A biogas hydrogen production and alkaline water electrolysis hydrogen production coupled hybrid hydrogen production system

Abstract

This invention discloses a hybrid hydrogen production system that couples biogas hydrogen production with alkaline water electrolysis hydrogen production. It comprises an energy feedstock module, a biogas conversion (BSMR) hydrogen production module, an alkaline water electrolysis (ALK) hydrogen production module, and a pressure swing adsorption (PSA) hydrogen extraction module. Its key feature is its ability to provide a highly efficient hybrid hydrogen production system that couples BSMR biogas hydrogen production with ALK water electrolysis hydrogen production, achieving high energy transfer, conversion efficiency, and energy balance in the process of producing hydrogen with a purity greater than or equal to 99.99% from renewable biomass biogas and water. This system can automatically switch between hydrogen production modules based on resource supply conditions. It leverages the advantages of BSMR biogas conversion hydrogen production (byproduct steam) and ALK water electrolysis hydrogen production (requiring heating and producing byproduct oxygen), as well as the low-cost advantage of direct biogas power generation as a backup for ALK hydrogen production. By regulating the hydrogen feedstock structure and including both in-station and centralized hydrogen supply modes, it overcomes the shortcomings of individual BSMR and ALK hydrogen production, transforming them into a combined advantage and reducing hydrogen production costs.

Description

Technical Field

[0001] This invention belongs to the field of hydrogen production technology in hydrogen energy, and in particular relates to a hybrid hydrogen production system that couples biogas hydrogen production with alkaline water electrolysis hydrogen production. Background Technology

[0002] Hydrogen energy is one of the most promising clean energy sources. However, it is categorized into "gray hydrogen" and "green hydrogen" based on whether the hydrogen production process emits pollutants. "Gray hydrogen" is primarily produced from fossil fuels containing hydrocarbons through catalytic thermal cracking, reforming, and hydrocarbon separation, releasing CO2, CO, or other pollutants. Raw materials include natural gas, methanol, coal, and heavy oil. Steam reforming (SMR) of natural gas is currently the world's largest, most mature, and lowest-cost method for producing gray hydrogen. "Green hydrogen" is typically produced through water electrolysis. The entire process is essentially zero-emission, except for the production of oxygen as a byproduct. However, water electrolysis requires significant energy consumption (electricity), leading to higher costs and limiting its suitability to small-scale production. Biogas is a renewable biomass resource, currently most commonly used as fuel gas and for power generation. With the development of biogas-to-hydrogen (BSMR) technology, the steam reforming and conversion of biogas as an inexpensive feedstock to produce hydrogen has become a typical example of small-scale hydrogen production.

[0003] The publicly disclosed patent for biogas-based hydrogen production—"A Method for Hydrogen Production from Biogas (CN107758617A)"—is representative of biogas-based hydrogen production (BSMR). The entire hydrogen production process mainly includes four major steps: pre-purification, concentration, hydrogen production, and hydrogen extraction. The raw biogas, after pre-purification and desulfurization, is pressurized and enters a pressure swing adsorption (PSA) concentration unit. This is because, besides the main component methane, biogas is mostly CO2, with a concentration typically between 30% and 40%. Therefore, the methane needs to be concentrated. The concentrated gas is then pressurized and preheated before further desulfurization in a fine desulfurization tower. The intermediate gas after fine desulfurization, along with process steam, is further preheated and enters a conversion furnace. Methane reacts with steam to produce converted gas containing CO, CO2, and H2. The residual heat can be used as byproduct steam for external export. Through multi-stage heat recovery, a medium-temperature conversion process converts CO to CO2 to obtain more hydrogen and improve the hydrogen yield. After conversion, the gas undergoes multi-stage heat recovery and cooling before entering the pressure swing adsorption (PSA) hydrogen extraction process to obtain H2 product gas with a purity of ≥99.99%, while also producing steam as a byproduct. The concentration process concentrates methane, achieving a single-pass yield of over 95%. The remaining effective components are recovered and reused in the tail gas to provide heat energy for the unit. Thus, the total methane utilization rate is almost 100%, achieving full recovery. Because biogas is relatively inexpensive and a renewable biomass resource, the price of the obtained H2 product gas is much lower compared to hydrogen production from other fossil resources. 3Biogas production is approximately 1 Nm³ 3 The H2 product gas from biogas is produced. However, biogas-to-hydrogen also has some significant drawbacks: First, greenhouse gas CO2 is generated at several points during the biogas-to-hydrogen process, such as desorption gas from biogas concentration, methane steam reforming, wet decarbonization or dry PSA hydrogen extraction processes, and flue gas emissions. A large amount of CO2 is difficult to utilize comprehensively, so the H2 product gas produced by biogas-to-hydrogen technology is essentially still "gray hydrogen." Moreover, the larger the scale of hydrogen production, the more CO2 is generated, making it environmentally unfriendly. Second, biogas-to-hydrogen produces but does not emit CO2, meaning the emitted CO2 is subject to carbon capture and storage. This carbon capture and storage process incurs costs, resulting in H2 product gas called "blue hydrogen," which is far more expensive than "gray hydrogen." Third, the hydrogen production through conversion in published biogas-to-hydrogen patents essentially uses natural gas as a raw material. Similar to steam reforming (SMR) for hydrogen production, the reformer typically provides the heat required for the reforming process through a combustion chamber and radiant section of the raw natural gas located at the top of the furnace and a convection section located at the bottom of the furnace. Waste heat is used to generate steam output, resulting in a heat imbalance in the system. Furthermore, it consumes raw natural gas as fuel. Hydrogen production from biogas requires the consumption of biogas or concentrated methane, increasing energy consumption. At the same time, the consumption of raw natural gas results in increased emissions of flue gas (containing a large amount of CO2), and more heat exchange is required to cool the flue gas, leading to wasted H2 production. Fourth, the biogas hydrogen production process is relatively long, and the radiant reformer and compressor unit occupy a relatively large area and volume. In particular, the compressor safety distance required for high pressure, the radiant reformer in the reforming section, and the multiple PSA adsorption towers in the separation and purification section make it difficult to form a small skid-mounted unit and build it directly in the hydrogen refueling station.

[0004] "Green hydrogen" is produced using renewable energy sources (such as geothermal, ocean energy, wind power, photovoltaic solar energy, as well as solid waste and biomass). The hydrogen production process is completely carbon-free. Water electrolysis is the main method for producing "green hydrogen," a necessary technology for hydrogen energy development, and a crucial pillar for achieving the "dual carbon" goal. Water electrolysis is an electrochemical process that decomposes water into hydrogen (H2) and oxygen (O2). Currently, hydrogen production through water electrolysis is classified into three types based on the type of electrolysis membrane: alkaline water electrolysis (ALK or AWE), proton exchange membrane electrolysis (PEM), and solid oxide electrolysis (SOEC). Among these, alkaline water electrolysis (ALK) is the most widely used industrial method for hydrogen production. It is low-cost and has a simple setup. The electrolyte is a 25-30% KOH or NaOH solution. In this method, O2 with a purity of 99.2% is produced at the anode as a byproduct gas, while H2 (industrial-grade hydrogen) with a purity of up to 99.8% is produced at the cathode. After heating to 120-160℃, H2 undergoes chemical catalytic deoxygenation, followed by heat exchange cooling and adsorption drying, resulting in a H2 purity of over 99.999%. The electrolytic cell operates at a temperature of 70–90℃, with an energy consumption of 4.0–5.5 kW·h / Nm³. 3 • H2, system conversion efficiency 50-75%, single tank H2 production capacity can reach up to 2000 Nm³ 3 / h, minimum is 0.4Nm 3 / h, especially suitable for on-site hydrogen production in hydrogen refueling stations, with small footprint and no pollution. However, alkaline water electrolysis for hydrogen production has several significant drawbacks: First, the electrolysis efficiency is low, ranging from 50% to 75%, while the overall hydrogen production efficiency is only 25% to 35%, with the remaining efficiency used to produce the byproduct O2. It is also the least efficient of the three main water electrolysis hydrogen production processes. Second, it has high energy consumption, leading to high hydrogen production costs. The energy consumption (electricity) of the electrolyzer alone is higher than that of the entire natural gas steam SMR conversion hydrogen production system. Furthermore, areas near hydrogen refueling markets generally experience power shortages and high electricity prices, further increasing the cost of hydrogen production. Third, the electrolyzer itself operates at 70-90°C, requiring thermal energy. The 99.8% pure H2 obtained from the electrolyzer needs to undergo purification processes such as heating for deoxygenation and cooling for drying. These purification steps further increase energy consumption and waste, resulting in high energy consumption for the water electrolysis hydrogen production system. Fourth, water electrolysis hydrogen production also exhibits economies of scale. While small skid-mounted water electrolysis hydrogen production systems are readily available for hydrogen refueling stations, they are typically smaller than 100 Nm. 3 A hydrogen production facility with a capacity of [number] h consumes more energy and has a higher cost. This is the main reason why hydrogen production through water electrolysis at hydrogen refueling stations cannot be fully promoted both domestically and internationally at present. Summary of the Invention

