JP2008095121A - Method for evaluating blended coal of raw material for manufacturing blast furnace coke - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a simple and efficient method for measuring the size of coke cake particles and the number of cracks on coke cakes in a coal dry distillation testing furnace, by measuring directly the surface profile without decomposition of coke cakes derived from the coal dry distillation testing furnace to thereby determine the number of cracks on the coal cakes and additionally to determine the coke particle diameter from the number of cracks. <P>SOLUTION: The method for evaluating a blended coal of a raw material for manufacturing the coke in the coal dry distillation testing furnace, comprises measuring the surface profile of the coke cakes obtained by charging the above blended coal of the raw material into the coal dry distillation testing furnace and by dry distillation thereof, distinguishing primary cracks and secondary cracks from the measured values on the width and depth of the cracks existing on the surface of the above coke cakes, then measuring the average surface area SA of the cokes divided by the primary cracks and of the average number NB of the secondary cracks inside cake bulks divided by the primary cracks, and finally determining the average particle diameter of the cokes or the extrusion resistance of the cakes based on the SA and the NB. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for evaluating a raw coal blend for coke production, which is important in quality control of coke for blast furnace and operation management of coke oven, and particularly obtained in a coal dry distillation test furnace. The present invention relates to a method for measuring the surface shape of the obtained coke cake to determine the crack state of the coke cake, and estimating the extrudability of the coke cake and the particle size of the coke for the blast furnace based on the crack state.

  In general, coking coal for coke production is suitable for coking coal by confirming the coke properties such as strength measurement of coke after carrying out dry distillation in the coal dry distillation test furnace before each actual furnace operation. It is customary to evaluate. As a typical dry distillation test apparatus, the height of a coal charging portion (hereinafter referred to as a carbonization chamber) of a dry distillation test furnace is 0.4 to 1.0 m, a width is 0.4 to 0.45 m, and a length is It is 0.5 to 1.0 m, and the weight of coal used per dry distillation test is about 60 to 400 kg.

  The heating method is an indirect heating method similar to that of an actual coke oven, but there are various types of heating wall materials ranging from a test furnace using the same silica brick as the actual coke oven to one using a silicon carbide plate. . In the dry distillation test, coal previously pulverized and adjusted is charged into a carbonization chamber of a dry distillation furnace, and heated from a heating wall to dry dry. After a predetermined time has elapsed, the coke is discharged from the carbonization chamber, cooled with nitrogen or water, and then subjected to a coke property measurement test. In the coke properties, what has been regarded as important is the drum strength index measured by the drum strength test method described in JIS K2151, but in recent years, when managing the operation of blast furnaces and coke ovens. The importance of confirming the coke grain size and crack condition of the coke cake has been pointed out.

  Regarding the coke particle size, when used in a blast furnace, if the particle size is small, the air permeability in the blast furnace deteriorates and the operation of the blast furnace becomes unstable, so it is important to maintain the coke particle size above the prescribed control value It becomes. As a method for measuring the coke particle size, conventionally, after disassembling a coke cake obtained by carbonization in a coal carbonization test furnace, the coke cake is dropped several times from a predetermined height, or without performing a dropping treatment, JIS K2151 After giving a predetermined impact by the drum rotating machine described in 1), a method is used in which an operator obtains an average particle size by manually sieving the obtained coke mass for each particle size. Therefore, the conventional method for measuring the coke particle size in the coal distillation test furnace has a problem that it takes manpower and time.

  In addition, the crack condition of the coke cake is considered to be related to the coke extrudability when extruding the coke cake from the carbonization chamber after coal dry distillation. In general, when coke is discharged after carbonization (extrusion), if the coke cake becomes clogged in the carbonization chamber and extrusion is difficult (stopped) or impossible (clogging), the coke oven Excessive load acts on the furnace wall, causing damage to the coke oven wall. Even in daily operations, when clogging or clogging occurs, the production of coke as a furnace group decreases due to interruptions in operation or changes in the charging schedule, and the amount of heat consumed increases due to the increase in the time required for extrusion. This will increase coke production costs. For this reason, stably extruding coke cake is an extremely important issue in preventing damage to the coke oven furnace wall and in stable operation.

