Ecological cement hydrogen combustion system

Abstract

The invention relates to the technical field of hydrogen production, and discloses an ecological cement hydrogen combustion system which comprises a hydrogen supply module, a premixed combustion module, a kiln, a waste heat recovery module and a control module. The hydrogen supply module is connected with the premixing combustion module through a graded pressure stabilizing pipeline, the combustion module is embedded into a kiln firing zone through a multi-layer annular ejector structure, and the waste heat recovery module comprises three stages of heat exchange units which are connected with a raw material preheating system and a generator set. The control module integrates a combustion parameter dynamic optimization algorithm and is provided with a safety interlocking system. Through mutual cooperation of the rotational flow flame stabilizing structure and the gradient heat insulation layer, adaptation of hydrogen energy combustion and a cement sintering process is achieved, the Pt / Al2O3 catalyst layer enables the hydrogen initiation temperature to be reduced to 400 DEG C, the flame temperature uniformity deviation is smaller than or equal to + / -15 DEG C, and the clinker sintering time is shortened by 18% compared with that of a traditional gas kiln.

Description

Technical Field

[0001] The present invention relates to the technical field of hydrogen production, in particular to an ecological cement hydrogen combustion system. Background Art

[0002] Hydrogen combustion has the characteristics of zero carbon emissions and high calorific value, but its application in cement kilns faces multiple technical challenges such as combustion stability regulation, high-temperature process adaptation, efficient utilization of waste heat and pollutant control. It is necessary to develop a hydrogen combustion system that is suitable for cement production processes.

[0003] In the traditional cement production process, the kiln combustion system mainly relies on fossil fuels such as natural gas and coal, and has the following significant problems: Taking natural gas as an example, the burner mostly adopts a single-channel injection structure, the hydrogen and air mixing efficiency is low, the flame temperature uniformity is poor, and the ignition temperature is high, resulting in a long clinker burning time. Summary of the Invention

[0004] In view of the shortcomings of the existing technology, the present invention provides an ecological cement hydrogen combustion system, which solves the problem of long clinker burning time in traditional cement production processes where burners mostly adopt a single-channel injection structure.

[0005] To achieve the above objectives, the present invention is implemented through the following technical solutions: an ecological cement hydrogen combustion system, including a hydrogen supply module, a premixed combustion module, a kiln, a waste heat recovery module and a control module; the hydrogen supply module is connected to the premixed combustion module through a graded pressure-stabilizing pipeline, the combustion module adopts a multi-layer annular injector structure embedded in the kiln firing zone, the waste heat recovery module includes three-stage heat exchange units respectively connected to the raw material preheating system and the generator set, and the control module integrates a dynamic optimization algorithm for combustion parameters and is configured with a safety interlock system.

[0006] By adopting the above technical solution, the staged premixing of hydrogen and air is achieved through multi-layer annular gaps. Combined with the premixed combustion module, a strong turbulent mixing field is formed, which increases the hydrogen-oxygen mixing efficiency by more than 40%, and the flame temperature uniformity deviation is ≤±15°C (50% improvement over the traditional single-channel structure), thereby shortening the clinker burning time by 18%.

[0007] Preferably, the waste heat recovery module comprises: a first-stage gas-gas heat exchanger connected to the kiln tail exhaust pipe, a second-stage gas-solid heat exchanger connected to the raw meal decomposition furnace, and a third-stage organic Rankine cycle generator set.

[0008] Preferably, the premixed combustion module includes guide vanes, a porous medium combustion plate and an infrared thermal imager, wherein the swirl angle is set to 30-45°, the porous medium porosity is 60-80%, and the infrared thermal imager provides real-time feedback of the flame morphology to the control module.

[0009] Preferably, the control module includes: a hydrogen-oxygen ratio adaptive adjustment unit, which dynamically adjusts the combustion equivalence ratio based on the kiln temperature curve and exhaust gas composition analysis; and a safety interlock unit that starts an emergency replacement program when a hydrogen concentration >2% LEL is detected.

[0010] Preferably, the hydrogen supply module adopts a dual-path gas supply system of a pressure swing adsorption hydrogen production unit and a liquid hydrogen storage tank, is equipped with a pressure buffer tank and a micro-leak detector, and has an adjustable working pressure range of 0.2-0.8MPa.

[0011] Preferably, the porous medium combustion plate is made of silicon carbide ceramic-based composite material, the surface of which is coated with a Pt / Al2O3 catalytic coating with a coating thickness of 50-100 μm, and the catalytic activity temperature is reduced to 400°C.

[0012] Preferably, a gradient insulation layer is provided on the inner wall of the kiln firing zone, comprising a nano-aerogel layer, a mullite fiber layer and a corundum castable layer, and the comprehensive thermal conductivity is ≤0.8W / (m·K).

[0013] Preferably, the system is equipped with an exhaust gas deep treatment unit, including a selective catalytic reduction unit and a membrane separation CO2 capture unit, and the NOx emission concentration is less than 50mg / Nm 3 , CO2 capture rate ≥90%.

[0014] Preferably, the control module integrates a digital twin system, and realizes real-time optimization of combustion parameters through reconstruction of the three-dimensional temperature field of the kiln and combustion simulation, and the fluctuation of the thermal system is controlled within the range of ±5°C.

[0015] Preferably, the system is equipped with an emergency energy switching module, which can automatically switch to the biomass gasification system when the hydrogen energy supply is interrupted, and the switching response time is less than 30 seconds.

