A marine methanol steam reforming system and method integrated with exhaust gas driving and phase change heat storage

Abstract

This invention relates to the field of marine energy and chemical engineering technology. It discloses a methanol vapor reforming system and method integrating marine exhaust gas drive and phase change thermal storage. The system includes an integrated phase change thermal storage reactor, a methanol / water storage tank, a mixer, and a bypass control valve. The reactor integrates a two-stage phase change thermal storage module: a low-temperature phase change thermal storage evaporation zone for vaporizing the methanol / water mixture, and a high-temperature phase change thermal storage reaction zone for maintaining a constant temperature for the reforming reaction. Engine exhaust gas flows sequentially through the high-temperature and low-temperature zones, achieving cascaded energy utilization. The bypass control valve regulates the intake air volume. When exhaust gas fluctuates, the system preferentially consumes the latent heat of the phase change material to stabilize the device temperature. This invention, through functional integration and a two-stage phase change thermal storage design, effectively solves the problem of unstable hydrogen production caused by fluctuations in marine exhaust gas temperature during reforming. It achieves efficient cascaded recovery of waste heat, stable hydrogen production, and highly compact equipment, making it particularly suitable for the space-constrained and variable operating conditions of marine environments.

Description

Technical Field

[0001] This invention relates to the field of marine energy and chemical engineering technology, specifically to a system for producing hydrogen by using waste heat from marine engine exhaust to drive methanol steam reforming, and more particularly to a system and method that integrates waste heat recovery, phase change heat storage and methanol reforming reaction functions. Background Technology

[0002] With increasingly stringent regulations on greenhouse gas and pollutant emissions in the global shipping industry, such as the International Maritime Organization's (IMO) Tier III standard, finding clean and efficient marine propulsion solutions has become an urgent need within the industry. Methanol vapor reforming (MSR) hydrogen production technology demonstrates significant application potential in this context. This technology can convert liquid methanol and water into hydrogen-rich gas (mainly composed of H2 and CO2), and its specific applications and value are reflected in:

[0003] Firstly, it enables in-situ hydrogen production on ships, thereby avoiding the safety risks, high costs, and space occupation issues associated with directly storing high-pressure or low-temperature liquid hydrogen, making the application of hydrogen power on ships more feasible.

[0004] Secondly, the reaction is a mesothermal endothermic process (usually 200-300℃), which can utilize the high-temperature exhaust gas (usually over 300℃) from the ship's engine as a heat source to convert the waste heat that would otherwise be emitted into the environment into high-grade chemical energy (chemical energy of hydrogen), significantly improving the overall energy utilization efficiency of the entire ship's power system.

[0005] Third, the produced hydrogen can be mixed into the engine intake or cylinder, and by utilizing the excellent combustion characteristics of hydrogen (such as fast flame propagation speed and short quenching distance), the combustion process of the engine can be improved to achieve lean combustion. This effectively suppresses the generation of nitrogen oxides (NOx) without sacrificing power performance, which is one of the key technical paths for marine engines to meet emission regulations.

[0006] However, despite the promising prospects of the aforementioned technological concepts, the practical application of methanol steam reforming technology in actual marine environments still faces the following technical challenges, which severely restrict its commercial application:

[0007] First, traditional methanol steam reforming systems typically use electric heating or combustion of part of the methanol feedstock to provide the heat required for the reaction. This directly leads to low "energy input-output" efficiency of the system and may even require the consumption of precious fuel, which goes against the original intention of energy conservation and efficiency improvement.

[0008] Secondly, the operating conditions of ship engines are extremely complex and variable, and frequent load changes directly lead to drastic fluctuations in exhaust gas temperature and flow rate. Furthermore, the methanol steam reforming reaction is extremely sensitive to temperature, requiring the catalyst to maintain high activity and selectivity within a relatively narrow and stable temperature window (e.g., 220-260℃). Existing waste heat recovery systems are mostly single heat exchangers, lacking effective thermal buffering and management capabilities. When the exhaust gas temperature drops sharply, the reactor temperature decreases rapidly, leading to a drastic deterioration in hydrogen production rate and efficiency; conversely, when the exhaust gas temperature rises sharply, it may cause catalyst sintering and deactivation, resulting in extremely poor system stability.

[0009] Furthermore, from an energy utilization perspective, the methanol reforming process comprises two stages with different thermodynamic characteristics: the first is the preheating, vaporization, and superheating of the methanol / water mixture (requiring a temperature of approximately 90-130℃), and the second is the methanol steam reforming reaction (requiring a temperature of approximately 220-260℃). Traditional solutions often indiscriminately heat the entire system, resulting in the waste of high-grade heat energy and failing to achieve "temperature matching and tiered utilization."

[0010] Finally, in order to complete a series of functions such as "heat exchange-vaporization-reaction-heat compensation", traditional process systems usually need to connect multiple independent devices in series, such as preheaters, evaporators, superheaters, reactors, heat exchangers, etc., resulting in the entire hydrogen production system being large in size, complex in structure, and numerous in pipelines. This creates a sharp contradiction with the reality that ship engine room space is extremely limited and the requirements for equipment compactness are extremely high.

