Negative pressure pneumatic conveying pipeline structure optimization method and negative pressure pneumatic conveying system

Abstract

The invention discloses a negative pressure pneumatic conveying pipeline structure optimization method and a negative pressure pneumatic conveying system.The method comprises the steps that a physical simulation geometric model is built based on currently-set conveying pipeline structure parameters, and a gas phase area and a particle motion area are extracted; performing steady-state calculation on the gas phase region to obtain a first flow velocity of the gas flow inlet; taking the first flow velocity as a boundary condition of a particle motion area, performing steady-state calculation on the particle motion area, and adding dispersed phase particles into a calculation result to construct a particle motion track; calculating the value of the reference index according to the particle motion trail; adjusting the structure parameter according to the reference index, and obtaining the reference index again; and selecting an optimal structure parameter according to the plurality of groups of obtained reference indexes. Based on the confirmation method, the design precision and optimization efficiency of the negative pressure pneumatic conveying pipeline are effectively improved, the abrasion of the pipeline can be effectively reduced, the service life of equipment is prolonged, and the maintenance cost is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of negative pressure conveying pipeline design, and in particular to a negative pressure pneumatic conveying pipeline structure optimization method and a negative pressure pneumatic conveying system. Background Art

[0002] Pneumatic conveying is an efficient and energy-saving material conveying method, which is widely used in chemical, metallurgical, building materials, food and other industries. According to the different conveying methods, pneumatic conveying can be divided into two categories: positive pressure pneumatic conveying and negative pressure pneumatic conveying. Among them, the negative pressure pneumatic conveying system uses a negative pressure fan to generate airflow in the pipeline to transport granular materials from one end of the pipeline to the other end. It has the advantages of simple pipeline structure, low energy consumption and strong adaptability, so it has been widely promoted in practical applications.

[0003] In the design process of negative pressure pneumatic conveying system, the reasonable configuration of the structural parameters of the conveying pipeline (such as pipe diameter, pipe length, number and angle of elbows, etc.) has an important impact on the conveying efficiency, energy consumption and stability of the system. Traditional structural optimization methods mainly rely on engineering experience and trial and error, which often require a lot of test verification, are time-consuming and labor-intensive, and it is difficult to ensure the optimization of design parameters. In addition, with the diversification of the particle size, density and other characteristics of the conveyed materials, traditional methods are unable to cope with complex working conditions and are difficult to meet the needs of modern industry for efficient and precise conveying systems.

[0004] In recent years, with the development of computer simulation technology, numerical simulation based on physical models has gradually become an important tool for pipeline design. However, the existing simulation methods still have the following shortcomings in practical applications. For example, when calculating the steady-state flow field in a negative pressure fluid delivery pipeline, it is difficult to set the boundary conditions, and the actual distribution and changes of the airflow in different areas of the pipeline cannot be accurately reflected, resulting in inaccurate prediction of particle motion trajectories, and the final obtained structural parameters are quite different from the actual ones.

[0005] In view of the above problems, a new pipeline design method based on computer simulation is urgently needed. Summary of the invention

[0006] The purpose of the present invention is to provide a negative pressure pneumatic conveying pipeline structure optimization method and a pressure pneumatic conveying system which utilize a physical simulation analysis model to accurately simulate and optimize a conveying pipeline to improve pipeline design efficiency.

[0007] In order to achieve the above object, the present invention provides a method for optimizing the structure of a negative pressure pneumatic conveying pipeline, wherein the conveying pipeline is used for conveying granular materials based on negative pressure pneumatic conveying provided by a negative pressure fan, and the confirmation method comprises: Based on the currently set structural parameters of the conveying pipeline, construct a physical simulation geometric model for discrete phase fluid analysis; The flow field in the physical simulation geometric model is divided into a gas phase region and a particle movement region, wherein the gas phase region is a single airflow flow region, and the particle movement region is a region where the airflow carries the material; Using the working parameters of the negative pressure fan as the boundary conditions of the gas phase region, performing steady-state calculation on the gas phase region to obtain a first flow velocity at the air flow inlet; Using the first flow velocity as a boundary condition of a particle motion region, performing steady-state calculation on the particle motion region, and adding discrete phase particles to the calculation results to construct a particle motion trajectory; According to the particle movement trajectory, a reference index value is calculated and obtained, wherein the reference index is used to characterize the conveying state and / or erosion rate of the particle movement area; adjusting the structural parameters according to the reference index, and re-obtaining the reference index; The optimal structural parameters are selected according to the obtained sets of reference indicators.

