Ammonia catalytic cracking hydrogen production device based on engine exhaust waste heat utilization, control system and control method

Abstract

The invention belongs to the field of ammonia cracking hydrogen production devices, and particularly relates to an ammonia catalytic cracking hydrogen production device based on engine exhaust waste heat utilization, a control system and a control method.The ammonia catalytic cracking hydrogen production device comprises an ammonia catalytic cracking hydrogen production system, a nitrogen-hydrogen separation system and a working condition control system; the ammonia catalytic cracking hydrogen production system comprises an exhaust pipe, and an ammonia gas cracking pipe and a heat insulation pipe which sequentially wrap the outer wall of the exhaust pipe; the ammonia gas cracking pipe comprises an ammonia gas inlet and a cracking mixed gas outlet, and a gap is reserved between the inner wall of the ammonia gas cracking pipe and the outer wall of the exhaust pipe and used for circulation and cracking of ammonia gas; the nitrogen-hydrogen separation system comprises a hydrogen separation unit, a nitrogen separation unit and an ammonia gas recovery unit; the cracking mixed gas outlet is connected with the hydrogen separation unit; the ammonia gas recovery unit comprises an ammonia water heating bin, and the exhaust pipe penetrates through the ammonia water heating bin. Ammonia gas cracking and nitrogen-hydrogen separation are completed by fully utilizing engine tail gas waste heat, the cost and energy consumption are remarkably reduced, and hydrogen supply for promoting efficient and reliable combustion of the ammonia engine can be obtained.

Description

Technical Field

[0001] The present invention belongs to the technical field of ammonia cracking hydrogen production devices, and more specifically relates to an ammonia catalytic cracking hydrogen production device based on engine exhaust waste heat utilization, a control system and a control method. Background Art

[0002] Global climate and environmental changes have posed severe challenges to human economic and social development. Low-carbonization and even zero-carbonization have become an inevitable trend in the development of the world economy, and low-carbon technology will become the new "engine" of global economic development. The essence of zero-carbon technology for internal combustion engines is to burn carbon-neutral fuels to achieve zero-carbon emissions throughout the life cycle. Studies have found that ammonia, as an efficient hydrogen storage medium, has the advantages of no carbon emissions, high energy density, mature manufacturing process, easy liquefaction, storage and transportation, and high safety.

[0003] Since ammonia fuel is difficult to ignite and has a slow combustion speed, it is difficult to be widely used in dynamic devices such as engines. Using a pre-combustion chamber to burn pure hydrogen to produce a high-intensity hydrogen flame jet to ignite the ammonia-air mixture can achieve stable ignition and rapid combustion of the ammonia-air mixture, thereby achieving reliable and efficient operation of dynamic devices such as ammonia engines. Therefore, how to prepare sufficient high-purity hydrogen for the ammonia engine in real time during operation to achieve stable ignition and rapid combustion of the ammonia engine is crucial to the promotion of ammonia engines. At the same time, it is of great significance to use exhaust waste heat to save energy to the greatest extent.

[0004] Patent CN102216588B discloses an ammonia engine system. The system first uses the waste heat of the engine exhaust (150°C) to provide heat to the ammonia oxidation device under low exhaust temperature, and then uses the heat generated by the ammonia oxidation reaction to crack ammonia, thereby meeting the demand for ammonia cracking under low-temperature exhaust. However, the system uses the oxidation reaction of the raw materials to release heat, which will waste a lot of fuel; at the same time, the system cannot obtain high-purity hydrogen.

[0005] Patent CN114893331A discloses a vehicle-mounted ammonia decomposition hydrogen production system, which includes an exhaust gas chamber that is "fishbone-shaped" as a whole and a cracking chamber with a matching inner wall. When ammonia passes through the cracking chamber with a baffle inside, it receives heat from the outer wall electric heating plate and the inner wall exhaust gas at the same time to complete catalytic decomposition. Although the device can efficiently utilize waste heat and improve the decomposition efficiency of ammonia, it lacks temperature monitoring and cannot adjust the catalytic temperature in real time, which poses a risk of igniting the internal gas. Moreover, the waste heat of the exhaust gas is not fully utilized, resulting in waste.

[0006] Patent CN117231388A discloses a vehicle-mounted ammonia catalytic cracking hydrogen production device, control method and vehicle system. The system arranges a spiral catalytic device on the exhaust pipe. Under the action of Cs / Ru-based catalysts, it can complete the catalytic cracking of ammonia at the exhaust gas temperature, and use the spiral guide plate structure to improve the hydrogen filtration efficiency. However, the device cannot achieve stable ignition under startup conditions and low-temperature conditions, and cannot achieve the expected hydrogen production efficiency under low conditions. Summary of the invention

[0007] The object of the present invention is to provide an ammonia catalytic cracking hydrogen production device, a control system and a control method based on the utilization of engine exhaust waste heat, so as to fully utilize the engine exhaust gas to complete ammonia cracking and nitrogen-hydrogen separation, and realize real-time preparation of high-purity hydrogen.