[0011] Therefore, those skilled in the art urgently need a new technical solution that can integrate exhaust gas waste heat recovery, thermal energy storage and buffering, cascade thermal energy utilization and compact reforming reaction functions. Summary of the Invention

[0012] The core technical problem addressed by this invention is the lack of a methanol reforming hydrogen production thermal management technology that can simultaneously overcome the drastic temperature fluctuations of marine engine exhaust, achieve efficient cascade utilization of waste heat from exhaust gas, and meet the compactness requirements of ship platforms.

[0013] For those skilled in the art, without addressing this issue, it is impossible to successfully transfer and apply the relatively stable methanol reforming hydrogen production technology developed in laboratories or on land to the dynamic and harsh marine environment. Only by overcoming this technological bottleneck can we break through the dual predicament of "difficulty in hydrogen storage" and "high emissions" on ships, truly realize the use of existing methanol infrastructure to provide clean, stable, and efficient hydrogen power for ships, and thus provide a realistic and feasible technological path for the decarbonization process of the global shipping industry.

[0014] To address the aforementioned core technical issues, this invention presents a methanol vapor reforming system and method integrating marine exhaust gas drive and phase change thermal storage. The purpose is to employ an integrated two-stage phase change thermal storage reactor, utilizing phase change materials with different melting points to perform thermal management and tiered heating for the methanol vaporization section and the reforming reaction section, respectively.

[0015] To achieve the above objectives, the specific technical solution of the present invention is a methanol steam reforming system integrating marine exhaust gas drive and phase change thermal storage, comprising:

[0016] An integrated phase change thermal energy storage reactor, further comprising:

[0017] The low-temperature phase change thermal storage evaporation zone is filled with a first phase change material, the melting point of which is 90-130°C. The low-temperature phase change thermal storage evaporation zone is configured to receive a liquid methanol / water mixture and use the heat of the waste gas to heat and vaporize it into methanol / water vapor.

[0018] The high-temperature phase change thermal storage reaction zone is filled with a second phase change material, the melting point of which is 220-260°C. The high-temperature phase change thermal storage reaction zone is in fluid communication with the low-temperature phase change thermal storage evaporation zone and is configured to receive methanol / water vapor from the low-temperature phase change thermal storage evaporation zone and contain a reforming catalyst to carry out methanol vapor reforming reaction to generate hydrogen-rich reformed gas.

[0019] The exhaust gas passage passes sequentially through the high-temperature phase change heat storage reaction zone and the low-temperature phase change heat storage evaporation zone, and is used to guide the engine exhaust gas to first flow through the high-temperature phase change heat storage reaction zone to exchange heat with it, and then flow through the low-temperature phase change heat storage evaporation zone to exchange heat with it.

[0020] Methanol storage tanks and water storage tanks are used to store methanol and water, respectively;

[0021] A mixer is connected to the methanol storage tank and the water storage tank respectively, and is connected to the inlet of the low-temperature phase change thermal storage evaporation zone of the integrated phase change thermal storage reactor, for mixing methanol and water and supplying them to the integrated phase change thermal storage reactor.

[0022] A bypass control valve is installed on the exhaust gas pipeline between the engine and the integrated phase change thermal storage reactor to regulate the exhaust gas flow rate entering the integrated phase change thermal storage reactor.

[0023] In at least one embodiment, the integrated phase change thermal storage reactor further includes:

[0024] Main body shell;

[0025] The methanol reforming reaction pipeline is installed in the high-temperature phase change thermal storage reaction zone, and the reforming catalyst is installed inside the methanol reforming reaction pipeline.

[0026] A vaporization heat exchange pipe is installed in the low-temperature phase change thermal storage evaporation zone. The inlet of the vaporization heat exchange pipe is connected to the mixer, and the outlet is connected to the inlet of the methanol reforming reaction pipe.

[0027] In at least one embodiment, the high-temperature phase change thermal storage reaction zone further includes:

[0028] A high-temperature phase change material filling region is formed between the main outer shell and the methanol reforming reaction pipeline, which is used to fill the second phase change material;

[0029] A high-temperature exhaust gas heat exchange zone is formed between the inner wall of the main body shell and the high-temperature phase change material filling area. The high-temperature exhaust gas heat exchange zone is connected to the exhaust gas channel and is provided with one or more baffles and / or heat exchange fins to enhance the heat exchange between the exhaust gas and the high-temperature phase change material filling area.

[0030] In at least one embodiment, the low-temperature phase change thermal storage evaporation zone further includes:

[0031] A low-temperature phase change material filling region is formed between the main outer shell and the vaporization heat exchange pipe, which is used to fill the first phase change material;

[0032] A medium-temperature exhaust gas channel is formed between the inner wall of the main body shell and the low-temperature phase change material filling area. The medium-temperature exhaust gas channel is connected to the exhaust gas channel and is located around the vaporization heat exchange pipe.

