Ammonia-methanol coupling gas production device and use method thereof

Abstract

The invention discloses an ammonia-methanol coupling gas production device and a use method thereof, and belongs to the technical field of controllable atmosphere preparation, the ammonia-methanol coupling gas production device comprises a central combustion zone, a peripheral cracking zone and a tail mixing purification zone which are coaxially nested; the central combustion area comprises a hearth wall, and the hearth wall is of a honeycomb-shaped porous heat exchange structure; the peripheral cracking area is arranged on the outer side of the central combustion area, a catalyst bed layer of a spiral flow guide structure is arranged in the peripheral cracking area, and a high-temperature-resistant heat-conducting filling layer is arranged between the catalyst bed layer and the hearth wall of the central combustion area; the tail mixing and purifying area is connected to the downstream of the central combustion area and the peripheral cracking area and used for mixing and purifying combustion products from the central combustion area and cracking gas from the peripheral cracking area. By optimizing a heat exchange interface and a catalyst bed layer structure, the heat transfer uniformity and the response speed are enhanced, so that stable temperature control and preparation of high-purity mixed gas are realized.

Description

Technical Field

[0001] This invention relates to the field of controlled atmosphere preparation technology, specifically to an ammonia-methanol coupled gas generation device and its usage method. Background Technology

[0002] Ammonia-methanol co-generation is a process that utilizes the heat released from ammonia combustion to drive methanol cracking, thereby producing a mixture of nitrogen, carbon monoxide, and hydrogen. However, existing ammonia-methanol co-generation equipment and processes have certain problems: Existing equipment often employs flat-plate or simple sleeve-type heat exchange structures between the central combustion zone and the peripheral cracking zone. This results in a contact gap between the furnace wall and the catalyst bed, leading to high contact thermal resistance and making it difficult to efficiently transfer the heat generated by ammonia combustion to the methanol cracking zone. Furthermore, the traditional heat exchange structure has a limited heat exchange area, resulting in uneven heat distribution. Some areas experience localized overheating, while others suffer from insufficient heat supply. This not only reduces the methanol cracking rate but also leads to unstable mixed gas production. The ammonia combustion temperature in the central combustion zone of existing equipment is typically as high as 850~900℃, while the optimal temperature range for methanol cracking is 270~280℃. The temperature difference between the two is significant. However, existing equipment lacks an effective heat decay and temperature control mechanism, and only regulates the temperature through a single cooling jacket. This cannot respond quickly to temperature fluctuations, causing the temperature in the cracking zone to easily exceed the optimal range. Furthermore, temperature fluctuations accelerate the sintering and loss of active components in traditional Cu-Zn-Al catalysts, shortening catalyst lifespan and increasing equipment maintenance costs and downtime. Summary of the Invention

[0003] To address the problems existing in the prior art, this invention provides an ammonia-methanol coupled gasification device and its usage method. By optimizing the heat exchange interface and catalyst bed structure, the uniformity of heat transfer and the response speed are enhanced, thereby achieving stable temperature control and the preparation of high-purity mixed gas, meeting the stringent requirements of high-carbon steel heat treatment for atmosphere composition and stability.

