Hydrogen production system and method by catalytic decomposition of steam assisted by geothermal energy

Abstract

The application discloses a geothermal-assisted catalytic water vapor decomposition hydrogen production system and method, which comprises a geothermal evaporation module, a catalytic reactor, a mixed condenser, a water supplement unit, a gas-liquid separation unit and a reflux pipeline; the geothermal evaporation module is used for extracting geothermal energy without pump, and water is evaporated by geothermal energy, so that a stable, continuous and low-cost water vapor source is provided for a gas-solid decoupling catalytic reaction, and the problems of high energy consumption of traditional electric heating and great influence of solar evaporation on weather are overcome. The system realizes integrated closed-loop operation of geothermal heat extraction-water vapor production-catalytic hydrogen production-product separation-self-water supplement, and especially solves the problems of unstable water vapor source of gas-solid decoupling, lack of efficient coupling between geothermal energy and solar energy and lack of active water supplement and water balance maintenance mechanism in long-term operation of the system in the prior art.

Description

Technical Field

[0001] This invention belongs to the field of hydrogen energy production technology, specifically relating to a geothermal-assisted catalytic decomposition of water vapor to produce hydrogen system and method, and more particularly to a system and method that uses geothermal evaporation modules (such as ultra-long gravity heat pipes) to extract geothermal energy to generate water vapor and then performs catalytic decomposition to produce hydrogen on the ground. Background Technology

[0002] Hydrogen energy, as a clean and efficient secondary energy source, is a key driver for the green transformation of the energy structure. Photocatalytic water splitting for hydrogen production is considered an ideal green hydrogen production route due to its advantages such as direct utilization of solar energy and mild reaction conditions. However, traditional liquid photocatalytic systems have long faced two major bottlenecks: first, the rapid recombination of photogenerated carriers leads to low quantum efficiency; second, the mass transfer resistance between dissolved oxygen and product bubbles severely restricts the reaction rate. To address these issues, a gas-solid decoupling strategy has emerged—by pre-converting liquid water into water vapor and then reacting it with a solid photocatalyst in a gas-solid phase photocatalytic reaction, the aforementioned problems can be effectively avoided.

[0003] In the area of ​​geothermal energy utilization, existing patents disclose devices for producing hydrogen from water through metal pyrolysis. This involves exchanging heat between the geothermal energy in the production well and the makeup water components before the water enters the metal pyrolysis reactor, saving the electricity consumed in heating water from ambient temperature. Furthermore, ultra-long gravity heat pipe technology has attracted attention due to its ability to efficiently extract medium-deep geothermal energy under pump-free conditions.

[0004] However, existing technologies still have the following shortcomings:

[0005] (1) The gas-solid decoupled photocatalytic reaction lacks a stable, efficient and low-cost source of water vapor.

[0006] (2) Geothermal energy and solar energy lack efficient coupling and utilization modes, and fail to achieve energy cascade complementarity and system integration.

[0007] (3) The existing system lacks an active water replenishment and water balance maintenance mechanism, making it difficult to achieve long-term continuous and stable operation.

[0008] Furthermore, existing technologies mostly employ a constant water replenishment strategy, failing to consider the drastic changes in hydrogen production rate caused by fluctuations in light and heat. In geothermal-driven systems with high inertia, such delayed water replenishment control can easily lead to the geothermal well working fluid 'evaporating dry' or condensation overload, severely affecting the long-term stability of the system. Summary of the Invention

[0009] The purpose of this invention is to overcome the shortcomings of the prior art and provide a geothermal-assisted catalytic decomposition of water vapor to produce hydrogen system and method, realizing the integrated closed-loop operation of geothermal heat extraction, water vapor production, catalytic hydrogen production, product separation and self-water replenishment, especially solving the problems of unstable water vapor source and lack of efficient coupling between geothermal and solar energy in the prior art.

