Methanol reforming hydrogen production system and control method thereof

Abstract

The invention relates to the technical field of hydrogen energy, in particular to a methanol reforming hydrogen production system and a control method thereof.The system comprises a methanol-water mixing module, a fused salt phase change energy storage module, a reforming reaction module and a post-treatment module which are sequentially communicated; the fused salt phase change energy storage module comprises a phase change energy storage fused salt reactor as well as a heat release device I and a heat release device II which are arranged in the fused salt reactor, the output end of the methanol-water mixing module is connected with the heat release device I, and the output end of the heat release device I is connected with the reforming reaction module; the reforming reaction module comprises a reforming reactor with a built-in axial heating tube bundle, a catalytic reaction cavity is formed between tubes of the axial heating tube bundle, an in-tube channel of the axial heating tube bundle and the second heat release device form a circulation loop, and a heat transfer working medium is arranged in the circulation loop. By combining phase change energy storage and an efficient heating working medium circulation loop, the problem that the temperature of a catalyst is not constant in a traditional hydrogen production process is solved, and the reaction efficiency, the hydrogen yield and the hydrogen purity of the system are fundamentally improved.

Description

Technical Field

[0001] The present invention relates to the field of hydrogen energy technology, and in particular to a methanol reforming hydrogen production system and a control method thereof. Background Art

[0002] Hydrogen energy is an important secondary energy source. Hydrogen energy can be used as a carrier to absorb renewable energy such as photovoltaic and wind power. It has the characteristics of high energy density and no pollution during combustion. However, as an energy source, hydrogen also has obvious weaknesses, namely, low volume density and inconvenient storage and transportation.

[0003] Currently, the main methods of hydrogen storage are: high-pressure gas storage, low-temperature liquid storage, solid hydrogen storage material storage, liquid organic chemical storage, etc.

[0004] If it is stored in a gaseous state at room temperature, hydrogen must be pressurized to a high pressure state for easy transportation. However, under high pressure, the weight of the storage and transportation container accounts for a very large proportion, so the economic distance of transportation is limited and it is not suitable for long-distance transportation. If long-distance transportation is required, hydrogen needs to be cryogenically liquefied into liquid, that is, made into cryogenic liquid hydrogen, but making hydrogen into cryogenic liquid hydrogen consumes a lot of energy, which will affect the economy. Solid hydrogen storage material storage and liquid organic chemical storage have not yet reached the conditions for engineering application.

[0005] Due to the above reasons, people have found a suitable carrier of hydrogen energy, namely methanol.

[0006] The standard boiling point of methanol is 64.7℃. It is liquid at room temperature and is very convenient to store and transport. Methanol can be directly synthesized from hydrogen and carbon dioxide. For areas with abundant photovoltaic and wind power, water electrolysis is used to produce hydrogen to convert new energy electricity that cannot be absorbed by the power grid into hydrogen, and then synthesize methanol. Methanol can be used directly as a clean fuel, and can also be reduced to hydrogen and used as hydrogen energy.

[0007] It can be seen from this that when methanol is used as a carrier of hydrogen energy, it only needs to be synthesized into methanol from hydrogen at the hydrogen production site, then transported to the site of use using conventional liquid tanker transportation methods, and then reduced to hydrogen through a chemical reaction before it can be used.

[0008] There are several reaction methods to reduce methanol to hydrogen. Among them, the methanol-water mixed steam catalytic reforming reaction is suitable for use in hydrogen fuel cells and other hydrogen-using equipment because the reaction conditions are relatively mild, the catalyst used is relatively cheap, and the product after the reaction has a high hydrogen content and a very low by-product carbon monoxide content.

[0009] The reforming reaction of methanol-water mixed steam is a strongly endothermic reaction, which requires heat from the outside. In addition, it requires both the heat required to heat the room temperature methanol-water mixture to vaporize it into methanol-water mixed steam and the heat required for the reforming reaction of the methanol-water mixed steam.

[0010] In the existing methanol-water reforming hydrogen production method, the heat required for the reforming reaction comes from the heat generated by the combustion of methanol, that is, a part of the raw methanol is used as fuel to burn with air to generate heat, part of the heat is used to heat the methanol-water mixture in the vaporization chamber to vaporize it, and the other part of the heat is used to heat the catalyst in the reaction zone so that the methanol-water mixed steam absorbs heat in the catalyst to cause the reforming reaction.

[0011] It can be seen that in order to obtain hydrogen through the reforming reaction of methanol, the above method needs to consume a certain amount of hydrogen production raw material (methanol), and the methanol reforming hydrogen production reaction is a strong endothermic reaction. In order to meet the heat required for the reaction, the amount of methanol required as fuel accounts for a large proportion, which greatly reduces the total hydrogen production of methanol. Therefore, this method is only suitable for small-scale methanol reforming hydrogen production, or for mobile occasions such as vehicles and ships.