[0005] To address the problems inherent in purely biogas-based hydrogen production (BSMR) and alkaline water electrolysis (ALK) technologies, the primary objective of this invention is to provide a compact and efficient hybrid hydrogen production system that combines BSMR and ALK technologies. This system is characterized by its compact and efficient energy transfer, conversion efficiency, and energy balance, and its ability to automatically switch between modular hydrogen production based on the availability of biogas resources from the nearby H2 market and grid resources. Specifically, it is a hybrid hydrogen production system that couples biogas-based hydrogen production with alkaline water electrolysis. This system fully utilizes the advantages of BSMR biogas-based hydrogen production byproduct steam and ALK water electrolysis hydrogen production byproduct oxygen and demineralized water requiring heating. It also leverages direct biogas power generation as a backup for ALK hydrogen production, regulates the hydrogen feedstock structure, and incorporates both in-station and centralized hydrogen supply modes. This overcomes the individual shortcomings of BSMR and ALK hydrogen production, transforming them into a combined advantage. This results in reduced hydrogen production costs while increasing "green hydrogen" output and decreasing the proportion of "grey hydrogen." To this end, the following technical solution is proposed.

[0006] 1. A hybrid hydrogen production system coupling biogas hydrogen production and solid oxide water electrolysis hydrogen production, characterized in that,

[0007] The hybrid hydrogen production system consists of an energy feedstock module, an alkaline water electrolysis (ALK) hydrogen production module, a biogas conversion (BSMR) hydrogen production module, a pressure swing adsorption (PSA) hydrogen extraction module, and pipelines, valves, and heat exchangers connecting these modules. The energy feedstock module is responsible for pretreatment of biogas feedstock, including methane concentration, biogas power generation, and the treatment of process water, boiler water, and process steam. It optimizes the composition and energy of each feedstock to meet the requirements of downstream modules, including biogas or concentrated methane used as feedstock and fuel gas in the BSMR hydrogen production module, and P... The SA hydrogen extraction module produces H2-containing desorbed gas as supplementary fuel gas; the ALK hydrogen production module produces pure oxygen gas; hydrogenation gas and demineralized water storage tanks; ambient temperature or heaters or heat exchangers; atmospheric pressure or booster compressors; desulfurization of methane concentrate gas and treatment of process steam and mixed steam; biogas generators or hydropower or other power supply; demineralization pretreatment and heat exchange of process water and boiler water; and process raw materials, pure oxygen fuel, power grid inlet and outlet pipelines and control valves inside and outside the module; the ALK hydrogen production module mainly consists of one or more alkaline water electrolyzers connected in series / parallel. The BSMR hydrogen production module mainly consists of a gas-liquid processor, rectifier, electric heater, control system, water pump, alkali tank, water tank, and power, hydrogen (H2), and oxygen (O2) gas pipelines and process (hot / cold) water pipelines and control valves connecting the module internally and externally; the module mainly includes a preheating converter for mixed steam formed by mixing desulfurized methane concentrate gas and water vapor, an SMR converter / reactor with a combustion chamber at the top and convection and radiation sections at the bottom, a medium-high temperature shift reactor, a gas-liquid separator, a heat exchanger, a steam drum, a waste heat boiler, and modules. The system includes internally and externally connected pipelines for mixed steam, pre-converted gas, converted gas, shift gas, fuel gas, PSA hydrogen extraction and desorption gas, demineralized water, boiler feedwater, steam storage tanks, circulating water pipelines, deaerators, conveying and circulating pumps, and control valves. The PSA hydrogen extraction module consists of multiple series / parallel adsorption towers, a desorption gas buffer tank, and internally and externally connected pipelines for power supply, H2 product gas / desorption gas, H2 from the ALK hydrogen production module, shift gas from the BSMR hydrogen production module, and programmable control valves and regulating valve groups. The specific process is as follows:

[0008] (1) Energy feedstock module: Biogas from anaerobic fermentation is used as feedstock gas and is fed into the dry or wet desulfurization pre-purification process via a blower. The pre-purified biogas is then pressurized by a compressor.

[0009] The gas enters the PSA methane concentration system at a pressure of 0.6–1.0 MPa. This system consists of multiple adsorption towers connected in series / parallel and loaded with fixed adsorbent beds primarily composed of carbon molecular sieves. The desorbed gas generated during vacuum desorption is directly discharged. The resulting concentrated methane gas has a methane content of ≥92%. This concentrated gas is then pressurized to 1.0–4.0 MPa and preheated to 250–380°C before entering the hydrodesulfurization process. H2 from the ALK hydrogen production module serves as the hydrogen source. The purified concentrated methane gas after desulfurization is mixed with medium- and low-pressure process steam from the BSMR hydrogen production module. Steam is mixed to form a natural gas-water vapor mixture, which enters the BSMR hydrogen production module. Raw biogas or concentrated purified methane gas from within the module, O2 from the ALK hydrogen production module, or air from outside the boundary, as well as desorbed gas from the PSA hydrogen extraction module, are used as fuel gas or supplementary fuel gas. These gases enter the combustion chamber of the BSMR hydrogen production module for combustion, providing heat for the catalytic conversion reaction within the BSMR converter / reactor. Water from municipal tap water or industrial water, part of which is desalinated and preheated to 70–90°C by desalination, is used for the remaining portion. Demineralized water is fed into the water tank of the ALK hydrogen production module. Part of it is used as process water and enters the deaerator of the BSMR hydrogen production module. It then passes through the hot water pump, the steam boiler to form demineralized steam, and the convection section of the converter to form process steam. The process steam of the energy feedstock module is mixed with purified methane concentrate to form mixed steam, which then enters the BSMR hydrogen production module. Part of the demineralized water, which has not been preheated, is used as cooling water to cool the BSMR hydrogen production module. The cooled water is returned as process circulating water for reuse. The exhaust gas from the BSMR hydrogen production module and the ALK hydrogen production module undergoes heat exchange and gas-liquid separation. The water is returned for pretreatment, and the gas is discharged. Electricity from biogas power generation, urban power grid, or industrial power grid is directly connected to the control system of the ALK hydrogen production module to provide the power required for water electrolysis hydrogen production and the start-up or independent operation of the electric heater. Alternatively, on-site power generation equipment or peak-shaving power, including direct biogas power generation, pipeline natural gas power generation, hydropower station, and cogeneration, can be used to provide power to the ALK hydrogen production module. Among them, direct biogas power generation provides sufficient power for the miniaturized skid-mounted hydrogen production equipment of the on-site hydrogen refueling station.