[0008] To achieve the above-mentioned object, the present invention provides an ammonia catalytic cracking hydrogen production device based on the utilization of engine exhaust waste heat, comprising an ammonia catalytic cracking hydrogen production system and a nitrogen-hydrogen separation system, wherein the ammonia catalytic cracking hydrogen production system comprises an exhaust pipe and an ammonia cracking pipe and an insulation pipe sequentially wrapped around the outer wall of the exhaust pipe; the ammonia cracking pipe comprises an ammonia inlet and a cracked mixed gas outlet, and a gap is left between the inner wall of the ammonia cracking pipe and the outer wall of the exhaust pipe for the circulation and cracking of ammonia; the exhaust pipe is used to discharge engine exhaust gas;

[0009] The nitrogen-hydrogen separation system comprises a hydrogen separation unit, a nitrogen separation unit and an ammonia recovery unit; the hydrogen separation unit is connected to the cracked mixed gas outlet; the ammonia recovery unit comprises an ammonia water heating chamber, and the exhaust pipe passes through the interior of the ammonia water heating chamber.

[0010] Furthermore, the outer wall of the exhaust pipe and the inner wall of the ammonia cracking pipe are provided with fins arranged at intervals to form a maze, which is used to increase the heat transfer area and extend the ammonia flow path.

[0011] Furthermore, the fin is a good conductor of heat and is mounted on two layers of metal mounting plates, the inner metal mounting plate is tightly mounted on the outer wall of the exhaust pipe, and the gap between the inner metal mounting plate and the exhaust pipe is filled with thermal conductive glue to increase the transfer of exhaust heat flow; the outer metal mounting plate is also mounted on the outside of the exhaust pipe, and the inner metal mounting plate is wrapped inside to form an ammonia channel; in order to increase the heat conduction of the outer metal mounting plate, the front and rear ends of the outer metal mounting plate are in close contact with the outer wall of the exhaust pipe to form a closed ammonia channel space, and at the same time, a heat conducting column is set in the fin area to increase the temperature of the outer fin and the ammonia cracking rate. Furthermore, along the ammonia flow path, an ammonia cracking catalyst is evenly coated on the surfaces of both sides of the fin, and the catalyst catalyzes the cracking of the ammonia.

[0012] Furthermore, the inner metal mounting plate may also be the outer wall of the exhaust pipe, without separately providing an inner metal mounting plate.

[0013] Furthermore, the ammonia flow channel is sealed by two layers of metal mounting plates inside and outside to prevent leakage and explosion of cracked hydrogen. Furthermore, before the engine is started, ammonia is introduced to purge air to prevent air from remaining in the ammonia flow channel.

[0014] Furthermore, a heating plate and an electrode connected to the heating plate are provided between the ammonia cracking tube and the insulation tube, so as to supplement heat for the cracking of the ammonia under low temperature conditions.

[0015] Furthermore, a temperature sensor is provided in the ammonia cracking tube, and the temperature sensor is used to monitor and adjust the temperature of the catalyst.

[0016] Furthermore, the heating plate is a high energy density heating plate, such as a quartz wire heating plate, and the heating plates are evenly distributed on the outer metal mounting plate.

[0017] Furthermore, the above method of increasing the fin temperature is mainly used to increase the thermal cracking efficiency and catalytic thermal cracking efficiency of ammonia.

[0018] Furthermore, the hydrogen separation unit comprises an air duct connected to the cracked mixed gas outlet, the air duct comprises a hydrogen outlet and a mixed gas outlet; the hydrogen outlet is provided with a hydrogen separation membrane for selective passage of hydrogen.

[0019] Furthermore, the volume at the hydrogen outlet is increased, the cracking gas flow rate is reduced, and the hydrogen leakage efficiency is improved.

[0020] Furthermore, the nitrogen separation unit includes a water bath, which is filled with water; the mixed gas outlet extends into the water of the water bath, the top of the water bath is provided with a nitrogen outlet, and the bottom is provided with an ammonia outlet. A water level control device is provided in the water bath to control the water level, such as a float, so that the circulating water does not fill the entire water bath, which is used for gas-water separation and nitrogen discharge.

[0021] Furthermore, a pressure cap is provided at the nitrogen outlet to slow down the gas flow rate and further promote the permeation efficiency of hydrogen.