[0010] To achieve the above objectives, the technical solution of the present invention is as follows:

[0011] A geothermal-assisted catalytic water vapor splitting hydrogen production system includes:

[0012] Geothermal evaporation module is used to absorb geothermal energy and convert liquid water into water vapor;

[0013] A catalytic reactor, whose inlet is connected to the outlet of the geothermal evaporation module, is used to receive the water vapor and decompose the water vapor into a mixed gas containing hydrogen and oxygen.

[0014] A mixing condenser, the inlet of which is connected to the outlet of the catalytic reactor, is used to receive the mixed gas;

[0015] A water replenishment unit is connected to the mixing condenser via a pipeline with a control valve to spray replenishment water into the mixing condenser to cool and partially condense the water vapor in the mixed gas.

[0016] A gas-liquid separation unit, the inlet of which is connected to the outlet of the mixing condenser, is used to separate condensate from uncondensed hydrogen.

[0017] A return pipeline connects the aqueous phase outlet of the gas-liquid separation unit to the inlet of the geothermal evaporation module, and is used to return the condensate and makeup water to the geothermal evaporation module.

[0018] A gas collection unit, connected to the gas phase outlet of the gas-liquid separation unit, is used to collect hydrogen gas.

[0019] Optionally, the geothermal-assisted catalytic water vapor splitting hydrogen production system further includes:

[0020] A flow sensor is used to measure the flow rate of the gaseous products in the catalytic reactor.

[0021] A control unit, connected to the control valve and flow sensor, adjusts the opening of the control valve according to the gas product flow rate of the catalytic reactor to control the flow rate of makeup water injected into the mixing condenser.

[0022] Optionally, the geothermal evaporation module adopts a closed-loop structure and is filled with a heat exchange medium; after absorbing geothermal energy underground, the heat exchange medium directly transforms into water vapor in situ, and the water vapor is sent into the catalytic reactor.

[0023] Optionally, the catalytic reactor includes:

[0024] Reaction chamber;

[0025] The catalyst bed is fixed inside the reaction chamber;

[0026] and at least one of the following:

[0027] A light source system is provided to the catalyst bed to provide the light energy required for the catalytic reaction; the light source system includes a concentrator for focusing natural light and / or an array of artificial light sources composed of LED lamps;

[0028] An electric field application device is used to provide the catalyst bed with the electric field required for the catalytic reaction;

[0029] A temperature control system is used to maintain the temperature of the catalyst bed within a preset range.

[0030] Optionally, the mixing condenser may be internally equipped with baffles, a packing layer, or a sieve plate to extend the gas-liquid contact path and time.

[0031] Optionally, the geothermal-assisted catalytic decomposition of water vapor to produce hydrogen also includes a temperature sensor for monitoring the temperature of the mixed gas at the outlet of the mixing condenser or the gas phase outlet of the gas-liquid separation unit.

[0032] The control unit is connected to the temperature sensor to obtain the temperature of the mixed gas at the outlet of the mixing condenser or the gas phase outlet of the gas-liquid separation unit. Using this temperature as a feedback signal, and combined with the gas product flow rate obtained by the flow sensor as a feedforward signal, the control valve is subjected to feedforward-feedback composite control.

[0033] Optionally, the water replenishment unit is connected to an external water source or water storage device.

[0034] Optionally, the liquid working medium filled in the geothermal evaporation module is water, or other liquid working medium that can generate hydrogen through catalytic reaction.

[0035] A method for producing hydrogen based on any of the above-described systems includes the following steps:

[0036] Geothermal evaporation steps: Using geothermal energy to heat liquid water, causing it to evaporate in situ underground to produce water vapor;

[0037] Catalytic reaction step: The water vapor is introduced into the catalytic reactor and decomposed into a mixed gas containing hydrogen and oxygen under the action of photocatalysis, electrocatalysis, photoelectric synergistic catalysis or photothermal synergistic catalysis;

[0038] Mixing, condensation, and water replenishment steps: Based on the gas product flow rate of the catalytic reactor, replenishment water of a corresponding flow rate is injected into the mixed gas to condense the water vapor in the mixed gas and mix it with the replenishment water;

[0039] Separation and reflux step: The condensate and hydrogen are separated, and the condensate and makeup water are refluxed back to the geothermal evaporation step for recycling;

[0040] Hydrogen collection steps: Collect the separated hydrogen.