[0033] In at least one embodiment, the system further includes a condensation recovery device and a reforming gas storage tank. The inlet of the condensation recovery device is connected to the reforming gas outlet of the integrated phase change thermal energy storage reactor, and its outlet is connected to the reforming gas storage tank for cooling and separating unreacted methanol and water in the reforming gas.

[0034] In at least one embodiment, the system has a first operating mode and a second operating mode;

[0035] One or more embodiments execute the first working mode. When the engine exhaust temperature or flow rate is higher than the rated value, the bypass control valve opens to the first opening degree, allowing part or all of the exhaust gas to enter the integrated phase change thermal storage reactor. The phase change materials in the high-temperature phase change thermal storage reaction zone and the low-temperature phase change thermal storage evaporation zone absorb excess heat and melt to store thermal energy.

[0036] In one or more embodiments, when the engine exhaust temperature or flow rate is lower than the rated value, the bypass control valve is adjusted to the second opening degree, and the phase change materials in the high-temperature phase change heat storage reaction zone and the low-temperature phase change heat storage evaporation zone release latent heat to maintain the temperature stability of the methanol vapor reforming reaction and the vaporization process of the methanol / water mixture.

[0037] In at least one embodiment, the melting point range of the first phase change material is preferably 90-120°C, and the melting point range of the second phase change material is preferably 220-260°C.

[0038] In at least one embodiment, the engine is a marine engine with an exhaust gas temperature of not less than 300°C.

[0039] In at least one embodiment, a method for methanol vapor reforming driven by marine exhaust gas and integrated with phase change thermal storage, the method being implemented based on the aforementioned system, includes the following steps:

[0040] (a) Methanol and water from the methanol storage tank and the water storage tank are mixed by the mixer to form a methanol / water mixture;

[0041] (b) The methanol / water mixture is introduced into the low-temperature phase change heat storage evaporation zone of the integrated phase change heat storage reactor, and the mixture is heated and vaporized into methanol / water vapor by the engine exhaust gas flowing through the zone and the latent heat released by the first phase change material.

[0042] (c) The methanol / water vapor is introduced into the high-temperature phase change thermal storage reaction zone of the integrated phase change thermal storage reactor. Under the action of the reforming catalyst, and using the latent heat released by the engine exhaust gas flowing through the zone and the second phase change material, an endothermic reforming reaction is carried out to generate hydrogen-rich reformed gas.

[0043] (d) The flow rate of the tail gas entering the integrated phase change thermal storage reactor is controlled by the bypass control valve. When the tail gas heat fluctuates, the latent heat of the first phase change material and the second phase change material is preferentially used to stabilize the reaction temperature.

[0044] In at least one embodiment, in steps (b) and (c), the engine exhaust gas flows sequentially through the high-temperature phase change thermal storage reaction zone and the low-temperature phase change thermal storage evaporation zone to achieve cascade utilization of heat.

[0045] In at least one embodiment, the method further includes step (e): passing the hydrogen-rich reformate into a condensation recovery device to separate and recover unreacted methanol and water therein, and then storing the purified reformate in a reformate storage tank.

[0046] In at least one embodiment, a computer-readable storage medium is provided, on which a computer program is stored, which, when executed by a processor, implements the steps of the method. Compared with the prior art, the technical solution disclosed in this application has the following non-obvious technical features:

[0047] First, this application features a high degree of functional-structural integration. Existing technologies typically connect waste gas heat exchangers, phase change heat storage devices, methanol evaporators, and reforming reactors as independent units in series. However, this application integrates the "low-temperature phase change heat storage and methanol / water evaporator," the "high-temperature phase change heat storage and reforming reactor," and the waste gas heat exchange channel into a single, compact, integrated phase change heat storage reactor. This structural integration is not a simple superposition but is based on a profound understanding of the thermodynamic processes at two different temperature levels. It deeply integrates the heat storage / release function of phase change materials with the heat exchange and chemical reaction functions of fluids in physical space, significantly reducing equipment volume and pipeline connections.

[0048] Second, this application features a dual-stage phase change material synergistic configuration based on temperature gradients. In existing technologies, even when phase change thermal storage is used, it is mostly a single melting point material. However, this application specifically and specifically configures a low-temperature phase change material with a melting point range of 90-130℃ and a high-temperature phase change material with a melting point range of 220-260℃, and arranges them respectively in the evaporation zone and the reaction zone. This "temperature-function" matching configuration precisely corresponds to the thermodynamic requirements of the methanol reforming process from liquid to gas and then to chemical reaction, realizing the "step-by-step" capture and utilization of heat from high-temperature exhaust gas, rather than simple heat storage. This reflects the idea of ​​refined management of energy quality.

[0049] Third, this application features a synergistic buffering characteristic of a two-stage thermal storage module to cope with dynamic thermal shocks. Existing technologies typically rely on a single thermal inertia or a simple control valve when dealing with exhaust gas fluctuations; however, this application utilizes the "cascade" effect of two-stage phase change thermal storage modules to buffer thermal shocks. When high-temperature exhaust gas first washes over the high-temperature reaction zone, the phase change material in that zone absorbs the peak heat to prevent overheating. When the exhaust gas enters the low-temperature evaporation zone after cooling, the material in that zone absorbs the remaining heat. Conversely, when the exhaust gas heat is insufficient, the phase change material in the high-temperature zone first releases latent heat to preferentially maintain the temperature of the reaction zone, while the material in the low-temperature zone subsequently releases latent heat to ensure stable vaporization of methanol. This multi-stage synergistic buffering mechanism, which releases heat from high to low along the exhaust gas flow direction on demand, cannot be achieved by a single thermal storage module.