[0016] The present invention provides an eco-cement hydrogen combustion system. It has the following beneficial effects:

[0017] 1. The present invention achieves the adaptation of hydrogen combustion and cement sintering process through the mutual cooperation of the swirl flame stabilization structure and the gradient insulation layer. The Pt / Al2O3 catalytic layer reduces the hydrogen ignition temperature to 400°C, and the flame temperature uniformity deviation is ≤±15°C, which shortens the clinker burning time by 18% compared with traditional gas kilns.

[0018] 2. This invention is based on a hierarchical energy utilization and digital twin dynamic control architecture. The first-stage gas-gas heat exchanger reduces the 800°C kiln tail exhaust gas to 400°C, increasing the raw meal decomposition rate by 12%. The third-stage ORC generator set uses 200°C low-temperature waste heat to generate 3.5 million kWh of electricity annually, with a comprehensive waste heat utilization rate of 87%. The DCS system optimizes heat flow distribution in real time based on the kiln tail temperature, grid load, and raw meal feed rate, and the deviation between power generation and process heat distribution is less than 5%.

[0019] 3. The present invention establishes a three-level protection chain of monitoring-response-recovery. TDLAS hydrogen concentration detection and acoustic emission pipeline crack monitoring can provide early warning of leakage risks 48 hours in advance; the electromagnetic shut-off valve and nitrogen purge establish a safety barrier within 0.5 seconds, with residual hydrogen less than 0.1% LEL. The biomass gasification system and burner are quickly reconfigured to achieve fuel switching. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a diagram of an eco-cement hydrogen combustion system of the present invention;

[0021] Figure 2 This is a schematic structural diagram of the waste heat recovery module of the present invention;

[0022] Figure 3 This is a schematic structural diagram of the premixed combustion module of the present invention;

[0023] Figure 4 This is a functional diagram of the control module of the present invention;

[0024] Figure 5 This is a cross-sectional view of the heat insulation layer of the kiln firing zone of the present invention;

[0025] Figure 6 Schematic diagram of the tail gas deep treatment unit of the present invention;

[0026] Figure 7 This is a schematic structural diagram of the hydrogen supply module of the present invention;

[0027] Figure 8 Schematic diagram of the emergency energy switching module of the present invention.

[0028] Among them, 1. Hydrogen supply module; 11. Pressure swing adsorption hydrogen production unit; 12. Liquid hydrogen storage tank; 13. Pressure buffer tank; 14. Micro leak detector; 2. Combustion module; 21. Guide vane; 22. Porous medium combustion plate; 221. Coating; 23. Infrared thermal imager; 3. Kiln; 31. Gradient insulation layer; 311. Nano aerogel layer; 312. Mullite fiber layer; 313. Corundum castable layer; 4. Waste heat recovery module; 41. Gas heat exchanger; 42. Solid heat exchanger; 43. Circulating generator set; 5. Control module; 51. Adjustment unit; 52. Safety interlock unit; 53. Digital twin system; 6. Exhaust gas deep treatment unit; 61. Catalytic reduction unit; 62. Capture unit; 7. Emergency energy switching module; 71. Biomass gasification system. DETAILED DESCRIPTION

[0029] The following will clearly and completely describe the technical solution of the present invention in conjunction with the accompanying drawings. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0030] Please see the attached Figure 1 -Attached Figure 3 An embodiment of the present invention provides an eco-cement hydrogen combustion system, including a hydrogen supply module 1, a premixed combustion module 2, a kiln 3, a waste heat recovery module 4 and a control module 5; the hydrogen supply module 1 is connected to the premixed combustion module 2 through a graded pressure-stabilizing pipeline, the combustion module 2 adopts a multi-layer annular injector structure embedded in the firing zone of the kiln 3, the waste heat recovery module 4 includes three-stage heat exchange units respectively connected to the raw material preheating system and the generator set, and the control module 5 integrates a dynamic optimization algorithm for combustion parameters and is configured with a safety interlock system.

[0031] Specifically, the first section: the pressure stabilization and safety assurance of the hydrogen supply module 1. The hydrogen supply module 1 adopts a dual-path gas supply architecture with a pressure swing adsorption hydrogen production unit 11 and a cryogenic liquid hydrogen storage tank 12 in parallel, and achieves 0.2-0.8MPa continuous pressure regulation through a three-stage pressure reducing valve group. Among them, the pressure swing adsorption hydrogen production unit 11 has a built-in molecular sieve adsorption tower, which can achieve a hydrogen purity of ≥99.95% at room temperature; the liquid hydrogen storage tank 12 is equipped with a vacuum insulation layer and a vaporizer, and the daily hydrogen supply can reach 2000Nm 3 The system integrates a pressure buffer tank 13 and a laser micro-leak detector 14 in the gas supply pipeline. When the hydrogen concentration is detected to be greater than 500ppm, an audible and visual alarm is triggered and a nitrogen purge program is started to ensure the safety and redundancy of the gas supply system.

[0032] The second section integrates catalysis and monitoring in the premixed combustion module 2. The module consists of eight circumferentially distributed groups of multi-layered annular injectors, each containing 30-45° adjustable swirl guide vanes 21 and a silicon carbide-based porous medium combustion plate 22. The surface of the silicon carbide-based porous medium combustion plate 22 is coated with a 50-100μm thick Pt / Al2O3 catalytic coating 221 via a plasma spray process, lowering the hydrogen ignition temperature to below 400°C. An infrared thermal imager 23 is embedded in the top of the module, capturing flame morphology data at 30 frames per second. A feature extraction algorithm is used to calculate the combustion stability coefficient in real time, automatically adjusting the hydrogen-oxygen mixture ratio when the fluctuation value exceeds 15%.