[0010] (2) ALK hydrogen production module: When the power input from the energy feedstock module is connected to the control system consisting of a transformer and a control cabinet, the process water and alkali solution from the water tank and alkali tank flow into the electrolyzer through the alkali solution separator and alkali solution circulation pump. The operating temperature of the electrolyzer is 70-90℃. O2 with a concentration of 98.5-99.2% and a pressure of 1.0-2.0MPa is released from the anode of the electrolyzer and enters the oxygen storage tank. It is then output as fuel gas into the BSMR hydrogen production module. H2 with a concentration of 99.0-99.8% and a pressure of 1.0-2.0MPa is released from the cathode of the electrolyzer. After water is removed by the water-gas separator, part of it directly enters the PSA hydrogen extraction module to prepare H2 product gas, and part of it serves as the H2 source for the hydrogenation and desulfurization of methane concentrate in the energy feedstock module of the original energy feedstock module.

[0011] (3) In the BSMR hydrogen production module, purified methane concentrate from the energy feedstock module is mixed with steam and preheated by a convection preheater before entering the reforming conversion (SMR) tubular reformer / reactor of the BSMR hydrogen production module for reforming conversion reaction. The reformer or reactor tubes are filled with nickel / nickel-based catalysts. The mixed steam flows through the catalyst bed in the tubes for conversion reaction at a temperature of 700–950℃ and a pressure of 1.0–4.0 MPa. The converted gas generated from the conversion reaction is then heat-exchanged in the waste heat exchanger before entering the medium-high temperature shift reactor at a temperature of 300–500℃ and a pressure of 1.0–4.0 MPa. After the medium-high temperature shift reaction, the converted gas forms shift gas with a composition of 70–85% H2 and 13–28% carbon dioxide (CO2). The converted gas contains less than 1% carbon monoxide (CO), unreacted methane (CH4), and other trace hydrocarbon impurities. After heat exchange with boiler feedwater and demineralized water, the converted gas enters the PSA hydrogen extraction module for hydrogen extraction. The heat required for the reaction in the converter / reactor is obtained by using crude purified biogas or purified methane concentrate gas from the energy feedstock module (excluding feed gas) as fuel gas, which is mixed with O2 from the ALK hydrogen production module and desorbed gas from the PSA hydrogen extraction module, or air from outside the system, and then enters the BSMR hydrogen production module for combustion reaction. The high-temperature flue gas obtained from the combustion reaction in the burners at the top, bottom, or sides of the converter flows outside the tubes and is obtained through radiative heat transfer. The high-temperature flue gas is used as the heat source for the preheater, process steam, and waste heat boiler, and is discharged as flue gas after heat exchange, cooling, and treatment.

[0012] (4) PSA hydrogen extraction module: H2 with a purity of 99.0-99.8% from the ALK hydrogen production module and catalytically deoxygenated, and shift gas with an H2 concentration of 70-85% from the BSMR hydrogen production module are separately or mixed and enter a pressure swing adsorption (PSA) system consisting of at least three or more composite bed adsorption towers / devices loaded with adsorbent, connected in series or parallel or in series-parallel, and connected by pipelines, program control valves and regulating valve groups between the adsorption towers / devices. The adsorption pressure is 0.8-3.8 MPa and the adsorption temperature is 20-80℃. The adsorption towers / devices alternately switch to perform adsorption and desorption cycle operations including adsorption, pressure equalization, forward release, reverse release, vacuum / rinsing, and final charging steps, thereby obtaining H2 product gas with a purity greater than or equal to 99.99% which enters the H2 product gas tank. The desorbed gas obtained enters the buffer tank and is returned to the BSMR hydrogen production module for recycling as supplementary fuel gas. Thus, the total yield of H2 product gas is greater than or equal to 85%.

[0013] Furthermore, the hybrid hydrogen production system coupling biogas hydrogen production and alkaline water electrolysis hydrogen production is characterized in that the ratio between the H2 produced by the ALK hydrogen production module with a purity of 99.0-99.8% and catalytically deoxygenated and the shift gas with an H2 concentration of 70-85% produced by the BSMR hydrogen production module is 4-8:2-6. This ratio is adjusted by regulating the usage of demineralized water / process steam, and the amount of O2 in the feedstock and fuel biogas / ALK hydrogen production module / desorption gas / make-up air in the PSA hydrogen extraction module.

[0014] Furthermore, the hybrid hydrogen production system coupling biogas hydrogen production and alkaline water electrolysis hydrogen production is characterized in that the ALK hydrogen production module and the BSMR hydrogen production module operate independently by switching on and off the connection between the demineralized water / process steam, the feedstock / fuel biogas and the desorption gas pipeline and the logistics pipeline of the O2 / PSA hydrogen extraction module of the ALK hydrogen production module. The H2 product gas output of the PSA hydrogen extraction module depends on the maximum capacity of the ALK hydrogen production module and the BSMR hydrogen production module to produce H2 with a purity of 99.0–99.8% and shift gas with an H2 concentration of 70–85%, respectively.

[0015] Furthermore, the hybrid hydrogen production system coupling biogas hydrogen production and alkaline water electrolysis hydrogen production is characterized in that the hybrid hydrogen production system produces H2 product gas with a capacity of 100–20,000 Nm³. 3 / h, wherein the hydrogen production capacity of the ALK hydrogen production module is 20–12,000 Nm³. 3 / h, operating flexibility 70-100%, BSMR hydrogen production module 80-16,000 Nm 3 / h, with operational flexibility of 40-100%, the PSA hydrogen extraction module is...

[0016] 20~20,000Nm 3 / h, with operational flexibility of 30-110%.

[0017] Furthermore, the hybrid hydrogen production system coupling biogas hydrogen production and alkaline water electrolysis hydrogen production is characterized in that the converter / reactor of the BSMR hydrogen production module is filled with a low-temperature conversion catalyst, the conversion reaction temperature is 400-600℃, and the conversion reaction pressure is adjusted to 0.2-0.8MPa. The biogas feedstock gas in the energy feedstock module is conveyed under pressure by a blower without the need for pressurization. Simultaneously, biogas is not used as fuel gas; instead, desorbed gas from the PSA hydrogen extraction module and O2 from the ALK hydrogen production module are used as combustion gas. The H2 product gas yield is greater than 88%. This system is suitable for miniaturized skid-mounted hybrid hydrogen production systems with a hydrogen production capacity of 100-1000 Nm³. 3 / h.

[0018] Furthermore, the hybrid hydrogen production system coupling biogas hydrogen production and alkaline water electrolysis hydrogen production is characterized in that the converter / reactor of the BSMR hydrogen production module is filled with a bifunctional conversion and shift catalyst. As a result, the CO content in the converted gas flowing out of the converter / reactor of the BSMR hydrogen production module is less than 3-5%, and it can directly enter the PSA hydrogen extraction module without undergoing a medium-high temperature shift reaction. In this case, the composite adsorbent filled in the PSA adsorption tower / reactor must have an increased amount of proprietary CO molecular sieve.

[0019] Furthermore, the hybrid hydrogen production system coupling biogas hydrogen production and alkaline water electrolysis hydrogen production is characterized in that the H2 produced by the ALK hydrogen production module with a purity of 99.0-99.8% and catalytically deoxygenated, and the shift gas with an H2 concentration of 70-85% produced by the BSMR hydrogen production module, or a mixture thereof, are introduced into the feed inlet of one or more adsorption towers / recorders in the PSA hydrogen extraction module, or when the adsorption towers / recorders in the PSA hydrogen extraction module adopt two-stage adsorption, the shift gas from the BSMR hydrogen production module... The gas first enters a first-stage PSA decarbonization (CO2) consisting of at least three adsorption towers / units. The decarbonized shift gas flowing out from this stage is then mixed with H2 produced by the ALK hydrogen production module with a purity of 99.0-99.8% and catalytically deoxygenated, and then enters a second-stage PSA purification consisting of at least four adsorption towers / units to obtain H2 product gas. The first-stage desorption gas flowing out from the first-stage PSA decarbonization stage is directly emitted as flue gas, while the second-stage desorption gas flowing out from the second-stage PSA purification stage is returned to the BSMR hydrogen production module as supplementary fuel gas for recycling.