[0004] The technical solution of the present invention is as follows: In a first aspect of the invention, an ammonia-methanol coupled gasification device is provided, comprising a central combustion zone, a peripheral pyrolysis zone, and a tail mixing and purification zone coaxially nested; the central combustion zone includes a furnace wall configured with a honeycomb porous heat exchange structure; the peripheral pyrolysis zone is disposed outside the central combustion zone, and the interior of the peripheral pyrolysis zone is provided with a catalyst bed having a spiral flow guiding structure, and a high-temperature resistant thermally conductive filling layer is disposed between the catalyst bed and the furnace wall of the central combustion zone; the tail mixing and purification zone is connected downstream of the central combustion zone and the peripheral pyrolysis zone, and is used to mix and purify the combustion products from the central combustion zone and the pyrolysis gas from the peripheral pyrolysis zone. In some embodiments of the present invention, the honeycomb porous heat exchange structure is made of silicon nitride ceramic, and the honeycomb porous heat exchange structure includes a plurality of axially distributed axial channels along the furnace wall, wherein the diameter of the axial channels is set between 2 and 5 mm. In some embodiments of the present invention, the catalyst bed contains catalyst particles, and the pitch of the spiral flow guiding structure is set to 3 to 5 times the diameter of the catalyst particles. In some embodiments of the present invention, the high-temperature resistant thermally conductive filling layer is a silicon nitride-based ceramic thermally conductive paste or a flexible graphite pad. In some embodiments of the present invention, the silicon nitride-based ceramic thermal paste is configured to have a thermal conductivity of not less than 8 W / m Kelvin and a volume shrinkage rate of not more than 0.5% when operating continuously at 800 degrees Celsius. In some embodiments of the present invention, the peripheral cracking zone further includes multiple temperature sensors disposed on the inner wall of the catalyst bed and a cooling jacket disposed outside the device. The multiple temperature sensors and the cooling jacket are communicatively connected to an external temperature control unit to form a closed-loop temperature control module. In some embodiments of the present invention, the plurality of temperature sensors are evenly distributed at predetermined intervals along the axial direction of the catalyst bed, the cooling jacket is configured as an annular structure, and the cooling jacket contains a cooling medium. In some embodiments of the present invention, the tail mixing and purification zone includes, in sequence along the airflow direction, a mixed gas guide cavity, a condenser, a molecular sieve dryer, a deoxygenation module, and a mixed gas outlet. In some embodiments of the present invention, the top of the central combustion zone is provided with an ammonia inlet and an air inlet, the ammonia inlet is provided with an igniter, and the top of the peripheral pyrolysis zone is provided with a methanol vapor inlet. In a second aspect of the invention, a method of using an ammonia-methanol coupled gasification apparatus is provided, comprising: Ammonia and air are introduced into the central combustion zone at a predetermined molar ratio for combustion, producing high-temperature flue gas. The vaporized methanol is fed into the spiral catalyst bed in the outer cracking zone for cracking reaction, while the cracking temperature is maintained within the set temperature range by the high-temperature resistant thermally conductive filling layer and the closed-loop temperature control module. The high-temperature flue gas from the central combustion zone is mixed with the pyrolysis gas from the peripheral pyrolysis zone in the tail mixing and purification zone, and then condensed, dried and deoxygenated in sequence to obtain a mixed gas.

[0005] One or more technical solutions of the present invention have the following beneficial effects: By setting the central combustion zone as a honeycomb porous heat exchange structure, its dense channels greatly increase the effective heat exchange area, making heat transfer more uniform and sufficient. Combined with the high-temperature resistant thermally conductive filling layer set between the furnace wall and the catalyst bed in the outer cracking zone, the contact gap in the traditional structure is effectively eliminated, and the interfacial thermal resistance is greatly reduced. The two work together to ensure that the heat released by ammonia combustion can be efficiently and stably transferred to the methanol cracking zone, fundamentally solving the problems of insufficient heat transfer and uneven distribution.

[0006] The spiral-guided catalyst bed structure in the peripheral pyrolysis zone optimizes the reaction gas flow field and promotes uniform temperature distribution. Simultaneously, a closed-loop temperature control module, integrated with the temperature sensor in the catalyst bed and comprising an external cooling jacket and temperature control unit, can monitor and dynamically adjust the temperature of the peripheral pyrolysis zone in real time, responding quickly to heat fluctuations and precisely maintaining the pyrolysis reaction temperature within the optimal range. This effectively prevents sintering and loss of active components due to temperature fluctuations, significantly extends catalyst lifespan, and ensures the long-term stability of the unit.

[0007] This invention not only significantly improves the overall heat exchange efficiency and thermal energy utilization of the system, but also ensures the high efficiency and stability of the methanol cracking reaction, thereby enabling the continuous production of a mixed gas with uniform composition and high purity, which fully meets the stringent requirements of the protective atmosphere for the precision heat treatment of high carbon steel. Attached Figure Description

[0008] Figure 1 This is an internal cross-sectional view of an ammonia-methanol coupled gasification device provided in Embodiment 1 of the present invention; Figure 2 The present invention provided in Embodiment 1 Figure 1 AA section view in the image.