[0050] Fourth, this application adopts a specific structure of counter-current heat exchange and zoned heating between the exhaust gas path and the process flow path. In the specific implementation, the exhaust gas (hot fluid) first passes through the high-temperature reaction zone and then through the low-temperature evaporation zone, while the process fluid (methanol / water) first evaporates in the low-temperature zone and then enters the high-temperature zone for reaction. This "counter-current" layout of the hot fluid and the process fluid, combined with the specific structures such as heat exchange fins, baffles, and vaporization heat exchange pipes in the attached drawings, maximizes the heat exchange temperature difference and efficiency, which is a key technical feature that distinguishes it from conventional co-current or simple cross-flow heat exchange.

[0051] Compared with the prior art, the present invention has the following beneficial effects: 1. The present invention significantly improves energy utilization efficiency and realizes waste heat recovery in stages. By configuring a two-stage (low temperature stage and high temperature stage) phase change heat storage module, which corresponds to the two different temperature requirements of methanol vaporization and reforming reaction, the heat of engine exhaust gas is realized to achieve "temperature matching and staged utilization". The heat in the high temperature stage is used to drive the endothermic main reaction, and the heat in the low temperature stage is used for the preheating and vaporization of raw materials, avoiding the unreasonable downgrading of high-grade heat energy, thereby raising the thermal efficiency of the entire system to a new level.

[0052] 2. This invention possesses excellent resistance to operating condition fluctuations, ensuring stable hydrogen production. Utilizing a phase change material (PCM) with high latent heat as a heat buffer, it effectively isolates the drastic fluctuations in the temperature and flow rate of marine engine exhaust gas. When there is excess heat in the exhaust gas, the PCM melts to absorb and store heat; when there is insufficient heat, the PCM solidifies to release heat and replenish energy. This dual-stage heat storage design, especially the heat storage module in the high-temperature reaction zone, can stabilize the reforming reaction temperature within the narrow range most suitable for the catalyst (220-260℃), greatly improving the system's operational stability and the continuity of hydrogen production under varying ship load conditions. It avoids the problems of catalyst deactivation and sudden drops in hydrogen production rate caused by temperature fluctuations in traditional solutions.

[0053] 3. This invention employs a highly compact integrated design, saving ship space by combining the separate exhaust gas heat exchanger, phase change energy storage unit, methanol evaporator, and reforming reactor of traditional solutions into a compact, integrated phase change thermal energy storage reactor. This design significantly reduces the connecting pipelines and insulation structures between devices, substantially reducing the volume and weight of the entire hydrogen production system, enabling it to meet the stringent requirements of space-constrained environments such as ship engine rooms, and improving the system's engineering feasibility.

[0054] 4. This invention achieves flexible thermal energy management and distribution. Through the synergistic effect of the integrated reactor's internal structure (such as baffles and fins) and external bypass control valves, it can both enhance local heat transfer at the microscopic level and regulate the total heat entering the system at the macroscopic level. In particular, by prioritizing the consumption of the latent heat of the phase change material, it achieves proactive management of thermal energy supply, reducing energy waste caused by directly cutting off or bypassing high-temperature exhaust gas through valves. (See attached figures)

[0055] Figure 1 This is a schematic diagram of the system described in this invention;

[0056] Figure 2 This is a schematic diagram of the integrated phase change thermal energy storage reactor described in this invention.

[0057] Figure 3 This is a perspective view of the integrated phase change thermal energy storage reactor described in this invention;

[0058] Figure 4 This is a front view of the integrated phase change thermal energy storage reactor described in this invention;

[0059] Figure 5 This is a left view of the integrated phase change thermal energy storage reactor described in this invention;

[0060] Figure 6 This is the invention described Figure 4 Schematic diagram of the cross-sectional structure of the AA surface in the middle;

[0061] Figure 7 This is the invention described Figure 4 Schematic diagram of the cross-sectional structure of the BB surface;

[0062] Figure 8 This is a top view of the integrated phase change thermal energy storage reactor described in this invention;

[0063] Figure 9 This is a top view of the integrated phase change thermal energy storage reactor of the present invention after the top hole plate of the evaporation zone has been cut open;

[0064] Figure 10 This is a flowchart of the method described in this invention;

