Method and device for blending combustion of methane with hydrogen and capture of carbon dioxide

Abstract

The invention relates to the technical field of energy and power engineering, in particular to a method and a device for blending hydrogen with methane and capturing carbon dioxide. According to the specific technical scheme, the method comprises the following steps: (1) adjusting the volume ratio of hydrogen to biogas to be 1: (0.5-3) to form mixed gas; (2) the mixed gas is input into a combustion process optimization module to be combusted, the combustion temperature is monitored in real time, the proportion or the combustion rate of the mixed gas is regulated and controlled through a PID controller in combination with a dung beetle algorithm, and the temperature is kept at 600-1000 DEG C; (3) high-temperature water vapor generated by hydrogen combustion is recycled through a condensing device in the combustion process optimization module; and (4) the desulfurized gas enters a carbon dioxide capturing and sealing module to obtain liquid CO2, the liquid CO2 is subjected to low-temperature pressure reduction to form dry ice particles, and the dry ice particles are packaged and stored. The problems that in the prior art, emission of NOx and CO2 is high, the mixing control precision in the mixed gas combustion process is low, and by-products cannot be recycled are solved.

Description

Technical Field

[0001] The present invention relates to the field of energy and power engineering technology, and in particular to a method and device for burning biogas with hydrogen and capturing carbon dioxide. Background Art

[0002] Under the dual pressures of global energy transformation and environmental protection, hydrogen has attracted much attention as a clean and efficient energy source. Hydrogen, with its pollution-free characteristics that its combustion product is only water, is regarded as one of the important ways to achieve the goals of carbon peak and carbon neutrality. Hydrogen has many advantages as a fuel. Hydrogen exists mainly in a chemical state on the earth and is abundant in resources. It can be said to be an "inexhaustible" energy source. The heat released during its combustion is high (142MJ / kg), which is three times the calorific value of gasoline, and its combustion products are pollution-free and environmentally friendly. In addition, hydrogen can be used in various forms, can be produced in many ways, and can be converted into electricity, heat energy, etc. for use.

[0003] Although hydrogen is a clean fuel that produces relatively few pollutants during combustion, the problem of nitrogen oxides (NOx) produced during the combustion process has always been a focus of attention in the field of hydrogen energy utilization. In the context of environmental protection and sustainable development, NOx emissions produced by hydrogen combustion have become one of the key factors restricting its widespread application. The background of hydrogen combustion producing NOx stems from its unique combustion characteristics. When hydrogen burns, the flame propagation speed is fast (laminar flame speed 3.25m / s) and the combustion temperature is high. These characteristics lead to the easy generation of a large amount of thermal NOx during the combustion process. The generation of thermal NOx is closely related to the combustion temperature. The higher the temperature, the faster the NOx generation rate. In addition, the density of hydrogen is low (0.0899kg / m 3 ), the jet has weak penetration and is easily swept away by the high-speed airflow, resulting in localized high equivalence ratios and high-temperature hotspots, which in turn exacerbate NOx generation. Furthermore, directly venting the high-temperature water vapor produced by hydrogen combustion not only wastes a significant amount of heat energy but can also adversely affect equipment and the environment. Therefore, how to effectively reduce NOx emissions and optimize combustion temperatures while utilizing hydrogen as an energy source remains a pressing technical challenge.

[0004] Biogas is considered a promising alternative energy source due to its relatively low processing costs and slightly higher density than natural gas. Compared to other renewable fuels, such as syngas produced from the gasification of biomass and municipal solid waste, biogas offers significant advantages because it is efficiently converted directly from wet organic waste, requiring minimal pretreatment. However, biogas also has a significant drawback: its relatively low calorific value. The main reason for the low calorific value of biogas is the high proportion of carbon dioxide in the mixture (ranging from 20% to 60% by volume), depending on the digestion process used to produce the biogas and the source of the feedstock. While the carbon dioxide in biogas helps reduce pollutant emissions, it also has a negative impact on the overall combustion characteristics of the biogas. Specifically, a high carbon dioxide content in biogas leads to a narrower flammability range, slower laminar flame speeds, and lower flame temperatures.

[0005] Gas mixing systems are systems that produce a specific gas mixture using mixing theory. Currently, gas mixing systems are widely used in fields such as biological research, environmental monitoring, and instrument calibration. Consequently, these systems place higher standards on various technical parameters, particularly accuracy and response time, placing higher demands on the control algorithms and controller design. PID controllers are widely used in industrial process control, including mixed gas composition control. By combining proportional (P), integral (I), and differential (D) functions, PID controllers monitor gas composition ratios in real time and adjust gas flow rates according to set target values to ensure a stable gas mixture composition ratio. PID controllers have a simple structure and are easy to implement. They are suitable for linear, time-invariant systems, offering rapid error response and excellent stability. However, when dealing with complex nonlinear or time-varying systems, more advanced control strategies or optimization algorithms may be needed to further enhance control performance.

[0006] The Dung Beetle Optimization (DBO) algorithm is a swarm optimization algorithm inspired by the natural behavior of dung beetles. It simulates dung beetle behaviors such as rolling dung balls, dancing, reproduction, and foraging. It optimizes the solution to a problem through steps such as population initialization, an update strategy, and an elite reverse learning strategy. During the population initialization phase, an initial population is randomly generated, with each individual representing a potential solution to the problem. The population position is updated through ball rolling, dancing, reproduction, and foraging behaviors, and the fitness of each individual is calculated. Finally, an elite reverse learning strategy is applied to update the elite individuals. This algorithm performs well in applications such as optimizing PID parameters, effectively improving optimization efficiency and accuracy.