[0022] Furthermore, the ammonia recovery unit includes an ammonia heating tank connected to the ammonia outlet, and an ammonia outlet is provided on the top of the ammonia heating tank. The ammonia in the ammonia heating tank is decomposed to release ammonia under the action of the waste heat of the engine exhaust gas in the exhaust pipe, and the ammonia is discharged from the ammonia outlet and returned to the ammonia recovery outlet.

[0023] Furthermore, the water bath tank and the ammonia water heating tank are connected by a circulating water pipe and a second spiral bent pipe, and a water pump is provided on the circulating water pipe; the water in the water bath tank dissolves ammonia and flows into the ammonia water heating tank, and after the ammonia escapes due to the heat, the remaining water is circulated through the second spiral bent pipe and introduced into the water bath tank.

[0024] Furthermore, the ammonia outlet is provided with a gas-water separator and a dryer for separating the water discharged along with the ammonia and drying the ammonia.

[0025] Furthermore, the portion of the exhaust pipe passing through the ammonia water heating chamber is configured as a first spirally bent pipe to increase the heat exchange area.

[0026] Furthermore, a temperature monitoring device is provided in the exhaust pipe, and an ammonia concentration monitoring device is provided in the ammonia cracking tube for operating condition control.

[0027] The present invention also provides a control system for an ammonia catalytic cracking hydrogen production device based on the utilization of engine exhaust waste heat as described in any of the above items, comprising a temperature monitoring unit, a temperature control unit, an ammonia concentration monitoring unit and an ammonia intake rate control unit; the temperature monitoring unit is used to monitor the catalytic cracking temperature in the ammonia cracking tube, and transmit the monitoring result to the temperature control unit, and the temperature control unit is used to control the temperature of the heating plate to adapt to the high-efficiency cracking requirements under different exhaust conditions; the ammonia concentration monitoring unit is used to monitor the concentration of ammonia in the ammonia cracking tube, and transmit the monitoring result to the ammonia intake rate control unit, and the ammonia intake rate control unit is used to control the ammonia intake rate to ensure the cracking efficiency of ammonia.

[0028] The present invention also provides a control method for an ammonia catalytic cracking hydrogen production device based on the utilization of engine exhaust waste heat as described in any one of the above, using the control system described above, comprising: introducing the engine exhaust gas from the exhaust inlet of the exhaust pipe in real time and leading it out from the exhaust outlet, while introducing ammonia from the ammonia inlet of an ammonia cracking tube equipped with a catalyst; separating and recovering hydrogen, nitrogen and ammonia through a hydrogen separation unit, a nitrogen separation unit and an ammonia recovery unit in sequence for the mixed gas generated by the cracking;

[0029] The catalytic cracking temperature in the ammonia cracking tube is monitored by the temperature monitoring unit, and the monitoring result is transmitted to the temperature control unit to control the temperature of the heating plate to adapt to different exhaust conditions; the ammonia concentration monitoring unit monitors the ammonia concentration in the ammonia cracking tube, and the monitoring result is transmitted to the ammonia intake rate control unit to control the ammonia intake rate.

[0030] In general, the above technical solution conceived by the present invention has the following technical advantages compared with the prior art:

[0031] 1. The device for producing hydrogen by catalytic cracking of ammonia based on the waste heat of engine exhaust provided by the present invention sequentially passes the exhaust pipe through which the engine exhaust gas passes through the catalytic cracking of ammonia to produce hydrogen system and the nitrogen-hydrogen separation system, firstly utilizes the high-temperature waste heat of the exhaust gas to promote the catalytic cracking of ammonia, and then utilizes the waste heat to promote the decomposition and recovery of ammonia, thereby realizing the real-time cracking of ammonia fuel to produce hydrogen, with low energy consumption, low pollution, good separation effect and high purity.

[0032] 2. The device combines the functions of catalytic cracking and high-temperature cracking, comprehensively uses catalysts and high exhaust temperatures, and adds bidirectional opposing fins to the ammonia cracking tube, dividing the ammonia channel into a maze shape, so that the catalytic system is heated evenly and the flow rate of ammonia fuel is slowed down, which can efficiently crack ammonia and does not require additional energy consumption under most operating conditions.

[0033] 3. After hydrogen is screened out by the hydrogen separation membrane, ammonia is easily soluble in water and its solubility changes significantly with temperature. After ammonia and nitrogen are separated by water, the exhaust waste heat is used to separate ammonia and water. This device can realize the closed loop of ammonia fuel, which is conducive to improving the safety and economy of the entire system.

[0034] 4. The device makes full use of exhaust energy, which can greatly improve the catalytic cracking efficiency, greatly reduce the volume of the ammonia cracking device, and achieve miniaturization, making it suitable for smaller scenarios such as vehicle-mounted.