[0008] Preferably, the indices used to characterize the conveying state of the particle movement area in the reference indices include flow rate and pressure at the inlet and outlet of the particle movement area.

[0009] Preferably, the erosion rate is calculated based on a Finnie model.

[0010] Preferably, for the curved section of the conveying pipeline, the calculated erosion rate is corrected based on a preset correction coefficient and an average flow velocity at a current position.

[0011] Preferably, the correction coefficient is obtained based on a comparative test.

[0012] Preferably, the physical simulation geometric model is constructed based on a DPM model.

[0013] Preferably, the structural parameters include any one or more of pipe diameter, pipe length, elbow radius, pipe material, and pipe shape.

[0014] Preferably, in the physical simulation geometric model, the gas phase region and the particle motion region are meshed to discretize the continuous calculation domain into finite mesh units.

[0015] The present invention also provides a negative pressure pneumatic conveying system, which includes a negative pressure fan, a vacuum conveyor and a conveying pipeline; the conveying pipeline includes a first pipeline and a second pipeline, the negative pressure fan is connected to the vacuum conveyor through the first pipeline to provide a negative pressure environment in the vacuum conveyor; the vacuum conveyor is connected to a storage bin storing granular materials to be conveyed through the second pipeline, and the vacuum conveyor is used to receive the materials in the storage bin; the structural parameters of the conveying pipeline are confirmed based on the above-mentioned negative pressure pneumatic conveying pipeline structure optimization method.

[0016] Preferably, a filter screen is provided in the vacuum conveyor near the end connected to the first pipeline, and the filter screen is used to prevent the material from entering the first pipeline.

[0017] Compared with the prior art, the negative pressure pneumatic conveying pipeline structure optimization method provided by the above technical solution of the present invention has the following technical effects: 1. Improved design accuracy: By establishing a discrete phase fluid analysis geometric model and accurately dividing the flow field area into the gas phase area and the particle movement area, the flow characteristics of each area can be accurately reflected during the simulation. This refined simulation improves the accuracy of structural parameter design and reduces deviations in actual applications; 2. Optimization efficiency improvement: Steady-state calculation and particle motion trajectory model can quickly obtain key reference indicators (such as flow rate, erosion rate, etc.), and optimize by adjusting structural parameters or selecting the best from multiple groups of structural parameters. This process replaces the traditional inefficient design method that relies on experience and trial and error, greatly shortens the design cycle, and reduces manpower and time costs.

[0018] 3. Reduce energy consumption and erosion rate: Accurate structural parameter configuration optimizes the airflow and material conveying path, reducing energy loss. At the same time, by referring to the erosion rate evaluation in the index, it can effectively reduce pipeline wear, extend equipment service life, and reduce maintenance costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a planar structural diagram of the conveying system in an embodiment of the present invention.

[0020] Figure 2 It is a three-dimensional diagram of the pipeline structure of the transportation system in an embodiment of the present invention.

[0021] Figure 3 It is a flow chart of the method for optimizing the structure of a transport pipeline in an embodiment of the present invention.

[0022] Figure 4 This is a simulation effect diagram of the gas phase region in an embodiment of the present invention.

[0023] Figure 5This is a simulation effect diagram of the particle movement area when no particles are added in an embodiment of the present invention.

[0024] Figure 6 This is a simulation effect diagram when particles are added to the particle motion region under one of the structural parameters in an embodiment of the present invention.