[0065] In the diagram: 1. Methanol storage tank; 2. Water storage tank; 3. Mixer; 4. Integrated phase change thermal storage reactor; 5. Condensation recovery device; 6. Reformer gas storage tank; 7. Engine; 8. Bypass control valve; 41. Top hole plate of evaporation zone; 42. Low-temperature phase change material filling zone; 43. Methanol / water mixture inlet; 44. Vaporization heat exchange pipe; 45. Bottom hole plate of evaporation zone; 46. Medium-temperature exhaust gas passage; 47. Transition zone pipe; 48. Methanol steam inlet; 49. High-temperature exhaust gas heat exchange zone; 410. High-temperature phase change material filling zone; 411. Baffle; 412. Heat exchange fins; 413. Methanol reforming reaction pipe; 414. High-temperature exhaust gas inlet; 415. Reformer gas outlet; 416. Main shell. Detailed Implementation

[0066] The technical solution of the present invention will now be described in detail with reference to the accompanying drawings;

[0067] In this application, methanol steam reforming (MSR) is a catalytic chemical process in which methanol reacts with water vapor under endothermic conditions (typically 200-300°C) to produce hydrogen and carbon dioxide (CH3OH + H2O → CO2 + 3H2). This is the core chemical reaction of this invention and the technical basis for realizing in-situ hydrogen production on ships and converting waste heat from exhaust gas into hydrogen chemical energy. Its stable operation depends on precise temperature control, which is the core problem that this invention aims to solve.

[0068] In this application, Phase Change Material Thermal Energy Storage (PCM-TES) is a technology that utilizes the property of phase change materials (PCMs) to absorb or release a large amount of latent heat during physical state changes (such as solid-liquid) to store and release thermal energy. It is the key technical means of this invention. By using two PCMs with different melting points, it acts as a "thermal buffer" to absorb or release heat when the exhaust gas heat fluctuates, ensuring the temperature stability of the evaporation and reaction processes, and is the core of realizing the system's anti-disturbance capability.

[0069] In this application, cascade energy utilization is based on the temperature grade of the heat source and the temperature level of the heat demand. High-temperature heat sources are used for high-temperature demands, and medium-temperature heat sources are used for medium-temperature demands, achieving efficient utilization of heat energy from high to low, avoiding energy waste. This is the design concept and core advantage of this invention. It uses exhaust gas above 300°C for reforming reaction at 220-260°C, and then uses the cooled exhaust gas for raw material vaporization at 90-130°C, achieving "temperature matching and energy use according to quality", which significantly improves the overall thermal efficiency of the system.

[0070] In this application, temperature fluctuation suppression is achieved by reducing or eliminating the amplitude and rate of temperature changes at key points of the system (such as the reaction bed) caused by external heat source disturbances through specific thermal management strategies (such as introducing high heat capacity materials, phase change materials, or control algorithms). This is the core technical problem that this invention aims to solve. The variable load characteristics of marine engines are inherent, and MSR catalysts are extremely sensitive to temperature. All the innovative designs of this invention (two-stage PCM, counterflow, valve control) ultimately aim to effectively suppress temperature fluctuations in the reforming reaction zone, thereby ensuring a stable and efficient hydrogen yield.

[0071] refer to Figure 1 , Figure 2 , Figures 3 to 9The structure of a methanol vapor reforming system integrating marine exhaust gas drive and phase change thermal storage according to one or more embodiments of this application is shown. This system is applied in the field of marine power, and in particular, it is used to drive a methanol vapor reforming reaction using the waste heat of engine (7) exhaust gas to achieve in-situ stable hydrogen production. The system includes: a methanol storage tank (1), a water storage tank (2), a mixer (3), an integrated phase change thermal storage reactor (4), a condensate recovery device (5), a reformed gas storage tank (6), and a bypass control valve (8).

[0072] When one or more embodiments are executed, the integrated phase change thermal storage reactor (4) is the core device for realizing the present invention, which is configured to integrate four major functions: tail gas heat exchange, phase change thermal storage, methanol vaporization, and reforming reaction. Figure 2 As shown, the reactor (4) includes a main shell (416) and a low-temperature phase change thermal storage evaporation zone and a high-temperature phase change thermal storage reaction zone defined therein.

[0073] In some cases, the specific structure of the low-temperature phase change thermal storage evaporation zone is as follows:

[0074] It includes a low-temperature phase change material filling area (42), a vaporization heat exchange pipe (44), and a medium-temperature exhaust gas passage (46) formed inside the main body shell (416). The low-temperature phase change material filling area (42) is filled with a first phase change material with a melting point range of 90-130°C, preferably 90-120°C. The filling area (42) is formed between the inner wall of the main body shell (416) and the outer wall of the vaporization heat exchange pipe (44).

[0075] The inlet of the vaporization heat exchange pipe (44) is connected to the mixer (3) for receiving a liquid methanol / water mixture.

[0076] The medium-temperature exhaust gas passage (46) is formed between the inner wall of the main shell (416) and the low-temperature phase change material filling area (42), and is located around the vaporization heat exchange pipe (44) to guide the medium-temperature exhaust gas to flow through and exchange heat with the low-temperature phase change material filling area (42) and the vaporization heat exchange pipe (44).

