CN116429947A - Hydrogen flow heat transfer and catalytic conversion test platform using low-temperature helium as cold source - Google Patents

Abstract

The invention discloses a hydrogen flow heat transfer and catalytic conversion test platform using low-temperature helium as a cold source. The normal-temperature and high-pressure hydrogen passes through a regenerator and a liquid nitrogen bath pre-converter and enters a heat exchange test unit after reaching a temperature close to liquid nitrogen; The regenerators are respectively arranged upstream and downstream of the liquid nitrogen bath pre-reformer, and exchange heat with the low-temperature hydrogen that flows back after the heat exchange test unit, and respectively recover the cold energy above and below the liquid nitrogen temperature zone; the liquid nitrogen bath pre-reformer The raw material hydrogen is pre-cooled and pre-reformed; the helium refrigeration unit provides cooling capacity, and the helium cooled by the cold surface reaches a specific temperature through the temperature control and flow control equipment; the heat exchange can be adjusted through a series of bypass valves The temperature, flow rate, and parahydrogen concentration at the inlet of the test unit are used to obtain various working condition data. The test platform of the present invention can reach below the liquid nitrogen temperature zone, and test the performance of different working conditions and different structure heat exchange units, and obtain the hydrogen heat transfer, flow and conversion data between the liquid nitrogen temperature zone and the liquid hydrogen temperature zone .

Description

A hydrogen flow heat transfer and catalytic conversion test using low-temperature helium as a cold source platform

technical field

The invention belongs to the field of low-temperature hydrogen heat exchange flow and conversion, and in particular relates to a test platform for hydrogen flow heat transfer and catalytic conversion using low-temperature helium as a cold source.

Background technique

Hydrogen has two spin isomers, orthohydrogen and parahydrogen. At room temperature, the concentration ratio of ortho-parahydrogen in equilibrium hydrogen is 3:1. As the temperature decreases, the corresponding equilibrium parahydrogen concentration will gradually increase. , orthohydrogen will spontaneously and slowly convert to parahydrogen with the release of heat. If the ortho-parahydrogen conversion is not carried out in advance, the orthohydrogen in the liquefied product will spontaneously and slowly convert to parahydrogen and release heat, resulting in evaporation loss. Therefore, the ortho-parahydrogen conversion is an indispensable and important link in hydrogen liquefaction.

The spontaneous conversion of ortho-parahydrogen is very slow, and catalysts are often used to accelerate the ortho-parahydrogen reaction in the hydrogen liquefaction process. According to the conversion conditions, the current common reaction methods include adiabatic conversion, isothermal conversion and continuous conversion, among which continuous conversion is considered to be the most efficient. In order to realize the continuous conversion of ortho-parahydrogen, the common method is to place the catalyst in the hydrogen liquefaction heat exchanger , combining the heat exchange flow process of hydrogen with the conversion process, so that the conversion occurs continuously during the cooling process.

For example, the Chinese patent literature with the publication number CN114353563A discloses a combined normal-parahydrogen continuous conversion low-temperature hydrogen plate-fin heat exchanger in different temperature zones, including a plurality of heat exchangers connected in combination, and each heat exchanger includes multiple The main body of the heat exchanger is composed of evenly arranged heat exchange fins and partitions; the heat exchanger head at one end of the heat exchanger body is provided with a hot fluid inlet and a cold fluid outlet, and the heat exchanger head at the other end There is a hot fluid outlet and a cold fluid inlet; the hot fluid inlet communicates with the hot fluid outlet through the hot fluid channel in the heat exchanger body, and the cold fluid outlet communicates with the hot fluid outlet through the cold fluid channel in the heat exchanger body. The cold fluid inlet is connected; with the temperature gradient direction, each heat exchanger corresponds to a heat exchange temperature zone; each heat exchanger has at least one filling section in the hot fluid channel, and different filling sections are set in different filling sections. Highly active ortho-parahydrogen conversion catalyst.

