Formic acid liquid phase / vapor phase cascade hydrogen production system powered by waste heat of power device

Abstract

The invention relates to the technical field of new energy hydrogen production, in particular to a formic acid liquid phase / vapor phase cascade hydrogen production system powered by waste heat of a power device. According to the system, waste heat generated in the operation process of power devices such as a hydrogen fuel cell engine can be fully utilized to heat formic acid hydrogen production reaction liquid, the temperature of the reaction liquid is increased, then the formic acid decomposition hydrogen production performance is enhanced, hydrogen produced by formic acid enters a hydrogen power device after being purified, and a hydrogen source is provided for the hydrogen power device.

Description

Technical Field

[0001] This invention relates to the field of new energy hydrogen production technology, specifically a formic acid liquid / vapor phase cascade hydrogen production system powered by waste heat from a power plant. Background Technology

[0002] Solid / liquid chemical materials (such as formic acid, methane, etc.) are considered to be promising hydrogen storage materials due to their safety and high hydrogen storage density, but their hydrogen release suffers from slow reaction kinetics.

[0003] Formic acid (HCOOH) is chemically stable, liquid at room temperature and pressure, and has a high hydrogen content (4.8 wt%). Formic acid can undergo dehydrogenation under catalysis at room temperature and pressure to release H2. The catalytic cracking of formic acid to produce hydrogen is significantly positively correlated with the reaction temperature; therefore, increasing the reaction temperature is crucial for improving the efficiency of formic acid cracking to produce hydrogen.

[0004] Hydrogen fuel cell engines generate a large amount of low-to-medium temperature (>90°C) heat during operation. This heat is often released as waste heat, resulting in significant energy waste. Scientifically utilizing the waste heat generated during the operation of the hydrogen fuel cell engine system to heat the formic acid hydrogen production reaction system can improve hydrogen production efficiency. Furthermore, formic acid cracking can provide a partial hydrogen source for the hydrogen fuel cell engine.

[0005] Therefore, coupling the waste heat resources of hydrogen fuel cell engines with formic acid cracking hydrogen production systems is the most promising technical approach to realize the utilization of waste heat from hydrogen fuel cell engines and improve the efficiency of formic acid cracking hydrogen production. Summary of the Invention

[0006] To address the technical challenges of utilizing waste heat resources from hydrogen fuel cell engines and improving the performance of formic acid in hydrogen production, this invention aims to provide a formic acid liquid / vapor phase cascade hydrogen production system powered by waste heat from power devices. This system can fully utilize the waste heat generated during the operation of power devices such as hydrogen fuel cell engines to heat the formic acid hydrogen production reaction liquid, thereby increasing the temperature of the reaction liquid and enhancing the performance of formic acid decomposition for hydrogen production.

[0007] A formic acid liquid / vapor staged hydrogen production system powered by waste heat from a power unit includes a circulating water peristaltic pump, a waste heat recovery tank, a formic acid reactor, a mixed gas cooler, and a hydrogen purification chamber. The formic acid reactor includes a formic acid liquid phase reactor and a formic acid vapor phase reactor, which are connected in series from bottom to top. Both the liquid and vapor phase reactors are located inside the waste heat recovery tank and have gaps between them and the inner wall of the tank to allow for circulating water flow. The inlet of the circulating water peristaltic pump is connected to the cooling water outlet of the hydrogen power system, the outlet of the circulating water peristaltic pump is connected to the circulating water inlet of the waste heat recovery tank, and the circulating water outlet of the waste heat recovery tank is connected to the cooling water inlet of the hydrogen power system. The gas outlet of the formic acid vapor phase reactor is connected to the gas inlet of the mixed gas cooler, the condensate outlet of the mixed gas cooler is connected to the condensate inlet of the formic acid liquid phase reactor, the gas outlet of the mixed gas cooler is connected to the inlet of the hydrogen purification chamber, and the outlet of the hydrogen purification chamber is connected to the hydrogen power system.

