Multi-temperature-zone variable-working-condition ortho-parahydrogen continuous catalytic conversion characteristic test system and method

Abstract

The invention provides a multi-temperature-zone variable-working-condition ortho-parahydrogen continuous catalytic conversion characteristic test system and method, and relates to the technical field of ultralow temperature. The system comprises a test device used for cooling raw material hydrogen to a first temperature zone, then cooling the raw material hydrogen to a second temperature zone through an ortho-parahydrogen conversion heat exchanger and converting ortho-hydrogen in the raw material hydrogen into parahydrogen; the control analysis device is used for providing raw material hydrogen, providing a cold source and detecting and analyzing the parahydrogen content in the gas before and after conversion of the ortho-parahydrogen conversion heat exchanger; the auxiliary device is used for providing a high-vacuum environment required by low temperature for the test; the ortho-parahydrogen conversion heat exchanger can take away conversion heat generated in the conversion process while promoting conversion from ortho-hydrogen to parahydrogen; the control analysis device can adjust the proportion of ortho-hydrogen and parahydrogen in the raw material hydrogen. The method applies the system. The continuous catalytic conversion performance and heat exchange performance of the ortho-parahydrogen conversion heat exchanger under different working conditions are explored by adjusting the ortho-parahydrogen content in the raw material hydrogen.

Description

Technical Field

[0001] The present invention relates to the field of ultra-low temperature technology, and in particular to a multi-temperature zone variable working condition normal-parahydrogen continuous catalytic conversion characteristic test system and method. Background Art

[0002] Hydrogen can be produced from fossil energy, industrial by-product gas, water and other hydrogen-containing substances, and is an important industrial raw material and energy carrier. Hydrogen energy refers to the energy released by hydrogen during physical and chemical changes, which can be used in industry, power generation, energy storage, transportation fuel, and mixed with natural gas for industrial and civil gas use.

[0003] Hydrogen mainly appears in the form of chemical compounds, and the usual single substance form is hydrogen (H2). Liquid hydrogen is a deep-cold way to store hydrogen. After being compressed, hydrogen is deep-cooled to below 21 K to become liquid hydrogen, and then stored in a special insulated vacuum container. The density of liquid hydrogen at room temperature and pressure is 845 times that of gaseous hydrogen, and the volume energy density of liquid hydrogen is also several times higher than that of compressed storage, which greatly increases the hydrogen storage capacity of the same volume of hydrogen storage container, and is expected to become the main form of large-scale transportation.

[0004] The conversion of ortho-parahydrogen is one of the key links in hydrogen liquefaction. In the hydrogen molecule H2 composed of two atoms, there are two states, ortho- and para-hydrogen, due to the different directions of the nuclear spins of the two hydrogen atoms. The nuclear spin directions of ortho-hydrogen (o-H2) are the same, while the nuclear spin directions of para-hydrogen (p-H2) are opposite. The equilibrium composition of the ortho- and para-states is related to temperature. At room temperature, equilibrium hydrogen is a mixture of 75% ortho-hydrogen and 25% para-hydrogen, called normal hydrogen (or standard hydrogen), represented by the symbol n-H2. Above room temperature, the equilibrium composition of the ortho-para-state remains unchanged. Below room temperature, the equilibrium composition of the ortho-para-state will change, that is, as the temperature decreases, the percentage of para-hydrogen increases. At standard atmospheric pressure and hydrogen saturation temperature of 20.4 K, the para-hydrogen concentration of equilibrium hydrogen is 99.8%.

[0005] In the process of hydrogen gradually cooling down and liquefying, orthohydrogen will spontaneously convert to parahydrogen and release a large amount of conversion heat, which will cause the liquid hydrogen to vaporize and increase the additional liquefaction energy consumption. This conversion process is not conducive to the long-term storage of liquid hydrogen. The evaporation caused by the conversion heat in one day can even reach more than 20% of the total storage capacity. Therefore, it is necessary to add a catalyst in the liquefaction process to promote the conversion process of orthohydrogen and parahydrogen. Generally, the parahydrogen content in the liquid hydrogen product is required to be above 95% to reduce the evaporation loss of liquid hydrogen caused by the conversion of orthohydrogen and parahydrogen.

[0006] The continuous conversion of para-hydrogen is an important step in achieving large-scale hydrogen liquefaction. Continuous conversion is to remove the conversion heat of para-hydrogen in a timely manner through the cooling fluid in the heat exchanger, so that the hydrogen concentration at the corresponding temperature is always maintained during the conversion process, which makes the comprehensive energy consumption of the hydrogen liquefaction system low.

[0007] From the above, it can be seen that building a multi-temperature zone variable working condition normal-parahydrogen continuous catalytic conversion characteristic test system that can simulate actual industrial production to test the continuous catalytic conversion performance of hydrogen in the ultra-low temperature environment of the liquid hydrogen temperature zone, catalyst performance and other data can provide important reference for the design, use and maintenance of normal-parahydrogen conversion heat exchangers, thereby promoting the development of large-scale hydrogen liquefaction equipment in the gas industry.

