CN111814381B - Glass tin bath working model and its establishment method - Google Patents

Abstract

The invention discloses a working model of a glass tin bath and a method for establishing the working model. The working model of the glass tin bath adopts finite element simulation software to simulate the temperature and velocity distribution of the glass ribbon and the temperature and velocity distribution of the protective gas in the glass tin bath forming process. Through simulation, this working model can simulate the working principle of the glass tin bath at low cost, and has guiding significance for the design and production process of the tin bath.

Description

Glass tin bath working model and its establishment method

Technical field

The invention relates to glass tin bath forming process modeling technology, and specifically relates to a glass tin bath working model and its establishment method.

Background technique

In the glass production process, the tin bath is an important thermal equipment in the glass production process and is the glass forming area. The biggest difference between the tin bath and thermal equipment such as kilns and annealing kilns is that the tin bath contains liquid tin that is easily oxidized at high temperatures. Therefore, the space of the tin bath is also filled with protective gas to prevent the oxidation of the liquid tin.

After the glass raw material is heated in the kiln, it passes through the cooling part and launder of the glass kiln, and the molten glass in the kiln with a temperature of about 1100°C is transported to the surface of the tin bath. Under a certain temperature system , relying on the surface tension of the liquid-liquid-gas three-phase system and its own gravity, it is spread and polished on the tin liquid surface, and is thinned or thickened by the edge drawing machine to form glass ribbons of different thicknesses, thereby producing glass ribbons of different thicknesses. glass plate. Because the temperature in the tin bath is very high (generally above 1050°C), complex physical and chemical reactions will occur. Oxygen will react with tin to form tin oxides (SnO ₂ , SnO), which will contaminate the glass and cause it to produce light. Defects such as distortion, tin staining, fog spots, etc. Therefore, during the glass forming process, reducing protective gas (N ₂ + H ₂ ) needs to be introduced into the upper space of the tin bath to prevent the oxidation of the tin liquid and ensure that the tin liquid is bright and clean, thus Will not contaminate the lower surface of the glass.

In the glass forming process, the glass liquid is transformed into a glass plate, which has the characteristics of large deformation and difficulty in determining the boundary. As the tonnage of the existing glass production line continues to increase, the thickness of the glass plate becomes thinner and thinner, and the width of the original glass plate increases, and the As the lead speed increases, the edge reflow intensifies, resulting in the increasing lateral temperature difference of the glass plate in the tin bath. After the glass is pulled out of the tin bath, there are quality problems such as flatness, thickness difference and uniformity. In the past, craftsmen relied on experience to perform experimental operations, which required long-term practice on the production line to explore, consuming a lot of capital, time and labor costs. In particular, some tasks were difficult to complete through experiments. Therefore, it is very necessary to use numerical simulation methods to simulate the working state of the glass tin bath and establish a working model of the glass tin bath. Since there are many factors that affect the glass forming process in the tin bath, there is currently no effective method that can be used to simulate the glass tin bath. Working model of the slot working state.

Contents of the invention

The object of the present invention is to provide a working model of a glass tin bath that can effectively simulate the working state of a glass tin bath and a method of establishing the same.

In order to achieve the above objectives, the present invention mainly provides the following technical solutions:

A method for establishing a working model of a glass tin bath, including the following steps:

Step 1: Establish a geometric model: Use computer modeling software to establish a geometric model including the glass strip space and the protective gas space based on the prototype of the glass tin bath;

Step 2: Establish a network model: Use finite element analysis software to mesh the glass strip space and protective gas space in the established geometric model respectively (hexahedral structure is preferably used for mesh division) to form a mesh model;

Step 3: Establish a mathematical model: Based on the composition and properties of the glass ribbon and protective gas, combined with the glass production process, select an engineering model algorithm that simulates the working state of the glass tin bath and the energy equation therein, and determine the space and energy equation of the glass ribbon based on this energy equation. Protect the boundary conditions of the boundary parts of the gas space, and then input the determined numerical values of the boundary conditions into the grid model to establish a digital grid model. The digital grid model and energy equation form a mathematical model for calculation, as a glass tin bath working model.

The above-mentioned method of establishing the working model of the glass tin bath also includes a model optimization step: inputting the distance between the glass ribbon and the entrance of the glass tin bath as a variable into the energy equation of the mathematical model, performing iterative calculations on the digital grid model, and obtaining the glass tin The temperature and velocity values of the glass ribbon and protective gas in different areas of the tank are compared and analyzed. The mathematical model calculation results and the actual measurement data are compared and analyzed. When the difference between the two is within the predetermined deviation range, the mathematical model determines that the glass Tin bath working model; otherwise, return to step 2 to re-mesh, or return to step 3 to change the boundary condition value.

In the first step of the method for establishing the working model of the glass tin bath, the parameters of the glass tin bath prototype include: the wide section size, the shrinkage section size, the narrow strip size, the area location of the edge drawing machine and the air inlet of the internal space of the glass tin bath. The location of the area where the mouth is located (including the number and distribution of air inlets); the geometric model parameters of the glass strip space and protective gas space are basically the same as the parameter values of the glass tin bath prototype.

In the above method of establishing the working model of the glass tin bath, the glass ribbon space in the geometric model is divided into the area where the edge drawing machine is located and the general area. Step 2 divides the general area of the glass ribbon space into uniform grids according to the requirements of normal calculations. The edge drawing machine performs a denser grid division in the area; the protective gas space in the geometric model is divided into the area where the air inlet is located and the general area. Step 2 performs a uniform grid on the general area of the protective gas space in accordance with the requirements of normal calculations. Divide the area where the air inlet is located into a denser mesh.

In the above-mentioned method of establishing the working model of the glass tin bath, the engineering model used in step three to simulate the working state of the glass tin bath adopts the k-ε turbulence model, and the selected energy equation is:

Among them, x _j is the dependent variable, which represents the temperature and velocity of the medium under certain conditions; x _i is the independent variable, which represents the distance between the glass ribbon and the entrance of the glass tin bath; for a glass ribbon with a specific thickness or a specific gas, u _i is a constant, representing the turbulent velocity of the medium; μ is the atmospheric turbulence velocity under the standard state; G _k represents the turbulent kinetic energy generated by the laminar velocity gradient, G _b represents the turbulent kinetic energy generated by buoyancy, and Y _M represents the compressible turbulent flow , the fluctuations caused by the transitional diffusion, C ₁ , C ₂ , C ₃ are constants, σ _k and σ _ε are the turbulent Prandtl numbers of the k equation and ε equation respectively, S _k and S _ε are the source terms, which are determined by chemical reactions and radiative heat transfer decisions;

μ _t is determined by the following formula:

Among them, μ _t represents the turbulent velocity of the medium under a certain temperature condition converted into the turbulent velocity of the atmosphere under the standard state, which is a constant; ρ is a constant, representing the density of the medium; C _μ is a constant; κ refers to the κ equation, which is an exact equation ; ε refers to the ε equation derived from empirical formula; among them, C ₁ =1.44, C ₂ =1.92, C _μ =0.09, C ₃ =0.69, σ _k =1.0, σ _ε =1.3.