[0008] Furthermore, the circulating water inlet is located at the lower part of one side of the waste heat recovery tank, and the circulating water outlet is located at the upper part of one side of the waste heat recovery tank.

[0009] Furthermore, a circulating water regulating valve is installed between the circulating water outlet and the cooling water inlet of the hydrogen power unit.

[0010] Furthermore, the outlet of the formic acid liquid phase reactor at the top is connected to the inlet of the formic acid vapor phase reactor at the bottom via a first riser pipe.

[0011] Furthermore, the gas outlet of the formic acid vapor phase reactor at the top is connected to the gas inlet of the mixed gas cooler via a second riser pipe; the mixed gas cooler is located above the formic acid vapor phase reactor.

[0012] Furthermore, the condensate outlet at the lower end of the mixed gas cooler is connected to the condensate inlet at the top of the formic acid liquid phase reactor via a liquid downcomer; the gas outlet port is located on one side of the mixed gas cooler.

[0013] Furthermore, a gas shut-off valve is provided between the gas outlet port and the inlet of the hydrogen purification chamber; a hydrogen pressurization pump is also provided between the outlet of the hydrogen purification chamber and the hydrogen power system.

[0014] Furthermore, the formic acid liquid phase reactor is also equipped with a controllable electromagnetic stirrer.

[0015] Furthermore, a feed pipe is connected to one side of the formic acid liquid phase reactor, and the end of the feed pipe with the feed port passes through the tank body of the waste heat recovery tank and is located outside the tank body.

[0016] Furthermore, the hydrogen purification chamber is equipped with a formic acid vapor / CO2 gas combined removal zone and a gas dehumidification zone arranged sequentially along the gas flow direction.

[0017] Furthermore, the formic acid vapor / CO2 gas combined removal zone is equipped with an absorbent for absorbing formic acid vapor and CO2. The absorbent for absorbing formic acid vapor or CO2 includes one or more alkaline solutions. The gas dehumidification zone is equipped with a desiccant, which includes one or more of calcium chloride (CaCl2) or SiO2.

[0018] Furthermore, the formic acid liquid-phase / vapor-phase stepped hydrogen production system also includes a thermocouple temperature sensor. The thermocouple temperature sensor includes a temperature measurement module and a temperature control module. The temperature measurement module includes a thermocouple, which is inserted into the liquid in the formic acid liquid-phase reactor to monitor the temperature of the formic acid liquid in real time. The temperature signal from the thermocouple is transmitted to the temperature control module in real time. The temperature control module outputs a control signal to regulate the circulating water volume of the circulating water peristaltic pump, thereby controlling the temperature of the formic acid liquid and the evaporation rate of formic acid. That is, the temperature control module and the circulating water peristaltic pump are interlocked for control.

[0019] Furthermore, the circulating water outlet is located at the top of the formic acid vapor phase reactor.

[0020] Furthermore, a catalyst is added to the formic acid liquid in the formic acid liquid phase reactor.

[0021] Furthermore, the formic acid vapor phase reactor is horizontally equipped with multiple layers of nickel foam mesh, which are uniformly coated with a catalyst for the production of hydrogen from formic acid vapor.

[0022] Furthermore, both the catalyst added to the formic acid liquid and the catalyst coated with nickel foam mesh are trimetallic catalysts PdCuCo / CeO2, wherein the active metal is PdCuCo and the support is CeO2, ensuring uniform loading of the active metal components and preventing the formation of clusters of the active metal. CeO2 also exhibits good resistance to formic acid corrosion. The total active metal loading of the catalyst in this invention is 5%-15% (mass fraction), with the mass ratio of the trimetallic Pd, Cu, and Co loading being 6:2:2. The method for loading the active metal alloy nanoclusters onto the CeO2 support is a liquid-phase reduction method.