[0008] The information disclosed in this background technology section is only intended to deepen the understanding of the overall background technology of the present application, and should not be regarded as an admission or any form of suggestion that the information constitutes the prior art known to those skilled in the art. Summary of the invention

[0009] In view of the above situation, the present invention provides a multi-temperature zone variable working condition normal-parahydrogen continuous catalytic conversion characteristic test system and method, which precools the normal-parahydrogen conversion heat exchanger device through a cold source in a high vacuum and low radiation environment to create an ultra-low temperature test environment for the normal-parahydrogen conversion heat exchanger; an auxiliary device establishes a dynamic high vacuum environment for the internal cavity of the ultra-low temperature vacuum cold box to ensure the realization of multi-temperature zone conditions of liquid hydrogen, thereby providing the required multi-temperature zone environment for the test; by controlling the setting of the low-pressure liquid hydrogen vaporizer and the supporting pipeline in the analysis device, the mixing ratio of the liquid hydrogen vaporized gas in the raw hydrogen can be adjusted, thereby adjusting the normal-parahydrogen content in the raw hydrogen, providing multi-working condition conditions for the test, and at the same time, the temperature zone for the test can be adjusted by adjusting the liquid hydrogen flow rate, providing multi-temperature zone conditions for the test, thereby exploring the continuous catalytic conversion performance of the catalyst under multi-working condition and multi-temperature zone conditions, as well as the heat exchange performance of the normal-parahydrogen conversion heat exchanger.

[0010] To achieve the above object, the present invention provides the following technical solutions: In a first aspect, the present invention provides a multi-temperature zone variable working condition normal and para hydrogen continuous catalytic conversion characteristic test system, comprising: The test device is used to first cool the raw hydrogen to a first temperature zone, then promote the conversion of orthohydrogen in the raw hydrogen into parahydrogen through an ortho-parahydrogen conversion heat exchanger and cool it to a second temperature zone; A control and analysis device, used to provide the raw hydrogen gas to the test device, provide a cold source to the test device, provide a multi-temperature zone environment for the test, and detect and analyze the para-hydrogen content in the gas before and after the conversion of the normal-para-hydrogen conversion heat exchanger; An auxiliary device for establishing a dynamic high vacuum environment in the test device; in: The ortho-parahydrogen conversion heat exchanger is filled with a catalyst for promoting the conversion of ortho-hydrogen into para-hydrogen, and can continuously remove the conversion heat generated during the conversion of ortho-hydrogen into para-hydrogen; The control and analysis device can adjust the ratio of normal-parahydrogen in the raw hydrogen and the temperature zone in which the raw hydrogen undergoes normal-parahydrogen conversion.

[0011] In some embodiments of the present invention, the test device includes an ultra-low temperature vacuum cold box, and a pre-cooling heat exchanger and a normal-para-hydrogen conversion heat exchanger arranged inside the ultra-low temperature vacuum cold box; The ultra-low temperature vacuum cold box is connected to the auxiliary device; The precooling heat exchanger is used to cool the raw hydrogen to the first temperature zone; The ortho-parahydrogen conversion heat exchanger is used to promote the conversion of orthohydrogen in the raw hydrogen into parahydrogen, and at the same time take away the conversion heat in the above conversion process to cool the raw hydrogen to the second temperature zone.

[0012] In some embodiments of the present invention, the precooling heat exchanger has: Pre-cooling cold source channel, used to transport liquid hydrogen; A precooling channel, used for cooling the raw hydrogen to a first temperature zone; The precooling and reheating channel is used to reheat the exhaust gas after the conversion of the normal-parahydrogen conversion heat exchanger.

[0013] In some embodiments of the present invention, the normal-parahydrogen conversion heat exchanger has: A conversion channel for loading catalyst, wherein the raw hydrogen enters the conversion channel after passing through the precooling channel; The conversion cold source channel is connected to the pre-cooling cold source channel.

[0014] In some embodiments of the present invention, resistance measuring points are provided at the inlet and outlet of the conversion channel.

[0015] In some embodiments of the present invention, temperature measuring points are provided at both the inlet and the outlet of the conversion channel, and / or temperature measuring points are provided at both the inlet and the outlet of the conversion cold source channel.

[0016] In some embodiments of the present invention, the control and analysis device comprises: A liquid hydrogen pipeline, wherein the liquid hydrogen pipeline, the conversion cold source channel and the pre-cooling cold source channel are connected in sequence; A low-pressure liquid hydrogen vaporizer, whose liquid phase inlet is connected to the liquid hydrogen pipeline, and whose gas phase outlet is directly or indirectly connected to the raw hydrogen pipeline and the conversion cold source channel respectively; A raw hydrogen pipeline, wherein the raw hydrogen pipeline, the precooling channel, the conversion channel and the precooling and reheating channel are connected in sequence; The analysis interface is used to connect an analysis device, and the analysis device is used to continuously detect the para-hydrogen content in the gas before and after the conversion of the normal-para-hydrogen conversion heat exchanger.

