Hydrogen liquefaction system and raw material hydrogen purification device for hydrogen liquefaction system

Abstract

The invention provides a hydrogen liquefaction system and a raw material hydrogen purification device used for the hydrogen liquefaction system. The raw material hydrogen purification device comprises a first-stage precooling unit, a second-stage precooling unit and a low-temperature adsorption unit; raw material hydrogen is pre-cooled to a first temperature interval through the first-stage pre-cooling unit, then enters the second-stage pre-cooling unit, is pre-cooled to a second temperature interval in the second-stage pre-cooling unit, then enters the low-temperature adsorption unit, and is subjected to impurity removal to become low-temperature purified hydrogen; and the low-temperature purified hydrogen returns to the first-stage precooling unit to provide cooling capacity for the raw material hydrogen and then is connected into a cold box of the hydrogen liquefaction system to be liquefied. Impurities in the raw material hydrogen are subjected to low-temperature separation through the first-stage precooling process and the second-stage precooling process, the separated impurities are subjected to adsorption and impurity removal through the low-temperature adsorption process, the purification rate is effectively improved, the purified low-temperature hydrogen is used for providing cooling capacity for the first-stage precooling process of the raw material hydrogen, and the energy efficiency of the system is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of hydrogen liquefaction, in particular to a hydrogen liquefaction system and a raw hydrogen purification device used therefor. Background Art

[0002] In the hydrogen liquefaction system, the raw hydrogen often contains gaseous impurities such as water vapor, carbon dioxide, and nitrogen oxides, as well as inert gases such as nitrogen and oxygen and solid particulate impurities such as metal oxide dust. These impurities can cause multiple hazards during the liquefaction process. For example, water vapor forms ice crystals in the low-temperature section, causing blockage of the flow channels of the main and secondary pre-cooling units in the cold box (pressure loss increases by 30-50%), frost and stagnation of the expansion valve, and increased liquefaction energy consumption due to increased thermal resistance; acidic impurities react with metal surfaces under high pressure and low temperature conditions, causing carbonic acid corrosion or nitrate crystallization corrosion, resulting in a shortened life of key equipment; at the same time, residual impurities will reduce the purity of liquid hydrogen and even threaten the safety of downstream applications. Therefore, purification of raw hydrogen is an essential and key link in the hydrogen liquefaction process.

[0003] The current mainstream purification technology system faces "three difficulties" bottlenecks: first, the specific surface area and pore size distribution of the adsorption material are difficult to coordinate, resulting in a contradiction between purification depth and selectivity; second, the traditional process greatly reduces the energy efficiency of the system, and energy consumption and efficiency cannot be balanced; third, the coordinated treatment of multiple impurities requires multiple devices in series, resulting in superposition of pressure loss and a sharp increase in operational complexity. These problems have seriously restricted the economy and reliability of the hydrogen liquefaction system. It is urgent to develop a liquefied hydrogen purification solution that combines efficient mass transfer, low energy consumption, and corrosion resistance, focusing on breakthroughs in key technologies such as low-temperature adsorption optimization and multi-stage coordinated capture of impurities to meet the needs of industrial-grade liquid hydrogen purity (>99.99%) and long-term stable operation.

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

[0005] The technical problem to be solved by the present invention is to at least overcome some of the shortcomings of the prior art and provide a raw hydrogen purification device for a hydrogen liquefaction system. Impurities in the raw hydrogen are separated at low temperature through the first-stage precooling and second-stage precooling processes, and the separated impurities are adsorbed and removed by a low-temperature adsorption process, thereby effectively improving the purification rate. The purified low-temperature hydrogen is used to provide cooling capacity for the first-stage precooling process of the raw hydrogen, thereby improving the energy efficiency of the system.

[0006] In order to solve the above technical problems, the basic concept of the technical solution adopted by the present invention is:

[0007] A raw hydrogen purification device for a hydrogen liquefaction system, comprising a primary precooling unit, a secondary precooling unit and a cryogenic adsorption unit;

[0008] The raw hydrogen is precooled to a first temperature range in the first precooling unit and then enters the second precooling unit. After being precooled to a second temperature range in the second precooling unit, it enters the low-temperature adsorption unit for impurity removal and becomes low-temperature purified hydrogen.

[0009] The low-temperature purified hydrogen returns to the primary precooling unit to provide cooling for the raw hydrogen and is then connected to the cold box of the hydrogen liquefaction system for liquefaction.