[0020] Furthermore, the hybrid hydrogen production system coupling biogas hydrogen production and alkaline water electrolysis hydrogen production is characterized in that the program control valves and regulating valve groups connected to each adsorption tower / recorder in the PSA methane concentration system and PSA hydrogen extraction module of the energy feedstock module are each replaced by a multi-channel rotary valve. The inlet and outlet of each adsorption tower / recorder in the PSA methane concentration and PSA hydrogen extraction systems are connected to the inlet and outlet of the upper and lower plates of the multi-channel rotary valve. The gas entering and exiting the PSA methane concentration system and PSA hydrogen production module includes purified biogas, purified methane concentrate gas / from AL... The H2 produced by the K hydrogen production module has a purity of 99.0-99.8% and is catalytically deoxygenated. It, along with the shift gas with an H2 concentration of 70-85% produced by the BSMR hydrogen production module, the H2 product gas flowing out of the PSA hydrogen extraction module, and the process gases including desorption gas, flushing gas, vacuum air, equalizing gas, forward venting gas, final charging gas, and system flushing gas from inside and outside their respective systems, all flow into and out of each adsorption tower / unit through the corresponding channels and pipes in their respective multi-channel rotary valves. This makes the PSA methane concentration and PSA hydrogen extraction modules in the energy feedstock module suitable for miniaturized skid-mounted installation.

[0021] The beneficial effects of this invention are:

[0022] (1) This invention fully utilizes biogas as a renewable resource and its relatively inexpensive feedstock for hydrogen production. While ensuring the energy supply of the BSMR hydrogen production module, it minimizes the consumption of biogas fuel gas. The surplus steam and energy generated by the hydrogen production module provide the necessary hot water and heat for the ALK hydrogen production module. Simultaneously, the BSMR hydrogen production module can utilize the byproduct pure oxygen (O2) from ALK hydrogen production, along with process gases or H2-containing desorbed gas from PSA hydrogen extraction, for combustion in the combustion chamber at the top of the converter / reactor within the BSMR hydrogen production module. The resulting heat of reaction powers the radiative converter / reactor of the BSMR hydrogen production module. The system provides sufficient energy for subsequent medium- and high-temperature conversion reactions, significantly reducing the consumption of feedstock fuel gas and flue gas emissions associated with traditional steam reforming (SMR) hydrogen production. Simultaneously, it provides surplus heat and hot water to the ALK hydrogen production module to achieve the required operating temperature. Furthermore, the H2-containing conversion gas produced by the SMR hydrogen production module has the same pressure as the crude H2 produced by the ALK hydrogen production module, eliminating the need for further compression and allowing it to directly enter the PSA hydrogen extraction module for H2 purification. This further reduces the overall energy consumption and emissions of the hydrogen production system while increasing the yield of H2 product gas. This significantly lowers the cost of hydrogen production from biogas feedstock and compensates for the shortcomings of the ALK process.

[0023] The high cost and low conversion rate of hydrogen production by water electrolysis are addressed, but the total yield of H2 product gas is greater than 85%.

[0024] (2) By coupling ALK water electrolysis hydrogen production with BSMR biogas hydrogen production in this invention, the two hydrogen production modes can be flexibly switched and adjusted according to the natural gas price and electricity price in the hydrogen-using market area, thereby further reducing operating costs. For example, when the electricity price is relatively low at night, the demineralized water flow rate entering the ALK hydrogen production module can be increased by controlling the demineralized water valve in the process, while the demineralized water steam flow rate of the biogas feed can be reduced to increase the proportion of water electrolysis hydrogen production. Conversely, the proportion of biogas hydrogen production can be increased during the power shortage season. In areas with high environmental requirements, the proportion of biogas hydrogen production can be reduced while the proportion of water electrolysis hydrogen production can be increased. In areas rich in biomass resources, biogas can be used to directly generate electricity to provide sufficient power for water electrolysis hydrogen production or to increase the proportion of biogas hydrogen production. In addition, this invention can also operate water electrolysis hydrogen production or biogas hydrogen production independently for a period of time to cope with the instability of biogas production or fluctuations in the electricity market.

[0025] (3) The present invention can be implemented in a miniaturized skid-mounted configuration, with a minimum size of 20–100 Nm. 3 / h, suitable for hydrogen production layout within hydrogen refueling stations and distributed hydrogen production.

[0026] (4) The present invention can take advantage of the different concentrations of the high-purity H2 produced by water electrolysis and the low-concentration H2 produced by the BSMR hydrogen production module, and feed them into different adsorption towers / devices in the PSA hydrogen extraction module to maximize the efficiency of PSA separation and purification of H2.

[0027] (5) This invention can utilize a variety of electrical energy sources, including clean energy such as hydropower, thermal power, photovoltaic power, wind power, and nuclear power, as well as natural gas power generation and biomass biogas and solid waste thermal power, which are low-carbon and waste resource recycling. In particular, biomass biogas can be used as raw material gas and fuel gas for BSMR hydrogen production modules, and can also be used to generate electricity to provide some electricity for water electrolysis hydrogen production, further improving the environmental friendliness of hydrogen production. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the process of Embodiment 1 of the present invention.

[0029] Figure 2 This is a schematic diagram of the process of Embodiment 4 of the present invention. Detailed Implementation

[0030] To enable those skilled in the art to better understand the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings.

[0031] Example 1

[0032] like Figure 1As shown, a hybrid hydrogen production system coupling biogas hydrogen production and alkaline water electrolysis hydrogen production consists of an energy feedstock module, an alkaline water electrolysis (ALK) hydrogen production module, a biogas (BSMR) hydrogen production module, a pressure swing adsorption (PSA) hydrogen extraction module, and pipelines, valves, heaters, coolers, and heat exchangers connecting the modules. The specific process of each module in the hybrid hydrogen production system is as follows:

[0033] (1) Energy feedstock module: Biogas from biomass anaerobic fermentation flows out of the gas holder or gas bag. Its typical components are methane (CH4) 65% (v / v), carbon dioxide (CO2) 30-34%, and other impurities 1-3%, with a flow rate of 1000 Nm³. 3 / h, of which the sulfur content is approximately 800ppm, is pressurized to 30kPa by a Roots blower.