[0077] In some cases, the specific structure of the high-temperature phase change thermal storage reaction zone is as follows:

[0078] It includes a high-temperature phase change material filling zone (410), a methanol reforming reaction pipeline (413), and a high-temperature tail gas heat exchange zone (49) formed inside the main body shell (416). The high-temperature phase change material filling zone (410) is filled with a second phase change material with a melting point range of 220-260°C, preferably 220-260°C. The filling zone (410) is formed between the inner wall of the main body shell (416) and the outer wall of the methanol reforming reaction pipeline (413).

[0079] The methanol reforming reaction pipeline (413) is equipped with a methanol steam reforming catalyst, and its inlet is connected to the outlet of the vaporization heat exchange pipeline (44) through the transition zone pipeline (47). The high-temperature tail gas heat exchange zone (49) is formed between the inner wall of the main shell (416) and the high-temperature phase change material filling zone (410), and is connected to the exhaust gas channel.

[0080] like Figure 6 As shown, the heat exchange zone (49) is provided with one or more baffles (411) and / or heat exchange fins (412) to increase airflow disturbance and enhance heat exchange between the exhaust gas and the high-temperature phase change material filling zone (410).

[0081] In some cases, the flow paths of the exhaust gas passage and the working fluid are as follows: Figure 2 As shown, the exhaust gas passage passes sequentially through the high-temperature phase change thermal storage reaction zone and the low-temperature phase change thermal storage evaporation zone.

[0082] Specifically, the exhaust gas from the engine (7) is regulated by the bypass control valve (8) and enters the reactor (4) from the high-temperature exhaust gas inlet (414). It first flows through the high-temperature exhaust gas heat exchange zone (49) and exchanges heat with the high-temperature phase change material filling zone (410). After releasing some heat, the medium-temperature exhaust gas passes through the medium-temperature exhaust gas channel (46) and through the bottom hole plate (45) of the evaporation zone, and enters the low-temperature phase change heat storage evaporation zone, where it exchanges heat with the low-temperature phase change material filling zone (42) and the vaporization heat exchange pipe (44). Finally, the low-temperature exhaust gas is discharged from the top hole plate (41) of the evaporation zone.

[0083] The flow path of the methanol / water mixture (process fluid) is the opposite. The mixture enters the vaporization heat exchange pipe (44) from the methanol / water mixture inlet (43) and absorbs heat in the low temperature zone to vaporize into steam. Subsequently, the methanol / water vapor enters the methanol reforming reaction pipe (413) from the methanol water vapor inlet (48) through the transition zone pipe (47) and undergoes catalytic reforming reaction in the high temperature zone. The generated hydrogen-rich reforming gas flows out from the reforming gas outlet (415).

[0084] In some embodiments, the system also has two operating modes to cope with exhaust gas fluctuations:

[0085] When the exhaust gas temperature or flow rate of the engine (7) is higher than the rated value, the system is in the first working mode, and the bypass control valve (8) is opened to the first degree (such as fully open), so that all or part of the exhaust gas enters the reactor (4). The phase change materials in the high temperature phase change material filling area (410) and the low temperature phase change material filling area (42) absorb excess heat and melt, and store thermal energy.

[0086] When the exhaust gas temperature or flow rate of the engine (7) is lower than the rated value, the system is in the second working mode, and the bypass control valve (8) is adjusted to the second opening degree (such as reducing the opening degree or closing). At this time, the phase change material in the two filling zones releases latent heat to maintain the temperature stability of the methanol vapor reforming reaction and the methanol / water mixture vaporization process.

[0087] Through the integrated structural design and the synergistic effect of the two-stage phase change thermal storage materials, this system effectively suppresses temperature fluctuations while realizing the cascade utilization of waste gas heat, significantly improving the system's compactness and operational stability.

[0088] refer to Figure 10 The diagram illustrates a flowchart of a methanol steam reforming method integrating marine exhaust gas drive and phase change thermal storage according to one or more embodiments of this application. This method, based on the aforementioned system, is used to stably and efficiently produce hydrogen under varying operating conditions of a marine engine, and includes the following steps.

[0089] Step (a), preparation of methanol / water mixture:

[0090] In this step, the mixer (3) is configured to perform a mixing operation. Specifically, the mixer (3) receives liquid methanol and deionized water from the methanol storage tank (1) and the water storage tank (2) respectively, and mixes them thoroughly in a preset ratio (e.g., a molar ratio of 1:1 to 1:1.5) to form a homogeneous methanol / water mixture.

[0091] Step (b), vaporization of the mixture:

[0092] In this step, the low-temperature phase change thermal storage evaporation zone of the integrated phase change thermal storage reactor (4) is configured to perform a vaporization operation.

[0093] Specifically, the methanol / water mixture generated in step (a) is introduced into the vaporization heat exchange pipe (44). At the same time, the engine's medium-temperature exhaust gas (temperature range of about 130-200°C) flowing through the medium-temperature exhaust gas passage (46) heats the low-temperature phase change material filling area (42) and the vaporization heat exchange pipe (44), heating the mixture to above its boiling point and converting it into methanol / water vapor.

[0094] During this process, if the exhaust gas is not heated evenly or the temperature drops, the first phase change material (melting point 90-130℃) in the low-temperature phase change material filling area (42) will solidify and release latent heat, which will give priority to meeting the heat required for vaporization.

