Vehicle-mounted ammonia gas catalytic cracking hydrogen production device, control method and vehicle system

Abstract

The application provides a vehicle-mounted ammonia gas catalytic cracking hydrogen production device, a control method and a vehicle system. The device comprises an ammonia fuel tank and a hydrogen fuel tank for providing ammonia gas and hydrogen gas for an engine, an electronic control unit, an exhaust branch pipe arranged on an exhaust pipe of the engine and an ammonia cracking separation assembly installed in the exhaust branch pipe. The ammonia cracking separation assembly comprises a shell, a hydrogen filter and a spiral flow guide plate. The spiral flow guide plate is located between the hydrogen filter and the shell, the inner side of the spiral flow guide plate is tightly attached to the outer wall of the hydrogen filter, adjacent spiral flow guide plates form spiral flow channels, and the spiral flow guide plate is attached with a Cs / Ru-based catalyst. The application utilizes the spiral structure to increase the contact area and contact time of ammonia gas and the catalyst attached to the wall surface. More ammonia gas can be in contact with the catalyst to cause ammonia cracking reaction, the utilization rate of ammonia gas is improved, and the catalytic cracking efficiency of ammonia gas is greatly improved.

Description

Technical Field

[0001] This invention relates to a hydrogen production device, specifically an on-board ammonia catalytic cracking hydrogen production device, a control method, and a vehicle system. Background Technology

[0002] Hydrogen energy, as a clean and efficient energy source, is considered one of the important alternative energy options for the future. Compared to traditional gasoline-powered vehicles and lithium-ion electric vehicles, hydrogen fuel cell vehicles, which use hydrogen as fuel, have advantages such as zero emissions, high energy efficiency, long driving range, and strong load capacity, thus showing broad application prospects in the transportation sector. However, there are currently technical challenges in the production and storage of hydrogen for hydrogen fuel cell vehicles.

[0003] Liquid ammonia, a hydrogen-rich substance with a hydrogen mass fraction of 17.6%, readily transforms into a liquid state under normal temperature and pressure of 0.86 MPa or at normal pressure and low temperature of 240 K, thus facilitating storage and transportation. Simultaneously, ammonia can be cracked into hydrogen under high temperature and catalytic conditions, making it an important source of hydrogen energy for hydrogen fuel cell vehicles. Due to the widespread adoption of ammonia cracking hydrogen production technology, the produced hydrogen purity reaches 99.99%, meeting the requirements of hydrogen fuel cell vehicles. Therefore, ammonia cracking hydrogen production technology is a potential hydrogen supply route, although it is still in the theoretical research stage both domestically and internationally. Currently, most ammonia cracking hydrogen production devices choose to carry out the ammonia cracking reaction in a direct-flow channel. The ammonia gas introduced into the direct-flow channel briefly contacts the catalyst attached to the channel surface and cracks into hydrogen and nitrogen. Then, a hydrogen recovery device is used to recover and reuse the hydrogen from the ammonia-hydrogen-nitrogen mixture. However, this direct-flow channel structure has the problem of a small contact area and short contact time between ammonia and catalyst. In addition, a large amount of internal gas flow cannot contact the catalyst attached to the channel surface and is directly discharged. This makes the utilization rate of ammonia and the ammonia cracking efficiency low, and the amount of hydrogen produced is difficult to meet the needs of actual working conditions. Summary of the Invention

[0004] To address the problems of low ammonia utilization and separation efficiency in current ammonia cracking hydrogen production devices, this invention provides an on-board ammonia catalytic cracking hydrogen production device, control method, and vehicle system. This device abandons the traditional direct-flow channel structure and adopts a spiral channel structure. The spiral structure increases the contact area and contact time between ammonia and the catalyst attached to the wall surface. This not only allows more ammonia to contact the catalyst and undergo the ammonia cracking reaction, thus improving ammonia utilization, but also significantly improves the catalytic cracking efficiency of ammonia and the amount of hydrogen produced.

[0005] The present invention achieves the above-mentioned technical objectives through the following technical means.

