CN111961776A - Thermocouple position mapping method for corner area of blast furnace hearth lining - Google Patents

Abstract

The invention discloses a thermocouple temperature mapping method in the corner area of a blast furnace lining. Through the numerical simulation of the two-dimensional/three-dimensional heat transfer process of the blast furnace hearth lining, the temperature distribution of the blast furnace lining was obtained; the isotherm of the lining corner area was drawn, and then the temperature measurement data of the thermocouples arranged near the corner area of the hearth lining were measured. Move along the isotherm to any heat flow line in the corner area to realize the mapping of thermocouple temperature measurement data on any heat flow line in the corner area. The invention can improve the utilization rate of the thermocouple temperature measurement data in the hearth area, provide basic data for one-dimensional heat transfer calculation in the corner area, and provide technical support for realizing the online prediction of the erosion situation in the corner area.

Description

A method for mapping the position of thermocouples in the corner area of blast furnace hearth lining

technical field

The invention belongs to the field of online prediction of lining erosion in blast furnace hearth, and particularly relates to a method for mapping the position of a thermocouple in a hearth area.

Background technique

The erosion condition of blast furnace hearth lining directly determines the service life of blast furnace, so the prediction of its erosion condition is the focus and difficulty of blast furnace service life research. At present, the online prediction method for the erosion of blast furnace lining is to simplify the heat transfer process of the hearth lining into a one-dimensional heat transfer model. Based on the Fourier heat conduction law, according to the temperature data of two thermocouples in the same heat flow direction of the furnace lining, the calculation is carried out. The position coordinates of the hot surface of the cylinder lining, and then the erosion or slagging of the lining can be obtained.

However, the temperature in the corner area is affected by the heat transfer process of the side and bottom linings, and its temperature changes significantly in the radial and height directions, so the heat flow lines from the furnace shell to the lining hot surface extend irregularly in the radial and height directions. , as shown in Figure 1; in addition, affected by the flow of molten iron in the hearth, the floating height of the dead column, etc., the corner area is prone to erosion, and the continuous change of the thickness of the lining leads to a significant change in the temperature distribution in this area, resulting in heat flow in the corner area. The line also changes accordingly. For corner areas, it is difficult to ensure that there are 2 embedded thermocouples on the same heat flow line. Therefore, how to obtain two temperature data on the same heat flow line is the key to the online prediction of the erosion state of the corner area of the hearth lining by applying the one-dimensional heat transfer model.

SUMMARY OF THE INVENTION

In order to achieve the accurate acquisition of the temperature in the corner area of the blast furnace hearth lining, the present invention proposes a method for mapping the position of thermocouples in the corner area of the blast furnace hearth lining, making full use of the thermocouple data to draw the heat flow line in the corner area, thereby improving the one-dimensional heat transfer based on Reliability of prediction of blast furnace lining erosion morphology.

For realizing the above-mentioned technical purpose, the technical scheme provided by the present invention is as follows:

The present invention is a method for mapping the position of a thermocouple in a corner area of a blast furnace lining, comprising the following steps:

According to the flow pattern of molten iron inside the hearth and the structure and material of the inner lining of the hearth, a numerical simulation model is established, and the fixed solution conditions are determined.

Establish lining isotherm according to lining temperature distribution;

According to the temperature measurement data of the side and bottom thermocouples, move the thermocouple to the corresponding heat flow line in the corner area along the isotherm where the temperature measurement data is located to complete the mapping of its position.

In practical application, geometric modeling and mesh division of the hearth area (including furnace lining) are carried out to determine the numerical simulation model and solution conditions for the flow and heat transfer process of molten iron in the hearth, and the numerical simulation calculation is carried out to obtain the temperature distribution of the furnace lining.

Further, the numerical simulation model includes: a mathematical model of molten iron flow and heat transfer and fluid-solid coupling.

The invention provides a method for mapping the position of thermocouples in the corner area of a blast furnace lining. The acquisition and drawing of the isotherm of the hearth lining includes the following steps: extracting grid node temperature data obtained by numerical simulation, and using an interpolation method to map the temperature data and corresponding positions. Interpolate; based on the numerical simulation and the interpolated position and temperature data, draw the isotherm where the thermocouple temperature measurement data is located, and within a small temperature difference range, draw as many isotherms as possible to form isotherm clusters in the lining area.