[0041] Optionally, in the mixing condensation and water replenishment step, the replenishment water flow rate Q is dynamically adjusted using a feedforward-feedback composite control algorithm by the control unit. total The feedforward control quantity Q ff The method for determining it is as follows:

[0042] Obtain the flow rate of gaseous products G out Based on the water loss corresponding to the stoichiometric ratio of water decomposition and the basic heat exchange required for water vapor condensation, the feedforward control quantity Q is calculated. ff = K ff ·G out K ff The preset feedforward compensation coefficient;

[0043] The feedback control quantity Q fb The method for determining this is: real-time monitoring of the temperature T after the mixed gas condenses. real Calculate its relationship with the preset target temperature T. set The deviation e(t) is used to calculate the feedback control quantity Q using a PID algorithm. fb The control unit linearly superimposes the feedforward control quantity and the feedback control quantity to obtain Q. total = Q ff + Q fb The control valve opening is adjusted by outputting a signal based on this signal.

[0044] Compared with the prior art, the advantages of this invention are as follows:

[0045] (1) Multi-energy complementarity and cascade utilization of geothermal and solar energy: Geothermal energy is responsible for the stable generation of water vapor and heat, while solar energy (or electricity) is responsible for driving catalytic reactions. The two have a clear division of labor and complementary advantages. Geothermal energy makes up for the intermittent and unstable shortcomings of solar energy, while solar energy provides efficient catalytic excitation energy, realizing the deep coupling and cascade utilization of the two clean energy sources, and significantly improving the overall energy efficiency of the system.

[0046] (2) Stable and efficient water vapor supply: Geothermal evaporation module (e.g., ultra-long gravity heat pipe) is used to extract geothermal energy without pumps, and geothermal energy drives water evaporation, providing a stable, continuous and low-cost water vapor source for gas-solid decoupling catalytic reaction, overcoming the problems of high energy consumption of traditional electric heating and the great influence of weather on solar evaporation.

[0047] (3) Self-water replenishment and water balance maintenance: The water replenishment amount is precisely adjusted by the control unit according to the gas output to compensate for the water consumed by the water decomposition reaction. With the return of condensate, the water balance of the system is automatically maintained, eliminating the need for frequent manual water replenishment and ensuring long-term continuous and stable operation.

[0048] (4) No external heat / cold source required: High-temperature water vapor is generated by geothermal energy, and low-temperature supplementary water is used to directly cool the mixed gas after the reaction. At the same time, condensation and water replenishment are completed. There is no need to configure high-energy-consuming steam generators, cooling towers or condensers, which greatly simplifies the system structure and reduces energy consumption and equipment costs.

[0049] (5) Modular and scalable: Each part of the system (geothermal well, catalytic reactor module, mixing condenser, etc.) can be modularly designed and can be flexibly configured according to the scale of hydrogen production. It is suitable for small-scale single-well applications or large-scale hydrogen production scenarios of multiple wells and well groups. It can also be used to transform abandoned wells in oil fields and revitalize existing assets. Attached Figure Description

[0050] Figure 1 This is a schematic diagram of the hydrogen production system based on the synergy of geothermal and solar thermal energy in Embodiment 1 of the present invention.

[0051] In the diagram: 1. Geothermal evaporation module; 2. Catalytic reactor; 3. Mixing condenser; 4. Water replenishment unit; 5. Gas-liquid separation unit; 6. Return pipeline; 7. Gas collection unit; 8. Flow sensor; 9. Control unit; 10. Control valve; 11. Temperature sensor; 12. One-way exhaust valve; 13. Pressure control unit; 14. Pressure sensor.