[0033] Section 3: Kiln 3 optimizes directional heat transfer. The firing zone of kiln 3 utilizes a gradient insulation design. From the inside out, these are: a 1mm-thick nano-aerogel layer 311 with a thermal conductivity of ≤0.02 W / m·K, a 50mm-thick mullite fiber layer 312 with a temperature resistance of 1300°C, and a 100mm-thick corundum castable layer 313 with an Al2O3 content of ≥90%. The combustion module 2 is embedded in the axial center of the kiln at a 15° angle. The spacing between the injector rings is 1 / 8 the kiln diameter, creating a composite swirl and DC flame field, ensuring a temperature uniformity deviation of ≤±20°C in the firing zone.

[0034] Section 4: A cascaded waste heat recovery system. Waste heat recovery module 4 comprises three energy recovery units connected in series: a first-stage gas-gas heat exchanger 41 conducts countercurrent heat exchange between the kiln exhaust gas (800-1000°C) and the raw meal, reducing the outlet exhaust temperature to 400°C. A second-stage gas-solid heat exchanger 42 uses the intermediate-temperature exhaust gas (400-600°C) to preheat the decomposition furnace feed, achieving a heat exchange efficiency of 78%. A third-stage organic Rankine cycle generator 43 converts the low-temperature waste heat (200-300°C) into electricity, generating ≥5000 kWh per day. A bypass valve is installed throughout the module to automatically allocate waste heat to different locations when the raw meal feed rate fluctuates, achieving an overall thermal efficiency of ≥85%.

[0035] The fifth section: Dynamic optimization mechanism of the control system. The control module 5 is equipped with a combustion optimization algorithm based on digital twins. It builds a three-dimensional thermal field model of the kiln with 12 temperature measurement points and 4 pressure measurement points, and performs an iterative calculation of the combustion parameters every 5 seconds. The system has a built-in hydrogen-oxygen equivalent ratio adaptive adjustment unit 51. According to the real-time exhaust gas composition, O2 content 3-5%, NOx < 50mg / Nm 3 The hydrogen flow rate is dynamically adjusted with a control accuracy of ±2%. The safety interlock unit 52 integrates triple monitoring of hydrogen concentration, flame signal, and pressure fluctuation. If any of these parameters exceeds the threshold (hydrogen concentration > 2% LEL / flame extinction / pressure fluctuation > 10%), nitrogen replacement is completed within 30 seconds and the system switches to the biomass gasification backup fuel system 71, ensuring continuous operation of the production line.

[0036] Please see the attached Figure 2 The waste heat recovery module 4 includes: a first-stage gas-gas heat exchanger 41 connected to the kiln tail exhaust pipe, a second-stage gas-solid heat exchanger 42 connected to the raw material decomposition furnace, and a third-stage organic Rankine cycle generator set 43.

[0037] Specifically, waste heat recovery module 4 employs a three-stage energy gradient recovery architecture. Its first-stage gas-to-gas heat exchanger 41 is a shell-and-tube countercurrent heat exchange structure composed of Incoloy 800H high-temperature alloy tubes. Kiln exhaust gas at 850-1000°C is introduced into the tube side, while the shell side directly exchanges heat with raw meal powder with a particle size of 80μm or less. The raw meal is preheated to 650°C before being fed into the decomposition furnace, while the exhaust gas temperature is simultaneously reduced to 400-450°C. This achieves a heat exchange efficiency of 68% ± 2%. The unit is equipped with an acoustic dust cleaning system that uses 20kHz high-frequency vibration to prevent dust accumulation on the tube walls, ensuring a continuous operation period of 30 days or more.

[0038] The secondary gas-solid heat exchanger 42 utilizes a spiral propulsion design. Its rotating cylinder is welded with 310S stainless steel fins on its inner wall. Operating at a speed of 3-5 rpm, the cylinder conducts turbulent heat exchange between the 400-600°C medium-temperature exhaust gas and the 5-10mm lumpy raw meal. After the raw meal is heated to 300°C, it enters the preheater, where the exhaust gas temperature drops to 200-250°C. This unit features a rotating scraper mechanism at the feed end. Its inclination angle is adjustable from 15-30° via a PLC, effectively preventing raw meal crusting and clogging, increasing heat exchange efficiency to over 75%.

[0039] The three-stage organic Rankine cycle generator unit 43 features a dual-fluid system. The primary circuit uses R245fa as the circulating fluid. The evaporator, with a corrugated plate structure, utilizes low-temperature exhaust gas (200-300°C) to heat the working fluid to 120°C saturated steam, which drives the screw expander for power generation. The auxiliary circuit uses a water-ethylene glycol solution to recover waste heat (80-150°C), which is then heated by a heat pump and fed into the plant's heating system. Each unit has a rated power of 500kW and can generate up to 3.5 million kWh of electricity annually. The working fluid filling rate is controlled to within ±1.5%.

[0040] Please see the attached Figure 3 The premixed combustion module 2 includes a guide vane 21, a porous medium combustion plate 22 and an infrared thermal imager 23, wherein the swirl angle is set to 30-45°, the porous medium porosity is 60-80%, and the infrared thermal imager 23 provides real-time feedback of the flame shape to the control module 5; the porous medium combustion plate 22 adopts a silicon carbide ceramic-based composite material, and the surface is coated with a Pt / Al2O3 catalytic coating 221, the coating 221 has a thickness of 50-100 μm, and the catalytic activity temperature is reduced to 400°C.

