Waste heat recovery boiler analysis method and system for impurity particle-containing tail gas in smelting industry

Abstract

The invention belongs to the technical field of boiler modeling and numerical calculation, and relates to a waste heat recovery boiler analysis method and system for impurity particle-containing tail gas in the smelting industry. The method comprises the following steps: collecting impurity particle-containing tail gas in the smelting industry, and measuring to obtain experimental data; performing grid division on the three-dimensional geometric model to obtain a grid model; setting parameters of a fluid phase and a particle phase in the boiler according to experimental data; performing numerical simulation calculation on the grid model to obtain a temperature field, a pressure field, a component field, a velocity field and a particle trajectory; performing data post-processing to obtain a data post-processing result; and adjusting the structural parameters of the waste heat recovery boiler according to the data post-processing result, and repeating the structural optimization design of the smelting industry impurity particle-containing tail gas waste heat recovery boiler until the parameters in the post-processing result meet the preset requirements. The problem that an existing numerical simulation calculation method is not suitable for a waste heat recovery boiler for smelting industrial tail gas containing impurity particles is solved.

Description

Technical Field

[0001] The present invention belongs to the technical field of boiler modeling and numerical calculation, and in particular relates to a waste heat recovery boiler analysis method and system for tail gas containing impurity particles in a smelting industry. Background Art

[0002] As the world's development continues to increase the demand for various metal and non-metal smelting products, the scale of the smelting industry is also expanding year by year. Whether it is metal or non-metal smelting, a large amount of high-temperature or combustible component-rich tail gas will be generated during the smelting process. For example, a large amount of high-temperature tail gas above 1100°C will be generated during the copper smelting process, and the production of one ton of yellow phosphorus will produce 2500 to 3000 standard cubic meters of high calorific value tail gas containing 90% CO. With the introduction and upgrading of relevant policies on the energy or resource utilization of tail gas in the smelting industry, the demand for waste heat recovery boilers for smelting industry tail gas has increased rapidly. However, the current waste heat recovery boilers often have problems such as unreasonable flow field organization and lack of theoretical basis for related designs. In addition, the tail gas of the smelting industry often contains a large amount of high-temperature oxide slag or corrosive impurity particles, resulting in a short service life of most waste heat recovery boilers for smelting industry tail gas and a lack of safety guarantee. The energy or resource utilization of tail gas in the smelting industry has become a major problem in the development of the smelting industry.

[0003] Previously, the performance evaluation of waste heat recovery boilers in the smelting industry was mainly carried out through experimental means, and its design basis basically came from the production experience of practitioners. Therefore, there were problems such as long cycle, high cost, lack of system specifications, and unclear influence of impurity particles, which made it difficult to form a set of methodologies for performance evaluation and structural optimization design of waste heat recovery boilers in the smelting industry.

[0004] At present, numerical simulation calculation method is one of the most important tools in the process of large-scale equipment performance evaluation and structural optimization design. Through fine modeling, selection of reasonable sub-models, and accurate definition of parameters, quite accurate prediction data can be obtained, and numerical simulation calculation method also has the advantages of low cost and high efficiency. However, after searching, no relevant numerical simulation analysis method for waste heat recovery boiler of tail gas containing impurities in smelting industry has been reported. Summary of the invention

[0005] The purpose of the present invention is to provide a waste heat recovery boiler analysis method and system for tail gas containing impurity particles in the smelting industry, which solves the problem that the existing numerical simulation calculation method is not suitable for waste heat recovery boilers for tail gas containing impurity particles in the smelting industry.

[0006] The present invention is achieved through the following technical solutions:

[0007] The present invention discloses a waste heat recovery boiler analysis method for tail gas containing impurity particles in smelting industry, comprising the following steps:

[0008] S1. Collect tail gas containing impurity particles from the smelting industry, separate the gas from the impurity particles after cooling, and obtain experimental data after measurement;

[0009] The experimental data include the composition and proportion of gas components in the exhaust gas, the particle size distribution and true density of impurity particles in the exhaust gas;

[0010] S2. Constructing a three-dimensional geometric model of a waste heat recovery boiler for treating tail gas containing impurities and particles in the smelting industry;

[0011] S3, meshing the three-dimensional geometric model to obtain a mesh model;

[0012] S4. Setting boundary conditions that meet the actual operation conditions based on the grid model;

[0013] Set the parameters of the fluid phase and particle phase inside the boiler according to the experimental data obtained in S1;

[0014] According to the actual operation of the waste heat recovery boiler, the calculation model, discrete format, numerical solution method and relaxation factor are set for the numerical simulation;

[0015] S5, performing numerical simulation calculation on the grid model, first initializing the numerical simulation calculation domain and starting to solve, and obtaining the temperature field, pressure field, component field, velocity field and particle trajectory;

[0016] S6, performing data post-processing on the temperature field, pressure field, component field, velocity field and particle trajectory to obtain data post-processing results;

[0017] S7. Adjust the structural parameters of the waste heat recovery boiler according to the data post-processing results, and repeat S2-S6 to perform the structural optimization design of the waste heat recovery boiler for tail gas containing impurities in the smelting industry until the parameters in the post-processing results in S6 meet the preset requirements.