[0009] In the diagram: 1. Central combustion zone; 11. Furnace wall; 111. Axial channel; 12. Ammonia inlet; 13. Air inlet; 14. Ignition device; 2. Peripheral cracking zone; 21. Catalyst bed; 211. Catalyst particles; 22. High-temperature resistant thermally conductive filling layer; 23. Temperature sensor; 24. Cooling jacket; 25. Methanol vapor inlet; 3. Tail-end mixing and purification zone; 31. Mixed gas guide chamber; 32. Condenser; 33. Molecular sieve dryer; 34. Deoxygenation module; 35. Mixed gas outlet; 4. Temperature control unit. Detailed Implementation

[0010] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0011] Example 1 In a typical embodiment of the present invention, such as Figure 1 As shown, an ammonia-methanol coupled gasification device is proposed, comprising a central combustion zone 1, an outer pyrolysis zone 2, and a tail mixing and purification zone 3 arranged coaxially. The central combustion zone 1 includes a furnace wall 11, which is configured as a honeycomb porous heat exchange structure. The outer pyrolysis zone 2 is located outside the central combustion zone 1, and the interior of the outer pyrolysis zone 2 is provided with a catalyst bed 21 with a spiral flow guiding structure. A high-temperature resistant thermally conductive filling layer 22 is provided between the catalyst bed 21 and the furnace wall 11 of the central combustion zone 1. The tail mixing and purification zone 3 is connected downstream of the central combustion zone 1 and the outer pyrolysis zone 2, and is used to mix and purify the combustion products from the central combustion zone 1 and the pyrolysis gas from the outer pyrolysis zone 2. The overall configuration of the central combustion zone 1, the outer pyrolysis zone 2, and the tail mixing and purification zone 3, arranged coaxially, achieves a compact process flow and efficient space utilization. The central combustion zone 1, acting as an internal heat source, generates heat that can be radially transferred to the outer pyrolysis zone 2. This inside-out heat transfer path is the shortest, reducing ineffective heat dissipation along the transfer path. The honeycomb porous heat exchange structure on the furnace wall 11 of the central combustion zone 1 transforms the traditional solid or smooth wall surface into a three-dimensional interface with numerous micro-channels, greatly increasing the effective contact area between the furnace wall 11 and the internal high-temperature flue gas and the external environment, thereby significantly improving the heat exchange capacity per unit volume. Heat is conducted through the numerous porous wall surfaces, resulting in a more uniform heat flow distribution and helping to avoid localized hot or cold spots that might occur with traditional flat wall surfaces.

[0012] The peripheral pyrolysis zone 2 is located outside the central combustion zone 1 and employs a catalyst bed 21 with a spiral flow guiding structure. The spiral structure alters the flow path of the methanol vapor reaction gas, causing it to advance along the spiral channel, extending its residence time within the reaction zone, and promoting sufficient contact between the gas flow and the catalyst particles 211. The spiral flow channel can guide the gas flow to generate a certain degree of rotation or disturbance, which helps improve the uniformity of temperature distribution across the reactor cross-section and prevents gas flow short-circuiting or the formation of stagnant zones. A high-temperature resistant thermally conductive filling layer 22, with a thickness of 3-8 mm, is provided between the catalyst bed 21 and the furnace wall 11 of the central combustion zone 1. This filling layer solves the contact thermal resistance problem and establishes a continuous and highly thermally conductive physical connection by filling the assembly gap, ensuring that the high-temperature heat generated in the central combustion zone 1 can be efficiently and with low loss transferred across the interface to the catalyst bed 21 of the peripheral pyrolysis zone 2 that requires heat.