[0012] When it is necessary to use methanol reforming to produce hydrogen on a large scale in a fixed place, if the above method is used, a considerable part of methanol will be consumed as fuel to burn and generate heat. This method not only reduces the hydrogen production of raw methanol, affecting economic benefits, but also from the perspective of energy conversion efficiency, using methanol as a hydrogen energy carrier as fuel to burn and generate heat at a lower temperature is also an inefficient way of utilization. Because to produce methanol, firstly, water must be electrolyzed by wind and solar green electricity to produce hydrogen, then hydrogen and carbon dioxide are combined to synthesize methanol, and then the methanol is transported to the place of use. After multiple energy conversions and transportation, the overall conversion efficiency is already relatively low. The reason why methanol is used as a hydrogen energy carrier is just to solve the problem of hydrogen transportation.

[0013] In order to adopt methanol reforming to produce hydrogen on a large scale in fixed locations, it is necessary to solve the problem of the heat required to heat and gasify the methanol-water mixture into methanol-water mixed steam, as well as the source of heat required for the reforming reaction of the methanol-water mixed steam. The source of this heat should be economical and efficient, rather than generated by burning raw methanol.

[0014] The information disclosed in this background technology section is only intended to deepen the understanding of the overall background technology of the present invention, and should not be regarded as acknowledging or suggesting in any form that the information constitutes the prior art known to those skilled in the art. Summary of the invention

[0015] The first purpose of the present invention is to provide a methanol reforming hydrogen production system, which does not use the method of burning raw methanol to generate heat, heat the methanol-water mixed liquid to gasify it into methanol-water mixed steam, and provide the heat required for the reforming reaction of the methanol-water mixed steam, but uses a phase change energy storage molten salt reactor to provide heat, thereby reducing the consumption of raw methanol, increasing the hydrogen production of raw methanol, and improving economic benefits, so as to overcome the shortcomings of the prior art. Efficient thermal management, reaction control and gas separation in the process of methanol reforming hydrogen production are achieved.

[0016] In order to achieve the above object, the technical solution adopted by the present invention is: A methanol reforming hydrogen production system, comprising a methanol-water mixing module, a molten salt phase change energy storage module, a reforming reaction module and a post-processing module which are sequentially connected and arranged; The molten salt phase-change energy storage module includes a phase-change energy storage molten salt pile and a molten salt pile heat release device 1 and a molten salt pile heat release device 2 arranged inside the phase-change energy storage molten salt pile. The output end of the methanol-water mixing module is connected to the molten salt pile heat release device 1, and the output end of the molten salt pile heat release device 1 is connected to the reforming reaction module. The reforming reaction module includes a reforming reactor with a built-in axial heating tube bundle, a catalytic reaction chamber is formed between the tubes of the axial heating tube bundle, and the inner channel of the tube of the axial heating tube bundle and the molten salt reactor heat release device 2 form a circulation loop, and a heat transfer medium is arranged in the circulation loop to provide the heat absorbed during the methanol reforming hydrogen production reaction; The post-processing module separates and collects the gas generated by the reaction in the reforming reaction module.

[0017] Furthermore, the methanol-water mixing module includes a clean water raw material tank and a methanol raw material tank arranged at the input end of the mixer, and a mixed liquid buffer tank arranged at the output end of the mixer; the output end of the mixed liquid buffer tank is connected to the molten salt reactor heat release device 1.

[0018] Furthermore, the molten salt reactor heat release device 1 includes a steam drum, a downcomer, an upper header pipe, an ascending pipe and a lower header pipe arranged in sequence from top to bottom, the ascending pipe is arranged in the phase change energy storage molten salt reactor, and the output end of the mixed liquid buffer tank is connected to the steam drum; After the methanol-water mixture is fed into the steam drum, it flows from the downcomer to the lower header pipe, and then enters the riser. After absorbing the heat stored in the phase change energy storage molten salt reactor in the riser, a part of the methanol-water mixture is vaporized into methanol-water mixed steam. After the steam-liquid mixture in the riser enters the steam drum, the steam-liquid separation is carried out in the steam drum. The methanol-water mixed steam leaves from the outlet pipe at the top of the steam drum and is transported to the reforming reactor.

[0019] Furthermore, the second molten salt reactor heat release device includes a group of tube rows, upper header tubes and lower header tubes. The tube rows are arranged in the phase change energy storage molten salt reactor. After the heat transfer medium in the heat transfer medium buffer tank enters the lower header tube, it flows upward along the tube rows and absorbs the heat stored in the phase change energy storage molten salt reactor, and then gathers to the upper header tube and leaves from the outlet pipe on the upper header tube; and then is transported to the axial heating tube bundle; the output end of the axial heating tube bundle is connected to the heat transfer medium buffer tank.

[0020] Furthermore, the heat transfer medium is heat transfer oil or liquid water.

[0021] Furthermore, the reforming reactor includes a pressure shell, an upper tube plate, a lower tube plate, and an axial heating tube bundle, a catalyst grid and a catalyst pressure grid arranged between the upper tube plate and the lower tube plate; the upper tube plate, the lower tube plate, the catalyst grid and the catalyst pressure grid are arranged in parallel in the pressure shell, the axial heating tube bundle is a group of straight tubes, and the two ends of each straight tube pass through the corresponding tube holes on the upper tube plate and the lower tube plate respectively and are welded to the upper tube plate and the lower tube plate, and the outer edges of the upper tube plate and the lower tube plate are welded to the inner wall of the pressure shell.