[0023] Furthermore, the trimetallic catalyst PdCuCo / CeO2 is prepared by the following method: Palladium chloride (PdCl2), copper nitrate (Cu(NO3)2), and cobalt nitrate (Co(NO3)2) are mixed evenly and dissolved in anhydrous ethanol to form a mixed salt solution. Then CeO2 is added and mixed evenly to obtain mixed solution A. Mixed solution A is then cooled to 0°C. Freshly prepared 0.5 mol / L sodium borohydride solution is added dropwise to the above mixed solution A at 0°C until the amount of sodium borohydride reducing agent added is in excess relative to the metal salts to be reduced (i.e., palladium chloride, copper nitrate, and cobalt nitrate). During this process, the mixture is stirred continuously. After the addition is completed, the mixture is reacted for 2 hours under stirring. The resulting solution is centrifuged, and the precipitate obtained by centrifugation is dried and calcined at 600°C for 8 hours under an argon atmosphere. The resulting solid is the catalyst PdCuCo / CeO2.

[0024] Furthermore, in the above preparation method of PdCuCo / CeO2, after adding CeO2, it is ultrasonically dispersed for 30 minutes and magnetically stirred with an electromagnetic stirrer for 50 minutes to make it uniformly mixed, thus obtaining mixed solution A.

[0025] Compared with the prior art, the present invention has the following beneficial effects: This invention's reactor is configured with both liquid-phase and vapor-phase reaction modes, achieving a stepped hydrogen production process from formic acid via liquid-phase and vapor-phase reactions. This further improves energy utilization efficiency and enhances the hydrogen production performance of formic acid decomposition. The produced hydrogen does not contain impurities such as CO, which are toxic to hydrogen fuel cells, and can supply hydrogen to hydrogen-powered devices such as hydrogen fuel cell engines. This hydrogen production system can couple waste heat utilization from power plant operation with efficient hydrogen production. The system is simple and easy to automate. It is suitable for use with mobile hydrogen-powered devices (such as hydrogen fuel cell engines and hydrogen internal combustion engines). Attached Figure Description

[0026] Figure 1 This is a schematic diagram illustrating the working principle of the formic acid liquid / vapor phase cascade hydrogen production system powered by waste heat from the power unit of the present invention. Figure 2 This is a schematic diagram of the nickel foam mesh used to spray the catalyst in the formic acid vapor phase reactor of the present invention; Figure 3 The graph shows the rate of gas production from the catalytic decomposition of formic acid at different temperatures. The horizontal axis represents the reaction time in seconds, and the vertical axis represents the volume of gas produced in milliliters.

[0027] Figure 4 A gas chromatographic analysis of the mixed gas produced by the decomposition of formic acid without gas purification. Figure 5 This is a gas chromatographic graph showing the mixed gas produced by the decomposition of formic acid after gas purification.

[0028] Figure Labels 101-Formic acid reactor, 1011-Formic acid liquid phase reactor, 1012-Formic acid vapor phase reactor, 102-Mixed gas cooler, 103-Thermocouple temperature sensor, 104-Gas shut-off valve, 105-Hydrogen purification chamber, 106-Hydrogen pressurization pump, 107-Circulating water regulating valve, 108-Circulating water peristaltic pump, 109-Hydrogen power system. Detailed Implementation

[0029] To better understand the content of this invention, it will be further described below with reference to specific embodiments and accompanying drawings. The following embodiments are based on the technology of this invention and provide detailed implementation methods and operating steps, but the scope of protection of this invention is not limited to the following embodiments.

[0030] In the prior art, a hydrogen power system includes a hydrogen power unit and an operating waste heat management subsystem. The hydrogen power unit is equipped with a hydrogen inlet, and the operating waste heat management subsystem is equipped with a cooling water inlet and a cooling water outlet.

