Hydrogen liquefaction system and hydrogen liquefaction method
By introducing LNG pre-cooling units and deep-cooling units into the hydrogen liquefaction system, the pre-cooling is simplified, the hydrogen liquefaction process is improved, the utilization rate of cold energy is reduced, and the problem of high energy consumption in the existing technology is solved.
Patent Information
- Application Number
- CN202311844908.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2023-12-29
- Publication Date
- 2025-07-01
- Estimated Expiration
- Not applicable · inactive patent
AI Technical Summary
The existing hydrogen liquefaction technology has the problems of high energy consumption and low cooling energy utilization, especially in the pre-cooling part of hydrogen, which is complex and has a large energy consumption.
The LNG pre-cooling unit is used to replace the complex pre-cooling part, combine the deep cooling unit and the pressure regulating unit, and pre-cooling is used to use LNG cooling energy, and deep cooling is carried out by mixing refrigerant to form a simple hydrogen liquefaction process.
It improves the utilization rate of cold energy, reduces energy consumption, and achieves an efficient hydrogen liquefaction process.
Smart Images
Figure CN120232239A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of hydrogen liquefaction, and particularly to a hydrogen liquefaction system and a hydrogen liquefaction method. Background Art
[0002] As a secondary energy source with wide sources, clean, low-carbon characteristics, hydrogen energy plays an important role in the global energy transformation and has broad application prospects. Due to the low density of hydrogen, large-scale storage and transportation of hydrogen are currently a major problem faced by the development of hydrogen. And liquid hydrogen has become an important method to solve the large-scale storage and transportation of hydrogen due to its high energy density and high transportation efficiency.
[0003] The core of hydrogen liquefaction technology is the liquefaction part of hydrogen. Hydrogen has a low critical temperature and conversion temperature, and a small latent heat of vaporization. Its theoretical minimum liquefaction work is the highest among all gases. Since the liquefaction temperature of hydrogen is very low, only by pre-cooling hydrogen to a certain temperature or below and then throttling and expanding can a cooling effect be generated. Therefore, the cooling effect of cooling hydrogen is crucial. Summary of the Invention
[0004] The present invention aims to provide a hydrogen liquefaction system and a hydrogen liquefaction method. The present invention retains the cryogenic cycle part of the mixed refrigerant liquefaction process, and at the same time replaces the complex pre-cooling part with LNG cold energy pre-cooling, obtaining a hydrogen liquefaction process with a simpler structure, improving the cold energy utilization rate, and reducing energy consumption.
[0005] The technical solution adopted by the present invention is as follows: A hydrogen liquefaction system, the hydrogen liquefaction system comprising: An LNG pre-cooling unit, the LNG pre-cooling unit being used to pre-cool raw hydrogen through LNG and reduce the temperature of the raw hydrogen to -195°C, with the para-hydrogen concentration reaching more than 40%; A cryogenic unit, the cryogenic unit being used to cryogenically cool raw hydrogen through a mixed refrigerant and further reduce the temperature of the raw hydrogen to -252°C, with the para-hydrogen concentration reaching more than 95%, and liquefying to form liquid hydrogen; A pressure regulating unit, the pressure regulating unit being used to regulate the pressure of the liquid hydrogen to atmospheric pressure; A storage unit, the storage unit being used to temporarily store liquid hydrogen.
[0006] Further, the LNG pre-cooling unit includes a compressor Com-1, a post-cooler Cooler-1, a compressor Com-2, a post-cooler Cooler-2, a heat exchanger HX-1, and an expander Exp-1 connected in sequence; the heat exchanger HX-1 uses LNG as a pre-cooling refrigerant.
[0007] Further, the content of methane in LNG exceeds 95%.
[0008] Further, the cryogenic unit includes a normal-to-para hydrogen converter Con-1, a heat exchanger HX-2, a normal-to-para hydrogen converter Con-2, a heat exchanger HX-3, a normal-to-para hydrogen converter Con-3, and a heat exchanger HX-4 that are connected in sequence; the cryogenic unit further includes a mixer MIX-1, a compressor Com-3, a post-cooler Cooler-3, a compressor Com-4, a post-cooler Cooler-4, a compressor Com-5, a post-cooler Cooler-5, a compressor Com-6, a post-cooler Cooler-6, and a diverter TEE-1 that are connected in sequence; the mixed refrigerant flowing out of the diverter TEE-1 is divided into three paths and enters the heat exchangers HX-5, HX-6, and HX-7 respectively to exchange heat with the mixed refrigerant flowing back by itself; the heat exchanger HX-5 is connected to the expander Exp-2, the heat exchanger HX-2, and the heat exchanger HX-5 itself in sequence; the heat exchanger HX-6 is connected to the expander Exp-3, the heat exchanger HX-3, and the heat exchanger HX-6 itself in sequence; the heat exchanger HX-7 is connected to the expander Exp-4, the heat exchanger HX-4, and the heat exchanger HX-7 itself in sequence; the heat exchangers HX-5, HX-6, and HX-7 are also connected to the mixer MIX-1; the mixed refrigerant circulates in the cryogenic unit and provides cooling capacity for the heat exchangers HX-2, HX-3, and HX-4.