[0034] (Table) After entering the lower part of the wet desulfurization tower, the desulfurization solution comes into contact with the desulfurization lean solution flowing from top to bottom on the surface of the packing. It absorbs various reducing and acidic gases. Air is then drawn in by injection, and the solution is regenerated after oxidation, producing sulfur foam. The clear desulfurization solution after foam separation can be recycled. The sulfur foam is further processed in a sulfur melting kettle to produce sulfur. The hydrogen sulfide (H2S) content in the biogas after crude desulfurization is less than 300 ppm. The biogas after crude desulfurization is further desulfurized using two dry iron oxide adsorption desulfurization towers. One tower is in adsorption mode, while the other is in standby mode. The crude desulfurized biogas enters from the lower part of the adsorption tower, passing through the iron oxide packing layer inside, where the H2S is adsorbed or absorbed and reacted into sulfides or... Polysulfides remain in the packing layer. After pre-purification, the biogas is discharged from the top of the desulfurization tower, with an H2S content of less than or equal to 25 ppmv. The pre-purified biogas is pressurized to 0.6 MPa by a compressor and then enters a gas-liquid separator to remove free water and oil. It then enters a PSA methane concentration system consisting of 6 adsorption towers, which uses vacuum desorption. The adsorption towers are filled with a composite adsorbent including activated carbon, mainly carbon molecular sieves, and alumina. The CO2 content of the methane concentrate flowing out is ≤3% (v / v). 85% of this is used as feed gas for the subsequent BSMR hydrogen production module. After being pressurized to 1.8–2.0 MPa and preheated to 240–320°C by a compressor, it enters the hydrorefining desulfurization. A portion of this gas comes from the ALK hydrogen production module with a purity of 99%.0% H2, after gas-liquid separation and / or catalytic deoxygenation, is used as the hydrogen source. The purified biogas feedstock, after hydrodesulfurization using zinc oxide as a catalyst, is mixed with medium- and low-pressure steam from the BSMR hydrogen production module to form a mixed steam of purified methane concentrate and water vapor. This mixed steam enters the BSMR hydrogen production module. 15% of the methane concentrate, along with O2 from the ALK hydrogen production module, serves as combustion gas, and desorbed gas from the PSA hydrogen extraction module serves as fuel gas and supplementary fuel gas. This mixture enters the combustion chamber at the top of the radiant and convection tubular converter in the BSMR hydrogen production module for combustion. The resulting heat provides heat for the convection section of the converter, preheating converter, demineralized water steam, steam drum, waste heat boiler, and medium- and high-temperature shift reaction in the BSMR hydrogen production module. Water from municipal tap water or industrial water, after demineralization and preheating of the demineralized water, is used for further processing. After reaching 70-90℃, 20-40% of the process water, used as raw material, enters the storage tank of the ALK hydrogen production module for water electrolysis to produce hydrogen. 60-80% enters the deaerator of the BSMR hydrogen production module and, through the hot water pump and steam boiler, generates demineralized water steam and the convection section of the reformer to form process steam. This process steam from the energy feedstock module mixes with purified methane concentrate to form mixed steam, which then enters the BSMR hydrogen production module. High-temperature flue gas from the reformer combustion chamber of the BSMR hydrogen production module undergoes heat exchange and gas-liquid separation with the streams from both the BSMR and ALK hydrogen production modules. The water is returned to the pretreatment system for recycling, while the gas is discharged as waste gas. Electricity from the biogas generator is directly connected to the control system and electric heater of the ALK hydrogen production module, providing the startup and backup power required for water electrolysis.

[0035] (2) The ALK hydrogen production module receives industrial AC power from the energy feedstock module and connects to the control system consisting of a transformer and control cabinet. Simultaneously, process water and alkali solution from the water tank and alkali tank flow into the electrolyzer via an alkali solution separator and alkali solution circulation pump. The electrolyzer is a single-cell unit with a concentration of [missing information].

[0036] A 25–30% NaOH solution was used as the electrolyte; the operating temperature of the electrolytic cell was 70–90℃; and the current density of the water electrolytic cell was 0.2–0.4 A / cm³. 3 The electrolyzer voltage (cell voltage) is less than 0.2V for hydrogen evolution and greater than 0.6V for oxygen evolution. The anode material is primarily nickel and its alloys, as well as nickel-based composite materials. The cathode material is primarily precious metals such as Pd / Pt. The electrolytic membrane material is primarily asbestos. O2 with a concentration of approximately 98.5% and a pressure of approximately 1.7MPa is evolved from the anode and enters the oxygen storage tank, then is output as fuel gas to the BSMR hydrogen production module. O2 with a concentration of 99.2-99.5%, a pressure of 1.6-1.8MPa, and a flow rate of 200-300Nm³ is evolved from the cathode. 3After water is removed by the water-gas separator, the H2 produced per hour does not require further catalytic deoxygenation. 90-95% of it is directly fed into the PSA hydrogen extraction module for the preparation of H2 product gas, while 5-10% is used as the H2 source for the hydrogenation and desulfurization of methane concentrate gas in the original energy feedstock module.

[0037] (3) In the BSMR hydrogen production module, the purified methane concentrate from the energy feedstock module is mixed with medium- and low-pressure process steam to form a mixed steam. This mixed steam is preheated by a convection preheater and then enters the reforming and conversion (SMR) tubular reformer / reactor of the BSMR hydrogen production module for reforming and conversion. The fuel gas enters the combustion chamber at the top of the tubular reformer for combustion, and the catalytic bed filled with nickel / nickel-based catalyst inside the reformer tubes undergoes radiative and convective heat transfer. The mixed steam flows through the catalytic bed inside the tubes for conversion. The reaction temperature is 800–870℃, and the reaction pressure is…

[0038] The converted gas generated in the conversion reaction, at a pressure of 1.8–2.0 MPa, enters a medium-temperature shift reactor using iron oxide / zinc and iron / zinc-based catalysts after heat exchange in the conversion waste boiler. The reaction temperature is 360–430 °C, and the reaction pressure is 1.6–1.8 MPa. After the medium-high temperature shift reaction, the converted gas forms shift gas, which consists of 75–80% H2, 19–24% carbon dioxide (CO2), less than or equal to 1% carbon monoxide (CO), unreacted methane (CH4), and trace amounts of other hydrocarbon impurities. The shift gas then exchanges heat with boiler feedwater and a demineralized water preheater. The hydrogen is extracted into the PSA hydrogen extraction module. The heat required for the conversion reaction in the tubes of the converter is obtained by using the crude purified biogas or purified methane concentrate gas (excluding feed gas) from the energy feed module as fuel gas, which, together with O2 from the ALK hydrogen production module and desorbed gas from the PSA hydrogen extraction module, enters the BSMR hydrogen production module for combustion reaction. The high-temperature flue gas obtained from the combustion reaction in the combustion chamber at the top of the converter flows outside the tubes and is obtained through radiative heat transfer. The high-temperature flue gas is used as the heat source for the preheater, process steam and the waste heat source for the conversion boiler, and is discharged as flue gas after heat exchange cooling and treatment.

[0039] (4) In the PSA hydrogen extraction module, H2 with a purity of 99.2-99.5% and a pressure of 1.6-1.8 MPa from the ALK hydrogen production module is dehydrated by a water-gas separator without further catalytic deoxygenation. The H2, after being directly cooled by heat exchange, is either separately or mixed with shift gas from the BSMR hydrogen production module containing 75-80% H2 concentration and enters a composite adsorbent bed consisting of four series-connected adsorbent towers loaded with alumina, silica gel, activated carbon, and molecular sieves. The adsorption towers are connected by pipes, programmable control valves, and regulating valve groups to form a pressure swing adsorption (PSA) system. The system operates at an adsorption pressure of 1.6–1.8 MPa and an adsorption temperature of 20–50 °C. Four adsorption towers alternately perform adsorption and desorption cycles, including adsorption, forward discharge, pressure equalization, reverse discharge, vacuum rinsing, pressure equalization and final charging. The rinsing gas is product gas, while the final charging gas is H2 from the ALK hydrogen production module, which has undergone catalytic deoxygenation and pressurization, yielding H2 product gas with a purity greater than 99.99%. The pressure is 1.6–1.8 MPa, the temperature is 20–50 °C, and the flow rate is 1200–1500 Nm³. 3 / h, enters the H2 product gas tank, and the desorbed gas obtained from it enters the buffer tank and is returned to the BSMR hydrogen production module for recycling as supplementary fuel gas. Thus, the total yield of H2 product gas is greater than or equal to 85%.