[0018] Further, in S1, a sealed air bag is used to collect the tail gas containing impurities and particles in the smelting industry in the actual industrial process;

[0019] If the exhaust gas temperature is higher than the operating temperature of the sealed air bag, the exhaust gas is pre-cooled before collection. During the collection process, it is ensured that there is no leakage of the exhaust gas. The collected exhaust gas has the same composition as the actual exhaust gas, which is used to ensure the accuracy of subsequent analysis.

[0020] In S1, after the tail gas containing impurity particles in the smelting industry is cooled to room temperature, the gas and the impurity particles are separated, and the composition and proportion of the gas components in the tail gas are measured by gas chromatography, and the particle size distribution and true density of the impurity particles in the tail gas are measured by Malvern spray particle size analyzer and true density tester.

[0021] Furthermore, S2 is specifically as follows: based on the drawing parameters of the waste heat recovery boiler actually used to treat the tail gas containing impurity particles in the smelting industry, the fluid domain of the waste heat recovery boiler is modeled at a 1:1 three-dimensional geometry using Solidworks software, and the three-dimensional geometric model of the waste heat recovery boiler is named the computational domain using the DesignModeler module in the Workbench platform of Ansys software.

[0022] Furthermore, S3 is specifically as follows: meshing the three-dimensional geometric model with a hexahedral mesh, meshing the waste heat recovery boiler wall, swirl burner blades, and impurity particle capture component area to obtain a mesh model, and performing a mesh quality check after meshing is completed.

[0023] Further, in S3, the fluid phase and particle phase parameters inside the boiler are set according to the experimental data of the tail gas containing impurities and particles in the smelting industry, specifically:

[0024] According to the composition and proportion of the gas components in the tail gas obtained by S1, the components of the mixed fluid phase inside the boiler are set. The thermal properties of the mixed fluid phase are calculated according to the component ratio, and the radiation characteristics select the wsggm-domain-based model; CO and CH 4 The combustion reaction;

[0025] According to the particle size distribution and true density of impurity particles in the tail gas obtained by S1, the particle size distribution and true density of the particle phase inside the boiler are set;

[0026] If the impurity particle content in the exhaust gas is less than 10%, the interaction between particles is ignored and the DPM discrete phase model is selected; if the impurity particle content is greater than 10%, the interaction between particles is considered and the DDPM discrete phase model is selected. In the discrete model, particles are injected from the boiler inlet in the form of surface injection, and the injection speed is consistent with the fluid phase.

[0027] Further, in S4, the boundary conditions include inlet boundary conditions, outlet boundary conditions and wall boundary conditions;

[0028] Inlet boundary conditions include velocity, temperature, turbulence intensity, and component ratio;

[0029] The outlet boundary conditions include pressure, flow rate ratio, and escape of impurity particles;

[0030] The wall boundary conditions need to be set to isothermal / adiabatic, with / without slip, and impurity particles being captured / rebounded according to actual conditions.

[0031] Further, in S4, the computational model includes a turbulence model, a radiation model, a gas phase chemical reaction model, a discrete phase model and a drag model;

[0032] The turbulence model selected is the Realizable k-ε model for medium swirl intensity;

[0033] Select DO model for radiation model;

[0034] The gas phase chemical reaction model is selected to deal with the finite rate / eddy dissipation combustion model of partially premixed flame and turbulence;

[0035] The discrete phase model is selected between the DPM model and the DDPM model according to the actual situation;

[0036] The drag model selects the Wen-Yu drag model, which is used to calculate the interaction force between the discrete phase and the fluid phase;

[0037] In S4, the pressure term in the discrete format uses the Standard discrete format, and other terms use the second-order upwind format; other terms include components, velocity, and temperature;

[0038] The Phase coupled SIMPLE algorithm was selected as the numerical solution method;

[0039] The pressure relaxation factor was set to 0.2, the component-related relaxation factor was set to 1, and the relaxation factors of other items were set to 0.4.

[0040] Further, in S6, the data post-processing is specifically as follows:

[0041] Post-process the temperature field to obtain the average temperature of the boiler flue gas outlet and the uniformity of the temperature distribution in the furnace;

[0042] Post-process the pressure field to obtain the overall and local pressure drops;

[0043] Post-process the component field to obtain the burnout rate of the combustible component;

[0044] Post-process the velocity field to obtain the volume of the boiler recirculation area, the temperature and velocity of the air flow near the water-cooled wall;

[0045] Post-process the particle trajectory to obtain the furnace outlet escape rate, water-cooled wall adhesion rate, and capture rate of the filter capture component of the impurity particles;

[0046] The thermal performance of the boiler is evaluated by the average temperature of the boiler flue gas outlet, the burnout rate of the combustible components and the uniformity of the temperature distribution in the furnace;

[0047] The boiler flow field organization performance is evaluated based on the boiler recirculation area volume, air flow temperature and velocity near the water-cooled wall, and overall and local pressure drops;

[0048] The degree to which the boiler is affected by corrosion or wear of impurity particles in the exhaust gas is evaluated based on the escape rate of the furnace outlet, the adhesion rate of the water-cooled wall, and the capture rate of the filtering and capturing components.

[0049] Furthermore, in S7, the structural parameters of the waste heat recovery boiler include the air distribution of the burner, the size of the furnace, and the position and size of the impurity particle filtering and capturing component.