[0041] Specifically, the premixed combustion module 2 is composed of 12 groups of swirl flame stabilization units evenly distributed in the circumference, and each group of units includes a composite structure of adjustable guide blades 21 and porous medium combustion plates 22. The guide blades 21 are formed by laser cutting of Inconel718 high-temperature alloy, and the blade installation angle is steplessly adjusted in the range of 30-45° by a servo motor to form a swirl field with a diameter of Φ200-300mm. The swirl number Sn is controlled in the range of 0.6-1.2, so that a stable recirculation zone is formed at the root of the flame. The porous medium combustion plate 22 is based on silicon carbide fiber reinforced SiC ceramics and is prepared by gel injection molding technology. The pore gradient is set to 0.5-2mm, the porosity is 62%±3%, and the specific surface area is 800m 2 / m 3 , ensuring that the hydrogen and oxygen mixture completes turbulent mixing and pre-reaction within the plate.

[0042] The surface of the porous medium combustion plate 22 is coated with a Pt / Al2O3 catalytic coating 221 by atmospheric plasma spraying, wherein the Pt loading is 0.8wt% and the thickness of the coating 221 is controlled by a laser thickness gauge to be 80±10μm. After heat treatment at 800℃ / 4h, the catalytic coating 221 forms a nano-scale porous structure with an average pore size of 50nm, which reduces the hydrogen ignition temperature from the conventional 650℃ to 395℃ and the CO emission concentration to 15mg / Nm 3 A 50μm-thick NiCrAlY transition layer is placed between coating 221 and the substrate. It survived 100 cycles of thermal shock testing at 1200°C without peeling and has a service life of over three years. The infrared thermal imager 23 is equipped with a 640×512 pixel uncooled focal plane detector with a spectral response range of 3-5μm, capturing flame radiation signals at a 50Hz sampling rate. The system's built-in image processing algorithm generates a real-time combustion stability assessment report by extracting three characteristic parameters: flame area fluctuation rate <8%, center of mass offset <5mm, and temperature uniformity index ≥0.92. When a flame oscillation frequency >20Hz or a temperature difference >150°C in a local high-temperature zone is detected, the control module 5 adjusts the hydrogen flow rate and swirl angle within 200ms to ensure that combustion efficiency remains at 98.5% ±0.3%.

[0043] Please see the attached Figure 4 The control module 5 includes: a hydrogen-oxygen ratio adaptive adjustment unit 51, which dynamically adjusts the combustion equivalence ratio based on the kiln temperature curve and exhaust gas composition analysis; a safety interlock unit 52 that starts an emergency replacement program when a hydrogen concentration greater than 2% LEL is detected.

[0044] Specifically, the control module 5 integrates a multi-physics field coupling control algorithm, and its hydrogen-oxygen ratio adaptive adjustment unit 51 collects the temperature distribution of the 1200-1450℃ firing zone in the kiln in real time through 12 K-type thermocouples, and combines the online mass spectrometer to analyze the exhaust gas components O2: 3.2-4.8%, NOx: ≤45mg / Nm3 、CO:≤18mg / Nm 3 Millisecond-level analysis dynamically calculates the optimal equivalence ratio (Φ0.95-1.05). The control unit utilizes a model predictive control (MPC) algorithm, performing fuel / air flow corrections every 500ms. A piezoelectric ceramic proportional valve increases hydrogen flow rate control accuracy to ±0.5 m / s. Combined with swirl angle adjustment, thermal system fluctuations are maintained at ≤±8°C.

[0045] Safety interlock unit 52 has a three-level protection system: the first-level monitoring layer deploys 8 TDLAS hydrogen concentration sensors with a detection limit of 0.1%LEL, and detection points are set every 2 meters along the gas supply pipeline; the second-level response layer activates an early warning when the hydrogen concentration is greater than 1.5%LEL and increases the ventilation volume to 20,000m 3 / h, when LEL>2%, the hard line interlock is triggered, the hydrogen main valve is cut off within 0.5 seconds and the nitrogen purge system is activated with a purge rate of 30m 3 / min; the third-level redundancy layer communicates with the emergency energy switching module 7 via the PROFINET bus, completing the disturbance-free switching of the biomass gasification system within 3 seconds and maintaining the heat load of the kiln 3 stable at more than 85% of the rated value.

[0046] The system, equipped with a real-time digital twin engine, constructs a three-dimensional thermodynamic model of the kiln containing 120,000 grid cells. It synchronizes field sensor data every two seconds and uses a deep learning algorithm to predict operating conditions over the next five minutes. When the model indicates a local temperature anomaly deviation greater than 50°C, it automatically generates three optimization scenarios and performs A / B testing. The control parameter self-learning cycle is shortened to 24 hours. The safety protection strategy utilizes a multi-parameter fusion judgment mechanism, integrating risk grading based on parameters such as hydrogen concentration change rate dC / dt > 5%LEL / min, flame oscillation frequency > 25Hz, and pressure fluctuation ΔP > 8kPa. This results in a false alarm rate of less than 0.1 per year, achieving a SIL2 safety integrity level.

[0047] Please see the attached Figure 7 The hydrogen supply module 1 adopts a dual-path gas supply system consisting of a pressure swing adsorption hydrogen production unit 11 and a liquid hydrogen storage tank 12, and is equipped with a pressure buffer tank 13 and a micro-leak detector 14. The working pressure range is adjustable from 0.2 to 0.8 MPa.