[0031] Please combine Figure 1-2 A formic acid liquid / vapor phase cascade hydrogen production system powered by waste heat from a power unit includes a circulating water peristaltic pump 108. The inlet of the circulating water peristaltic pump 108 is connected to the cooling water outlet of the waste heat management subsystem operating in the hydrogen power system 109. The outlet of the circulating water peristaltic pump 108 is connected to the circulating water inlet of the waste heat recovery tank. The circulating water inlet is located on the lower side of the tank body of the waste heat recovery tank. The circulating water outlet of the waste heat recovery tank is connected to the cooling water inlet of the waste heat management subsystem operating in the hydrogen power system 109. The circulating water outlet is located on the upper side of the tank body of the waste heat recovery tank. A circulating water regulating valve 107 is provided between the circulating water outlet and the cooling water inlet of the waste heat management subsystem operating in the hydrogen power system 109.

[0032] The waste heat recovery tank is equipped with a formic acid reactor 101. The formic acid reactor 101 includes a formic acid liquid phase reactor 1011 and a formic acid vapor phase reactor 1012. Both the formic acid liquid phase reactor and the formic acid vapor phase reactor are located inside the waste heat recovery tank and have gaps between them and the inner wall of the tank to allow for the flow of circulating water. The outlet at the top of the formic acid liquid phase reactor 1011 is connected to the inlet at the bottom of the formic acid vapor phase reactor 1012 via a first riser pipe. The gas outlet at the top of the formic acid vapor phase reactor 1012 is connected to the gas inlet of the mixed gas cooler 102 via a second riser pipe. The mixed gas cooler 102 is located above the formic acid vapor phase reactor 1012. The condensate outlet at the bottom of the mixed gas cooler 102 is connected to the condensate inlet at the top of the formic acid liquid phase reactor 1011 via a liquid downcomer pipe. A gas outlet port is provided on one side of the mixed gas cooler 102, which is connected to the inlet of the hydrogen purification chamber 105. A gas shut-off valve 104 is also provided between the gas outlet port and the inlet of the hydrogen purification chamber 105. The outlet of the hydrogen purification chamber 105 is connected to the hydrogen inlet of the hydrogen power unit in the hydrogen power system. A hydrogen pressurization pump 106 is also provided between the outlet of the hydrogen purification chamber 105 and the hydrogen inlet of the hydrogen power unit in the hydrogen power system.

[0033] The circulating water regulating valve 107 regulates the circulating water flow rate, thereby controlling the temperature of the formic acid liquid-phase reactor 1011 and the formic acid vapor-phase reactor 1012. Furthermore, the circulating water regulating valve 107 can isolate the formic acid hydrogen production system from the hydrogen power system in case of a malfunction. The gas shut-off valve 104 is a normally open valve, closing only during shutdown and emergency conditions, serving an isolation function.

[0034] The formic acid liquid phase reactor 1011 is also equipped with a controllable electromagnetic stirrer. A feed pipe is connected to one side of the formic acid liquid phase reactor 1011. The end of the feed pipe with the feed port passes through the tank body of the waste heat recovery tank and is located outside the tank body. Formic acid and catalyst enter the formic acid liquid phase reactor 1011 through the feed port.

[0035] The hydrogen purification chamber 105 is equipped with a formic acid vapor / CO2 gas combined removal zone and a gas dehumidification zone arranged sequentially along the gas flow direction.

[0036] The formic acid vapor / CO2 gas combined removal zone is equipped with absorbents for absorbing formic acid vapor and CO2. The absorbents for absorbing formic acid vapor or CO2 include one or more alkaline solutions. The desiccant packed in the gas dehumidification zone includes one or more of calcium chloride (CaCl2) or SiO2.

[0037] The formic acid liquid / vapor phase cascade hydrogen production system powered by waste heat from the power unit also includes a thermocouple temperature sensor 103. The thermocouple temperature sensor 103 includes a temperature measurement module and a temperature control module. In this embodiment, the temperature measurement module includes a thermocouple, which is inserted into the liquid in the formic acid liquid reactor 1011 to monitor the temperature of the formic acid liquid in real time. The temperature signal from the thermocouple is transmitted to the temperature control module in real time. The temperature control module outputs a control signal to regulate the circulation water volume of the circulating water peristaltic pump 108, thereby controlling the temperature of the formic acid liquid and the evaporation rate of formic acid.