The Chinese patent document with the publication number CN103836333A discloses a parahydrogen adiabatic conversion refrigeration device, which mainly includes a liquid hydrogen storage tank, a converter, a catalyst, an orifice, a hydrogen guide pipe, a condensation heat exchanger, a vent outlet pipe and a valve. . The top of the liquid hydrogen storage tank is equipped with a converter, an orifice, a hydrogen guide pipe and a condensation heat exchanger. The converter is equipped with a parahydrogen conversion catalyst. One end of the orifice is connected to the converter, and the other end is connected to the hydrogen guide pipe. The two ends of the heater are respectively connected with the hydrogen guide pipe and the vent outlet pipe, and the vent outlet pipe extends out of the liquid hydrogen storage tank and is connected with the valve.

For a heat exchanger that combines the heat exchange flow process with the ortho-parahydrogen conversion process, the flow channel of the heat exchanger needs to be filled with catalyst, and its structure is more complicated than that of ordinary heat exchangers. Heat flow processes are also more unpredictable. Therefore, the experimental data of continuous conversion is very limited, especially below the temperature of liquid nitrogen (78K), and the lack of relevant data also limits the industrial application of this method. Accurate and reliable heat transfer flow and conversion data at low temperatures are urgently needed to provide reference for the design of ortho-parahydrogen conversion in the hydrogen liquefaction process and promote the application of continuous conversion in the hydrogen liquefaction industry.

Contents of the invention

The invention provides a hydrogen flow heat transfer and catalytic conversion test platform using low-temperature helium as a cold source, which can obtain a series of basic data such as temperature distribution, pressure drop, catalyst dosage, ortho-parahydrogen concentration under different working conditions.

A hydrogen flow heat transfer and catalytic conversion test platform using low-temperature helium as a cold source, used to test the heat exchange test unit, including: gas distribution system, primary regenerator, liquid nitrogen bath pre-reformer, secondary stage regenerator, helium refrigeration unit, reheater and gas chromatograph;

Wherein, the gas distribution system includes a high-pressure hydrogen cylinder, a high-pressure nitrogen cylinder and a vacuum pump, and the high-pressure nitrogen cylinder is located on a bypass branch of the output pipeline of the high-pressure hydrogen cylinder and connected to the vacuum pump;

The high-pressure hydrogen cylinder is connected in series with a hydrogen flow meter and a hydrogen flow regulating valve and is divided into two branches, one of which flows through the thermal fluid side of the reheater, the thermal fluid side of the primary regenerator, and the liquid The ortho-parahydrogen catalytic coil in the nitrogen bath pre-reformer; the other branch flows through the concentration bypass valve and then enters the liquid nitrogen bath pre-reformer, and merges with the hydrogen flowing through the ortho-parahydrogen catalytic coil;

The combined hydrogen flows through the hot fluid side of the secondary regenerator and the hot fluid side of the heat exchange test unit in sequence, and then divides into two paths, one of which flows through the cold fluid side of the reheater and the temperature bypass valve in sequence, The other path flows through the cold fluid side of the secondary regenerator and the primary regenerator in sequence;

The heat exchange test unit is filled with an ortho-parahydrogen conversion catalyst in the flow channel on the hot fluid side, and hydrogen undergoes a flow heat exchange process accompanied by catalytic conversion in the flow channel; the cold fluid side of the heat exchange test unit is connected to a helium refrigeration unit, and the helium The air refrigeration unit is a closed cycle, providing cold fluid for the heat exchange test unit;

The gas chromatograph is connected to the hydrogen exhaust pipeline at the outlet of the cold fluid side of the primary regenerator and the hydrogen confluence pipeline at the end of the liquid nitrogen bath pre-reformer, and uses standard hydrogen in a high-pressure hydrogen cylinder as a carrier gas. Measure the ortho-parahydrogen concentration in the hydrogen evacuation line and the hydrogen confluence line.