[0022] The catalyst is filled between the catalyst grid and the catalyst pressure grid; the catalyst is a copper-based catalyst.

[0023] Furthermore, the post-processing module includes a condenser, a gas separator and a gas collecting tank which are sequentially arranged at the gas outlet of the reforming reactor. Cooling water is introduced into the cooling channel of the condenser, and the unreacted methanol-water mixed vapor in the gas fed into the condenser is condensed into a methanol-water mixed liquid and returned to the mixed liquid buffer tank. The mixed gas after cooling by the condenser is separated in the gas separator and collected in the gas collecting tank.

[0024] The second object of the present invention is to provide a control method for a methanol reforming hydrogen production system, which couples the methanol reforming hydrogen production process with molten salt phase change energy storage, and uses a phase change energy storage molten salt reactor to provide heat to heat the raw materials and catalysts for reforming hydrogen production. A built-in axial heating tube bundle methanol reforming reactor is used to cause the methanol-water mixed steam to undergo a reforming reaction in the reforming reactor to generate hydrogen and carbon dioxide. During the process, the temperature of the catalyst is kept constant to ensure the efficiency and stability of the methanol reforming reaction.

[0025] In order to achieve the above object, the technical solution adopted by the present invention is: A control method for a methanol reforming hydrogen production system comprises the following steps: S01: Purified water and methanol are pumped into the mixer at a molar ratio of 1:0.9 to 1:1.5 respectively, and the mixed methanol-water mixture is transported to the mixed liquid buffer tank, and then pumped to the molten salt reactor heat release device 1; S02: Molten salt reactor heat release device - absorbs the heat provided by the phase change energy storage molten salt reactor, heats and vaporizes the methanol-water mixture, and makes the outlet temperature of the methanol-water mixed steam between 200℃ and 280℃, and then sends the methanol-water mixed steam into the catalytic reaction chamber; S03: The second molten salt reactor heat release device absorbs the heat provided by the phase change energy storage molten salt reactor to heat the heat transfer medium. The heat transfer medium pump circulates to control the flow of the heat transfer medium. According to the feedback information from the reactor temperature sensor, the heat output of the heating tube bundle is adjusted to ensure that the catalyst temperature is constant at 200℃~280℃; S04: The mixed steam enters the reforming reactor from below the catalyst, then passes upward through the gaps between the catalysts, and undergoes a reforming reaction under the action of the catalyst to generate hydrogen and carbon dioxide; S05: The mixed gas at the outlet of the reforming reactor is condensed and separated to obtain hydrogen and carbon dioxide, and the hydrogen is introduced into a hydrogen collection tank, and the carbon dioxide is introduced into a carbon dioxide collection tank.

[0026] Furthermore, a temperature sensor is arranged in the catalyst reaction chamber to monitor the catalyst temperature in real time; if the temperature is lower than the set value, the system can increase the circulation speed of the heat transfer medium; if the temperature is too high, the circulation speed is reduced or the heat transfer amount is reduced.

[0027] Furthermore, in step S05, the mixed gas at the outlet of the reforming reactor is introduced into a condenser, and cooling water is introduced to control the temperature of the condenser to ensure that the unreacted methanol-water mixed vapor is condensed into liquid and returned to the raw material buffer tank. The cooled mixed gas enters a gas separator to separate hydrogen and carbon dioxide, and the hydrogen enters a hydrogen collection tank, while the carbon dioxide is introduced into a carbon dioxide collection tank.

[0028] The beneficial effects of the present invention are: The present invention overcomes the problem of unstable catalyst temperature in the traditional hydrogen production process by combining phase change energy storage and efficient heating medium circulation loop, and fundamentally improves the reaction efficiency, hydrogen production and purity of the system. The thermal stability of the phase change energy storage module and the precise control of the heat transfer medium cycle complement each other, providing a constant and ideal temperature environment for the catalyst; effectively solving the adverse effects of temperature fluctuations on the reaction, making the system's hydrogen production process more efficient, energy-saving and stable.

[0029] The present invention arranges a molten salt pile heat release device 1 and a molten salt pile heat release device 2 in a phase change energy storage molten salt pile, wherein the molten salt pile heat release device 1 is connected to the output end of the methanol-water mixing module, and is used to heat and gasify the methanol-water mixture. The molten salt pile heat release device 2 forms a circulation loop with the axial heating tube bundle in the reforming reactor, and transfers heat to maintain the temperature required for the reforming reaction. The present invention utilizes the high heat capacity characteristics of the phase change energy storage material, and can efficiently store and release heat under relatively constant temperature conditions, thereby solving the problems of high energy consumption and difficult stable temperature control in traditional heating methods.

[0030] The condenser in the post-processing module condenses the unreacted methanol-water vapor into liquid and returns it to the mixed liquid buffer tank, further reducing the waste of raw materials and improving the utilization rate of methanol and water. This solves the problem of unreacted raw materials being easily discharged and wasted in traditional hydrogen production systems, effectively reducing operating costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0032] Figure 1 This is a schematic diagram of the structure of a methanol reforming hydrogen production system according to an embodiment of the present invention; Figure 2 This is a schematic diagram of the structure of a molten salt phase change energy storage module in an embodiment of the present invention; Figure 3 Schematic diagram of the structure of the reforming reactor in an embodiment of the present invention.