  Regarding the relationship between the number of cracks in the coke cake and the coke extrusion property, when the number of cracks in the coke cake is large, the force in the furnace length direction when the coke cake is extruded from the carbonization chamber by the extruder is the furnace wall direction (in the furnace length direction). It is considered that the rate of propagation in the direction perpendicular to the force increases. However, a method for measuring the number of cracks in a coke cake that correlates with the extrudability of the coke cake has not been known.

  In view of the problems of the conventional method as described above, the present invention is to disassemble the coke cake obtained by dry distillation in the coal dry distillation test furnace to measure the coke particle size and the number of cracks of the coke cake in the coal dry distillation test furnace. The coke cake crack number is obtained by directly measuring the surface shape of the coke cake, and the coke grain size and the coke cake crack number obtaining method for obtaining the coke particle size from the crack number are provided.

The gist of the present invention is that
(1) In the evaluation method of raw coal blend for coke production by a coal dry distillation test furnace, the surface shape of the coke cake obtained by charging the raw coal blend into the coal dry distillation test furnace and dry distillation is measured. Based on the measurement values of the width and depth of cracks existing on the surface of the coke cake, those having a width of 0.5 mm or more and less than 3 mm and a depth of 5 mm or more and less than 20 mm are defined as secondary cracks, otherwise After determining the main crack and the secondary crack with the main crack as the main crack, the average area SA of the coke divided by the main crack and the average number NB of the secondary cracks in the coke mass divided by the main crack are measured, The reciprocal number of SA is defined as the average number of coke divisions NA due to main cracks per unit area, and the coke cake is removed from the carbonization chamber by the following equation (2) based on these NA and NB. Raw material compounding evaluation method of coal for coke production from coal dry distillation test furnace, characterized in that to evaluate the coke extrusion resistance when begin to.
Coke extrusion resistance = d × NA + e × NB + f (2)
here,
NA: Average number of coke divisions per unit area due to main cracks (pieces / cm ² )
NB: Average number of secondary cracks in the coke block divided by the main crack (pieces / block)
d, e, f: coefficients obtained experimentally

(2) The measurement of the surface shape of the coke cake is automatically measured by a three-dimensional shape measuring device including a laser displacement meter installed so as to be movable on an automatic biaxial stage. The evaluation method of the raw material combination coal for coke manufacture by the coal dry distillation test furnace as described in (1).

  As described above, in the method of evaluating the raw coal blend for coke production in the coal dry distillation test furnace according to the present invention, the grain size of the blast furnace coke which is important in performing quality control of the blast furnace coke and operation management of the coke oven. By measuring the surface shape directly without disassembling the coke cake obtained in the coal carbonization test furnace, it is possible to carry out the measurement and the evaluation of the coke extrudability more simply and efficiently than in the conventional method.

  Hereinafter, the present invention will be described in detail. After the coal carbonization, many cracks are observed on the surface of the coke cake facing the furnace wall. The present inventor grasps the coke cake crack condition by directly measuring the surface shape of the coke cake obtained by carbonization in a coal carbonization test furnace without disassembling, and further determines the coke particle size from the crack condition. We intensively studied the required simple and efficient methods. As a result, depending on the width and depth of the crack, there are two types: a main crack (crack that reaches the center in the width direction of the coking chamber and divides the coke mass) and a secondary crack (a crack that stops in the middle of the coke mass). It is possible to estimate the coke particle size and coke extrudability by determining the average number of coke divisions due to main cracks per unit area and the average number of secondary cracks in the coke mass divided by main cracks. I found out. The present invention has been completed based on these findings.

  The present invention will be described in detail below. As a method for measuring the surface shape of the coke cake, in particular, the depth and width of the crack, for example, as shown in FIG. 1, a surface 1 of the coke cake facing the furnace wall is replaced with a laser displacement meter 3 and an automatic biaxial stage 2. , An automatic biaxial stage controller 4 for controlling and storing the position of the displacement meter 3 on the automatic biaxial stage 2, a displacement recorder 5 for recording the measured value of the displacement meter 3, and a data processing device 6. There is a method of automatically measuring with a three-dimensional shape measuring apparatus.

  The unevenness of the coke cake surface is set so that the laser displacement meter can be moved on the automatic biaxial stage installed parallel to the surface of the coke cake, and the laser displacement meter is moved by the automatic biaxial stage controller. The three-dimensional shape of the entire coke cake surface can be measured by measuring the displacement and recording the movement amount and the displacement measurement value in the data processing device. The measured value of the laser displacement meter is also recorded by a displacement recorder.