Further, the step of obtaining denser temperature data by linear interpolation is: according to the number of grids in the corner area, using a linear interpolation method to calculate the data of discrete points between grids.

In practical applications, based on the full-field temperature distribution in the corner area, combined with the sidewall and bottom thermocouple temperature measurement data, the temperature field is divided into N temperature intervals (including thermocouple temperature measurement data), and the corner area isotherm cluster is constructed. The N is greater than or equal to 15; preferably greater than or equal to 20.

In practical application, the shallow thermocouple in the lining close to the furnace shell or any position of the shallow lining layer is used as the starting point, and the vertical lines of the isotherm are made in turn to construct the heat flow line from the shallow lining thermocouple.

The invention relates to a method for mapping the position of thermocouples in the corner area of a blast furnace lining. The process of mapping the position of thermocouples includes the following steps: moving the thermocouple temperature measurement data to the target heat flow line in the corner area according to the isotherm where the thermocouple temperature data is located. .

In practical application, the thermocouple data that is not on the heat flow line is moved to the corresponding heat flow line in the corner area through the isotherm line equal to its temperature measurement value to complete the mapping, and obtain the coordinates of the mapped thermocouple for the follow-up. Dimensional heat transfer calculations.

The invention relates to a method for mapping the position of thermocouples in the corner area of a blast furnace lining. The target heat flow line includes two thermocouple data; the above two thermocouple data are composed of an actual thermocouple temperature measurement data and the mapped thermocouple data. , or both data are mapped thermocouple data.

Compared with the prior art, the advantages of the present invention are:

1) Improve the utilization rate of thermocouple temperature measurement data with lining arrangement;

2) The accuracy of the heat flow line drawing in the corner region is improved, which provides support for the application of the one-dimensional heat transfer model in the prediction of erosion in the corner region.

Description of drawings

Accompanying drawing 1 is the schematic diagram of hearth lining heat flow line

Accompanying drawing 2 is the thermocouple position mapping flow chart in the embodiment of the present invention;

Accompanying drawing 3 is the taphole side (including lining) structure and thermocouple position of blast furnace hearth;

Accompanying drawing 4 is the temperature distribution of tap hole side hearth lining in embodiment 1;

Figure 5 is the isotherm and heat flow diagram of the corner area on the tap hole side.

Detailed ways

The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

1) The schematic diagram of the installation position of the thermocouple on the tap hole side of a blast furnace is shown in Figure 3. A total of four layers of thermocouples are arranged on the side, which are marked as G, H, J, K, and L respectively, and a layer of thermocouples (M layer) is arranged on the bottom.

2) Numerical simulation of the flow and heat transfer process of molten iron in the blast furnace hearth and the fluid-solid coupling between the molten iron and the lining is carried out by using the operating parameters and structure of the blast furnace, and the temperature distribution of the inner lining and the molten iron in the hearth is obtained. Mathematical models of blast furnace hearth structure and molten iron flow heat transfer and fluid-solid coupling are as follows:

The governing equation of flow heat transfer in the hearth is as follows:

Continuity Equation:

Momentum equation:

For the turbulent flow of molten iron, the standard k-ε turbulence model is used.

Energy equation:

In the formula, ρ is the density of molten iron in the hearth, kg/m ³ ; u is the velocity of molten iron in the x direction, m/s; v is the velocity of molten iron in the y direction , m/s. p is the pressure of molten iron, Pa; μ is the dynamic viscosity of molten iron, Pa·s; g is the acceleration of gravity, m/s ² ; Si ( _i =x, y) is the resistance generated by the fluid flowing through the dead stock column. k is the thermal conductivity of molten iron, W/(m·K); c _p is the specific heat capacity of molten iron at constant pressure, J/(kg·K), and T is the temperature of molten iron, K .