[0040] Example 2

[0041] like Figure 1 As shown, based on Example 1, the biogas from the energy feedstock module, sourced at room temperature and 0.3 MPa, has a flow rate of 1,000 Nm³. 3 / h adjusted to 500 Nm 3 The process involves a flow rate of 85% feed gas and 15% fuel gas from the BSMR hydrogen production module. O2 from the ALK hydrogen production module and desorbed gas from the PSA hydrogen extraction module are used as fuel and supplementary fuel gas. The corresponding demineralized water steam volume is adjusted to only 60-70% of the original. The ratio of demineralized water / demineralized water steam entering the ALK hydrogen production module to that entering the SMR hydrogen production module is 4-5:5-6, effectively increasing the water-to-carbon ratio in the BSMR hydrogen production module's converter. The conversion reaction temperature is 780-840℃, and the medium-temperature shift reaction temperature is 350-430℃. The electrolyzer in the ALK hydrogen production module operates at 70-90℃, maintaining the same hydrogen evolution rate. After gas-liquid separation, the hydrogen is mixed with the shift gas from the BSMR hydrogen production module and enters the PSA hydrogen extraction module for hydrogen extraction. Therefore, the flow rate of H2 product gas with a purity greater than 99.99% produced from the PSA hydrogen extraction module is 900-1200 Nm³. 3 / h, of which, the H2 product gas produced by the ALK hydrogen production module accounts for 35-45%, which is nearly 30-40% higher than that in Example 1, realizing the ratio adjustment of alkaline water electrolysis hydrogen production and biogas hydrogen production in the hybrid hydrogen production system.

[0042] Example 3

[0043] Based on Example 1, the pipeline connections between the biogas feedstock and fuel gas in the energy feedstock module and the BSMR hydrogen production and PSA hydrogen extraction modules are switched / disconnected. The biogas power generation, demineralized water preheater, and steam electric heater (using electric heating) are maintained for preheating and heating. The pipeline connections between the energy feedstock module and the ALK hydrogen production module, and between the ALK hydrogen production module and the PSA hydrogen extraction module, are opened separately. The inexpensive electricity from the energy feedstock module is input into the ALK hydrogen production module, the PSA hydrogen extraction module, and the electrically heated demineralized water preheater for ALK water electrolysis to produce hydrogen. The resulting hydrogen has a purity of 99.2–99.5%, a pressure of 1.6–1.8 MPa, and a flow rate of 250–350 Nm³. 3 After water removal and catalytic deoxygenation in the water-gas separator, the H2 produced per hour all enters the PSA hydrogen extraction module for H2 product gas production. This eliminates the need for hydrogenation and desulfurization of the feedstock gas returned to the energy feedstock module and pressurization of the H2 flowing out of the ALK hydrogen production module. At this point, the five adsorption towers in the PSA hydrogen extraction module sequentially undergo a cyclical operation of adsorption, two pressure equalization drops, reverse release, vacuuming, vacuum rinsing, two pressure equalization rises, and final charging. The adsorption pressure is 1.6–1.8 MPa, the adsorption temperature is 20–40 °C, the rinsing gas is the product gas, and the final charging gas is H2 from the ALK hydrogen production module that has undergone water-gas separation and catalytic deoxygenation. As a result, the purity of the H2 product gas produced from the PSA hydrogen extraction module is greater than or equal to 99.999%, and the yield is greater than or equal to 80%.

[0044] Example 4

[0045] like Figure 2 As shown, based on Examples 1 and 2, the biogas flow rate is 500 Nm³. 3 / h, purified biogas after coarse purification and pre-purification desulfurization is transported by a blower to a PSA methane concentration system, which is composed of five adsorption towers with five 5-channel rotary valves placed in the center of each tower. These towers contain composite adsorbent beds composed of carbon molecular sieves, alumina, silica gel, and a small amount of activated carbon. The five-channel rotary valves rotate counterclockwise at a speed of ω = 200-400 s. The PSA methane concentration system is formed by the material pipelines connecting the inlet and outlet of the rotary valves to the pre-purified biogas, concentrated methane gas, desorbed gas, and flushing gas, as well as the process pipelines connecting the top and bottom of the five adsorption towers and the rotary valves, and the buffer tanks for concentrated methane gas / desorbed gas / or flushing gas. Each adsorption tower undergoes adsorption (A), reverse release (D), vacuuming (V), vacuum flushing (VP), and final charging (FR) steps as the five-channel rotary valves rotate counterclockwise, before entering the next adsorption tower. The adsorption and desorption process is a closed-loop operation. Simultaneously, the material gas and process gas entering and exiting the other four adsorption towers also undergo corresponding adsorption and desorption closed-loop operation steps within one adsorption tower through continuous rotation of a rotary valve switching between the material gas channel and the process gas channel. The adsorption pressure is 0.3 MPa, and the adsorption temperature is 20–50 °C. Thus, concentrated methane gas with a methane content greater than 96% and a CO2 content less than 3% is obtained from the PSA methane concentration system. Simultaneously, the nickel-based catalyst in the conversion furnace tubes of the BSMR hydrogen production module is replaced with a low-temperature conversion catalyst containing Ni-Co metal active components supported on carbon nanotubes. The concentrated methane gas is then directly sent to the hydrodesulfurization step by a blower without pressurization for further desulfurization before being preheated and mixed with demineralized water vapor before entering the BSMR hydrogen production module for reaction. The conversion reaction temperature is 500–600 °C, and the conversion reaction pressure is 0.The heat required for the conversion reaction at 3MPa is provided by the combustion of O2 / high-temperature flue gas from the ALK hydrogen production module and the desorbed gas from the PSA hydrogen extraction module at the bottom of the conversion tubes inside the converter. This eliminates the need to consume concentrated biogas (purified gas) as fuel gas. Mixed steam flows downwards inside the conversion tubes, while high-temperature flue gas flows upwards outside, resulting in convective heat transfer between the inside and outside of the tubes. This provides the heat required for the reaction temperature within the tubes, thus eliminating the need for the high-temperature radiation section in Examples 1 or 2. This allows for a more efficient conversion process, including the converter, its piping, and corresponding modules. The volume is reduced by nearly 1 / 3 to 1 / 2. Simultaneously, a 7-channel rotary valve replaces the programmable valve group and regulating valve group of the PSA hydrogen extraction module composed of 5 adsorption towers in Example 1 or 2. The 7-channel rotary valve is placed in the center of the 5 adsorption towers. Each adsorption tower contains 5 axially flowing fixed beds with a height-to-diameter ratio of 4 to 6, containing a composite adsorbent composed of activated alumina, silica gel, activated carbon, and molecular sieves. The 7-channel rotary valve rotates counterclockwise at a speed of ω = 400–800 s. The inlet and outlet of the rotary valve are connected to the outside of the PSA hydrogen extraction module by H2 and S from the SOEC hydrogen production module. A PSA hydrogen extraction module is formed by the conversion gas (which serves as the feed gas (F)) of the MR hydrogen production module, the material pipelines for the material gas consisting of desorbed gas and flushing gas, the process pipelines connecting the upper and lower parts of the adsorption tower and the rotary valve, and the buffer tanks for H2 product gas / desorbed gas / or flushing gas. In this module, an adsorption tower (1) undergoes the following steps as the 7-channel rotary valve rotates counterclockwise: adsorption (A), pressure equalization (ED), reverse release (D), vacuuming (V), vacuum flushing (VP), pressure equalization rise (ED), and final charging (FR). The process then proceeds to the next closed-loop adsorption and desorption cycle. Meanwhile, the material and process gases entering and exiting adsorption towers 2, 3, 4, and 5 undergo corresponding adsorption and desorption cycles in adsorption tower 1, with the rotary valve continuously switching between the material gas and process gas channels. This process allows for the production of high-purity hydrogen (H2) product gas with a purity greater than or equal to 99.99% from the PSA hydrogen extraction module, with a yield greater than or equal to 88%, and an H2 product gas flow rate increased to 1000 Nm. 3Achieving a rate of over [per hour], this system realizes both high purity and high yield in a simulated rotating PSA process based on an axial flow fixed adsorption bed. To make the entire hybrid hydrogen production unit more suitable for miniaturization, the 5-channel rotary valve of the PSA methane concentration system in the energy feedstock module is placed above the 7-channel rotary valve of the PSA hydrogen extraction module. Simultaneously, the 5 adsorption towers of the PSA methane concentration system and the 5 adsorption towers of the PSA hydrogen extraction module are alternately distributed around the upper and lower rotary valves, forming a ring, and share a single vacuum pump and desorption gas pipeline. The entire hybrid hydrogen production unit is reduced by nearly 2 / 3 compared to Example 2, making it suitable for hydrogen production unit layouts requiring on-site hydrogen refueling.