[0038] In this embodiment, the circulating water outlet is located at the top of the formic acid vapor phase reactor 1012, so that both the formic acid liquid phase reactor 1011 and the formic acid vapor phase reactor 1012 can be heated by the high-temperature circulating water from the hydrogen power unit. In addition, a catalyst is added to the formic acid liquid in the formic acid liquid phase reactor 1011. The formic acid and the catalyst are mixed evenly by stirring with a controllable electromagnetic stirrer, and the reaction rate can be controlled by the rotation speed of the controllable electromagnetic stirrer.

[0039] The formic acid vapor phase reactor 1012 is horizontally equipped with multiple layers of nickel foam mesh, which are uniformly coated with a catalyst for the production of hydrogen from formic acid vapor.

[0040] The catalyst added to the formic acid liquid and the catalyst coated with nickel foam mesh are both trimetallic catalysts PdCuCo / CeO2, wherein the active metal component is PdCuCo and the support is CeO2, ensuring uniform loading of the active metal components. CeO2 has good resistance to formic acid corrosion. The total loading of active metals in the catalyst of this invention is 5%-15% (mass fraction), wherein the mass ratio of the trimetallic Pd, Cu, and Co loading is 6:2:2. The method for loading active metal alloy nanoclusters onto the CeO2 support is a liquid-phase reduction method. The specific preparation process is as follows: weigh a certain amount of palladium chloride (PdCl2), copper nitrate (Cu(NO3)2), and cobalt nitrate (Co(NO3)2), mix the above metal salts evenly, dissolve them in an appropriate amount of anhydrous ethanol to form a mixed salt solution, then add the CeO2 sample to the above mixed salt solution, disperse by ultrasonication for 30 min, and stir magnetically with an electromagnetic stirrer for 50 min to mix evenly, to obtain mixed solution A. Then, place mixed solution A in an ice-water mixture at 0℃. The solution was cooled to 0°C. Fresh 0.5 mol / L sodium borohydride solution was added dropwise to the above mixed solution A at 0°C until the amount of sodium borohydride reducing agent added was in excess relative to the metal salt to be reduced (i.e., palladium chloride, copper nitrate, cobalt nitrate). During this process, the solution was stirred continuously with a stirrer. After the addition was completed, the reaction was carried out for 2 hours under stirring. The resulting solution was centrifuged. The precipitate obtained after centrifugation was placed in a vacuum drying oven for drying. The resulting solid powder was then calcined at 600°C for 8 hours under an argon atmosphere. The resulting solid was the catalyst PdCuCo / CeO2.

[0041] The following are examples of preparing the trimetallic catalyst PdCuCo / CeO2: Example 1: Weigh out 0.50g palladium chloride (PdCl2), 0.29g copper nitrate (Cu(NO3)2), and 0.31g cobalt nitrate (Co(NO3)2). Mix the above metal salts thoroughly and dissolve them in 20mL of anhydrous ethanol to form a mixed salt solution. Then, take 9.5g... The CeO2 sample was added to the above mixed salt solution and dispersed by ultrasonication for 30 min, followed by magnetic stirring with an electromagnetic stirrer for 50 min to ensure uniform mixing, resulting in mixed solution A. Mixed solution A was then cooled to 0°C in an ice-water mixture. 8 mL of fresh 0.5 mol / L sodium borohydride solution was added dropwise to the 0°C mixed solution A while continuously stirring. After the addition was complete, the mixture was reacted for 2 h under stirring. The resulting solution was centrifuged, and the precipitate was dried in a vacuum drying oven. The resulting solid powder was then calcined at 600°C for 8 h under an argon atmosphere. The resulting solid was the catalyst PdCuCo / CeO2, with a total loading of 5% of the active metals (Pd, Cu, and Co).

