reducing process complexity.

[0015] Other features and advantages of this disclosure will be described in detail in the following detailed description section. Attached Figure Description

[0016] The accompanying drawings are provided to further illustrate the present disclosure and form part of the specification. They are used together with the following detailed description to explain the present disclosure, but do not constitute a limitation thereof. In the drawings: Figure 1 This is a schematic diagram of a turbine-parallel precooled hydrogen liquefaction system disclosed herein.

[0017] Explanation of reference numerals in the attached figures A. Raw material hydrogen; B. Gas-liquid separator; C. Liquid hydrogen; H1. Nitrogen cooler; C3. Pre-cooling compressor; T1. First expander; T2. Second expander; T3. Third expander; T4. Fourth expander; T5. Fifth expander; C1. Second compressor; C2. First compressor; H2. First circulating hydrogen cooler; H3. Second circulating hydrogen cooler; HX1. First heat exchanger; HX2. Second heat exchanger; HX3. Third heat exchanger; HX4. Fourth heat exchanger; HX5. Fifth heat exchanger; HX6. Sixth heat exchanger; HX7. Seventh heat exchanger; HX8. Eighth heat exchanger. Detailed Implementation

[0018] The specific embodiments of this disclosure will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit this disclosure.

[0019] like Figure 1 As shown, the first aspect of this disclosure provides a method for turbine parallel precooling hydrogen liquefaction, the method comprising: The raw material hydrogen is introduced into the first heat exchanger to exchange heat with the first circulating nitrogen to obtain the first pre-cooled hydrogen; the first pre-cooled hydrogen is introduced into the second heat exchanger to exchange heat with the second circulating nitrogen to obtain the second pre-cooled hydrogen; the second pre-cooled hydrogen is processed sequentially through a cryogenic unit and a liquefaction unit to obtain liquid hydrogen. The first circulating nitrogen after heat exchange is compressed by a pre-cooling compressor and cooled by a nitrogen cooler to obtain compressed nitrogen; a portion of the compressed nitrogen is depressurized in a first expander to obtain cold nitrogen, and another portion of the compressed nitrogen is cooled by the first heat exchanger and depressurized by a second expander to obtain the second circulating nitrogen; the cold nitrogen is mixed with the second circulating nitrogen after heat exchange to form the first circulating nitrogen.

[0020] Through the above technical solution, the first circulating nitrogen is compressed by a pre-cooling compressor and cooled by a nitrogen cooler, then divided into two streams. One stream is depressurized by a first expander to obtain cold nitrogen gas, while the other stream is heat-exchanged by a first heat exchanger and depressurized by a second expander before entering the second heat exchanger for heat exchange. The resulting second circulating nitrogen is then mixed with the cold nitrogen gas and returned to the first heat exchanger. This pre-cools the raw hydrogen to approximately 80K, without affecting the subsequent cryogenic and liquefaction units. Furthermore, this disclosure employs two expanders connected in parallel, allowing for flexible adjustment of the inlet and outlet temperatures of the two heat exchangers, thereby reducing the temperature difference between the heat exchangers and minimizing irreversible heat loss. In addition, nitrogen is used as the refrigerant throughout the pre-cooling process, and the nitrogen is recycled throughout the process. Compared to the prior art using liquid nitrogen as the refrigerant, this not only further reduces the temperature difference between the heat exchangers and minimizes irreversible heat loss, but also eliminates the need for replenishing liquid nitrogen, reducing process complexity.

[0021] In one embodiment, the compressed nitrogen gas has a pressure of 20-30 bar and a temperature of 20-25°C. In this embodiment, the first-cycle nitrogen after heat exchange is compressed to a suitable pressure by a pre-cooling compressor C3. The temperature of the compressed nitrogen gas will rise, and then it will be cooled to room temperature by a nitrogen cooler H1, so that it can be cooled to a suitable temperature by a subsequent expander.

[0022] In one embodiment, the flow rate ratio of compressed nitrogen entering the first expander T1 and the flow rate entering the first heat exchanger HX1 is (0.5-0.6):1.

[0023] In a preferred embodiment, the flow rate ratio of compressed nitrogen entering the first expander T1 and the flow rate entering the first heat exchanger HX1 is (0.53-0.58):1.