In the third step of the method for establishing the working model of the glass tin bath, the boundary parts of the glass ribbon space include the glass ribbon entrance part, the glass ribbon exit part, the glass ribbon surface part and the wall part where the glass ribbon contacts the glass tin bath, so The boundary part of the protective gas includes a protective gas inlet part and a protective gas outlet part;

The boundary conditions of the glass ribbon inlet and the protective gas inlet are both temperature and velocity. The boundary conditions of the glass ribbon exit and the protective gas outlet are both pressure and temperature. The surface of the glass ribbon and the wall where the glass ribbon contacts the glass tin bath The boundary conditions of the parts are all temperature.

In the above-mentioned method of establishing the working model of the glass tin bath, the boundary condition values input in step three also include: the temperature value of the glass liquid and the inflow velocity value of the glass liquid at the entrance of the glass ribbon (A1), and the value of the glass liquid at the exit of the glass ribbon (A2). Glass ribbon temperature value and glass ribbon pressure value, protective gas entry velocity value and protective gas temperature value at the protective gas inlet (B1), protective gas pressure value and protective gas temperature value at the protective gas outlet (B2), glass The temperature value of the wall surface in contact with the glass tin bath and the temperature value of the surface part of the glass ribbon (A3).

In the above method of establishing the working model of the glass tin bath, the temperature distribution on the surface of the glass ribbon adopts the slow cooling temperature system. The surface of the glass ribbon is treated according to the constant temperature moving surface. The order of the glass ribbon from the entrance of the glass tin bath to the exit of the glass tin bath is based on the glass. The distance between the belt and the entrance of the glass tin bath is divided into various temperature segments. The surface temperature at the center point of each segment is used as the boundary condition value input for each temperature segment (that is, the temperature boundary condition value of the surface of the glass ribbon).

In the above method of establishing the working model of the glass tin bath, the temperature distribution on the surface of the glass ribbon adopts the slow cooling temperature system. The surface of the glass ribbon is treated according to the constant temperature moving surface. The order of the glass ribbon from the entrance of the glass tin bath to the exit of the glass tin bath is based on the glass. The distance between the belt and the entrance of the glass tin bath is divided into various temperature sections. According to the measured data of the surface temperature of the glass belt under stable working conditions, a polynomial curve is fitted, and the ordinate temperature value of the polynomial curve corresponding to the predetermined sampling point position is obtained. The boundary condition value input as each temperature section (that is, the temperature boundary condition on the surface of the glass ribbon).

In the above-mentioned method of establishing the working model of the glass tin bath, the wall temperatures of the glass ribbon and the glass tin bath are in contact with the same constant temperature boundary condition, or the wall temperatures on both sides of the glass tin bath adopt different constant temperature boundary conditions.

The working model of the glass tin bath established by the above method also belongs to the protection scope of the present invention.

Compared with the prior art, the beneficial effects of the present invention are:

The method for establishing a working model of the glass tin bath of the present invention fully considers the particularity of the working of the glass tin bath, divides the geometric model into two spaces, and considers not only the temperature and flow rate of the glass liquid, but also the temperature and flow rate of the protective gas on the glass forming. According to the influence of the glass tin bath, personalized grid division and boundary conditions are set for different spaces, and appropriate energy equations are selected, so that the working model of the glass tin bath can match the actual working state of the glass tin bath. The present invention simulates the temperature and velocity distribution of the glass ribbon and the temperature and velocity distribution of the protective gas in the glass tin bath forming process through the established working model of the glass tin bath. The working model can simulate the working principle of the glass tin bath at low cost and The improvement of the existing glass tin bath structure and the design and production process optimization of the new glass tin bath are of guiding significance; using this glass tin bath working model to transform or optimize the glass tin bath can save production costs and reduce the difficulty of process optimization. , strong reliability and easy to operate.

Description of drawings

Figure 1 is a schematic flow diagram of an embodiment of the present invention;

Figure 2-1 is a three-dimensional diagram of the geometric model and mesh division of the glass ribbon according to the embodiment of the present invention. The length direction is the x-axis, the width direction is the y-axis, and the height direction is the z-axis;

Figure 2-2 is a three-dimensional diagram of the protective gas geometric model and mesh division according to the embodiment of the present invention. The length direction is the x-axis, the width direction is the y-axis, and the height direction is the z-axis;

Figure 3 is a temperature distribution diagram of the glass ribbon in the x-y section according to the embodiment of the present invention;

Figure 4 is a temperature distribution diagram on the x-z section of the glass ribbon according to the embodiment of the present invention;

Figure 5 is a velocity distribution diagram of the glass ribbon in the x-y section according to the embodiment of the present invention;

Figure 6 is a velocity distribution diagram of the glass ribbon in the x-z section according to the embodiment of the present invention;

Figure 7 is a temperature distribution diagram of the protective gas in the x-y space when the top is ventilated according to the embodiment of the present invention;

Figure 8 is a velocity distribution diagram of the protective gas in x-y space during top ventilation according to the embodiment of the present invention;

Figure 9 is a velocity vector distribution diagram of the protective gas in x-y space during top ventilation according to the embodiment of the present invention;

Figure 10 is a temperature distribution diagram of the protective gas in the y-z space during top ventilation according to the embodiment of the present invention;

Figure 11 is a velocity distribution diagram of the protective gas in the y-z space during top ventilation according to the embodiment of the present invention;

Figure 12 is a velocity vector distribution diagram of the protective gas in the y-z space during top ventilation according to the embodiment of the present invention;

Figure 13 is a schematic diagram of the polynomial fitting curve of the surface temperature of each temperature section of the glass liquid surface.

Main labels:

A1-Glass liquid inlet; A2-Glass ribbon outlet; A3-Glass liquid level; A4-The area where the edge drawing machine is located; B1-The protective gas inlet; B2-The protective gas outlet; B3-The area where the air inlet is located; B4-General area.

Detailed ways

The present invention will be further described in detail below with reference to specific embodiments, but this is not intended to limit the present invention. In the following description, different "one embodiment" or "embodiment" do not necessarily refer to the same embodiment. Furthermore, the specific features, structures, or characteristics of one or more embodiments may be combined in any suitable combination.

Figure 1 is a schematic flow chart of a method for establishing a working model of a glass tin bath according to an embodiment of the present invention. Referring to Figure 1, the overall idea of establishing the working model of the glass tin bath is as follows:

A geometric model was established using the glass tin bath as a prototype, and the glass strip space and protective gas space in the geometric model were meshed respectively. Since the glass ribbon after glass formation is in the shape of a plate, it also presents a hexahedral state and structure as a whole. Using a hexahedral structure to divide the mesh can display the proper state of the glass ribbon to the maximum extent, making the working model closer to the actual working state. Of course, it also Other meshing principles are applicable, and the hexahedral structure meshing principle is the optimal choice for this invention.

Based on the composition and properties of the glass ribbon and protective gas, combined with the glass production process (i.e., the viscosity curve and thermal conductivity of the glass liquid as it changes with temperature), a model algorithm for simulating the work of the glass tin bath and its energy equation are selected to determine the model's Boundary conditions. Considering that the forming process of the glass ribbon is basically a turbulent flow process, the standard κ-ε model is selected, and the basic parameters of the energy equation are determined based on the composition and properties of the glass ribbon and protective gas.