[0035] 5. In view of the low exhaust temperature under low-temperature conditions of the engine, in order to prevent the misfire of the ammonia engine, quartz wire heating is adopted. It not only solves the problem of low ammonia cracking efficiency under low exhaust temperature conditions, but also quartz wire heating can achieve high-density uniform heating, which can improve the timeliness of the cracking device and the uniformity of cracking.

[0036] 6. The present invention provides a real-time, low-cost hydrogen production device for an ammonia-hydrogen engine / fuel cell. Through the online cracking hydrogen production device, the ammonia fuel as a raw material can be quickly produced into hydrogen fuel that is easy to react and burn online in real time, thereby significantly improving the reaction rate and system efficiency of the ammonia-hydrogen engine / fuel cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 This is a schematic diagram of the overall structure of the ammonia catalytic cracking hydrogen production device provided by the present invention;

[0038] Figure 2 for Figure 1 Schematic diagram of the structure of the hydrogen production system of catalytic cracking of ammonia;

[0039] Figure 3 for Figure 2 A schematic diagram of the partial structure of the ammonia catalytic cracking tube on the side;

[0040] Figure 4 for Figure 1 Schematic diagram of the structure of the nitrogen and hydrogen separation system;

[0041] Figure 5 for Figure 4 Schematic diagram of the structure of the spiral bending tube;

[0042] Figure 6 A schematic diagram of the control system principle of the ammonia catalytic cracking hydrogen production device provided by the present invention;

[0043] Figure 7 This is a schematic diagram of the coordination and process principle of the ammonia catalytic cracking hydrogen production device and control system.

[0044] Throughout the drawings, the same reference numerals are used to denote the same elements or structures, wherein:

[0045] 100-Ammonia catalytic cracking hydrogen production system; 200-Nitrogen-hydrogen separation system;

[0046] 101-exhaust pipe, 102-exhaust air inlet; 103-ammonia cracking tube; 104-ammonia air inlet, 105-cracking mixed gas outlet, 106-insulation tube, 107-electrode, 108-temperature sensor; 109-catalyst, 110-exhaust gas outlet; 111-first spiral bending tube; 112-metal plate, 113-fin, 114-heating plate;

[0047] 201-air guide pipe; 202-water bath chamber, 203-nitrogen outlet; 204-water pump, 205-circulating water pipe, 206-second spiral bending pipe, 207-ammonia water heating chamber; 208-ammonia outlet; 209-hydrogen outlet, 210-ammonia recovery outlet, 211-gas-water separator and dryer. DETAILED DESCRIPTION

[0048] In order to make the purpose, technical scheme and advantages of the present invention clearer, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0049] See also Figure 1-4The present invention provides an ammonia catalytic cracking hydrogen production device based on the utilization of engine exhaust waste heat, the purpose of which is to promote the hydrogen supply of the ammonia engine with efficient and reliable combustion, mainly including an ammonia catalytic cracking hydrogen production system and a nitrogen-hydrogen separation system. The ammonia catalytic cracking hydrogen production system includes an exhaust pipe 101 and an ammonia cracking tube 103 and an insulation tube 106 wrapped in the outer wall of the exhaust pipe 101 in sequence; the ammonia cracking tube 103 includes an ammonia inlet 104 and a cracked mixed gas outlet 105, which is used to introduce ammonia from the ammonia inlet 104 to the ammonia cracking tube 103, and the mixed gas is discharged from the cracked mixed gas outlet 105 after the cracking is completed. In order to increase the cracking rate of ammonia, the ammonia cracking tube is installed at the high temperature part of the exhaust pipe 101 as much as possible.

[0050] A gap is left between the inner wall of the ammonia cracking tube 103 and the outer wall of the exhaust pipe 101, and the gap is usually filled with a series of porous non-precious metals (iron, cobalt, and nickel) loaded on cerium-doped zirconium oxide semiconductor catalysts for cracking ammonia; the exhaust pipe 101 is connected to the engine cylinder to discharge the high-temperature exhaust gas generated in the engine cylinder, and at the same time, the ammonia in the ammonia cracking tube is cracked using the waste heat of the exhaust gas generated.

[0051] The nitrogen-hydrogen separation system includes a hydrogen separation unit, a nitrogen separation unit and an ammonia recovery unit; the cracked mixed gas outlet 105 of the ammonia cracking tube 103 is connected to the hydrogen separation unit; the ammonia recovery unit includes an ammonia water heating chamber 207, and the exhaust pipe 101 runs through the ammonia water heating chamber 207, thereby continuing to utilize the waste heat of the exhaust gas in the exhaust pipe 101 to promote the decomposition of ammonia water and the recovery of ammonia.