[0042] Example 2: Weigh out 0.99g palladium chloride (PdCl2), 0.59g copper nitrate (Cu(NO3)2), and 0.62g cobalt nitrate (Co(NO3)2). Mix the above metal salts thoroughly and dissolve them in 20mL of anhydrous ethanol to form a mixed salt solution. Then, add 9.0g... The CeO2 sample was added to the above mixed salt solution and dispersed by ultrasonication for 30 min, followed by magnetic stirring with an electromagnetic stirrer for 50 min to ensure uniform mixing, resulting in mixed solution A. Mixed solution A was then cooled to 0°C in an ice-water mixture. 8 mL of fresh 0.5 mol / L sodium borohydride solution was added dropwise to the 0°C mixed solution A while continuously stirring. After the addition was complete, the mixture was reacted for 2 h under stirring. The resulting solution was centrifuged, and the precipitate was dried in a vacuum drying oven. The resulting solid powder was then calcined at 600°C for 8 h under an argon atmosphere. The resulting solid was the catalyst PdCuCo / CeO2, in which the total loading of active metals (Pd, Cu, and Co) was 10%.

[0043] Example 3: Weigh out 1.49g palladium chloride (PdCl2), 0.88g copper nitrate (Cu(NO3)2), and 0.93g cobalt nitrate (Co(NO3)2). Mix the above metal salts thoroughly and dissolve them in 20mL of anhydrous ethanol to form a mixed salt solution. Then, add 8.5g... The CeO2 sample was added to the above mixed salt solution and dispersed by ultrasonication for 30 min, followed by magnetic stirring with an electromagnetic stirrer for 50 min to ensure uniform mixing, resulting in mixed solution A. Mixed solution A was then cooled to 0°C in an ice-water mixture. 10 mL of fresh 0.5 mol / L sodium borohydride solution was added dropwise to the 0°C mixed solution A while continuously stirring. After the addition was complete, the mixture was reacted for 2 h under stirring. The resulting solution was centrifuged, and the precipitate was dried in a vacuum drying oven. The resulting solid powder was then calcined at 600°C for 8 h under an argon atmosphere. The resulting solid was the catalyst PdCuCo / CeO2, in which the total loading of active metals (Pd, Cu, and Co) was 15%.

[0044] During operation, high-temperature circulating water flowing from the cooling water outlet of the waste heat management subsystem of the hydrogen power system 109 is sent to the circulating water inlet of the waste heat recovery tank by the circulating water peristaltic pump 108 and enters the tank. This high-temperature circulating water fills the gaps between the outer walls of the formic acid liquid phase reactor 1011 and the formic acid vapor phase reactor 1012, and the inner wall of the waste heat recovery tank. The high-temperature circulating water exchanges heat with the media inside the reactors through the walls of the formic acid liquid phase reactor 1011 and the formic acid vapor phase reactor 1012, respectively. After heat exchange, the lower-temperature circulating water enters the cooling water inlet of the waste heat management subsystem of the hydrogen power system through the circulating water regulating valve 107. Simultaneously, some formic acid liquid undergoes catalytic decomposition in the formic acid liquid phase reactor to produce H2 and CO2. After heat exchange, the formic acid liquid in the formic acid liquid phase reactor 1011 heats up and produces formic acid vapor. Formic acid vapor and H2... A mixture of H2 and CO2 enters the formic acid vapor phase reactor 1012 through the first riser pipe. The formic acid vapor passes through the holes of the nickel foam mesh and is catalytically decomposed by the catalyst coated on the surface of the nickel foam mesh to produce H2 and CO2. The mixture of the generated H2 and CO2 and the unreacted formic acid vapor is discharged from the gas outlet of the formic acid vapor phase reactor 1012 and then enters the mixed gas cooler. The formic acid vapor is cooled and condensed into liquid formic acid and re-enters the liquid formic acid reactor 1011 through the liquid downcomer. The non-condensable H2, CO2 and a small amount of formic acid vapor enter the hydrogen purification chamber 105 through the gas outlet port of the mixed gas cooler 102 and the gas shut-off valve 104. CO2 and formic acid vapor are removed in the hydrogen purification chamber 105. After leaving the hydrogen purification chamber, the pure hydrogen is pressurized by the hydrogen pressurization pump 106 and enters the hydrogen inlet of the hydrogen power unit to provide pure hydrogen for the hydrogen power unit.