According to the actual production situation (the glass liquid enters the interior of the glass tin bath from the entrance of the glass tin bath and gradually forms a glass ribbon, which is referred to as glass ribbon for simplicity below), the boundary parts of the glass ribbon space and the space in contact with the glass ribbon are protected The boundary conditions of the boundary parts of the gas space are numerically input into the grid model to digitize the grid model. The digital grid model and the selected energy equation constitute a mathematical model for simulating the working state of the glass tin bath. The boundary between the glass ribbon space and the protective gas space includes the glass ribbon entrance area, the glass ribbon exit area, the glass ribbon surface area, the protective gas inlet area, the protective gas outlet area, and the wall area where the glass ribbon contacts the glass tin bath, where the glass The inlet boundary conditions of the belt space and the protective gas space are both temperature conditions and velocity conditions. The exit boundary conditions of the glass belt space and the exit boundary conditions of the protective gas space are both pressure conditions and temperature conditions. The surface of the glass belt space The part (that is, the lower surface of the protective gas) adopts constant temperature movement (referring to the temperature of the upper surface in the length direction of the tin bath, that is, the temperature of the upper surface in the forward direction of the glass ribbon, which is determined according to the forming needs of the glass ribbon) surface setting; the contact between the glass ribbon and the glass tin bath The wall area adopts constant temperature conditions.

The established working model of the glass tin bath simulates the temperature field and velocity field of the glass ribbon and the temperature field and flow field of the protective gas to obtain the temperature field and velocity field distribution of the glass ribbon, the spatial temperature field distribution of the protective gas and Velocity field distribution.

Among them, the initial glass ribbon surface temperature distribution adopts a slow cooling temperature system, and the surface of the glass ribbon is treated according to a constant temperature moving surface. According to the order of the glass ribbon from the entrance of the tin bath to the exit of the tin bath, the glass ribbon is divided into various temperature segments according to the distance between the glass ribbon and the entrance of the tin bath. The temperature value of the center point of each temperature segment is taken as the surface temperature value of each temperature segment, and Import the grid model; you can also fit the polynomial curve based on the actual measured original temperature data of each temperature section, and use the value of the ordinate of the polynomial curve corresponding to the sampling point as the surface temperature value of each temperature section.

Comparative analysis of the temperature values and speed values of the glass ribbon and protective gas in different areas of the glass tin bath by solving and calculating the obtained mathematical model and the actual measured temperature values and speed values can verify whether the above-mentioned glass tin bath working simulation process is consistent with reality. The working status of the glass tin bath (whether it is consistent with the actual process).

The embodiment of the present invention uses ANSYS software to establish a geometric model based on the glass tin bath prototype, and meshes the glass ribbon space and protective gas space in the geometric model respectively; according to the composition and properties of the glass ribbon and protective gas, combined with glass production process, select the engineering model algorithm and the energy equation in it, determine the boundary conditions at the boundary between the glass strip space and the protective gas space, input the determined boundary conditions numerically into the grid model, digitize the grid model, and use the digital grid model and the determined energy equation form a mathematical model that can be solved and calculated. On this basis, the mathematical model can be further verified or optimized by comparing and analyzing the calculated temperature and velocity distribution of the glass ribbon and protective gas with the actual measured temperature and velocity distribution of the glass ribbon and protective gas. .

As a preferred option, the flow models of the glass ribbon space and the protective gas space adopt the k-ε turbulence model, and the velocity energy equation is selected; the hexahedral structure is used through the ANSYS ICEM-CFD software to calculate the glass ribbon space and protective gas in the geometric model. The spaces are divided into grids respectively. The boundary conditions of the glass ribbon space and the protective gas space are set as follows: the entrance conditions of the glass ribbon are speed conditions and temperature conditions, and the outlet conditions are pressure conditions and temperature conditions; the temperature distribution on the surface of the glass ribbon adopts the slow cooling temperature system (inside the glass tin bath A constant-temperature moving surface setting is adopted, that is, once the properties and specifications of the glass are determined, the temperature corresponding to each position inside the glass tin bath remains unchanged, but the temperature gradually decreases as the distance between the glass ribbon and the entrance of the glass tin bath increases); The wall surface in contact with the glass tin bath adopts constant temperature boundary conditions.

The above ideas are used to simulate the working process of the glass tin bath, that is, the temperature and velocity distribution of the glass ribbon and protective gas in the glass tin bath forming process are simulated. The steps of establishing the working model of the glass tin bath include:

Step 1: Establish a geometric model: Use computer modeling software to use the glass tin bath as a prototype to establish a geometric model including the glass strip space and the protective gas space.

Specifically, the prototype parameters of the glass tin bath include: the wide section size of the internal space of the glass tin bath, the shrinkage section size, the narrow strip size, the regional location of the edge drawing machine and the regional location of the air inlet (including the number of air inlets and their distribution); the geometric model parameters of the glass ribbon space and protective gas space are basically the same as the values of the prototype parameters of the glass tin bath.

Step 2: Establish a mesh model: Use finite element analysis software to mesh the glass ribbon space and protective gas space in the established geometric model respectively (for example, the meshes are divided into hexahedral structure meshes) to form a network. lattice model.

Specifically, the glass ribbon space in the geometric model is divided into the area where the edge drawing machine is located and the general area. The general area of the glass ribbon space is divided into uniform grids according to the requirements of normal calculations, and a denser mesh is used for the area where the edge drawing machine is located. The protective gas space in the geometric model is divided into the area where the air inlet is located and the general area. According to the requirements of normal calculations, the general area of the protective gas space is divided into uniform grids, and a more uniform grid is used for the area where the air inlet is located. Divide into dense grids.

Step 3: Establish a mathematical model: Based on the composition and properties of the glass ribbon and protective gas, combined with the glass production process, select an engineering model algorithm that simulates the work of the glass tin bath and the energy equation therein; determine the space and protection of the glass ribbon based on this energy equation The boundary conditions of the boundary parts of the gas space are then input into the grid model to establish a digital grid model. The digital grid model and the energy equation form a mathematical model for calculation, which works as a glass tin bath. Model. Among them, the boundary parts of the glass ribbon space include the glass ribbon entrance part, the glass ribbon exit part, the glass ribbon surface part and the wall part where the glass ribbon contacts the glass tin bath, and the boundary part of the protective gas includes the protective gas inlet part and the protective gas outlet part. ;The inlet boundary conditions of the glass ribbon space and the inlet boundary conditions of the protective gas space are both temperature conditions and velocity conditions. The outlet boundary conditions of the glass ribbon space and the outlet boundary conditions of the protective gas space are both pressure conditions and temperature conditions. The glass ribbon space The surface part adopts slow cooling temperature system; the wall part where the glass ribbon contacts the glass tin bath adopts constant temperature boundary condition.

The above steps complete the mathematical modeling of the working process of the glass tin bath. Whether the established mathematical model is reasonable and consistent with the actual process parameters requires verification and analysis of the established mathematical model:

The distance between the glass ribbon and the entrance of the glass tin bath is entered as a variable into the energy equation of the mathematical model, and the digital grid model is iteratively solved to obtain the temperature values and velocities of the glass ribbon and protective gas in different areas of the glass tin bath. value; compare and analyze the calculation results of the mathematical model with the actual measurement data to verify the rationality and feasibility of the established mathematical model.