[0024] In this embodiment, compressed nitrogen is split into two streams. One stream is depressurized by the first expander T1, causing a rapid decrease in nitrogen temperature. The other stream undergoes heat exchange in the first heat exchanger HX1 and then enters the second expander T2 for further depressurization and cooling. During the precooling process, the compressed nitrogen entering the first heat exchanger HX1 has a higher temperature than the first circulating nitrogen. The temperatures of the compressed nitrogen at the inlets of the first and second expanders T1 differ, resulting in a lower temperature for the second circulating nitrogen compared to the first circulating nitrogen. Consequently, the preheating source temperature of the second heat exchanger HX2 is lower than that of the first heat exchanger HX1. In other words, the preheating source of the first heat exchanger HX1 consists of the first circulating nitrogen and a portion of the compressed nitrogen, while the preheating source of the second heat exchanger HX2 consists of the second circulating nitrogen. By adjusting the flow ratio of the compressed nitrogen entering the first expander T1 and the first heat exchanger HX1, the temperatures of the preheating sources of the first and second heat exchangers HX1 and HX2 can be flexibly adjusted, thereby regulating the heat exchange effect of the feedstock hydrogen.

[0025] In one embodiment, the temperature of the first circulating nitrogen is 160-168 K and the pressure is 1-1.5 bar.

[0026] In a preferred embodiment, the temperature of the first circulating nitrogen is 161-165 K and the pressure is 1.1-1.4 bar.

[0027] In one embodiment, the temperature of the first precooled hydrogen is 160-168 kJ and the pressure is 21-25 bar.

[0028] In a preferred embodiment, the temperature of the first precooled hydrogen is 161-165 K and the pressure is 22-24 bar.

[0029] In one embodiment, the temperature of the second circulating nitrogen is 78-85 K and the pressure is 1-1.5 bar.

[0030] In a preferred embodiment, the temperature of the second circulating nitrogen is 80-83 K and the pressure is 1.1-1.4 bar.

[0031] In one embodiment, the temperature of the second precooled hydrogen is 78-85 K and the pressure is 21-25 bar.

[0032] In a preferred embodiment, the temperature of the second precooled hydrogen is 80-83K and the pressure is 22-24bar.

[0033] In this embodiment, when the temperature of the first circulating nitrogen is within a suitable range, the temperature difference between the first circulating nitrogen and the raw material hydrogen is smaller compared to the existing precooling method using liquid nitrogen, which can further reduce system energy consumption. Simultaneously, the first precooled hydrogen obtained after heat exchange has a higher temperature compared to the existing precooling method using liquid nitrogen. When using the lower-temperature second circulating nitrogen, the temperature of the second precooled hydrogen can still be reduced to around 80K, without affecting the parameters of the subsequent cryogenic and liquefaction units.

[0034] In one embodiment, the cryogenic unit includes a plurality of cryogenic heat exchangers arranged in series, wherein the number of cryogenic heat exchangers is 2-10.

[0035] In this embodiment, the series arrangement described in this disclosure refers to the connection of the same material flow channels of two adjacent cryogenic heat exchangers. For example, the raw material hydrogen after heat exchange in the second heat exchanger HX2 can be heat exchanged sequentially through the raw material hydrogen channel of the first stage cryogenic heat exchanger, the next stage cryogenic heat exchanger, the next stage cryogenic heat exchanger, and so on, until the last stage cryogenic heat exchanger.

[0036] In a preferred embodiment, the number of cryogenic heat exchangers is four, and they are arranged in the order of the raw material hydrogen flow as the third heat exchanger HX3, the fourth heat exchanger HX4, the fifth heat exchanger HX5, and the sixth heat exchanger HX6.

[0037] In one embodiment, the liquefaction unit includes a plurality of liquefaction heat exchangers arranged in series, wherein the number of liquefaction heat exchangers is 2-5.

[0038] In this embodiment, the series arrangement described in this disclosure refers to the connection of the same material flow channels of two adjacent liquefaction heat exchangers. For example, the raw material hydrogen after heat exchange in the sixth heat exchanger HX6 can be heat exchanged sequentially through the raw material hydrogen channel of the first-stage liquefaction heat exchanger, the next-stage liquefaction heat exchanger, the next-stage liquefaction heat exchanger, and so on, until the last-stage liquefaction heat exchanger.

[0039] In a preferred embodiment, there are two liquefaction heat exchangers, which are arranged in the order of the raw material hydrogen flow as the seventh heat exchanger HX7 and the eighth heat exchanger HX8.

[0040] In one embodiment, the liquefaction unit of this disclosure further includes one or more gas-liquid separators for separating liquid hydrogen and the liquefied gas phase. The arrangement of the multiple gas-liquid separators can be flexibly selected according to actual production needs; the multiple gas-liquid separators can be arranged in series or in parallel.

[0041] In one embodiment, the gas-liquid separator used in this disclosure is a conventional choice in the art, and this application does not make any special requirements. For example, the gas-liquid separator is a flash tank.