[0025] Figure 7 This is a simulation effect diagram when particles are added to the particle motion region under another structural parameter in an embodiment of the present invention. DETAILED DESCRIPTION

[0026] In order to explain the technical content, structural features, achieved objectives and effects of the present invention in detail, the following is a detailed description in conjunction with the implementation methods and the accompanying drawings.

[0027] This embodiment discloses a method for optimizing the structure of a negative pressure pneumatic conveying pipeline, which is used to confirm the structural parameters of the conveying pipeline in a conveying system working based on negative pressure, so as to achieve the purpose of rapid design and molding.

[0028] like Figure 1 and Figure 2 The conveying system in this embodiment includes a negative pressure fan 1, a vacuum conveyor 2 and a conveying pipeline G.

[0029] The conveying pipeline G includes a first pipeline G1 and a second pipeline G2. The negative pressure fan 1 is connected to the vacuum conveyor 2 through the first pipeline G1 to provide a negative pressure environment in the vacuum conveyor 2. The vacuum conveyor 2 is connected to a storage bin 2 storing granular materials to be conveyed through the second pipeline G2. The vacuum conveyor 2 is used to receive the materials in the storage bin 2.

[0030] The working principle of the conveying system is as follows: after the negative pressure fan 1 is started, the vacuum conveyor 2 is evacuated through the first pipe G1, so that the granular material in the storage bin 2 enters the vacuum conveyor 2 through the second pipe G2. A transmission device can be configured under the vacuum conveyor 2 to transport the material in the vacuum conveyor 2 to other workstations.

[0031] For the conveying pipeline G in the conveying system, the first pipeline G1 is a single airflow channel, and the second pipeline G2 is a mixed channel for airflow and material.

[0032] In addition, in order to prevent particles from entering the first pipeline G1, a filter screen 4 is provided in the vacuum conveyor 2 near the end connected to the first pipeline G1. The filter screen 4 is used to prevent materials from entering the first pipeline G1.

[0033] For conveying systems of different purposes, it is necessary to design the structural parameters of the conveying pipeline G to achieve the ideal conveying effect and increase the service life.

[0034] Specifically, the pipeline parameters of the conveying pipeline G include any one or more of the pipe diameter, pipe length, elbow radius, pipe material, and pipe shape.

[0035] In this regard, the confirmation method in this embodiment is based on computer simulation technology to optimize and confirm the structural parameters of the conveying pipeline G to achieve the purpose of rapid design and molding. Figures 1 to 3 , the confirmation method comprises the following steps: S1: Based on the currently set structural parameters of the conveying pipeline G, a physical simulation geometric model for discrete phase fluid analysis is constructed.

[0036] This step is to convert the actual negative pressure pneumatic conveying pipeline system into a mathematical model that can be processed by the computer and establish its geometric shape in three-dimensional space. The model needs to include all the factors that affect the airflow and particle movement, such as: Pipe geometry: Accurately simulate pipe length, diameter, number of elbows, angles, and other special shapes such as reducers, branch pipes, etc.

[0037] Pipe material: Determine the material type of the pipeline, such as steel pipe, plastic pipe, etc. This parameter will affect the fluid friction coefficient and the pipeline wall erosion rate.

[0038] S2: The flow field in the physical simulation geometric model is divided into a gas phase region and a particle movement region, wherein the gas phase region is a single airflow flow region, and the particle movement region is a region where the airflow carries the material. Specifically, the gas phase region refers to the flow field region in the first pipeline G1, and part of the region in the vacuum conveyor, which mainly simulates the flow characteristics of the airflow, such as velocity, pressure, etc.

[0039] The particle movement area refers to the flow field area in the second pipeline G2 and a part of the area in the vacuum conveyor. This area mainly simulates the movement characteristics of particles in the airflow, such as speed, trajectory, collision, etc.