Based on the above feasibility analysis results, the mathematical model can be adjusted and optimized until the calculation and solution results of the established mathematical model tend to be consistent with the actual process data (that is, within the error range that meets the requirements).

The following takes a 150t/d (referring to the production capacity of the glass production line as 150 tons per day) tin bath for producing medium-aluminum glass (the mass content of aluminum oxide in the glass is generally between 4% and 8%) as an example to describe the glass tin of the present invention. The establishment method and effect of the groove working model are further explained.

Example 1: Establishment of working model of glass tin bath and simulation method of working of glass tin bath

Step 1, establishment of geometric model:

Taking a glass tin tank that produces 150t/d of medium-aluminum glass as a prototype, Haochen CAD software was used to establish a geometric model including the glass strip space and the protective gas space.

The main parameters of the prototype of the glass tin bath are: the length of the glass tin bath is 37.8 meters, the wide section is 5.2 meters, and the narrow section is 4.5 meters. The area where the edge drawing machine is located is 4700mm from the entrance of the glass tin bath (the first pair of edge drawing machines) to At 18000mm (the twelfth pair of edging machines), there are a total of 14 air inlets on the top of the glass tin bath, which are symmetrical and distributed in an array with the axial direction of the tin bath as the center. Specifically, the wide section is 24m×5.2m (length×width), the length of the shrinking section is 3m and the width changes linearly, and the narrow section is 10.8m×4.5m (length×width).

The glass tin tank is filled with tin liquid. When modeling, the space above a certain height of the tin liquid (the height is the same as the designed glass thickness) is defined as the glass ribbon space A (the glass liquid forms a glass ribbon in this space). The tin The space in the tank except for the tin liquid is defined as the protective gas space B (the protective gas fills the entire B space in gaseous form. Since the thickness of the medium-aluminum glass ribbon is very thin, relative to the height of the protective gas, the thickness of the glass ribbon can be ignored), A The volume is much smaller than B volume. The geometric parameters of the glass strip space and protective gas space in the built geometric model are basically the same as those of the tin bath prototype.

Step 2, establishment of grid model:

In this step, ANSYS ICEM-CFD software is used to mesh the glass strip space and protective gas space of the geometric model respectively (the meshing in this embodiment adopts a hexahedral structure), and the mesh is refined in local areas (to improve the mesh quality). To meet the requirements of normal calculation), a total of about 200,000 grids were divided to establish a grid model of the working state of the glass tin bath.

The glass ribbon space A is further subdivided into the area A4 where the edge drawing machine is located (the edge drawing machine is represented by parallel thick lines in Figure 2-1) and the general area. The general area is evenly divided using a grid with a predetermined density. The area where the edge drawing machine is located A4 uses a denser grid for division. The grid division results of the glass strip space A are shown in Figure 2-1. The number of grids in the space A is about 90,000.

The protective gas space B is further subdivided into the area B3 where the air inlet is located and the general area B4. The area B3 where the air inlet is located refers to the array-distributed protective gas inlet part B1 centered on the line connecting the length and width of the tin bath. The area formed by the expansion (see Figure 2-2) and the area outside the area where the air inlet is located is defined as the general area B4. Among them, the general area B4 is evenly divided using a grid with a predetermined density, and the area B3 where the air inlet is located is divided using a denser grid. The grid division of the protective gas space B is shown in Figure 2-2. In Figure 2-2 The solid point position indicates the air inlet (ie, the protective gas inlet part B1, multiple air inlets are set on the top of the tin bath). The number of grids in the B space is about 110,000.

Step three, establishment of mathematical model:

This step establishes a mathematical model to simulate the working state of the glass tin bath (i.e., the temperature field and flow field of the glass ribbon and the temperature field and flow field of the protective gas). It is based on the composition and properties of the glass ribbon and protective gas, combined with the glass production process. First select the engineering model algorithm that simulates the working state of the glass tin bath and the energy equation in the algorithm that matches the glass production process; determine the boundary between the glass ribbon space and the protective gas space based on the energy equation (the boundary of the glass ribbon space includes The entrance part of the glass ribbon, the exit part of the glass ribbon, the surface part of the glass ribbon and the wall part where the glass ribbon contacts the glass tin bath, the boundary part of the protective gas includes the protective gas inlet part and the protective gas outlet part) and the boundary conditions; then the determined The boundary conditions are numerically input into the grid model to establish a digital grid model. The digital grid model and energy equation form a mathematical model for calculation.

In this embodiment, based on the prototype of the glass tin bath and the actual production conditions, the k-ε turbulence model algorithm is used to simulate the temperature field of the glass ribbon and the velocity field of the protective gas. The velocity energy equation in the k-ε model is selected to determine the glass ribbon. The boundary condition values of each boundary part (A1-A3) of space A and each boundary part (B1, B2) of protective gas space B are added to the grid model, and a model is established to calculate and solve the temperature field of the glass ribbon and the protective gas. Mathematical model of flow field distribution.

Specifically, considering that the forming process of medium-aluminum glass is basically a turbulent flow process, the standard κ-ε model is selected.

The standard κ-ε model is a semi-empirical formula, mainly based on turbulent kinetic energy and diffusivity. The κ equation is an exact equation, and the ε equation is an equation derived from an empirical formula. The model assumes that the flow field is entirely turbulent and the viscosity between components is negligible. The specific formula of the energy equation is as follows:

Among them, x _j is the dependent variable, which represents the temperature and velocity of the medium under certain conditions; x _i is the independent variable, which represents the distance between the glass ribbon and the entrance of the glass tin bath; for a glass ribbon with a specific thickness or a specific gas, u _i is a constant, representing the turbulent velocity of the medium; μ is the atmospheric turbulence velocity under the standard state; G _k represents the turbulent kinetic energy generated by the laminar velocity gradient, G _b represents the turbulent kinetic energy generated by buoyancy, and Y _M represents the compressible turbulent flow , the fluctuations caused by the transitional diffusion, C ₁ , C ₂ , C ₃ are constants, σ _k and σ _ε are the turbulent Prandtl numbers of the k equation and ε equation respectively, S _k and S _ε are the source terms, which are determined by chemical reactions and radiative heat transfer decisions;

μ _t is determined by the following formula:

Among them, μ _t represents the turbulent velocity of the medium under a certain temperature condition, converted into the turbulent velocity of the atmosphere under standard conditions, which is a constant (different according to the thickness of the glass); ρ is a constant, representing the density of the medium (the amount that changes with temperature) ; C _μ is a constant; κ refers to the κ equation, which is an exact equation; ε refers to the ε equation derived from an empirical formula.

The commonly used constants of the model are as follows: C ₁ =1.44, C ₂ =1.92, C _μ =0.09, C ₃ =0.69, σ _k =1.0, σ _ε =1.3.

The boundary locations and boundary conditions are determined based on the standard κ-ε model. The boundary between the glass ribbon space and the protective gas space includes the glass ribbon entrance area, the glass ribbon exit area, the glass ribbon surface area, the protective gas inlet area, the protective gas outlet area, and the wall area where the glass ribbon contacts the glass tin bath, where the glass The inlet boundary conditions of the belt space and the protective gas space are both temperature conditions and velocity conditions. The exit boundary conditions of the glass belt space and the exit boundary conditions of the protective gas space are both pressure conditions and temperature conditions. The surface of the glass belt space Part (that is, the lower surface of the protective gas) adopts a slow cooling temperature system (fixed temperature moving surface setting, which means that the temperature of the upper surface in the length direction of the tin bath, that is, the moving direction of the glass ribbon gradually decreases according to the moving temperature of the glass ribbon); the glass ribbon and the glass tin Constant temperature boundary conditions are adopted for the wall parts where the grooves are in contact.