[0042] In one embodiment, the present disclosure provides an expansion valve on the inlet pipeline of the gas-liquid separator, which can reduce the pressure of the raw hydrogen at the raw hydrogen outlet of the liquefaction unit when the temperature is not low enough, thereby reducing the temperature of the raw hydrogen entering the gas-liquid separator.

[0043] In one embodiment, the method further includes passing the second precooled hydrogen through a plurality of cryogenic heat exchangers and a plurality of liquefaction heat exchangers in sequence, and then separating it through the gas-liquid separator to obtain the liquid hydrogen.

[0044] In one specific embodiment, the second pre-cooled hydrogen is sequentially passed through a third heat exchanger HX3, a fourth heat exchanger HX4, a fifth heat exchanger HX5, a sixth heat exchanger HX6, a seventh heat exchanger HX7, and an eighth heat exchanger HX8 for heat exchange, and then separated by the gas-liquid separator to obtain the liquid hydrogen.

[0045] In one embodiment, the method further includes performing auxiliary heat exchange treatment between the raw material hydrogen and an auxiliary heat exchange unit; the auxiliary heat exchange unit includes a first compressor C2, a first circulating hydrogen cooler H2, a second compressor C1, a second circulating hydrogen cooler H3, and a cryogenic expander unit; The auxiliary heat exchange treatment includes: The circulating hydrogen is sequentially compressed by the first compressor C2 and cooled by the first circulating hydrogen cooler H2, and the resulting circulating hydrogen is sequentially heat-exchanged through the first heat exchanger HX1, the second heat exchanger HX2, the cryogenic unit, and the liquefaction unit to obtain the first auxiliary heat exchange hydrogen; wherein, the flow order of the circulating hydrogen in the multiple cryogenic heat exchangers and the multiple liquefaction heat exchangers is the same as the flow order of the raw material hydrogen; The first auxiliary heat exchange hydrogen is sequentially passed through the liquefaction unit, the cryogenic unit, the second heat exchanger HX2, and the first heat exchanger HX1 for heat exchange, and the obtained first auxiliary heat exchange hydrogen is sequentially compressed by the second compressor C1 and cooled by the second circulating hydrogen cooler H3 before returning to the first compressor C2; wherein, the flow order of the first auxiliary heat exchange hydrogen in the multiple cryogenic heat exchangers and the multiple liquefaction heat exchangers is the opposite of the flow order of the feed hydrogen; A portion of the circulating hydrogen after heat exchange in the first stage heat exchanger of the cryogenic unit is depressurized as recooled circulating hydrogen in the cryogenic expander unit, and the resulting second auxiliary heat exchange hydrogen is returned to the first compressor C2 after heat exchange in sequence through the cryogenic unit, the second heat exchanger HX2, and the first heat exchanger HX1; wherein, the flow order of the second auxiliary heat exchange hydrogen in the multiple cryogenic heat exchangers is the opposite of the flow order of the feed hydrogen.

[0046] In this disclosure, "flow sequence identical to that of the feedstock hydrogen" means that a certain stream flows sequentially through the third heat exchanger HX3, the fourth heat exchanger HX4, the fifth heat exchanger HX5, the sixth heat exchanger HX6, the seventh heat exchanger HX7, and the eighth heat exchanger HX8. "Flow sequence opposite to that of the feedstock hydrogen" means that a certain stream flows sequentially through the eighth heat exchanger HX8, the seventh heat exchanger HX7, the sixth heat exchanger HX6, the fifth heat exchanger HX5, the fourth heat exchanger HX4, and the third heat exchanger HX3. The starting point for both the flow sequence identical to and opposite to that of the feedstock hydrogen can be any one of the following heat exchangers: third heat exchanger HX3, fourth heat exchanger HX4, fifth heat exchanger HX5, sixth heat exchanger HX6, seventh heat exchanger HX7, and eighth heat exchanger HX8.

[0047] In one embodiment, the cryogenic expander unit includes multiple cryogenic expanders, and the number of cryogenic expanders is 2-5.

[0048] In one specific implementation, there are three cryogenic expanders: a third expander T3, a fourth expander T4, and a fifth expander T5.

[0049] In one embodiment, the auxiliary heat exchange process further includes depressurizing the recooled cycle hydrogen in a partial cryogenic expander, exchanging heat with a partial cryogenic heat exchanger in the cryogenic unit, and then further depressurizing it in another partial cryogenic expander to obtain the second auxiliary heat exchange hydrogen.

[0050] In one specific embodiment, the recooled cycle hydrogen is depressurized by the third expander T3 and then enters the fifth heat exchanger HX5 for heat exchange. The obtained recooled cycle hydrogen is then depressurized sequentially by the fourth expander T4 and the fifth expander T5 to obtain the second auxiliary heat exchange hydrogen.

