A one-dimensional simulation device for solid fuel moving bed filtration combustion gasification pyrolysis process

Abstract

This invention relates to a one-dimensional simulation model of a solid fuel moving bed filtration combustion gasification and pyrolysis process, belonging to the field of solid fuel combustion gasification simulation technology. It includes: an input module, an array setting module, an initialization module, a moving mesh module, a core calculation module, and a graph output module. This invention can be used for mixed combustion processes and operating conditions to simulate continuous industrial operations.

Description

Technical Field

[0001] This invention relates to a one-dimensional simulation method for a moving bed filtration combustion gasification pyrolysis process, belonging to the field of solid fuel combustion gasification simulation technology. Background Technology

[0002] Climate change, stringent emission standards, and the depletion of traditional energy sources are placing increasingly stringent demands on clean combustion technologies. In 2022, global annual CO2 emissions from combustion and industrial processes reached 3.67 billion tons. This figure is projected to increase further in 2023, posing a serious threat to human health and climate change. Fossil fuels are not a viable solution for meeting long-term energy and environmental needs. Furthermore, the traditional fuel supply chain needs upgrading to cope with the growing global population and its increasing energy demands. Against this backdrop, syngas production technologies have been developed. Hydrogen, with its high energy content (up to 141.9 MJ / kg), is an excellent alternative to fossil fuels. Syngas is primarily composed of H2 and CO, with smaller amounts of CO2, nitrogen, and methane. Syngas is a fuel in itself and is also used in the synthesis and production of some chemicals. Currently, syngas can be produced through thermochemical methods such as dry reforming, steam reforming, and partial oxidation. Fuzzy comprehensive evaluation of various hydrogen production technologies using fuzzy set theory shows that, from the perspective of contribution rate to environmental quality improvement, environmental benefits obtained through clean energy production, and the overall energy-economy-environment considerations, solid fuel gasification hydrogen production has the highest evaluation value and is the preferred gasification hydrogen production technology to be considered in the near and medium term.

[0003] Porous media combustion is a method for generating syngas through fuel combustion and gasification. It has advantages such as integration, miniaturization, and strong fuel adaptability, and generates low levels of pollutants. However, mixed filtration combustion within porous media is a complex process involving the coupling of three heat exchange modes: convection, conduction, and radiation. Fundamental issues such as the gasification reaction mechanism of solid fuels, the coupling laws between chemical reactions and flow, heat transfer, and mass transfer processes have not yet been clearly understood. Furthermore, existing observation equipment is limited. For example, the existing technology "Unsteady Simulation of Ignition of Turbulent Reactive Swirling Flow of Novel Design of Solid-Fuel Ramjet Motor" numerically studied the ignition and combustion stability of a novel solid-fuel ramjet engine (SFRJ), simulating the solid combustion process. However, the fuel is a pure solid, while the fuel in the solid fuel moving bed filtration combustion gasification and pyrolysis process contains inert porous media particles, thus the device cannot simulate this operating condition. The existing technology, "Application of Moving Mesh Technology in Computational Fluid Dynamics Numerical Simulation," applies moving mesh technology to numerical simulation of computational fluid dynamics based on harmonic mapping theory. This solves the problem that traditional fixed meshes cannot simulate large deformations and simulates the movement of oil inside a tank during swaying. However, for the solid fuel moving bed filtration combustion gasification and pyrolysis process, the reactor is a mixture of solid fuel particles and inert porous media, and the movement of materials throughout the entire reactor needs to be simulated. Therefore, the technology proposed in this paper cannot be applied to the mixed filtration combustion process. Solving these problems requires exploring methods combining simulation calculations. Mixed filtration combustion simulation is a comprehensive challenge involving multiphase flow, multiple scales, and multiple physics fields. Currently, existing simulation devices or commercial software can only simulate fixed bed conditions and cannot simulate moving bed conditions, i.e., continuous industrial operations; they can only analyze the combustion process in a fragmented manner.