This embodiment is based on the production data of a 150t/d medium-alumina glass tin bath, the composition of the medium-alumina glass and the actual measured viscosity and temperature curves of the glass ribbon, and the space and temperature of the glass ribbon shown in Figure 2-1 and Figure 2-2 Set boundary conditions on the grid model of the protective gas space. The input boundary condition values are:

(1) The inflow speed of the molten glass at the entrance A1 of the glass ribbon is 0.16m/s, and the temperature of the molten glass at the entrance A1 of the glass ribbon is 1373.15K;

(2) The glass ribbon outlet temperature at the glass ribbon outlet A2 is 873.15K, and the pressure at the glass ribbon outlet A2 is maintained at a slightly positive pressure of 5Pa;

(3) The protective gas entry speed at the protective gas inlet B1 is 2m/s, the protective gas temperature at the protective gas inlet B1 is 673.15K; the protective gas outlet pressure at the protective gas outlet B2 is 5Pa, and the protective gas outlet The protective gas temperature at location B2 is 873.15K;

(4) Surface conditions of the glass ribbon: The temperature distribution of the surface area A3 of the glass ribbon adopts a slow cooling temperature system and is treated according to a constant temperature moving surface. The glass ribbon is divided into various temperature sections according to the distance from the entrance to the entrance in the order of the glass ribbon from the entrance to the exit. Take the position of the center point of each segment as the surface temperature of each temperature segment, and input the surface temperature of each temperature segment; you can also obtain the surface temperature of each temperature segment through the polynomial fitting curve, that is, based on the actual measured data under stable working conditions ( (See Table 1), the polynomial curve is obtained by fitting (see Figure 13), and the ordinate value (temperature value) of the polynomial curve corresponding to the predetermined position of each sampling point is taken as the surface temperature of each temperature section.

(5) The temperature of the wall surface in contact between the glass ribbon and the tin bath adopts a constant temperature boundary condition, and the temperature is 800K.

The mathematical model established in step three can be used as a working model to simulate a 150t/d medium aluminum glass tin bath.

Verification and analysis of the established working model of glass tin bath:

Based on the established mathematical model to simulate the working state of the glass tin bath, the finite element analysis software is used to input the distance between the glass strip and the entrance of the glass tin bath as a variable into the energy equation, and the digital grid model is iteratively solved and calculated to obtain the tin bath. Temperature values and velocity values of the glass ribbon and protective gas in different areas. The calculation and solution results of the mathematical model established in step three are listed in Table 1-Table 4, Figure 3-Figure 12. Comparative analysis of the mathematical model calculation results and actual process data was conducted to verify whether the established mathematical model can truly simulate the actual working state of the glass tin bath.

1) Comparison of solution result values and measured values (based on sampling at the same location)

Tables 1 and 2 show the comparison results of the glass ribbon temperature and speed calculation results of the medium-aluminum glass tin bath working model and the actual measured temperature values and speed values.

Table 1 Comparison table of surface temperature data of each temperature section on the surface of the glass ribbon

Distance from entrance (m) Actual temperature (℃) Simulation calculation temperature (℃) Temperature difference(℃) Temperature deviation ratio % 1.5 1269 1269 0 0 4 1216 1217 +1 +0.08 7 1168 1166 -2 -0.17 10 1113 1114 +1 +0.09 13 1057 1060 +3 +0.28 16 1014 1013 -1 -0.10 19 968 970 +2 +0.21 twenty two 912 910 -2 -0.22 25 893 895 +2 +0.22 28 874 872 +2 +0.23 31 824 820 -4 -0.49 34 773 771 -2 -0.26 37 738 740 +2 +0.27 40 708 708 0 0

Table 2 Comparison table of speed data of each temperature segment on the glass ribbon surface

It can be seen from Table 1 and Table 2 that the temperature and speed of the glass ribbon are sampled every 3m from the entrance to the exit. Among them, at the same position of the glass ribbon, the temperature value of the glass ribbon calculated using the model is the same as the actual measured temperature value (under working conditions The difference (measured under stable conditions) is between -4℃-4℃, and the temperature deviation ratio is between -0.49%-+0.28%. The glass ribbon speed value calculated using the model and the actual measured speed value (under stable working conditions The difference (measured under normal conditions) is between -0.04m/s-0.06m/s, and the speed deviation ratio is between -2.76%-+3.92%, which meets the general requirement of the model's deviation of ±10%.

Tables 3 and 4 show the comparison between the calculated results of the protective gas temperature and speed of the medium-aluminum glass tin bath working model and the actual measured temperature and speed values.

Table 3 Comparison table of temperature data of each temperature section of protective gas

Distance from entrance (m) Actual temperature (℃) Simulation calculation temperature (℃) Temperature difference(℃) Temperature deviation ratio % 1.5 485 492 +7 +1.44 4 400 400 0 0 7 986 992 +6 +0.61 10 1162 1159 -3 -0.26 13 1112 1108 -4 -0.36 16 1060 1063 +3 +0.28 19 1012 1010 -2 -0.20 twenty two 970 975 +5 +0.52 25 910 908 -2 -0.22 28 887 892 +5 +0.56 31 871 875 +4 +0.46 34 781 777 -4 -0.51 37 732 739 +7 +0.96 40 715 706 -9 -1.26

Table 4 Comparison table of speed data of each temperature section of protective gas

It can be seen from Table 3 and Table 4 that the temperature and speed of the protective gas are sampled every 3m from the inlet to the outlet. Among them, the protective gas temperature value calculated using the model is the same as the actual measured temperature value (under working conditions) at the same position of the protective gas. The difference (measured under stable conditions) is between -9℃-7℃, and the temperature deviation ratio is between -1.26%-+1.44%. The protective gas speed value calculated using the model and the actual measured speed value (under stable working conditions The difference (measured under normal conditions) is between -0.07m/s-0.06m/s, and the speed deviation ratio is between -4.76%-+4.49%, which meets the general requirement of the model's deviation of ±10%.

2) Comparison of graphic images generated by solving calculation results and measured values

The post-processing software CFD-Post is used to display the data in the form of graphics and images of the solution calculation results. According to the post-process solution results, the temperature field distribution of the glass ribbon, the temperature field distribution of the protective gas space and the velocity field distribution of different areas in the tin bath are obtained. , see Figure 3 to Figure 12, which are the temperature and velocity distribution diagrams of the glass ribbon and protective gas on each section simulated under the same conditions as the site. Tables 5 to 10 are a list of the temperature values and speed values of the glass ribbon and protective gas measured on each section under the same conditions and stable working conditions on site (taking the length direction of the tin bath as the x-axis, the width direction as the y-axis, and the height direction is the z-axis).