[0052] Figure 2 The logical architecture of the control unit of the present invention reflects the process of the flow feedforward signal and the temperature feedback signal converging in the synthesizer (Summation Node); wherein, the upper feedforward branch solves the system water replenishment demand based on the law of conservation of mass; and the lower feedback branch solves the condensation accuracy demand based on the law of conservation of energy. Detailed Implementation

[0053] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0054] This application addresses the problems in existing technologies, such as unstable water vapor sources due to gas-solid decoupling, lack of efficient coupling between geothermal and solar energy, and the absence of active water replenishment and water balance maintenance mechanisms during long-term system operation. It provides a geothermal-assisted catalytic water vapor decomposition hydrogen production system, comprising:

[0055] Geothermal evaporation module 1 is used to absorb geothermal energy and convert liquid water into water vapor. Preferably, the geothermal evaporation module 1 can be an ultra-long gravity heat pipe, with the evaporation end located in the underground thermal reservoir and the condensation end connected to the inlet of the catalytic reactor 2. The ultra-long gravity heat pipe can efficiently utilize geothermal energy to evaporate catalytic reactants from liquid water into water vapor under "pump-free" conditions, and increase the reaction temperature, providing a stable, low-cost, and high-energy water vapor source for gas-solid decoupling catalytic reactions.

[0056] The catalytic reactor 2, whose inlet is connected to the outlet of the geothermal evaporation module 1, is used to receive the water vapor and decompose it into a mixed gas containing hydrogen and oxygen under photocatalysis, electrocatalysis, photoelectric synergistic catalysis, or photothermal synergistic catalysis. The catalytic reactor includes a reaction chamber, a catalyst bed, and at least one of the following: a light source system (such as a concentrator or LED array), an electric field application device, and a temperature control system to adapt to different catalytic modes.

[0057] The mixing condenser 3 has its inlet connected to the outlet of the catalytic reactor and is used to receive the mixed gas. The mixing condenser is equipped with a spray device (such as an atomizing nozzle) to spray low-temperature makeup water into the mixing condenser, allowing the makeup water to directly contact the high-temperature mixed gas, thereby achieving rapid condensation of water vapor. Preferably, the mixing condenser is also equipped with baffles, a packing layer, or a sieve plate to extend the gas-liquid contact path and time.

[0058] The water replenishment unit 4 is connected to the spray device inside the mixing condenser 3 via a pipeline equipped with a control valve 10, for spraying low-temperature replenishment water into the mixing condenser 3. The water replenishment unit 4 is connected to an external water source or a water storage device. Preferably, a water purification unit is also provided on the pipeline between the water replenishment unit and the mixing condenser to remove impurities from the replenishment water and prevent catalyst poisoning.

[0059] The gas-liquid separation unit 5 has its inlet connected to the outlet of the mixing condenser and is used to separate condensate from uncondensed hydrogen.

[0060] Return pipe 6 connects the water phase outlet of the gas-liquid separation unit to the inlet of the geothermal evaporation module, and is used to return the condensate and makeup water to the geothermal evaporation module to form an internal water circulation.

[0061] Gas collection unit 7, connected to the gas phase outlet of gas-liquid separation unit 5, is used to collect hydrogen. A one-way exhaust valve 12 is installed in the pipeline connecting gas collection unit 7 and gas-liquid separation unit 5.

[0062] In addition, to achieve self-replenishment of water and maintenance of water balance, the locally thermally assisted catalytic water splitting steam hydrogen production system also includes:

[0063] Flow sensor 8 is used to measure the flow rate of gaseous products in the catalytic reactor 2.

[0064] Control unit 9, connected to control valve 10 and flow sensor 8, adjusts the opening of control valve 10 according to the flow rate of the two gas products of the catalytic reactor, so as to control the flow rate of makeup water injected into the mixing condenser.

[0065] Temperature sensor 11 is used to monitor the temperature of the mixed gas at the outlet of the mixing condenser 3 or the gas phase outlet of the gas-liquid separation unit 5;

[0066] The control unit 9 is connected to the temperature sensor 11 and is used to obtain the temperature of the mixed gas at the outlet of the mixing condenser or the gas phase outlet of the gas-liquid separation unit. Using this temperature as a feedback signal, combined with the gas product flow rate obtained by the flow sensor as a feedforward signal, the control valve is subjected to feedforward-feedback composite control.