[0050] The present invention also discloses a waste heat recovery boiler analysis system for tail gas containing impurities and particles in the smelting industry, comprising:

[0051] A data acquisition module is used to acquire experimental data; the experimental data includes the composition and proportion of gas components in the exhaust gas, and the particle size distribution and true density of impurity particles in the exhaust gas;

[0052] A construction module for constructing a three-dimensional geometric model of a waste heat recovery boiler for treating tail gas containing impurities and particles in the smelting industry;

[0053] A meshing module is used to mesh the three-dimensional geometric model to obtain a mesh model;

[0054] The condition setting module is used to set boundary conditions that meet the actual operation conditions based on the grid model;

[0055] Set the fluid phase and particle phase parameters inside the boiler according to experimental data;

[0056] According to the actual operation of the waste heat recovery boiler, the calculation model, discrete format, numerical solution method and relaxation factor are set for the numerical simulation;

[0057] The simulation module is used to perform numerical simulation calculations on the grid model. First, the numerical simulation calculation domain is initialized and the solution is started to obtain the temperature field, pressure field, component field, velocity field and particle trajectory;

[0058] The data post-processing module is used to perform data post-processing on the temperature field, pressure field, component field, velocity field and particle trajectory to obtain the data post-processing results;

[0059] The structural adjustment and optimization module is used to adjust the structural parameters of the waste heat recovery boiler according to the data post-processing results, and repeatedly perform the structural optimization design of the waste heat recovery boiler for tail gas containing impurities in the smelting industry until the parameters in the post-processing results meet the preset requirements.

[0060] Compared with the prior art, the present invention has the following beneficial technical effects:

[0061] The present invention discloses a performance evaluation and analysis method for a waste heat recovery boiler of tail gas containing impurity particles in a smelting industry based on numerical simulation. Firstly, the real information of the tail gas containing impurity particles in the smelting industry is obtained through field collection and experimental characterization. Then, a numerical calculation model of the tail gas waste heat recovery boiler is constructed through fine geometric modeling, reasonable grid division, suitable boundary conditions, and the setting of internal phase parameters and calculation sub-models. The numerical calculation model is placed in a real operating state of the boiler, and numerical simulation calculation is performed. The internal temperature field, velocity field, pressure field, particle trajectory and other information of the boiler can be effectively simulated and visualized, thereby effectively evaluating the thermal performance, flow field organization performance, and the degree of influence of corrosion or wear by impurity particles of the boiler, and the reliability of the evaluation result is strong.

[0062] The method is based on the numerical simulation results of the prototype of the waste heat recovery boiler for tail gas containing impurity particles in the smelting industry, with the optimization goals of improving the thermal performance of the boiler, optimizing the boiler flow field organization performance, reducing the furnace outlet escape rate and water-cooled wall adhesion rate of the impurity particles in the tail gas, and increasing the capture rate of the impurity particles in the tail gas by the filtering and capturing components in the boiler. By using the above-mentioned numerical simulation calculation method, the boiler is effectively structurally optimized by adjusting the burner air distribution, furnace size, position and size of the impurity particle filtering and capturing components and other structural parameters. The structural optimization method has low cost, high efficiency and strong reliability.

[0063] This method has been proven to be applicable to the performance evaluation and structural optimization of different types of waste heat recovery boilers used in smelting industry tail gas containing impurities and particles from different sources, and has a certain degree of universality. BRIEF DESCRIPTION OF THE DRAWINGS

[0064] Figure 1 It is a flow chart of a method for analyzing a waste heat recovery boiler of tail gas containing impurity particles in a smelting industry based on numerical simulation according to the present invention;

[0065] Figure 2 : is the particle size distribution of impurity particles in the smelting industry tail gas in the embodiment of the present invention. DETAILED DESCRIPTION

[0066] In order to make the purpose, technical solution and advantages of the present invention more clear, the following is further described in detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention, that is, the embodiments described are only part of the embodiments of the present invention, not all embodiments.

[0067] The components described and shown in the drawings and embodiments of the present invention may be arranged and designed in various configurations. Therefore, the detailed description of the embodiments of the present invention provided in the following drawings is not intended to limit the scope of the claimed invention, but merely represents a selected embodiment of the present invention. Based on the drawings and embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0068] It should be noted that the terms "comprises", "includes" or any other variations are intended to cover non-exclusive inclusion, so that a process, element, method, article or equipment that includes a series of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements inherent to the process, element, method, article or equipment.

[0069] Example 1

[0070] The present invention discloses a waste heat recovery boiler analysis method for tail gas containing impurity particles in smelting industry, comprising the following steps:

[0071] S1. Collect tail gas containing impurity particles from the smelting industry, separate the gas from the impurity particles after cooling, and obtain experimental data after measurement;

[0072] The experimental data include the composition and proportion of gas components in the exhaust gas, the particle size distribution and true density of impurity particles in the exhaust gas;

[0073] S2. Constructing a three-dimensional geometric model of a waste heat recovery boiler for treating tail gas containing impurities and particles in the smelting industry;

[0074] S3, meshing the three-dimensional geometric model to obtain a mesh model;

[0075] S4. Setting boundary conditions that meet the actual operation conditions based on the grid model;

[0076] Set the parameters of the fluid phase and particle phase inside the boiler according to the experimental data obtained in S1;

[0077] According to the actual operation of the waste heat recovery boiler, the calculation model, discrete format, numerical solution method and relaxation factor are set for the numerical simulation;

[0078] S5, performing numerical simulation calculation on the grid model, first initializing the numerical simulation calculation domain and starting to solve, and obtaining the temperature field, pressure field, component field, velocity field and particle trajectory;

[0079] S6, performing data post-processing on the temperature field, pressure field, component field, velocity field and particle trajectory to obtain data post-processing results;

[0080] S7. Adjust the structural parameters of the waste heat recovery boiler according to the data post-processing results, and repeat S2-S6 to perform the structural optimization design of the waste heat recovery boiler for tail gas containing impurities in the smelting industry until the parameters in the post-processing results in S6 meet the preset requirements.