[0010] In some embodiments, the secondary precooling unit includes a first heat exchange channel and a second heat exchange channel for heat exchange, one end of the first heat exchange channel is connected to the primary precooling unit, and the other end is connected to one end of the low-temperature adsorption unit, and the other end of the low-temperature adsorption unit is connected to the primary precooling unit;

[0011] Both ends of the second heat exchange channel are respectively connected to an external cold source, so that a refrigerant is supplied into the second heat exchange channel to cool the raw hydrogen gas to the second temperature range for low-temperature separation;

[0012] The raw hydrogen after low-temperature separation is subjected to low-temperature adsorption by the low-temperature adsorption unit and then returns to the primary precooling unit.

[0013] In some embodiments, a one-way valve is provided on the connecting pipeline between the first heat exchange channel and the low-temperature adsorption unit, and the one-way valve allows the raw hydrogen after low-temperature separation to flow to the low-temperature adsorption unit in one direction.

[0014] In some embodiments, the raw hydrogen purification device further comprises an ultra-low temperature hydrogen introduction pipeline, wherein the ultra-low temperature hydrogen introduction pipeline is connected to the primary precooling unit;

[0015] Wherein, a first temperature detection unit is provided on the connecting pipeline between the first heat exchange channel and the primary precooling unit, and / or a second temperature detection unit is provided on the connecting pipeline between the low-temperature adsorption unit and the primary precooling unit;

[0016] When the temperature of the raw hydrogen detected by the first temperature detection unit exceeds the upper limit of the first temperature range, and / or the temperature of the low-temperature purified hydrogen detected by the second temperature detection unit exceeds the upper limit of the second temperature range, the ultra-low temperature hydrogen introduction pipeline is connected to introduce ultra-low temperature hydrogen into the first-level precooling unit to provide auxiliary cooling for the raw hydrogen.

[0017] In some embodiments, the ultra-low temperature hydrogen introduction pipeline is configured to be connected to a cold box of the hydrogen liquefaction system.

[0018] In some embodiments, the cryogenic adsorption unit is a regenerable adsorption unit;

[0019] Wherein, the raw hydrogen purification device further comprises an activation gas introduction pipeline and a venting pipeline, and the activation gas introduction pipeline and the venting pipeline are respectively connected to the low-temperature adsorption unit;

[0020] A hydrogen concentration detection unit is connected to the low-temperature purified hydrogen output pipeline of the first-stage precooling unit. When the hydrogen concentration detected by the hydrogen concentration detection unit is lower than a preset first concentration threshold, the external supply is cut off, and the activation gas introduction pipeline and the venting pipeline are connected to regenerate the low-temperature adsorption unit.

[0021] In some embodiments, the process of regenerating the low-temperature adsorption unit includes rewarming, activation gas replacement, activation gas desorption and hydrogen replacement.

[0022] In some embodiments, the first temperature range is -50°C to -100°C; the second temperature range is -150°C to -200°C.

[0023] In some embodiments, the primary precooling unit adopts a plate heat exchange structure, and the secondary precooling unit adopts a tube heat exchange structure.

[0024] The present invention also provides a hydrogen liquefaction system, comprising the raw hydrogen purification device for the hydrogen liquefaction system described above.

[0025] After adopting the above technical scheme, the present invention has the following beneficial effects compared with the prior art.

[0026] (1) The raw hydrogen purification device for a hydrogen liquefaction system provided by the present invention separates impurities in the raw hydrogen at low temperature through the primary precooling and secondary precooling processes, and then uses a low-temperature adsorption process to adsorb and remove the separated impurities, thereby effectively removing impurities and effectively improving the purification rate. In addition, the purified low-temperature hydrogen is used to provide cooling capacity for the primary precooling process of the raw hydrogen, thereby improving the energy efficiency of the system.

[0027] (2) The raw hydrogen purification device for the hydrogen liquefaction system provided by the present invention can supplement the cooling capacity when the cooling capacity of the purified low-temperature hydrogen is insufficient by introducing ultra-low-temperature hydrogen into the primary pre-cooling unit, thereby ensuring the pre-cooling effect of the raw hydrogen. In addition, by drawing out a portion of ultra-low-temperature hydrogen from the cold box of the hydrogen liquefaction system to supplement the cooling capacity of the raw hydrogen, the initial temperature of the gas to be liquefied in the cold box can be lowered, the energy consumption required for subsequent liquefaction can be reduced, and the overall energy efficiency of the system can be improved by recycling the cooling capacity. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The accompanying drawings are part of the present invention and are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention, but do not constitute an improper limitation of the present invention. Obviously, the drawings described below are only some embodiments. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work. In the accompanying drawings:

[0029] Figure 1 is a schematic diagram of a raw hydrogen purification device for a hydrogen liquefaction system according to an exemplary embodiment of the present invention;

[0030] Figures 2 to 5 They are respectively schematic flow diagrams of different operating conditions of a raw hydrogen purification device for a hydrogen liquefaction system provided according to exemplary embodiments of the present invention.