[0007] In recent years, CO2 emissions have garnered significant attention. As a major greenhouse gas, large-scale CO2 emissions have caused global temperatures to rise, significantly impacting the global climate. Since fossil fuels remain the primary energy source worldwide, resulting in significant carbon emissions, countries have implemented policies such as carbon taxes and green energy subsidies to address climate change and reduce CO2 emissions. Carbon capture, utilization, and storage (CCUS) has been proposed as a highly effective carbon reduction technology. CO2 capture and storage (CCUS) involves three main steps: capture, storage, or utilization. The capture process is the primary source of energy consumption in CCS technology. Furthermore, existing carbon capture systems are energy-intensive and expensive, making them difficult to implement in small and medium-sized energy projects. Summary of the Invention

[0008] In response to the shortcomings of the existing technology, the present invention provides a method and device for burning biogas with hydrogen and capturing carbon dioxide, which solves the problems of high NOx and CO2 emissions, low mixing control accuracy in the mixed gas combustion process, and the inability to recycle by-products in the existing technology.

[0009] To achieve the above objectives, the present invention is implemented through the following technical solutions:

[0010] The present invention discloses a method for burning biogas with hydrogen and capturing carbon dioxide, comprising the following steps:

[0011] (1) In the mixed fuel dynamic control module, the volume ratio of hydrogen to biogas is adjusted to 1:0.5-3 to form a mixed gas;

[0012] (2) The mixed gas is input into the combustion process optimization module for combustion, the combustion temperature is monitored in real time, and the mixed gas ratio or combustion rate is controlled by a PID controller combined with the dung beetle algorithm to maintain the temperature between 600 and 1000°C;

[0013] (3) The high-temperature water vapor generated by hydrogen combustion is recovered by the condensation device in the combustion process optimization module, and the combustion tail gas is desulfurized by red mud slurry through the tail gas treatment module;

[0014] (4) The desulfurized gas enters the carbon dioxide capture and storage module, and is sequentially pre-compressed, dust-removed, and compressed to above 6.5 MPa and cooled to <25°C. After liquefaction, liquid CO2 is obtained through gas-liquid separation. The liquid CO2 is then depressurized at low temperature to form dry ice particles, which are then packaged and stored.

[0015] Preferably, in step (2), the dung beetle optimization algorithm is used to tune the PID parameters and construct a dual closed-loop control architecture:

[0016] Inner loop: Dynamic ratio of hydrogen and biogas components is achieved through improved PID parameters;

[0017] Outer loop: The dung beetle optimization algorithm performs global optimization every 5 minutes to adapt to fluctuations in raw gas composition.

[0018] Preferably, the specific steps are as follows:

[0019] (1) Using the dung beetle algorithm to optimize the proportional parameter k of the PID controller p , integration parameter k i , differential parameter k d , taking the absolute error of integration time as the guide, the following formula is obtained:

[0020]

[0021] Where t is time and e(t) is the system error, which is the difference between the expected output r(t) and the actual output c(t).

[0022] (2) Randomly generate the initial population, each individual represents a set of PID parameters [K p ,K i ,K d ], the formula is as follows:

[0023]

[0024] in, is the initial position of the i-th individual;

[0025] (3) Find the local optimal parameters through the following update strategy:

[0026] (3.1) Rolling behavior:

[0027]

[0028] Among them, α is the natural coefficient, which takes the value of 1 or -1, k1∈(0,0.2] is the deflection coefficient; b∈(0,01) is a constant, X ω is the global worst position;

[0029] (3.2) Dancing behavior:

[0030]

[0031] Among them, θ∈[0,π] is the deflection angle;

[0032] (3.3) Reproductive behavior:

[0033]

[0034] in, is the current local optimal position, L boundand U bound are the upper and lower bounds of the parameters, β1 and β2 are random vectors.

[0035] (3.4) Foraging behavior:

[0036]

[0037] Where: γ is the step size factor; F is a function that calculates the update direction based on the current individual, the optimal individual, and ITAE;

[0038] (3.5) Elite Reverse Learning:

[0039] After each iteration, the top 10% of the solutions in the population fitness are selected as elite solutions, and their reverse solutions are calculated:

[0040] X new =X elite +δ·(X upper bound -X elite )

[0041] Among them, δ is a random number that obeys the normal distribution; X upper bound It is the upper bound of the optimization problem; when the maximum number of iterations is reached or the convergence condition is met, the optimal PID parameters are output.

[0042] Preferably, in step (3), the red mud desulfurization treatment process is: mixing red mud and water in a mass ratio of 1:3 to 5 into a slurry, spraying it into a desulfurization device to react with the tail gas, neutralizing SO2 to generate sulfate by-products.

[0043] Accordingly, a device based on the method of burning biogas with hydrogen and capturing carbon dioxide is characterized by comprising a mixed fuel dynamic control module, a combustion process optimization module, an exhaust gas treatment module, and a carbon dioxide capture and storage module;

[0044] The mixed fuel dynamic control module includes a mass flow controller, a CO2 sensor and a PID controller, which are used to dynamically adjust the mixing ratio of hydrogen and biogas;

[0045] The combustion process optimization module includes a combustion chamber, the outlet of which is connected to a condensing device, a thermocouple sensor built into the combustion chamber and connected to a PID controller signal, a NOx real-time monitoring device is set at the outlet of the combustion chamber and connected to a mixed fuel dynamic control module;

[0046] The tail gas treatment module includes a red mud slurry spray tower and a by-product collection tank. The red mud slurry spray tower is provided with a swirl plate at the top, an ultrasonic atomizing nozzle in the middle, and an inclined vibrating screen at the bottom.

[0047] The carbon dioxide capture and storage module includes a pre-compressor, a dust removal filter, a main compressor, a condenser, a gas-liquid separator and a dry ice forming device which are connected in sequence.

[0048] Preferably, the combustion process optimization module also includes a condensing device and a furnace wall spraying system, the condensing device is connected to the combustion chamber outlet and is connected to the circulating water tank; the furnace wall spraying system includes a temperature sensor and a nozzle, and the furnace wall spraying system is connected to the circulating water tank and the inner wall of the combustion chamber.