[0009] Further, the mixed refrigerant includes at least two of methane, ethane, propane, butane, nitrogen, and hydrogen.
[0010] Further, the pressure regulating unit includes an expander Exp-5.
[0011] Further, the storage unit includes a storage tank Tank.
[0012] Based on the same inventive concept, the present invention also provides a hydrogen liquefaction method, which is implemented based on the foregoing hydrogen liquefaction system. The hydrogen liquefaction method includes the following steps: Step S1, introducing raw hydrogen into the LNG pre-cooling unit, and pre-cooling the raw hydrogen through LNG via the LNG pre-cooling unit, and reducing the temperature of the raw hydrogen to -195°C, and the para-hydrogen concentration reaches more than 40%; Step S2, introducing the raw hydrogen obtained in Step S1 into the cryogenic unit, and deeply cooling the raw hydrogen through the mixed refrigerant via the cryogenic unit, and further reducing the temperature of the raw hydrogen to -252°C, and the para-hydrogen concentration reaches more than 95%, and liquefying to form liquid hydrogen; Step S3, introducing the liquid hydrogen obtained in Step S2 into the pressure regulating unit, and regulating the pressure of the liquid hydrogen to atmospheric pressure via the pressure regulating unit; Step S4: Introduce the liquid hydrogen obtained in step S3 into the storage unit and temporarily store it in the storage unit.
[0013] Further, in step S1, the raw hydrogen first undergoes multi-stage compression and is cooled down to -140°C, and then exchanges heat with LNG to be cooled down to -195°C.
[0014] The beneficial effects of the present invention are as follows: 1. The present invention provides a hydrogen liquefaction system, which consists of an LNG precooling unit, a cryogenic unit, a pressure regulating unit, a storage unit, etc. By adding an LNG precooling unit, the cold energy of LNG is fully utilized, the cold energy utilization rate is improved, the structure is simpler, and the energy consumption is reduced.
[0015] 2. The present invention also provides a hydrogen liquefaction method, which retains the cryogenic cycle part of the mixed refrigerant liquefaction process, that is, the cryogenic part is still a mixed refrigerant cycle, and at the same time replaces the complex precooling part with LNG cold energy precooling to obtain a simpler hydrogen liquefaction process and improve the cold energy utilization rate. Description of the Drawings
[0016] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.
[0017] Figure 1 It is the process flow diagram of the hydrogen liquefaction system in Embodiment 1; in the figure, H represents hydrogen, CR represents mixed refrigerant, LH represents liquid hydrogen, LNG represents liquefied natural gas, and NG represents natural gas. Detailed Embodiments
[0018] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention.
[0019] The following disclosure provides many different embodiments or examples for implementing different structures of the present invention. To simplify the disclosure of the present invention, components and settings of specific examples are described below. Of course, they are only examples and are not intended to limit the present invention.
[0020] The embodiments of the invention will be described in detail below with reference to the accompanying drawings.
[0021] Embodiment 1, such as Figure 1 a hydrogen liquefaction system shown in. The hydrogen liquefaction system includes an LNG precooling unit, a cryogenic unit, a pressure regulating unit, and a storage unit. Among them, the LNG precooling unit is used to precool the raw hydrogen by LNG and reduce the temperature of the raw hydrogen to -195°C, with the para-hydrogen concentration reaching more than 40%. The cryogenic unit is used to deeply cool the raw hydrogen by a mixed refrigerant and further reduce the temperature of the raw hydrogen to -252°C, with the para-hydrogen concentration reaching more than 95%, and liquefy it to form liquid hydrogen. The pressure regulating unit is used to regulate the pressure of the liquid hydrogen to atmospheric pressure. The storage unit is used to temporarily store the liquid hydrogen.