[0067] The control unit of this invention employs a feedforward-feedback composite control algorithm to address the problems of drastic changes in gas product flow and condensation lag caused by geothermal and solar radiation fluctuations. The specific steps are as follows:

[0068] 1. Parameter Acquisition and Signal Definition

[0069] The control unit acquires two core signals in real time:

[0070] Feedforward signal: Instantaneous mass flow rate G of gas and product at the catalytic reactor outlet, collected by a flow sensor. out (or volumetric flow rate Q) gas This signal reflects the system's immediate water consumption and the heat load to be cooled.

[0071] Feedback signal: The temperature T of the mixed gas at the outlet of the mixing condenser or the gas phase outlet of the gas-liquid separator, collected by a temperature sensor. real .

[0072] 2. Calculation of feedforward control variables (based on mass and energy balance prediction)

[0073] Feedforward control quantity Q ff The aim is to preemptively offset disturbances caused by changes in hydrogen production. The calculation model is as follows:

[0074] Q ff = K ff ·G out

[0075] Among them, K ff This is the feedforward compensation coefficient. In physical logic, K... ff The value is derived from two coupled parts: ① Consumption compensation term: based on the chemical reaction equation 2H2O → 2H2 + O2, it compensates for the amount of water consumed in the reaction. ② Heat load term: based on the heat transfer ratio between the latent heat of condensation of the mixed gas and the sensible heat of the makeup water, it estimates the amount of basic water required to cool to the target temperature.

[0076] 3. Feedback control quantity calculation (based on precise deviation correction)

[0077] Feedback control quantity Q fb Used to eliminate model errors and environmental disturbances (such as changes in external water source temperature). The target condensation temperature is set to T. set (Preferably 35°C - 50°C), calculate the temperature deviation e(t) = T set - T real And use the PID algorithm:

[0078] Among them, K p , K i , K d These are the proportional, integral, and differential coefficients, respectively.

[0079] 4. Synthesis and Execution of Total Control Quantities

[0080] The control unit linearly superimposes the feedforward and feedback control quantities to obtain the final execution control quantity Qtotal.

[0081] Q total = α·Q ff +β·Q fb

[0082] (Typically, weighting coefficients α = 1, β = 1 are used). The control unit will Q total Convert to a standard industrial electrical signal (such as 4-20mA) to adjust the opening of the water supply unit control valve.

[0083] The necessity of employing a feedforward-feedback composite control algorithm in this invention lies in the fact that geothermal evaporation modules (such as ultra-long gravity heat pipes) have significant thermal inertia, and the catalytic hydrogen production process is severely affected by external energy fluctuations such as light and electric fields. If conventional single-loop temperature feedback regulation is used, the system response suffers from severe lag, easily leading to the working fluid in the geothermal well drying out or excessive moisture content in the hydrogen at the outlet of the mixing condenser. This algorithm achieves real-time balance of 'how much hydrogen is produced and how much water is replenished' through the feedforward branch, preemptively offsetting more than 80% of heat load disturbances and ensuring that the system can maintain metastable operation even under drastically fluctuating production environments.

[0084] The present invention will now be described in detail with reference to specific embodiments. These embodiments are intended to illustrate implementation methods of the present invention under different catalytic modes and application scenarios, and are not intended to limit the scope of protection thereof.

[0085] Example 1 (Single well + photocatalytic or electrocatalytic mode)

[0086] System Configuration:

[0087] In a geothermal resource-rich area, a geothermal well is drilled, and a geothermal evaporation module (such as an ultra-long gravity heat pipe) is installed inside the well. The heat absorption end of the evaporator is located in the underground thermal reservoir, and the steam outlet is connected to the inlet of the catalytic reactor.

[0088] The catalytic reactor can be selected from one of the following two configurations according to actual needs:

[0089] (1) Photocatalytic configuration: A light-transmitting reaction chamber is used, filled with a photocatalyst (such as TiO2 or g-C3N4). The light source system uses an LED array or focused natural light to provide illumination for the catalyst. No electric field application device or active heating system is set up, and the reaction is carried out at near room temperature.