[0049] Preferably, a high-temperature bypass is provided between the circulating water tank and the furnace wall spray system, and the high-temperature bypass is provided with a temperature sensor and a bypass valve, and the temperature sensor is used to monitor the water temperature in the circulating water tank in real time; when the water temperature is ≥80°C or the combustion chamber is >1200°C, the bypass valve automatically opens, triggering the furnace wall spray system to start, spraying high-temperature water onto the inner wall of the combustion chamber, and using the latent heat of vaporization of the high-temperature water to absorb the heat in the combustion chamber, thereby reducing the furnace wall temperature.

[0050] Preferably, the combustion process optimization module adopts dynamic temperature control. When the temperature exceeds 1000°C, the system triggers three levels of response in sequence: first level response: reduce the volume ratio of hydrogen to biogas to 1:3 to increase the dilution effect of biogas; second level response: turn on the furnace wall spray system with a spray volume of 5 to 10 L / min; third level response: emergency injection of nitrogen to force cooling.

[0051] Preferably, the red mud slurry spray tower includes a desulfurization tower body, and the desulfurization tower body is provided with the following components from top to bottom:

[0052] Cyclone enhancement section: A single-stage cyclone plate is arranged on the upper part of the desulfurization tower body. The distance between adjacent cyclone plates is 100-400mm, the cyclone plate inclination angle is 25-40°, and the cyclone plate surface is provided with guide holes with an aperture of 10-15mm to enhance the gas-liquid turbulent mixing of tail gas and red mud slurry.

[0053] Atomization reaction section: An ultrasonic atomization nozzle group is arranged in a circular pattern in the middle of the desulfurization tower body. The operating frequency of the ultrasonic atomization nozzle group is 20-40kHz, the atomized particle size is ≤50μm, and the nozzle axis is at an elevation angle of 15-30° to the horizontal direction;

[0054] Separation and collection section: An inclined vibrating screen is set at the lower part of the desulfurization tower body. The screen has an inclination angle of 5 to 10 degrees and a screen hole diameter of 0.5 to 1.5 mm. The lower part of the inclined vibrating screen is connected to a by-product collection tank, and a screw conveyor is installed in the by-product collection tank.

[0055] Preferably, a venturi accelerator is embedded in the slurry supply pipeline of the ultrasonic atomizing nozzle group, the ratio of the throat diameter to the inlet diameter of the venturi accelerator is 1:3, the slurry flow rate is increased to 2-3 m / s, and an annular gas auxiliary channel is provided at the nozzle outlet, and the auxiliary gas flow rate is 10-15% of the slurry flow rate;

[0056] The inclined vibrating screen is driven by an eccentric connecting rod mechanism, with a vibration frequency of 20 to 50 Hz and an amplitude of 2 to 5 mm. The surface of the inclined vibrating screen is coated with a polytetrafluoroethylene wear-resistant layer with a thickness of 0.2 to 0.5 mm.

[0057] The present invention has the following beneficial effects:

[0058] 1. The present invention reduces the combustion temperature by dynamically blending hydrogen and biogas, effectively lowering the combustion temperature of hydrogen and thereby slowing the generation of thermal NOx. This is because NOx generation is closely related to combustion temperature, and lowering the temperature helps reduce NOx emissions, which is of great significance for addressing environmental issues in hydrogen energy utilization. The mixed use of biogas and hydrogen can also optimize the combustion process. The combustible components in the biogas can synergistically combust with the hydrogen, improving combustion stability and efficiency. Furthermore, the addition of biogas can improve the jet diffusion capacity of hydrogen, reducing the problems of high local equivalence ratios and high-temperature hotspots, further reducing NOx generation.

[0059] 2. This invention utilizes the DBO algorithm and PID controller to optimize the mixed gas ratio and combustion parameters in real time, effectively improving gas mixing accuracy and ensuring stable system operation. Furthermore, the integration of the DBO algorithm and PID solves the nonlinear control challenges of the gas mixing process. The ultrasonic atomization and vibrating screen design improves desulfurization efficiency, and the multi-stage compression coupling technology reduces carbon capture energy consumption.

[0060] 3. The present invention uses industrial solid waste (red mud) as a desulfurizer and recovers reaction by-products, thereby reducing operating costs and promoting a green process of "treating waste with waste."

[0061] 4. Recover the water vapor produced by combustion and the carbon dioxide in the exhaust gas, thereby improving economic benefits while achieving resource recycling and carbon emission reduction.

[0062] 5. The dynamic blending of the present invention reduces NOx emissions by 50%, the red mud desulfurization process reduces SO2 pollution, and the CO2 capture rate exceeds 90%, contributing to the "dual carbon" goals; the combustion water vapor recovery rate is ≥85%, which is used for cooling and spraying, saving 30% of water; dry ice packaging realizes the resource utilization of CO2 and reduces carbon tax expenditure; red mud replaces traditional desulfurizers and reduces costs by 40%, and the DBO algorithm optimization control reduces fuel waste by 10% to 15%, and the overall energy efficiency of the system is improved by 20%. BRIEF DESCRIPTION OF THE DRAWINGS

[0063] Figure 1 Flowchart for monitoring of each sensor in the method of the present invention;

[0064] Figure 2 This is a structural diagram of the red mud slurry spray tower. DETAILED DESCRIPTION

[0065] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the 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.

[0066] Unless otherwise specified, the technical means used in the embodiments are conventional means well known to those skilled in the art.

[0067] The present invention discloses a method for burning biogas with hydrogen and capturing carbon dioxide, comprising the following steps:

[0068] (1) In the mixed fuel dynamic control module, the volume ratio of hydrogen to biogas is dynamically adjusted to 1:0.5-3 according to the combustion conditions and the proportion of carbon dioxide to form a mixed gas; the carbon dioxide content of biogas (20%-60%) can dilute the hydrogen concentration and reduce the combustion temperature.

[0069] (2) The mixed gas is fed into the combustion process optimization module for combustion. The combustion temperature is monitored in real time by a thermocouple sensor. The mixed gas ratio or combustion rate is controlled by a PID controller combined with a dung beetle algorithm to maintain the temperature between 600 and 1000°C to suppress NOx generation.