[0081] Example 2

[0082] This paper mainly introduces the measurement process of experimental data.

[0083] In S1, sealed air bags are used to collect the corresponding smelting industry tail gas containing impurity particles in the actual industrial process; the tail gas is collected at the end of the actual smelting industrial process. If the tail gas temperature is higher than the operating temperature of the sealed air bag, it should be pre-cooled before collection. During the collection process, it should be ensured that there is no leakage of the tail gas, and the collected tail gas has the same composition as the actual tail gas to ensure the accuracy of the analysis method.

[0084] After the smelting industry tail gas containing impurity particles is allowed to stand and cool to room temperature, the gas is separated from the impurity particles, and the gas component composition and proportion in the tail gas are measured using gas chromatography. The particle size distribution and true density of the impurity particles in the tail gas are measured using a Malvern spray particle size analyzer and a true density tester. The characterization process should be carried out strictly in accordance with the instrument operating specifications to ensure that the tail gas components and impurity particle parameters in subsequent numerical simulations are consistent with the actual situation, thereby improving the reliability of the analysis method.

[0085] S2 is specifically: based on the drawing parameters of the waste heat recovery boiler actually used to treat the tail gas containing impurities and particles in the smelting industry, the fluid domain of the waste heat recovery boiler is modeled at a 1:1 three-dimensional geometry using Solidworks software, and the three-dimensional geometric model of the waste heat recovery boiler is named in the calculation domain using the DesignModeler module in the Workbench platform of Ansys software.

[0086] Example 3

[0087] This paper mainly introduces the meshing process of the model.

[0088] In S3, the three-dimensional geometric model of the waste heat recovery boiler for exhaust gas containing impurity particles in the smelting industry is meshed to obtain a mesh model of the boiler; specifically: the three-dimensional geometric model of the waste heat recovery boiler for exhaust gas containing impurity particles in the smelting industry is meshed using hexahedral meshes, and the important areas such as the boiler wall, swirl burner blades, and impurity particle capture components are appropriately meshed to obtain the mesh model of the boiler, and a mesh quality check is performed after the meshing is completed.

[0089] In order to reduce the computational cost while ensuring the accuracy of numerical simulation, a grid independence test should be performed on the grid model to determine the appropriate grid partitioning parameters and the number of grid cells.

[0090] Example 4

[0091] It mainly introduces the relevant processes of numerical simulation.

[0092] In S3, the fluid phase and particle phase parameters inside the boiler are set according to the experimental data of the impurity particle tail gas in the smelting industry, including the composition of the fluid and the chemical reactions involved, and the particle size distribution and true density of the particle phase; specifically:

[0093] The composition of the mixed fluid phase inside the boiler is set according to the gas chromatography measurement data of the impurity particle tail gas of the smelting industry. Common smelting industry tail gas contains CO, CH 4 , CO 2 , O 2 、N 2 However, the proportion of components in tail gas from different smelting industries is different. The thermal properties of the mixed fluid phase are calculated according to the proportion of components. The radiation characteristics select the wsggm-domain-based model. The internal operation of the waste heat recovery boiler of the tail gas containing impurities in the smelting industry needs to consider CO and CH 4 The combustion reaction:

[0094] CO + 0.5O 2 →CO 2 (A=7.9799E+14, Ea=96.54kJ / mol)

[0095] CH 4 +1.5O 2 →CO+2H 2 O(A=1.6596E+15, Ea=172kJ / mol).

[0096] According to the measurement data of Malvern spray particle size analyzer and true density tester of the tail gas containing impurity particles in the smelting industry, the particle size distribution and true density of the particle phase inside the boiler are set. If the impurity particle content in the tail gas is less than 10%, the interaction between the particles can be ignored, and the DPM discrete phase model is selected. If the impurity particle content is greater than 10%, the interaction between the particles should be considered, and the DDPM discrete phase model is selected. In the discrete model, the particles are sprayed from the boiler inlet in the form of surface injection, and the injection speed is consistent with the fluid phase.

[0097] In S4, boundary conditions that meet the actual operating conditions are set based on the grid model of the waste heat recovery boiler for tail gas containing impurity particles in the smelting industry. The inlet boundary conditions need to set the velocity, temperature, turbulence intensity, and component ratio. The outlet boundary conditions need to set the pressure, flow ratio, and impurity particle escape. The wall boundary conditions need to be set to isothermal / adiabatic, with / without slip, and impurity particles being captured / rebounded based on the actual situation.

[0098] According to the actual operation of the waste heat recovery boiler of the tail gas containing impurities in the smelting industry, a reasonable calculation model, discrete format, solution method and relaxation factor are set for numerical simulation; specifically, the calculation model includes a turbulence model, a radiation model, a gas phase chemical reaction model, a discrete phase model and a drag model;

[0099] The turbulence model selected is the Realizable k-ε model for medium swirl intensity;

[0100] Select DO model for radiation model;

[0101] The gas phase chemical reaction model is selected to deal with the finite rate / eddy dissipation combustion model of partially premixed flame and turbulence;

[0102] The discrete phase model is selected between the DPM model and the DDPM model according to the actual situation;

[0103] The drag model selects the Wen-Yu drag model to calculate the interaction force between the discrete phase and the fluid phase.