[0090] (2) Electrocatalytic configuration: A non-transparent reaction chamber is used, filled with an electrocatalyst (such as Pt / C, NiFe-LDH, RuO2). Electrodes are placed on both sides of the catalyst bed and connected to a power source. A temperature control system can be set up as needed to maintain the optimal reaction temperature. No light source system is provided.

[0091] The mixing condenser is equipped with atomizing nozzles, and the water supply unit is connected to an external water source. The control valve is regulated by the control unit. The aqueous phase outlet of the gas-liquid separation unit is connected to the inlet of the geothermal evaporation module via a return pipeline.

[0092] System operation:

[0093] The geothermal evaporation module extracts geothermal energy to generate water vapor, which then enters the catalytic reactor. In a photocatalytic configuration, the photocatalyst decomposes the water vapor into hydrogen and oxygen under illumination; in an electrocatalytic configuration, the electrocatalyst decomposes the water vapor into hydrogen and oxygen under the influence of an electric field. The control unit adjusts the amount of water injected based on the gas production to achieve condensation, water replenishment, and water balance.

[0094] To address the vertical heat transfer requirements at depths of kilometers, quantitative verification of key dimensionless numbers Ku (Kuttatrazee number) and We (Weber number) ensures that the gas-liquid two-phase flow inside the pipe remains in a stable counter-current annular flow pattern, preventing heat transfer interruptions due to carryover limits. Simultaneously, the low-temperature water injected by the makeup water unit, after condensing the mixed gas, carries some of the waste heat back to the heat pipe's absorber section, achieving cascaded utilization of thermal energy.

[0095] In practical engineering applications, this system mainly relies on the hydrostatic pressure head of the liquid column generated at a vertical depth of kilometers and the local condensation negative pressure generated by the sprayed water in the mixing condenser to achieve the self-driven circulation of the working fluid. However, considering the local resistance and frictional resistance caused by the catalyst bed, gas-liquid separation unit, bends and long-distance pipelines within the system at the kilometer scale, this system can be further configured with a pressure compensation mechanism when necessary.

[0096] Specifically, this system can selectively install a pressure control unit 13 (such as a liquid phase booster pump) in the return pipeline, or a gas phase exhaust fan in the gas phase loop. The pressure control unit 13 is electrically connected to the control unit 9. When the system starts up or experiences severe fluctuations in operating conditions leading to insufficient circulating power, the control unit 13 dynamically adjusts its power based on the real-time pressure difference monitored by the internal pressure sensor 14.

[0097] This design, characterized by "self-drive as the primary mode and active control as a secondary mode," ensures that the working fluid, after overcoming the pressure drop in the catalytic reactor and the resistance of gas-liquid separation, still possesses sufficient kinetic energy to flow back to the geothermal evaporation module. Through this flexible pressure regulation method, the system can adapt to geothermal well conditions at different depths and effectively prevent circulation stagnation caused by the accumulation of non-condensable gas or excessive resistance, significantly improving the system's operational stability in extreme geological environments.

[0098] This embodiment is applicable to scenarios with abundant geothermal resources, and the photocatalytic or electrocatalytic mode can be flexibly selected according to sunshine conditions and power supply. Among them, the electrocatalytic mode is particularly suitable for scenarios with insufficient sunshine or requiring stable hydrogen production, and can utilize off-peak electricity or renewable energy power.

[0099] Example 2 (Well Cluster + Photoelectrochemical Synergistic Catalysis Mode)

[0100] System Configuration:

[0101] A well group is formed by multiple geothermal wells, and geothermal evaporation modules (such as ultra-long gravity heat pipes) are installed in each well. The steam is collected into a common header and then distributed to multiple catalytic reactor modules.

[0102] The catalytic reactor employs a light-transmitting reaction chamber filled with a photocatalyst (such as TiO2 or BiVO4). Electrodes are positioned on both sides of the catalyst bed and connected to a power source for applying a bias voltage. The light source system uses a linear Fresnel focusing system or an LED array. No active heating is employed.