[0017] In some embodiments of the present invention, the analysis device is also used to detect the water content in the system pipeline.

[0018] In some embodiments of the present invention, the control and analysis device further comprises: A nitrogen pipeline, used to provide nitrogen for purging designated pipelines and activating the catalyst; A nitrogen heater, the nitrogen pipeline and the conversion channel are connected through the nitrogen heater.

[0019] In a second aspect, the present invention provides a method for testing the continuous catalytic conversion characteristics of normal and para hydrogen under variable operating conditions in multiple temperature zones, comprising: Activating the catalyst; Connecting the auxiliary device to the test device, and providing a dynamic high vacuum environment to the test device through the auxiliary device; Use nitrogen to purge the pipelines in the system, and stop purging when the dew point in the system pipelines is lower than the preset value; Use raw hydrogen containing a specified ratio of normal and para hydrogen to replace the nitrogen in the system pipeline; when the nitrogen content in the system pipeline is less than a predetermined value, stop the gas supply and maintain the pressure in the system; Allow the cold source to enter the test device, and after the flow rate of the cold source entering the test device is stable, gradually increase the flow rate of the cold source to the flow rate required for precooling under the test condition; The raw hydrogen flow rate reaches the specified test condition flow rate, and the raw hydrogen then enters the test device and is first cooled to the first temperature zone, and then passes through the ortho-parahydrogen conversion heat exchanger to cool to the second temperature zone and convert the orthohydrogen in the raw hydrogen into parahydrogen; The continuous catalytic conversion performance of para-hydrogen and the heat exchange performance of the para-hydrogen conversion heat exchanger are analyzed.

[0020] The embodiments of the present invention have at least the following advantages or beneficial effects: 1. In a high vacuum and low radiation environment, the para-hydrogen conversion heat exchanger device is pre-cooled by a cold source to create an ultra-low temperature test environment for the para-hydrogen conversion heat exchanger.

[0021] 2. The auxiliary device establishes a dynamic high vacuum environment for the test device to ensure the multi-temperature zone conditions of liquid hydrogen, thereby providing the required multi-temperature zone environment for the test.

[0022] 3. The control and analysis device can adjust the mixing ratio of liquid hydrogen vaporization gas in the raw hydrogen, thereby adjusting the content of para-hydrogen in the raw hydrogen, providing multiple operating conditions for the experiment. At the same time, it can adjust the temperature zone where the raw hydrogen undergoes para-hydrogen conversion, providing multiple temperature zone conditions for the experiment, thereby exploring the continuous catalytic conversion performance of the catalyst under multiple operating conditions and multiple temperature zones, as well as the heat exchange performance of the para-hydrogen conversion heat exchanger.

[0023] Other features and advantages of the present invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practicing the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0025] Figure 1 This is a schematic diagram of the structure of a multi-temperature zone variable working condition normal and para-hydrogen continuous catalytic conversion characteristics test system.

[0026] icon: 1-test device, 11-ultra-low temperature vacuum cold box, 12-precooling heat exchanger, 121-precooling cold source channel, 122-precooling channel, 123-precooling reheating channel, 13-normal-para-hydrogen conversion heat exchanger, 131-conversion channel, 132-conversion cold source channel, 2-control and analysis device, 21-liquid hydrogen pipeline, 22-low-pressure liquid hydrogen vaporizer, 23-raw hydrogen pipeline, 24-analysis interface, 25-nitrogen pipeline, 26-nitrogen heater, 27-vent main pipe, 3- auxiliary device, 31- molecular pump set. DETAILED DESCRIPTION

[0027] In the following, only some exemplary embodiments are briefly described. As those skilled in the art can realize, the described embodiments can be modified in various different ways without departing from the spirit or scope of the embodiments of the present invention.

[0028] In the embodiments of the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral one; it can be directly connected, or indirectly connected through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the embodiments of the present invention can be understood according to specific circumstances.

[0029] The embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0030] First, see Figure 1 This embodiment provides a multi-temperature zone variable-condition normal-parahydrogen continuous catalytic conversion characteristics test system, including a test device 1, a control and analysis device 2 and an auxiliary device 3.

[0031] The test device 1 is used to first cool the raw hydrogen to a first temperature zone (e.g., 35 K temperature zone), and then promote the conversion of orthohydrogen in the raw hydrogen to parahydrogen through the ortho-parahydrogen conversion heat exchanger 13 and cool it to a second temperature zone (e.g., 28 K temperature zone). The test device 1 includes an ultra-low temperature vacuum cold box 11 with a reversible sealing function (openable and closable), and a pre-cooling heat exchanger 12 and an ortho-parahydrogen conversion heat exchanger 13 detachably arranged inside the ultra-low temperature vacuum cold box 11.