  FIG. 2 is a schematic view of the positional relationship between the coke cake and the laser displacement meter as viewed from the cross section in the furnace width direction of the carbonization chamber (cross section perpendicular to the furnace wall). As shown in FIG. 2, the width of the crack and the depth of the crack are obtained by data processing the three-dimensional shape information (concave / convex information) of the coke cake surface 1 measured by the laser displacement meter 1, thereby obtaining the main crack 7. And secondary cracks 8 can be discriminated.

Further, as shown in FIG. 3, these measurement data are further subjected to image analysis processing, and an average value of the areas of the respective parts divided by the main crack 7 is obtained, whereby the average area SA of the coke divided by the main crack 7 is obtained. (Cm ² ) can be obtained. Further, the average number NB (pieces / lumps) of secondary cracks in the coke lump divided by the main crack can be obtained by the same method.

  In the coke cake used by the inventor, a crack having a width of 0.5 mm or more or a depth of 5 mm or more is determined as a crack, and among them, the width is 0.5 mm or more and less than 3 mm and the depth is 5 mm or more and less than 20 mm. The thing was made into the secondary crack, and the thing other than that was made into the main crack.

  As a simpler measurement method than the three-dimensional shape measurement method using the laser displacement meter, the crack width can be obtained by image processing an image obtained by photographing the surface of the coke cake with a digital camera or the like. According to the present inventor, it is possible to discriminate both to some extent by evaluating a crack having a crack width of 3 mm or more as a main crack and a crack having a width of 0.5 mm to less than 3 mm as a secondary crack. Met. However, this method is simpler than the above-described three-dimensional shape measurement method using a laser displacement meter, but only two-dimensional information on the coke surface can be obtained. The next crack cannot be discriminated, and the discrimination accuracy is lower than the three-dimensional shape measurement method using a laser displacement meter. As a specific problem, a crack having a crack width of 0.5 mm or more and less than 3 mm and a crack depth of 20 mm or more, which should originally be determined as a main crack, is determined as a secondary crack.

In the present invention, the average area SA (cm ² ) of coke divided by the main cracks and the average number of secondary cracks in the coke mass divided by the main cracks by the method for measuring the surface shape of the coke cake as described above. NB (pieces / block) can be obtained.

In the present invention, the particle size of the coke is determined by the average area SA of the coke divided by the main crack according to the following equation (1) and the average number NB of secondary cracks in the coke mass divided by the main crack (pieces / piece). Expressed as a function of lump).
Average particle size of coke = a × (SA) ^1/2 + b × (SA / NB) ^1/2 + c
(1)
here,
SA: Average area of coke divided by main cracks (cm ² )
NB: Average number of secondary cracks in the coke block divided by the main crack (pieces / block)
a, b, c: coefficients obtained experimentally

  The average coke size determined by the above formula (1) based on the main cracks and secondary cracks according to the present invention is the average coke measured by sieving the coke cake obtained in the coal dry distillation test furnace by the conventional method and directly sieving. It is in good agreement with the particle size.

In the present invention, the extrusion resistance of the coke is determined by the following formula (2): the reciprocal number NA of the average area SA of the coke divided by the main crack and the average number NB of secondary cracks in the coke mass divided by the main crack ( Expressed as a function of
Coke extrusion resistance = d × NA + e × NB + f (2)
here,
NA: Average number of coke divisions per unit area due to main cracks (pieces / cm ² )
NB: Average number of secondary cracks in the coke block divided by the main crack (pieces / block)
d, e, f: coefficients obtained experimentally

  The extrusion resistance of the coke obtained by the above equation (2) based on the main crack and the secondary crack according to the present invention is in good agreement with the actually measured value. Therefore, according to the present invention, it is possible to measure the particle size of coke for blast furnace and evaluate the coke extrusion property more simply and more quickly than the conventional method using coke obtained in a coal carbonization test furnace.

  Next, examples of dry distillation test coke evaluation according to the present invention will be shown. Here, coal having a pulverized particle size of 3 mm under 80% and moisture 5% was charged from the top of the furnace into a movable wall type dry distillation test apparatus having a height of 1100 mm, a width of 450 mm, and a length of 1050 mm. The charging density of coal was 0.75 t / m3. The properties of the coal used in the test were Ash 8.7%, VM 26.9%, and total expansion rate 60%. Here, the total expansion coefficient is a value measured in an expansion test by the dilatometer method defined in JIS M8801.