[0013] The tail mixing and purification zone 3 is connected downstream and is responsible for combining and purifying the products of the two reaction zones. This avoids the need for additional pipeline connections and mixing equipment, reduces system complexity and potential leakage points, and allows the high-temperature combustion flue gas and pyrolysis gas to mix in a timely manner, utilizing the waste heat of the flue gas and initiating the initial homogenization process.

[0014] The honeycomb porous heat exchange structure is made of silicon nitride ceramic. The honeycomb porous heat exchange structure includes several axially distributed axial channels 111 along the furnace wall 11. The diameter of the axial channels 111 is set between 2 and 5 mm. Under repeated thermal cycling conditions in the central combustion zone 1, where temperatures can reach hundreds of degrees Celsius, silicon nitride ceramics maintain structural integrity and dimensional stability, resisting creep, oxidation, or phase transformation. This ensures the long-term reliable operation of the heat exchange structure. Its thermal shock resistance allows the structure to withstand rapid temperature changes caused by combustion start-up, shutdown, or load variations, preventing cracking. Excellent thermal conductivity ensures that heat can quickly pass through the ceramic wall itself, and combined with the large surface area advantage of its porous structure, this further amplifies heat exchange efficiency.

[0015] The axially distributed channel design aligns the channel direction with the mainstream direction of the high-temperature flue gas and the radial direction of heat transfer outward, reducing flow resistance and providing an orderly path for heat conduction along the wall in both the axial and radial directions.

[0016] The setting of the aperture range in this embodiment is an optimized balance between increasing the heat exchange area, ensuring the mechanical strength of the structure, and controlling the pressure drop of gas flow. Too small an aperture may lead to blockage and a sharp increase in pressure drop, while too large an aperture will weaken the surface area gain effect.

[0017] The catalyst bed 21 contains catalyst particles 211, and the pitch of the spiral flow guiding structure is set to 3 to 5 times the diameter of the catalyst particles 211. When the pitch is three to five times the diameter of the catalyst particles 211, a stable bed of catalyst particles 211 can be formed within the helical flow guiding structure, while ensuring that the channels between adjacent helical turns are sufficiently wide to avoid particle blockage or obstructed airflow. An appropriate pitch allows the reactant gas to periodically experience expansion and convergence changes in the flow path as the helical structure advances, which helps to enhance convection and diffusion mass transfer between the gas and the surface of the catalyst particles 211, promoting a complete reaction. Simultaneously, this configuration also facilitates the transfer and dissipation of reaction heat, as the helical flow guiding structure provides a more regular heat exchange interface for the cooling medium or adjacent structures.

[0018] The high-temperature resistant thermally conductive filler layer 22 is made of silicon nitride-based ceramic thermal paste or flexible graphite pad.

[0019] With this setup, both silicon nitride-based ceramic thermal paste and flexible graphite pads can effectively reduce interfacial thermal resistance. The silicon nitride-based ceramic thermal paste is in paste form during application, which can flow and fill microscopic unevenness. After curing, it forms a dense ceramic layer with high chemical and physical compatibility with the adjacent silicon nitride ceramic furnace wall 11. This not only achieves close contact, but its thermal conductivity can also be adaptively designed to meet the high-temperature requirements of actual use, ensuring smooth heat conduction across the interface.

[0020] Flexible graphite gaskets utilize the inherent high thermal conductivity and anisotropy of graphite materials. The thermal conductivity of flexible graphite gaskets ranges from 100 to 150 W / (m²). Between the K and C surfaces, its soft and compressible properties allow it to deform under assembly pressure, perfectly fitting two potentially uneven metal or ceramic surfaces, thus eliminating any air gaps invisible to the naked eye. Air is a poor conductor of heat, so eliminating gaps eliminates the main source of thermal resistance.

[0021] Both materials are heat-resistant and adaptable to the high-temperature environment of the outer wall of the combustion zone, ensuring the stable performance of the filler layer under long-term use. They are the core material guarantee for achieving efficient and stable thermal bridge connection.