In the present invention, the normal-temperature high-pressure hydrogen comes from a high-pressure gas cylinder, and the outlet pressure of the gas cylinder is controlled by a safety valve, and enters the heat exchange test unit after reaching a temperature close to liquid nitrogen through a regenerator and a liquid nitrogen bath pre-reformer; the first-stage regenerator The two-stage regenerator and regenerator are respectively arranged upstream and downstream of the liquid nitrogen bath pre-reformer to exchange heat with the low-temperature hydrogen that flows back after the heat exchange test unit, and recover the cooling capacity above and below the liquid nitrogen temperature zone respectively. The liquid nitrogen bath pre-reformer pre-cools and pre-reforms the raw material hydrogen, reducing the heat load borne by the helium refrigeration system. The helium refrigeration unit adopts a closed cycle, and the three-stage series refrigerator provides cooling capacity, and the helium cooled by the cold surface reaches a specific temperature through temperature control and flow control equipment. Through a series of bypass valves, the temperature, flow rate and concentration of ortho-parahydrogen at the inlet of the heat exchange test unit can be adjusted, and the heat exchange test unit can be replaced at the same time. Therefore, the test platform of the present invention can reach below the liquid nitrogen temperature zone, and test the performance of heat exchange units with different structures under different working conditions, and obtain the hydrogen heat exchange, flow, Convert data.

Further, the first-stage regenerator, the liquid nitrogen bath pre-reformer, the second-stage regenerator, the heat exchange test unit and the reheater are all placed in a low-temperature Dewar and subjected to vacuum insulation treatment.

Further, the first-stage regenerator, the second-stage regenerator and the reheater all adopt spiral tube heat exchangers.

Further, the heat exchange test unit includes a hydrogen inlet, a hydrogen outlet, a helium inlet and a helium outlet, and each inlet and outlet is provided with a VCR interface to connect with the pipeline; wherein, a branch is provided on the connecting pipeline of the hydrogen inlet as a catalyst filling Entrance.

Further, the hydrogen from the high-pressure hydrogen cylinder is divided into two branches at room temperature, the flow of the two branches is regulated by the concentration bypass valve at room temperature, and remixed at the end of the liquid nitrogen bath pre-reformer;

By adjusting the concentration bypass valve to adjust the flow rate of hydrogen entering the liquid nitrogen bath pre-reformer for pre-reformation, the concentration adjustment of the hydrogen inlet on the heat exchange test unit is realized.

Furthermore, the low-temperature hydrogen gas from the hydrogen outlet on the heat exchange test unit is divided into two paths, one path is returned to the secondary regenerator as a cold fluid to recover its cooling capacity, and the other path of low-temperature hydrogen gas is rewarmed by the reheater, and then passed through the temperature bypass valve back emptying;

The temperature regulation of the hydrogen gas inlet on the heat exchange test unit is realized by adjusting the flow rate of hydrogen gas entering the first-stage regenerator and the second-stage regenerator as cold fluid through the temperature bypass valve at room temperature.

Further, the outer wall of the heat exchange test unit and the fluid partition are provided with temperature measurement points for measuring the temperature of the wall to convert the temperature distribution of the fluid.

Further, the ortho-parahydrogen catalysis coil is completely submerged in the liquid nitrogen in the liquid nitrogen bath pre-converter, and the ortho-parahydrogen conversion catalyst is filled inside the ortho-parahydrogen catalysis coil.

Further, the liquid nitrogen bath pre-reformer adopts multi-layer insulation, and the nitrogen gas generated by evaporation is discharged from the nitrogen pressure relief pipe.

Compared with the prior art, the present invention has the following beneficial effects:

1. The present invention adopts multi-stage refrigerators in series, and adopts multi-stage regenerators to make full use of the cooling capacity, so that the temperature of the heat exchange test unit can reach between the temperature range of liquid nitrogen and liquid hydrogen. The low-temperature cold source is obtained while the hydrogen cold source is avoided, the hydrogen consumption is reduced and the safety of the system is improved.

2. The present invention can realize the adjustment of temperature, flow rate, and para-hydrogen concentration, and the inlet state of the thermal fluid hydrogen in the heat exchange test unit can be adjusted through a flow regulating valve or a bypass valve, realizing temperature, flow rate, and para-hydrogen concentration, etc. The decoupling of working condition parameters, and the cooling capacity provided by the cold fluid is adjusted by the flow rate of the helium refrigeration cycle, so as to measure the basic data of heat exchange flow and catalytic conversion under different working conditions.

3. The heat exchange test unit of the present invention is connected to the pipeline through the VCR interface, and the sample can be replaced, and the heat exchange units of different structures and types can be tested, so heat exchange units of different flow channel sizes or structure types can be tested. Conduct tests to obtain a wider range of relevant basic data.