[0032] A dynamic vacuum environment can be formed inside the ultra-low temperature vacuum cold box 11. The ultra-low temperature vacuum cold box 11 is a cylindrical structure, and its top is connected to the matching inlet and outlet pipes through a forced sealing flange, so that the test device 1 can be disassembled and replaced as a whole under the premise of ensuring an extremely low leakage rate.

[0033] The precooling heat exchanger 12 is used to cool the raw hydrogen in the raw hydrogen pipeline 23 to the first temperature zone. In a specific implementation scenario, the precooling heat exchanger 12 is a plate-fin heat exchanger, which can achieve multi-channel heat exchange and has a good heat exchange effect. The precooling heat exchanger 12 has a precooling cold source channel 121, a precooling channel 122 and a precooling reheating channel 123.

[0034] The precooling cold source channel 121 is used to transport liquid hydrogen; the precooling heat exchanger 12 uses liquid hydrogen as a cold source.

[0035] The pre-cooling channel 122 is used to cool the raw hydrogen in the raw hydrogen pipeline 23 to the first temperature zone.

[0036] The precooling and reheating channel 123 is used to reheat the exhaust gas after conversion by the normal-para-hydrogen conversion heat exchanger 13.

[0037] The ortho-parahydrogen conversion heat exchanger 13 is used to promote the conversion of orthohydrogen in the raw hydrogen into parahydrogen, and at the same time take away the conversion heat in the above conversion process to cool the raw hydrogen to the second temperature zone. In a specific implementation scenario, the ortho-parahydrogen conversion heat exchanger 13 is a plate-fin heat exchanger, which can realize multi-channel heat exchange and has a good heat exchange effect; the ortho-parahydrogen conversion heat exchanger 13 is detachably arranged in the ultra-low temperature vacuum cold box 11. The ortho-parahydrogen conversion heat exchanger 13 has a conversion channel 131 and a conversion cold source channel 132 inside.

[0038] The conversion channel 131 is filled with a catalyst for promoting the conversion of orthohydrogen into parahydrogen. The filling method of the catalyst is not limited. Temperature measuring points are set at the inlet and outlet of the conversion channel 131. Resistance measuring points are set at the inlet and outlet of the conversion channel 131.

[0039] The conversion cold source channel 132 is connected to the pre-cooling cold source channel 121; the normal-parahydrogen conversion heat exchanger 13 uses liquid hydrogen as a cold source. Temperature measuring points are set at the inlet and outlet of the conversion cold source channel 132.

[0040] The control and analysis device 2 is used to provide raw hydrogen containing a specified normal-parahydrogen ratio to the test device 1, provide a cold source to the test device 1, provide a multi-temperature zone environment for the test, and detect and analyze the parahydrogen content in the gas before and after the conversion of the normal-parahydrogen conversion heat exchanger 13. The control and analysis device can adjust the normal-parahydrogen ratio in the raw hydrogen and the temperature zone in which the raw hydrogen undergoes normal-parahydrogen conversion. The control and analysis device 2 includes a liquid hydrogen pipeline 21, a low-pressure liquid hydrogen vaporizer 22, a raw hydrogen pipeline 23, an analysis interface 24, a nitrogen pipeline 25, a nitrogen heater 26 and a venting main pipe 27.

[0041] The liquid hydrogen pipeline 21, the conversion cold source channel 132, the pre-cooling cold source channel 121 and the venting main pipe 27 are connected in sequence. In a specific implementation scenario, the outlet of the conversion cold source channel 132 can also be directly connected to the venting main pipe 27.

[0042] The liquid phase inlet of the low-pressure liquid hydrogen vaporizer 22 is connected to the liquid hydrogen pipeline 21, and the low-pressure liquid hydrogen vaporizer 22 vaporizes the liquid hydrogen to obtain liquid hydrogen vaporized gas; the gas phase outlet of the low-pressure liquid hydrogen vaporizer 22 is directly or indirectly connected to the raw hydrogen pipeline 23 and the conversion cold source channel 132 respectively.

[0043] The raw hydrogen pipeline 23, the precooling channel 122, the conversion channel 131, the precooling and reheating channel 123 and the venting main pipe 27 are connected in sequence.

[0044] The analysis interface 24 is used to connect an analysis device, which is used to detect the parahydrogen content in the gas before and after the conversion of the normal parahydrogen conversion heat exchanger 13, and the water content in the system pipeline; wherein the purpose of testing the water content is to check and confirm the pipeline purging effect of the entire system. In a specific implementation scenario, the analysis device includes a normal parahydrogen content chromatograph and a dew point meter; the normal parahydrogen content chromatograph is used to continuously detect the parahydrogen content in the gas before and after the conversion of the normal parahydrogen conversion heat exchanger 13; the dew point meter is used to continuously detect the water content in the system pipeline.

[0045] The nitrogen pipeline 25 is used to provide nitrogen for purging the designated pipeline and activating the catalyst in the conversion channel 131, wherein the purpose of purging the designated pipeline is to discharge water vapor and prevent freezing. In a specific implementation scenario, the raw hydrogen pipeline 23, the liquid hydrogen pipeline 21, the conversion channel 131 and the venting main pipe 27 are all connected to the nitrogen pipeline 25 to discharge water vapor in the entire system to prevent freezing.