[0046] Obviously, the embodiments described above are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments described in this invention, all other embodiments obtained by those skilled in the art without creative effort, or structural changes made under the guidance of this invention, that have the same or similar technical solutions as this invention, all fall within the protection scope of this invention.

Claims

1. A hybrid hydrogen production system coupling biogas hydrogen production and alkaline water electrolysis hydrogen production, characterized in that, The hybrid hydrogen production system consists of an energy feedstock module, an alkaline water electrolysis (ALK) hydrogen production module, a biogas conversion (BSMR) hydrogen production module, a pressure swing adsorption (PSA) hydrogen extraction module, and pipelines, valves, and heat exchangers connecting these modules. The energy feedstock module is responsible for pretreatment of biogas feedstock, including methane concentration, biogas power generation, and the treatment of process water, boiler water, and process steam. It optimizes the composition and energy of each feedstock to meet the requirements of downstream modules, including BSMR hydrogen production modules using concentrated methane as feedstock and biogas or concentrated methane as fuel gas. The system includes a PSA hydrogen production module that uses the generated H2-containing desorbed gas as supplementary fuel gas; an ALK hydrogen production module that generates pure oxygen gas; a hydrogenated gas and demineralized water storage tank module; a room temperature or heater or heat exchanger module; an atmospheric pressure or booster compressor module; a methane concentrate desulfurization and process steam and mixed steam treatment module; a biogas generator or hydropower or other power supply module; a process water and boiler water demineralization pretreatment and heat exchange module; and process raw materials, pure oxygen fuel, power grid inlet and outlet pipelines and control valves inside and outside the modules. The ALK hydrogen production module mainly consists of one or more stages connected in series. The module consists of parallel alkaline water electrolyzers, gas-liquid processors, rectifiers, electric heaters, control systems, water pumps, alkali tanks, water tanks, and power, hydrogen (H2), and oxygen (O2) gas pipelines and process (hot / cold) water pipelines and control valves connecting the module internally and externally. The BSMR hydrogen production module mainly includes a preheating converter for mixed steam formed by mixing desulfurized methane concentrate with water vapor, an SMR converter / reactor with a combustion chamber at the top and convection and radiation sections at the bottom, a medium-high temperature shift reactor, a gas-liquid separator, a heat exchanger, a steam drum, and a waste heat boiler. The module includes pipelines connecting mixed steam, pre-converted gas, converted gas, shift gas, fuel gas, PSA hydrogen extraction and desorption gas, demineralized water, boiler feedwater, steam storage tank, circulating water pipeline, deaerator, conveying and circulating pumps, and control valves. The PSA hydrogen extraction module consists of multiple series / parallel adsorption towers, a desorption gas buffer tank, and pipelines connecting power, H2 product gas / desorption gas, H2 from the ALK hydrogen production module, and shift gas from the BSMR hydrogen production module, as well as programmable control valves and regulating valve groups. The specific process is as follows: (1) Energy raw material module: Biogas from anaerobic fermentation is used as raw material gas and is fed into the dry or wet coarse desulfurization pre-purification process by a blower. After coarse purification, the biogas is pressurized to 0.6~1.0MPa by a compressor and enters the PSA methane concentration system, which consists of multiple series / parallel adsorption towers loaded with fixed adsorbent beds mainly composed of carbon molecular sieves. The desorbed gas generated by vacuum desorption is directly discharged. The methane concentrated gas generated from it has a methane content of greater than or equal to 92%. After being pressurized to 1.0~4.0MPa and preheated to 250~380℃, it enters the hydrorefining desulfurization process, which is derived from the ALK hydrogen production module. H2 is used as the hydrogen source. The purified methane concentrate after desulfurization is mixed with medium- and low-pressure steam from the BSMR hydrogen production module to form a natural gas-water vapor mixture, which enters the BSMR hydrogen production module. Raw purified biogas or purified methane concentrate from within the module, O2 from the ALK hydrogen production module or air from outside the boundary, and desorbed gas from the PSA hydrogen extraction module are used as fuel gas or supplementary fuel gas and enter the combustion chamber of the converter in the BSMR hydrogen production module for combustion, providing heat for the catalytic conversion reaction in the BSMR converter / reactor. Simultaneously, municipal tap water... Alternatively, industrial water is used. A portion is desalinated and preheated to 70-90°C. Another portion of the desalinated water is used as feedstock in the ALK hydrogen production module's water tank, while the remaining portion is used as process water in the BSMR hydrogen production module's deaerator. This process water is then processed by a hot water pump, a steam boiler to generate desalinated steam, and the converter's convection section to form process steam. This process steam from the energy feedstock module mixes with purified methane concentrate to form mixed steam, which then enters the BSMR hydrogen production module. A portion of the desalinated water, without preheating, is used as cooling water to cool the BSMR hydrogen production module. The cooled water is then returned as process circulating water. The exhaust gas from the BSMR hydrogen production module and the ALK hydrogen production module undergoes heat exchange and gas-liquid separation. The water is returned for pretreatment, and the gas is emitted. Electricity from biogas power generation, urban power grid, or industrial power grid is directly connected to the control system of the ALK hydrogen production module to provide the power required for water electrolysis hydrogen production and the start-up or independent operation of the electric heater. Alternatively, on-site power generation equipment or peak-shaving power, including direct biogas power generation, pipeline natural gas power generation, hydropower station, and cogeneration, can be used to provide power to the ALK hydrogen production module. Among these, direct biogas power generation provides sufficient power for the miniaturized skid-mounted hydrogen production equipment of the on-site hydrogen refueling station. (2) ALK hydrogen production module: When the power input from the energy feedstock module is connected to the control system consisting of transformer and control cabinet, the process water from the water tank / alkali tank, the process water formed by the alkali separator and the process water from the alkali circulation pump flow into the electrolyzer. The operating temperature of the electrolyzer is 70~90℃. O2 with a concentration of 98.5~99.2% and a pressure of 1.0~2.0MPa is released from the anode of the electrolyzer and enters the oxygen storage tank. It is output as fuel gas into the BSMR hydrogen production module. H2 with a concentration of 99.0~99.8% and a pressure of 1.0~2.0MPa is released from the cathode of the electrolyzer. After water is removed by the water-gas separator, part of it directly enters the PSA hydrogen extraction module to prepare H2 product gas, and part of it is used as the H2 source for the hydrogenation and desulfurization of methane concentrate in the energy feedstock module. (3) In the BSMR hydrogen production module, the purified methane concentrate gas from the energy feedstock module is mixed with steam and preheated by a convection preheater before entering the reforming conversion (SMR) tubular reformer / reactor of the BSMR hydrogen production module for reforming conversion reaction. The reformer or reactor tubes are filled with nickel / nickel-based catalysts. The mixed steam flows through the catalyst bed in the tubes for conversion reaction. The reaction temperature is 700~950℃ and the reaction pressure is 1.0~4.0MPa. The converted gas generated by the conversion reaction is then heat-exchanged in the conversion waste heat boiler and enters the medium-high temperature shift reactor. The reaction temperature is 300~500℃ and the reaction pressure is 1.0~4.0MPa. After the conversion gas undergoes the medium-high temperature shift reaction, it forms shift gas with the composition of 70~85% H2 and 13~28% carbon dioxide (CO2). The converted gas contains less than 1% carbon monoxide (CO), unreacted methane (CH4), and other trace hydrocarbon impurities. After heat exchange with boiler feedwater and demineralized water, the converted gas enters the PSA hydrogen extraction module for hydrogen extraction. The heat required for the reaction in the converter / reactor is obtained by using crude purified biogas or purified methane concentrate gas from the energy feedstock module (excluding feed gas) as fuel gas, mixed with O2 from the ALK hydrogen production module and desorbed gas from the PSA hydrogen extraction module, or air from outside the system, and then entering the BSMR hydrogen production module for combustion reaction. The high-temperature flue gas obtained from the combustion reaction in the burners at the top, bottom, or sides of the converter flows through the tubes and is obtained through radiative heat transfer. The high-temperature flue gas is used as the heat source for the preheater, process steam, and waste heat boiler, and is discharged as flue gas after heat exchange, cooling, and treatment. (4) PSA hydrogen extraction module: H2 with a purity of 99.0~99.8% from ALK hydrogen production module and catalytically deoxygenated, and shift gas with an H2 concentration of 70~85% from BSMR hydrogen production module are respectively or mixed and enter a pressure swing adsorption (PSA) system consisting of at least 3 or more composite bed adsorption towers / devices connected in series, parallel or series-parallel, pipelines between adsorption towers / devices, program control valves and regulating valve groups. The adsorption pressure is 0.8~3.8MPa and the adsorption temperature is 20~80℃. The adsorption towers / devices alternately switch to perform adsorption and desorption cycle operations including adsorption, pressure equalization, forward release, reverse release, vacuum / rinsing and final charging steps. H2 product gas with a purity of greater than or equal to 99.99% is obtained and enters the H2 product gas tank. The desorbed gas obtained enters the buffer tank and is returned to the BSMR hydrogen production module for recycling as supplementary fuel gas. Thus, the total yield of H2 product gas is greater than or equal to 85%.