[0022] The silicon nitride-based ceramic thermal paste is formulated with a thermal conductivity of not less than 8 W / m Kelvin and a volume shrinkage rate of not more than 0.5% when operating continuously at 800 degrees Celsius. With this configuration, the thermal conductivity of the silicon nitride-based ceramic thermal paste can ensure the speed and efficiency of heat transfer during actual use, which makes the heat flow resistance from the furnace wall 11 to the catalyst bed 21 shell smaller and the response faster.

[0023] In high-temperature operating environments, many materials undergo sintering, volatilization, or phase transformation, leading to volume shrinkage. If the filler layer shrinks significantly, new gaps will be created between it and the side walls, reintroducing contact thermal resistance and causing heat transfer efficiency to decline over time. By controlling the volume shrinkage rate to no more than 0.5%, the cured thermal paste layer can maintain close contact with the wall surface after long-term high-temperature service, preserving its initial thermal conductivity. This ensures the long-term stability of the heat transfer efficiency and temperature control capability of the entire device, reducing maintenance needs due to material degradation.

[0024] The peripheral cracking zone 2 also includes multiple temperature sensors 23 disposed on the inner wall of the catalyst bed 21 and a cooling jacket 24 disposed outside the device. The multiple temperature sensors 23 and the cooling jacket 24 together with the external temperature control unit 4 form a closed-loop temperature control module.

[0025] This setup enables real-time, in-situ monitoring and active control of the reaction temperature in the peripheral pyrolysis zone 2. Multiple temperature sensors 23 can acquire temperature information at different axial or circumferential positions within the catalyst bed 21, providing a more representative representation of the entire reaction zone's temperature state than a single measuring point, thus avoiding control deviations caused by a single measurement location. Connecting the signals from the temperature sensors 23 to the actuator of the cooling jacket 24 in a closed loop with the temperature control unit 4 forms a closed-loop temperature control module. This means that the flow rate or temperature of the cooling medium can be automatically and promptly adjusted based on the deviation between the measured temperature and the target temperature, thereby dynamically removing excess heat and achieving precise control of the pyrolysis temperature. It can also quickly respond to temperature disturbances caused by changes in combustion conditions.

[0026] Multiple temperature sensors 23 are evenly distributed at predetermined intervals along the axial direction of the catalyst bed 21. The cooling jacket 24 is configured as a ring structure and contains a cooling medium. Multiple temperature sensors 23 are evenly distributed along the axial direction to obtain the axial temperature distribution, enabling the closed-loop temperature control module to make decisions based on more comprehensive information. The cooling jacket 24 is configured as a ring structure and contains a built-in cooling medium, providing a uniform cooling interface surrounding the outer perimeter of the cracking zone 2. The ring structure ensures the uniformity of cooling in the circumferential direction, avoiding local overcooling or undercooling. The cooling medium circulates within the jacket, continuously carrying away the heat conducted from the catalyst bed 21 shell. Through direct surrounding cooling, a dynamic balance is formed with the radial heating from the central combustion zone 1. By adjusting the cooling intensity, the temperature level of the entire outer perimeter cracking zone 2 is effectively and uniformly controlled, precisely stabilizing it within the narrow temperature window required for efficient methanol cracking, effectively preventing catalyst deactivation due to overheating or large temperature fluctuations.

[0027] The tail mixing and purification zone 3 includes, in sequence along the airflow direction, a mixed gas guide cavity 31, a condenser 32, a molecular sieve dryer 33, a deoxygenation module 34, and a mixed gas outlet 35. The mixed gas guide cavity 31 first provides a buffer and preliminary mixing space for the two gas streams, making the gas composition tend to be homogeneous. Then it enters the condenser 32, where the temperature difference condenses most of the water vapor in the high-temperature mixed gas into liquid water and removes it. After being condensed and cooled and having most of the moisture removed, the gas then enters the molecular sieve dryer 33. The molecular sieve dryer 33 can deeply adsorb the trace amounts of residual moisture in the gas, meeting the stringent requirements for atmosphere dryness in precision heat treatment. The deoxidation module 34 is specifically designed to remove any trace amounts of oxygen that may be present through catalytic or chemical adsorption, completely eliminating impurities that cause workpiece oxidation, and finally producing a high-purity mixed gas that is output from the outlet.