[0052] In particular, see Figure 2 The outer wall of the exhaust pipe 101 and the inner wall of the ammonia cracking tube 103 are both provided with fins 113 arranged at intervals to form a maze structure, which is used to expand the heat exchange area between the exhaust gas and the heating energy, thereby promoting sufficient heat exchange between ammonia and the exhaust gas, and can slow down the flow rate of the ammonia fuel, further promoting the cracking efficiency of ammonia.

[0053] In some embodiments, a metal plate 112 is installed close to the outer wall of the exhaust pipe 101, and then a fin 113 is installed on the metal plate 112. The fin 113 is a good thermal conductor, and preferably a thermal conductive adhesive is adhered between the metal plate 112 and the outer wall of the exhaust pipe 101 to improve the transfer effect of the exhaust heat flow. The structure of the fin 113 is preferably composed of a thermally conductive metal sheet and a thermally conductive column. The thermally conductive metal sheet can increase the heat transfer area, and the thermally conductive column can contact the inner wall of the ammonia cracking tube 103 to improve the uniformity of temperature distribution in the ammonia channel.

[0054] A heating plate 114 and an electrode 107 connected to the heating plate 114 are also provided between the ammonia cracking tube 103 and the insulation tube 106, which are used to generate heat to supplement heat for ammonia cracking when the exhaust waste heat is insufficient when the engine is started, so as to reach a suitable working temperature. The heating plate 114 is preferably a quartz wire heating plate, and the electrode 107 is preferably a high-voltage electrode. Uniform heating with high energy density can be achieved, and heating for catalytic cracking of ammonia can be performed under low working conditions or when the exhaust pipe temperature is insufficient at the time of startup to ensure the normal progress of the reaction. The high-voltage electrodes 107 arranged at both ends can also provide the catalyst with the current required for catalysis, and the high-voltage electrodes 107 are shared with the quartz wire to form an integrated heating catalytic device. The high-voltage electrode 107 is used to control the current passing through the catalyst. When ammonia enters the ammonia cracking tube 103 and the temperature sensor 108 detects different temperatures, the voltage will be adjusted to provide the current intensity with the highest catalytic efficiency at the current temperature.

[0055] The heat-insulating tube 106 is a tube made of high-temperature resistant heat-insulating material, which can reduce the heat loss of the catalytic process and improve the utilization rate of heat energy. The electrode 107 is usually arranged at the ammonia inlet 104, and the heating plate covers the outer wall of the ammonia cracking tube 103. The ammonia cracking tube 103 is preferably a metal material with good thermal conductivity. The temperature of the heating plate transfers heat to the internal gap through the fins 113 on the inner wall of the ammonia cracking tube 103.

[0056] See also Figure 3 The inner wall fins 113 are connected to the exhaust pipe 101 through the inner metal plate 112 and the thermal conductive adhesive, and are connected to the quartz wire heating plate 114 through the outer metal plate (i.e., the tube wall of the ammonia cracking tube 103). The fins are designed with thermal conductive columns connected to the inner and outer metal plates to improve the thermal conductivity.

[0057] With such an arrangement, the catalyst utilizes the waste heat of the exhaust pipe 101 and the heat transfer of the quartz wire to perform catalytic cracking of ammonia under different temperature conditions. For example, under normal engine operating conditions (the temperature in the pipe is about 400°C), ammonia can achieve a relatively high cracking efficiency (about 60%). Under lower power conditions, the ammonia cracking efficiency will be relatively reduced (about 50%).

[0058] A temperature sensor 108 is also provided in the ammonia cracking tube 103. The catalyst catalyzes the cracking of ammonia, and the temperature sensor 108 is used to monitor the temperature of the catalyst. The temperature sensor 108 is used to monitor the temperature in the ammonia cracking tube 103. When the temperature is detected to be lower than the set temperature, the quartz wire will be started to heat the catalyst. After the engine runs for a period of time, when it is detected that the temperature in the cracking tube reaches the set temperature, the quartz wire will be stopped.

[0059] See also Figure 4The hydrogen separation unit includes an air pipe 201 connected to the cracked mixed gas outlet 105, which is used to introduce the mixed gas of nitrogen, ammonia and hydrogen from the cracked mixed gas outlet 105. The air pipe 201 includes a hydrogen outlet 209 and a mixed gas outlet 210 (ammonia and ammonia); a hydrogen separation membrane (hydrogen molecular sieve membrane) is provided at the hydrogen outlet 209, which is used for the selective passage of hydrogen and is exported to the hydrogen storage tank. The air pipe 201 is perpendicular to the horizontal plane, and the hydrogen outlet 209 is preferably arranged in the middle of the air pipe 201, and the outlet direction is parallel to the horizontal plane (so that the air pipe 201 is a T-shaped structure). The middle end of the air pipe 201 is equipped with an anti-backflow device to prevent backflow caused by the pressure difference of the gas caused by gas dissolution. The volume at the hydrogen outlet is increased, which can reduce the flow rate of the cracked gas and improve the hydrogen leakage efficiency.