[0006] A vehicle-mounted ammonia catalytic cracking hydrogen production device is characterized by comprising an ammonia fuel tank and a hydrogen fuel tank for supplying ammonia and hydrogen to an engine, an electronic control unit, an exhaust branch pipe installed on the engine exhaust pipe, and an ammonia cracking separation assembly installed in the exhaust branch pipe. The ammonia cracking separation assembly includes a housing, a hydrogen filter, and a spiral guide plate. An inlet and an outlet are respectively provided at both ends of the housing. The inlet is connected to the ammonia fuel tank via pipe a, and the outlet is connected to the exhaust branch pipe. The hydrogen filter is coaxially fixed inside the housing, and its outlet is connected to the hydrogen fuel tank via pipe b. The outlet of the hydrogen filter passes through the outlet and has a gap between it and the outlet. The spiral guide plate is located between the hydrogen filter and the housing, and the inner side of the spiral guide plate is flush with the inner side of the hydrogen filter. The outer walls are tightly fitted, and a spiral flow channel connecting the inlet and outlet is formed between adjacent spiral guide plates; a Cs / Ru-based catalyst is attached to the spiral guide plates; a first solenoid valve for controlling ammonia flow is installed on pipe a, and a second solenoid valve for controlling tail gas flow is installed on the exhaust branch pipe; a temperature sensor is installed inside the ammonia cracking separation assembly to collect the internal temperature of the ammonia cracking separation assembly; a flow sensor for detecting hydrogen flow is installed on pipe b; the first solenoid valve, the second solenoid valve, the temperature sensor, and the flow sensor are all connected to an electronic control unit, which adjusts the opening and closing and the degree of opening of the first and second solenoid valves according to the internal temperature of the ammonia cracking separation assembly detected by the temperature sensor and the hydrogen flow detected by the flow sensor;

[0007] The hydrogen filter has a cylindrical structure, including an outer cage and an inner cage nested together, end caps fixed at both ends of the outer cage and the inner cage, and a Pd / Ni alloy filter membrane sandwiched between the outer cage and the inner cage. The Pd / Ni alloy filter membrane and the end caps on both sides isolate the filtered hydrogen from the outside gas, allowing it to flow along pipe b to the hydrogen fuel tank.

[0008] Furthermore, the outer diameter edge of the spiral guide plate is inclined towards the air inlet, and the angle between the cross section of the spiral guide plate and the radial cross section of the ammonia cracking separation component is 10-30°.

[0009] Furthermore, an ammonia pressure stabilizing tank is installed on pipeline a between the first solenoid valve and the ammonia fuel tank.

[0010] Furthermore, a one-way valve is provided on the pipe b.

[0011] Furthermore, the molar ratio of Cs to Ru in the Cs / Ru-based catalyst is 3:1.

[0012] Furthermore, the exhaust branch pipe is connected in parallel with the exhaust pipe between the engine's exhaust port and the SCR exhaust treatment system.

[0013] Furthermore, a nitrogen-hydrogen separator is provided on pipe b downstream of the flow sensor. The hydrogen output end of the nitrogen-hydrogen separator is connected to the downstream pipe b, and the nitrogen output end is connected to the exhaust branch pipe downstream of the ammonia cracking separation component.

[0014] The control method for the on-board ammonia catalytic cracking hydrogen production device described in any one of the above-mentioned methods is characterized by comprising the following steps:

[0015] S1: Open the second solenoid valve, and the engine exhaust gas enters the exhaust manifold.

[0016] S2: The temperature inside the ammonia cracking separation component is collected by a temperature sensor. When the temperature inside the ammonia cracking separation component reaches 450~570K, the first solenoid valve is opened to introduce ammonia into the ammonia cracking separation component, and the hydrogen produced by ammonia cracking is recovered through a hydrogen filter.

[0017] S3: During the ammonia cracking separation process, the flow rate of hydrogen in the exhaust pipe is monitored in real time by a flow sensor, and the opening of the first solenoid valve is adjusted according to the hydrogen flow rate to control the amount of ammonia introduced, so that the ammonia cracking reaction is kept in a stable state. At the same time, the internal temperature of the ammonia cracking separation component is monitored in real time. When the internal temperature of the ammonia cracking separation component exceeds 570K, the opening of the second solenoid valve is reduced or closed to reduce the amount of tail gas introduced; when the internal temperature of the ammonia cracking separation component is below 450K, the opening of the second solenoid valve is increased to increase the amount of tail gas introduced, so that the internal temperature of the ammonia cracking separation component is maintained within the range of 450~570K.