[0104] According to the actual operation of the waste heat recovery boiler for tail gas containing impurities and particles in the smelting industry, a reasonable discrete format, solution method and relaxation factor are set for the numerical simulation. The pressure term in the discrete format adopts the Standard discrete format, and the other terms adopt the second-order upwind format. The other terms include component, velocity and temperature. The Phase coupled SIMPLE algorithm is selected as the numerical solution method, the pressure relaxation factor is set to 0.2, the component-related relaxation factor is set to 1, and the relaxation factors of other terms are set to 0.4.

[0105] In S5, the numerical simulation calculation domain of the waste heat recovery boiler for the tail gas containing impurities and particles in the smelting industry is initialized according to the inlet boundary conditions, and then the boiler is ignited in the form of a Patch high-temperature cover in the area near the inlet, and the iterative steady-state solution is started in Fluent until the residual curves of each calculated quantity tend to be stable and then stop.

[0106] Example 5

[0107] In S6, data post-processing is performed on the thermal performance, flow field distribution, capture or escape of impurity particles, etc. of the waste heat recovery boiler for tail gas containing impurity particles in the smelting industry; the data post-processing is specifically as follows:

[0108] Post-process the temperature field to obtain the average temperature of the boiler flue gas outlet and the uniformity of the temperature distribution in the furnace;

[0109] Post-process the pressure field to obtain the overall and local pressure drops;

[0110] Post-process the component field to obtain the burnout rate of the combustible component;

[0111] Post-process the velocity field to obtain the volume of the boiler recirculation area, the temperature and velocity of the air flow near the water-cooled wall;

[0112] The particle trajectory is post-processed to obtain the furnace outlet escape rate of impurity particles, the water-cooled wall adhesion rate, and the capture rate of the filtering and capturing components.

[0113] The steady-state solution results of the waste heat recovery boiler for tail gas containing impurity particles in the smelting industry are post-processed using tecplot software, and the thermal performance of the boiler is evaluated based on parameters such as the average temperature of the boiler flue gas outlet, the burnout rate of combustible components, and the uniformity of temperature distribution in the furnace. The volume of the boiler recirculation zone, the air flow temperature and velocity near the water-cooled wall, and the overall and local pressure drops are used to evaluate the boiler flow field organization performance. The furnace outlet escape rate of impurity particles in the tail gas, the water-cooled wall attachment rate, and the capture rate of the filtering and capturing components are used to evaluate the degree of influence of corrosion or wear of impurity particles on the boiler.

[0114] According to the post-treatment performance evaluation results of the waste heat recovery boiler for exhaust gas containing impurities and particles in the smelting industry, the burner air supply, furnace size, impurity particle filtering and capturing component position and size and other structural parameters of the boiler are appropriately adjusted, and the numerical simulation calculation steps are repeated to perform structural optimization of the waste heat recovery boiler for exhaust gas containing impurities and particles in the smelting industry.

[0115] Different types of waste heat recovery boilers used with smelting industry tail gas containing impurities and particles from different sources can be studied using the waste heat recovery boiler analysis method for smelting industry tail gas containing impurities and particles based on numerical simulation, which has a certain degree of universality.

[0116] Example 6

[0117] The present invention also discloses a waste heat recovery boiler analysis system for tail gas containing impurities and particles in the smelting industry, comprising:

[0118] A data acquisition module is used to acquire experimental data; the experimental data includes the composition and proportion of gas components in the exhaust gas, and the particle size distribution and true density of impurity particles in the exhaust gas;

[0119] A construction module for constructing a three-dimensional geometric model of a waste heat recovery boiler for treating tail gas containing impurities and particles in the smelting industry;

[0120] A meshing module is used to mesh the three-dimensional geometric model to obtain a mesh model;

[0121] The condition setting module is used to set boundary conditions and internal phase parameters that meet the actual operating conditions based on the grid model;

[0122] According to the actual operation of the waste heat recovery boiler, the calculation model, discrete format, numerical solution method and relaxation factor are set for the numerical simulation;

[0123] The simulation module is used to perform numerical simulation calculations on the grid model. First, the numerical simulation calculation domain is initialized and the solution is started to obtain the temperature field, pressure field, component field, velocity field and particle trajectory;

[0124] The data post-processing module is used to perform data post-processing on the temperature field, pressure field, component field, velocity field and particle trajectory to obtain the data post-processing results;

[0125] The structural adjustment and optimization module is used to adjust the structural parameters of the waste heat recovery boiler according to the data post-processing results, and repeatedly perform the structural optimization design of the waste heat recovery boiler for tail gas containing impurities in the smelting industry until the parameters in the post-processing results meet the preset requirements.

[0126] The features and performances of the present invention are further described in detail below in conjunction with actual verification examples.