[0028] The top of the central combustion zone 1 is provided with an ammonia inlet 12 and an air inlet 13. An igniter 14 is provided at the ammonia inlet 12. The top of the outer cracking zone 2 is provided with a methanol vapor inlet 25.

[0029] This configuration facilitates a top-to-bottom airflow, aligning with the direction of combustion product emissions and ensuring smooth flow. The top-mounted igniter 14 ensures safe and reliable ignition of the mixture, while the methanol vapor inlet 25 is positioned at the top of the peripheral cracking zone 2, allowing methanol vapor to flow downwards through the spiral catalyst bed 21. This flow direction fully utilizes gravity, aiding in vapor distribution and matching the reaction process within the catalyst bed 21.

[0030] By coordinating the above settings with the coaxial nested overall structure, a clear and orderly material flow path is formed. That is, fuel and combustion air enter the central reaction from the top, and endothermic reactants enter the peripheral reaction from the top. The products of both reactions flow downward to the tail end to converge and be purified, thus achieving a reasonable reaction.

[0031] In a second aspect of the invention, a method of using an ammonia-methanol coupled gasification apparatus is provided, comprising: Ammonia and air are introduced into the central combustion zone 1 at a predetermined molar ratio for combustion, producing high-temperature flue gas. The vaporized methanol is fed into the spiral catalyst bed 21 of the outer cracking zone 2 for cracking reaction, and the cracking temperature is maintained within the set temperature range by the high temperature resistant thermally conductive filling layer 22 and the closed-loop temperature control module. The high-temperature flue gas from the central combustion zone 1 is mixed with the pyrolysis gas from the peripheral pyrolysis zone 2 in the tail mixing and purification zone 3, and then condensed, dried and deoxygenated in sequence to obtain a mixed gas.

[0032] Specifically, during the ammonia combustion process, ammonia and air undergo oxygen-deficient combustion in the central combustion zone 1 at a molar ratio of 1-1.2, with the combustion temperature maintained at 850-900℃. The combustion products are high-temperature N2 and water vapor, and the released heat is transferred to the outer pyrolysis zone 2 through the honeycomb porous furnace wall 11 and the high-temperature resistant thermally conductive filling layer 22.

[0033] During the methanol cracking process, liquid methanol is vaporized and then introduced into the spiral catalyst bed 21 at a flow rate of 0.1-0.3 m / s. The cracking reaction occurs under the action of Cu-Zn-Al catalyst. Through the heat attenuation of the honeycomb porous structure, the fluidized heat dissipation of the spiral channel, and the dynamic adjustment of the closed-loop temperature control module, the cracking temperature is precisely controlled at 270~280℃ to ensure that the methanol cracking rate is ≥98%. During the mixing and purification process, the combustion products and the cracked gas are fully mixed in the tail mixing and purification zone 3. After condensation and dehydration, molecular sieve drying and deoxygenation treatment, N2-CO-H2 ternary mixed gas is obtained, in which N2 accounts for 60%~80%, CO accounts for 5%~15%, H2 accounts for 10%~30%, and the heat exchange efficiency is ≥85%.

[0034] In this embodiment, the furnace wall 11 is a silicon nitride ceramic honeycomb porous heat exchange structure with channels distributed along the axial direction and a pore diameter of 3 mm. The furnace width is 150 mm. The top of the furnace is equipped with an ammonia inlet 12 and an air inlet 13, both of which are equipped with mass flow meters for precise control of the ammonia and air ratio. The igniter 14 is a high-voltage electric arc igniter 14.

[0035] In the outer cracking zone 2, a spiral catalyst bed 21 is used, with a Cu-Zn-Al catalyst, a pitch of 1.5 mm, and a width of 80 mm. The space between the catalyst bed 21 and the furnace wall 11 in the combustion zone is filled with silicon nitride-based ceramic thermal grease, 5 mm thick, with a thermal conductivity of 10 W / (m²). K), with a volume shrinkage rate of 0.3% at 800℃; six temperature sensors 23 are K-type thermocouples symmetrically embedded in the inner wall of the bed; the cooling jacket 24 is an annular cavity, the cooling medium is No. 320 heat transfer oil, and a cooling medium circulation pump is equipped to control the flow rate of the heat transfer oil.