[0070] Specifically, the mixed gas ratio is controlled using a dual closed-loop PID algorithm: the inner loop utilizes mass flow controller feedback (accuracy ±0.5% FS) for fast response (<50ms), while the outer loop utilizes the Dung Beetle Optimization (DBO) algorithm to globally optimize parameters every 5 minutes to adapt to fluctuations in biogas composition (mixing error <1.2% for a ±15% change in CO2 concentration). The Dung Beetle algorithm simulates ball rolling, dancing, reproduction, and foraging behaviors, using ITAE (Integral Time Absolute Error) as the optimization objective, dynamically adjusting PID parameters (Kp, Ki, Kd) to ensure system robustness under nonlinear, time-varying conditions.

[0071] (3) The high-temperature water vapor generated by hydrogen combustion is recovered through the condensation device in the combustion process optimization module, and the recovered water is used for furnace wall spray cooling and system circulation;

[0072] (4) The combustion exhaust gas passes through the exhaust gas treatment module and is desulfurized by red mud slurry. The red mud slurry is recycled and the by-products are recycled as resources.

[0073] Specifically: The process of red mud desulfurization treatment is: red mud and water are mixed into a slurry in a mass ratio of 1:3 to 5, and the slurry is sprayed into the desulfurization device to react with the tail gas to neutralize SO2 and generate sulfate by-products. The reaction formula includes: NaOH+SO2→Na2SO3+H2O, Ca(OH)2+SO2→CaSO3+H2O.

[0074] At the same time, red mud particles (with their large specific surface area) also absorb some SO₂ and NO₂. After the reaction, the slurry, separated by an inclined vibrating screen, falls into a recovery tank at the bottom of the desulfurization tower, while byproducts are discharged via a screw conveyor at the bottom of the desulfurization tower. Red mud slurry has a certain adsorption effect on NO₂ and a neutralizing effect due to its alkalinity. NO₂ is primarily composed of NO and NO₂, with NO₂ being an acidic gas (soluble in water to form nitric acid). The alkalinity of the red mud slurry neutralizes NO₂, producing a small amount of nitrate (such as NaNO₃ or Ca(NO₃)₂). The reaction equations are: NO₂ + H₂O → Na₂SO₃ + HNO₃, HNO₃ + NaOH → Na₂NO₃ + H₂O, and Ca(OH)₂ + HNO₃ → Ca(NO₃)₂ + H₂O. Furthermore, the iron oxides (such as Fe₂O₃) in the red mud have a certain redox capacity and can react with NO, partially converting it to NO₂, thereby increasing the solubility of NO₂. The reaction equation is: NO + O₂ → NO₂.

[0075] (5) The desulfurized gas enters the carbon dioxide capture and storage module, and is sequentially pre-compressed, dust-removed, and compressed to above 6.5 MPa and cooled to <25°C. After liquefaction, liquid CO2 is obtained through gas-liquid separation. The liquid CO2 is then depressurized at low temperature to form dry ice particles, which are then packaged and stored.

[0076] Furthermore, in step (2), the dung beetle optimization algorithm (DBO) is used to tune the PID parameters and construct a dual closed-loop control architecture:

[0077] Inner loop: Based on real-time feedback from the mass flow controller (accuracy ±0.5% FS), dynamic ratio of hydrogen and biogas is achieved through improved PID parameters;

[0078] Outer loop: The dung beetle optimization algorithm performs global optimization every 5 minutes to adapt to fluctuations in the raw gas composition (maintaining the mixing error <1.2% under conditions of CO2 concentration changes of ±15%).

[0079] This method employs an "inner loop first, then outer loop" tuning principle. First, the inner loop PID parameters are optimized to ensure fast dynamic response and no overshoot. Then, based on the system characteristics of the inner loop after stabilization, the outer loop PID parameters are adjusted to achieve steady-state accuracy. Global parameter tuning is also performed daily to adapt to seasonal variations in the biogas feedstock composition.

[0080] Among them, the proportional parameter k of the PID controller is optimized using the dung beetle algorithm. p , integration parameter k i , differential parameter k d , taking the integral time absolute error (ITAE) as the guide, the following formula is obtained:

[0081]

[0082] Where t is time and e(t) is the system error, which is the difference between the expected output r(t) and the actual output c(t).

[0083] The initial population is randomly generated, and each individual represents a set of PID parameters [K p ,K i ,K d ], the formula is as follows:

[0084]

[0085] in, is the initial position of the i-th individual;

[0086] Find the local optimal parameters through the following update strategy:

[0087] (1) Rolling:

[0088]

[0089] Among them, α is the natural coefficient, which takes the value of 1 or -1, k1∈(0,0.2] is the deflection coefficient; b∈(0,01) is a constant, X ω is the global worst position;

[0090] (2) Dancing

[0091]

[0092] Among them, θ∈[0,π] is the deflection angle;

[0093] (3) Breeding

[0094]

[0095] in, is the current local optimal position, L bound and U bound are the upper and lower bounds of the parameters, β1 and β2 are random vectors.

[0096] (4) Foraging behavior:

[0097]

[0098] Where: γ is the step size factor; F is a function that calculates the update direction based on the current individual, the optimal individual, and ITAE;

[0099] (5) Elite reverse learning:

[0100] After each iteration, the top 10% of the solutions in the population fitness are selected as elite solutions, and their reverse solutions are calculated:

[0101] X new =X elite +δ·(X upper bound -X elite )

[0102] Among them, δ is a random number that obeys the normal distribution; X upper bound It is the upper bound of the optimization problem; when the maximum number of iterations is reached or the convergence condition is met, the optimal PID parameters are output.

[0103] refer to Figure 1 As shown, the present invention discloses a device based on a method of burning biogas with hydrogen and capturing carbon dioxide, including a mixed fuel dynamic control module, a combustion process optimization module, an exhaust gas treatment module, and a carbon dioxide capture and storage module;

[0104] The mixed fuel dynamic control module includes a mass flow controller, a mixing chamber, a CO2 sensor and a PID controller for dynamically adjusting the mixing ratio of hydrogen and biogas; it also includes a pressure reducing valve and a primary desulfurization unit (iron oxide).