[0048] Specifically, the hydrogen supply module 1 adopts a dual-path complementary gas supply architecture. Its pressure swing adsorption hydrogen production unit 11 consists of four sets of parallel CMS molecular sieve adsorption towers. The filling capacity of a single tower is 800kg. Under the operating pressure of 0.8-1.2MPa, the raw gas coke oven gas is treated by four-stage pressure swing adsorption to produce hydrogen with a purity of ≥99.99%, a dew point of ≤-70℃, and a production capacity of 1500Nm 3 / h. The unit is equipped with a self-cleaning program, performing a 3-minute reverse depressurization operation every 12 hours to maintain a molecular sieve adsorption efficiency decay rate of less than 0.1% per month. Liquid hydrogen storage tank 12 utilizes a double-layer vacuum insulation structure, with a 06Cr19Ni10 stainless steel liner and a 150mm thick interlayer filled with vacuum perlite. The daily evaporation rate is ≤ 0.3%. The tank is integrated with a gasification and pressure regulation unit, which heats liquid hydrogen from -253°C to 15°C gaseous hydrogen via a three-stage plate-fin heat exchanger. The output pressure is continuously adjustable between 0.2 and 0.8 MPa via an electro-hydraulic servo valve, with a flow rate fluctuation rate of less than 1.5%. In emergency conditions, the dual-tank parallel system can continuously supply hydrogen for 48 hours, meeting the full load requirements of kiln 3.

[0049] The pressure buffer tank 13 adopts an annular cavity structure with a volume of 8m 3 , built-in multi-layer metal filter with a mesh size of 400, dynamically adjusts the pressure in the tank through the PID algorithm with a control accuracy of ±0.02MPa, effectively suppressing the pressure oscillation caused by the sudden change in the flow of the combustion module 2. The micro-leak detector 14 is equipped with 12 TDLAS sensor arrays, and monitoring points are set every 1.5m along the gas supply pipeline. The detection sensitivity is 1ppm. When the local hydrogen concentration is greater than 100ppm, the regional isolation valve is started within 0.5 seconds and the helium tracer positioning system is activated. The leakage point positioning error is less than 20cm. The dual-path gas supply system is switched through the OPC protocol: the pressure swing adsorption hydrogen production unit 11 is preferentially enabled during the power valley period, and the time-of-use electricity price is used to reduce energy consumption; during the peak period of hydrogen use, the liquid hydrogen storage tank 12 is automatically switched to supply gas, and the flow adjustment rate reaches 200Nm 3 / min. The system is equipped with dual redundant PLC controllers. If the primary controller fails, the backup system seamlessly takes over within 50ms, ensuring continuous gas supply. Field tests have shown that the module's pressure stability CV value reaches 0.8%, and hydrogen utilization rate exceeds 99.7%. Annual operation and maintenance costs are reduced by 40% compared to traditional single-circuit systems.

[0050] Please see the attached Figure 5 A gradient insulation layer 31 is provided on the inner wall of the firing zone of the kiln 3, comprising a nano-aerogel layer 311, a mullite fiber layer 312 and a corundum castable layer 313, with a comprehensive thermal conductivity of ≤0.8W / (m·K).

[0051] Specifically, the inner wall of the firing zone of the kiln structure 3 utilizes a three-layer gradient insulation layer 31: from the inside out, a nano-aerogel layer 311, a mullite fiber layer 312, and a corundum castable layer 313. Nano-aerogel layer 311 is produced via a sol-gel process, using SiO2 aerogel as a matrix and reinforced with 5wt% silicon carbide whiskers. It is applied to the kiln wall surface via a vacuum impregnation process, forming an ultra-thin 0.8-1.2mm insulation layer with a room-temperature thermal conductivity as low as 0.018W / (m·K) and the ability to withstand high-temperature airflow of 1250°C. The surface of this layer is equipped with a laser micro-hole array with an aperture of 50-80μm, which effectively reduces the risk of thermal stress cracking. The mullite fiber layer 312 is prepared using a wet vacuum forming process. It is composed of 3-5μm diameter mullite fibers with Al2O3 72%-78%, SiO2 22%-28% and a silica sol binder. After sintering at 1300℃, it forms a 50mm thick flexible insulation layer with a thermal conductivity of 0.15W / (m·K) at 800℃. 304 stainless steel corrugated anchors are embedded in the fiber layer and arranged in a 20×20cm grid. The tensile strength is ≥1.5MPa, ensuring that the expansion coefficient matches the inner and outer layer materials. CTE: 6.5×10 -6 / ℃, thermal shock stability 1100℃ water cooling for more than 30 times without peeling.

[0052] The corundum castable layer 313 is composed of plate-shaped corundum (Al₂O₃≥99%), α-Al₂O₃ fine powder, and silica powder in a ratio of 7:2:1. Vibration casting is performed using low-cement bonding technology. It has a thickness of 100mm. After drying at 150°C for 24 hours and heat treatment at 1450°C for 6 hours, the apparent porosity is ≤15%, and the room-temperature compressive strength is >80MPa. The surface of this layer is designed with zigzag grooves 8mm deep and 30mm apart. This increases the radiant heat exchange area, reducing the surface temperature by 60-80°C while enhancing the turbulent heat exchange efficiency with the kiln airflow.

[0053] Please see the attached Figure 6 The system is equipped with an exhaust gas deep treatment unit 6, including a selective catalytic reduction unit 61 and a membrane separation CO2 capture unit 62, and the NOx emission concentration is <50mg / Nm 3 , CO2 capture rate ≥90%.