[0045] Hot water from the waste heat management subsystem in the hydrogen power system is fed into the formic acid hydrogen production reactor to heat the formic acid. After the heat is released, it is returned to the hydrogen power system. The hydrogen produced from the formic acid is purified and then enters the hydrogen power unit. The water circulation power is provided by the circulating water peristaltic pump.

[0046] Figure 3 The graphs show the hydrogen production rates of formic acid catalyzed by the prepared catalyst under different temperature conditions, where the total metal loading is 8%. The catalyst Pd was synthesized utilizing the synergistic effect of heterometallic alloys. 0.6 Cu 0.2 Co 0.2 / CeO2 achieved catalytic activity comparable to that of pure noble metal Pd / CeO2 catalysts for formic acid decomposition, while ensuring the decomposition and hydrogen production rate and reducing the cost of catalyst use.

[0047] The gas exiting the formic acid reactor (specifically, from the gas outlet port of the formic acid vapor phase reactor 1012), after analysis by gas chromatography, is a mixture of hydrogen and carbon dioxide, free of impurities such as carbon monoxide. The gas chromatogram is shown below. Figure 4 As shown. The gas purified in the hydrogen purification chamber completely removes carbon dioxide from the mixed gas, outputting pure hydrogen. After analysis by a gas chromatograph, the purified gas shows no carbon dioxide. Figure 5 As shown.

[0048] The above description is merely an embodiment of the present invention and is not intended to limit the present invention in any way. The present invention can also have other embodiments based on the above structure and function, which will not be listed hereafter. Therefore, any simple modifications, equivalent changes, and alterations made by those skilled in the art to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A formic acid liquid-phase / vapor-phase cascade hydrogen production system powered by waste heat from a power plant, characterized in that, The system includes a circulating water peristaltic pump, a waste heat recovery tank, a formic acid reactor, a mixed gas cooler, and a hydrogen purification chamber. The formic acid reactor comprises a liquid-phase formic acid reactor and a vapor-phase formic acid reactor, which are connected in series from bottom to top. Both the liquid-phase and vapor-phase formic acid reactors are housed within the waste heat recovery tank, with gaps between them and the tank's inner wall. The inlet of the circulating water peristaltic pump is connected to the cooling water outlet of the hydrogen power system, and the outlet of the circulating water peristaltic pump is connected to the circulating water inlet of the waste heat recovery tank. The circulating water outlet of the waste heat recovery tank is connected to the cooling water inlet of the hydrogen power system. The gas outlet of the formic acid vapor-phase reactor is connected to the gas inlet of the mixed gas cooler, the condensate outlet of the mixed gas cooler is connected to the condensate inlet of the liquid-phase formic acid reactor, the gas outlet of the mixed gas cooler is connected to the inlet of the hydrogen purification chamber, and the outlet of the hydrogen purification chamber is connected to the hydrogen power system.

2. The formic acid liquid / vapor phase cascade hydrogen production system powered by waste heat from a power unit as described in claim 1, characterized in that, The circulating water inlet is located on the lower side of one side of the waste heat recovery tank, and the circulating water outlet is located on the upper side of one side of the waste heat recovery tank; a circulating water regulating valve is provided between the circulating water outlet and the cooling water inlet of the hydrogen power unit.

3. The formic acid liquid / vapor phase cascade hydrogen production system powered by waste heat from a power unit as described in claim 1, characterized in that, The outlet of the formic acid liquid phase reactor at the top is connected to the inlet of the formic acid vapor phase reactor at the bottom via a first riser pipe; the gas outlet of the formic acid vapor phase reactor at the top is connected to the gas inlet of the mixed gas cooler via a second riser pipe; the mixed gas cooler is located above the formic acid vapor phase reactor.