[0004] Therefore, there is an urgent need to propose a one-dimensional simulation device for the solid fuel moving bed filtration combustion gasification pyrolysis process to solve the above-mentioned technical problems. Summary of the Invention

[0005] To address the aforementioned problems, a one-dimensional simulation apparatus for a solid fuel moving bed filtration combustion gasification and pyrolysis process is provided. A brief overview of the invention is given below to provide a basic understanding of certain aspects of the invention. It should be understood that this overview is not an exhaustive summary of the invention. It is not intended to identify key or essential parts of the invention, nor is it intended to limit the scope of the invention.

[0006] The technical solution of this invention:

[0007] A one-dimensional simulation device for a solid fuel moving bed filtration combustion gasification pyrolysis process includes:

[0008] Input module: Reads user-defined initial flow field values, including initial temperature, initial velocity, initial fuel blending ratio, and reaction mechanism-related parameters;

[0009] Array settings module: Defines the required array length based on the calculation parameters;

[0010] Initialization module: Use the initialization module to initialize the flow field; initialization includes assigning values ​​to the initial state of the flow field;

[0011] Moving grid module: As the flame spreads from the bottom to the middle of the reactor, the bottom of the reactor begins to feed and discharge materials in an orderly manner. To simulate this process, the moving grid module moves the reactor in an orderly manner to simulate the feeding and discharging process.

[0012] Core computing module: The calculation is performed in multiple time steps, and the device equations are calculated iteratively within each time step;

[0013] Chart Output Module: After the calculation is completed, use the chart output module to output the simulation calculation values, including the temperature, CO, CO2, and O2 component concentrations of each grid.

[0014] Preferred input module includes:

[0015] Experimental parameter module: including the mixing ratio of fuel and inert porous media, the type of inert porous media, the volumetric flow rate of oxidant, fuel density, reactor length, particle size of inert media, mixed porosity of fuel and inert porous media, charging height, solid phase thermal conductivity and gas phase thermal conductivity;

[0016] The calculation parameters module includes the number of grids, the total number of calculation time steps, the time interval of the output files, the time interval of the output graphs, the number of iterations per time step, the convergence residuals per time step, and the file names of the residuals and output data per time step.

[0017] Reaction Mechanism Module: Includes homogeneous chemical reaction mechanisms and heterogeneous chemical reaction mechanisms. The reaction mechanism adopts a four-step reaction mechanism, as follows:

[0018]

[0019] The input mechanistic parameters include pre-exponential factor, activation energy, and temperature exponent;

[0020] Boundary conditions module: includes initial flow field temperature, ignition zone temperature, and ignition zone width percentage.

[0021] Preferred: Array setting module: Based on the length of the parameters input by the user in the input module, it is used to store the data of each variable.

[0022] Preferred: Initialization module: This module initializes the flow field using parameters input from the input module, converts temperature values ​​to Kelvin, and calculates the specific surface area SA of the porous medium. It's porosity. d p This refers to the characteristic diameter of an inert porous medium, used for simulation calculations.

[0023]

[0024] Preferred: Moving Grid Module: Initially off by default. When the flame propagates from the bottom to the middle of the reactor, the flame propagation speed is obtained by dividing half the length of the reactor by the time it takes for the flame to propagate from the bottom to the middle. Then, continuous feeding begins at the bottom of the reactor, with the feeding speed matching the flame propagation speed. Orderly discharge also begins at the bottom of the reactor, with the discharge speed matching the flame propagation speed. This stabilizes the flame in the middle region of the reactor, achieving stable operation. To simulate this process, at time T, the flame propagates to the middle of the reactor. At time T+Δt, the flame propagates to the next grid. At this time, the moving grid module adds a grid to the right end of the reactor, with internal parameters consistent with those after initialization. Simultaneously, a grid is removed from the left end of the reactor, ensuring the flame remains in the middle position of the reactor. The feeding and discharging process is simulated through relative grid movement.

[0025] Preferred: The chart output module outputs simulated calculation values ​​after the calculation is completed, including the temperature of solids and gases, and the concentrations of CO, CO2, and O2 components in each grid. The calculation is divided into multiple time steps, and the device equations are iteratively calculated in each time step. The iteration method uses the core calculation module for calculation. Therefore, after the calculation reaches the time interval defined by the user for outputting the chart, the module will be used to output the chart.