  The dry distillation test was performed under several conditions in which the furnace temperature was changed from 1100 ° C. to 1300 ° C. and the setting time was changed in the range of 0 hour to 6 hours. After the end of dry distillation, the extrusion resistance when extruding the coke cake was measured. Here, the extrusion resistance refers to the pressure applied perpendicular to the furnace wall when pushing the coke cake with the extrusion ram with the coke side furnace lid closed, and the pressure applied to the extrusion ram (parallel to the furnace wall with respect to the coke cake) The pressure acting on the ratio was evaluated. The larger this ratio, the greater the extrusion resistance because the force of the extrusion ram escapes to the wall side without being transmitted to the coke cake.

In addition, the coke cake is cooled with nitrogen gas in the cooling chamber after being discharged from the furnace, and before breaking the coke cake after cooling, an apparatus comprising a laser displacement meter and an automatic biaxial stage as described above is used. The coke surface shape was automatically measured, and the average area SA (cm ² ) of the coke divided by the main crack and the average number NB (pieces / block) of secondary cracks in the coke mass divided by the main crack were obtained. . Thereafter, the coke cake was disassembled and the coke average particle size was measured manually.

  FIG. 4 shows the relationship between the coke average particle size obtained by the present invention and the coke average particle size obtained manually. It can be seen that both agree well. FIG. 5 shows the relationship between the coke extrusion resistance obtained by the present invention and the measured extrusion resistance. The extrusion resistance was expressed as a relative value when the extrusion resistance was set to 1 under a dry distillation condition of a furnace temperature of 1200 ° C. and a setting time of 3 hours. It can be seen that both agree well.

It is a figure which shows an example of embodiment of this invention, and is a figure which shows the apparatus structure for measuring the surface (surface parallel to a furnace wall) of coke cake. It is the schematic diagram which looked at FIG. 1 from the cross section of a furnace width direction (cross section perpendicular | vertical with respect to a furnace wall), and is a figure which shows typically the cross section of a coke cake perpendicular | vertical to a furnace wall. It is a figure which shows the main crack on the coke cake surface measured by this invention. It is a figure which shows the relationship between the coke average particle diameter calculated | required by the method of this invention, and the coke average particle diameter calculated | required by manual labor. It is a figure which shows the relationship between the coke extrusion resistance calculated | required by the method of this invention, and the measured extrusion resistance.

Explanation of symbols

1 Coke cake surface 2 Automatic biaxial stage 3 Laser displacement meter 4 Automatic biaxial stage controller 5 Displacement recorder 6 Data processing device 7 Main crack 8 Secondary crack

Claims (2)

In the method for evaluating raw coal blend for coke production by a coal dry distillation test furnace, the surface shape of the coke cake obtained by charging the raw coal blend into the coal dry distillation test furnace and dry distillation is measured, and the coke Based on the measurement values of the width and depth of cracks existing on the cake surface, those having a width of 0.5 mm or more and less than 3 mm and a depth of 5 mm or more and less than 20 mm are defined as secondary cracks, and other cracks are determined. After discriminating the main crack and the secondary crack as the main crack, the average area SA of the coke divided by the main crack and the average number NB of the secondary cracks in the coke mass divided by the main crack are measured, and the reciprocal of SA Is defined as an average number of coke divisions NA due to main cracks per unit area, and the coke cake is extruded from the carbonization chamber according to the following equation (2) based on these NA and NB. Raw material compounding evaluation method of coal for coke production from coal dry distillation test furnace, characterized in that to evaluate the coke extrusion resistance when.
Coke extrusion resistance = d × NA + e × NB + f (2)
here,
NA: Average number of coke divisions per unit area due to main cracks (pieces / cm ² )
NB: Average number of secondary cracks in the coke block divided by the main crack (pieces / block)
d, e, f: coefficients obtained experimentally   2. The surface shape of the coke cake is automatically measured by a three-dimensional shape measuring device comprising a laser displacement meter installed so as to be movable on an automatic biaxial stage. The evaluation method of the raw material combination coal for coke manufacture by the coal carbonization test furnace of description.

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