[0040] In addition, using appropriate meshing technology, you can choose tetrahedral meshing, hexahedral meshing, hybrid meshing, etc. The specific choice depends on the requirements of calculation accuracy and efficiency. Mesh the gas phase area and particle motion area, and discretize the continuous calculation domain into finite grid units so that the fluid mechanics equations can be solved using numerical methods. The higher the grid density, the higher the calculation accuracy, but the higher the calculation cost. Usually, it is necessary to select a reasonable grid density based on the complexity of the flow field area and the calculation requirements.

[0041] Meshes are usually generated using specialized mesh generation software, such as ANSYS ICEM CFD, ANSYS Meshing, Gambit, etc.

[0042] S3: Using the working parameters of the negative pressure fan 1 as the boundary conditions of the gas phase region, a steady-state calculation is performed on the gas phase region to obtain the first flow velocity of the air flow inlet C1. The first flow velocity is the flow velocity of the air flow flowing into the first pipe G1 at the interface between the first pipe G1 and the vacuum conveyor 2. Specifically, the working parameters of the negative pressure fan 1 include air volume and air pressure, which can be obtained by detection by a flow meter and a pressure sensor. This step simulates the flow state of the air flow in the pipe after the negative pressure fan is started.

[0043] It should also be noted that steady-state calculation of the gas phase region is to perform numerical simulation of the gas phase region in order to obtain a stable flow field in the gas phase region. Steady-state calculation refers to calculations that reach a state of equilibrium over time. In other words, the physical quantities of the system (such as velocity, pressure, temperature, etc.) no longer change over time, but maintain a stable value. The simulation effect diagram of the gas phase region in steady state is shown in the figure below. Figure 4 shown.

[0044] S4: Take the first flow rate as the boundary condition of the particle movement area, that is, the inlet flow rate of the gas phase area is taken as the outlet flow rate of the particle movement area (the flow rate of the air flow C2 at the outlet of the storage bin 2), and perform steady-state calculation on the particle movement area. The simulation effect diagram of the particle movement area in steady state is as follows: Figure 5 This step simulates the movement of particles in the pipe under the action of airflow.

[0045] S5: Obtain the physical properties of the material (such as material name, density, bulk density, particle size, etc.), and add discrete phase particles to the steady-state calculation results of the particle motion area to construct the particle motion trajectory. This step simulates the motion trajectory of particles in the airflow.

[0046] S6: According to the particle movement trajectory, a reference index value is calculated and obtained, where the reference index is used to characterize the transport state and / or erosion rate of the particle movement area.

[0047] S7: Adjust the structural parameters according to the reference index, and execute the above steps S1 to S6 to obtain the reference index again. Specifically, adjust the structural parameters according to the values ​​of the reference index, such as flow rate, pressure, erosion rate, etc. For example, if the erosion rate is too high, you can consider increasing the pipe diameter, changing the pipe material, adjusting the elbow angle, etc.

[0048] S8: Select the optimal structural parameters based on the obtained sets of reference indicators.

[0049] By repeatedly adjusting the structural parameters, several groups of reference indicators can be obtained, such as flow rate, pressure, erosion rate, etc. under different pipe diameters and different elbow angles. Then, according to the preset optimization goals, such as the highest transmission efficiency, the lowest erosion rate, the lowest energy consumption, etc., the optimal structural parameters are selected from multiple groups of reference indicators.

[0050] Through the above steps S1 to S8, the structural parameters of the negative pressure pneumatic conveying pipeline can be optimized and designed to improve the conveying efficiency and reduce pipeline wear and blockage problems. This method is based on computer simulation technology and can effectively simulate the flow field and particle movement inside the conveying pipeline, predict the pipeline erosion rate, and find the optimal pipeline structure by adjusting the parameters to meet the needs of modern industry for efficient and precise pneumatic conveying systems.

[0051] On the other hand, the indicators used to characterize the transport state of the particle movement area in the reference indicators include the flow rate and pressure at the inlet and outlet of the transport pipe G (i.e., the second pipe G1). Specifically, after the flow rate at the inlet and outlet of the particle movement area is calculated, the flow rate difference between the inlet and outlet is further obtained. After the pressure at the inlet and outlet of the particle movement area is calculated, the pressure difference between the inlet and outlet is further obtained. Finally, the structural parameters are evaluated by the flow rate difference, pressure difference, and erosion rate.