4. The formic acid liquid / vapor phase cascade hydrogen production system powered by waste heat from a power unit as described in claim 1, characterized in that, The condensate outlet at the lower end of the mixed gas cooler is connected to the condensate inlet at the top of the formic acid liquid phase reactor via a liquid downcomer; the gas outlet is located on one side of the mixed gas cooler; and the circulating water outlet is located at the top of the formic acid vapor phase reactor.

5. The formic acid liquid / vapor phase cascade hydrogen production system powered by waste heat from a power unit as described in claim 1, characterized in that, The hydrogen purification chamber is equipped with a formic acid vapor / CO2 gas combined removal zone and a gas dehumidification zone arranged sequentially along the gas flow direction; the formic acid liquid phase / vapor phase stepped hydrogen production system also includes a thermocouple temperature sensor, which includes a temperature measurement module and a temperature control module.

6. The formic acid liquid / vapor phase cascade hydrogen production system powered by waste heat from a power unit as described in claim 5, characterized in that, The formic acid vapor / CO2 gas combined removal zone is equipped with an absorbent to absorb formic acid vapor and CO2, and the gas dehumidification zone is equipped with a desiccant; the temperature measuring module includes a thermocouple, which is inserted into the liquid in the formic acid liquid phase reactor, and the temperature signal of the thermocouple is transmitted to the temperature control module in real time, and the temperature control module is interlocked with the circulating water peristaltic pump.

7. The formic acid liquid / vapor phase cascade hydrogen production system powered by waste heat from a power unit as described in claim 1, characterized in that, A feed pipe is connected to one side of the formic acid liquid phase reactor. The end of the feed pipe with the feed port passes through the tank body of the waste heat recovery tank and is located outside the tank body. A controllable electromagnetic stirrer is also provided inside the formic acid liquid phase reactor. A gas shut-off valve is also provided between the gas outlet port and the inlet of the hydrogen purification chamber. A hydrogen pressurization pump is also provided between the outlet of the hydrogen purification chamber and the hydrogen power system.

8. The formic acid liquid / vapor phase cascade hydrogen production system powered by waste heat from a power unit as described in claim 1, characterized in that, The liquid formic acid reactor also contains a catalyst; the vapor formic acid reactor is horizontally equipped with multiple layers of nickel foam mesh, which are uniformly coated with a catalyst for the production of hydrogen from formic acid vapor.

9. The formic acid liquid / vapor phase cascade hydrogen production system powered by waste heat from a power unit as described in claim 8, characterized in that, The catalyst added to the formic acid liquid and the catalyst coated with nickel foam mesh are both trimetallic catalysts PdCuCo / CeO2, wherein the active metal is PdCuCo and the support is CeO2, wherein the total loading of the active metal is 5%-15%, and the mass ratio of the three metals Pd, Cu, and Co is 6:2:2; the catalyst PdCuCo / CeO2 is prepared by liquid-phase reduction method.

10. The formic acid liquid / vapor phase cascade hydrogen production system powered by waste heat from a power unit as described in claim 9, characterized in that, The trimetallic catalyst PdCuCo / CeO2 was prepared by the following method: Palladium chloride, copper nitrate, and cobalt nitrate were mixed evenly and dissolved in anhydrous ethanol to form a mixed salt solution. CeO2 was then added and mixed evenly to obtain mixed solution A. Mixed solution A was then cooled to 0°C. Freshly prepared 0.5 mol / L sodium borohydride solution was added dropwise to the 0°C mixed solution A until the amount of sodium borohydride added as a reducing agent was in excess relative to the metal salt to be reduced. During this process, the mixture was stirred continuously. After the addition was completed, the mixture was reacted for 2 hours under stirring. The resulting solution was centrifuged, and the precipitate obtained by centrifugation was dried and calcined at 600°C for 8 hours under an argon atmosphere. The resulting solid was PdCuCo / CeO2.

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