The source term Si ( _i =x,y) in the momentum equations (2) and (3) is calculated using the resistance of the fluid flowing through the porous medium The equation, that is, the Ergen equation is calculated, taking the X direction as an example, as shown in formula (5):

In the formula, d _p is the average particle diameter of the charge, m. The first term on the right side of the above equation is the viscous loss term, and the second term is the inertial loss term. The corresponding viscous loss coefficient 1/α and inertial loss coefficient C ₂ in each direction are calculated as follows:

为颗粒形状系数；ε为炉缸中处理为多孔介质的死铁层或焦炭层的孔隙率；In the formula,

is the particle shape coefficient; ε is the porosity of the dead iron layer or coke layer treated as porous media in the hearth;

For the fluid-solid coupling model, in the actual numerical simulation process, all the walls in direct contact with molten iron are set as It is implemented for the fluid-structure interaction boundary, which ensures that the solver uses the data of the adjacent grids of the boundary to calculate the distance between the lining and the molten iron. The heat transferred, denoted by Q _c . The temperature distribution within the furnace lining is then calculated using Fourier's law of heat conduction (equation (6)).

In the formula, Q _c is the heat flow through the side wall calculation area, W; A is the cross-sectional area of the side wall calculation area perpendicular to the heat flow direction, m ² ; r is the distance from a point in the lining to the center of the furnace, m; H is the side The height of the wall calculation area, m; k is the thermal conductivity, W/(m·K).

The model solution conditions are as follows:

(1) Inlet boundary: the free plane of molten iron in the hearth is set as the velocity inlet, which is obtained by converting the uniform tap rate of the tap hole;

(2) Outlet conditions: a pressure outlet is used at the hearth outlet, and a constant pressure value is set;

(3) Outer surface of the sidewall and bottom of the hearth: Convective boundary, the convective heat transfer coefficient is converted from the temperature and flow rate of the cooling water on the sidewall and bottom of the hearth.

In addition, the refractory surface at the top of the hearth was set as an insulating wall, and all solid walls were set as no-slip boundary conditions.

Finally, the temperature distribution of the hearth lining under certain erosion conditions obtained by numerical simulation is shown in Figure 4.

3) Extract the temperature of grid nodes in Fig. 4, and use the interpolation method to refine the results; the grid nodes on the isotherm of the hearth obtained by numerical simulation and the coordinates of discrete points obtained after refinement are shown in Table 1 (with no iron casting) 575K isotherm on the mouth side, -6.60～-6.50m position as an example).

Table 1 Grid nodes and discrete point coordinates of taphole on 575K isotherm line (part -6.5～-6.4)

In Table 1, the underline marks are the grid node coordinates, and the others are the discrete point coordinates obtained after refined processing using the interpolation method. Similar to obtaining Table 2, the interpolation method is also used for other layers of the hearth lining to obtain the positions of grid nodes on other isotherms and the positions of discrete points after refined processing, so as to prepare for the drawing of heat flow lines in the next step.

4) Drawing of heat flow lines in hearth lining

Use the thermocouple and the corresponding position coordinates and temperature data of the refined discrete points to draw the heat flow line. The drawing method is: connect the discrete points with the same temperature in the previous step to form an isotherm. Select the position of the super-shallow thermocouple or any position of the shallow lining as the starting point of the heat flow line, and make a vertical line to the isotherm of the inner lining through this point, and the vertical foot is the discrete point that constitutes the heat flow line; Continue to make the vertical line of the inner layer isotherm to get all the discrete points that make up the heat flow line, as shown in Figure 5.

5) Mapping of thermocouple positions

Extract the positions of the original temperature measurement points, discrete point coordinates and their temperatures of the G, H, J, K, L, and M layers of thermocouples in Figure 3. The thermocouple data is shown in Table 2 (take the tap hole side as an example),

Table 2 The position and temperature measurement data of the thermocouple on the tap hole side

Based on the obtained heat flow line and the temperature measurement value of the inner thermocouple, the mapping point of the deep thermocouple on the heat flow line is obtained. In this example, if point R in the lining is the starting point of a heat flow line, the mapping position of the deep thermocouple (-6.287m, 3.38m, 543.6K) at the position of point P in the G layer on the heat flow line is shown in the middle point in Figure 5 As shown in Q (-5.785m, 1.628m, 543.6K); if the surface thermocouple is used as the starting point of the heat flow line, the specific position coordinates of the other deep thermocouples are shown in Table 3 (take the tap hole side as an example) .