4. The present invention adopts a gas chromatograph and calibrates with equilibrium hydrogen to measure the ortho-parahydrogen concentration after the reaction, thereby obtaining the ortho-parahydrogen catalytic conversion data under different working conditions.

Description of drawings

Fig. 1 is a kind of overall structure schematic diagram of the hydrogen flow heat transfer and catalytic conversion test platform that utilizes low-temperature helium as a cold source in the present invention;

Fig. 2 is a schematic structural diagram of a heat exchange test unit in an embodiment of the present invention.

In the figure: 1-high-pressure hydrogen cylinder, 2-high-pressure nitrogen cylinder, 3-vacuum pump, 4-first-stage regenerator, 5-liquid nitrogen bath pre-reformer, 6-secondary regenerator, 7-ortho-parahydrogen catalysis Coil, 8-heat exchange test unit, 9-helium refrigeration unit, 10-reheater, 11-gas chromatograph, 12-hydrogen flowmeter, 13-helium flowmeter, 14-hydrogen flow regulating valve, 15- Helium flow regulating valve, 16-concentration bypass valve, 17-low temperature Dewar, 18-temperature bypass valve, 19-flow channel, 20-head, 21-angle aluminum, 22-hydrogen inlet, 23-hydrogen outlet , 24-helium inlet, 25-helium outlet, 26-catalyst filling inlet.

Detailed ways

The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be noted that the following embodiments are intended to facilitate the understanding of the present invention, but do not limit it in any way.

In order to achieve the experimental working conditions in the range from the liquid hydrogen temperature zone to the liquid nitrogen temperature zone, the present invention obtains relevant data on flow heat transfer and catalytic conversion performance of hydrogen at low temperature, and provides reference for industrial design, and designs a low-temperature helium gas As a cold source hydrogen heat exchange flow and conversion test platform, the test platform can realize a variety of working condition parameters including fluid parameters such as different fluid temperatures, pressures, and flow rates, and catalyst characteristic parameters such as different catalyst filling methods and porosity. And structural parameters such as the fin type and flow channel size of the plate-fin heat exchanger. Through this test platform, a series of basic data such as temperature distribution, pressure drop, catalyst dosage, and parahydrogen concentration under different working conditions can be obtained.

As shown in Figure 1, a hydrogen flow heat transfer and catalytic conversion test platform using low-temperature helium as a cold source, including a gas distribution system, a primary regenerator 4, a liquid nitrogen bath pre-reformer 5, and a secondary regenerator device 6, helium refrigeration unit 9, reheater 10 and gas chromatograph 11.

The gas distribution system includes a high-pressure hydrogen cylinder 1, a high-pressure nitrogen cylinder 2 and a vacuum pump 3. The hydrogen cylinder 1 controls the pressure through a safety valve and passes through a hydrogen flow meter 12 and a hydrogen flow regulating valve 14. After that, there are two branches, one of which flows through the reheating The device 10 is connected with the first-stage regenerator 4, and the other one flows into the liquid nitrogen bath pre-reformer 5 through the concentration bypass valve 16, and merges with the hydrogen gas flowing through the positive-parahydrogen catalytic coil 7; the high-pressure nitrogen cylinder 2 is located at Bypass the branch and connect the vacuum pump 3.

The hot fluid side of the primary regenerator 4 is connected to the high-pressure hydrogen cylinder 1 and the liquid nitrogen bath pre-reformer 5, and at the same time, the low-temperature hydrogen from the secondary regenerator 6 is recovered as a cold fluid.

The liquid nitrogen bath pre-reformer 5 includes an ortho-parahydrogen catalytic coil 7, which is placed in the liquid nitrogen bath, and the nitrogen gas generated by evaporation is evacuated by the pressure release of the pipeline.

The hot fluid side of the secondary regenerator 6 is connected to the liquid nitrogen bath pre-reformer 5 and the heat exchange test unit 8 , and the heat exchange test unit 8 is connected to the primary regenerator 4 on the cold fluid side.

The cold fluid side of the heat exchange test unit 8 is connected to the helium refrigeration unit 9; the hot fluid inlet of the heat exchange test unit 8 is connected to the secondary regenerator 6, and the hot fluid outlet is divided into two streams, which respectively enter the secondary regenerator 6 and reheat Device 10 acts as a cold fluid.