[0036] The tail mixing and purification zone 3 is sequentially configured with a condenser 32, a molecular sieve dryer 33, and a deoxygenation module 34 to remove impurities from the mixed gas.

[0037] In this embodiment, the feed rates of ammonia and air are controlled by a mass flow meter, with a molar ratio of oxygen to ammonia of 1.1. The ammonia feed rate is 10 m³ / h, and the air feed rate is 27.5 m³ / h. Ignition 14 is started, and ammonia undergoes oxygen-deficient combustion in the central combustion zone 1, maintaining the combustion temperature at 880°C. Liquid methanol is vaporized in a vaporizer (vaporization temperature 120°C) and then introduced into the spiral catalyst bed 21 through the methanol vapor inlet 25 at a flow rate of 0.2 m / s. Through heat transfer from the honeycomb porous furnace wall 11 and fluidized heat dissipation from the spiral flow channel, combined with the cooling oil flow rate (initial flow rate 10 L / min) adjusted by the closed-loop temperature control module, the pyrolysis temperature is stabilized at 275°C. Combustion products (high-temperature N2 + water vapor) and cracked gas (CO + H2) are mixed in the mixed gas guide cavity 31, cooled to 40°C by condenser 32 (removing most of the moisture), and then passed through molecular sieve dryer 33 (dew point reduced to -45°C) and deoxygenation module 34 (removing trace amounts of oxygen), and finally output as N2 + CO + H2 mixed gas that meets the process requirements from mixed gas outlet 35.

[0038] By combining a honeycomb porous heat exchange structure with ceramic thermal paste, the thermal resistance of the heat exchange interface is significantly reduced, and the heat exchange efficiency is improved by more than 30% compared with the traditional flat plate heat exchange structure. The synergistic effect of the spiral bed and closed-loop temperature control keeps the temperature fluctuation in the pyrolysis zone within ±5℃, effectively preventing catalyst deactivation due to temperature fluctuations. The prepared N2+CO+H2 mixed gas has a uniform and stable composition, with no obvious oxidation or decarburization impurities, which fully meets the atmosphere requirements for heat treatment of high carbon steel.

[0039] Comparative example: Understandably, while employing the same coaxially nested central combustion zone 1, peripheral pyrolysis zone 2, and tail mixing and purification zone 3, no structural optimization design was implemented. The furnace wall 11 of the central combustion zone 1 is a flat, heat-resistant steel wall, and the catalyst bed 21 has a cylindrical structure. No highly thermally conductive heat exchange interface is provided between the catalyst bed and the furnace wall 11 of the combustion zone. The remaining device parameters are consistent with Example 1, and the system operates under the same process conditions.

[0040] The comparative flat-plate furnace wall 11, lacking a dedicated thermally conductive filling layer, results in high thermal resistance at the heat exchange interface, insufficient heat transfer, and a heat exchange efficiency of only 60%~65%, far lower than the over 85% of this invention. A significant amount of heat is lost during ammonia combustion, requiring additional electric or gas heating to maintain methanol cracking requirements, significantly increasing energy consumption. The cylindrical catalyst bed 21 exhibits uneven airflow distribution, leading to localized overheating or insufficient heat, and lacks a closed-loop temperature control module. Temperature fluctuations in the cracking zone range from ±15℃ to ±20℃, exceeding the optimal temperature range for methanol cracking (270~280℃). These drastic temperature fluctuations cause rapid sintering and loss of the active components of the Cu-Zn-Al catalyst. After 500 hours of continuous operation, the catalyst's cracking activity decreases by more than 30%, and the methanol cracking rate drops below 90%, necessitating frequent shutdowns to replace the catalyst, resulting in high maintenance costs. Temperature fluctuations and catalyst activity decay cause fluctuations in the H2 ratio in the cracked gas to ±5%~±8%, resulting in an uneven overall gas mixture composition that fails to meet the purity requirements for high-carbon steel precision heat treatment.