[0052] On the other hand, a physical simulation geometry model is constructed based on the DPM model, and the erosion rate is calculated based on the Finnie model.

[0053] The Finnie model is a well-known erosion model used to describe the erosion wear behavior of plastic materials under particle impact. For almost all plastic materials, erosion varies with the impact angle and velocity. The Finnie model quantifies this erosion wear by relating the wear rate to the kinetic energy ratio of the particle impacting the surface through a specific function.

[0054] For example, there is a negative pressure pneumatic conveying system used to convey kaolin powder. The system parameters are as follows: Negative pressure fan 1: 7.5KW, providing -40kpa negative pressure; Delivery pipeline G: DN50, length 15M, made of steel pipe; Material: Kaolin powder, density is 2.5g / cm³, bulk density is 0.7g / cm³, particle size is 1.5-2μm.

[0055] For this transportation system, it is necessary to optimize the pipeline structural parameters to improve the transportation efficiency and reduce pipeline wear and blockage problems. The process of optimizing the structural parameters using the above confirmation method is as follows.

[0056] 1. Construction of physical simulation geometry model Use CFD software to establish the physical simulation geometry model of the conveying pipeline G, extract the flow field area, divide the process area into the gas phase area and the particle movement area, and divide the two areas into grids. The grid density needs to be adjusted according to the actual situation, for example, the elbow area needs to be divided into a denser grid.

[0057] 2. Steady-state calculation 2.1 Set the boundary conditions of the gas phase area: the outlet wind speed of negative pressure fan 1 is 100 m / s and the pressure is -40 kPa.

[0058] 2.2 Perform steady-state calculations in the gas phase region and obtain that the air flow inlet velocity in the gas phase region is 80 m / s and the pressure is -30 kPa.

[0059] 2.3 Take the air flow inlet velocity as the boundary condition of the particle motion area and perform steady-state calculation of the particle motion area.

[0060] 3. Construct particle motion trajectory The physical parameters of kaolin powder were set as follows: density of 2.5 g / cm³ and particle size of 1.5 μm.

[0061] Setting the particle injection position and quantity: setting the particle injection position and quantity according to the actual situation, for example, from the storage bin 2 into the second pipeline G2.

[0062] The DPM model is used to calculate the particle motion trajectory and the erosion rate. In this embodiment, the DPM model solves the particle motion equation by numerical method, calculates the position and velocity of each particle at each time step, thereby generating the particle motion trajectory and calculating the reference index value, as shown in Table 1 (A). Under this structural parameter, the simulation effect of the erosion rate in the particle motion area is as follows: Figure 6 shown.

[0063] 4. Adjust parameters and optimize design If the currently calculated reference index value does not meet the requirements, then adjust the pipeline structure parameters, such as increasing the elbow angle, adjusting the pipeline length, etc.

[0064] Table 1

[0065] Re-perform simulation calculations to obtain new reference indicators.

[0066] By repeatedly adjusting the parameters, several groups of reference indicators are obtained, and finally the best group is selected, as shown in Table 1 (B). Then the simulation effect of the optimized particle motion area is as follows Figure 7 shown.

[0067] 5. Experimental Analysis The conveying system is built based on the final optimized structural parameters, and experimental verification is carried out to confirm the accuracy of the simulation results.

[0068] This example demonstrates a method for optimizing the structure of a negative pressure pneumatic conveying pipeline G based on CFD and DPM. This method can effectively simulate the flow field and particle movement inside the conveying pipeline G, predict the pipeline erosion rate, and find the optimal pipeline structure by adjusting parameters, thereby improving the conveying efficiency and reducing pipeline wear and blockage problems.

[0069] In addition, it should be noted that: The DPM model (Discrete Phase Model) is a model used to simulate the movement of discrete phases (such as particles, bubbles, droplets) in a continuous phase (such as gas or liquid).