The hot fluid side of the reheater 10 is connected to the hydrogen from the hydrogen flow regulating valve 14 and the primary regenerator 4 , and the cold fluid side is connected to the heat exchange test unit 8 and the temperature bypass valve 18 .

The helium refrigeration unit 9 is a closed cycle, which provides cold fluid for the heat exchange test unit 8 and is connected with a helium flow meter 13 and a helium flow regulating valve 15 .

The primary regenerator 4, the liquid nitrogen bath pre-reformer 5, the secondary regenerator 6, the heat exchange test unit 8, and the reheater 10 are all placed in the low-temperature Dewar 17 and subjected to vacuum insulation treatment.

The gas chromatograph 11 is connected to the hydrogen exhaust pipeline at the outlet of the cold fluid side of the primary regenerator 4 and the hydrogen confluence pipeline at the end of the liquid nitrogen bath pre-reformer 5, and uses the standard hydrogen in the high-pressure hydrogen cylinder 1 as the carrier gas , to measure the concentration of ortho-parahydrogen in the hydrogen evacuation pipeline and the hydrogen confluence pipeline.

In the embodiment of the present invention, the primary regenerator 4 , the secondary regenerator 6 and the reheater 10 all adopt spiral tube heat exchangers.

The heat exchange test unit 8 is filled with an ortho-parahydrogen conversion catalyst in the flow channel on the side of the hot fluid, in which hydrogen undergoes flow heat exchange process accompanied by catalytic conversion. There are temperature measurement points on the outer wall of the heat exchange test unit 8 and the fluid partition wall, and the temperature of the wall is measured to convert the temperature distribution of the fluid.

The ortho-parahydrogen catalysis coil 7 is filled with an ortho-parahydrogen conversion catalyst, and the ortho-parahydrogen catalysis coil 7 is completely submerged in liquid nitrogen, and its side wall is fixed in the liquid nitrogen bath pre-converter 5 by a side pull structure. The liquid nitrogen bath pre-reformer 5 adopts multi-layer heat insulation, and the nitrogen gas generated by evaporation is discharged from the nitrogen pressure relief pipe.

The low-temperature Dewar 17 is vacuumed to maintain the low-temperature environment in the Dewar, and the Dewar end cover and the shell are connected by bolts. The first-stage regenerator 4, the liquid nitrogen bath pre-reformer 5, the second-stage regenerator 6, and the heat exchange test unit 8 are all welded to the Dewar end cover through the supporting structure, and can be detached as a whole.

As shown in Figure 2, the heat exchange test unit 8 is composed of a flow channel 19, a head 20 and an angle aluminum 21, and the angle aluminum 21 on the side plate is fixed as a supporting structure, including a hydrogen inlet 22, a hydrogen outlet 23, a helium inlet 24. The helium gas outlet 25 can be replaced by connecting with the pipeline through the VCR interface, testing samples of different structures, and the type and structure of the heat exchanger are not limited. The hydrogen inlet 22 pipeline in the heat exchange test unit 8 is provided with a branch, the bent branch is used as the hydrogen inlet, and the straight pipeline is used as the catalyst filling inlet 26 .

The working process of the present invention will be introduced below by taking a specific test as an example.

The nitrogen communication pipeline from the high-pressure nitrogen cylinder 2 is used to purge the entire test platform pipeline to remove the air in the pipeline, and then the pipeline is connected to the vacuum pump 3 for vacuuming to avoid hydrogen doping with impurity gases.

The helium refrigeration unit 9 is turned on, and the cold helium gas of 2.5g/s is cooled by the three-stage G-M refrigerator and flows into the heat exchange test unit 8 to pre-cool the heat exchange test unit 8 and the helium circulation pipeline; The liquid nitrogen input liquid nitrogen bath preconverter 5, it is precooled.

After the pre-cooling is completed, 300K, 2.5MPa hydrogen from the high-pressure hydrogen cylinder 1 is introduced into the pipeline and divided into two streams, one of which flows through the primary regenerator 4 and the liquid nitrogen bath pre-reformer 5 for pre-cooling. Conversion, another stream passes through the concentration bypass valve 16, no pre-conversion occurs, and rejoins with the pre-reformed hydrogen at the end of the liquid nitrogen bath pre-reformer 5 to obtain between standard hydrogen (normal-parahydrogen concentration ratio 3: 1) and the specific concentration between the corresponding equilibrium concentration. The hydrogen of this concentration reaches below the liquid nitrogen temperature (78K) after entering the secondary regenerator 6. Adjusted so that the hydrogen gas with a specific temperature and concentration enters the heat exchange test unit 8 to exchange heat with the cold fluid helium.