2. The hybrid hydrogen production system coupling biogas hydrogen production and alkaline water electrolysis hydrogen production as described in claim 1, characterized in that, The ratio of H2 with a purity of 99.0~99.8% and catalytically deoxygenated produced by the ALK hydrogen production module to the shift gas with an H2 concentration of 70~85% produced by the BSMR hydrogen production module is 4~8:2~6. This ratio is obtained by adjusting the usage of demineralized water / process steam, feedstock and fuel biogas / O2 in the ALK hydrogen production module / desorption gas / make-up air in the PSA hydrogen extraction module.

3. The hybrid hydrogen production system coupling biogas hydrogen production and alkaline water electrolysis hydrogen production as described in claim 1, characterized in that, The ALK hydrogen production module and the BSMR hydrogen production module operate independently by switching on and off the connections between the demineralized water / process steam, feedstock / fuel biogas and the desorption gas pipeline and logistics pipeline of the O2 / PSA hydrogen extraction module of the ALK hydrogen production module. The H2 product gas output of the PSA hydrogen extraction module depends on the maximum capacity of the ALK hydrogen production module and the BSMR hydrogen production module to produce H2 with a purity of 99.0~99.8% and shift gas with an H2 concentration of 70~85%, respectively.

4. The hybrid hydrogen production system coupling biogas hydrogen production and alkaline water electrolysis hydrogen production as described in claim 1, characterized in that, The hybrid hydrogen production system has an H2 product gas production capacity of 100~20,000 Nm3 / h, wherein the ALK hydrogen production module has a hydrogen production capacity of 20~12,000 Nm3 / h and an operating flexibility of 70~100%, the BSMR hydrogen production module has a hydrogen production capacity of 80~16,000 Nm3 / h and an operating flexibility of 40~100%, and the PSA hydrogen extraction module has a hydrogen production capacity of 20~20,000 Nm3 / h and an operating flexibility of 30~110%.

5. The hybrid hydrogen production system coupling biogas hydrogen production and alkaline water electrolysis hydrogen production as described in claim 1, characterized in that, The BSMR hydrogen production module's converter / reactor is filled with a low-temperature conversion catalyst. The conversion reaction temperature is 400~600℃, and the conversion reaction pressure is adjusted to 0.2~0.8MPa. The biogas feedstock gas in the energy feedstock module is conveyed under pressure by a blower without the need for pressurization. At the same time, biogas is not used as fuel gas. Instead, desorbed gas from the PSA hydrogen extraction module and O2 from the ALK hydrogen production module are used as combustion gas. The H2 product gas yield is greater than 88%. It is suitable for miniaturized skid-mounted hybrid hydrogen production systems with a hydrogen production scale of 100~1,000 Nm3 / h.

6. The hybrid hydrogen production system coupling biogas hydrogen production and alkaline water electrolysis hydrogen production as described in claim 1, characterized in that, The BSMR hydrogen production module's converter / reactor is filled with a bifunctional conversion and shift catalyst. As a result, the CO content in the converted gas flowing out of the BSMR hydrogen production module's converter / reactor is less than 3-5%, and it can directly enter the PSA hydrogen extraction module without undergoing a medium-to-high temperature shift reaction. In this case, the composite adsorbent packed in the PSA adsorption tower / reactor must have an increased amount of proprietary CO molecular sieve.

7. The hybrid hydrogen production system coupling biogas hydrogen production and alkaline water electrolysis hydrogen production as described in claim 1, characterized in that, The ALK hydrogen production module generates H2 with a purity of 99.0~99.8% after catalytic deoxygenation, which is then mixed with the shift gas with an H2 concentration of 70~85% generated by the BSMR hydrogen production module. The mixture is then fed into one or more identical adsorption towers / recorders in the PSA hydrogen extraction module. Alternatively, when the adsorption towers / recorders in the PSA hydrogen extraction module employ two-stage adsorption, the shift gas from the BSMR hydrogen production module first enters a first-stage PSA decarbonization (CO2) consisting of at least three adsorption towers / recorders. The decarbonized shift gas flowing out from this stage is then mixed with H2 with a purity of 99.0~99.8% after catalytic deoxygenation generated by the ALK hydrogen production module and enters a second-stage PSA purification consisting of at least four adsorption towers / recorders to obtain H2 product gas. The first-stage desorbed gas flowing out from the first-stage PSA decarbonization stage is directly emitted as flue gas, while the second-stage desorbed gas flowing out from the second-stage PSA purification stage is returned to the BSMR hydrogen production module as supplementary fuel gas for recycling.

8. The hybrid hydrogen production system coupling biogas hydrogen production and alkaline water electrolysis hydrogen production as described in claim 1, characterized in that, In the energy feedstock module, the program control valves and regulating valve groups connected to each adsorption tower / recorder in the PSA methane concentration system and PSA hydrogen extraction module are each replaced by a multi-channel rotary valve. The inlet and outlet of each adsorption tower / recorder in the PSA methane concentration and PSA hydrogen extraction systems are connected to the inlet and outlet of the upper and lower plates of the multi-channel rotary valve. Gases entering and exiting the PSA methane concentration system and PSA hydrogen production module include purified biogas, purified methane concentrate gas / H2 with a purity of 99.0~99.8% and catalytically deoxygenated from the ALK hydrogen production module, shift gas with an H2 concentration of 70~85% from the BSMR hydrogen production module, H2 product gas exiting the PSA hydrogen extraction module, and process gases including desorption gas, flushing gas, vacuum gas, equalizing gas, forward venting gas, final charging gas, and system flushing gas from within and outside the respective systems. All these gases flow through the corresponding channels and pipes in their respective multi-channel rotary valves to enter and exit each adsorption tower / recorder, making the PSA methane concentration and PSA hydrogen extraction modules in the energy feedstock module suitable for miniaturized skid-mounted installation.

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