[0018] A vehicle system, characterized in that it includes an on-board ammonia catalytic cracking hydrogen production device as described in any one of the above claims.

[0019] The beneficial effects of this invention are as follows:

[0020] 1. The spiral flow channel design in this invention allows ammonia gas to continuously rotate and advance within the pipe. Compared with the traditional direct flow channel, the flow path of ammonia gas in the spiral flow channel is longer, which increases the contact area and contact time between ammonia gas and the Cs / Ru-based catalyst attached to the wall surface. Ammonia gas has more opportunities to react with the catalyst, thereby improving the utilization rate of ammonia gas and the catalytic cracking rate.

[0021] 2. In this invention, the cross-section of the spiral guide plate forms a certain angle with the radial cross-section of the ammonia cracking separation component. When ammonia comes into contact with the spiral guide plate, under the guiding effect of the inclined structure, the ammonia gathers towards the ammonia cracking separation component inside the spiral guide plate, thereby increasing the filtration efficiency of hydrogen.

[0022] 3. Traditional Ru-based catalysts have reaction temperatures greater than 500℃ and reaction pressures greater than 10MPa. In contrast, this invention uses a Cs / Ru-based catalyst to catalyze the ammonia cracking reaction. The promoter Cs in the Cs / Ru-based catalyst can electronically modify Ru, reducing the activation energy of the catalytic reaction. This allows the catalyst to maintain high catalytic activity even at low temperatures and low pressures of 200℃ and 3MPa, thereby increasing the ammonia conversion rate at low temperatures and low pressures. This significantly broadens the application range compared to traditional Ru-based catalysts.

[0023] 4. Since the temperature of automobile exhaust is generally above 300°C, the waste heat of the exhaust can be used to reach the optimal catalytic reaction temperature of the Cs / Ru-based catalyst in this invention. That is, the low-temperature catalytic activity of the Cs / Ru-based catalyst provides a prerequisite for the ammonia cracking separation component to be installed in the engine exhaust pipe for heating, which is conducive to the integrated and miniaturized installation of the ammonia cracking device in hydrogen fuel cell vehicles, while improving energy utilization. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the vehicle-mounted ammonia catalytic cracking hydrogen production device described in Embodiment 1 of the present invention;

[0025] Figure 2 This is a cross-sectional view of the ammonia cracking separation assembly described in Embodiment 1 of the present invention;

[0026] Figure 3 for Figure 2 A magnified view of a section at point A in the middle;

[0027] Figure 4 This is a schematic diagram of the flow sensor described in Embodiment 1 of the present invention;

[0028] Figure 5 This is a schematic diagram of the vehicle-mounted ammonia catalytic cracking hydrogen production device described in Embodiment 2 of the present invention.

[0029] The attached figures are labeled as follows:

[0030] 1-Ammonia fuel tank; 2-Hydrogen fuel tank; 3-Electronic control unit; 4-Exhaust branch pipe; 5-Outer casing; 6-Spiral guide plate; 7-Pipe a; 8-Inlet; 9-Outlet; 10-Spiral flow channel; 11-Pipe b; 12-First solenoid valve; 13-Second solenoid valve; 14-Temperature sensor; 15-Flow sensor; 16-Ammonia pressure stabilizing tank; 17-End cap; 18-Outer cage; 19-Inner cage; 20-Pd / Ni alloy filter membrane; 21-Exhaust pipe; 22-SCR exhaust gas treatment system; 23-Nitrogen-hydrogen separator; 24-Engine. Detailed Implementation

[0031] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but the scope of protection of the present invention is not limited thereto.

[0032] Example 1

[0033] The on-board ammonia catalytic cracking hydrogen production device described in this embodiment includes an ammonia fuel tank 1 and a hydrogen fuel tank 2 that supply ammonia and hydrogen to the engine 24, an electronic control unit 3, an exhaust branch pipe 4 installed on the exhaust pipe 21 of the engine 24, and an ammonia cracking separation assembly installed in the exhaust branch pipe 4. Figure 1 This is a schematic diagram of the on-board ammonia catalytic cracking hydrogen production device described in this embodiment.