[0051] In one specific embodiment, the circulating hydrogen is sequentially compressed by the first compressor C2 and cooled by the first circulating hydrogen cooler H2. The resulting circulating hydrogen is then sequentially heat-exchanged by the first heat exchanger HX1, the second heat exchanger HX2, the third heat exchanger HX3, the fourth heat exchanger HX4, the fifth heat exchanger HX5, the sixth heat exchanger HX6, the seventh heat exchanger HX7, and the eighth heat exchanger HX8 to obtain the first auxiliary heat exchange hydrogen. The first auxiliary heat exchange hydrogen is then sequentially heat-exchanged by the seventh heat exchanger HX7, the sixth heat exchanger HX6, the fifth heat exchanger HX5, the fourth heat exchanger HX4, the third heat exchanger HX3, the second heat exchanger HX2, and the first heat exchanger HX1, and then sequentially compressed by the second compressor C1 and cooled by the second circulating hydrogen cooler H3 before returning to the first compressor C2. The circulating hydrogen, after being heated by the third heat exchanger HX3, is depressurized by the third expander T3 and then enters the fifth heat exchanger HX5 for further heat exchange. It is then cooled sequentially by the fourth expander T4 and the fifth expander T5. The resulting second auxiliary heat exchange hydrogen is then returned to the first compressor C2 after being heated in the order of the sixth heat exchanger HX6, the fifth heat exchanger HX5, the fourth heat exchanger HX4, the third heat exchanger HX3, the second heat exchanger HX2, and the first heat exchanger HX1.

[0052] In one embodiment, the first heat exchanger HX1, the second heat exchanger HX2, the cryogenic heat exchanger, and the liquefaction heat exchanger used in this disclosure are conventional choices in the art, and this application does not make any special requirements.

[0053] In one embodiment, the first expander T1, the second expander T2, the third expander T3, the fourth expander T4, and the fifth expander T5 used in this disclosure are conventional choices in the art, and this application does not make any special requirements, as long as they can reduce the pressure of the hydrogen passing through them.

[0054] In one embodiment, the precooling compressor C3, the first compressor C2, and the second compressor C1 used in this disclosure are conventional choices in the art, and this application does not make any special requirements, as long as they can pressurize the hydrogen passing through them.

[0055] In one embodiment, the nitrogen cooler H1, the first circulating hydrogen cooler H2, and the second circulating hydrogen cooler H3 used in this disclosure are conventional choices in the art, and this application does not make any special requirements, as long as they can cool the materials passing through them.

[0056] In one embodiment, flow regulating valves can be installed on suitable pipelines to regulate the flow rate and pressure of each pipeline. For example, flow regulating valves can be installed on the inlet pipelines of the first expander T1 and the second expander T2, respectively, and on suitable pipelines of the auxiliary heat exchange unit to flexibly regulate the flow rate of nitrogen entering the first expander T1 and the second expander T2. Flow regulating valves can be installed on the raw material hydrogen inlet pipeline and / or raw material hydrogen outlet pipeline of the eighth heat exchanger HX8 to further regulate the temperature of the material entering the gas-liquid separator.

[0057] like Figure 1 As shown, the second aspect of this disclosure provides a system for the method described in the first aspect, the system comprising a first heat exchanger HX1, a second heat exchanger HX2, a first expander T1, a second expander T2, a precooling compressor C3, and a nitrogen cooler H1; The feed hydrogen inlet of the first heat exchanger HX1 is connected to the feed hydrogen source, the feed hydrogen outlet of the first heat exchanger HX1 is connected to the feed hydrogen inlet of the second heat exchanger HX2, and the feed hydrogen outlet of the second heat exchanger HX2 is connected to the feed hydrogen inlet of the cryogenic unit; the feed hydrogen outlet of the cryogenic unit is connected to the feed hydrogen inlet of the liquefaction unit. The inlet of the precooling compressor C3 is connected to the first circulating nitrogen outlet of the first heat exchanger HX1, and the outlet of the precooling compressor C3 is connected to the inlet of the nitrogen cooler H1; the outlet of the nitrogen cooler H1 is connected to the inlet of the first expander T1 and the compressed nitrogen inlet of the first heat exchanger HX1, respectively. The compressed nitrogen outlet of the first heat exchanger HX1 is connected to the inlet of the second expander T2; the outlet of the second expander T2 is connected to the second circulating nitrogen inlet of the second heat exchanger HX2; the second circulating nitrogen outlet of the second heat exchanger HX2 and the outlet of the first expander T1 are respectively connected to the first circulating nitrogen inlet of the first heat exchanger HX1.