[0031] In the figure: 100, raw hydrogen purification device; 101, primary precooling unit; 102, secondary precooling unit; 103, low-temperature adsorption unit; 104, one-way valve; 105, ultra-low-temperature hydrogen introduction pipeline; 106, first temperature detection unit; 107, second temperature detection unit; 108, activated gas introduction pipeline; 109, venting pipeline; 110, safety valve; 111, vacuum pipeline; 112, reflux pipeline; 113, pressure detection unit.

[0032] It should be noted that these drawings and textual descriptions are not intended to limit the conceptual scope of the present invention in any way, but are intended to illustrate the concept of the present invention for those skilled in the art by referring to specific embodiments. DETAILED DESCRIPTION

[0033] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. The following embodiments are used to illustrate the present invention but are not used to limit the scope of the present invention.

[0034] In the description of the present invention, it should be noted that the terms "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "inside" and "outside" etc. indicating directions or positional relationships are based on the directions or positional relationships shown in the accompanying drawings, and are 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 direction, be constructed and operated in a specific direction, and therefore cannot be understood as a limitation on the present invention.

[0035] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected" and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0036] Figure 1 A schematic diagram of a hydrogen liquefaction system and a raw hydrogen purification device 100 used in the hydrogen liquefaction system according to an exemplary embodiment of the present invention is shown. Figures 2 to 5 1 and 2 respectively show the flow diagrams of different working conditions of the raw hydrogen purification device 100 for the hydrogen liquefaction system provided according to an exemplary embodiment of the present invention. It should be noted that Figures 2 to 5 The pipelines not related to this working condition are omitted.

[0037] like Figure 1 As shown, the raw hydrogen purification device 100 includes a primary precooling unit 101, a secondary precooling unit 102 and a low-temperature adsorption unit 103; the raw hydrogen is precooled to a first temperature range by the primary precooling unit 101 and then enters the secondary precooling unit 102, and then is precooled to a second temperature range in the secondary precooling unit 102 and then enters the low-temperature adsorption unit 103 for impurity removal to become low-temperature purified hydrogen; the low-temperature purified hydrogen returns to the primary precooling unit 101 to provide cooling for the raw hydrogen and then is connected to the cold box of the hydrogen liquefaction system for liquefaction.

[0038] It should be explained here that as the temperature of the raw hydrogen decreases, the activity of the impurities carried therein will be significantly reduced. This is because the low temperature environment slows down the movement of the impurity molecules, and their chemical activity is also weakened, making it easier for the impurities to be separated from the hydrogen. Based on this, the present invention sets a two-stage precooling unit to perform low-temperature separation of impurity gases with different boiling points, and adsorbs the separated impurities through the low-temperature adsorption unit 103, which can significantly improve the purification rate of the raw hydrogen.

[0039] Specifically, refer to Figure 2 As shown, the raw hydrogen first enters the primary pre-cooling unit 101, and undergoes preliminary heat exchange with the cooled and purified low-temperature purified hydrogen, so that the temperature of the raw hydrogen is reduced to between -50°C and -100°C. Within this temperature range, the boiling points of impurity gases such as water vapor and carbon dioxide carried in the raw hydrogen are higher than the boiling point of hydrogen, and they will be liquefied or solidified first, thereby being separated from the hydrogen.

[0040] The separated impurities will flow with the gas into the secondary precooling unit 102 for secondary precooling to between -150°C and -200°C. Within this temperature range, the boiling points of inert gas impurities such as oxygen, nitrogen, argon, etc. carried in the raw hydrogen are also higher than the boiling point of hydrogen, and will also be preferentially liquefied or solidified, thereby being separated from the hydrogen.

[0041] The separated impurities will continue to flow with the gas into the low-temperature adsorption unit 103. The activated carbon, molecular sieve and other adsorbents set in the low-temperature adsorption unit 103 have a strong adsorption capacity for the separated impurities under low-temperature conditions. In the low-temperature adsorption unit 103, the adsorbent firmly adsorbs the impurities carried in the raw hydrogen (such as liquefied or solidified water vapor, carbon dioxide, oxygen, nitrogen, argon, carbon monoxide, hydrocarbon compounds and trace amounts of sulfides, etc.) on the surface or pores through the dual effects of physical adsorption and chemical adsorption, ensuring that the impurity gas can be fully adsorbed, thereby achieving effective removal of impurities, reducing the content of impurities in the gas, effectively reducing the potential damage of impurities to the equipment during the subsequent hydrogen liquefaction process, extending the service life of the equipment, and improving the operating efficiency and safety of the entire hydrogen liquefaction system.