[0034] The ammonia cracking separation assembly includes a housing 5, a hydrogen filter, and a spiral guide plate 6. The housing 5 has an inlet 8 and an outlet 9 at both ends. The inlet 8 is connected to the ammonia fuel tank 1 via pipe a7, and the outlet 9 is connected to the exhaust branch pipe 4. The hydrogen filter is coaxially fixed inside the housing 5, and its outlet is connected to the hydrogen fuel tank 2 via pipe b11, which is equipped with a one-way valve. The outlet of the hydrogen filter passes through the outlet 9, leaving a gap between them. The spiral guide plate 6 is located between the hydrogen filter and the housing 5. The inner side of the spiral guide plate 6 is tightly fitted to the outer wall of the hydrogen filter, and adjacent spiral guide plates 6 form a spiral flow channel 10 connecting the inlet 8 and the outlet 9. The outer diameter edge of the spiral guide plate 6 is inclined towards the inlet 8, and the angle α between the cross-section of the spiral guide plate 6 and the radial cross-section of the ammonia cracking separation assembly is 20°. A Cs / Ru-based catalyst is attached to the spiral guide plate 6. Figure 2 This is a cross-sectional view of the ammonia cracking separation assembly described in this embodiment.

[0035] The hydrogen filter has a cylindrical structure, including an outer cage 18 and an inner cage 19 nested together, end caps 17 fixed at both ends of the outer cage 18 and the inner cage 19, and a Pd / Ni alloy filter membrane 20 sandwiched between the outer cage 18 and the inner cage 19. The Pd / Ni alloy filter membrane 20 and the end caps 17 isolate the filtered hydrogen from the outside gas, allowing it to flow along the pipe b11 to the hydrogen fuel tank 2. Figure 3 This is a partially enlarged view of the hydrogen filter described in this embodiment.

[0036] A first solenoid valve 12 for controlling ammonia flow is installed on pipe a7. An ammonia pressure stabilizing tank 16 is installed on pipe a7 between the first solenoid valve 12 and the ammonia fuel tank 1 to supply ammonia gas at approximately 3 MPa to the ammonia cracking separation assembly, ensuring that the gas pressure inside the outer casing 5 meets the optimal reaction pressure value for the Cs / Ru-based catalyst. A second solenoid valve 13 for controlling tail gas flow is installed on the exhaust branch pipe 4. A temperature sensor 14 is installed inside the ammonia cracking separation assembly to collect the internal temperature. A Karman vortex gas flow sensor for detecting hydrogen flow is installed on pipe b11. Figure 4 This is a schematic diagram of a Karman vortex gas flow sensor, including a rectifier grid and a gas flow sensor. The gas flow sensor contains a vortex generator. The Karman vortex gas flow sensor uses the rectifier grid to rectify the hydrogen gas in the pipeline. After rectification, the hydrogen gas flows through the vortex generator, continuously generating a series of asymmetrical but highly regular Karman vortices. The gas flow sensor calculates the hydrogen flow rate by measuring the number of vortices per unit time. The first solenoid valve 12, the second solenoid valve 13, the temperature sensor 14, and the Karman vortex gas flow sensor are all connected to the electronic control unit 3. The electronic control unit 3 regulates the opening and closing of the first solenoid valve 12 and the opening degree of the second solenoid valve 13 based on the temperature inside the ammonia cracking separation component detected by the temperature sensor 14 and the hydrogen flow rate detected by the Karman vortex gas flow sensor.

[0037] Furthermore, the exhaust branch pipe 4 is connected in parallel with the exhaust pipe 21 between the exhaust port of the engine 24 and the SCR exhaust gas treatment system 22.

[0038] In this embodiment, the molar ratio of Cs to Ru in the Cs / Ru-based catalyst is 3:1. The promoter Cs can electronically modify Ru, reducing the activation energy of the catalytic reaction. As the Cs content in the Cs / Ru-based catalyst increases, its low-temperature activity is significantly improved. When the molar ratio of Cs to Ru is 3:1, the activation energy of the Cs / Ru-based catalyst is 59.3 kJ / mol. When the Cs content continues to increase, ammonia cannot approach the catalytic active site, thus affecting the catalytic effect.