[0095] Step (c), methanol steam reforming reaction:

[0096] In this step, the high-temperature phase change thermal storage reaction zone of the integrated phase change thermal storage reactor (4) is configured to perform reforming reaction operations.

[0097] Specifically, the methanol / water vapor generated in step (b) is introduced into the methanol reforming reaction pipeline (413) via the transition zone pipeline (47) and comes into contact with the reforming catalyst filled therein. At the same time, the high-temperature exhaust gas (typically ≥300°C) flowing through the high-temperature exhaust gas heat exchange zone (49) heats the high-temperature phase change material filling zone (410), providing heat for the endothermic reaction.

[0098] At a reaction temperature of 220-260℃, the reaction CH3OH + H2O → CO2 + 3H2 occurs, generating hydrogen-rich reformed gas. When the tail gas temperature fluctuates, the second phase change material (melting point 220-260℃) in the high-temperature phase change material filling zone (410) suppresses the temperature fluctuation of the reaction zone through the phase change process (melting endothermic or solidification exothermic), ensuring that the catalyst works within a stable temperature window.

[0099] Step (d) Dynamic adjustment of exhaust gas flow:

[0100] This step is performed in parallel with steps (b) and (c). The bypass control valve (8) is configured to perform flow regulation operation.

[0101] Specifically, the exhaust gas flow rate entering the integrated phase change thermal storage reactor (4) is adjusted in real time based on the load signal of the engine (7) or the feedback from the exhaust gas temperature sensor. When the exhaust gas heat fluctuates, the system prioritizes consuming the latent heat of the first and second phase change materials to stabilize the temperature, while the bypass control valve (8) serves as a macroscopic adjustment means to avoid energy waste or sudden changes in reaction temperature due to excessive valve adjustment.

[0102] Step (e), reformed gas condensation and storage:

[0103] In this step, the condensate recovery device (5) and the reformate storage tank (6) are configured to perform post-processing operations.

[0104] Specifically, the hydrogen-rich reformate (containing H2, CO2, and unreacted CH3OH and H2O) generated in step (d) is passed into a condensation recovery unit (5). This unit cools (e.g., to room temperature) to condense the unreacted gaseous methanol and water into liquid and separates and recovers them. The purified hydrogen-rich reformate (mainly containing H2 and CO2) is temporarily stored in a reformate storage tank (6) for use in an engine (7) or other hydrogen-using equipment.

[0105] In some cases, through the synergistic operation of steps (a) to (e) above, especially the "cascaded" thermal buffering effect of the two-stage phase change thermal storage modules in steps (b) and (c), combined with the macroscopic flow regulation in step (d), this method achieves the cascaded utilization of engine exhaust heat and precise and stable control of the reforming reaction temperature.

[0106] Specifically, the heat from the exhaust gas is first used to drive a high-temperature reforming reaction (for high-grade applications), and then used to preheat and vaporize the feedstock (for low-grade applications). When the exhaust gas fluctuates, the heat transfer path is: exhaust gas -> phase change material -> reaction / vaporization. The phase change material, as the primary "thermal stabilizer," significantly improves the system's hydrogen production stability and energy utilization efficiency under dynamic ship operating conditions.

[0107] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, the phrase "comprising an element defined as..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0108] The above technical solutions only embody the preferred technical solutions of the present invention. Any modifications that may be made by those skilled in the art to certain parts thereof embody the principles of the present invention and fall within the protection scope of the present invention.

Claims

1. A methanol steam reforming system integrating marine exhaust gas drive and phase change thermal storage, characterized in that, include: The integrated phase change thermal energy storage reactor (4) further includes: The low-temperature phase change thermal storage evaporation zone is filled with a first phase change material, the melting point of which is 90-130°C. The low-temperature phase change thermal storage evaporation zone is configured to receive a liquid methanol / water mixture and use the heat of the waste gas to heat and vaporize it into methanol / water vapor. The high-temperature phase change thermal storage reaction zone is filled with a second phase change material, the melting point of which is 220-260°C. The high-temperature phase change thermal storage reaction zone is in fluid communication with the low-temperature phase change thermal storage evaporation zone and is configured to receive methanol / water vapor from the low-temperature phase change thermal storage evaporation zone and contain a reforming catalyst to carry out methanol vapor reforming reaction to generate hydrogen-rich reformed gas. The exhaust gas passage passes sequentially through the high-temperature phase change heat storage reaction zone and the low-temperature phase change heat storage evaporation zone, and is used to guide the engine exhaust gas to first flow through the high-temperature phase change heat storage reaction zone to exchange heat with it, and then flow through the low-temperature phase change heat storage evaporation zone to exchange heat with it. A methanol storage tank (1) and a water storage tank (2) are used to store methanol and water, respectively; The mixer (3) is connected to the methanol storage tank (1) and the water storage tank (2) respectively, and is connected to the inlet of the low-temperature phase change thermal storage evaporation zone of the integrated phase change thermal storage reactor (4) for mixing methanol and water and supplying them to the integrated phase change thermal storage reactor (4). A bypass control valve (8) is installed on the exhaust gas pipeline between the engine (7) and the integrated phase change thermal storage reactor (4) to regulate the exhaust gas flow rate entering the integrated phase change thermal storage reactor (4).