Among them, the flow channel in the heat exchange test unit 8 adopts a plate-fin heat exchanger, and the ortho-parahydrogen conversion catalyst is filled in the flow channel 19 and the head 20 through the catalyst filling inlet 26, and there are temperature measuring points inside the heat exchange test unit 8 , hydrogen in the heat exchange test unit 8 is accompanied by the ortho-parahydrogen conversion of the flow heat exchange process, the temperature distribution in the heat exchange flow process can be obtained, and the ortho-parahydrogen concentration measurement and the pressure are carried out at the outlet of the heat exchange test unit 8 Measurement; the concentration and temperature of the hydrogen inlet of the heat exchange test unit 8 can be adjusted through the concentration bypass valve 16 and the temperature bypass valve 18, and the hydrogen flow rate can be adjusted through the hydrogen flow regulating valve 14 to change the flow rate of the thermal fluid in the heat exchange test unit 8 and heat load, and the cold fluid side can adjust the helium flow through the helium flow regulating valve 15, thereby changing the cooling capacity provided in the helium refrigeration unit 9, and can obtain different cold source temperatures; based on the temperature of the hot fluid side, The flow, concentration adjustment and cooling capacity adjustment on the cold fluid side can obtain different working conditions of the heat exchange test unit 8, measure the heat exchange flow and conversion basic data under different working conditions, and further improve the heat exchange test unit. Thermal, flow and conversion properties are analyzed and evaluated.

On the other hand, through the VCR interface and the detachable support structure, the heat exchange test unit 8 can be replaced, so the present invention can test heat exchange test units with different flow channel sizes or structure types and obtain extensive relevant data, and Based on this, various working conditions and various heat exchange structures are analyzed and evaluated to provide data support and reference for the design of heat exchangers in hydrogen liquefaction systems.

The embodiments described above have described the technical solutions and beneficial effects of the present invention in detail. It should be understood that the above descriptions are only specific embodiments of the present invention, and are not intended to limit the present invention. All within the scope of the principles of the present invention Any modifications, supplements and equivalent replacements should be included within the protection scope of the present invention.

Claims (9)

1. A hydrogen flow heat transfer and catalytic conversion test platform using low temperature helium as a cold source for testing a heat exchange test unit (8), comprising: the device comprises a gas distribution system, a first-stage heat regenerator (4), a liquid nitrogen bath pre-converter (5), a second-stage heat regenerator (6), a helium refrigerating unit (9), a heat re-heater (10) and a gas chromatograph (11);

the gas distribution system comprises a high-pressure hydrogen cylinder (1), a high-pressure nitrogen cylinder (2) and a vacuum pump (3), wherein the high-pressure nitrogen cylinder (2) is positioned on a bypass branch of an output pipeline of the high-pressure hydrogen cylinder (1) and is connected with the vacuum pump (3);

the high-pressure hydrogen cylinder (1) is sequentially connected in series with a hydrogen flowmeter (12) and a hydrogen flow regulating valve (14) and then is divided into two branches, wherein one branch sequentially flows through a hot fluid side of the temperature re-heater (10), a hot fluid side of the first-stage heat regenerator (4) and a normal secondary hydrogen catalytic coil (7) in the liquid nitrogen bath pre-converter (5); the other branch flows through a concentration bypass valve (16) and then enters a liquid nitrogen bath pre-converter (5) and is combined with hydrogen flowing through a normal para-hydrogen catalytic coil (7);

the converged hydrogen sequentially flows through the hot fluid side of the secondary heat regenerator (6) and the hot fluid side of the heat exchange test unit (8) and then is divided into two paths, wherein one path sequentially flows through the cold fluid side of the heat regenerator (10) and the temperature bypass valve (18), and the other path sequentially flows through the cold fluid sides of the secondary heat regenerator (6) and the primary heat regenerator (4);