[0103] The water replenishment unit is connected to the plant's water storage tank. The control unit adopts a distributed control system to monitor the steam parameters and gas output of each module in real time and dynamically allocate the water replenishment amount.

[0104] System operation:

[0105] The water vapor generated by the well cluster is distributed to each reactor module. Under the synergistic effect of sunlight and an electric field, photogenerated electrons are driven to migrate by the electric field, inhibiting recombination and improving decomposition efficiency. The control unit adjusts the water supply according to the total gas production and the operating status of each module. This embodiment is suitable for large-scale hydrogen production and can improve efficiency through electric field compensation when sunlight is insufficient.

[0106] Example 3 (Abandoned oilfield wells + photothermal synergistic catalysis mode)

[0107] System Configuration:

[0108] Abandoned wells in decommissioned oilfields are selected, cleaned, and repaired before being installed with geothermal evaporation modules (e.g., ultra-long gravity heat pipes). Thermally conductive material is filled between the evaporator and the well wall. The steam outlet is connected to a catalytic reactor. For clusters of abandoned wells, a parallel configuration is used, with steam collected and distributed to multiple reactor modules.

[0109] The catalytic reactor employs a quartz glass reaction chamber filled with a photothermal synergistic catalyst (such as aluminum-doped strontium titanate). The light source system uses a parabolic trough concentrator to focus sunlight onto the reactor, providing both photoexcitation and heating. An insulation layer is installed around the reactor, and auxiliary electric heating is optional.

[0110] System operation:

[0111] Abandoned wells extract geothermal energy to generate water vapor, which enters a catalytic reactor. A concentrating system heats the catalyst bed to a suitable temperature (e.g., 200-400°C), while photogenerated charge carriers participate in the reaction, resulting in efficient decomposition of the water vapor under the synergistic effect of photothermal activity. The control unit adjusts the water replenishment based on the gas production. This embodiment significantly reduces drilling costs and realizes the resource utilization of abandoned wells.

[0112] The above embodiments use water as the working medium. However, those skilled in the art will understand that other hydrogen-containing liquid working media such as ethanol and methanol can also be used in geothermal evaporation modules to generate hydrogen through catalytic reforming reactions. The system structure and operating principle are basically the same as when water is used as the working medium. The above descriptions are merely preferred embodiments of the present invention, intended to illustrate implementation methods under different catalytic modes and application scenarios. For those skilled in the art, several modifications and improvements can be made without departing from the spirit and principles of the present invention, and these modifications and improvements should also be considered within the scope of protection of the present invention.

Claims

1. A geothermal-assisted catalytic water vapor decomposition hydrogen production system, characterized in that, include: Geothermal evaporation module is used to absorb geothermal energy and convert liquid water into water vapor; A catalytic reactor, whose inlet is connected to the outlet of the geothermal evaporation module, is used to receive the water vapor and decompose the water vapor into a mixed gas containing hydrogen and oxygen. A mixing condenser, the inlet of which is connected to the outlet of the catalytic reactor, is used to receive the mixed gas; A water replenishment unit is connected to the mixing condenser via a pipeline with a control valve to spray replenishment water into the mixing condenser to cool and partially condense the water vapor in the mixed gas. A gas-liquid separation unit, the inlet of which is connected to the outlet of the mixing condenser, is used to separate condensate from uncondensed hydrogen. A return pipeline connects the aqueous phase outlet of the gas-liquid separation unit to the inlet of the geothermal evaporation module, and is used to return the condensate and makeup water to the geothermal evaporation module. A gas collection unit, connected to the gas phase outlet of the gas-liquid separation unit, is used to collect hydrogen gas.

2. The geothermal-assisted catalytic water vapor decomposition hydrogen production system as described in claim 1, characterized in that, Also includes: A flow sensor is used to measure the flow rate of the gaseous products in the catalytic reactor; A control unit, connected to the control valve and flow sensor, adjusts the opening of the control valve according to the gas product flow rate of the catalytic reactor to control the flow rate of makeup water injected into the mixing condenser.