2. The system according to claim 1, characterized in that, The integrated phase change thermal storage reactor (4) also includes: Main body shell (416); The methanol reforming reaction pipeline (413) is installed in the high-temperature phase change thermal storage reaction zone, and the reforming catalyst is installed in the methanol reforming reaction pipeline (413). A vaporization heat exchange pipe (44) is installed in the low-temperature phase change heat storage evaporation zone. The inlet of the vaporization heat exchange pipe (44) is connected to the mixer (3), and the outlet is connected to the inlet of the methanol reforming reaction pipe (413).

3. The system according to claim 2, characterized in that, The high-temperature phase change thermal storage reaction zone also includes: A high-temperature phase change material filling region (410) formed between the main body shell (416) and the methanol reforming reaction pipeline (413) is used to fill the second phase change material; A high-temperature exhaust gas heat exchange zone (49) is formed between the inner wall of the main body shell (416) and the high-temperature phase change material filling area (410). The high-temperature exhaust gas heat exchange zone (49) is connected to the exhaust gas channel and is provided with one or more baffles (411) and / or heat exchange fins (412) to enhance the heat exchange between the exhaust gas and the high-temperature phase change material filling area (410).

4. The system according to claim 2, characterized in that, The low-temperature phase change thermal storage evaporation zone also includes: A low-temperature phase change material filling region (42) is formed between the main body shell (416) and the vaporization heat exchange pipe (44) for filling the first phase change material; A medium-temperature exhaust gas channel (46) is formed between the inner wall of the main shell (416) and the low-temperature phase change material filling area (42). The medium-temperature exhaust gas channel (46) is connected to the exhaust gas channel and is located around the vaporization heat exchange pipe (44).

5. The system according to claim 1, characterized in that, The system also includes a condensation recovery device (5) and a reforming gas storage tank (6). The inlet of the condensation recovery device (5) is connected to the reforming gas outlet (415) of the integrated phase change thermal reactor (4), and its outlet is connected to the reforming gas storage tank (6) for cooling and separating unreacted methanol and water in the reforming gas.

6. The methanol steam reforming system and method integrating marine exhaust gas drive and phase change thermal storage according to claim 1, characterized in that, The system has a first working mode and a second working mode; In the first working mode, when the exhaust gas temperature or flow rate of the engine (7) is higher than the rated value, the bypass control valve (8) is opened to the first opening degree, so that part or all of the exhaust gas enters the integrated phase change heat storage reactor (4). The phase change materials in the high temperature phase change heat storage reaction zone and the low temperature phase change heat storage evaporation zone absorb excess heat and melt to store thermal energy. In the second working mode, when the exhaust gas temperature or flow rate of the engine (7) is lower than the rated value, the bypass control valve (8) is adjusted to the second opening degree, and the phase change materials in the high temperature phase change heat storage reaction zone and the low temperature phase change heat storage evaporation zone release latent heat to maintain the temperature stability of the methanol vapor reforming reaction and the vaporization process of the methanol / water mixture.

7. The system according to claim 1, characterized in that, The melting point range of the first phase change material is preferably 90-120℃, and the melting point range of the second phase change material is preferably 220-260℃.

8. A method for methanol vapor reforming driven by marine exhaust gas and integrating phase change thermal storage, said method being implemented based on the system of any one of claims 1 to 7, characterized in that, Includes the following steps: (a) Methanol and water from the methanol storage tank (1) and the water storage tank (2) are mixed by the mixer (3) to form a methanol / water mixture; (b) The methanol / water mixture is introduced into the low-temperature phase change heat storage evaporation zone of the integrated phase change heat storage reactor (4), and the mixture is heated and vaporized into methanol / water vapor by the engine exhaust gas flowing through the zone and the latent heat released by the first phase change material. (c) The methanol / water vapor is introduced into the high-temperature phase change heat storage reaction zone of the integrated phase change heat storage reactor (4). Under the action of the reforming catalyst, and by utilizing the latent heat released by the engine exhaust gas flowing through the zone and the second phase change material, an endothermic reforming reaction is carried out to generate hydrogen-rich reformed gas. (d) The flow rate of the tail gas entering the integrated phase change thermal storage reactor (4) is controlled by the bypass control valve (8). When the tail gas heat fluctuates, the latent heat of the first phase change material and the second phase change material is used first to stabilize the reaction temperature.

9. The method according to claim 8, characterized in that, In steps (b) and (c), the engine exhaust gas flows sequentially through the high-temperature phase change heat storage reaction zone and the low-temperature phase change heat storage evaporation zone, thereby realizing the cascade utilization of heat.

10. The method according to claim 8, characterized in that, It also includes step (e): passing the hydrogen-rich reformed gas into a condensation recovery device (5) to separate and recover unreacted methanol and water therein, and then storing the purified reformed gas in a reformed gas storage tank (6).

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