[0060] The nitrogen separation unit includes a water bath 202, which is filled with water (for dissolving ammonia to form ammonia water, which is separated from nitrogen), and does not fill the entire water bath 202, so as to leave space for guiding the nitrogen away; a mixed gas outlet 210 extends into the water of the water bath 202, and a nitrogen outlet 203 is provided at the top of the water bath 202, for introducing nitrogen into the tail pipe and discharging it; and an ammonia water outlet is provided at the bottom. The nitrogen outlet is preferably provided with a pressure cap to slow down the gas flow rate and further promote the permeation efficiency of hydrogen.

[0061] The ammonia recovery unit includes an ammonia heating chamber 207 connected to the ammonia outlet, and an ammonia outlet 208 is provided on the top of the ammonia heating chamber 207. The ammonia in the ammonia heating chamber 207 is decomposed under the residual heat of the tail gas in the exhaust pipe 101 to release ammonia, and the ammonia is discharged from the ammonia outlet 208. In particular, a gas-water separator and a dryer 211 are provided at the ammonia outlet 208 to separate the water discharged with the ammonia, and dry the ammonia, and then discharge it through the ammonia recovery outlet 210. The ammonia recovery outlet 210 can introduce the ammonia into the ammonia cracking tube 103 through the air guide pipe of the high-speed ammonia gas flow, and the ammonia overflowed by heating is recovered to the ammonia cracking tube 103 for reuse.

[0062] The water bath chamber 202 and the ammonia heating chamber 207 are connected by a circulating water pipe 205 and a second spiral bending pipe 206 (similar to Figure 5 The structure in the middle is placed horizontally to reduce the flow resistance caused by gravity) and the circulating water pipe 205 is connected with a water pump 204 to provide power for the water circulation. The water in the water bath 202 dissolves ammonia and flows into the ammonia heating chamber 207. After the ammonia escapes due to heat, it is completely separated from the water through the gas-water separator and the dryer 211, and is recycled and reused through the ammonia recovery outlet 210. The remaining water is then circulated into the water bath 202 through the second spiral bending pipe 206. The second spiral bending pipe 206 helps to dissipate the heat of the liquid flowing out of the ammonia heating chamber 207 and then circulates into the water bath 202.

[0063] In particular, see Figure 5 The portion of the exhaust pipe 101 passing through the ammonia heating chamber 207 is set as a first spiral bending pipe 111 to increase the heat exchange area. A temperature monitoring device is provided in the exhaust pipe 101, and an ammonia concentration monitoring device is provided in the ammonia cracking pipe 103. The ammonia concentration detection device is used to detect the ammonia concentration in the air guide pipe. When the ammonia concentration in the air guide pipe is greater than a certain value, the input rate of ammonia will be controlled to be reduced until the ammonia concentration reaches a suitable range.

[0064] Existing ammonia engines are unable to prepare high-purity hydrogen in real time, and there is also the problem of cracking failure under startup conditions and low-temperature exhaust conditions. The ammonia catalytic cracking hydrogen production device proposed in the present invention can realize real-time catalytic cracking of ammonia fuel to prepare high-purity hydrogen, and can achieve full operating condition adaptation, suitable for reliable and efficient ignition of ammonia engines under all operating conditions.

[0065] See also Figure 6 and 7 As shown, the present invention also provides an electronic control system for an ammonia catalytic cracking hydrogen production device, comprising a temperature monitoring unit, a temperature control unit, an ammonia concentration monitoring unit and an ammonia intake rate control unit; the temperature monitoring unit is used to monitor the catalytic cracking temperature in the ammonia cracking tube 103, and transmit the monitoring result to the temperature control unit, and the temperature control unit is used to control the temperature of the heating plate 114 to adapt to different exhaust conditions; the ammonia concentration monitoring unit is used to monitor the concentration of ammonia in the ammonia cracking tube 103, and transmit the monitoring result to the ammonia intake rate control unit, and the ammonia intake rate control unit is used to control the ammonia intake rate.

[0066] Specifically, an exhaust pipe temperature monitoring device is also installed in the exhaust pipe 101, and its electronic control system is connected to the central control system, which is used to convert the monitored temperature signal into an electrical signal and transmit it to the central control system. After collecting the electrical signal, the central control system sends an electrical signal to control the quartz wire to adjust the temperature. The exhaust pipe temperature monitoring device can monitor in advance whether the temperature of the exhaust pipe itself is sufficient to maintain catalytic cracking. If it is not enough, it can send an electrical signal in advance to control the heating of the quartz wire to prevent the initial temperature from being insufficient, resulting in low ammonia cracking efficiency.