[0042] It should be pointed out here that in order to ensure the adsorption effect of the adsorbent on impurities, it should be ensured that the residence time of the raw hydrogen in the low-temperature adsorption unit 103 meets the corresponding conditions. For example, the raw hydrogen will stay in the low-temperature adsorption unit 103 for 10 minutes to 30 minutes to ensure the contact time between the impurity gas and the adsorbent, and ensure that the impurity gas can be fully adsorbed by the adsorbent, thereby achieving efficient removal of impurities.

[0043] As an example, a multi-stage expansion refrigeration unit and a throttling unit are provided in the cold box in the hydrogen liquefaction system, which can reduce the temperature of the low-temperature purified hydrogen to below -253°C and realize the phase change conversion of hydrogen to liquid.

[0044] In some embodiments, the secondary precooling unit 102 includes a first heat exchange channel and a second heat exchange channel with heat exchange, one end of the first heat exchange channel is connected to the primary precooling unit 101, and the other end is connected to one end of the low-temperature adsorption unit 103, and the other end of the low-temperature adsorption unit 103 is connected to the primary precooling unit 101; the two ends of the second heat exchange channel are respectively connected to an external cold source to supply refrigerant into the second heat exchange channel to cool the raw hydrogen to the second temperature range for low-temperature separation; the raw hydrogen after low-temperature separation is returned to the primary precooling unit 101 after low-temperature adsorption via the low-temperature adsorption unit 103.

[0045] As an example, the external cold source may be a liquid nitrogen source, that is, liquid nitrogen is used as a refrigerant, and the cold capacity of the liquid nitrogen is used to deeply pre-cool the raw hydrogen.

[0046] In some embodiments, the low temperature adsorption unit 103 is a regenerable adsorption unit. Based on this, the raw hydrogen purification device 100 further includes an activation gas introduction pipeline 108 and a venting pipeline 109. Figure 1 As shown, the activation gas introduction pipeline 108 and the venting pipeline 109 are respectively connected to the low-temperature adsorption unit 103; the low-temperature purified hydrogen output pipeline of the first-level precooling unit 101 is connected with a hydrogen concentration detection unit. When the hydrogen concentration detected by the hydrogen concentration detection unit is lower than the preset first concentration threshold, the external supply is cut off, and the activation gas introduction pipeline 108 and the venting pipeline 109 are connected to regenerate the low-temperature adsorption unit 103 so that the adsorbent regains the adsorption capacity. The low-temperature adsorption unit 103 can be put into use again to continue the next round of impurity removal operation.

[0047] The above-mentioned process of regenerating the low-temperature adsorption unit 103 includes rewarming, activation gas replacement, activation gas desorption and hydrogen replacement.

[0048] Specifically, a sampling line is led out from the connecting line between the primary precooling unit 101 and the cold box, and the sampling line is connected to a hydrogen concentration detection unit such as a gas analyzer, for real-time monitoring of the purity of the purified hydrogen. When the analysis result shows that the hydrogen concentration is lower than the preset concentration threshold, that is, the impurity content in the hydrogen does not meet the standard, it means that the adsorbent in the low-temperature adsorption unit 103 has reached saturation, and the low-temperature adsorption unit 103 needs to be regenerated.

[0049] Refer to the following Figure 3 The specific operation steps of the regeneration process are described as follows:

[0050] The first step is rewarming: close the valves at the raw hydrogen inlet and the low-temperature purified hydrogen outlet of the first-level precooling unit 101, stop the supply of raw hydrogen, close the valve between the second-level precooling unit 102 and the external cold source, stop the supply of refrigerant, so as to cut off the connection between the raw hydrogen purification device 100 and the external raw hydrogen and low-temperature medium, so that the temperature of each component and pipeline of the raw hydrogen purification device 100 gradually rises to room temperature.

[0051] The second step is activated gas replacement: the activated gas (such as nitrogen and inert gas, etc., nitrogen is used as an example below) is introduced into the low-temperature adsorption unit 103 through the activated gas introduction pipeline 108 to a first preset pressure (such as 0.5MPa) and maintained for a preset time, and then discharged to a second preset pressure (such as 0.1MPa) through the venting pipeline 109 to complete a pressure release. This is repeated several times to reduce the hydrogen content in the low-temperature adsorption unit 103 to below 0.001%, ensuring that there is no residual hydrogen in the low-temperature adsorption unit 103 to avoid danger during the heating process. It should be pointed out here that a one-way valve 104 is provided on the connecting pipeline between the first heat exchange channel and the low-temperature adsorption unit 103, and the one-way valve 104 allows the raw hydrogen after low-temperature separation to flow to the low-temperature adsorption unit 103 in one direction. In other words, the setting of the one-way valve 104 can prevent the activated gas from entering the secondary precooling unit 102 and the primary precooling unit 101 when the low-temperature adsorption unit 103 is replaced by the activated gas, thereby increasing the difficulty of subsequent impurity removal. In addition, in the normal impurity removal process, the setting of the one-way valve 104 also helps to maintain the pressure stability in the low-temperature adsorption unit 103 to prevent the adsorption effect from being affected by pressure fluctuations.