[0105] The combustion process optimization module includes a combustion chamber, the outlet of the combustion chamber is connected to a condensing device, a thermocouple sensor is built into the combustion chamber, the thermocouple sensor is connected to the PID controller signal, a NOx real-time monitoring device (such as a NOx sensor) is set at the outlet of the combustion chamber, and is connected to the mixed fuel dynamic control module; the combustion process optimization module also includes a condensing device and a furnace wall spray system, the condensing device is connected to the outlet of the combustion chamber and is connected to the circulating water tank, recovers water vapor and stores it in the circulating water tank; the furnace wall spray system includes a temperature sensor and a nozzle, and the furnace wall spray system is connected to the circulating water tank and the inner wall of the combustion chamber.

[0106] When the mixed gas is input into the combustion chamber, the temperature is monitored in real time by a thermocouple sensor, the NOx sensor monitors the NOx gas, and the PID-DBO combined control system adjusts the fuel input rate and ratio to stabilize the combustion temperature in the range of 600-1000℃.

[0107] The tail gas treatment module includes a red mud slurry spray tower and a by-product collection tank. A swirl plate is arranged at the upper part of the red mud slurry spray tower to enhance gas-liquid mixing, an ultrasonic atomizing nozzle is arranged in the middle part to improve the slurry dispersion, and an inclined vibrating screen is arranged at the bottom of the tower to separate desulfurization by-products (such as sulfate) in real time and transport them to the drying device through a bolt conveyor. The separated slurry falls into the recovery pool at the bottom of the tower.

[0108] The carbon dioxide capture and storage module includes a pre-compressor, a dust removal filter, a main compressor, a condenser, a gas-liquid separator and a dry ice forming device which are connected in sequence.

[0109] Furthermore, a high-temperature bypass is provided between the circulating water tank and the furnace wall spray system. The high-temperature bypass is provided with a temperature sensor and a bypass valve. The temperature sensor is used to monitor the water temperature in the circulating water tank in real time. When the water temperature is ≥80°C or the combustion chamber is >1200°C, the bypass valve automatically opens, triggering the furnace wall spray system to start, spraying high-temperature water onto the inner wall of the combustion chamber, and using the latent heat of vaporization of the high-temperature water to absorb the heat in the combustion chamber, thereby reducing the furnace wall temperature.

[0110] Furthermore, the combustion process optimization module adopts dynamic temperature control. When the temperature exceeds 1000°C, the system triggers three levels of response in sequence: the first response: reduce the volume ratio of hydrogen to biogas to 1:3 to increase the dilution effect of biogas; the second response: turn on the furnace wall spray system with a spray volume of 5 to 10L / min; the third response: emergency injection of nitrogen (purity ≥99.99%) to force cooling.

[0111] For further reference, Figure 2 As shown, except for special instructions and descriptions, the components involved are existing technologies (such as screens, nozzles, etc.), and the connection method of the components can be set according to actual needs. The red mud slurry spray tower includes a desulfurization tower body 1, and the desulfurization tower body 1 is provided with the following from top to bottom:

[0112] Cyclone enhancement section: A single-stage cyclone plate 111 is arranged on the upper part of the desulfurization tower body 1. The distance between adjacent cyclone plates is 100-400 mm, the cyclone plate inclination angle is 25-40 degrees, and the cyclone plate surface is provided with guide holes with an aperture of 10-15 mm to enhance the gas-liquid turbulent mixing of the tail gas and the red mud slurry;

[0113] Atomization reaction section: An ultrasonic atomization nozzle group 121 is arranged in a circular pattern in the middle of the desulfurization tower body 1. The operating frequency of the ultrasonic atomization nozzle group 121 is 20-40 kHz, the atomized particle size is ≤50 μm, and the nozzle axis is at an elevation angle of 15-30° to the horizontal direction;

[0114] Separation and collection section: An inclined vibrating screen 131 is provided at the lower part of the desulfurization tower body 1, with an inclination angle of 5 to 10 degrees and a screen aperture of 0.5 to 1.5 mm. A by-product collection tank 132 is connected below the inclined vibrating screen 131, and a screw conveyor is provided inside the by-product collection tank 132.

[0115] The slurry supply pipeline of the ultrasonic atomizing nozzle group 121 is embedded with a Venturi accelerator tube. The ratio of the throat diameter to the inlet diameter of the Venturi accelerator tube is 1:3. The slurry flow rate is increased to 2-3 m / s. An annular gas auxiliary channel is provided at the nozzle outlet. The auxiliary gas flow rate is 10-15% of the slurry flow rate.

[0116] The inclined vibrating screen 131 is driven by an eccentric connecting rod mechanism, with a vibration frequency of 20 to 50 Hz and an amplitude of 2 to 5 mm. The surface of the inclined vibrating screen 131 is coated with a polytetrafluoroethylene wear-resistant layer with a thickness of 0.2 to 0.5 mm.

[0117] Furthermore, the desulfurized gas is pre-compressed to a preset pressure. The compressed gas exiting the pre-compressor is then filtered through a dust filter and fed into a MOFs adsorption unit controlled by a flowmeter. The CO2 in the MOFs is then adsorbed and desorbed by hot air (approximately 70-100°C) or vacuum swing adsorption, yielding a high-purity CO2 gas stream. The high-concentration CO2 gas (99.9%) is then fed into the main compressor, where it undergoes three stages of boosting, increasing the pressure to a certain level. Once the CO2 pressure reaches a critical level of 6.5 MPa or higher and the temperature is below 25°C, the main compressor is cooled by a condenser, lowering the temperature of the mixed gas to below 25°C, liquefying the CO2. The liquefied CO2 and gaseous hydrogen are then fed into a gas-liquid separator, where the liquid carbon dioxide is separated and directly placed in a low-temperature, low-pressure environment (50°C, 0.1 MPa), causing it to expand and rapidly transform into a mixture of solid and gaseous phases. Among them, after the solid particles are collected, they can be further processed into dry ice blocks or rods through a compactor, and finally packaged and stored in a low-temperature environment to prevent them from sublimating; the gaseous part is input into the MOFs adsorption unit for recycling.