[0033] Figure numerals: 10, methanol-water mixing module; 11, water purification raw material tank; 12, methanol raw material tank; 13, mixer; 14, mixed liquid buffer tank; 20, molten salt phase change energy storage module; 21, phase change energy storage molten salt reactor; 22, molten salt reactor heat release device one; 221, steam drum; 222, downcomer; 223, upper header pipe; 224, riser; 225, lower header pipe; 23, molten salt reactor heat release device two; 231, pipe row; 232, upper header pipe; 233, lower header pipe; 30, reforming reaction module; 31, reforming reactor ; 311, pressure shell; 312, upper tube sheet; 313, lower tube sheet; 314, catalyst rack; 315, catalyst pressure grid; 316, heat transfer medium inlet; 317, heat transfer medium outlet; 318, raw gas inlet; 319, reaction gas outlet; 320, catalyst loading inlet; 321, catalyst unloading outlet; 322, heat transfer medium buffer tank; 32, axial heating tube bundle; 33, catalytic reaction chamber; 40, post-processing module; 41, condenser; 42, gas separator; 43, hydrogen collection tank; 44, carbon dioxide collection tank. DETAILED DESCRIPTION

[0034] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0035] It should be noted that when an element is referred to as being "fixed to" another element, it may be directly on the other element or there may be a central element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be a central element at the same time. The terms "vertical", "horizontal", "left", "right" and similar expressions used herein are for illustrative purposes only and do not represent the only implementation method.

[0036] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0037] The present invention introduces a phase-change energy storage molten salt pile 21, and forms a closed-loop heating medium circulation circuit with a heat release device and an axial heating tube bundle 32, thereby achieving significant improvements in the following aspects: Thermal stability of phase change energy storage: Phase change energy storage materials can continuously release or absorb heat at the phase change temperature to maintain a relatively constant temperature. This feature greatly reduces the temperature fluctuations caused by traditional heating sources, allowing the system to provide a stable heat supply during long-term operation; through the design of phase change energy storage modules and heat transfer fluids, the system can absorb excess heat during the heating process to prevent the temperature from rising too quickly, thereby avoiding the risk of catalyst deactivation due to overheating.

[0038] High-efficiency circulation loop design: By forming a closed circulation loop with the heat release device 2 in the phase change energy storage molten salt reactor 21 and the axial heating tube bundle 32, the heat transfer medium circulates in the pipeline at a stable flow rate, and evenly transfers the heat of the energy storage material to the reforming reactor 31. The temperature sensor and feedback control system configured in the circulation loop monitors the catalyst temperature in real time, and automatically adjusts the flow rate or heat exchange amount of the heat transfer medium when the temperature deviates from the set value, thus ensuring the constancy of the catalyst temperature and improving the reaction efficiency and hydrogen production.

[0039] Precise control of catalyst temperature: Through heat transfer in the circulation loop, the catalyst inside the axial heating tube bundle 32 is heated evenly, and the temperature can be strictly controlled within the ideal range of 200°C to 280°C, thereby significantly improving the efficiency of the methanol reforming reaction; constant temperature avoids drastic temperature fluctuations of the catalyst, which is particularly important for sensitive copper-based catalysts. The temperature stability in the present invention not only increases the service life of the catalyst, but also reduces the generation of by-products and improves the purity of hydrogen.

[0040] Example 1 like Figure 1 A methanol reforming hydrogen production system shown includes a methanol-water mixing module 10, a molten salt phase change energy storage module 20, a reforming reaction module 30 and a post-processing module 40 which are sequentially connected; The methanol-water mixing module 10 includes a purified water raw material tank 11 and a methanol raw material tank 12 arranged at the input end of a mixer 13, and a mixed liquid buffer tank 14 arranged at the output end of the mixer 13; the output end of the mixed liquid buffer tank 14 is connected to a molten salt reactor heat release device 22.

[0041] The molten salt phase change energy storage module 20 includes a phase change energy storage molten salt pile 21 and a molten salt pile heat release device 1 22 and a molten salt pile heat release device 2 23 arranged inside the phase change energy storage molten salt pile 21. The output end of the methanol-water mixing module 10 is connected to the molten salt pile heat release device 1 22, and the output end of the molten salt pile heat release device 1 22 is connected to the reforming reaction module 30. The molten salt pile heat release device 1 22 is connected to the output end of the methanol-water mixing module 10, and is used to heat and gasify the methanol-water mixture. The molten salt pile heat release device 2 23 forms a circulation loop with the axial heating tube bundle 32 in the reforming reactor 31, and transfers heat to maintain the temperature required for the reforming reaction. The present invention adopts methanol reforming to produce hydrogen on a large scale in a fixed occasion, solves the heat required for heating and gasifying the methanol-water mixture into methanol-water mixed steam, and provides the source of heat required for the reforming reaction of methanol-water mixed steam, so as to reduce the consumption of raw material methanol, increase the hydrogen production of raw material methanol, and improve the economic benefits. On this basis, the present invention couples molten salt phase change energy storage, and can use the low-price valley electricity of the power grid during the valley period to store heat, which not only plays the role of peak shaving and valley filling for the power grid, but also uses the low-price valley electricity to store heat, which can further reduce the cost of methanol reforming hydrogen production. In addition, in areas rich in photovoltaic and wind power, molten salt phase change energy storage can absorb a large amount of unstable new energy abandonment such as photovoltaic and wind power that the power grid cannot accept, reducing energy waste.