[0067] This device is designed with energy-saving multi-gear working modes, which can change its own working mode according to the working conditions of the engine / fuel cell, and can adapt to different power requirements: when the ammonia catalytic cracking hydrogen production system is under low power conditions or when the engine is just started, the exhaust pipe temperature is insufficient. At this time, the quartz wire of the catalytic cracking device will provide heat to ensure the catalytic efficiency and ensure the sustainability of the vehicle. Under high power conditions, the exhaust waste heat is sufficient, and the catalytic device and the ammonia separation heating chamber will use the waste heat in the exhaust pipe to achieve waste heat utilization and achieve energy saving.

[0068] The catalyst temperature monitoring device is placed in the ammonia cracking tube 103, and its electronic control system is connected to the central control system, and is used to convert the monitored temperature signal into an electrical signal and transmit it to the central control system. After collecting the electrical signal, the central control system sends an electrical signal to control the high-voltage electrode to adjust the voltage and control the current to achieve the highest catalytic efficiency of the catalyst at this temperature.

[0069] The ammonia concentration monitoring device is placed in the ammonia cracking tube 103, and its electronic control system is connected to the central control system, which is used to convert the detected ammonia concentration signal into an electrical signal and transmit it to the central control system. After collecting the electrical signal, the central control system sends an electrical signal to control the ammonia intake device to adjust the ammonia intake rate.

[0070] The working principle of the ammonia catalytic cracking hydrogen production device based on the utilization of engine exhaust waste heat provided by the present invention is as follows: the engine exhaust gas is introduced into the exhaust inlet 102 of the exhaust pipe 101 in real time and discharged from the exhaust outlet 110. During this process, ammonia is introduced into the ammonia inlet 104 of the ammonia cracking tube 103 equipped with a catalyst, and the heat of the engine exhaust gas is used to promote the cracking of ammonia into nitrogen and hydrogen; when the heat is insufficient, the heating plate is powered on to supplement the heat; the mixed gas generated by the cracking includes nitrogen, hydrogen and incompletely cracked ammonia; the cracked mixed gas is introduced into the air guide pipe 201 through the cracking mixed gas outlet 105, and the hydrogen selectively passes through the hydrogen separation membrane of the hydrogen outlet 209 to achieve separation; the remaining nitrogen and ammonia are introduced into the water bath 202 from the bottom outlet of the air guide pipe 201, the ammonia is dissolved in the water to form ammonia water, and the nitrogen is discharged from the upper air part through the nitrogen outlet 203 for collection. Ammonia water flows into the ammonia water heating chamber 207 through the circulating water pipe 205, and is heated and decomposed under the residual heat of the engine exhaust gas flowing through the ammonia water heating chamber 207 to form ammonia gas, which escapes from the ammonia outlet 208. The remaining water is circulated into the water bath chamber 202 through the second spiral bending pipe 206 under the power of the water pump 204, so as to be reused. The second spiral bending pipe 206 can promote heat loss and prevent the temperature from being too high, which causes a large amount of ammonia gas to escape from the water bath chamber 202. The recovered ammonia gas can be circulated into the ammonia cracking pipe 103 for cracking.

[0071] It will be easily understood by those skilled in the art that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. An ammonia catalytic cracking hydrogen production device based on the utilization of engine exhaust waste heat, characterized in that: The invention comprises an ammonia catalytic cracking hydrogen production system and a nitrogen-hydrogen separation system. The ammonia catalytic cracking hydrogen production system comprises an exhaust pipe (101) and an ammonia cracking pipe (103) and a heat insulation pipe (106) which are sequentially wrapped around the outer wall of the exhaust pipe (101); the ammonia cracking pipe (103) comprises an ammonia inlet (104) and a cracked mixed gas outlet (105); a gap is left between the inner wall of the ammonia cracking pipe (103) and the outer wall of the exhaust pipe (101) for the circulation and cracking of ammonia; the exhaust pipe (101) is used to discharge engine exhaust gas; The nitrogen-hydrogen separation system comprises a hydrogen separation unit, a nitrogen separation unit and an ammonia recovery unit which are connected in sequence; the hydrogen separation unit is connected to the cracked mixed gas outlet (105); the ammonia recovery unit comprises an ammonia water heating chamber (207), and the exhaust pipe (101) passes through the inside of the ammonia water heating chamber (207).

2. The ammonia catalytic cracking hydrogen production device based on engine exhaust waste heat utilization according to claim 1 is characterized in that: The outer wall of the exhaust pipe (101) and the inner wall of the ammonia cracking pipe (103) are provided with fins arranged at intervals to increase the heat transfer area; A heating plate (114) and an electrode (107) connected to the heating plate (114) are also provided between the ammonia cracking tube (103) and the insulation tube (106) to supplement heat for cracking of the ammonia.