[0058] The system also includes an auxiliary heat exchange unit, which includes a first compressor C2, a first circulating hydrogen cooler H2, a second compressor C1, a second circulating hydrogen cooler H3, and a cryogenic expander unit, wherein the number of cryogenic expanders in the cryogenic expander unit is 2-5. The cryogenic unit includes multiple cryogenic heat exchangers arranged in series, and the liquefaction unit includes one or more gas-liquid separators and multiple liquefaction heat exchangers arranged in series; the number of cryogenic heat exchangers is 2-10, and the number of liquefaction heat exchangers is 2-5. The outlet of the first compressor C2 is connected to the inlet of the first circulating hydrogen cooler H2; the outlet of the first circulating hydrogen cooler H2 is connected to the circulating hydrogen inlet of the first heat exchanger HX1; the circulating hydrogen outlet of the first heat exchanger HX1 is connected to the circulating hydrogen inlet of the second heat exchanger HX2; the circulating hydrogen outlet of the second heat exchanger HX2 is connected to the circulating hydrogen inlet of the cryogenic unit; the circulating hydrogen outlet of the cryogenic unit is connected to the circulating hydrogen inlet of the liquefaction unit; the circulating hydrogen outlet of the liquefaction unit is connected to the first auxiliary heat exchange hydrogen inlet of the liquefaction unit; the first auxiliary heat exchange hydrogen inlet of the liquefaction unit... The hot hydrogen outlet is connected to the first auxiliary heat exchange hydrogen inlet of the cryogenic unit; the first auxiliary heat exchange hydrogen outlet of the cryogenic unit is connected to the first auxiliary heat exchange hydrogen inlet of the second heat exchanger HX2; the first auxiliary heat exchange hydrogen outlet of the second heat exchanger HX2 is connected to the first auxiliary heat exchange hydrogen inlet of the first heat exchanger HX1; the first auxiliary heat exchange hydrogen outlet of the first heat exchanger HX1 is connected to the inlet of the second compressor C1; the outlet of the second compressor C1 is connected to the inlet of the second circulating hydrogen cooler H3; the outlet of the second circulating hydrogen cooler H3 is connected to the inlet of the first compressor C2. The first-stage cryogenic heat exchanger of the cryogenic unit has a recooling circulating hydrogen outlet on its circulating hydrogen outlet line, which is connected to the inlet of the cryogenic expander unit. The outlet of the cryogenic expander unit is connected to the second auxiliary heat exchange hydrogen inlet of the cryogenic unit, and the second auxiliary heat exchange hydrogen outlet of the cryogenic unit is connected to the second auxiliary heat exchange hydrogen inlet of the second heat exchanger HX2. The second auxiliary heat exchange hydrogen outlet of the second heat exchanger HX2 is connected to the second auxiliary heat exchange hydrogen inlet of the first heat exchanger HX1. The second auxiliary heat exchange hydrogen outlet of the first heat exchanger HX1 is connected to the inlet of the first compressor C2.