[0041] While the specific embodiments of the present invention have been described above in conjunction with the accompanying drawings, this is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art without creative effort based on the technical solutions of the present invention are still within the scope of protection of the present invention.

Claims

1. An ammonia-methanol coupled gasification device, characterized in that, It includes a central combustion zone, a peripheral pyrolysis zone, and a tail mixing and purification zone arranged coaxially. The central combustion zone includes a furnace wall with a honeycomb porous heat exchange structure. The peripheral pyrolysis zone is located outside the central combustion zone and has a catalyst bed with a spiral flow guiding structure inside. A high-temperature resistant and heat-conducting filling layer is provided between the catalyst bed and the furnace wall of the central combustion zone. The tail mixing and purification zone is connected downstream of the central combustion zone and the peripheral pyrolysis zone and is used to mix and purify the combustion products from the central combustion zone and the pyrolysis gas from the peripheral pyrolysis zone.

2. An ammonia-methanol coupled gas generation plant as claimed in claim 1, wherein, The honeycomb porous heat exchange structure is made of silicon nitride ceramic. The honeycomb porous heat exchange structure includes several axially distributed channels along the furnace wall, and the diameter of the axial channels is set between 2 and 5 mm.

3. The ammonia-methanol coupled gas making plant of claim 1, wherein, The catalyst bed contains catalyst particles, and the pitch of the spiral flow guiding structure is set to 3 to 5 times the diameter of the catalyst particles.

4. The ammonia-methanol coupled gas making plant of claim 1, wherein, The high-temperature resistant thermally conductive filling layer is a silicon nitride-based ceramic thermally conductive paste or a flexible graphite pad.

5. An ammonia-methanol coupled gas generating plant as claimed in claim 4, wherein, The silicon nitride-based ceramic thermal paste is configured to have a thermal conductivity of not less than 8 W / m Kelvin and a volume shrinkage rate of not more than 0.5% when operating continuously at 800 degrees Celsius.

6. An ammonia-methanol coupled gas generation plant as claimed in claim 1, wherein, The peripheral pyrolysis zone also includes multiple temperature sensors installed on the inner wall of the catalyst bed and a cooling jacket installed outside the device. The multiple temperature sensors and the cooling jacket are connected in communication with an external temperature control unit to form a closed-loop temperature control module.

7. The ammonia-methanol coupled gasification apparatus as described in claim 6, characterized in that, The multiple temperature sensors are evenly distributed at predetermined intervals along the axial direction of the catalyst bed, and the cooling jacket is configured as a ring structure with a cooling medium inside.

8. The ammonia-methanol coupled gasification device as described in claim 1, characterized in that, The tail mixing and purification zone includes, in sequence along the airflow direction, a mixed gas guide cavity, a condenser, a molecular sieve dryer, a deoxygenation module, and a mixed gas outlet.

9. The ammonia-methanol coupled gasification device as described in claim 1, characterized in that, The top of the central combustion zone is provided with an ammonia inlet and an air inlet, and an igniter is provided at the ammonia inlet. The top of the peripheral pyrolysis zone is provided with a methanol vapor inlet.

10. A method of using an ammonia-methanol coupled gasification apparatus as described in any one of claims 1-9, characterized in that, include: Ammonia and air are introduced into the central combustion zone at a predetermined molar ratio for combustion, producing high-temperature flue gas. The vaporized methanol is fed into the spiral catalyst bed in the outer cracking zone for cracking reaction, while the cracking temperature is maintained within the set temperature range by the high-temperature resistant thermally conductive filling layer and the closed-loop temperature control module. The high-temperature flue gas from the central combustion zone is mixed with the pyrolysis gas from the peripheral pyrolysis zone in the tail mixing and purification zone, and then condensed, dried and deoxygenated in sequence to obtain a mixed gas.

Images