[0046] The nitrogen heater 26 connects the nitrogen pipeline 25 and the conversion channel 131 to activate the catalyst in the conversion channel 131 through the heated nitrogen. In a specific implementation scenario, the nitrogen heater 26 is an electric heater.

[0047] All hydrogen outlets of the test device 1 are collected in the exhaust main pipe 27 to exhaust the tail gas discharged from the test device 1. It can be understood that in order to achieve safe exhaust, the tail gas can be reheated by corresponding heat exchange equipment before exhausting.

[0048] The working principle of the above-mentioned control and analysis device 2 is: the catalyst in the conversion channel 131 is activated by heated nitrogen. The nitrogen pipeline 25 is used to purge the designated pipeline to discharge the water vapor in the entire system to prevent freezing. Through the setting of the low-pressure liquid hydrogen vaporizer 22 and the supporting pipelines, the mixing ratio of the liquid hydrogen vaporization gas in the raw hydrogen can be adjusted, thereby adjusting the content of normal para-hydrogen in the raw hydrogen, providing multiple working conditions for the experiment, and at the same time, the temperature zone for normal para-hydrogen conversion can be adjusted by adjusting the liquid hydrogen flow rate, providing multiple temperature zone conditions for the experiment, thereby exploring the continuous catalytic conversion performance of the catalyst under multiple working conditions and multiple temperature zone conditions, as well as the heat exchange performance of the normal para-hydrogen conversion heat exchanger 13.

[0049] The auxiliary device 3 is used to establish a dynamic high vacuum environment for the internal cavity of the ultra-low temperature vacuum cold box 11 to ensure the multi-temperature zone conditions of liquid hydrogen, thereby providing a multi-temperature zone environment for the experiment. In a specific implementation scenario, the auxiliary device 3 includes a molecular pump group 31 connected to the ultra-low temperature vacuum cold box 11.

[0050] The above-mentioned devices and components are connected through process pipelines and valves, and the low-temperature pipelines and valves are covered with insulation layers to reduce the cold loss of the entire system.

[0051] In combination with the above contents, the working principle of the above multi-temperature zone variable working condition normal and para-hydrogen continuous catalytic conversion characteristics test system is: After the raw hydrogen passes through the raw hydrogen pipeline 23 and the precooling channel 122, it enters the conversion channel 131, and promotes the conversion of orthohydrogen into parahydrogen under the action of the catalyst, and then after being reheated in the precooling and reheating channel 123, it is emptied through the venting main pipe 27. In the above process, the conversion heat generated is taken away by liquid hydrogen to achieve continuous catalytic conversion. Before being emptied through the venting main pipe 27, the parahydrogen content in the gas before and after the conversion of the ortho-parahydrogen conversion heat exchanger 13 is continuously detected through the analysis interface 24, and the catalytic reaction rate, air velocity and other results of the ortho-parahydrogen conversion heat exchanger 13 can be calculated in combination with the test operation parameters. In addition, the resistance measurement points at the inlet and outlet of the conversion channel 131 can be used to analyze the resistance characteristics of the conversion channel 131 of the ortho-parahydrogen conversion heat exchanger 13 after the catalyst is loaded; the temperature measurement points arranged at each inlet and outlet of the ortho-parahydrogen conversion heat exchanger 13 can be used to comprehensively analyze the heat exchange performance of the ortho-parahydrogen conversion heat exchanger 13. The above system can provide multiple temperature zones and multiple operating conditions for the test, and obtain data such as the continuous catalytic conversion performance, catalyst performance and heat exchange performance of the raw hydrogen in the ultra-low temperature environment of the liquid hydrogen temperature zone, thereby providing important reference for the design, use and maintenance of the normal-parahydrogen conversion heat exchanger 13.

[0052] Second, see Figure 1 The present embodiment provides a multi-temperature zone variable working condition normal para-hydrogen continuous catalytic conversion characteristic test method, which uses the multi-temperature zone variable working condition normal para-hydrogen continuous catalytic conversion characteristic test system. The multi-temperature zone variable working condition normal para-hydrogen continuous catalytic conversion characteristic test method comprises the following steps: Step S1: Test preparation: Step S11, confirm the normal-parahydrogen conversion heat exchanger 13 to be tested, prepare the raw hydrogen, liquid hydrogen for providing cooling capacity, and nitrogen for system replacement and purge, and then press Figure 1 Connect the various devices as shown.

[0053] Step S12, activating the catalyst: The valve on the nitrogen pipeline 25 is opened, and the nitrogen heater 26 is turned on, so that the nitrogen is heated to 150° C. by the nitrogen heater 26 and then enters the conversion channel 131 of the normal-parahydrogen conversion heat exchanger 13, and the catalyst is heated and activated and then discharged from the vent main pipe 27, and then the nitrogen heater 26 and the valves on the nitrogen pipeline 25 are closed.