[0059] In one specific embodiment, the cryogenic unit includes a third heat exchanger HX3, a fourth heat exchanger HX4, a fifth heat exchanger HX5, and a sixth heat exchanger HX6. The auxiliary heat exchange unit includes a third expander T3, a fourth expander T4, a fifth expander T5, a first compressor C2, a second compressor C1, a first circulating hydrogen cooler H2, and a second circulating hydrogen cooler H3; The liquefaction unit includes a seventh heat exchanger HX7, an eighth heat exchanger HX8, and a gas-liquid separator. The outlet of the first compressor C2 is connected to the inlet of the first circulating hydrogen cooler H2; the outlet of the first circulating hydrogen cooler H2 is connected to the circulating hydrogen inlet of the first heat exchanger HX1; the circulating hydrogen outlet of the first heat exchanger HX1 is connected to the circulating hydrogen inlet of the second heat exchanger HX2; the circulating hydrogen outlet of the second heat exchanger HX2 is connected to the circulating hydrogen inlet of the third heat exchanger HX3; the circulating hydrogen outlet of the third heat exchanger HX3 is connected to the circulating hydrogen inlet of the fourth heat exchanger HX4 and the inlet of the third expander T3, respectively. The outlet of the third expander T3 is connected to the recooling cycle hydrogen inlet of the fifth heat exchanger HX5; the recooling cycle hydrogen outlet of the fifth heat exchanger HX5 is connected to the inlet of the fourth expander T4; the outlet of the fourth expander T4 is connected to the inlet of the fifth expander T5; the outlet of the fifth expander T5 is connected to the second auxiliary heat exchange hydrogen inlet of the sixth heat exchanger HX6; the second auxiliary heat exchange hydrogen outlet of the sixth heat exchanger HX6 is connected to the second auxiliary heat exchange hydrogen inlet of the fifth heat exchanger HX5; the second auxiliary heat exchange hydrogen outlet of the fifth heat exchanger HX5 is connected to the second auxiliary heat exchange hydrogen inlet of the fourth heat exchanger HX4; the second auxiliary heat exchange hydrogen outlet of the fourth heat exchanger HX4 is connected to the second auxiliary heat exchange hydrogen inlet of the third heat exchanger HX3; the second auxiliary heat exchange hydrogen outlet of the third heat exchanger HX3 is connected to the second auxiliary heat exchange hydrogen inlet of the second heat exchanger HX2; the second auxiliary heat exchange hydrogen outlet of the second heat exchanger HX2 is connected to the second auxiliary heat exchange hydrogen inlet of the first heat exchanger HX1. The circulating hydrogen outlet of the fourth heat exchanger HX4 is connected to the circulating hydrogen inlet of the fifth heat exchanger HX5; the circulating hydrogen outlet of the fifth heat exchanger HX5 is connected to the circulating hydrogen inlet of the sixth heat exchanger HX6; the circulating hydrogen outlet of the sixth heat exchanger HX6 is connected to the circulating hydrogen inlet of the seventh heat exchanger HX7; the circulating hydrogen outlet of the seventh heat exchanger HX7 is connected to the circulating hydrogen inlet of the eighth heat exchanger HX8; the circulating hydrogen outlet of the eighth heat exchanger HX8 is connected to the first auxiliary heat exchange hydrogen inlet of the seventh heat exchanger HX7; the first auxiliary heat exchange hydrogen outlet of the seventh heat exchanger HX7 is connected to the first auxiliary heat exchange hydrogen inlet of the sixth heat exchanger HX6; the first auxiliary heat exchange hydrogen outlet of the sixth heat exchanger HX6 is connected to the circulating hydrogen inlet of the fifth heat exchanger HX5. The first auxiliary heat exchange hydrogen inlet of the fifth heat exchanger HX5 is connected; the first auxiliary heat exchange hydrogen outlet of the fifth heat exchanger HX5 is connected to the first auxiliary heat exchange hydrogen inlet of the fourth heat exchanger HX4; the first auxiliary heat exchange hydrogen outlet of the fourth heat exchanger HX4 is connected to the first auxiliary heat exchange hydrogen inlet of the third heat exchanger HX3; the first auxiliary heat exchange hydrogen outlet of the third heat exchanger HX3 is connected to the first auxiliary heat exchange hydrogen inlet of the second heat exchanger HX2; the first auxiliary heat exchange hydrogen outlet of the second heat exchanger HX2 is connected to the first auxiliary heat exchange hydrogen inlet of the first heat exchanger HX1; the first auxiliary heat exchange hydrogen outlet of the first heat exchanger HX1 is connected to the inlet of the second compressor C1; the outlet of the second compressor C1 is connected to the inlet of the second circulating hydrogen cooler H3. The outlet of the second circulating hydrogen cooler H3 and the second auxiliary heat exchange hydrogen outlet of the first heat exchanger HX1 are respectively connected.

[0060] The method and system disclosed herein can pre-cool the raw hydrogen to approximately 80K, without affecting subsequent cryogenic and liquefaction units. Furthermore, this disclosure employs two parallel expanders, allowing for flexible adjustment of the inlet and outlet temperatures of the two heat exchangers, thereby reducing the temperature difference between the heat exchangers and minimizing irreversible heat loss. Compared to existing mainstream hydrogen liquefaction processes, simulation results show that the method disclosed herein can reduce system energy consumption from over 12-15 kWh / kg·LH2 to 8.5-9.5 kWh / kg·LH2. In addition, nitrogen is used as the refrigerant throughout the pre-cooling process, and the nitrogen is recycled throughout the process. Compared to the use of liquid nitrogen as the refrigerant in existing technologies, this not only further reduces the temperature difference between the heat exchangers and minimizes irreversible heat loss, but also eliminates the need for replenishing liquid nitrogen, reducing process complexity.

[0061] The preferred embodiments of the present disclosure have been described in detail above with reference to the accompanying drawings. However, the present disclosure is not limited to the specific details of the above embodiments. Within the scope of the technical concept of the present disclosure, various simple modifications can be made to the technical solutions of the present disclosure, and these simple modifications all fall within the protection scope of the present disclosure.

[0062] It should also be noted that the various specific technical features described in the above embodiments can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, this disclosure will not describe the various possible combinations separately.

[0063] Furthermore, various different embodiments of this disclosure can be combined in any way, as long as they do not violate the spirit of this disclosure, they should also be regarded as the content disclosed in this disclosure.