[0070] The DPM model is widely used to analyze the motion of particles in fluids, such as: Particle trajectory: Predict the movement path of particles in the pipeline and identify potential blockage areas.

[0071] Diffusion of particles: Analyze the diffusion rate and extent of particles in the fluid and evaluate the uniformity of particles.

[0072] Particle Collision: Simulate the collision and interaction between particles and evaluate the wear and breakage of particles.

[0073] The DPM model simulates the trajectory and velocity of particles by tracking each discrete phase particle individually and calculating the forces acting on it in the fluid. The model takes into account factors such as the mass, shape, size, density, and drag, gravity, and buoyancy of the fluid on the particles.

[0074] CFD (Computational Fluid Dynamics) is a tool that uses numerical methods to solve fluid mechanics equations to simulate fluid flow and heat transfer phenomena.

[0075] CFD can be used to analyze various fluid flow problems, such as: Airflow path: Simulate the flow path of airflow in the pipe to understand the airflow velocity distribution and pressure distribution.

[0076] Turbulent characteristics of airflow: Analyze the turbulence level of airflow and predict the mixing efficiency and energy loss of airflow.

[0077] Heat transfer of airflow: simulate the heat transfer process of airflow and evaluate the temperature distribution and heat transfer efficiency of airflow.

[0078] CFD divides the fluid area into grids and then solves the fluid mechanics equations on each grid to obtain the values ​​of fluid velocity, pressure, temperature and other parameters at each grid point.

[0079] The above embodiment of the present application combines DPM and CFD to process the physical simulation geometric model, that is, in the negative pressure pneumatic conveying pipeline structure optimization method, the DPM model and the CFD model cooperate with each other to jointly simulate the behavior of the entire conveying system: By combining DPM and CFD, we can have a more comprehensive understanding of the airflow and particle flow in the negative pressure pneumatic conveying pipeline and optimize the pipeline structure parameters.

[0080] The specific structure of the DPM model and the specific calculation method of CFD are common knowledge in the art and will not be described in detail here.

[0081] On the other hand, for the elbow part of the conveying pipeline G (such as Figure 2 At position C3 in the figure), the calculated erosion rate has a significant deviation from the actual value under different pressures and speeds, which affects the judgment. Therefore, for the curved section of the conveying pipeline G, the calculated erosion rate is corrected based on the preset correction coefficient and the average flow velocity at the current position.

[0082] Specifically, in the actual test, the calculation method of the actual erosion rate P1 of the elbow part of the transmission pipeline G is as follows:

[0083] in, is the weight of the elbow before the experiment, is the weight of the elbow after the experiment, measured by the experiment. is the elbow angle, r is the elbow radius, and D is the inner diameter of the elbow.

[0084] If, based on the above confirmation method, the maximum erosion rate of the elbow part obtained in the simulation experiment is , the average flow velocity in the elbow is , then the correction factor can be calculated by the following formula :

[0085] Thus, the correction factor can be determined with just one experiment. Then, after adjusting the structural parameters each time and calculating the erosion rate of the elbow part of the transmission pipeline G, the formula is used again By making corrections, you can get an erosion rate that matches the actual situation.

[0086] In summary, the present invention discloses a method for optimizing the structure of a compressed air conveying pipeline G. First, by establishing a discrete phase fluid analysis geometric model and accurately dividing the flow field area into a gas phase area and a particle movement area, the flow characteristics of each area in the simulation process are accurately reflected. This refined simulation improves the accuracy of structural parameter design and reduces deviations in practical applications.

[0087] Secondly, the steady-state calculation and particle motion trajectory model can quickly obtain key reference indicators (such as flow rate, erosion rate, etc.), and optimize by adjusting the structural parameters or select the best from multiple sets of structural parameters. This process replaces the traditional inefficient design method that relies on experience and trial and error, greatly shortens the design cycle, and reduces manpower and time costs.

[0088] Furthermore, precise structural parameter configuration optimizes the airflow and material conveying path, reducing energy loss. At the same time, by referring to the erosion rate evaluation in the index, it can effectively reduce pipeline wear, extend equipment service life and reduce maintenance costs.