the heat exchange test unit (8) is filled with a positive-secondary hydrogen conversion catalyst in a runner at the side of the hot fluid, and hydrogen generates a flow heat exchange process accompanied with catalytic conversion in the runner; the cold fluid side of the heat exchange test unit (8) is connected with the helium refrigerating unit (9), and the helium refrigerating unit (9) is in closed circulation and provides cold fluid for the heat exchange test unit (8);

the gas chromatograph (11) is connected with a hydrogen evacuation pipeline of a cold fluid side outlet of the first-stage heat regenerator (4) and a hydrogen merging pipeline at the tail end of the liquid nitrogen bath pre-converter (5), and standard hydrogen in a high-pressure hydrogen cylinder (1) is used as carrier gas to measure the concentration of normal para-hydrogen in the hydrogen evacuation pipeline and the hydrogen merging pipeline.

2. The hydrogen flow heat transfer and catalytic conversion test platform using low-temperature helium as a cold source according to claim 1, wherein the primary heat regenerator (4), the liquid nitrogen bath pre-converter (5), the secondary heat regenerator (6), the heat exchange test unit (8) and the heat regenerator (10) are all placed in a low-temperature Dewar (17) and subjected to vacuum heat insulation treatment.

3. The hydrogen flow heat transfer and catalytic conversion testing platform using low-temperature helium as a cold source according to claim 1, wherein the primary heat regenerator (4), the secondary heat regenerator (6) and the heat regenerator (10) are all spiral tube type heat exchangers.

4. The hydrogen flow heat transfer and catalytic conversion testing platform using cryogenic helium as a cold source according to claim 1, wherein the heat exchange testing unit (8) comprises a hydrogen inlet (22), a hydrogen outlet (23), a helium inlet (24) and a helium outlet (25), each inlet and outlet is provided with a VCR interface for connection with a pipeline; wherein, the connecting pipeline of the hydrogen inlet (22) is provided with a branch circuit which is used as a catalyst filling inlet (26).

5. The hydrogen flow heat transfer and catalytic conversion test platform using cryogenic helium as a cold source according to claim 1, characterized in that hydrogen from the high pressure hydrogen cylinder (1) is split into two branches at room temperature, the flow of which is regulated by a concentration bypass valve (16) at room temperature and remixed at the end of the liquid nitrogen bath pre-converter (5);

the concentration of the hydrogen inlet (22) on the heat exchange test unit (8) is adjusted by adjusting the concentration bypass valve (16) to adjust the flow of the hydrogen entering the liquid nitrogen bath pre-converter (5) for pre-conversion.

6. The hydrogen flow heat transfer and catalytic conversion test platform using low-temperature helium as a cold source according to claim 1, wherein the low-temperature hydrogen at a hydrogen outlet (23) on the heat exchange test unit (8) is divided into two paths, one path returns to the secondary regenerator (6) as cold fluid to recover the cold energy, and the other path is rewuped by the rewriter (10) and then is emptied by the temperature bypass valve (18);

the temperature of the hydrogen inlet (22) on the heat exchange test unit (8) is adjusted by adjusting the flow of hydrogen entering the primary heat regenerator (4) and the secondary heat regenerator (6) as cold fluid through a temperature bypass valve (18) at room temperature.

7. The hydrogen flow heat transfer and catalytic conversion testing platform using low-temperature helium as a cold source according to claim 1, wherein temperature measuring points are arranged on the outer wall of the heat exchange testing unit (8) and the fluid partition wall and used for measuring the wall temperature so as to calculate the fluid temperature distribution.

8. The hydrogen flow heat transfer and catalytic conversion test platform using low-temperature helium as a cold source according to claim 1, wherein the normal-para-hydrogen catalytic coil (7) is completely immersed in liquid nitrogen in the liquid nitrogen bath pre-converter (5), and the normal-para-hydrogen catalytic coil (7) is internally filled with a normal-para-hydrogen conversion catalyst.

9. The hydrogen flow heat transfer and catalytic conversion testing platform using cryogenic helium as a cold source according to claim 1, wherein the liquid nitrogen bath pre-converter (5) adopts multi-layer insulation and discharges nitrogen generated by evaporation through a nitrogen pressure relief pipe.

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