Claims

1. A method of turbo-parallel pre-cooled hydrogen liquefaction, characterized in that, The method includes: The raw material hydrogen is introduced into the first heat exchanger (HX1) to exchange heat with the first circulating nitrogen to obtain the first pre-cooled hydrogen; the first pre-cooled hydrogen is introduced into the second heat exchanger (HX2) to exchange heat with the second circulating nitrogen to obtain the second pre-cooled hydrogen; the second pre-cooled hydrogen is then processed sequentially through a cryogenic unit and a liquefaction unit to obtain liquid hydrogen. The first circulating nitrogen after heat exchange is compressed by a pre-cooling compressor (C3) and cooled by a nitrogen cooler (H1) to obtain compressed nitrogen. A portion of the compressed nitrogen is depressurized in a first expander (T1) to obtain cold nitrogen. Another portion of the compressed nitrogen is cooled by a first heat exchanger (HX1) and depressurized by a second expander (T2) to obtain the second circulating nitrogen. The cold nitrogen is mixed with the second circulating nitrogen after heat exchange to form the first circulating nitrogen.

2. The method of claim 1, wherein, The compressed nitrogen gas has a pressure of 20-30 bar and a temperature of 20-25°C.

3. The method of claim 1, wherein, The flow rate ratio of compressed nitrogen entering the first expander (T1) and the first heat exchanger (HX1) is (0.5-0.6):

1.

4. The method of claim 1, wherein, The temperature of the first circulating nitrogen is 160-168 K, and the pressure is 1-1.5 bar; The temperature of the second circulating nitrogen is 78-85 K, and the pressure is 1-1.5 bar.

5. The method of claim 1, wherein, The temperature of the first precooled hydrogen is 160-168K, and the pressure is 21-25bar. The temperature of the second precooled hydrogen is 78-85K, and the pressure is 21-25bar.

6. The method of claim 1, wherein, The cryogenic unit includes multiple cryogenic heat exchangers arranged in series, and the liquefaction unit includes one or more gas-liquid separators and multiple liquefaction heat exchangers arranged in series; the number of cryogenic heat exchangers is 2-10, and the number of liquefaction heat exchangers is 2-5. The method further includes passing the second precooled hydrogen through a plurality of the cryogenic heat exchangers and a plurality of the liquefaction heat exchangers in sequence, and then separating it through the gas-liquid separator to obtain the liquid hydrogen.

7. The method of claim 6, wherein, The method further includes performing auxiliary heat exchange treatment between the raw material hydrogen and an auxiliary heat exchange unit; the auxiliary heat exchange unit includes a first compressor (C2), a first circulating hydrogen cooler (H2), a second compressor (C1), a second circulating hydrogen cooler (H3), and a cryogenic expander unit; The auxiliary heat exchange treatment includes: The circulating hydrogen is sequentially compressed by the first compressor (C2) and cooled by the first circulating hydrogen cooler (H2), and the resulting circulating hydrogen is sequentially passed through the first heat exchanger (HX1), the second heat exchanger (HX2), the cryogenic unit, and the liquefaction unit to exchange heat, thereby obtaining the first auxiliary heat exchange hydrogen; wherein, the flow order of the circulating hydrogen in the plurality of cryogenic heat exchangers and the plurality of liquefaction heat exchangers is the same as the flow order of the feed hydrogen; The first auxiliary heat exchange hydrogen is sequentially passed through the liquefaction unit, the cryogenic unit, the second heat exchanger (HX2), and the first heat exchanger (HX1) for heat exchange. The obtained first auxiliary heat exchange hydrogen is then sequentially compressed by the second compressor (C1) and cooled by the second circulating hydrogen cooler (H3) before returning to the first compressor (C2). The flow order of the first auxiliary heat exchange hydrogen in the multiple cryogenic heat exchangers and the multiple liquefaction heat exchangers is the opposite of the flow order of the feed hydrogen. A portion of the circulating hydrogen after heat exchange in the first stage heat exchanger of the cryogenic unit is depressurized as recooled circulating hydrogen in the cryogenic expander unit, and the resulting second auxiliary heat exchange hydrogen is returned to the first compressor (C2) after heat exchange in sequence through the cryogenic unit, the second heat exchanger (HX2), and the first heat exchanger (HX1); wherein the flow order of the second auxiliary heat exchange hydrogen in the plurality of cryogenic heat exchangers is the opposite of the flow order of the feed hydrogen.