[0054] Specifically, the tail gas deep treatment unit 6 adopts a denitrification-carbon capture double cascade process, and its selective catalytic reduction unit 61 is equipped with a honeycomb vanadium tungsten titanium catalyst V2O5-WO3 / TiO2, with a catalyst specific surface area of ​​≥280m 2 / g, with a pore size distribution of 3-5nm. Within the temperature window of 320-400℃, the NOx reduction efficiency is increased to 94%±1% through a dual-fluid ammonia injection system with an ammonia-nitrogen ratio of 0.85-0.95. The unit has a built-in 12-channel infrared temperature measurement array, which monitors the catalyst bed temperature deviation in real time to ≤±5℃. When the inlet NOx concentration fluctuates by more than 20%, the self-tuning PID algorithm completes the ammonia injection amount correction within 10 seconds to ensure that the outlet NOx concentration is stable at 38-45mg / Nm 3 Membrane separation CO2 capture unit 62 meets the ultra-low emission limits of GB4915-2013. It utilizes a three-stage spiral composite membrane module in series. The primary membrane is a polyimide hollow fiber membrane with a CO2 / N2 selectivity ≥200, the secondary membrane is a zeolite molecular sieve membrane with a CO2 permeability ≥3000 GPU, and the tertiary membrane is a metal-organic framework MOF-74 membrane. At an operating pressure of 2.5-3.0 MPa, the CO2 capture rate is ≥92.5% and the purity is >99.5%. The system integrates a variable frequency recompression unit, which uses the 80-120°C low-temperature heat source from the waste heat recovery module 4 to drive a heat pump, reducing capture energy consumption to 1.8 GJ / tCO2. The captured CO2 is treated in a -25°C low-temperature liquefaction unit to produce liquid CO2, which can be directly used for food-grade dry ice production or geological storage.

[0055] Exhaust gas deep treatment unit 6 is equipped with a multi-objective optimization control system, communicating in real time with combustion module 2 via the OPC-UA protocol to establish a NOx-CO2 emissions prediction model. When kiln 3 load changes by >15%, the SCR unit's ammonia injection rate and membrane module operating pressure are adjusted in advance to maintain system dynamic equilibrium. 30% of the captured CO2 is converted to methanol via a Cu-ZnO-Al2O3 catalyst in the catalytic conversion unit, achieving an 18% conversion rate, thus achieving carbon resource recycling. The unit is equipped with a self-diagnostic module that automatically triggers ultrasonic cleaning and thermal regeneration procedures when catalyst activity drops to 80% or membrane flux decays by >15%.

[0056] Please see the attached Figure 4 The control module 5 integrates the digital twin system 53, which realizes the real-time optimization of combustion parameters through the three-dimensional temperature field reconstruction and combustion simulation of the kiln, and controls the thermal system fluctuation within the range of ±5℃.

[0057] Specifically, control module 5 integrates a high-precision digital twin system 53, creating a virtual mirror image of all elements of kiln 3. Its core sensor network consists of a 128-channel thermocouple array, a 16-line laser thermometer, and a 4D radar level meter. This system collects data on kiln temperature, material distribution, and gas flow rate at a rate of 50 times per second. Using a coupled finite element method (FEM) and computational fluid dynamics (CFD) algorithm, the three-dimensional temperature field reconstruction error for 120,000 grid cells is controlled to within ±8°C. Combined with a combustion reaction kinetics model, this system simulates the hydrogen-oxygen mixing, ignition, and flame propagation processes in real time, achieving a prediction accuracy exceeding 95%.

[0058] The digital twin system 53 is equipped with an optimization engine based on deep reinforcement learning to maximize thermal efficiency ≥98% and minimize NOx <45mg / Nm 3 With a combined goal of maintaining a standard deviation of ≤6°C in temperature uniformity, the system generates a set of optimal control parameters every two seconds: hydrogen flow rate, swirl angle, and secondary air volume. The system employs a hybrid strategy of model predictive control (MPC) and fuzzy PID control, executing millisecond-level command distribution via edge computing nodes. This reduces burner power adjustment delay to 150ms, achieving a thermal system fluctuation of ≤±4.3°C, a 60% improvement in stability compared to traditional control methods.

[0059] Please see the attached Figure 8 The system is equipped with an emergency energy switching module 7, which can automatically switch to the biomass gasification system 71 when the hydrogen supply is interrupted, and the switching response time is less than 30 seconds.

[0060] Specifically, the emergency energy switching module 7 adopts a dual-redundant fuel supply architecture, which consists of a biomass gasification system 71, a high-pressure nitrogen purge unit 72, and a fuel adaptive control valve group 73. When the hydrogen concentration sensor detects a gas supply interruption or a pressure drop of more than 30%, the safety interlock unit 52 triggers a three-level emergency response within 0.5 seconds: the first level action closes the electromagnetic shut-off valve of the hydrogen main pipeline with an action time of less than 0.3 seconds, and the second level starts a nitrogen purge flow of 50m 3 / min, continue for 10 seconds to remove residual hydrogen, activate the biomass gasification system 71 in three stages and switch the burner spray gun structure synchronously. The biomass gasification system 71 is equipped with a two-stage circulating fluidized bed gasifier with a processing capacity of 5t / h. The fuel is wood pellets with a particle size of 8-30mm and a moisture content of ≤15%. The calorific value is ≥12MJ / Nm at 800-1000℃. 3 The CO+H2 content of the combustible gas is ≥35%. The cyclone dust removal efficiency of the gasified gas is 99%, and the tar content of the decoking tower is <10mg / Nm 3 And metal membrane filter particles <5mg / Nm 3 Finally, the gas is delivered to the combustion module 2 through the outlet pressure of the pressurized screw unit at 0.6MPa. The system has a built-in calorific value online analyzer, which updates the gas composition data every 2 seconds and dynamically adjusts the air-fuel ratio through a feedforward control algorithm to ensure that the heat load switching fluctuation is less than ±8%.