[0118] The MOFs material is one of Mg-MOF-74, UiO-66 or ZIF-8, and its specific surface area is 1500-3000m 2 / g, pore size is 0.3~0.5nm, CO2 adsorption capacity ≥5mmol / g (25℃, 0.1MPa).

[0119] In addition to the above-mentioned structure disclosed in the present invention, it should also include some valves, nitrogen cylinders, etc. set according to actual needs.

[0120] In the present invention, the combustion of biogas with hydrogen and the capture of carbon dioxide include the following steps:

[0121] S10: The hydrogen and biogas in the storage tank enter the mixing chamber according to the initial set ratio through different pressure reducing valves and mass flow controllers. The PID controller dynamically adjusts the volume ratio of hydrogen to biogas according to the carbon dioxide content of the mixed gas and the real-time combustion conditions.

[0122] S20. After the mixed gas is fed into the combustion chamber, the temperature is monitored in real time by a thermocouple sensor, and the PID-DBO combined control system adjusts the fuel input rate to stabilize the combustion temperature between 600 and 1000°C. The water produced by hydrogen combustion is recovered by a condensing device. When the temperature in the combustion chamber or circulating water tank is too high, spray cooling is performed. The water vaporization absorbs heat, further controlling the furnace temperature and reducing heat energy loss.

[0123] S30, combustion exhaust gas enters the red mud slurry desulfurization tower, where red mud and water are mixed into a slurry at a mass ratio of 1:3-5. After being dispersed by an ultrasonic atomization nozzle (particle size ≤50μm), it fully contacts the exhaust gas, removing SO2 through neutralization reaction and physical adsorption. The desulfurization tower is designed as a three-section structure: a swirl enhancement section (swirl plates tilted 25-40 degrees to enhance gas-liquid turbulence), an atomization reaction section (Venturi tube accelerates the slurry to 2-3m / s), and a separation and collection section (vibrating screen with an aperture of 0.5-1.5mm. The sulfate byproducts produced by the reaction are automatically separated and collected by the vibrating screen before being dried and recovered).

[0124] After S40 and desulfurization, the exhaust gas enters a multi-stage compression system, undergoing pre-compression for dust removal, main compression for boosting, and cooling through a condenser to liquefy the CO2. A gas-liquid separator introduces the liquid CO2 into a low-temperature, low-pressure environment, where it is converted into solid dry ice pellets through flash expansion. These are then compacted, packaged, and stored. Uncondensed CO2 is recycled back into the pre-compression system, minimizing energy consumption for carbon capture.

[0125] The present invention will be further described below with reference to specific embodiments.

[0126] Example 1

[0127] Taking a ceramic or glass factory as an example, the method and device for burning biogas with hydrogen and capturing carbon dioxide are as follows:

[0128] 1. Mixed fuel dynamic control module

[0129] 1. Equipment configuration and operation process

[0130] Premixing device: The mixing chamber is constructed of 316L stainless steel, with a parallel pressure reducing valve (model: GENTECG64-1000) and a mass flow controller (MFC, accuracy ±0.5% FS, response time <10ms) installed at the inlet. Hydrogen and biogas are fed into the mixing chamber through separate pipes, the inner walls of which are coated with a polytetrafluoroethylene (PTFE) anti-corrosion layer.

[0131] Dynamic ratio control:

[0132] Inner-loop control: Based on real-time flow data fed back from the MFC (sampling frequency 100Hz), an improved PID algorithm is used to adjust the pressure reducing valve opening, dynamically adjusting the hydrogen to biogas volume ratio within a range of 1:0.5 to 3. For example, when the CO2 concentration in the biogas rises to 50%, the system automatically increases the hydrogen ratio to 1:1.5 to maintain combustion stability.

[0133] Outer loop optimization: Call the Dung Beetle Optimization Algorithm (DBO) every 5 minutes to globally adjust the PID parameters (K p , K i , K d The initial DBO population was set to 100 parameter sets, with 50 iterations. The fitness function was ITAE (Integrated Time Absolute Error), with a target error of <1.2%. The optimization process was performed in real time on an industrial PC (Intel i7-12700H processor, 32GB memory). The optimal parameters were output and written to a Siemens S7-1500 PLC.

[0134] 2. Key parameters and verification

[0135] Mixed gas calorific value control: The calorific value of the mixed gas is monitored in real time by an online calorific value analyzer (model: YOKOGAWAZR202) to ensure that it is stable at 18-22MJ / m 3 .

[0136] Anti-interference test: Simulating biogas CO2 concentration fluctuations (±15%), the system completes the ratio adjustment within 10 seconds, and the mixing error is <1.0%.

[0137] 2. Combustion Process Optimization Module

[0138] 1. Combustion chamber design and temperature control strategy

[0139] Combustion chamber structure: It adopts a double-layer water-cooled wall design (inner layer material: Inconel 625, outer layer: carbon steel), with 8 groups of swirl burners arranged inside, and the flame length is controlled at 1.5~2.0m to avoid local high temperature.

[0140] Temperature monitoring and control:

[0141] Thermocouple arrangement: K-type thermocouples (accuracy ±1.5°C) are installed at the top, middle and outlet of the combustion chamber, with a sampling frequency of 10 Hz. The data are transmitted to the PID-DBO joint control system in real time.

[0142] Dynamic temperature control: When the temperature exceeds 1000°C, the system triggers three levels of response:

[0143] First-level response: reduce the hydrogen ratio to 1:3 to increase the dilution effect of biogas;

[0144] Secondary response: Open the furnace wall spray system with a spray volume of 5 to 10 L / min;

[0145] Level 3 response: Emergency injection of nitrogen (purity ≥ 99.99%) and forced cooling.