[0039] The control method for the on-board ammonia catalytic cracking hydrogen production device described in this embodiment includes the following steps:

[0040] S1: Open the second solenoid valve 13, and the exhaust gas from the engine 24 enters the exhaust manifold 4.

[0041] S2: The temperature inside the ammonia cracking separation component is collected by the temperature sensor 14. When the temperature inside the ammonia cracking separation component reaches 450~570K, the first solenoid valve 12 is opened to introduce ammonia into the ammonia cracking separation component, and the hydrogen generated by ammonia cracking is recovered through the hydrogen filter.

[0042] S3: During the ammonia cracking separation process, the flow rate of hydrogen in the exhaust pipe 21 is monitored in real time by a Karman vortex gas flow sensor, and the opening of the first solenoid valve 12 is adjusted according to the hydrogen flow rate to control the amount of ammonia introduced, so that the ammonia cracking reaction is kept in a stable state. At the same time, the internal temperature of the ammonia cracking separation component is monitored in real time. When the internal temperature of the ammonia cracking separation component exceeds 570K, the opening of the second solenoid valve 13 is reduced or closed to reduce the amount of tail gas introduced. When the internal temperature of the ammonia cracking separation component is lower than 450K, the opening of the second solenoid valve 13 is increased to increase the amount of tail gas introduced, so that the internal temperature of the ammonia cracking separation component is maintained in the range of 450~570K.

[0043] This embodiment also relates to a vehicle system equipped with the above-mentioned on-board ammonia catalytic cracking hydrogen production device.

[0044] Example 2

[0045] The difference between this embodiment and Embodiment 1 is that a nitrogen-hydrogen separator 23 is installed on the pipe b11 downstream of the flow sensor 15. The hydrogen output end of the nitrogen-hydrogen separator 23 is connected to the downstream pipe b11, and the nitrogen output end is connected to the exhaust branch pipe 4 downstream of the ammonia cracking separation assembly. The nitrogen-hydrogen separator 23 uses a nitrogen-hydrogen separation membrane to separate hydrogen and a small amount of nitrogen in the pipe b11. The purified hydrogen enters the hydrogen fuel tank 2 as the hydrogen fuel source for the engine. Figure 5 This is a schematic diagram of the on-board ammonia catalytic cracking hydrogen production device described in this embodiment.

[0046] The embodiments described above are preferred embodiments of the present invention, but the present invention is not limited to the above embodiments. Any obvious improvements, substitutions or modifications that can be made by those skilled in the art without departing from the essence of the present invention shall fall within the protection scope of the present invention.

Claims

1. A vehicle-mounted ammonia catalytic cracking hydrogen production device, characterized in that, Includes an ammonia fuel tank (1) and a hydrogen fuel tank (2) that supply ammonia and hydrogen to the engine (24), an electronic control unit (3), an exhaust branch pipe (4) installed on the exhaust pipe (21) of the engine (24), and an ammonia cracking and separation assembly installed in the exhaust branch pipe (4); The ammonia cracking separation assembly includes a shell (5), a hydrogen filter, and a spiral guide plate (6). An inlet (8) and an outlet (9) are respectively provided at both ends of the shell (5). The inlet (8) is connected to the ammonia fuel tank (1) through pipe a (7), and the outlet (9) is connected to the exhaust branch pipe (4). The hydrogen filter is coaxially fixed inside the shell (5). The outlet of the hydrogen filter is connected to the hydrogen fuel tank (2) through pipe b (11). The outlet of the hydrogen filter passes through the outlet (9) and leaves a gap between it and the outlet (9). The spiral guide plate (6) is located between the hydrogen filter and the shell (5), and the inner side of the spiral guide plate (6) is tightly fitted to the outer wall of the hydrogen filter. A spiral flow channel (10) connecting the inlet (8) and the outlet (9) is formed between adjacent spiral guide plates (6). A Cs / Ru-based catalyst is attached to the spiral guide plate (6). The pipeline a (7) is equipped with a first solenoid valve (12) for controlling the flow of ammonia gas, and the exhaust branch pipe (4) is equipped with a second solenoid valve (13) for controlling the flow of tail gas. The ammonia cracking separation assembly is equipped with a temperature sensor (14) for collecting the temperature inside the ammonia cracking separation assembly. The pipeline b (11) is equipped with a flow sensor (15) for detecting the flow of hydrogen gas. The first solenoid valve (12), the second solenoid valve (13), the temperature sensor (14), and the flow sensor (15) are all connected to the electronic control unit (3). The electronic control unit (3) adjusts the opening and closing of the first solenoid valve (12) and the opening degree of the second solenoid valve (13) according to the temperature inside the ammonia cracking separation assembly detected by the temperature sensor (14) and the hydrogen flow rate detected by the flow sensor (15). The hydrogen filter is a cylindrical structure, including an outer cage (18) and an inner cage (19) nested together, end caps (17) fixed at both ends of the outer cage (18) and the inner cage (19), and a Pd / Ni alloy filter membrane (20) sandwiched between the outer cage (18) and the inner cage (19). The Pd / Ni alloy filter membrane (20) and the end caps (17) on both sides isolate the filtered hydrogen from the outside gas, allowing it to flow along the pipe b (11) to the hydrogen fuel tank (2).

