JP5994086B2 - Deformation calculation method for brick structure - Google Patents

Description

  The present invention relates to a method for calculating a deformation amount of a brick structure such as a coke oven by structural analysis.

  An example of the brick structure is a coke oven (a chamber type coke oven). FIG. 1 is a schematic perspective view of a coke oven, and FIG. 2 is a schematic perspective view of a brick structure inside the furnace body. As shown in FIG. 1, the coke oven has a number of carbonization chambers 20 for carbonizing coal into coke and a number of combustion chambers 21 for burning coal heating fuel gas alternately in the furnace width direction. Arranged and configured. As shown in FIG. 2, the carbonization chamber 20 is a space partitioned by a furnace wall 22 with respect to the combustion chamber 21, and the combustion chamber 21 is a brick-joint structure having a flue 23 through which combustion gas passes. The furnace body bricks of the combustion chamber 21 and the carbonization chamber 20 are covered with hardware (not shown), and the hardware is supported by the backstay 24, which is arranged on the top of the furnace and the lower part of the furnace (not shown). To hold the furnace body. The carbonized coke is extruded out of the furnace by an extruder 25.

Coke ovens, which are brick structures, are subject to extrusion load and heat load during many years of operation, and cracks in joints and bricks gradually develop. Even when the tension rod breaks and the furnace tightening is released, the brick structure is loosened, cracks occur in the joints and bricks, and when damage progresses, the entire furnace wall is deformed. As this deformation progresses, it will be necessary to carry out a large-scale repair of transshipment of bricks, so it is extremely important to understand the degree of deformation of the coke oven.
Conventionally, in order to grasp the degree of deformation and damage of a coke oven, the following methods have been proposed.
Patent Document 1 proposes a method for measuring the distance between furnace walls in the longitudinal direction at an arbitrary height of the carbonization chamber and comparing the distance between furnace walls at the time of design to determine the amount of carbon adhesion and the amount of brick defects. Has been.

In Patent Document 2, the distance measurement result to the wall surface of the carbonization chamber by the electromagnetic distance meter is corrected using the extrusion ram movement trajectory to calculate the absolute shape of the wall surface of the carbonization chamber. A method has been proposed in which the absolute shape of the wall surface is measured and the carbon adhering state or the worn state of the wall surface is quantitatively determined from the change in the absolute wall shape immediately after the repair is completed.
Patent Document 3 proposes a method in which an observation lance is inserted into a combustion chamber of a coke oven and a wall surface of the combustion chamber is imaged with the observation lance to obtain a defect portion image.

JP 2007-332382 A JP 2006-36958 A JP 2002-226862 A

  As described above, several methods for grasping the degree of deformation and damage of the coke oven have been proposed, and the method is mainly measurement with a distance meter or imaging with an observation device. However, in the method of Patent Document 1, when the coke oven is aged, the reference position may be shifted from that at the time of design, and it is not always accurate to use the distance at the time of design as a reference. Moreover, in the method of patent document 2, it is necessary to measure the absolute shape of the wall surface every time after repairing the wall surface, which is a laborious method. Further, in the method of Patent Document 3, it is determined from imaging, and it may be difficult to quantitatively grasp.

  Accordingly, an object of the present invention is to solve the above-described problems of the prior art and to provide a calculation method capable of accurately calculating the deformation amount of a brick structure with little effort.

The inventors of the present invention have previously made a machine for a brick structure having two or more bricks including joints, the bricks and joints having a structure equivalent to the bricks and joints of the brick structure to be analyzed. It has been found that the amount of deformation of a brick structure such as a coke oven can be accurately calculated by obtaining the physical property value and performing structural analysis using the mechanical property value.
The present invention has been made based on such findings, and the gist thereof is as follows.

[1] A method of calculating a deformation amount of a brick structure by modeling a shape of the brick structure, performing a structural analysis by a finite element method by giving mechanical property values and boundary conditions of the brick structure, The object is a coke oven, and the mechanical properties of the brick structure are two or more bricks (a) including joints (b). The bricks (a) and joints (b) are brick structures. The deformation | transformation amount calculation method of the brick structure characterized by using the value calculated | required previously by the test using the brick structure (A) which has a structure equivalent to a brick and a joint.
[2] In the deformation amount calculation method of [1] above, if the principal stress calculated in the structural analysis exceeds the tensile strength, it is determined that a crack will occur in the direction perpendicular to the principal stress direction, and in the direction perpendicular to the crack, A method for calculating a deformation amount of a brick structure, wherein a constitutive law of tensile behavior to be softened is applied .