Compare Figures 3 to 12 with the actual data obtained on site (see Tables 5 to 10) to analyze whether the simulation process using the mathematical model meets the process conditions. The simulation results are calculated by solving the working model of the present invention through simulation software. The temperature and velocity distribution diagram drawn by the simulated data. The actual measured data is obtained by linearly sampling the temperature field and velocity field of the glass ribbon and protective gas in the tin bath on the corresponding cross-section during the glass production process under stable working conditions. The measured data (transmitted from the sensor at the corresponding position to the processor to obtain the corresponding measured data).

Table 5 List of measured temperature values of the glass ribbon on the x-y section under stable working conditions

Table 6 List of measured speed values of the glass ribbon on the x-y section under stable working conditions

Table 7 List of measured temperature values of protective gas in x-y space during top ventilation under stable working conditions

Table 8 List of measured protective gas velocity values in x-y space during top ventilation under stable working conditions

Table 9 List of measured temperature values of protective gas in y-z space during top ventilation under stable working conditions

Table 10 List of measured protective gas velocity values in y-z space during top ventilation under stable working conditions

From the temperature distribution diagram of the x-y section of the glass ribbon in Figure 3, it can be seen that the temperature gradually decreases from the inlet to the outlet, indicating that as the glass liquid forming process proceeds, its surface temperature gradually decreases. The simulated temperature distribution of the glass ribbon is consistent with Table 5 The actual results are close to each other. As can be seen from the temperature distribution diagram of the x-z section of the glass ribbon in Figure 4, at the position corresponding to the x-z plane, except for the position near the outlet, the outer temperature is slightly higher than the central zone temperature, and the temperature in the central zone is higher in other areas. Regarding the temperature outside the tin bath, the simulation results are also basically consistent with the actual measured data trend in Table 5.

From the velocity distribution diagram of the glass ribbon in the x-y section in Figure 5 and the velocity distribution diagram of the glass ribbon in the x-z section in Figure 6, it can be seen that the speed of the glass ribbon in the forward direction first decreases and then increases, mainly due to the rigidity of the glass liquid. It enters the tin bath in a liquid state and has a relatively fast speed. As the glass liquid spreads around to form (forming a glass ribbon), its speed decreases. After passing through the shrinkage section, the glass is formed, and after rapid pulling, its speed further increases. During the forming process, the speed of the middle part of the glass ribbon is higher than the speed of both sides. Since the glass temperature in the middle part is high, the speed of the middle part is higher than the speed of both sides, which makes the thickness of the glass more uniform. The above simulation results are also basically consistent with the trend of the measured data in Table 6.

It can be seen from the temperature distribution diagram of the x-y section of the top ventilation of the protective gas in Figure 7: the temperature at the glass ribbon inlet A1 is the highest, while the protective gas inlet B1 is located at the top of the tin bath, and the temperature of the protective gas entering the tin bath is lower. Therefore, as the distance from the entrance A1 of the glass ribbon increases, the temperature of the protective gas gradually decreases, and the overall temperature distribution of the upper protective gas is lower than the temperature of the protective gas close to the glass ribbon. The trend of the above simulation results is consistent with the measured protective gas in Table 7 The temperature distribution rules on the x-y section are basically the same.

It can be seen from Figure 8 the velocity distribution diagram of the top ventilation of the protective gas in the x-y section and Figure 9 the velocity vector distribution diagram of the top ventilation of the protective gas in the x-y section: the protective gas flows to both sides and both ends, and from the inlet to the outlet, its flow The velocity gradually increases; the velocity field around the air inlet position has the highest velocity when the gas is introduced. As the protective gas diffuses to both sides, its flow velocity decreases. The measured data in Table 8 also reflects the rules drawn from the above simulation results.

It can be seen from the temperature distribution diagram of the y-z section of the top ventilation of the protective gas in Figure 10: the temperature is the lowest at the position where the protective gas is introduced and its vicinity, and the temperature of the bottom glass strip is the highest; the temperature of the upper space of the protective gas is lower than the temperature of the bottom space, and the temperature of both sides above the intermediate temperature. The trend of the above simulation results is consistent with the trend of the measured data in Table 9.

From the velocity distribution diagram of the top ventilation of the protective gas in the y-z section in Figure 11 and the velocity vector distribution diagram of the top ventilation of the protective gas in the y-z section in Figure 12, it can be seen that the speed of the protective gas is maximum when entering the tin bath; The flow speed is smaller than the speed when it is introduced, and the speed is symmetrically distributed with the air inlet as the center. From the measured data results in Table 10, we can draw the same conclusion as the above simulation results.

Based on the above verification conclusion, the results of using the mathematical model established in this embodiment to simulate the working state of the glass tin bath and the actual measurement results of the existing production line show that the temperature and speed distribution patterns of the two are basically consistent. The mathematical model determines that the working state of the glass tin bath is model, and shows that the working model established in this embodiment can simulate the real working state of the glass tin bath.

Example 2: Optimization of working model of glass tin bath

The actual working status of the glass tin bath is affected by many factors, such as the inconsistent speed and temperature on both sides of the glass ribbon in the glass tin bath, the number and layout of the air inlets. In order to simulate the actual working state of the glass tin bath as realistically as possible, the working model of the glass tin bath can be optimized.

A. The actual values of the speed and temperature on both sides of the glass ribbon in the glass tin bath may be inconsistent: Since the boundary conditions set in the simulation of the first embodiment are generally set symmetrically with the center line of the tin bath, the simulation results The data and image display are symmetrical, but the actual situation is: the speed of the glass ribbon on the side with high temperature is relatively fast, and the speed of the glass ribbon on the side with low temperature is relatively slow (the glass temperature is high, the viscosity of the glass ribbon is small, and the glass pulls The resistance is small and the speed is relatively fast).

In view of the deviation between the simulation results and the actual situation, during the optimization process of the simulation, when inputting boundary condition values into the grid model in Step 3 of Embodiment 1, only in (5) the wall surface where the glass ribbon contacts the tin bath When the temperature value is input, the wall temperatures on both sides adopt different constant temperature boundary conditions, that is, there is a difference in the wall temperature values on both sides. This optimized working model can use different velocity and temperature data on both sides of the glass ribbon space as boundary conditions to make the simulation results consistent with the actual values of the glass ribbon velocity and temperature. The simulation results are more referenceable and can also be used as a reference. The simulated numerical values serve as the basis for adjusting various process parameters (see Example 3).

B. Regarding the impact of changes in the number of protective gas inlets on temperature and flow rate.

In order to reduce the total amount of meshing and numerical calculations, and reduce the complexity of meshing and calculations, two protective gas inlets are generally set at the boundary. Although the simulation results of the working model established in this way can reduce the amount of calculations, There may be problems such as the shielding gas speed calculated by the model is smaller than the actual speed, and the temperature distribution of the shielding gas deviates greatly from the actual situation (for example, the temperature in the wide section of the tin bath is higher than the actual temperature).