[0026] Preferred approach: The core calculation module iteratively solves the equations for the entire device, assuming that the fuel particles are non-volatile, water-free, have a constant particle size during combustion, and leave no component residue after combustion; the oxidant is an incompressible ideal gas, the solid fuel particles and inert medium particles are uniformly mixed, and the gas flow rate in the reactor remains constant; the device equations include gas phase energy equations, solid phase energy equations, mass equations, and component transport equations, and here it is assumed that the gas flow rate is constant, so there is no momentum equation; all equations are iterated using the Newton-Raphson iteration method for transient solution.

[0027] The present invention has the following beneficial effects:

[0028] This invention can be used in mixed combustion processes and operating conditions. After the oxidant enters the reactor, it undergoes a gasification and cracking reaction with solid fuel particles to produce carbon monoxide. The combustion zone is in the central region. The heat generated is used to gasify and crack the solid fuel in the mixture above the flame through radiation and heat conduction. The moving grid module makes the reactor move in an orderly manner in the direction of flame movement, simulating the feeding and discharging process through relative motion. At the same time, the radiation and convection heat transfer of the flame transfers excess heat to the inert porous medium, and with the discharge, heat is transferred to the oxidant in the feed pipe to preheat the oxidant so that the combustion temperature is higher than the adiabatic flame temperature, achieving a super-adiabatic combustion state. The higher combustion temperature can replace the role of the catalyst and accelerate the gasification and cracking of solid fuel. Since the combustion temperature is between 700-900℃, the formation of NOx can be largely avoided, realizing the simulation of continuous operation in industry. Attached Figure Description

[0029] Figure 1 This is a structural diagram of a one-dimensional simulation device for the solid fuel moving bed filtration combustion gasification pyrolysis process.

[0030] Figure 2 This is a schematic diagram of a mobile mesh module. Detailed Implementation

[0031] To make the objectives, technical solutions, and advantages of this invention clearer, the invention is described below with reference to specific embodiments shown in the accompanying drawings. However, it should be understood that these descriptions are merely exemplary and not intended to limit the scope of the invention. Furthermore, descriptions of well-known structures and technologies are omitted in the following description to avoid unnecessarily obscuring the concept of the invention.

[0032] Specific implementation method one: Combining Figure 1-2 This embodiment describes a one-dimensional simulation device for the solid fuel moving bed filtration combustion gasification and pyrolysis process. This device allows for the exploration of combustion details and the optimization of the process flow using simulation results. The main computation thread includes:

[0033] Input module: Reads user-defined initial flow field values, including initial temperature, initial velocity, initial fuel blending ratio, reaction mechanism-related parameters, and other calculation parameters; reaction mechanism-related parameters include the pre-exponential factor, activation energy, and temperature exponent of the R1-R4 reaction formulas;

[0034] The input module includes:

[0035] Experimental parameter module: including the mixing ratio of fuel and inert porous media, the type of inert porous media, the volumetric flow rate of oxidant, fuel density, reactor length, particle size of inert media, mixed porosity of fuel and inert porous media, charging height, solid phase thermal conductivity and gas phase thermal conductivity;

[0036] The calculation parameters module includes the number of grids, the total number of calculation time steps, the time interval of the output files, the time interval of the output graphs, the number of iterations per time step, the convergence residuals per time step, and the file names of the residuals and output data per time step.

[0037] The reaction mechanism module includes homogeneous and heterogeneous chemical reaction mechanisms. The reaction mechanism employs a four-step process to simulate combustion within an inert porous medium. The reaction mechanism is as follows:

[0038]

[0039] The input mechanistic parameters include the pre-exponential factor, activation energy, and temperature exponent; as shown in the table below:

[0040]

[0041] Boundary conditions module: includes initial flow temperature, ignition zone temperature, and ignition zone width percentage, defining the physical conditions on the boundary;

[0042] Array setting module: The input module reads the calculation parameters input by the user, defines the required array length based on the calculation parameters, and ensures sufficient storage space for data processing;