  According to the present invention, the brick (a) is composed of two or more bricks including the joint (b), and the brick (a) and joint (b) are equivalent to the brick and joint of the brick structure to be analyzed. For the brick structure (A) having the following structure, the mechanical property value is obtained in advance, and the mechanical property value is used to perform the structural analysis, thereby reducing the amount of deformation of the brick structure such as a coke oven with less effort. It can be calculated well. Furthermore, in the structural analysis, the amount of deformation of the brick structure can be calculated more accurately by including a characteristic that softens when the main stress of the brick structure exceeds the tensile strength.

Schematic perspective view of chamber furnace coke oven Schematic perspective view of the brick structure inside the furnace body of a chamber-type coke oven In this invention, explanatory drawing which shows an example of the brick structure used in order to obtain | require a mechanical property value Drawing which shows an example of the constitutive law in the compression behavior used by this invention Drawing which shows an example of the constitutive law in the tensile behavior used by this invention The flowchart of the deformation amount calculation method of the brick structure of the present invention Explanatory drawing which shows an example of the arithmetic system (deformation amount calculation apparatus) which is provided for implementation of the method of the present invention Drawing of coke oven analysis model in the embodiment

Hereinafter, a case where the brick structure is a coke oven will be described as an example.
Since the coke oven is hot and the space in which sensors can be inserted and installed is limited, it is appropriate to apply a structural analysis technique to grasp the amount of deformation of the coke oven. I thought. In other words, in this method, the area of the coke oven where the amount of deformation is to be calculated (furnace body part including the brick structure) is modeled, and the mechanical properties and boundary conditions of that area are given to analyze the structure using the finite element method. To calculate the deformation amount of the specific region of the coke oven. However, the coke oven is a structure that mainly combines bricks and joints, and due to the non-uniformity of the material, local damage behavior such as joint breaks and cracks in bricks can be seen, and prediction of damage to the coke ovens It is difficult. Even when considering a single coke oven, it is almost impossible to handle and evaluate the behavior of bricks and joints separately.

Therefore, in the present invention, when calculating the deformation amount of the coke oven by structural analysis, as a mechanical property value of the coke oven, a value obtained in advance using a brick structure composed of two or more bricks including joints between them is used. I thought about using it. The degree of deformation of a brick structure greatly depends on the size, material, presence of dowels, joint thickness, etc., so the mechanical properties are evaluated with a brick structure in which two or more bricks and joints are integrated. However, it is considered that using the mechanical properties for structural analysis is effective in accurately calculating the deformation amount of a brick structure such as a coke oven. FIG. 3 shows an example of the brick structure A for which the mechanical properties are obtained in advance as described above. The brick structure A is composed of two bricks a including a joint b, and each brick a has a dowel c (and a dowel hole). Brick a and joint b have the same structure as the brick and joint used in the coke oven (brick structure) to be analyzed (brick size, material, presence and configuration of dowels, joint thickness, etc.) Have. Here, the bricks a and joints b have the same configuration as the bricks and joints used in the coke oven (brick structure) to be analyzed. It is the same as the brick structure, and the size and thickness of the brick (including the presence / absence and configuration of the dowel) and the joint thickness are representative of the brick structure in the region (that is, the brick structure in the region to be analyzed) The most commonly used brick size and joint thickness). This is because the shapes and dimensions of the bricks used in one coke oven are not all the same, and the joint thickness is generally partially changed.
The brick structure A may be composed of three or more bricks a including the joint b therebetween. However, from the viewpoint of using a “brick structure A” that can be easily tested technically and economically, the number of bricks a constituting the brick structure A is about 10 at most. Appropriate, usually about 2-3.

  The mechanical property values required for the brick structure A include, for example, density, elastic modulus, Poisson's ratio, compressive strength, tensile strength, and the like. In addition, when the object is a brick structure that is used at a high temperature such as a coke oven and has a large temperature change, it is desirable to consider the coefficient of thermal expansion and the temperature dependence of each property. It is preferable to include mechanical properties at temperature. If necessary, it is desirable to perform temperature analysis by giving temperature properties (thermal conductivity, specific heat, etc.). These mechanical property values are mainly determined by performing necessary tests such as a compression test and a tensile test on the brick component A.