In view of this situation, the optimized working model is to increase the number of protective gas inlets when establishing the geometric model in step 1, optimize the location and layout of the air inlets, etc., and try to keep the protective gas inlet settings consistent with the actual situation. (For example, the geometric model of Example 1 has 14 air inlets, which are the same as the glass tin bath prototype). At the same time, when establishing the grid model in step 2, the area where the air inlets are located is re-meshed. Generally, the air inlets are selected. The more ports there are, the greater the density of the grid divided by the protective gas space B, which ensures the accuracy and stability of the simulation model while taking into account the amount of numerical calculations. For example, when 2 air inlets are selected, the total number of meshes is 200,000, and when 14 air inlets are selected, the total number of meshes is 250,000. The simulation calculation after the first mesh division is used The time is short, but the error between the simulation results and the actual measured values is large; the second meshing is based on the premise of being consistent with the actual distribution and number of air inlets, although the calculation time of this model is relatively high The calculation time of the first meshed model is long, but it is still within the tolerable calculation amount range, and the calculation results of the second meshed model are compared with the calculation results of the first meshed model. The temperature and speed of the belt and the temperature and speed of the protective gas have small deviations. This optimized working model can make the simulation results consistent with the actual values of the temperature and velocity of the protective gas, and the simulation results are more referential.

If the difference between the calculation results of the mathematical model and the actual measurement data does not meet the model deviation requirements, you can return to step 2 to re-mesh the geometric model to meet the calculation requirements (for example, re-mesh the area where the air inlet is located in B division), you can also return to step three to change the input boundary condition values and re-digitize the grid model to better match the actual working status of the glass tin bath (for example, the change in the wall temperature boundary conditions on both sides of the glass tin bath in A).

Example 3: Application of working model of glass tin bath

This embodiment uses the established and verified working model of the glass tin bath. When there are quality problems or problems with the glass process of the glass plates produced using the existing glass tin bath, the problem can be quickly discovered with the help of the calculation of the working model. Reduce the maintenance cost and difficulty of glass tin bath.

Existing glass tin baths and production overview:

Glass type: medium alumina glass (the mass content of alumina in glass is generally between 4% and 8%);

Production capacity: 150t/d;

Tin bath parameters: the wide section is 24m×5.2m (length×width), the length of the shrinking section is 3m, the width changes linearly, and the narrow section is 10.8m×4.5m;

Protective gas components: nitrogen: 92%, hydrogen: 8%;

Taking the above-mentioned glass tin bath as a prototype and based on the known production process conditions, the working model of the glass tin bath was established using Example 1, where:

Select the standard κ-ε engineering model, energy equation:

Set boundary conditions:

(1) The inflow speed of the molten glass at the entrance A1 of the glass ribbon is 0.16m/s, and the temperature of the molten glass at the entrance A1 of the glass ribbon is 1373.15K;

(2) The outlet temperature of the glass ribbon outlet A2 is 873.15K, and the pressure at the glass ribbon outlet A2 is 5Pa;

(3) The input gas entry speed at the protective gas inlet B1 is 2m/s, the temperature at the protective gas inlet B1 is 673.15K; the outlet pressure at the protective gas outlet B2 is 5Pa, and the temperature at the protective gas outlet B2 is 873.15K.

This production line produces ultra-thin medium-alumina glass. In actual production, when the glass thickness is above 1.1mm, the parameters of the tin bath, the quality and properties of the glass do not change significantly. However, when the thickness of the glass is below 0.7mm, the thickness of the glass varies. The streaks on the surface are significantly increased, and the quality and performance of the glass are reduced.

By comparing the measured data and simulation results, it is found that the simulation result image display (see Figure 3 to Figure 12) is symmetrical for the velocity and temperature distribution on both sides of the glass tin bath, while the actual measurement data display is shown in Table 5 and Table 7 (for Measured data of glass with a thickness of 0.7mm). For example, the data on both sides of the tin bath at positions 4 meters away from the entrance and 16 meters away from the entrance are asymmetrical. Therefore, comparing the simulation results and the actual measured data can be preliminarily analyzed to determine the reasons for the decline in glass quality. The factor is that the velocity and temperature distribution on both sides of the glass tin bath are inconsistent.

After inspecting the entire tin bath, it was found that there was indeed a difference in temperature on both sides of the tin bath. The main reasons for the temperature difference were analyzed: First, due to the relationship between the glass production line and the main wind direction of the area where the production line is located, generally the temperature on the upwind side is opposite. The second reason is due to the alternating seasons of spring, summer, autumn and winter, and the temperature difference caused by different sunlight. The third reason is due to the influence of human factors, such as the temperature on one side of the control room, where there is more human activity, is relatively higher. The above factors have a greater impact on the production of glass with a thickness of less than 0.7mm. This is because when producing glass with a thickness of less than 0.7mm, the thickness difference of the glass is relatively sensitive, the sensitivity of the glass to temperature is also greatly increased, and stripes are easily formed on the glass surface. The inconsistency between mathematical simulation results and actual measured values also illustrates this point.

Solution: Through the above analysis, insulate the outer end of the entire glass tin bath (such as setting up an insulation layer) to make the temperature distribution on both sides of the glass tin bath symmetrical (then adjust and coordinate the parameters of the edge drawing machines on both sides) ), stabilizing glass production. After actual verification, the quality of glass below 0.7mm produced by the improved glass tin bath has been significantly improved.

Example 4: Establishment and application of mathematical model of glass tin bath

For a newly designed glass tin bath, a mathematical model is established to gradually optimize the design plan (for example, the structure and size of the tin bath, heating control plan, etc.), and adjust the boundary condition parameters to determine the parameters required to achieve a suitable process system. The temperature field and velocity field distribution of the glass ribbon and protective gas are used to determine the tin bath design plan.

This embodiment takes the design of a tin bath for low-aluminum glass (the mass content of alumina in glass is generally between 0.5% and 2.5%) with a production capacity of 100t/d as an example. The parameters of the tin bath to be designed are: the wide section is 27m long and 6m (length × width), the length of the contraction section is 3m, the width changes linearly, and the narrow section is 9m × 4.6m;

Protective gas components: nitrogen: 94%, hydrogen: 6%;

Referring to the method of establishing the working model of the glass tin bath in Embodiment 1, a geometric model is established based on the above parameters of the low-aluminum glass tin bath. ANSYS ICEM-CFD software is used to mesh the space of the geometric model, and the mesh is refined in local areas. , a total of about 185,000 grids were divided to establish a grid model, and the standard κ-ε engineering model and energy equation were also selected to establish a mathematical model:

Set boundary conditions (empirical values):

(1) The inflow speed of the molten glass at the entrance A1 of the glass ribbon is 0.16m/s, and the temperature of the molten glass at the entrance A1 of the glass ribbon is 1323.15K;

(2) The temperature at A2 at the exit of the glass ribbon is 853.15K, and the pressure at A2 at the exit of the glass ribbon is 3Pa;

(3) The gas entry speed at the protective gas inlet B1 is 2m/s, the temperature at the protective gas inlet B1 is 673.15K; the pressure at the protective gas outlet B2 is 3Pa, and the temperature at the protective gas outlet B2 is 853.15K.

Use the same method as in Example 1 to establish a mathematical model.