[0054] Step S13, start the vacuum pump and purge the test gas path: The auxiliary device 3 is connected to the ultra-low temperature vacuum cold box 11, and the auxiliary device 3 is turned on to evacuate the cavity of the ultra-low temperature vacuum cold box 11 to 1×10 -3 pa; the auxiliary device 3 continues to operate during the test to maintain the dynamic high vacuum environment inside the ultra-low temperature vacuum cold box 11; The nitrogen in the nitrogen pipeline 25 is used to purge the multi-temperature zone variable working condition normal-parahydrogen continuous catalytic conversion characteristic test system to purge the impurity gas cleanly, and the dew point meter is connected through the analysis interface 24 to continuously detect the exhaust gas composition at the outlet of the conversion channel 131. When the dew point is lower than the preset value (-60°C), the purge is stopped; After the purge is completed, the nitrogen in the system pipeline is replaced with raw hydrogen and liquid hydrogen vaporized gas, and the ortho-parahydrogen content chromatograph is connected to the analysis interface 24 to continuously detect the exhaust gas components at the outlet of the conversion channel 131. When the nitrogen content is less than the predetermined value (1ppm), the gas supply is stopped and the pressure in the system is maintained.

[0055] Step S2: System precooling and pressure maintenance: A portion of the liquid hydrogen in the liquid hydrogen pipeline 21 is allowed to enter the low-pressure liquid hydrogen vaporizer 22 to be vaporized into room-temperature hydrogen and then enter the system; after the liquid hydrogen flow rate entering the ultra-low temperature vacuum cold box 11 is stabilized, the liquid hydrogen (cold source) flow rate is gradually increased to the flow rate required for pre-cooling under the test conditions to cool the ultra-low temperature vacuum cold box 11, and the temperature of the normal-para-hydrogen conversion heat exchanger 13 is monitored through the temperature measuring points located at the inlet and outlet of the conversion cold source channel 132 to about 20 K in the liquid hydrogen temperature zone; The liquid hydrogen after heat exchange in the normal-para-hydrogen conversion heat exchanger 13 enters the precooling heat exchanger 12 for reheating (and also serves as a cold source for the precooling heat exchanger 12), and is then safely discharged into the atmosphere through the vent main pipe 27.

[0056] Step S3: Experimental test: Step S31, open the valve on the raw hydrogen pipeline 23, and adjust the valve so that the raw hydrogen flow rate reaches the specified test condition flow rate, record the operation time as the starting point of the test, and then the raw hydrogen enters the cavity of the ultra-low temperature vacuum cold box 11, and is cooled to the first temperature zone by liquid hydrogen in the pre-cooling heat exchanger 12; Step S32, the raw hydrogen then enters the conversion channel 131 of the normal-parahydrogen conversion heat exchanger 13, and realizes continuous catalytic conversion of normal-parahydrogen after the catalyst catalytic conversion and liquid hydrogen take away the conversion heat; the raw hydrogen is cooled to 28 K in the conversion channel 131, and the parahydrogen content reaches about 97%, and then exits the normal-parahydrogen conversion heat exchanger 13 and enters the precooling and reheating channel 123 of the precooling heat exchanger 12 for reheating, and then is safely discharged into the atmosphere through the venting main pipe 27; Step S34, analyzing the continuous catalytic conversion performance of ortho-parahydrogen of the ortho-parahydrogen conversion heat exchanger 13: allowing a portion of the gas at the inlet of the precooling channel 122 to enter the analysis device through the analysis interface 24, and analyzing the composition or related properties of the gas before the test; after the test is completed, allowing a portion of the gas at the outlet of the precooling and reheating channel 123 to enter the analysis device through the analysis interface 24, continuously detecting and analyzing the composition or related properties of the gas after the test, and then comparing the raw hydrogen and combining the test operation parameters to calculate the catalytic reaction rate, space velocity and other results; Step S35, by setting resistance measuring points at the inlet and outlet of the conversion channel 131, analyzing the resistance characteristics of the conversion channel 131 of the normal-parahydrogen conversion heat exchanger 13 after the catalyst is loaded; by arranging temperature measuring points at the inlet and outlet of the conversion channel 131 and the conversion cold source channel 132, analyzing the heat exchange performance of the normal-parahydrogen conversion heat exchanger 13.

[0057] Step S4, stop the test: Step S41, stopping the cooling of the ultra-low temperature vacuum cold box 11 by liquid hydrogen, and gradually closing the valve at the inlet of the low-pressure liquid hydrogen vaporizer 22, and stopping the introduction of vaporized hydrogen into the conversion channel 131; Step S42, stop introducing raw material hydrogen; Step S43, use the room temperature nitrogen in the nitrogen pipeline 25 to purge the system, and allow the room temperature nitrogen to enter the ultra-low temperature vacuum cold box 11 to restore the temperature of the normal-parahydrogen conversion heat exchanger 13, the precooling heat exchanger 12 and the supporting pipelines to room temperature.