3. The ammonia catalytic cracking hydrogen production device based on engine exhaust waste heat utilization according to claim 1 is characterized in that: A catalyst and a temperature sensor (108) are also provided in the ammonia cracking tube (103). The catalyst is used to catalyze the cracking of the ammonia, and the temperature sensor (108) is used to monitor the temperature of the catalyst.

4. The ammonia catalytic cracking hydrogen production device based on engine exhaust waste heat utilization according to any one of claims 1 to 3, characterized in that: The hydrogen separation unit comprises an air guide pipe (201) connected to the cracked mixed gas outlet (105), and the air guide pipe (201) comprises a hydrogen outlet (209) and a mixed gas outlet (210); the hydrogen outlet (209) is provided with a hydrogen separation membrane for selective passage of hydrogen.

5. The ammonia catalytic cracking hydrogen production device based on engine exhaust waste heat utilization according to claim 4 is characterized in that: The nitrogen separation unit comprises a water bath chamber (202), wherein the water bath chamber (202) is filled with water but does not fill the entire water bath chamber (202); the mixed gas outlet (210) extends into the water of the water bath chamber (202); a nitrogen outlet (203) is provided at the top of the water bath chamber (202), and an ammonia outlet is provided at the bottom.

6. The ammonia catalytic cracking hydrogen production device based on engine exhaust waste heat utilization according to claim 5 is characterized in that: The ammonia recovery unit comprises an ammonia heating chamber (207) connected to the ammonia outlet, and an ammonia outlet (208) is provided on the top of the ammonia heating chamber (207). The ammonia in the ammonia heating chamber (207) is decomposed under the effect of the residual heat of the engine exhaust gas in the exhaust pipe (101) to release ammonia, which is then discharged from the ammonia outlet (208).

7. The ammonia catalytic cracking hydrogen production device based on engine exhaust waste heat utilization according to claim 6 is characterized in that: The water bath chamber (202) and the ammonia water heating chamber (207) are connected via a circulating water pipe (205) and a second spirally bent pipe (206), and a water pump (204) is provided on the circulating water pipe (205); the water in the water bath chamber (202) dissolves ammonia and flows into the ammonia water heating chamber (207); after the ammonia escapes due to heat, the remaining water is circulated through the second spirally bent pipe (206) and introduced into the water bath chamber (202).

8. The ammonia catalytic cracking hydrogen production device based on engine exhaust waste heat utilization according to claim 6 is characterized in that: The portion of the exhaust pipe (105) passing through the ammonia water heating chamber (207) is configured as a first spirally bent pipe (111) for increasing the heat exchange area; a temperature monitoring device is provided in the exhaust pipe (101), and an ammonia concentration monitoring device is provided in the ammonia cracking pipe (103).

9. A control system for an ammonia catalytic cracking hydrogen production device based on engine exhaust waste heat utilization according to any one of claims 1 to 8, characterized in that: The invention comprises a temperature monitoring unit, a temperature control unit, an ammonia concentration monitoring unit and an ammonia intake rate control unit; the temperature monitoring unit is used to monitor the catalytic cracking temperature in the ammonia cracking tube (103) and transmit the monitoring result to the temperature control unit, and the temperature control unit is used to control the temperature of the heating plate (114) to adapt to different exhaust conditions; the ammonia concentration monitoring unit is used to monitor the ammonia concentration in the ammonia cracking tube (103) and transmit the monitoring result to the ammonia intake rate control unit, and the ammonia intake rate control unit is used to control the ammonia intake rate.

10. A control method for an ammonia catalytic cracking hydrogen production device based on engine exhaust waste heat utilization according to any one of claims 1 to 8, characterized in that: The control system of claim 9 comprises: introducing the engine exhaust gas from the exhaust inlet (102) of the exhaust pipe (101) in real time and leading it out from the exhaust outlet (110), and introducing ammonia from the ammonia inlet (104) of the ammonia cracking tube (103) equipped with a catalyst; the mixed gas produced by cracking is successively separated and recovered from the hydrogen separation unit, the nitrogen separation unit and the ammonia recovery unit to complete the separation and recovery of hydrogen, nitrogen and ammonia; at the same time, the catalytic cracking temperature in the ammonia cracking tube (103) is monitored by the temperature monitoring unit, and the monitoring result is transmitted to the temperature control unit to control the temperature of the heating plate (114) to adapt to different exhaust conditions; the ammonia concentration monitoring unit monitors the concentration of ammonia in the ammonia cracking tube (103), and transmits the monitoring result to the ammonia intake rate control unit to control the intake rate of the ammonia.

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