[0052] The third step is desorption of activated gas: after the hydrogen content in the low-temperature adsorption unit 103 reaches the standard, the temperature of the low-temperature adsorption unit 103 is gradually increased using heated nitrogen. As the temperature increases, the impurity gas on the adsorbent is gradually desorbed and discharged through the venting line 109 along with the nitrogen, thereby restoring the adsorption capacity of the adsorbent.

[0053] The fourth step is hydrogen replacement: after the temperature rise is completed, the activated gas introduction pipeline 108 is cut off, and the valve at the raw hydrogen inlet of the first-level precooling unit 101 is opened to pass raw hydrogen into the raw hydrogen purification device 100 to a first preset pressure (e.g., 0.5MPa) and then maintain a preset time, and then discharge to a second preset pressure (e.g., 0.1MPa) through the venting pipeline 109, completing a holding pressure release. Through repeated holding and releasing operations, the nitrogen in the system is replaced with hydrogen, ensuring that the purity of hydrogen in the raw hydrogen purification device 100 is up to standard, restoring its working state, and re-putting into use. It should be pointed out that in the step of hydrogen replacement, the valve at the low-temperature purified hydrogen outlet of the first-level precooling unit 101 and the valve between the second-level precooling unit 102 and the external cold source are kept in a cut-off state.

[0054] It should be pointed out that the venting pipeline 109 and the raw hydrogen gas inlet pipeline of the primary precooling unit 101 are both provided with a pressure detection unit 113 for detecting the pressure in the raw hydrogen purification device 100 so that it meets the requirements of safe production. The pressure detection unit 113 can adopt a structure commonly used in the art. In addition, a safety valve 110 is also provided on the raw hydrogen gas inlet pipeline of the primary precooling unit 101, which can automatically open when the pressure in the system exceeds the preset safety value, quickly release the pressure, prevent the equipment from being damaged by overpressure, and ensure the safety and reliability of the overall system.

[0055] After the above regeneration process, the adsorbent in the low-temperature adsorption unit 103 regains its adsorption capacity, and the low-temperature adsorption unit 103 can be put into use again to continue the next round of impurity removal operation.

[0056] In an alternative manner, a flushing and vacuuming step may be used to allow the adsorbent in the cryogenic adsorption unit 103 to regain its adsorption capacity. Figure 4 As described above, the flushing medium (such as nitrogen and inert gas) is first introduced through the activation gas introduction pipeline 108 to flush the adsorbent, and then the vacuum pump on the vacuum pipeline 111 is evacuated to further remove residual impurities. At the same time, one low-temperature adsorption unit 103 can be added, one for backup and one for use. When one low-temperature adsorption unit 103 is saturated with adsorption, it can be switched to another low-temperature adsorption unit 103 for adsorption.

[0057] It should be pointed out that the above-mentioned vacuum pipeline 111 can also be used for vacuum treatment in other processes of the raw hydrogen purification device 100, which will not be elaborated in the present invention.

[0058] Further, refer to Figure 1 and Figure 2 As shown, a reflux pipeline 112 is provided between the low-temperature purified hydrogen output pipeline of the first-stage precooling unit 101 and the connecting pipeline between the first-stage precooling unit 101 and the second-stage precooling unit 102. When the hydrogen concentration detected by the hydrogen concentration detection unit is lower than the preset second concentration threshold, the second concentration threshold is greater than the first concentration threshold, indicating that the adsorption capacity of the low-temperature adsorption unit 103 is acceptable, but the purity of the hydrogen output from the low-temperature purified hydrogen output pipeline still cannot meet the requirements, and the impurity content is still at a relatively high level. At this time, the reflux pipeline 112 is turned on, and the low-temperature purified hydrogen output from the first-stage precooling unit 101 returns to the second-stage precooling unit 102 and the low-temperature adsorption unit 103 for deep precooling and low-temperature adsorption again, so as to improve the purity of the hydrogen output from the low-temperature purified hydrogen output pipeline.