[0061] The adaptive fuel control valve assembly 73 integrates a quick-seal connection mechanism, a rotary fuel switching valve with a switching time of less than 3 seconds, and a dual-channel Venturi mixer. The spray gun in combustion module 2 is equipped with a replaceable nozzle assembly. When switching between hydrogen and biomass gas modes, the hydraulic drive unit changes the aperture from Φ2mm for hydrogen mode to Φ5mm for biomass gas mode within 15 seconds. The digital twin system 53 simultaneously loads a biomass combustion model and reconstructs the flame morphology based on real-time calorific value data, keeping kiln temperature fluctuations within ±25°C and returning to within ±5°C of the set value within 30 seconds.

[0062] Example 1

[0063] Application Scenario

[0064] A production line with an annual output of 1 million tons of cement requires a hydrogen energy utilization rate of >99% and a reduction of kiln heat loss by more than 20%.

[0065] Key configuration and technical parameters

[0066] Hydrogen supply module (1)

[0067] Dual-path redundant architecture:

[0068] Pressure swing adsorption hydrogen production unit (11): 4 sets of molecular sieve adsorption towers in parallel, operating pressure 1.0 MPa, hydrogen purity 99.99%, production capacity 1800 Nm 3 / h, using industrial by-product gas (such as methanol reforming gas) as raw material.

[0069] Liquid hydrogen storage tank (12): two tanks with a capacity of 50m each 3 The daily evaporation rate is 0.25%. The liquid hydrogen is gasified through a three-stage plate-fin heat exchanger with an output pressure of 0.6MPa. It is switched with the pressure swing adsorption unit through the OPC protocol, and hydrogen is produced first during the off-peak period.

[0070] Safety features: Pressure buffer tank (13) volume 10m 3 , pressure fluctuation CV value 0.7%; the micro leak detector (14) uses TDLAS array, with a detection accuracy of 1ppm. When a leak occurs, the pipeline is isolated within 0.3 seconds and helium positioning is started.

[0071] Kiln insulation and combustion integration

[0072] Gradient insulation layer (31):

[0073] Nano-aerogel layer (311): thickness 1.0 mm, thermal conductivity 0.015 W / (m·K), surface micropore array reduces thermal stress.

[0074] Mullite fiber layer (312): 50 mm thick, temperature resistance of 1300° C., thermal conductivity of 0.12 W / (m·K) (test value at 800° C.), and tensile strength of the corrugated anchor of 1.8 MPa.

[0075] Corundum casting material layer (313): 100mm thick, Al2O3 content 99%, sawtooth groove structure reduces surface temperature by 70°C, comprehensive thermal conductivity 0.7W / (m·K).

[0076] Combustion module (2): multi-layer annular injector embedding angle 15°, swirl blade (21) angle 40°, porous medium combustion plate (22) porosity 65%, Pt / Al2O3 coating thickness 90μm, hydrogen ignition temperature 400℃, flame temperature uniformity deviation ±12℃.

[0077] Effect: Energy efficiency improvement: kiln heat loss is reduced by 22%, thermal efficiency reaches 88%, and hydrogen is saved by about 150,000 Nm per year compared with traditional systems 3 , Safety redundancy: Dual-path gas supply switching without disturbance, in case of emergency, the biomass gasification system (71) takes over within 30 seconds to maintain a stable heat load.

[0078] Example 2

[0079] Application Scenario

[0080] A green building materials demonstration line is required to achieve near-zero NOx emissions, full CO2 capture, and self-powered by waste heat.

[0081] Key configuration and technical parameters

[0082] Waste heat recovery module (4)

[0083] Three-level energy cascade utilization:

[0084] The first-stage gas-gas heat exchanger (41) processes 800-1000°C waste gas, preheats the raw material to 680°C, cools the waste gas to 420°C, has a heat exchange efficiency of 70%, is equipped with an acoustic wave dust cleaning system (20kHz), and has a continuous operation cycle of 45 days.

[0085] Secondary gas-solid heat exchanger (42): medium temperature exhaust gas (400-550℃) preheats the decomposition furnace feed, and the raw material temperature rises to 320℃, with a heat exchange efficiency of 78%. Rotating scrapers prevent crusting.

[0086] Three-stage organic Rankine cycle (43): dual working fluid system, R245fa working fluid for power generation (500kW), water glycol for waste heat recovery for heating, comprehensive thermal efficiency 87%, annual power generation 4 million kWh.

[0087] Exhaust gas deep treatment and carbon recycling

[0088] Selective catalytic reduction (61): vanadium-tungsten-titanium catalyst with a specific surface area of ​​300m 2 / g, NOx reduction efficiency 95% at 350℃, outlet concentration 35mg / Nm 3 , the self-tuning error of ammonia injection amount is ±2%.

[0089] Membrane separation CO2 capture (62): three-stage spiral membrane assembly (polyimide + zeolite + MOF-74), operating pressure 2.8 MPa, capture rate 93%, purity 99.6%, energy consumption 1.7 GJ / tCO2, 30% of the captured CO2 is used for methanol synthesis (conversion rate 18%).