8. The method of claim 7, wherein, The cryogenic expander unit includes multiple cryogenic expanders, and the number of cryogenic expanders is 2-5. The auxiliary heat exchange process further includes depressurizing the recooled cycle hydrogen in a partial cryogenic expander and exchanging heat with a partial cryogenic heat exchanger in the cryogenic unit, and then further depressurizing it in another part of the cryogenic expander to obtain the second auxiliary heat exchange hydrogen.

9. A system for a turbine parallel precooling hydrogen liquefaction method according to any one of claims 1 to 8, characterized in that, The system includes a first heat exchanger (HX1), a second heat exchanger (HX2), a first expander (T1), a second expander (T2), a precooling compressor (C3), and a nitrogen cooler (H1); The feed hydrogen inlet of the first heat exchanger (HX1) is connected to the feed hydrogen source, the feed hydrogen outlet of the first heat exchanger (HX1) is connected to the feed hydrogen inlet of the second heat exchanger (HX2), and the feed hydrogen outlet of the second heat exchanger (HX2) is connected to the feed hydrogen inlet of the cryogenic unit; the feed hydrogen outlet of the cryogenic unit is connected to the feed hydrogen inlet of the liquefaction unit. The inlet of the precooling compressor (C3) is connected to the first circulating nitrogen outlet of the first heat exchanger (HX1), and the outlet of the precooling compressor (C3) is connected to the inlet of the nitrogen cooler (H1); the outlet of the nitrogen cooler (H1) is connected to the inlet of the first expander (T1) and the compressed nitrogen inlet of the first heat exchanger (HX1), respectively. The compressed nitrogen outlet of the first heat exchanger (HX1) is connected to the inlet of the second expander (T2); the outlet of the second expander (T2) is connected to the second circulating nitrogen inlet of the second heat exchanger (HX2); the second circulating nitrogen outlet of the second heat exchanger (HX2) and the outlet of the first expander (T1) are respectively connected to the first circulating nitrogen inlet of the first heat exchanger (HX1).

10. The system according to claim 9, characterized in that, The system also includes an auxiliary heat exchange unit, which includes a first compressor (C2), a first circulating hydrogen cooler (H2), a second compressor (C1), a second circulating hydrogen cooler (H3), and a cryogenic expander unit; The cryogenic unit includes multiple cryogenic heat exchangers arranged in series, and the liquefaction unit includes multiple liquefaction heat exchangers arranged in series. The outlet of the first compressor (C2) is connected to the inlet of the first circulating hydrogen cooler (H2); the outlet of the first circulating hydrogen cooler (H2) is connected to the circulating hydrogen inlet of the first heat exchanger (HX1); the circulating hydrogen outlet of the first heat exchanger (HX1) is connected to the circulating hydrogen inlet of the second heat exchanger (HX2); the circulating hydrogen outlet of the second heat exchanger (HX2) is connected to the circulating hydrogen inlet of the cryogenic unit; the circulating hydrogen outlet of the cryogenic unit is connected to the circulating hydrogen inlet of the liquefaction unit; the circulating hydrogen outlet of the liquefaction unit is connected to the first auxiliary heat exchange hydrogen inlet of the liquefaction unit; the first auxiliary heat exchange hydrogen inlet of the liquefaction unit... The outlet is connected to the first auxiliary heat exchange hydrogen inlet of the cryogenic unit; the first auxiliary heat exchange hydrogen outlet of the cryogenic unit is connected to the first auxiliary heat exchange hydrogen inlet of the second heat exchanger (HX2); the first auxiliary heat exchange hydrogen outlet of the second heat exchanger (HX2) is connected to the first auxiliary heat exchange hydrogen inlet of the first heat exchanger (HX1); the first auxiliary heat exchange hydrogen outlet of the first heat exchanger (HX1) is connected to the inlet of the second compressor (C1); the outlet of the second compressor (C1) is connected to the inlet of the second circulating hydrogen cooler (H3); the outlet of the second circulating hydrogen cooler (H3) is connected to the inlet of the first compressor (C2); The first-stage cryogenic heat exchanger of the cryogenic unit has a recooling circulating hydrogen outlet on its circulating hydrogen outlet line, which is connected to the inlet of the cryogenic expander unit. The outlet of the cryogenic expander unit is connected to the second auxiliary heat exchange hydrogen inlet of the cryogenic unit, and the second auxiliary heat exchange hydrogen outlet of the cryogenic unit is connected to the second auxiliary heat exchange hydrogen inlet of the second heat exchanger (HX2). The second auxiliary heat exchange hydrogen outlet of the second heat exchanger (HX2) is connected to the second auxiliary heat exchange hydrogen inlet of the first heat exchanger (HX1). The second auxiliary heat exchange hydrogen outlet of the first heat exchanger (HX1) is connected to the inlet of the first compressor (C2).

Images