[0059] In some embodiments, the secondary precooling unit 102 adopts a tubular heat exchange structure, for example, the tubular heat exchange structure includes a shell and a heat exchange tube disposed in the shell, the channel in the heat exchange tube constitutes the above-mentioned first heat exchange channel, and the channel in the shell constitutes the above-mentioned second heat exchange channel. When the raw hydrogen passes through the heat exchange tube, heat is exchanged with the liquid nitrogen in the shell, and the temperature of the raw hydrogen is cooled to between -150°C and -200°C.

[0060] The first-stage precooling unit 101 adopts a plate heat exchange structure. For example, the plate heat exchange structure includes a frame and a plurality of heat exchange plates arranged on the frame. A flow channel is arranged in the heat exchange plate. The raw hydrogen and the low-temperature purified hydrogen exchange heat through the flow channel between the heat exchange plates, and the temperature of the raw hydrogen is cooled to between -50°C and -100°C.

[0061] In the above scheme, the raw hydrogen is precooled by a combination of a plate heat exchange structure and a tube heat exchange structure, which can effectively improve the precooling effect and ensure that the impurity gas in the raw hydrogen can be separated from the hydrogen in advance under a low temperature environment.

[0062] In some embodiments, Figure 1 As shown, the raw hydrogen purification device 100 also includes an ultra-low temperature hydrogen introduction pipeline 105, and the ultra-low temperature hydrogen introduction pipeline 105 is connected to the primary precooling unit 101; wherein, a first temperature detection unit 106 is provided on the connecting pipeline between the first heat exchange channel and the primary precooling unit 101, and / or, a second temperature detection unit 107 is provided on the connecting pipeline between the low temperature adsorption unit 103 and the primary precooling unit 101; when the temperature of the raw hydrogen detected by the first temperature detection unit 106 exceeds the upper limit of the first temperature interval, and / or, when the temperature of the low temperature purified hydrogen detected by the second temperature detection unit 107 exceeds the upper limit of the second temperature interval, the ultra-low temperature hydrogen introduction pipeline 105 is turned on to introduce ultra-low temperature hydrogen into the primary precooling unit 101 to provide auxiliary cooling capacity for the raw hydrogen, refer to Figure 5 The first temperature detection unit 106 and the second temperature detection unit 107 can adopt the commonly used structures in the art.

[0063] In the above scheme, when the temperature of the raw hydrogen detected by the first temperature detection unit 106 exceeds the upper limit of the first temperature range, and / or the temperature of the low-temperature purified hydrogen detected by the second temperature detection unit 107 exceeds the upper limit of the second temperature range, it means that if the raw hydrogen is pre-cooled only by relying on the cooling capacity of the low-temperature purified hydrogen, the temperature range in which the impurities are preferentially liquefied or solidified cannot be reached. At this time, the ultra-low temperature hydrogen introduction pipeline 105 is turned on, and ultra-low temperature hydrogen is introduced into the first-level pre-cooling unit 101 to provide auxiliary cooling capacity for the raw hydrogen, which can effectively ensure the separation effect of the impurity gas.

[0064] Furthermore, the ultra-low temperature hydrogen introduction pipeline 105 is configured to be connected to the cold box of the hydrogen liquefaction system. That is, a portion of ultra-low temperature hydrogen is drawn out from the cold box of the hydrogen liquefaction system, and heat exchange is performed with the raw hydrogen to be liquefied through the primary pre-cooling unit 101. This heat exchange process not only significantly reduces the initial temperature of the gas to be liquefied and reduces the energy consumption required for subsequent liquefaction, but also effectively improves the overall energy efficiency of the hydrogen liquefaction system by recycling the cold capacity.

[0065] It should be pointed out that in the whole impurity removal process, the above impurity removal steps are continuously circulated to ensure that the impurity content of hydrogen in the raw hydrogen purification device 100 is always at a low level, for example, the impurity content is always less than 1ppm. At the same time, by controlling the flow rate of hydrogen in the precooling unit at each level and the low-temperature adsorption unit 103, combined with the heat exchange capacity and impurity content of the device, the flow rate is stabilized in a suitable range using a regulating valve. In the raw hydrogen purification device 100, the hydrogen flow rate is controlled at 1m / s to 3m / s to ensure that impurities have enough time to condense in the precooling units at each level to avoid reducing the impurity removal effect due to excessive flow rate. In the subsequent stage, the flow rate can be appropriately reduced according to the actual situation to achieve more refined and deeper impurity removal and further improve the purity of hydrogen.

[0066] In addition, the present invention collects data in real time through the temperature detection unit, the pressure detection unit and the hydrogen concentration detection unit, and combines the intelligent algorithm of the central control system to dynamically adjust the precooling temperature, hydrogen flow rate and regeneration cycle to optimize the balance between impurity removal efficiency and energy consumption.