[0127] Reference Figure 1 As shown, this embodiment provides a method for analyzing a waste heat recovery boiler of tail gas containing impurities and particles in a smelting industry based on numerical simulation. This embodiment performs performance evaluation and structural optimization on a yellow phosphorus smelting tail gas waste heat recovery boiler of model SZS25-2.5 / 400-HLQ designed and produced by a boiler factory, specifically including the following steps:

[0128] Step 1: Use sealed air bags to collect tail gas at the end of the yellow phosphorus smelting process. After the inherent gas washing treatment, the temperature of the yellow phosphorus smelting tail gas is lower than the upper limit of the use temperature of the sealed air bag, so no additional cooling treatment is required.

[0129] Step 2: After the collected tail gas is cooled to room temperature, the gas is separated from the impurity particles. The gas components in the tail gas are measured by gas chromatography and include 92.47% CO, 2.03% CH 4 3.76% CO 2 0.43%O 2 、1.31%N 2The particle size distribution of impurity particles in the exhaust gas was measured using a Malvern spray particle size analyzer. Figure 2 As shown in the figure, the real density of impurity particles in the exhaust gas measured by the true density tester is 1828kg / m 3 ,All experimental measurements were carried out strictly in accordance with the instrument operation specifications.

[0130] Step 3. Based on the drawings and parameters of the SZS25-2.5 / 400-HLQ yellow phosphorus smelting tail gas waste heat recovery boiler provided by a boiler factory, first use Solidworks software to perform 1:1 three-dimensional geometric modeling of the fluid domain of the boiler. Based on the principle of confidentiality, the schematic diagram of the geometric model of the boiler is not displayed. The geometric model includes a swirl burner, a three-stage furnace, and an impurity particle filtering and capturing component in the furnace. Then, the DesignModeler module is used in the Workbench platform of Ansys software to name the computational domain of the three-dimensional geometric model of the boiler.

[0131] Step 4: Use hexahedral meshes to mesh the three-dimensional geometric model of the boiler, appropriately encrypt the meshes of important areas such as the boiler wall, swirl burner blades, and impurity particle filtering and capturing components to obtain a mesh model of the boiler, and perform a mesh quality check after meshing to ensure that the mesh quality is above 0.6.

[0132] Step 5. Perform a grid independence test on the grid model. Use different grid division parameters to divide the grid models with 208984, 472816, 836870, 1330849, and 1916490 grid units. After numerical simulation, select the burner and the center axis of the furnace as the characteristic line, and use the axial velocity, temperature, and CO component content as characteristic quantities for testing. Analysis shows that the difference between the results of 1330849 units and 1916490 units is negligible. Therefore, in order to ensure the accuracy of numerical simulation while reducing the calculation cost, select the parameters of 1330849 units for grid division in subsequent steps.

[0133] Step 6: Set the composition of the mixed fluid phase inside the boiler to CO, CH 4 , CO 2 , O 2 、N 2 , the excess air coefficient is set to 1.1, the thermal properties of the mixed fluid phase are calculated according to the component ratio, the radiation characteristics select the wsggm-domain-based model, and consider the CO and CH 4 combustion reaction.

[0134] Step 7: Set the particle size distribution and true density of the particle phase inside the boiler according to the measured values ​​in step 2. Since the content of impurity particles in the tail gas is less than 10%, the interaction between particles can be ignored. Select the DPM discrete phase model. The particles are injected from the tail gas inlet of the boiler in the form of surface injection. The injection speed is consistent with the fluid phase. According to the boiler 6648.4Nm 3 The exhaust gas treatment capacity / h and the exhaust gas inlet size are calculated to obtain an injection velocity of 13.20787 m / s. The particle mass flow rate is calculated based on the mass of impurity particles in the collected exhaust gas to be 3.694×10 -4 kg / s.

[0135] Step 8. On the basis of the grid model, boundary conditions that meet the actual operating conditions are set. The inlet boundaries are divided into the central air, primary air, and secondary air inlets of the burner. The inlet velocities and component ratios are set according to the air distribution conditions. The temperatures of each inlet boundary are room temperature and the turbulence intensity is 5%; the outlet boundary is the furnace outlet, with a relative pressure of 0 and a flow rate ratio of 1, from which impurity particles escape; the wall boundaries include the burner wall and blades, the furnace wall and water-cooled wall, and the surface of the impurity particle filtering and capturing component. Except for the water-cooled wall which is set as an isothermal boundary, the rest are adiabatic boundaries, and all walls are no-slip walls. Impurity particles are set to rebound on the burner wall and blades and will be captured by the other walls.

[0136] Step nine, according to the actual operation of the boiler, set a reasonable calculation sub-model for numerical simulation, select the Realizable□-□ model that can be applied to medium swirl intensity as the turbulence model, select the DO model as the radiation model, select the finite rate / eddy dissipation combustion model that can handle partially premixed flames and turbulence as the gas phase chemical reaction model, select the DPM model as the discrete phase model, and select the wen-yu drag model for calculation of the interaction force between the discrete phase and the fluid phase.

[0137] Step 10. Set the discrete format of pressure in the simulation calculation to Standard, use the second-order upwind format for other items, select the Phase coupled SIMPLE algorithm for the numerical solution method, set the relaxation factors of pressure and component to 0.2 and 1 respectively, and set the relaxation factors of other items to 0.4.

[0138] Step 11: Initialize the computational domain of the boiler according to the boundary conditions of the central air inlet, and then set a high temperature cover of 1000°C (higher than the ignition point of CO) in the form of a patch in the area near the furnace inlet to complete the ignition. Start iterative steady-state solution in Fluent, which takes about 5000 iterations until the residual curves of each calculated quantity tend to be stable.