Table 3 The mapping position of the thermocouple temperature T _D in the corner area of the deep lining of the tap hole side hearth

layers X/m Y/m T_D/K H -6.34295 3.170509 509.55 J -6.29877 2.944617 475.47 K -5.42282 3.16709 458.31 L -5.34838 3.087364 441.15 M -4.67283 3.586306 543.63

Claims (10)

1. a blast furnace lining corner area thermocouple position mapping method, is characterized in that: comprise the following steps: According to the flow pattern of molten iron inside the hearth and the structure and material of the inner lining of the hearth, a numerical simulation model is established, and the fixed solution conditions are determined. The isotherm distribution of the lining is obtained according to the temperature distribution of the lining; According to the temperature measurement data of the side and bottom thermocouples, move the thermocouples along the isotherm to the corresponding heat flow lines in the corner area to complete the mapping of their positions. 2. a kind of blast furnace lining corner area thermocouple position mapping method according to claim 1, is characterized in that: carry out geometric modeling and grid division to hearth area, determine hearth molten iron flow heat transfer process numerical simulation model And the solution conditions are determined, and numerical simulation calculation is performed to obtain the temperature distribution of the furnace lining; the hearth area includes the furnace lining. 3 . The method for mapping the position of thermocouples in the corner area of a blast furnace lining according to claim 1 , wherein the numerical simulation model comprises: a mathematical model of molten iron flow and heat transfer and fluid-solid coupling. 4 . 4. a kind of blast furnace lining corner area thermocouple position mapping method according to claim 1 is characterized in that: the acquisition and drawing of described hearth lining isotherm comprises the following steps: extracting the grid node temperature obtained by numerical simulation Based on the numerical simulation and the interpolated position and temperature data, the isotherm of the thermocouple temperature measurement data is drawn. 5. The method for mapping the position of thermocouples in the corner area of a blast furnace lining according to claim 1, wherein the temperature distribution of the inner lining includes the temperature distribution of the corner area of the inner lining, which is obtained by linear interpolation than the existing grid nodes. More dense temperature data. 6. a kind of blast furnace lining corner area thermocouple position mapping method according to claim 5, is characterized in that: the step of linear interpolation obtaining denser temperature data is: according to corner area grid quantity, utilize linear interpolation method to calculate net Data for discrete points between grids. 7. a kind of blast furnace lining corner area thermocouple position mapping method according to claim 5, it is characterized in that: based on the corner area full-field temperature distribution, in conjunction with sidewall and bottom thermocouple temperature measurement data, the temperature field is divided into N temperature intervals, and corner area isotherms are constructed. The N is greater than or equal to 15; preferably greater than or equal to 20; there must be an area within the N temperature intervals that contains thermocouple temperature measurement data. 8. a kind of blast furnace lining corner area thermocouple position mapping method according to claim 1, its 1]] 5 is characterized in that: the shallow thermocouple close to the furnace shell in the inner lining or any position of the inner lining shallow layer as Starting from the starting point, make the vertical lines of the isotherm in turn, and construct the heat flow line from the lining shallow thermocouple to the lining hot surface. 9. a kind of blast furnace lining corner area thermocouple position mapping method according to claim 5 is characterized in that: described thermocouple position mapping process comprises the following steps: according to the isotherm where thermocouple temperature data is located, the thermocouple is measured The temperature data is moved to the target heat flow line in the corner area; Move the thermocouple data that is not on the heat flow line to the corresponding heat flow line in the corner area through the isotherm with the same temperature measurement value, complete the mapping, and obtain the coordinates of the mapped thermocouple for subsequent one-dimensional heat transfer calculation. . 10. A method for mapping the position of thermocouples in a corner area of a blast furnace lining according to claim 1, wherein the target heat flow line includes two thermocouple data; the above two thermocouple data are measured by an actual thermocouple temperature data and the mapped thermocouple data, or both data are mapped thermocouple data.

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