3. The geothermal-assisted catalytic water vapor decomposition hydrogen production system as described in claim 1, characterized in that, The geothermal evaporation module adopts a closed-loop structure and is filled with a heat exchange medium. After absorbing geothermal energy underground, the heat exchange medium directly transforms into water vapor in situ, and the water vapor is sent into the catalytic reactor.

4. The geothermal-assisted catalytic water vapor decomposition hydrogen production system as described in claim 1, characterized in that, The catalytic reactor includes: Reaction chamber; The catalyst bed is fixed inside the reaction chamber; and at least one of the following: A light source system is provided to the catalyst bed to provide the light energy required for the catalytic reaction; the light source system includes a concentrator for focusing natural light and / or an array of artificial light sources composed of LED lamps; An electric field application device is used to provide the catalyst bed with the electric field required for the catalytic reaction; A temperature control system is used to maintain the temperature of the catalyst bed within a preset range.

5. The geothermal-assisted catalytic water vapor decomposition hydrogen production system as described in claim 1, characterized in that, The internal structure of the mixing condenser is equipped with baffles, packing layers, or sieves to extend the gas-liquid contact path and time.

6. The geothermal-assisted catalytic water vapor decomposition hydrogen production system as described in claim 2, characterized in that, It also includes a temperature sensor for monitoring the temperature of the mixed gas at the outlet of the mixing condenser or the gas phase outlet of the gas-liquid separation unit; The control unit is connected to the temperature sensor to obtain the temperature of the mixed gas at the outlet of the mixing condenser or the gas phase outlet of the gas-liquid separation unit. Using this temperature as a feedback signal, and combined with the gas product flow rate obtained by the flow sensor as a feedforward signal, the control valve is subjected to feedforward-feedback composite control.

7. The geothermal-assisted catalytic water vapor decomposition hydrogen production system as described in claim 1, characterized in that, The water replenishment unit is connected to an external water source or water storage device.

8. The geothermal-assisted catalytic steam decomposition hydrogen production system as described in claim 1, characterized in that, The liquid working medium filled in the geothermal evaporation module is water, or other liquid working medium that can generate hydrogen through catalytic reaction.

9. A method for producing hydrogen based on the system according to any one of claims 1 to 6, characterized in that, Includes the following steps: Geothermal evaporation steps: Using geothermal energy to heat liquid water, causing it to evaporate in situ underground to produce water vapor; Catalytic reaction step: The water vapor is introduced into the catalytic reactor and decomposed into a mixed gas containing hydrogen and oxygen under the action of photocatalysis, electrocatalysis, photoelectric synergistic catalysis or photothermal synergistic catalysis; Mixing, condensation, and water replenishment steps: Based on the gas product flow rate of the catalytic reactor, replenishment water of a corresponding flow rate is injected into the mixed gas to condense the water vapor in the mixed gas and mix it with the replenishment water; Separation and reflux step: The condensate and hydrogen are separated, and the condensate and makeup water are refluxed back to the geothermal evaporation step for recycling; Hydrogen collection steps: Collect the separated hydrogen.

10. The hydrogen production method as described in claim 9, characterized in that, In the mixing condensation and water replenishment step, the replenishment water flow rate Q is dynamically adjusted by the control unit using a feedforward-feedback composite control algorithm. total The feedforward control quantity Q ff The method for determining it is as follows: Obtain the flow rate of gaseous products G out Based on the water loss corresponding to the stoichiometric ratio of water decomposition and the basic heat exchange required for water vapor condensation, the feedforward control quantity Q is calculated. ff = K ff ·G out K ff The preset feedforward compensation coefficient; The feedback control quantity Q fb The method for determining this is: real-time monitoring of the temperature T after the mixed gas condenses. real Calculate its relationship with the preset target temperature T. set The deviation e(t) is used to calculate the feedback control quantity Q using a PID algorithm. fb The control unit linearly superimposes the feedforward control quantity and the feedback control quantity to obtain Q. total = Q ff + Q fb The control valve opening is adjusted by outputting a signal based on this signal.

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