[0043] Array setting module: Based on the length of the parameters input by the user in the input module, it is used to store the data of various variables; variables include: the values ​​of all variables contained in the input module, array setting module, initialization module, moving grid module, chart output module, and core calculation module;

[0044] Initialization module: After the array is defined, the flow field is initialized using the initialization module; initialization includes assigning values ​​to the initial state of the flow field before starting the calculation; providing conditions for iterative calculation;

[0045] Initialization module: This module initializes the flow field using parameters input from the input module, converts temperature values ​​to Kelvin, and calculates the specific surface area SA of the porous medium. It's porosity. d p This refers to the characteristic diameter of inert porous media, used for simulation calculations;

[0046]

[0047] Moving grid module: As the flame spreads from the bottom to the middle of the reactor, the bottom of the reactor begins to feed material in an orderly manner and discharge material in an orderly manner. To simulate this process, the moving grid module moves the reactor in an orderly manner to simulate the feeding and discharging process.

[0048] Moving Grid Module: Initially disabled by default. When the flame propagates from the bottom to the middle of the reactor, the flame propagation speed is obtained by dividing half the reactor length by the time it takes for the flame to propagate from the bottom to the middle. Then, continuous feeding begins at the bottom of the reactor, with the feeding speed matching the flame propagation speed. Orderly discharge also begins at the bottom of the reactor, with the discharge speed matching the flame propagation speed. This stabilizes the flame in the middle region of the reactor, achieving stable operation. To simulate this process, the principle of the moving grid module is shown in the diagram below. At time T, the flame propagates to the middle of the reactor. At time T+Δt, the flame propagates to the next grid. At this time, the moving grid module adds a grid to the right end of the reactor, with internal parameters consistent with those after initialization. Simultaneously, a grid is removed from the left end of the reactor, ensuring the flame remains in the middle position of the reactor. The feeding and discharging process is simulated through the relative movement of the grids.

[0049] Chart Output Module: After the calculation is completed, the chart output module outputs the simulation calculation values, including the temperature, CO, CO2, and O2 component concentrations of each grid. The display is intuitive and easy to show to users. The various modules in the main calculation thread work together to efficiently and accurately generate the simulation results required by the user.

[0050] The chart output module outputs the simulated values ​​after the calculation is completed, including the temperature of the solid and gas in each grid, and the concentrations of CO, CO2, and O2 components. The calculation is divided into multiple time steps, and the device equations are iteratively calculated in each time step. The iteration method uses the core calculation module. Therefore, after the calculation reaches the time interval defined by the user to output the chart, the module will output the chart.

[0051] Core computing module: The calculation is divided into multiple time steps. Within each time step, the device equations are calculated iteratively. The iteration method uses the core computing module for calculation, which is accurate and stable.

[0052] The core calculation module iteratively solves the equations for the entire device. The device first assumes that the fuel particles are non-volatile, water-free, have a constant particle size during combustion, and leave no component residue after combustion; the oxidant is an incompressible ideal gas, the solid fuel particles and inert medium particles are uniformly mixed, and the gas flow rate in the reactor remains constant; the device equations include gas phase energy equations, solid phase energy equations, mass equations, and component transport equations. Here, it is assumed that the gas flow rate is constant, so there is no momentum equation; all equations are iterated using the Newton-Raphson iteration method for transient solutions;

[0053] After the oxidant enters the reactor, it undergoes a gasification and cracking reaction with the solid fuel particles to produce carbon monoxide. The combustion zone is in the central region. The heat generated is used to gasify and crack the solid fuel in the mixture above the flame through radiation and conduction. The moving grid module makes the reactor move in an orderly manner in the direction of flame movement, simulating the feeding and discharging process through relative motion. At the same time, the radiation and convection heat transfer of the flame transfers excess heat to the inert porous medium, and with the discharge, heat is transferred to the oxidant in the feed pipe to preheat the oxidant so that the combustion temperature is higher than the adiabatic flame temperature, achieving a super-adiabatic combustion state. The higher combustion temperature can replace the role of the catalyst and accelerate the gasification and cracking of solid fuel. Since the combustion temperature is between 700-900℃, the formation of NOx can be largely avoided.