2. The on-board ammonia catalytic cracking hydrogen production device according to claim 1, characterized in that, The outer diameter edge of the spiral guide plate (6) is inclined toward the air inlet (8), and the angle between the cross section of the spiral guide plate (6) and the radial cross section of the ammonia cracking separation component is 10-30°.

3. The on-board ammonia catalytic cracking hydrogen production device according to claim 1, characterized in that, An ammonia pressure stabilizing tank (16) is installed on the pipeline a (7) between the first solenoid valve (12) and the ammonia fuel tank (1).

4. The on-board ammonia catalytic cracking hydrogen production device according to claim 1, characterized in that, A one-way valve is provided on the pipe b (11).

5. The on-board ammonia catalytic cracking hydrogen production device according to claim 1, characterized in that, The molar ratio of Cs to Ru in the Cs / Ru-based catalyst is 3:

1.

6. The on-board ammonia catalytic cracking hydrogen production device according to claim 1, characterized in that, The exhaust branch pipe (4) and the exhaust pipe (21) are connected in parallel between the exhaust port of the engine (24) and the SCR exhaust treatment system (22).

7. The on-board ammonia catalytic cracking hydrogen production device according to claim 2, characterized in that, A nitrogen-hydrogen separator (23) is provided on the pipe b (11) downstream of the flow sensor (15). The hydrogen output end of the nitrogen-hydrogen separator (23) is connected to the downstream pipe b (11), and the nitrogen output end is connected to the exhaust branch pipe (4) downstream of the ammonia cracking separation component.

8. The control method for the vehicle-mounted ammonia catalytic cracking hydrogen production device according to any one of claims 1 to 7, characterized in that, Includes the following steps: S1: Open the second solenoid valve (13), and the exhaust gas of the engine (24) enters the exhaust manifold (4); S2: The temperature inside the ammonia cracking separation component is collected by the temperature sensor (14). When the temperature inside the ammonia cracking separation component reaches 450~570K, the first solenoid valve (12) is opened to introduce ammonia into the ammonia cracking separation component, and the hydrogen generated by ammonia cracking is recovered through the hydrogen filter. S3: During the ammonia cracking separation process, the flow rate of hydrogen in the exhaust pipe (21) is monitored in real time by the flow sensor (15), and the opening of the first solenoid valve (12) is adjusted according to the flow rate of hydrogen to control the amount of ammonia introduced, so that the ammonia cracking reaction is kept in a stable state; at the same time, the temperature inside the ammonia cracking separation component is monitored in real time. When the temperature inside the ammonia cracking separation component exceeds 570K, the opening of the second solenoid valve (13) is reduced or closed to reduce the amount of tail gas introduced; when the temperature inside the ammonia cracking separation component is lower than 450K, the opening of the second solenoid valve (13) is increased to increase the amount of tail gas introduced; so that the temperature inside the ammonia cracking separation component is maintained in the range of 450~570K.

9. A vehicle system, characterized in that, The device includes the vehicle-mounted ammonia catalytic cracking hydrogen production apparatus according to any one of claims 1 to 7.

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