[0146] 2. Furnace wall spray system

[0147] Circulating water tank: volume 5m 3 , built-in titanium alloy coil heat exchanger, maintaining water temperature ≤60℃ through cooling tower (model: EVAPCOAT-250).

[0148] Spray logic: When the combustion chamber wall temperature ≥1000℃ or the water tank water temperature ≥80℃, the bypass valve (model: SAMSON3241) automatically opens, the spray pressure is 0.3~0.5MPa, the nozzle aperture is 1.0mm, the atomization angle is 60°, and the coverage area reaches 90% of the combustion chamber inner wall.

[0149] Heat recovery: The spray water absorbs heat and vaporizes, and the steam is recovered through the condenser (model: ALFALAVAL M6), with a recycling rate of ≥85%.

[0150] 3. Exhaust gas treatment module

[0151] 1. The tail gas treatment module includes a desulfurization tower body 1. The specific structure and parameter control are disclosed above.

[0152] 2. Utilization of by-products

[0153] The dried sulfate by-product (purity ≥ 90%) can be used in the building materials industry (such as gypsum board production), realizing a closed loop of "waste treatment with waste".

[0154] 4. Carbon dioxide capture and storage module

[0155] 1. Multi-stage compression and liquefaction

[0156] Pre-compression stage: Use a screw compressor (model: ATLAS COPCO GA37) to increase the tail gas pressure to 0.8 MPa and the temperature to ≤40°C;

[0157] Main compression stage: A three-stage reciprocating compressor (model: SIEMENS SGT-800) gradually increases the pressure to 6.5 MPa. A shell and tube heat exchanger is installed between each stage (cooling water temperature ≤ 15°C). The final liquefaction temperature is ≤ 25°C.

[0158] Gas-liquid separation: liquefied CO2 and uncondensed gas (mainly H2) are separated in a separator (material: 304SS, volume 2m 3 ) is layered, and the purity of liquid CO2 is ≥99.5%.

[0159] 2. Dry ice forming and storage

[0160] Flash expansion: Liquid CO2 enters the expansion tank (temperature -50°C) through a throttle valve (pressure drop 6.5MPa→0.1MPa), generating a mixture of solid dry ice (70%) and gaseous CO2;

[0161] Compaction and packaging: Dry ice pellets are formed into blocks (size 20 cm × 10 cm × 5 cm) using a twin-screw compactor (pressure 10 MPa) and packaged in a polyurethane insulation box (thickness 50 mm, thermal conductivity ≤ 0.02 W / m·K). The storage temperature is ≤ -30°C and the sublimation rate is <1% / month.

[0162] 3. Hydrogen recycling

[0163] The uncondensed hydrogen is purified by a dust removal filter (precision 0.1μm) and then returned to the premixing device, with a recycling rate of ≥98%.

[0164] 5. System linkage and automated control

[0165] 1. Centralized control system

[0166] Hardware configuration: industrial server (redundant design), distributed I / O module (model: ABB AC800M), HMI human-machine interface (resolution 1920×1080);

[0167] Software logic: Based on the SCADA system (WinCC), it integrates PID-DBO algorithm module, equipment status monitoring and alarm management (such as temperature exceeding the limit and pressure abnormality).

[0168] 2. Security protection mechanism

[0169] Emergency shutdown: when NOx concentration ≥ 200mg / m 3 Or when the CO2 capture rate is less than 85%, the system automatically cuts off the fuel supply and starts nitrogen purge;

[0170] Redundant design: Key equipment (such as compressors and condensers) use dual-machine hot standby, with switching time ≤ 1s.

[0171] In the description of the present invention, it should be understood that the terms "longitudinal", "transverse", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown by the device, and are only for the convenience of describing the present invention, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0172] The embodiments described above are merely descriptions of preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Without departing from the spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by persons skilled in the art should fall within the scope of protection defined by the claims of the present invention.

Claims

1. A method for burning biogas with hydrogen and capturing carbon dioxide, characterized by: The following steps are involved: (1) In the mixed fuel dynamic control module, the volume ratio of hydrogen to biogas is adjusted to 1:0.5-3 to form a mixed gas; (2) The mixed gas is input into the combustion process optimization module for combustion, the combustion temperature is monitored in real time, and the mixed gas ratio or combustion rate is controlled by a PID controller combined with the dung beetle algorithm to maintain the temperature between 600 and 1000°C; (3) The high-temperature water vapor generated by hydrogen combustion is recovered by the condensation device in the combustion process optimization module, and the combustion tail gas is desulfurized by red mud slurry through the tail gas treatment module; (4) The desulfurized gas enters the carbon dioxide capture and storage module, and is sequentially pre-compressed, dust-removed, and compressed to above 6.5 MPa and cooled to <25°C. After liquefaction, liquid CO2 is obtained through gas-liquid separation. The liquid CO2 is then depressurized at low temperature to form dry ice particles, which are then packaged and stored.

2. The method for burning biogas with hydrogen and capturing carbon dioxide according to claim 1, characterized in that: In step (2), the dung beetle optimization algorithm is used to tune the PID parameters and build a double closed-loop control architecture: Inner loop: Dynamic ratio of hydrogen and biogas components is achieved through improved PID parameters; Outer loop: The dung beetle optimization algorithm performs global optimization every 5 minutes to adapt to fluctuations in raw gas composition.