[0090] Control Collaboration

[0091] Digital twin system (53): 128-channel sensors reconstruct the three-dimensional temperature field in real time, with a prediction error of ±5°C, deep reinforcement learning optimizes combustion parameters, and thermal fluctuations of ±4°C.

[0092] Safety interlock: Warning when hydrogen concentration is greater than 1.5% LEL, hydrogen is cut off in 0.5 seconds when greater than 2% LEL, nitrogen purge is completed within 10 seconds, and kiln temperature fluctuation is ±20℃ when emergency switching to biomass gas (recovery within 30 seconds).

[0093] Effect, environmental protection index: NOx emission 35mg / Nm 3 The CO2 capture rate is 93%, achieving near-zero emissions. The captured CO2 is converted into approximately 2,000 tons of methanol annually. Circular Economy: Waste heat power generation meets 30% of the production line's electricity needs, reducing overall carbon emissions by 75%.

[0094] The following is a comparison table with existing technologies:

[0095]

[0096] Thermal efficiency: The embodiment improves thermal efficiency by 13-22% compared with traditional kilns through a gradient insulation layer (thermal conductivity ≤ 0.8W / (m·K)) and three-stage waste heat recovery.

[0097] NOx emissions: Relying on porous media catalytic combustion (Pt / Al2O3 coating reduces the ignition temperature to 400°C) and graded air distribution technology, Example 1 and Example 2 achieve 65% and 70% emission reductions respectively, exceeding the national standard ultra-low emission requirements.

[0098] CO2 capture: Example 2 achieves a 93% capture rate through membrane separation technology (three-stage spiral membrane assembly), and the captured CO2 builds a carbon circular economy.

[0099] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. An ecological cement hydrogen combustion system, characterized in that: The invention comprises a hydrogen supply module (1), a premixed combustion module (2), a kiln (3), a waste heat recovery module (4) and a control module (5); the hydrogen supply module (1) is connected to the premixed combustion module (2) via a graded pressure-stabilizing pipeline; the combustion module (2) adopts a multi-layer annular injector structure embedded in the firing zone of the kiln (3); the waste heat recovery module (4) comprises three-stage heat exchange units respectively connected to the raw material preheating system and the generator set; the control module (5) integrates a dynamic optimization algorithm for combustion parameters and is configured with a safety interlock system.

2. The ecological cement hydrogen combustion system according to claim 1, characterized in that: The waste heat recovery module (4) comprises: a first-stage gas-gas heat exchanger (41) connected to the kiln tail exhaust pipe, a second-stage gas-solid heat exchanger (42) connected to the raw material decomposition furnace, and a third-stage organic Rankine cycle generator set (43).

3. The ecological cement hydrogen combustion system according to claim 1, characterized in that: The premixed combustion module (2) comprises a guide vane (21), a porous medium combustion plate (22) and an infrared thermal imager (23), wherein the swirl angle is set to 30-45 degrees, the porous medium porosity is 60-80%, and the infrared thermal imager (23) provides real-time feedback of the flame morphology to the control module (5).

4. The ecological cement hydrogen combustion system according to claim 1, characterized in that: The control module (5) comprises: a hydrogen-oxygen ratio adaptive adjustment unit (51) for dynamically adjusting the combustion equivalence ratio based on a kiln temperature curve and exhaust gas composition analysis; and a safety interlock unit (52) for starting an emergency replacement program when a hydrogen concentration greater than 2% LEL is detected.

5. The ecological cement hydrogen combustion system according to claim 1, characterized in that: The hydrogen supply module (1) adopts a dual-path gas supply system of a pressure swing adsorption hydrogen production unit (11) and a liquid hydrogen storage tank (12), is equipped with a pressure buffer tank (13) and a micro-leakage detector (14), and has an adjustable working pressure range of 0.2-0.8 MPa.

6. The ecological cement hydrogen combustion system according to claim 3, characterized in that: The porous medium combustion plate (22) is made of silicon carbide ceramic-based composite material, and is coated with a Pt / Al2O3 catalytic coating (221) on its surface. The coating (221) has a thickness of 50-100 μm, and the catalytic activity temperature is reduced to 400°C.

7. The ecological cement hydrogen combustion system according to claim 1, characterized in that: The inner wall of the firing zone of the kiln (3) is provided with a gradient heat insulation layer (31), comprising a nano-aerogel layer (311), a mullite fiber layer (312) and a corundum castable layer (313), and the comprehensive heat conductivity coefficient is ≤0.8W / (m·K).

8. The ecological cement hydrogen combustion system according to claim 1, characterized in that: The system is equipped with an exhaust gas deep treatment unit (6), comprising a selective catalytic reduction unit (61) and a membrane separation CO2 capture unit (62), with a NOx emission concentration of <50 mg / Nm3 and a CO2 capture rate of ≥90%.

9. The ecological cement hydrogen combustion system according to claim 1, characterized in that: The control module (5) is integrated with a digital twin system (53), and realizes real-time optimization of combustion parameters through reconstruction of the three-dimensional temperature field of the kiln (3) and combustion simulation, and controls the fluctuation of the thermal system within the range of ±5°C.

10. An eco-cement hydrogen combustion system according to any one of claims 1 to 9, characterized in that: The system is equipped with an emergency energy switching module (7) which can automatically switch to the biomass gasification system (71) when the hydrogen energy supply is interrupted, and the switching response time is less than 30 seconds.

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