[0089] In addition, this method can adapt to a variety of material properties (such as particle size, density, etc.), has strong versatility and flexibility, and meets the diverse needs of modern industry for efficient and precise pneumatic conveying systems.

[0090] The above disclosure is only the preferred embodiment of the present invention, which certainly cannot be used to limit the scope of rights of the present invention. Therefore, equivalent changes made according to the scope of the patent application of the present invention are still within the scope covered by the present invention.

Claims

1. A method for optimizing the structure of a negative pressure pneumatic conveying pipeline, wherein the conveying pipeline is used for conveying granular materials by negative pressure pneumatic conveying based on a negative pressure fan, characterized in that: The confirmation method comprises: Based on the currently set structural parameters of the conveying pipeline, construct a physical simulation geometric model for discrete phase fluid analysis; The flow field in the physical simulation geometric model is divided into a gas phase region and a particle movement region, wherein the gas phase region is a single airflow flow region, and the particle movement region is a region where the airflow carries the material; Using the working parameters of the negative pressure fan as the boundary conditions of the gas phase region, performing steady-state calculation on the gas phase region to obtain a first flow velocity at the air flow inlet; Using the first flow velocity as a boundary condition of a particle motion region, performing steady-state calculation on the particle motion region, and adding discrete phase particles to the calculation results to construct a particle motion trajectory; According to the particle movement trajectory, a reference index value is calculated and obtained, wherein the reference index is used to characterize the conveying state and / or erosion rate of the particle movement area; adjusting the structural parameters according to the reference index, and re-obtaining the reference index; The optimal structural parameters are selected according to the obtained sets of reference indicators.

2. The method for optimizing the structure of a negative pressure pneumatic conveying pipeline according to claim 1, characterized in that: The indices used to characterize the conveying state of the particle movement area in the reference indices include flow rate and pressure at the inlet and outlet of the particle movement area.

3. The method for optimizing the structure of a negative pressure pneumatic conveying pipeline according to claim 1, characterized in that: The erosion rate was calculated based on the Finnie model.

4. The method for optimizing the structure of a negative pressure pneumatic conveying pipeline according to claim 1, characterized in that: For the curved section of the conveying pipeline, the calculated erosion rate is corrected based on a preset correction coefficient and an average flow velocity at a current position.

5. The method for optimizing the structure of a negative pressure pneumatic conveying pipeline according to claim 4, characterized in that: The correction factor is obtained based on comparative experiments.

6. The method for optimizing the structure of a negative pressure pneumatic conveying pipeline according to claim 1, characterized in that: The physical simulation geometric model is constructed based on the DPM model.

7. The method for optimizing the structure of a negative pressure pneumatic conveying pipeline according to claim 1, characterized in that: The structural parameters include any one or more of pipe diameter, pipe length, elbow radius, pipe material, and pipe shape.

8. The method for optimizing the structure of a negative pressure pneumatic conveying pipeline according to claim 1, characterized in that: In the physical simulation geometric model, the gas phase region and the particle motion region are meshed to discretize the continuous calculation domain into finite mesh units.

9. A negative pressure pneumatic conveying system, characterized in that: It includes a negative pressure fan, a vacuum conveyor and a conveying pipeline; the conveying pipeline includes a first pipeline and a second pipeline, the negative pressure fan is connected to the vacuum conveyor through the first pipeline to provide a negative pressure environment in the vacuum conveyor; the vacuum conveyor is connected to a storage bin storing granular materials to be conveyed through the second pipeline, and the vacuum conveyor is used to receive the materials in the storage bin; the structural parameters of the conveying pipeline are confirmed based on the negative pressure pneumatic conveying pipeline structure optimization method described in any one of claims 1 to 8.

10. The negative pressure pneumatic conveying system according to claim 9, characterized in that: A filter screen is also provided in the vacuum conveyor near one end connected to the first pipeline, and the filter screen is used to prevent the material from entering the first pipeline.

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