[0139] Step 12: The calculation results of the steady-state solution are post-processed using tecplot software. The average temperature of the boiler flue gas outlet is 1049.6°C, the unburned rate of combustible components is 1.91%, and the temperature distribution uniformity in the furnace is poor. Therefore, the thermal performance of the boiler can be improved. The volume of the boiler recirculation zone is 2.035m 3 , there is almost no high-temperature airflow impacting the water-cooled wall, and the overall pressure drop is 37.62Pa, indicating that the boiler flow field is well organized; the escape rate of impurity particles in the exhaust gas at the furnace outlet is 9.76%, the water-cooled wall adhesion rate is 13.3%, and the capture rate of the filtering and capturing components is only 76.94%, indicating that the position and size design of the impurity particle filtering and capturing components in the furnace are still defective. Long-term operation will lead to a considerable risk of corrosion or wear and perforation of the water-cooled wall in the furnace and the superheater and reheater at the rear of the boiler.

[0140] Step 12. Based on the post-processing performance evaluation results of the boiler described in step 11, appropriately adjust the burner air supply, furnace size, impurity particle filtering and capturing component position and size and other structural parameters of the boiler, set up a research plan according to the orthogonal method, and repeat steps 3 to 11 to achieve the purpose of structural optimization of this model of exhaust gas waste heat recovery boiler.

[0141] The present invention utilizes the advantages of low cost and high efficiency of the numerical simulation analysis method to achieve performance evaluation and structural optimization of waste heat recovery boilers for tail gas containing impurity particles in the smelting industry.

[0142] The analysis method of the present invention has wide applicability and is not limited to the yellow phosphorus smelting tail gas waste heat recovery boiler in the above embodiment. It can also be used to perform performance evaluation and structural optimization on different types of waste heat recovery boilers used with impurity-containing particle tail gas from smelting industries from different sources.

[0143] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the relevant field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A method for analyzing waste heat recovery boilers of tail gas containing impurities and particles in smelting industry, characterized in that: The following steps are involved: S1. Collect tail gas containing impurity particles from the smelting industry, separate the gas from the impurity particles after cooling, and obtain experimental data after measurement; The experimental data include the composition and proportion of gas components in the exhaust gas, the particle size distribution and true density of impurity particles in the exhaust gas; S2. Constructing a three-dimensional geometric model of a waste heat recovery boiler for treating tail gas containing impurities and particles in the smelting industry; S3, meshing the three-dimensional geometric model to obtain a mesh model; S4. Setting boundary conditions that meet the actual operation conditions based on the grid model; Set the parameters of the fluid phase and particle phase inside the boiler according to the experimental data obtained in S1; According to the actual operation of the waste heat recovery boiler, the calculation model, discrete format, numerical solution method and relaxation factor are set for the numerical simulation; S5, performing numerical simulation calculation on the grid model, first initializing the numerical simulation calculation domain and starting to solve, and obtaining the temperature field, pressure field, component field, velocity field and particle trajectory; S6, performing data post-processing on the temperature field, pressure field, component field, velocity field and particle trajectory to obtain data post-processing results; S7. Adjust the structural parameters of the waste heat recovery boiler according to the data post-processing results, and repeat S2-S6 to perform the structural optimization design of the waste heat recovery boiler for tail gas containing impurities in the smelting industry until the parameters in the post-processing results in S6 meet the preset requirements.

2. The method for analyzing waste heat recovery boiler of tail gas containing impurities in smelting industry according to claim 1 is characterized in that: In S1, sealed air bags are used to collect the tail gas containing impurities and particles from the smelting industry in the actual industrial process; If the exhaust gas temperature is higher than the operating temperature of the sealed air bag, the exhaust gas is pre-cooled before collection. During the collection process, it is ensured that there is no leakage of the exhaust gas. The collected exhaust gas has the same composition as the actual exhaust gas, which is used to ensure the accuracy of subsequent analysis. In S1, after the tail gas containing impurity particles in the smelting industry is cooled to room temperature, the gas and the impurity particles are separated, and the composition and proportion of the gas components in the tail gas are measured by gas chromatography, and the particle size distribution and true density of the impurity particles in the tail gas are measured by Malvern spray particle size analyzer and true density tester.

3. The method for analyzing waste heat recovery boiler of tail gas containing impurities in smelting industry according to claim 1 is characterized in that: S2 is specifically: based on the drawing parameters of the waste heat recovery boiler actually used to treat the tail gas containing impurities and particles in the smelting industry, the fluid domain of the waste heat recovery boiler is modeled at a 1:1 three-dimensional geometry using Solidworks software, and the three-dimensional geometric model of the waste heat recovery boiler is named in the calculation domain using the DesignModeler module in the Workbench platform of Ansys software.

4. The method for analyzing waste heat recovery boiler of tail gas containing impurities in smelting industry according to claim 1 is characterized in that: S3 is specifically as follows: meshing the three-dimensional geometric model with a hexahedral mesh, meshing the waste heat recovery boiler wall, swirl burner blades, and impurity particle capture component areas to obtain a mesh model, and performing a mesh quality check after meshing is completed.