[0058] Step S44: After the normal-parahydrogen conversion heat exchanger 13, the precooling heat exchanger 12 and the supporting pipelines are restored to room temperature, the system is pressurized to 50 kPa using room temperature nitrogen purge, and then all valves of the system are closed, and the auxiliary device 3 is gradually closed. At this point, all equipment on the test platform stops running, and the test is ended.

[0059] In combination with the above content, this embodiment has at least the following beneficial effects: 1. In a high vacuum and low radiation environment, the para-hydrogen conversion heat exchanger 13 device is pre-cooled by a cold source (liquid hydrogen) to create an ultra-low temperature test environment for the para-hydrogen conversion heat exchanger 13.

[0060] 2. A dynamic high vacuum environment is established for the test device 1 (inner cavity of the ultra-low temperature vacuum cold box 11) through the auxiliary device 3 to ensure the realization of multi-temperature zone conditions of liquid hydrogen, thereby providing the required multi-temperature zone environment for the test (the raw hydrogen in the raw hydrogen pipeline 23 is cooled to the first temperature zone through the pre-cooling heat exchanger 12, and the raw hydrogen after passing through the pre-cooling heat exchanger 12 is cooled to the second temperature zone through the normal-para-hydrogen conversion heat exchanger 13).

[0061] It should be noted that, in the present embodiment, the first temperature zone is the 35 K temperature zone, and the second temperature zone is the 28 K temperature zone. In other embodiments, the first temperature zone and the second temperature zone may include specified temperature zones in the 80 K ~ 28 K temperature range. It can be seen from the foregoing that the adjustment of the temperature zone can be achieved by adjusting the liquid hydrogen flow rate.

[0062] 3. The control and analysis device (low-pressure liquid hydrogen vaporizer 22 and supporting pipelines) can adjust the mixing ratio of liquid hydrogen vaporization gas in the raw hydrogen, thereby adjusting the content of para-hydrogen in the raw hydrogen, providing multiple operating conditions for the experiment, and at the same time can adjust the temperature zone in which the raw hydrogen undergoes para-hydrogen conversion (achieved by adjusting the liquid hydrogen flow rate), providing multiple temperature zone conditions for the experiment, thereby exploring the continuous catalytic conversion performance of the catalyst in the para-hydrogen conversion heat exchanger 13 under multiple operating conditions and multiple temperature zones, as well as the heat exchange performance of the para-hydrogen conversion heat exchanger 13.

[0063] Fourth, the resistance measurement points at the inlet and outlet of the conversion channel 131 are used to analyze the resistance characteristics of the conversion channel 131 of the normal parahydrogen conversion heat exchanger 13 after the catalyst is loaded; the temperature measurement points arranged at each inlet and outlet of the normal parahydrogen conversion heat exchanger 13 are used to analyze the heat exchange performance of the normal parahydrogen conversion heat exchanger 13, thereby providing an important reference for the design, use and maintenance of the normal parahydrogen conversion heat exchanger 13. This application has built a test platform (referring to the above system) for the characteristics of gas in a multi-temperature zone ultra-low temperature environment of liquid hydrogen, which has the advantages of a wide range of working conditions, a variety of working conditions, simple operation, and reliable data.

[0064] 5. It can be seen from the foregoing that the normal-parahydrogen conversion heat exchanger 13 has different catalyst filling methods, and the normal-parahydrogen conversion heat exchanger 13 can be disassembled and replaced; by replacing the normal-parahydrogen conversion heat exchanger 13 with different catalyst filling methods, the continuous catalytic conversion performance of the catalyst under different catalyst filling methods, as well as the catalytic performance and heat exchange performance of the normal-parahydrogen conversion heat exchanger 13 in the liquid hydrogen temperature range can be tested.

[0065] Finally, it should be noted that the above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. In the absence of conflicts, the embodiments of the present application and the features in the embodiments may be arbitrarily combined with each other. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention shall be included in the protection scope of the present invention.

Claims

1. A multi-temperature zone variable working condition normal and para-hydrogen continuous catalytic conversion characteristics test system, characterized in that: include: The test device is used to first cool the raw hydrogen to a first temperature zone, then promote the conversion of orthohydrogen in the raw hydrogen into parahydrogen through an ortho-parahydrogen conversion heat exchanger and cool it to a second temperature zone; A control and analysis device, used to provide the raw hydrogen gas to the test device, provide a cold source to the test device, provide a multi-temperature zone environment for the test, and detect and analyze the para-hydrogen content in the gas before and after the conversion of the normal-para-hydrogen conversion heat exchanger; An auxiliary device for establishing a dynamic high vacuum environment in the test device; in: The ortho-parahydrogen conversion heat exchanger is filled with a catalyst for promoting the conversion of ortho-hydrogen into para-hydrogen, and can continuously remove the conversion heat generated during the conversion of ortho-hydrogen into para-hydrogen; The control and analysis device can adjust the ratio of normal-parahydrogen in the raw hydrogen and the temperature zone in which the raw hydrogen undergoes normal-parahydrogen conversion.