The mathematically simulated temperature distribution is based on the viscosity-temperature curve of the glass composition as the basic boundary condition of the model. Since the composition of the molten glass is stable, the temperature range of glass forming is also fixed, such as the entrance of the glass ribbon when the glass liquid enters the tin bath. The temperatures at position A1 and the tin bath exit (glass ribbon exit position A2) are also fixed. The simulation values obtained using the mathematical model established in this example should be consistent with the designed theoretical values. However, during the simulation process, the distance between the glass ribbon and the entrance was entered as a variable into the above mathematical model. The temperature value at the exit of the tin bath (glass ribbon exit part A2) calculated by simulation was lower than 853.15K. The simulated temperature and theoretical temperature values Inconsistent. Analyzing the reason, this should be caused by the temperature loss outside the tin bath (mainly the heat dissipation of the tin bath body). Therefore, in the design of the new glass tin bath, the electric heating system of the tin bath can be added to ensure the stability of the temperature system in the tin bath. , and when designing the tin bath, the electric heating system should be designed and controlled in zones to facilitate adjustment and ensure the stability of the temperature system.

In addition, when designing a new glass tin bath, you can also refer to the simulation results (such as the forms shown in Figures 3 to 12 in Embodiment 1) and past design experience to further improve the accuracy of the tin bath design.

Example 5: Optimizing glass production process based on glass tin bath working model/mathematical model

For the fixed glass tin bath (including the existing glass tin bath and the newly designed glass tin bath), using the working model (such as Embodiment 1) or mathematical model (such as Embodiment 4) established based on the glass tin bath, through During the simulation process, change the boundary conditions input into the grid model to optimize the glass production process, for example, change the glass molten temperature and glass molten inflow velocity conditions at the glass ribbon inlet A1, and change the gas inlet velocity at the protective gas inlet B1 The boundary conditions are equal to each other, and the mathematical model of changing parameters is used to calculate and solve (for the calculation and solution process, please refer to Step 4 of Embodiment 1), and the simulation results are obtained (for the form of the simulation results, please refer to Figures 3 to 12 of Embodiment 1. The glass ribbon and protective gas shown in Figure 12 are Temperature and velocity distribution diagram on each section). Compare and analyze multiple sets of simulation results, and select the process parameters corresponding to the set of simulation results that can obtain the best glass quality as the optimized glass production process. It can also provide guidance for the technical transformation of the tin bath in the existing production line and better It meets the production and forming requirements of different types of glass, reduces the impact of variety changes on the tin bath, improves the adaptability of the tin bath, and improves the efficiency of the production line.

The above are only specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any person familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed in the present invention. should be covered by the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims.

Claims (8)

1. A method for establishing a working model of a glass tin bath, which is characterized by including the following steps: Step 1: Establish a geometric model: Use computer modeling software to use the glass tin bath as a prototype to establish a geometric model including the glass strip space and the protective gas space; Step 2: Establish a grid model: Use finite element analysis software to divide the glass strip space and protective gas space in the established geometric model into grids respectively to form a grid model; Step 3: Establish a mathematical model: Based on the composition and properties of the glass ribbon and protective gas, combined with the glass production process, select an engineering model algorithm that simulates the working state of the glass tin bath and the energy equation therein, and determine the space and energy equation of the glass ribbon based on this energy equation. Protect the boundary conditions of the boundary parts of the gas space, and then input the determined numerical values of the boundary conditions into the grid model to establish a digital grid model. The digital grid model and energy equation form a mathematical model for calculation, as a glass tin bath working model; In step three, the boundary parts of the glass ribbon space include the glass ribbon entrance part, the glass ribbon exit part, the glass ribbon surface part and the wall part where the glass ribbon contacts the glass tin bath, and the boundary parts of the protective gas include the protective gas inlet. location and protective gas outlet location; The boundary conditions of the glass ribbon inlet and the protective gas inlet are both temperature and velocity. The boundary conditions of the glass ribbon exit and the protective gas outlet are both pressure and temperature. The surface of the glass ribbon and the wall where the glass ribbon contacts the glass tin bath The boundary conditions of the parts are all temperature; The boundary condition values input in step 3 are: the glass liquid temperature value and the glass liquid inflow velocity value at the glass ribbon entrance (A1), the glass ribbon temperature value and glass ribbon pressure value at the glass ribbon outlet (A2), and the protective gas The protective gas entry velocity value and protective gas temperature value at the inlet (B1), the protective gas pressure value and protective gas temperature value at the protective gas outlet (B2), the wall temperature value of the glass ribbon in contact with the glass tin bath, and the glass The temperature value of the belt surface part (A3); The temperature distribution on the surface of the glass ribbon adopts the slow cooling temperature system. The surface of the glass ribbon is treated according to the constant temperature moving surface. According to the order of the glass ribbon from the entrance of the glass tin bath to the exit of the glass tin bath, it is divided into various types according to the distance between the glass ribbon and the entrance of the glass tin bath. For the temperature section, take the surface temperature at the center point of each section as the input boundary condition value for each temperature section; or fit a polynomial curve based on the measured data of the surface temperature of the glass ribbon under stable working conditions, and take each predetermined sampling point. The temperature value on the ordinate of the polynomial curve corresponding to the position is used as the input boundary condition value for each temperature segment; The wall temperature of the glass ribbon in contact with the glass tin bath adopts the same constant temperature boundary condition, or the wall temperatures on both sides of the glass tin bath adopt different constant temperature boundary conditions. 2. The method for establishing a working model of a glass tin bath according to claim 1, characterized in that the grid division adopts a hexahedral structure. 3. The method for establishing a working model of a glass tin bath according to claim 1, characterized in that the boundary condition value is a temperature boundary condition value of the surface of the glass ribbon. 4. The method for establishing a working model of a glass tin bath according to any one of claims 1 to 3, characterized in that it also includes a model optimization step: inputting the energy of the mathematical model using the distance between the glass ribbon and the entrance of the glass tin bath as a variable. In the equation, the digital grid model is iteratively solved and calculated to obtain the temperature and velocity values of the glass ribbon and protective gas in different areas of the glass tin bath; the mathematical model calculation results and the actual measurement data are compared and analyzed. If the two If the difference between the two is within the predetermined deviation range, the mathematical model is determined to be a working model of the glass tin bath that can truly simulate the working state of the glass tin bath; otherwise, optimize the established mathematical model and return to step 2 to re-grid. Or return to step three to change the boundary condition values so that the working conditions of the glass tin bath can be simulated realistically. 5. The method for establishing a working model of a glass tin bath according to claim 4, characterized in that the re-grid refers to grid densification to reduce deviations, or grid thinning to meet normal calculation requirements. 6. The method for establishing a working model of a glass tin bath according to any one of claims 1 to 3, characterized in that in step one, the parameters of the glass tin bath prototype include: the wide section size and shrinkage of the internal space of the glass tin bath. The segment size, narrow strip size, area location of the edge drawing machine and area location of the air inlet; the geometric model parameters of the glass ribbon space and protective gas space are the same as the parameter values of the glass tin bath prototype. 7. The method for establishing a working model of a glass tin bath according to claim 6, wherein the region where the air inlet is located includes the number of air inlets and their distribution. 8. The method for establishing the working model of the glass tin bath according to any one of claims 1 to 3, characterized in that the glass ribbon space in the geometric model is divided into the area where the edge drawing machine is located and the general area. Step 2 is based on the normal The calculation requires uniform grid division of the general area of the glass ribbon space, and a denser grid division of the area of the edge drawing machine; the protective gas space in the geometric model is divided into the area where the air inlet is located and the general area. Step 2: Carry out uniform meshing for the general area of the protective gas space in accordance with the requirements of normal calculations, and conduct a denser meshing for the area where the air inlet is located.