5. The method for analyzing waste heat recovery boiler of tail gas containing impurities in smelting industry according to claim 1 is characterized in that: In S3, the parameters of the fluid phase and particle phase inside the boiler are set according to the experimental data of the tail gas containing impurities in the smelting industry, specifically: According to the composition and proportion of the gas components in the tail gas obtained in S1, the components of the mixed fluid phase inside the boiler are set. The thermal properties of the mixed fluid phase are calculated according to the component ratio, and the radiation characteristics select the wsggm-domain-based model; the combustion reaction of CO and CH4 needs to be considered when the waste heat recovery boiler is running; According to the particle size distribution and true density of impurity particles in the tail gas obtained by S1, the particle size distribution and true density of the particle phase inside the boiler are set; If the impurity particle content in the exhaust gas is less than 10%, the interaction between particles is ignored and the DPM discrete phase model is selected; if the impurity particle content is greater than 10%, the interaction between particles is considered and the DDPM discrete phase model is selected. In the discrete model, particles are injected from the boiler inlet in the form of surface injection, and the injection speed is consistent with the fluid phase.

6. The method for analyzing waste heat recovery boiler of tail gas containing impurities and particles in smelting industry according to claim 1 is characterized in that: In S4, the boundary conditions include inlet boundary conditions, outlet boundary conditions and wall boundary conditions; Inlet boundary conditions include velocity, temperature, turbulence intensity, and component ratio; The outlet boundary conditions include pressure, flow rate ratio, and escape of impurity particles; The wall boundary conditions need to be set to isothermal / adiabatic, with / without slip, and impurity particles being captured / rebounded according to the actual situation.

7. The method for analyzing waste heat recovery boiler of tail gas containing impurities in smelting industry according to claim 1 is characterized in that: In S4, the calculation model includes a turbulence model, a radiation model, a gas phase chemical reaction model, a discrete phase model and a drag model; The turbulence model selected is the Realizable k-ε model for medium swirl intensity; Select DO model for radiation model; The gas phase chemical reaction model is selected to deal with the finite rate / eddy dissipation combustion model of partially premixed flame and turbulence; The discrete phase model is selected between the DPM model and the DDPM model according to the actual situation; The drag model selects the Wen-Yu drag model, which is used to calculate the interaction force between the discrete phase and the fluid phase; In S4, the pressure term in the discrete format uses the Standard discrete format, and the other terms use the second-order upwind format; the other terms include components, velocity, and temperature; The Phase coupled SIMPLE algorithm was selected as the numerical solution method; The pressure relaxation factor was set to 0.2, the component-related relaxation factor was set to 1, and the relaxation factors of other items were set to 0.

4.

8. The method for analyzing waste heat recovery boiler of tail gas containing impurities in smelting industry according to claim 1 is characterized in that: In S6, the data post-processing is specifically as follows: Post-process the temperature field to obtain the average temperature of the boiler flue gas outlet and the uniformity of the temperature distribution in the furnace; Post-process the pressure field to obtain the overall and local pressure drops; Post-process the component field to obtain the burnout rate of the combustible component; Post-process the velocity field to obtain the volume of the boiler recirculation area, the temperature and velocity of the air flow near the water-cooled wall; Post-process the particle trajectory to obtain the furnace outlet escape rate, water-cooled wall adhesion rate, and capture rate of the filter capture component of the impurity particles; The thermal performance of the boiler is evaluated by the average temperature of the boiler flue gas outlet, the burnout rate of the combustible components and the uniformity of the temperature distribution in the furnace; The boiler flow field organization performance is evaluated based on the boiler recirculation area volume, air flow temperature and velocity near the water-cooled wall, and overall and local pressure drops; The degree to which the boiler is affected by corrosion or wear of impurity particles in the exhaust gas is evaluated based on the escape rate of the furnace outlet, the adhesion rate of the water-cooled wall, and the capture rate of the filtering and capturing components.

9. The method for analyzing waste heat recovery boiler of tail gas containing impurities in smelting industry according to claim 1 is characterized in that: In S7, the structural parameters of the waste heat recovery boiler include the air distribution of the burner, the size of the furnace, and the position and size of the impurity particle filtering and capturing component.

10. A waste heat recovery boiler analysis system for tail gas containing impurities and particles in smelting industry, characterized in that: include: A data acquisition module is used to acquire experimental data; the experimental data includes the composition and proportion of gas components in the exhaust gas, and the particle size distribution and true density of impurity particles in the exhaust gas; A construction module for constructing a three-dimensional geometric model of a waste heat recovery boiler for treating tail gas containing impurities and particles in the smelting industry; A meshing module is used to mesh the three-dimensional geometric model to obtain a mesh model; The condition setting module is used to set boundary conditions that meet the actual operation conditions based on the grid model; Set the fluid phase and particle phase parameters inside the boiler according to experimental data; According to the actual operation of the waste heat recovery boiler, the calculation model, discrete format, numerical solution method and relaxation factor are set for the numerical simulation; The simulation module is used to perform numerical simulation calculations on the grid model. First, the numerical simulation calculation domain is initialized and the solution is started to obtain the temperature field, pressure field, component field, velocity field and particle trajectory; The data post-processing module is used to perform data post-processing on the temperature field, pressure field, component field, velocity field and particle trajectory to obtain the data post-processing results; The structural adjustment and optimization module is used to adjust the structural parameters of the waste heat recovery boiler according to the data post-processing results, and repeatedly perform the structural optimization design of the waste heat recovery boiler for tail gas containing impurities in the smelting industry until the parameters in the post-processing results meet the preset requirements.

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