[0022] Specifically, the LNG precooling unit includes a compressor Com-1, an aftercooler Cooler-1, a compressor Com-2, an aftercooler Cooler-2, a heat exchanger HX-1, and an expander Exp-1 connected in sequence; the heat exchanger HX-1 uses LNG as a precooling refrigerant, and the methane content in the LNG exceeds 95%. The raw hydrogen is introduced into the LNG precooling unit and precooled by the LNG through the LNG precooling unit, and the temperature of the raw hydrogen is reduced to -195°C, with the para-hydrogen concentration reaching more than 40% The cryogenic unit includes a normal-para hydrogen converter Con-1, a heat exchanger HX-2, a normal-para hydrogen converter Con-2, a heat exchanger HX-3, a normal-para hydrogen converter Con-3, and a heat exchanger HX-4 connected in sequence; the cryogenic unit further includes a mixer MIX-1, a compressor Com-3, a post-cooler Cooler-3, a compressor Com-4, a post-cooler Cooler-4, a compressor Com-5, a post-cooler Cooler-5, a compressor Com-6, a post-cooler Cooler-6, and a diverter TEE-1 connected in sequence; the mixed refrigerant flowing out of the diverter TEE-1 is divided into three paths and enters a heat exchanger HX-5, a heat exchanger HX-6, and a heat exchanger HX-7 respectively to exchange heat with the mixed refrigerant flowing back by itself; the heat exchanger HX-5 is connected to an expander Exp-2, a heat exchanger HX-2, and the heat exchanger HX-5 itself in sequence; the heat exchanger HX-6 is connected to an expander Exp-3, a heat exchanger HX-3, and the heat exchanger HX-6 itself in sequence; the heat exchanger HX-7 is connected to an expander Exp-4, a heat exchanger HX-4, and the heat exchanger HX-7 itself in sequence; the heat exchanger HX-5, the heat exchanger HX-6, and the heat exchanger HX-7 are also connected to the mixer MIX-1; the mixed refrigerant circulates in the cryogenic unit and provides cooling capacity for the heat exchanger HX-2, the heat exchanger HX-3, and the heat exchanger HX-4. The mixed refrigerant includes at least two of methane, ethane, propane, butane, nitrogen, and hydrogen.
[0023] The raw hydrogen cooled to -195°C is introduced into the cryogenic unit, and the raw hydrogen is cryogenically cooled by the mixed refrigerant via the cryogenic unit, and the temperature of the raw hydrogen is further reduced to -252°C, and the concentration of para-hydrogen reaches more than 95%, and it is liquefied to form liquid hydrogen. The pressure regulating unit includes an expander Exp-5. The liquid hydrogen at -252°C is introduced into the pressure regulating unit, and the pressure of the liquid hydrogen is regulated to atmospheric pressure via the pressure regulating unit.
[0024] The storage unit includes a storage tank Tank. The liquid hydrogen at atmospheric pressure is introduced into the storage unit and temporarily stored by the storage unit.
[0025] In this embodiment, a hydrogen liquefaction system is provided, which is composed of an LNG precooling unit, a cryogenic unit, a pressure regulating unit, a storage unit, etc. By adding an LNG precooling unit, the cold energy of LNG is fully utilized, the cold energy utilization rate is improved, the structure is simpler, and the energy consumption is reduced.
[0026] Example 2. In this example, a hydrogen liquefaction method is provided, which is implemented based on the hydrogen liquefaction system described in Example 1. The hydrogen liquefaction system includes an LNG precooling unit, a cryogenic unit, a pressure regulating unit, and a storage unit. The LNG precooling unit is used to precool the feed hydrogen with LNG and reduce the temperature of the feed hydrogen to -195°C, with the para-hydrogen concentration reaching over 40%. The cryogenic unit is used to cryogenically cool the feed hydrogen with a mixed refrigerant and further reduce the temperature of the feed hydrogen to -252°C, with the para-hydrogen concentration reaching over 95%, and liquefy it to form liquid hydrogen. The pressure regulating unit is used to adjust the pressure of the liquid hydrogen to atmospheric pressure. The storage unit is used to temporarily store the liquid hydrogen.
[0027] The hydrogen liquefaction method includes the following steps: Step S1: Introduce the feed hydrogen into the LNG precooling unit, and precool the feed hydrogen with LNG through the LNG precooling unit, and reduce the temperature of the feed hydrogen to -195°C, with the para-hydrogen concentration reaching over 40%; Step S2: Introduce the feed hydrogen obtained in Step S1 into the cryogenic unit, and cryogenically cool the feed hydrogen with a mixed refrigerant through the cryogenic unit, and further reduce the temperature of the feed hydrogen to -252°C, with the para-hydrogen concentration reaching over 95%, and liquefy it to form liquid hydrogen; Step S3: Introduce the liquid hydrogen obtained in Step S2 into the pressure regulating unit, and adjust the pressure of the liquid hydrogen to atmospheric pressure through the pressure regulating unit; Step S4: Introduce the liquid hydrogen obtained in Step S3 into the storage unit, and temporarily store it in the storage unit.
[0028] Among them, in Step S1, the feed hydrogen is first multi-stage compressed and cooled to -140°C, and then heat-exchanged with LNG to be cooled to -195°C.