[0054] This invention can be used in mixed combustion processes and operating conditions. After the oxidant enters the reactor, it undergoes a gasification and cracking reaction with solid fuel particles to produce carbon monoxide. The combustion zone is in the central region. The heat generated is used to gasify and crack the solid fuel in the mixture above the flame through radiation and heat conduction. The moving grid module makes the reactor move in an orderly manner in the direction of flame movement, simulating the feeding and discharging process through relative motion. At the same time, the radiation and convection heat transfer of the flame transfers excess heat to the inert porous medium, and with the discharge, heat is transferred to the oxidant in the feed pipe to preheat the oxidant so that the combustion temperature is higher than the adiabatic flame temperature, achieving a super-adiabatic combustion state. The higher combustion temperature can replace the role of the catalyst and accelerate the gasification and cracking of solid fuel. Since the combustion temperature is between 700-900℃, the formation of NOx can be largely avoided, realizing the simulation of continuous operation in industry.

[0055] Example 1:

[0056] The embodiments of the present invention provide further explanation of the algorithm structure and specific simulation process of a one-dimensional simulation device for a solid fuel moving bed filtration combustion gasification pyrolysis process. Those skilled in the art should understand that the following specific description is illustrative and not restrictive, and should not be used to limit the scope of protection of the present invention.

[0057] The one-dimensional simulation device for a solid fuel moving bed filtration combustion gasification and pyrolysis process in this embodiment 1 is applied in the following manner:

[0058] First, the user inputs the initial values ​​required for the simulation into the experimental parameter module, calculation parameter module, reaction mechanism module, and boundary condition module in the input module. The experimental module includes the mixing ratio of fuel and inert porous media, the type of inert porous media, oxidant volumetric flow rate, fuel density, reactor length, inert media particle size, mixed porosity of fuel and inert porous media, charge height, solid-phase thermal conductivity, and gas-phase thermal conductivity. The calculation module includes the number of grids, the total number of calculation time steps, the time interval between output files, the time interval between output graphs, the number of iterations per time step, the convergence residual for each time step, and the file name of the output data. The reaction mechanism module includes the pre-exponential factor, activation energy, and temperature exponent for homogeneous and heterogeneous chemical reaction mechanisms. The boundary condition module includes the initial flow field temperature, ignition zone temperature, and ignition zone width percentage. After these required parameters are input, the array module stores the data for each variable according to the length of the parameters input by the user in the input module. The initialization module uses the parameters input from the input module to initialize the flow field and assign values ​​accordingly. The temperature values ​​are converted to Kelvin, and the specific surface area of ​​the porous medium is calculated for simulation. An initial temperature value is assigned to the ignition zone. After ignition, the flame begins to propagate from the bottom of the reactor upstream. When the flame reaches the middle of the reactor, the bottom of the reactor begins to feed and discharge materials in an orderly manner. To simulate this process, the moving grid module moves the reactor in an orderly manner in the direction of flame movement, simulating the feeding and discharging process through relative motion. The graph output module outputs the simulated calculation values ​​after each time step, including the solid and gas temperatures and the concentrations of CO, CO2, and O2 components for each grid. The calculation is performed in multiple time steps, and the device equations are iteratively calculated within each time step. The iteration method uses the core calculation module, so the module outputs the graphs after the calculation reaches the user-defined time interval. The device equations include gas phase energy equations, solid phase energy equations, mass equations, and component transport equations. It is assumed that the gas flow rate is constant, so there is no momentum equation. All equations are solved transiently using the Newton-Raphson iteration method.

[0059] It should be noted that in the above embodiments, as long as the technical solutions are not contradictory, they can be permuted and combined. Those skilled in the art can exhaust all possibilities based on the mathematical knowledge of permutation and combination. Therefore, the present invention will not describe the technical solutions after permutation and combination one by one, but it should be understood that the technical solutions after permutation and combination have been disclosed by the present invention.