[0067] Through the comprehensive application of the above technical solutions, the present invention solves the problems of low impurity removal efficiency, high energy consumption, and complex operation in the existing hydrogen liquefaction system, and achieves the technical effect of impurity removal efficiency of more than 90% and energy consumption reduction of 30%-50%. At the same time, it has the characteristics of simple operation and strong adaptability, and is suitable for hydrogen liquefaction systems of different scales and types.

[0068] Refer to the following Figures 1 to 5 The process flow of removing impurities by the raw hydrogen purification device 100 is described.

[0069] After the process starts, the raw hydrogen enters the primary precooling unit 101 and is precooled to between -50°C and -100°C, and then enters the secondary precooling unit 102 and is precooled to between -150°C and -200°C. At this time, the gas impurities carried in the raw hydrogen are precooled and separated from the hydrogen, and the impurities enter the low-temperature adsorption unit 103 with the hydrogen gas flow. The airflow residence time in the low-temperature adsorption unit 103 should be guaranteed to be between 10 minutes and 30 minutes to improve the adsorption efficiency of the adsorbent on impurities. The low-temperature purified hydrogen after impurity removal by the low-temperature adsorption unit 103 returns to the primary precooling unit 101 to provide cold capacity for the raw hydrogen, and when the concentration detected by the hydrogen concentration detection unit reaches the preset requirement, it is connected to the cold box of the hydrogen liquefaction system for liquefaction. Otherwise, the low-temperature purified hydrogen output from the primary precooling unit 101 should also be returned to the secondary precooling unit 102 and the low-temperature adsorption unit 103 through the reflux pipeline 112 for further impurity removal until the concentration of the low-temperature purified hydrogen output from the primary precooling unit 101 reaches the preset requirement.

[0070] At the same time, it is also necessary to monitor whether the adsorbent is saturated with adsorption. When it is determined that the adsorbent is saturated with adsorption, it is necessary to perform rewarming, activation gas replacement, activation gas desorption and hydrogen replacement so that the adsorbent can regain its adsorption capacity before continuing with the next round of impurity removal operations.

[0071] In addition, when the cooling capacity of the low-temperature purified hydrogen output from the low-temperature adsorption unit 103 is insufficient, part of the liquefied hydrogen can be drawn from the cold box and input into the primary precooling unit 101 to provide auxiliary cooling capacity.

[0072] In the above process, in order to ensure the efficient operation and safe monitoring of the system, multiple high-precision temperature detection units, pressure detection units and impurity concentration monitors are arranged along the key nodes of the system to form a complete real-time data acquisition network. These detection units and monitors can collect temperature, pressure and impurity content data at the hydrogen outlet in real time, and transmit the data to the remote control system through the communication protocol. The remote control system has a built-in algorithm, which dynamically adjusts the key operating parameters such as the cold trap hydrogen flow rate and regeneration cycle based on the preset process parameter threshold and real-time data change trend, thereby optimizing the impurity removal efficiency and energy consumption performance of the cold trap. For example, when the temperature or pressure fluctuations are detected beyond the preset range, the system will adjust the hydrogen flow rate in time to maintain stable operation. In addition, the system is also equipped with a safety protection mechanism, in which the safety valve, as a core safety component, can automatically open when the pressure in the system exceeds the preset safety value, quickly release the pressure, prevent the equipment from being damaged by overpressure, and ensure the safety and reliability of the overall system. This monitoring and adjustment mechanism not only improves the operating efficiency of the cold trap system, but also significantly reduces the need for manual intervention, providing a strong guarantee for the safe purification of hydrogen.

[0073] Compared with the prior art, the present invention has the significant advantages of high efficiency and energy saving, high-purity hydrogen preparation, extended equipment life, intelligence and automation, process flexibility and adaptability, and environmental protection and safety: through the pre-cooling system and circulation purification design, ultra-low temperature hydrogen is used to exchange heat with raw hydrogen, which significantly reduces the liquefaction energy consumption and improves the overall energy efficiency by about 15-20%; a multi-stage impurity removal process and adsorbent regeneration treatment are adopted to ensure that the hydrogen purity reaches a high standard and extend the equipment life; the intelligent monitoring system collects data in real time and dynamically adjusts the operating parameters to optimize efficiency and ensure safety; the multi-stage process design flexibly adapts to different needs, and the regeneration treatment process reduces the operating cost; liquid nitrogen is used as the low-temperature medium, which meets environmental protection requirements, and the system safety is ensured through nitrogen replacement and other steps, providing an efficient, reliable and economical solution for the field of hydrogen purification and liquefaction.