Furthermore, it is desirable to determine the constitutive law in the compression behavior and the tensile behavior from the above mechanical property values, and use this for the structural analysis. An example of the constitutive law is shown in FIGS. FIG. 4 shows a constitutive law for compression behavior, and FIG. 5 shows a constitutive law for tensile behavior. In this example, the stress-strain relationship is determined by using the ultimate compressive strain εu and the ultimate tensile strain εm in addition to the elastic modulus Eo, the compressive strength fc, and the tensile strength ft as mechanical property values. Here, the ultimate compressive strain εu is a strain corresponding to the maximum compressive stress value, and the numerical value varies depending on the model of the constitutive law. For example, in the case of the model of FIG. It is decided in the range. Further, the ultimate tensile strain εm is a tensile strain corresponding to at the time of fracture, and its numerical value varies depending on the model of the constitutive law. For example, in the case of the model of FIG. It is decided.
As shown in FIG. 4, it is assumed that the compressive behavior is such that the strain ε increases as the compressive stress σ acting increases, and the material collapses when reaching the limit. In addition, as shown in FIG. 5, the tensile behavior increases as the tensile stress σ increases until the tensile strength ft is reached, as shown in FIG. When the tensile strength ft is reached, the material cracks, and even if tension is applied, only the strain ε increases, and when the limit is reached, the material breaks.
According to the constitutive law in the tensile behavior, it is desirable to take into account the property of cracking and softening when the tensile strength exceeds ft.

In the present invention, the shape of the coke oven (brick structure) is modeled, the structural analysis is performed by the finite element method, and the amount of deformation of the coke oven is calculated. This is performed using a mechanical property value obtained in advance (more preferably, a constitutive law determined from this mechanical property value).
FIG. 6 shows a flowchart of the method of the present invention. In the method of the present invention, first, a region (furnace body portion including a brick structure) for which the amount of deformation is to be calculated by analysis is selected from the target coke oven, and the region is modeled. The region to be analyzed is, for example, one combustion chamber or a ceiling portion. In this shape modeling, for example, the shape is created using an appropriate preprocessor, and a calculation mesh is created.

Next, compression determined based on the mechanical property values of the furnace body part (brick structure part) and incidental structures (backstays and hardware that restrain the brick structure) included in the shape model, more preferably based on the mechanical property values Enter constitutive laws for behavior and tensile behavior. The constitutive rules of the mechanical property value, compression behavior, and tensile behavior of the furnace body portion (brick structure portion) are as described above.
Also, since coke ovens are used at high temperatures, temperature properties such as thermal expansion coefficient and thermal conductivity are also input.

  Furthermore, temperature conditions, constraint conditions, and external forces are input as initial conditions and boundary conditions necessary for the analysis. Although the temperature condition may be handled isothermally during steady operation, for example, (i) When temporary operation is stopped during repair, the temperature of the kiln rises to about 1200 ° C after the temperature drops by several hundred degrees (Ii) the temperature distribution is not uniform and the temperature may be partially low (for example, only the edge is low in temperature). In addition, the constraint condition is a constraint condition by an incidental structure or another furnace body part that holds the furnace body part (brick structure part) to be analyzed at the position. In particular, as described above, in the coke oven, the brick structure is constrained by hardware or a backstay, and what kind of force is used for tightening (including the case where the tightening force is loosened for some reason). Necessary for calculation. In addition, during the carbonization of coal, the coal expansion pressure acts on the furnace wall, and during the coke extrusion, an extrusion load is applied to the furnace wall, and these actions are also considered as external forces. In addition, the temperature conditions, restraint conditions, and external force as described above are determined immediately after charging coal in the kiln, whether it is at the end of dry distillation, whether it is during coke extrusion, whether it is repaired, Since it changes depending on the operating conditions such as whether or not it is an empty kiln, temperature conditions, restraint conditions, and external force are determined according to these differences.

  After inputting the above items, the structural analysis of the coke oven by the finite element method is performed. The structural analysis by the finite element method is executed on a computer using a general-purpose structural analysis program based on the input of each item as described above. In this structural analysis, it is preferable to determine the occurrence of a crack and calculate the deformation amount in consideration of the softening of the member due to the crack. That is, if the calculated principal stress exceeds the tensile strength, it is determined that a crack will occur in the direction perpendicular to the principal stress direction, and the crack is generated as an elastic body until the occurrence of the crack or in the direction parallel to the crack, but the direction perpendicular to the crack The constitutive law of the tensile behavior to be softened is applied. Since the amount of deformation is significantly increased due to the occurrence of cracks, it is important to determine cracks and consider the softening properties after cracks.

  After the solution is obtained by repeated calculations, the deformation of the coke oven is output. The output method is arbitrary. For example, even a visualization display obtained by deforming a coke oven shape model, or an iso-deformation diagram distinguished by color on a coke oven shape model, as in an XY graph Output may be sufficient. Moreover, you may display other parameters, such as the stress obtained by analysis. It may be implemented using a suitable post processor.