[0042] like Figure 2 As shown, the molten salt reactor heat release device 22 includes a steam drum 221, a downcomer 222, an upper header pipe 223, an ascending pipe 224 and a lower header pipe 225 arranged in sequence from top to bottom. The ascending pipe 224 is arranged in the phase change energy storage molten salt reactor 21, and the output end of the mixed liquid buffer tank 14 is connected to the steam drum 221; After the methanol-water mixture is fed into the steam drum 221, it flows from the downcomer 222 to the lower header pipe 225, and then enters the riser 224. After absorbing the heat stored in the phase change energy storage molten salt reactor 21 in the riser 224, a part of the methanol-water mixture is vaporized into methanol-water mixed steam. After the steam-liquid mixture in the riser 224 enters the steam drum 221, the steam-liquid separation is performed in the steam drum 221, wherein the methanol-water mixed steam leaves from the outlet pipe at the top of the steam drum 221 and is then transported to the reforming reactor 31. This design improves the heat exchange efficiency of the molten salt reactor heat release device 22, and ensures the quality of the steam and the reaction effect.

[0043] Among them, the steam drum 221 of the molten salt reactor heat release device 22 is also a pressure container. The steam drum 221, the downcomer 222 and the riser 224 are a set of pressure units, and together with the reforming reactor 31, they form a pressure system through process pipelines.

[0044] On this basis, the molten salt reactor heat release device 23 includes a group of tube rows 231, an upper header tube 232 and a lower header tube 233. The tube row 231 is arranged in the phase change energy storage molten salt reactor 21. After the heat transfer medium in the heat transfer medium buffer tank 322 enters the lower header tube 233, it flows upward along the tube row 231 and absorbs the heat stored in the phase change energy storage molten salt reactor 21, and then gathers to the upper header tube 232, and leaves from the outlet pipe on the upper header tube 232; and then is transported to the axial heating tube bundle 32; the output end of the axial heating tube bundle 32 is connected to the heat transfer medium buffer tank 322.

[0045] Preferably, the heat transfer medium is heat transfer oil or liquid water. When the heat transfer medium is liquid water, the liquid water absorbs the heat stored in the molten salt reactor in the molten salt reactor heat release device 23 and vaporizes into water vapor. In order to make the water vapor have a higher density and obtain a better heating effect, the water vapor must also be operated at a higher pressure, so the heat transfer medium circulation loop is also a pressure-bearing system.

[0046] like Figure 3 As shown, the reforming reaction module 30 includes a reforming reactor 31 with a built-in axial heating tube bundle 32, a catalytic reaction chamber 33 is formed between the tubes of the axial heating tube bundle 32, and the tube channel of the axial heating tube bundle 32 and the molten salt reactor heat release device 23 form a circulation loop, and a heat transfer medium is provided in the circulation loop to provide the heat absorbed during the methanol reforming hydrogen production reaction; The reforming reactor 31 is a pressure-bearing container, comprising a pressure-bearing shell 311, an upper tube sheet 312, a lower tube sheet 313, and an axial heating tube bundle 32, a catalyst grid 314 and a catalyst pressure grid 315 arranged between the upper tube sheet 312 and the lower tube sheet 313; the upper tube sheet 312, the lower tube sheet 313, the catalyst grid 314 and the catalyst pressure grid 315 are arranged in parallel in the pressure-bearing shell 311, and a catalyst is filled between the catalyst grid 314 and the catalyst pressure grid 315, the catalyst grid 314 is at the bottom, and the catalyst pressure grid 315 is at the top, which is used to stabilize and fix the catalyst. The catalyst is a copper-based catalyst, which has good activity for the reforming reaction of methanol and can effectively convert methanol and water mixed steam into hydrogen and carbon dioxide at a relatively low temperature. On this basis, when the temperature of the catalyst is relatively stable, the content of by-products produced by the reaction is extremely small, and the purity of the carbon dioxide gas finally separated is very high, and can be directly used as a raw material for other industrial production.

[0047] The advantages of adopting a pressure vessel structure for the reforming reactor 31 are as follows: the volume and size of the reforming reactor 31 can be greatly reduced, because the temperature at which the reforming reaction of the methanol-water mixed steam occurs is above 200°C, which is much higher than the standard boiling points of methanol and water. The density of the gas is very small under normal pressure. If normal pressure operation is adopted, in order to achieve a certain production capacity, the required volume and size of the reforming reactor 31 will be very large, and a large amount of metal materials will be consumed; and above 200°C, methanol and water have a higher saturated vapor pressure, so as long as the operating pressure is not greater than the saturated vapor pressure, the material is always in a gaseous state, and the density of steam under higher pressure is much greater than that of steam under normal pressure. Therefore, for the same production capacity, the reforming reactor 31 adopts a pressure vessel structure, and its volume and size can be greatly reduced, which can not only reduce the consumption of metal materials, but also reduce the floor space.