[0074] The above is only a preferred embodiment of the present invention, and does not limit the present invention in any form. Although the present invention has been disclosed as a preferred embodiment as above, it is not used to limit the present invention. Any technician familiar with the present invention can make some changes or modify the technical contents suggested above into equivalent embodiments without departing from the scope of the technical solution of the present invention. However, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present invention without departing from the content of the technical solution of the present invention still fall within the scope of the solution of the present invention.

Claims

1. A raw hydrogen purification device for a hydrogen liquefaction system, characterized in that: It includes a primary precooling unit, a secondary precooling unit and a low-temperature adsorption unit; The raw hydrogen is precooled to a first temperature range in the first precooling unit and then enters the second precooling unit. After being precooled to a second temperature range in the second precooling unit, it enters the low-temperature adsorption unit for impurity removal and becomes low-temperature purified hydrogen. The low-temperature purified hydrogen returns to the primary precooling unit to provide cooling for the raw hydrogen and is then connected to the cold box of the hydrogen liquefaction system for liquefaction.

2. The raw hydrogen purification device for a hydrogen liquefaction system according to claim 1, characterized in that: The secondary precooling unit comprises a first heat exchange channel and a second heat exchange channel for heat exchange, one end of the first heat exchange channel is connected to the primary precooling unit, and the other end is connected to one end of the low-temperature adsorption unit, and the other end of the low-temperature adsorption unit is connected to the primary precooling unit; Both ends of the second heat exchange channel are respectively connected to an external cold source, so that a refrigerant is supplied into the second heat exchange channel to cool the raw hydrogen gas to the second temperature range for low-temperature separation; The raw hydrogen after low-temperature separation is subjected to low-temperature adsorption by the low-temperature adsorption unit and then returns to the primary precooling unit.

3. The raw hydrogen purification device for a hydrogen liquefaction system according to claim 2, characterized in that: A one-way valve is provided on the connecting pipeline between the first heat exchange channel and the low-temperature adsorption unit, and the one-way valve allows the raw hydrogen after low-temperature separation to flow to the low-temperature adsorption unit in one direction.

4. The raw hydrogen purification device for a hydrogen liquefaction system according to claim 2, characterized in that: It also includes an ultra-low temperature hydrogen introduction pipeline, wherein the ultra-low temperature hydrogen introduction pipeline is connected to the primary precooling unit; Wherein, a first temperature detection unit is provided on the connecting pipeline between the first heat exchange channel and the primary precooling unit, and / or a second temperature detection unit is provided on the connecting pipeline between the low-temperature adsorption unit and the primary precooling unit; When the temperature of the raw hydrogen detected by the first temperature detection unit exceeds the upper limit of the first temperature range, and / or the temperature of the low-temperature purified hydrogen detected by the second temperature detection unit exceeds the upper limit of the second temperature range, the ultra-low temperature hydrogen introduction pipeline is connected to introduce ultra-low temperature hydrogen into the first-level precooling unit to provide auxiliary cooling for the raw hydrogen.

5. The raw hydrogen purification device for a hydrogen liquefaction system according to claim 4, characterized in that: The ultra-low temperature hydrogen introduction pipeline is configured to be connected to a cold box of the hydrogen liquefaction system.

6. The raw hydrogen purification device for a hydrogen liquefaction system according to claim 2, characterized in that: The low-temperature adsorption unit is a regenerable adsorption unit; Wherein, the raw hydrogen purification device further comprises an activation gas introduction pipeline and a venting pipeline, and the activation gas introduction pipeline and the venting pipeline are respectively connected to the low-temperature adsorption unit; A hydrogen concentration detection unit is connected to the low-temperature purified hydrogen output pipeline of the first-stage precooling unit. When the hydrogen concentration detected by the hydrogen concentration detection unit is lower than a preset first concentration threshold, the external supply is cut off, and the activation gas introduction pipeline and the venting pipeline are connected to regenerate the low-temperature adsorption unit.

7. The raw hydrogen purification device for a hydrogen liquefaction system according to claim 6, characterized in that: The process of regenerating the low-temperature adsorption unit includes rewarming, activation gas replacement, activation gas desorption and hydrogen replacement.

8. The raw hydrogen purification device for a hydrogen liquefaction system according to any one of claims 1 to 7, characterized in that: The first temperature range is from -50°C to -100°C; the second temperature range is from -150°C to -200°C.

9. The raw hydrogen purification device for a hydrogen liquefaction system according to any one of claims 1 to 7, characterized in that: The first-stage precooling unit adopts a plate-type heat exchange structure, and the second-stage precooling unit adopts a tube-type heat exchange structure.

10. A hydrogen liquefaction system, characterized in that: It comprises a raw hydrogen purification device for a hydrogen liquefaction system according to any one of claims 1 to 9.

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