An example of an arithmetic system (calculation device) provided for implementation in the present invention is shown in FIG. This computing system (calculation device) includes an input unit 1 for inputting physical property values (mechanical properties, temperature physical properties) and initial conditions / boundary conditions (temperature conditions, constraint conditions, external force), and input physical property values (mechanical physical properties, The calculation processing unit 2 performs structural analysis by the finite element method based on the temperature physical properties) and the initial conditions / boundary conditions (temperature conditions, constraint conditions, external force), and calculates the deformation amount. An output unit 3 is provided for outputting the deformation amount and the like.
The present invention is not limited to a coke oven, but can be applied to all types of brick structures including a heating furnace and a converter.

  In an aging furnace-type coke oven, a certain kiln was made empty and the furnace lid was opened for maintenance. Due to operational effects, the furnace lid opening time became longer, and when the normal temperature was about 1200 ° C., the temperature dropped to about 800 ° C. When the temperature was raised again to about 1200 ° C., the furnace wall brick partially protruded about 35 mm. The overhanging portion had a depth of 2 m from the kiln entrance and a height direction of about 5 m from the furnace bottom. When the overhanging furnace wall bricks of the overhanging part were collected and examined, the original thickness that should have been 100 mm was only 45 mm.

In order to confirm the effect of the present invention, one combustion chamber was modeled as an analysis region. In this shape modeling, the shape was created using a predetermined preprocessor, and a calculation mesh was created. The shape is shown in FIG. The portion where the thickness was reduced on the furnace wall (see FIG. 8) was 45 mm in thickness. According to the flow of FIG. 6, physical property values, boundary conditions and the like were input, and structural analysis was performed by a finite element method. Table 1 shows the physical property values used for the incidental structure (metal) and the physical property values used in Case 1 (Comparative Example) and Case 2 (Invention Example). The boundary conditions are shown in FIG. The ceiling and bottom surfaces were constrained with zero displacement (Yy = 0) in the Y direction. The lower end of the end portion was not extended in the furnace length direction (Ux = 0). Regarding temperature, heat transfer analysis of temperature was performed in advance. Assuming an outside air temperature of 30 ° C., the heat transfer coefficient was set to 50 W / m ² K at the top and end of the furnace. The bottom of the furnace was insulated. The amount of thermal expansion was calculated from the heat transfer analysis results when the combustion chamber temperature was 800 ° C. when the furnace lid was opened and 1200 ° C. during normal operation, and was taken into account in the structural analysis as thermal stress.

In Case 1 (Comparative Example), the tensile strength and the ultimate tensile strain utilized the physical property values of the joints, and other than that, the physical property values of the bricks were utilized for structural analysis.
In case 2 (example of the present invention), the mechanical property values shown in Table 1 were obtained from a brick structure A composed of two bricks a including a joint b as shown in FIG. The brick a and the joint b of the brick structure A have the same configuration as the brick and joint of the coke oven, and the dimensions of the brick a are as follows: length L = 200 mm, width W = 100 mm, height H = 130 mm. The joint b had a thickness T = 4 mm. The joint has a dowel c, and the convex portion was R12 mm. The material of bricks and joints (mortar) was siliceous.
In both cases 1 and 2, the constitutive rules for the compression behavior and the tensile behavior are shown in FIGS.

In case 1 (comparative example), a 7 mm overhang was calculated, whereas in case 2 (invention example), a 33 mm overhang was calculated. It was found that Case 2 was able to accurately reproduce the actual deformation of the coke oven.
As described above, the structure is made by utilizing the mechanical properties of the brick structure A composed of two or more bricks a including the joints b (the bricks a and joints b have the same configuration as the bricks and joints of the brick structure). The analysis revealed that the deformation of the coke oven can be grasped with high accuracy.

A brick structure a brick b joint c dowel 1 input unit 2 arithmetic processing unit 3 output unit

Claims (2)

The brick structure is modeled, the mechanical property value of the brick structure and boundary conditions are given, the structure analysis is performed by the finite element method, and the deformation amount of the brick structure is calculated,
The brick structure is a coke oven, and the mechanical properties of the brick structure are two or more bricks (a) including joints (b). The bricks (a) and joints (b) are bricks. A method for calculating a deformation amount of a brick structure, wherein a value obtained in advance by a test using a brick structure (A) having a structure equivalent to a brick and joints of the structure is used.   When the principal stress calculated in the structural analysis exceeds the tensile strength, it is judged that cracks will occur in the direction perpendicular to the principal stress direction, and the constitutive law of tensile behavior that softens in the direction perpendicular to the crack is applied. The deformation | transformation amount calculation method of the brick structure of Claim 1 to do.

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