[0048] The axial heating tube bundle 32 is a group of straight tubes. The two ends of each straight tube pass through the corresponding tube holes on the upper tube sheet 312 and the lower tube sheet 313 and are welded to the upper tube sheet 312 and the lower tube sheet 313. The outer edges of the upper tube sheet 312 and the lower tube sheet 313 are welded to the inner wall of the pressure shell 311. The upper and lower temperature difference of the axial heating tube bundle 32 is less than 0.5°C, which can maintain a highly stable temperature in the reaction area. Avoid the reduction of catalyst activity that may be caused by temperature fluctuations, thereby ensuring hydrogen production and product purity. The constant temperature allows the catalyst to operate continuously within the optimal temperature range, reduces catalyst degradation caused by overheating or temperature fluctuations, can delay the deactivation of the catalyst, extend its service life, and reduce the maintenance and replacement costs of the equipment.

[0049] Both ends of each straight tube are firmly welded to the tube sheet, and the outer edges of the upper tube sheet 312 and the lower tube sheet 313 are welded to the pressure shell 311 to form an overall strong structure. This improves the sealing of the system, enhances the mechanical stability of the pressure shell 311, prolongs the life of the equipment, and enables it to operate safely under higher pressure.

[0050] The axial heating tube bundle 32 is adopted, and the tube bundle is a group of straight tubes, which has the following advantages: because the tube bundle in the catalytic reaction chamber 33 is evenly distributed, the heat transfer medium is evenly distributed in each straight tube, the flow resistance is small, and the heat transfer is stable, so the heat transfer medium in the heating tube bundle has the same heating effect on the catalyst in each area, the temperature of the catalyst on the cross section in the reaction chamber is relatively uniform, and when the methanol-water mixed steam passes through the catalyst, the reaction rate of each area on the cross section is relatively stable; in addition, the heat transfer medium enters from the upper part of the reforming reactor 31 and flows out from the lower part, so the temperature of the upper part of the catalytic reaction chamber 33 is higher than that of the lower part, which is conducive to a more complete reforming reaction of the methanol-water mixed steam, because the raw gas enters the catalytic reaction chamber 33 from the lower part and starts to react, the content of the raw gas in the gas gradually decreases, and when the gas flows to the upper part of the catalytic reaction chamber 33, the content of the raw gas in the gas is relatively small, and the temperature of the upper part is high, which is conducive to the reaction, making the reaction more complete, and can increase the hydrogen content in the reaction gas, thereby improving production efficiency.

[0051] The reforming reactor 31 further includes a heat transfer medium inlet 316, a heat transfer medium outlet 317, a raw gas inlet 318, a reaction gas outlet 319, a catalyst loading inlet 320, and a catalyst unloading outlet 321; wherein the heat transfer medium inlet 316 is arranged at the upper part of the reforming reactor 31, and is used to connect to the outlet pipe on the upper header pipe 232, the heat transfer medium outlet 317 is arranged at the lower part of the reforming reactor 31, and is used to connect to the heat transfer medium buffer tank 322, the raw gas inlet 318 is connected to the outlet pipe at the top of the drum 221, and the reaction gas outlet 319 is connected to the outlet pipe at the top of the drum 221. 319 is connected to the condenser 41, and the catalyst loading port 320, the catalyst unloading port 321, the raw gas inlet 318 and the reaction gas outlet 319 are all arranged on the side wall of the reforming reactor 31, and the height of the reaction gas outlet 319 is greater than the height of the catalyst loading port 320> the height of the catalyst unloading port 321> the height of the raw gas inlet 318, which ensures the natural inclination of the gas flow, reduces the possibility of liquid retention and gas reflux, thereby avoiding the problem of uneven gas mixing in the reactor and improving the safety of the overall system.

[0052] Please continue to refer to Figure 1 The post-processing module 40 separates and collects the gas generated by the reaction in the reforming reaction module 30, which not only improves the recovery rate of the reactants and the purity of hydrogen, but also enhances the safety and economy of the system.

[0053] The post-processing module 40 includes a condenser 41, a gas separator 42 and a gas collection tank which are sequentially arranged at the gas outlet of the reforming reactor 31. Cooling water is introduced into the cooling channel of the condenser 41 to condense the unreacted methanol-water mixed steam in the gas fed into the condenser 41 into a methanol-water mixed liquid and return it to the mixed liquid buffer tank 14 for recycling. The gas separator 42 is arranged after the condenser 41 and is responsible for further processing the condensed gas. The mixed gas cooled by the condenser 41 is separated in the gas separator 42 and collected in the gas collection tank.