2. The multi-temperature zone variable working condition normal-parahydrogen continuous catalytic conversion characteristic test system according to claim 1 is characterized in that: The test device comprises an ultra-low temperature vacuum cold box, and a pre-cooling heat exchanger and a normal-para-hydrogen conversion heat exchanger arranged inside the ultra-low temperature vacuum cold box; The ultra-low temperature vacuum cold box is connected to the auxiliary device; The precooling heat exchanger is used to cool the raw hydrogen to the first temperature zone; The ortho-parahydrogen conversion heat exchanger is used to promote the conversion of orthohydrogen in the raw hydrogen into parahydrogen, and at the same time take away the conversion heat in the above conversion process to cool the raw hydrogen to the second temperature zone.

3. The multi-temperature zone variable working condition normal-parahydrogen continuous catalytic conversion characteristic test system according to claim 2 is characterized in that: The precooling heat exchanger has: Pre-cooling cold source channel, used to transport liquid hydrogen; A precooling channel, used for cooling the raw hydrogen to a first temperature zone; The precooling and reheating channel is used to reheat the exhaust gas after the conversion of the normal-parahydrogen conversion heat exchanger.

4. The multi-temperature zone variable working condition normal-parahydrogen continuous catalytic conversion characteristic test system according to claim 3 is characterized in that: The para-hydrogen conversion heat exchanger has the following features: A conversion channel for loading catalyst, wherein the raw hydrogen enters the conversion channel after passing through the precooling channel; The conversion cold source channel is connected to the pre-cooling cold source channel.

5. The multi-temperature zone variable working condition normal-parahydrogen continuous catalytic conversion characteristic test system according to claim 4 is characterized in that: The inlet and outlet of the conversion channel are both provided with resistance measuring points.

6. The multi-temperature zone variable working condition normal-parahydrogen continuous catalytic conversion characteristic test system according to claim 4 is characterized in that: Temperature measuring points are provided at the inlet and outlet of the conversion channel, and / or temperature measuring points are provided at the inlet and outlet of the conversion cold source channel.

7. The multi-temperature zone variable working condition normal-parahydrogen continuous catalytic conversion characteristic test system according to any one of claims 4 to 6, characterized in that: The control and analysis device comprises: A liquid hydrogen pipeline, wherein the liquid hydrogen pipeline, the conversion cold source channel and the pre-cooling cold source channel are connected in sequence; A low-pressure liquid hydrogen vaporizer, whose liquid phase inlet is connected to the liquid hydrogen pipeline, and whose gas phase outlet is directly or indirectly connected to the raw hydrogen pipeline and the conversion cold source channel respectively; A raw hydrogen pipeline, wherein the raw hydrogen pipeline, the precooling channel, the conversion channel and the precooling and reheating channel are connected in sequence; The analysis interface is used to connect an analysis device, and the analysis device is used to continuously detect the para-hydrogen content in the gas before and after the conversion of the normal-para-hydrogen conversion heat exchanger.

8. The multi-temperature zone variable working condition normal-parahydrogen continuous catalytic conversion characteristic test system according to claim 7 is characterized in that: The analysis device is also used to detect the water content in the system pipeline.

9. The multi-temperature zone variable working condition normal-parahydrogen continuous catalytic conversion characteristic test system according to claim 7 is characterized in that: The control and analysis device also includes: A nitrogen pipeline, used to provide nitrogen for purging designated pipelines and activating the catalyst; A nitrogen heater, the nitrogen pipeline and the conversion channel are connected through the nitrogen heater.

10. A multi-temperature zone variable working condition normal para-hydrogen continuous catalytic conversion characteristics test method, which uses the multi-temperature zone variable working condition normal para-hydrogen continuous catalytic conversion characteristics test system according to any one of claims 1 to 9, and the multi-temperature zone variable working condition normal para-hydrogen continuous catalytic conversion characteristics test method comprises: Activating the catalyst; Connecting the auxiliary device to the test device, and providing a dynamic high vacuum environment to the test device through the auxiliary device; Use nitrogen to purge the pipelines in the system, and stop purging when the dew point in the system pipelines is lower than the preset value; Use raw hydrogen containing a specified ratio of normal and para hydrogen to replace the nitrogen in the system pipeline; when the nitrogen content in the system pipeline is less than a predetermined value, stop the gas supply and maintain the pressure in the system; Allow the cold source to enter the test device, and after the flow rate of the cold source entering the test device is stable, gradually increase the flow rate of the cold source to the flow rate required for precooling under the test condition; The raw hydrogen flow rate reaches the specified test condition flow rate, and the raw hydrogen then enters the test device and is first cooled to the first temperature zone, and then passes through the ortho-parahydrogen conversion heat exchanger to cool to the second temperature zone and convert the orthohydrogen in the raw hydrogen into parahydrogen; The continuous catalytic conversion performance of para-hydrogen and the heat exchange performance of the para-hydrogen conversion heat exchanger are analyzed.

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