3. The method for burning biogas with hydrogen and capturing carbon dioxide according to claim 2, characterized in that: The specific steps are as follows: (1) Using the dung beetle algorithm to optimize the proportional parameter k of the PID controller p , integration parameter k i , differential parameter k d , taking the absolute error of integration time as the guide, the following formula is obtained: Where t is time and e(t) is the system error, which is the difference between the expected output r(t) and the actual output c(t). (2) Randomly generate the initial population, each individual represents a set of PID parameters [K p ,K i ,K d ], the formula is as follows: in, is the initial position of the i-th individual; (3) Find the local optimal parameters through the following update strategy: (3.1) Rolling behavior: Among them, α is the natural coefficient, which takes the value of 1 or -1, k1∈(0,0.2] is the deflection coefficient; b∈(0,01) is a constant, X ω is the global worst position; (3.2) Dancing behavior: Among them, θ∈[0,π] is the deflection angle; (3.3) Reproductive behavior: in, is the current local optimal position, L bound and U bound are the upper and lower bounds of the parameters, β1 and β2 are random vectors. (3.4) Foraging behavior: Where: γ is the step size factor; F is a function that calculates the update direction based on the current individual, the optimal individual, and ITAE; (3.5) Elite Reverse Learning: After each iteration, the top 10% of the solutions in the population fitness are selected as elite solutions, and their reverse solutions are calculated: X new =X elite +δ·(X upper bound -X elite ) Among them, δ is a random number that obeys the normal distribution; X upperbound It is the upper bound of the optimization problem; when the maximum number of iterations is reached or the convergence condition is met, the optimal PID parameters are output.

4. The method for burning biogas with hydrogen and capturing carbon dioxide according to claim 1, wherein: In step (3), the red mud desulfurization treatment process is: red mud and water are mixed into a slurry at a mass ratio of 1:3 to 5, and the slurry is sprayed into the desulfurization device to react with the tail gas to neutralize SO2 and generate sulfate by-products.

5. A device for the method of burning biogas with hydrogen and capturing carbon dioxide according to claims 1 to 4, characterized in that: It includes mixed fuel dynamic control module, combustion process optimization module, tail gas treatment module, and carbon dioxide capture and storage module; The mixed fuel dynamic control module includes a mass flow controller, a CO2 sensor and a PID controller, which are used to dynamically adjust the mixing ratio of hydrogen and biogas; The combustion process optimization module includes a combustion chamber, the outlet of which is connected to a condensing device, a thermocouple sensor built into the combustion chamber and connected to a PID controller signal, a NOx real-time monitoring device is set at the outlet of the combustion chamber and connected to a mixed fuel dynamic control module; The tail gas treatment module includes a red mud slurry spray tower and a by-product collection tank. The red mud slurry spray tower is provided with a swirl plate at the top, an ultrasonic atomizing nozzle in the middle, and an inclined vibrating screen at the bottom. The carbon dioxide capture and storage module includes a pre-compressor, a dust removal filter, a main compressor, a condenser, a gas-liquid separator and a dry ice forming device which are connected in sequence.

6. The device for burning biogas with hydrogen and capturing carbon dioxide according to claim 5, characterized in that: The combustion process optimization module also includes a condensing device and a furnace wall spraying system. The condensing device is connected to the combustion chamber outlet and is connected to the circulating water tank; the furnace wall spraying system includes a temperature sensor and a nozzle, and is connected to the circulating water tank and the inner wall of the combustion chamber.

7. The device for burning biogas with hydrogen and capturing carbon dioxide according to claim 6, characterized in that: A high-temperature bypass is provided between the circulating water tank and the furnace wall spraying system. The high-temperature bypass is provided with a temperature sensor and a bypass valve. The temperature sensor is used to monitor the water temperature in the circulating water tank in real time. When the water temperature is ≥80°C or the combustion chamber is greater than 1200°C, the bypass valve automatically opens, triggering the furnace wall spraying system to start, spraying high-temperature water onto the inner wall of the combustion chamber, and utilizing the latent heat of vaporization of the high-temperature water to absorb the heat in the combustion chamber and reduce the furnace wall temperature.

8. The device for burning biogas with hydrogen and capturing carbon dioxide according to claim 7, characterized in that: The combustion process optimization module adopts dynamic temperature control. When the temperature exceeds 1000℃, the system triggers three levels of response in sequence: the first response: reducing the volume ratio of hydrogen to biogas to 1:3 to increase the dilution effect of biogas; the second response: turning on the furnace wall spray system with a spray volume of 5 to 10L / min; the third response: emergency injection of nitrogen to force cooling.

9. The device for burning biogas with hydrogen and capturing carbon dioxide according to claim 5, characterized in that: The red mud slurry spray tower comprises a desulfurization tower body (1), and the desulfurization tower body (1) is provided with the following components in order from top to bottom: Cyclone enhancement section: a single-stage cyclone plate (111) is arranged on the upper part of the desulfurization tower body (1), the distance between adjacent cyclone plates is 100-400 mm, the cyclone plate tilt angle is 25-40 degrees, and a guide hole with a hole diameter of 10-15 mm is provided on the surface of the cyclone plate to enhance the gas-liquid turbulent mixing of the tail gas and the red mud slurry; Atomization reaction section: an ultrasonic atomization nozzle group (121) is arranged in a circular manner in the middle of the desulfurization tower body (1), the operating frequency of the ultrasonic atomization nozzle group (121) is 20 to 40 kHz, the atomized particle size is ≤ 50 μm, and the nozzle axis is at an elevation angle of 15 to 30 degrees to the horizontal direction; Separation and collection section: An inclined vibrating screen (131) is provided at the lower part of the desulfurization tower body (1), the screen has an inclination angle of 5 to 10 degrees, and a screen hole diameter of 0.5 to 1.5 mm. A by-product collection tank (132) is connected below the inclined vibrating screen (131), and a screw conveyor is provided inside the by-product collection tank (132).

10. The device for burning biogas with hydrogen and capturing carbon dioxide according to claim 9, characterized in that: The slurry supply pipeline of the ultrasonic atomizing nozzle group (121) is embedded with a Venturi accelerating tube, the ratio of the throat diameter to the inlet diameter of the Venturi accelerating tube is 1:3, the slurry flow rate is increased to 2-3 m / s, an annular gas auxiliary channel is provided at the nozzle outlet, and the auxiliary gas flow rate is 10-15% of the slurry flow rate; The inclined vibrating screen (131) is driven by an eccentric connecting rod mechanism, with a vibration frequency of 20 to 50 Hz and an amplitude of 2 to 5 mm. The surface of the inclined vibrating screen (131) is coated with a polytetrafluoroethylene wear-resistant layer with a thickness of 0.2 to 0.5 mm.

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