[0054] Example 2 A control method for a methanol reforming hydrogen production system comprises the following steps: S01: According to the molar ratio of 1:0.9 to 1:1.5, the purified water and methanol are pumped into the mixer 13 respectively, and the mixed methanol-water mixture is transported to the mixed liquid buffer tank 14, and then pumped to the molten salt reactor heat release device 22; through accurate molar ratio control, the reaction conditions can be optimized and the hydrogen yield can be improved. At the same time, the setting of the buffer tank ensures the stable supply of the mixed liquid and reduces the load on subsequent equipment; S02: The molten salt reactor heat release device 22 absorbs the heat provided by the phase change energy storage molten salt reactor 21, heats and vaporizes the methanol-water mixture, and makes the outlet temperature of the methanol-water mixed steam between 200°C and 280°C, and then sends the methanol-water mixed steam into the catalytic reaction chamber 33; this step ensures the complete vaporization of the mixed liquid, provides the required gaseous raw materials for the catalytic reaction, and controlling the outlet temperature can optimize the efficiency of subsequent reactions; S03: The molten salt reactor heat release device 23 absorbs the heat provided by the phase change energy storage molten salt reactor 21 to heat the heat transfer medium. The heat transfer medium pump circulates to control the flow rate of the heat transfer medium. According to the feedback information from the reactor temperature sensor, the heat output of the heating tube bundle is adjusted to ensure that the catalyst temperature is constant at 200°C~280°C. Furthermore, a temperature sensor is arranged in the catalyst reaction chamber to monitor the catalyst temperature in real time; if the temperature is lower than the set value, the system can increase the circulation speed of the heat transfer medium; if the temperature is too high, the circulation speed is reduced or the heat transfer amount is reduced. The information fed back by the temperature sensor enables the system to adjust in real time to ensure that the catalyst temperature is within the optimal range, thereby improving the reaction efficiency and stability; S04: The mixed steam enters the reforming reactor 31 from below the catalyst, then passes upward through the gaps of the catalyst, and undergoes a reforming reaction under the action of the catalyst to generate hydrogen and carbon dioxide. The up-and-down flow design ensures that the mixed steam is fully in contact with the catalyst, thereby increasing the conversion rate of the reaction. S05: The mixed gas at the outlet of the reforming reactor 31 is introduced into the condenser 41, and cooling water is introduced to control the temperature of the condenser 41 to ensure that the unreacted methanol-water mixed steam is condensed into liquid and returned to the raw material buffer tank. The cooled mixed gas enters the gas separator 42 to separate hydrogen and carbon dioxide. There is a diaphragm in the gas separator 42, through which only hydrogen molecules can pass, and other gas molecules cannot pass, so the hydrogen in the mixed gas can be separated. The separated hydrogen enters the hydrogen collection tank 43, and the carbon dioxide is introduced into the carbon dioxide collection tank 44.

[0055] In the present invention, the catalyst temperature is precisely adjusted in the reforming reactor 31 by axially heating the tube bundle 32 and the heat transfer medium circulation system, combined with the feedback control of the temperature sensor. This control method solves the problem that the catalyst temperature is difficult to maintain constant, and the reaction temperature is maintained at 200°C to 280°C, thereby ensuring the efficiency and stability of the methanol reforming reaction.

[0056] The condenser 41 in the post-processing module 40 condenses the unreacted methanol-water vapor into liquid and returns it to the mixed liquid buffer tank 14, further reducing the waste of raw materials and improving the utilization rate of methanol and water. The problem of unreacted raw materials being easily discharged and wasted in the traditional hydrogen production system is solved, and the operating cost is effectively reduced.

[0057] The present invention realizes the high efficiency, safety and controllability of the methanol reforming hydrogen production process through strict steps and real-time adjustment mechanism, optimizes the utilization of raw materials, improves the reaction efficiency, and ensures the purity of the final product, providing effective guarantee for large-scale hydrogen production.

[0058] Those skilled in the art should understand that the present invention is not limited to the above embodiments, and the above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, and these changes and improvements fall within the scope of the present invention to be protected. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A methanol reforming hydrogen production system, characterized in that: It includes a methanol-water mixing module, a molten salt phase change energy storage module, a reforming reaction module and a post-processing module which are connected in sequence; The molten salt phase-change energy storage module comprises a phase-change energy storage molten salt pile and a molten salt pile heat release device 1 and a molten salt pile heat release device 2 arranged inside the phase-change energy storage molten salt pile, the output end of the methanol-water mixing module is connected to the molten salt pile heat release device 1, and the output end of the molten salt pile heat release device 1 is connected to the reforming reaction module; The reforming reaction module comprises a reforming reactor with a built-in axial heating tube bundle, a catalytic reaction chamber is formed between the tubes of the axial heating tube bundle, the inner channel of the tube of the axial heating tube bundle and the second molten salt reactor heat release device form a circulation loop, and a heat transfer medium is arranged in the circulation loop to provide heat absorbed during the methanol reforming hydrogen production reaction; The post-processing module separates and collects the gas generated by the reaction in the reforming reaction module.

2. A methanol reforming hydrogen production system according to claim 1, characterized in that: The methanol-water mixing module includes a clean water raw material tank and a methanol raw material tank arranged at the input end of the mixer, and a mixed liquid buffer tank arranged at the output end of the mixer; the output end of the mixed liquid buffer tank is connected to the molten salt reactor heat release device 1.