[0060] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A one-dimensional simulation device for a solid fuel moving bed filtration combustion gasification pyrolysis process, characterized in that: include: Input module: Reads user-defined initial flow field values, including initial temperature, initial velocity, initial fuel blending ratio, and reaction mechanism-related parameters; Array setting module: Based on the length of the parameters input by the user in the input module, it is used to store the data of each variable; Initialization module: Use the initialization module to initialize the flow field; initialization includes assigning values ​​to the initial state of the flow field; Moving grid module: As the flame spreads from the bottom to the middle of the reactor, the bottom of the reactor begins to feed and discharge materials in an orderly manner; the moving grid module enables the reactor to move in an orderly manner to simulate the feeding and discharging process; The moving grid module is initially off by default. When the flame propagates from the bottom to the middle of the reactor, half the length of the reactor is divided by the time it takes for the flame to propagate from the bottom to the middle to obtain the flame propagation speed. Then, continuous feeding begins at the bottom of the reactor, with the feeding speed matching the flame propagation speed. Orderly discharge also begins at the bottom of the reactor, with the discharge speed matching the flame propagation speed. This stabilizes the flame in the middle region of the reactor, achieving a stable operating state. At time T, the flame propagates to the middle of the reactor. At time T+Δt, the flame propagates to the next grid. At this point, the moving grid module adds a grid to the right end of the reactor, with internal parameters consistent with the initial parameters. Simultaneously, a grid is removed from the left end of the reactor, ensuring the flame remains in the middle position of the reactor. This simulation of the feeding and discharging process is achieved through the relative movement of the grids. Core computing module: The calculation is performed in multiple time steps, and the device equations are calculated iteratively within each time step; Chart Output Module: After the calculation is completed, use the chart output module to output the simulation calculation values, including the temperature, CO, CO2, and O2 component concentrations of each grid.

2. The one-dimensional simulation device for the solid fuel moving bed filtration combustion gasification pyrolysis process according to claim 1, characterized in that: The input module includes: Experimental parameter module: Inputs include the mixing ratio of fuel and inert porous media, the type of inert porous media, the volumetric flow rate of oxidant, fuel density, reactor length, particle size of inert media, mixed porosity of fuel and inert porous media, charging height, solid phase thermal conductivity and gas phase thermal conductivity. The calculation parameters module includes the following inputs: number of grids, total number of calculation time steps, time interval of output files, time interval of output graphs, number of iterations per time step, convergence residuals per time step, residuals per time step, and file name of the output data. Reaction Mechanism Module: Includes homogeneous chemical reaction mechanisms and heterogeneous chemical reaction mechanisms. The reaction mechanism adopts a four-step reaction mechanism, as follows: The input mechanistic parameters include pre-exponential factor, activation energy, and temperature exponent; Boundary Conditions Module: Inputs include initial flow field temperature, ignition zone temperature, and ignition zone width percentage.

3. The one-dimensional simulation device for the solid fuel moving bed filtration combustion gasification pyrolysis process according to claim 2, characterized in that: Initialization module: This module initializes the flow field using parameters input from the input module, converts temperature values ​​to Kelvin, and calculates the specific surface area SA of the porous medium. It's porosity. d p This refers to the characteristic diameter of inert porous media, used for simulation calculations; 。 4. The one-dimensional simulation device for the solid fuel moving bed filtration combustion gasification pyrolysis process according to claim 3, characterized in that: The chart output module outputs simulated values ​​after the calculation is completed, including the temperature of solids and gases, and the concentrations of CO, CO2, and O2 components for each grid. The calculation is divided into multiple time steps, and the device equations are iteratively calculated within each time step. The iteration method uses the core calculation module for calculation. Therefore, after the calculation reaches the time interval defined by the user for outputting the chart, the module will be used to output the chart.

5. The one-dimensional simulation device for the solid fuel moving bed filtration combustion gasification pyrolysis process according to claim 4, characterized in that: The core calculation module iteratively solves the equations for the entire device, assuming that the fuel particles are non-volatile, water-free, have a constant particle size during combustion, and leave no component residue after combustion; the oxidant is an incompressible ideal gas, the solid fuel particles and inert medium particles are uniformly mixed, and the gas flow rate in the reactor remains constant; the device equations include gas phase energy equations, solid phase energy equations, mass equations, and component transport equations; all equations are iterated using the Newton-Raphson iteration method for transient solutions.

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