[0029] A hydrogen liquefaction method provided in this example retains the cryogenic cycle part of the mixed refrigerant liquefaction process, that is, the cryogenic part is still a mixed refrigerant cycle, and at the same time replaces the complex precooling part with LNG cold energy precooling, obtaining a simpler hydrogen liquefaction process and improving the cold energy utilization rate.
Claims
1. A hydrogen liquefaction system, characterized in that, The hydrogen liquefaction system includes: An LNG precooling unit, which is used to precool the feed hydrogen by LNG and reduce the temperature of the feed hydrogen to -195°C, with the para-hydrogen concentration reaching over 40%; A cryogenic unit, which is used to cryogenically cool the feed hydrogen by a mixed refrigerant and further reduce the temperature of the feed hydrogen to -252°C, with the para-hydrogen concentration reaching over 95%, and liquefy it to form liquid hydrogen; A pressure regulating unit, which is used to regulate the pressure of the liquid hydrogen to atmospheric pressure; A storage unit, which is used to temporarily store the liquid hydrogen.
2. The hydrogen liquefaction system according to claim 1, wherein The LNG precooling unit includes a compressor Com-1, an aftercooler Cooler-1, a compressor Com-2, an aftercooler Cooler-2, a heat exchanger HX-1, and an expander Exp-1 connected in sequence; the heat exchanger HX-1 uses LNG as the precooling refrigerant.
3. The hydrogen liquefaction system according to claim 2, wherein In the composition of the precooling refrigerant, the methane content in the LNG exceeds 95%.
4. The hydrogen liquefaction system according to claim 1, wherein, The cryogenic unit includes an ortho-para hydrogen converter Con-1, a heat exchanger HX-2, an ortho-para hydrogen converter Con-2, a heat exchanger HX-3, an ortho-para hydrogen converter Con-3, and a heat exchanger HX-4 connected in sequence; the cryogenic unit also includes a mixer MIX-1, a compressor Com-3, an aftercooler Cooler-3, a compressor Com-4, an aftercooler Cooler-4, a compressor Com-5, an aftercooler Cooler-5, a compressor Com-6, an aftercooler Cooler-6, and a diverter TEE-1 connected in sequence; the mixed refrigerant flowing out of the diverter TEE-1 is divided into three paths and enters the heat exchangers HX-5, HX-6, and HX-7 respectively to exchange heat with the mixed refrigerant flowing back by itself; the heat exchanger HX-5 is connected to the expander Exp-2, the heat exchanger HX-2, and the heat exchanger HX-5 itself in sequence; the heat exchanger HX-6 is connected to the expander Exp-3, the heat exchanger HX-3, and the heat exchanger HX-6 itself in sequence; the heat exchanger HX-7 is connected to the expander Exp-4, the heat exchanger HX-4, and the heat exchanger HX-7 itself in sequence; the heat exchangers HX-5, HX-6, and HX-7 are also connected to the mixer MIX-1; the mixed refrigerant circulates in the cryogenic unit and provides cooling capacity for the heat exchangers HX-2, HX-3, and HX-4.
5. The hydrogen liquefaction system according to claim 1 or 4, characterized in that, The mixed refrigerant includes at least two of methane, ethane, propane, butane, nitrogen, and hydrogen.
6. The hydrogen liquefaction system according to claim 1, wherein The pressure regulating unit includes an expander Exp-5.
7. The hydrogen liquefaction system according to claim 1, wherein The storage unit includes a storage tank Tank.
8. A hydrogen liquefaction method, which is implemented based on the hydrogen liquefaction system described in any one of claims 1 to 7, characterized in that, The hydrogen liquefaction method includes the following steps: Step S1, introducing the feed hydrogen into the LNG precooling unit, and precooling the feed hydrogen by LNG via the LNG precooling unit and reducing the temperature of the feed hydrogen to -195°C, with the para-hydrogen concentration reaching over 40%; Step S2: Introduce the raw hydrogen obtained in step S1 into the cryogenic unit, and cryogenically cool the raw hydrogen through a mixed refrigerant via the cryogenic unit, further reducing the temperature of the raw hydrogen to -252°C, with the para-hydrogen concentration reaching over 95%, and then liquefy it to form liquid hydrogen. Step S3: Introduce the liquid hydrogen obtained in step S2 into the pressure regulating unit, and regulate the pressure of the liquid hydrogen to atmospheric pressure via the pressure regulating unit. Step S4: Introduce the liquid hydrogen obtained in step S3 into the storage unit, and temporarily store it in the storage unit.
9. The hydrogen liquefaction method according to claim 8, wherein In step S1, the raw hydrogen is first multi-stage compressed and cooled to -140°C, and then heat-exchanged with LNG to be cooled to -195°C.