3. A methanol reforming hydrogen production system according to claim 1, characterized in that: The molten salt reactor heat release device 1 includes a steam drum, a downcomer, an upper header pipe, an ascending pipe and a lower header pipe arranged in sequence from top to bottom, the ascending pipe is arranged in the phase change energy storage molten salt reactor, and the output end of the mixed liquid buffer tank is connected to the steam drum; After the methanol-water mixture is fed into the steam drum, it flows from the downcomer to the lower header pipe, and then enters the riser. After absorbing the heat stored in the phase change energy storage molten salt reactor in the riser, a part of the methanol-water mixture is vaporized into methanol-water mixed steam. After the steam-liquid mixture in the riser enters the steam drum, steam-liquid separation is performed in the steam drum, and the methanol-water mixed steam leaves from the outlet pipe at the top of the steam drum and is transported to the reforming reactor.

4. A methanol reforming hydrogen production system according to claim 1, characterized in that: The second molten salt reactor heat release device includes a group of tube rows, upper header tubes and lower header tubes. The tube rows are arranged in the phase change energy storage molten salt reactor. After the heat transfer medium in the heat transfer medium buffer tank enters the lower header tube, it flows upward along the tube rows and absorbs the heat stored in the phase change energy storage molten salt reactor, and then gathers to the upper header tube and leaves from the outlet pipe on the upper header tube; and then is transported to the axial heating tube bundle; the output end of the axial heating tube bundle is connected to the heat transfer medium buffer tank.

5. A methanol reforming hydrogen production system according to claim 4, characterized in that: The heat transfer medium is heat-conducting oil or liquid water.

6. A methanol reforming hydrogen production system according to claim 1, characterized in that: The reforming reactor comprises a pressure shell, an upper tube sheet, a lower tube sheet, and an axial heating tube bundle, a catalyst grid and a catalyst pressure grid arranged between the upper tube sheet and the lower tube sheet; the upper tube sheet, the lower tube sheet, the catalyst grid and the catalyst pressure grid are arranged in parallel in the pressure shell, the axial heating tube bundle is a group of straight tubes, the two ends of each straight tube respectively pass through the corresponding tube holes on the upper tube sheet and the lower tube sheet and are welded to the upper tube sheet and the lower tube sheet, and the outer edges of the upper tube sheet and the lower tube sheet are welded to the inner wall of the pressure shell.

7. A methanol reforming hydrogen production system according to claim 2, characterized in that: The post-processing module includes a condenser, a gas separator and a gas collection tank which are sequentially arranged at the gas outlet of the reforming reactor. Cooling water is introduced into the cooling channel of the condenser to condense the unreacted methanol-water mixed steam in the gas fed into the condenser into a methanol-water mixed liquid and return it to the mixed liquid buffer tank. The mixed gas cooled by the condenser is separated in the gas separator and collected in the gas collection tank.

8. A control method for a methanol reforming hydrogen production system, characterized in that: The steps include: S01: Purified water and methanol are pumped into the mixer at a molar ratio of 1:0.9 to 1:1.5 respectively, and the mixed methanol-water mixture is transported to the mixed liquid buffer tank, and then pumped to the molten salt reactor heat release device 1; S02: the molten salt reactor heat release device absorbs the heat provided by the phase change energy storage molten salt reactor, heats and vaporizes the methanol-water mixed liquid, and makes the outlet temperature of the methanol-water mixed steam between 200° C. and 280° C., and then sends the methanol-water mixed steam into the catalytic reaction chamber; S03: The second molten salt reactor heat release device absorbs the heat provided by the phase change energy storage molten salt reactor to heat the heat transfer medium. The heat transfer medium pump circulates to control the flow rate of the heat transfer medium. According to the feedback information of the reactor temperature sensor, the heat output of the heating tube bundle is adjusted to ensure that the catalyst temperature is constant at 200°C~280°C; S04: the mixed steam enters the reforming reactor from below the catalyst, then passes upward through the gaps of the catalyst, and undergoes a reforming reaction under the action of the catalyst to generate hydrogen and carbon dioxide; S05: The mixed gas at the outlet of the reforming reactor is condensed and separated to obtain hydrogen and carbon dioxide, and the hydrogen is introduced into a hydrogen collection tank, and the carbon dioxide is introduced into a carbon dioxide collection tank.

9. The control method of a methanol reforming hydrogen production system according to claim 8, characterized in that: A temperature sensor is arranged in the catalyst reaction chamber to monitor the catalyst temperature in real time; if the temperature is lower than the set value, the system can increase the circulation speed of the heat transfer medium; if the temperature is too high, the circulation speed is reduced or the heat transfer amount is reduced.

10. The control method of a methanol reforming hydrogen production system according to claim 8, characterized in that: In step S05, the mixed gas at the outlet of the reforming reactor is introduced into a condenser, and cooling water is introduced to control the temperature of the condenser to ensure that the unreacted methanol-water mixed vapor is condensed into liquid and returned to the raw material buffer tank. The cooled mixed gas enters a gas separator to separate hydrogen and carbon dioxide. The hydrogen enters a hydrogen collection tank, and the carbon dioxide is introduced into a carbon dioxide collection tank.

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