JP4887883B2 - Coke strength estimation method - Google Patents

Description

  The present invention relates to a method for estimating coke strength when producing coke having a predetermined strength by dry distillation of coal blended with simple coal and a plurality of brands of coal.

  In blast furnace operation, coke plays a role not only as a heat source and a reducing material, but also as a spacer for ensuring air permeability in the furnace. Therefore, the coke is required to have high strength in order to withstand the impact during transportation to the blast furnace and dropping or descending in the blast furnace.

  When producing coke for blast furnace, raw coal containing various brands of coal, such as blended coal with more than ten brands of simple coal and blended with several brands of coal, is charged into the coke oven. And dry distillation. Since the quality of the raw coal varies from brand to brand, in order to stably produce coke with the required quality, the coke strength is estimated in advance from the characteristics and operating conditions of each coal to be blended, and then blended based on it. It is necessary to set the design and operating conditions of the coke oven.

  If this coke strength can be estimated appropriately, coke having a desired strength can be stably produced. In addition, by adding a large amount of high-quality and expensive caking coal, coke quality (especially strength) is increased more than necessary to avoid excessive quality, ensuring appropriate quality according to the purpose of use. This can lead to cost reduction.

  Rotational strength is widely used as an index representing the strength of coke in a blast furnace. As the rotational strength, for example, after processing coke as a sample in a rotating drum at a predetermined number of revolutions, the mass of coke on the sieve screened with a predetermined sieve is the initial sample mass (of the coke used for the test). Rotational strength expressed as a percentage of the total mass) is common. This test method is thought to simulate the coke transport process and destruction during blast furnace charging, and because 10 kg of coke is used as the sample, the representativeness of the sample with respect to coke with non-uniform properties The reason is that it is secured.

  There are several other test methods for rotational strength, and Table 1 shows the outline.

  As shown in Table 1, JIS drum strength index, ASTM (and JIS) tumbler strength index, ISO (and DIN, NF) Mycom strength index, NF (and ISO) Ilsid strength index is used.

  The strength of coke itself includes tensile strength and compressive strength. The tensile strength is the breaking strength per unit area, and the compressive strength is, for example, the strength calculated from the diameter of the indentation that occurs when an alumina sphere of a predetermined size is pressed against the cut coke lump surface with a predetermined load. That is. These are thought to represent the strength of the coke substrate.

  In Patent Document 1, the compressive strength (indicated by the strength Hb of the coke mass in the same document) was obtained from the substrate strength of various coke tissues such as isotropic tissue and mosaic tissue and the frequency of existence of each tissue, and obtained. A method for estimating the drum strength index from a correlation equation between the compressive strength and the drum strength index (the ratio [mass%] of a coke lump having a particle diameter of 15 mm or more after 150 revolutions measured by a method defined in JIS K 2151). It is disclosed.

  However, these strengths (tensile strength and compressive strength) cannot fully reflect the effects of millimeter-order cracks existing in the coke mass, and fully express the overall fracture behavior of coke in a blast furnace. It's hard to say.

  By the way, what is characteristic of the rotational strength described above is that the amount of coke powder generated after rotation is evaluated using two types of sieve mesh, that is, it is evaluated by a binary index. For example, in the tumbler strength (TI) shown in Table 1 above,> 25 mm [%] (meaning the ratio of mass of coke on the sieve screened by 25 mm sieve [mass%]) and> 6 mm [%] (6 mm sieve) The ratio on the sieve screened with

  The reason for this is that there are at least two types of coke fracture mechanisms: volume fracture and surface fracture. In order to express the degree of two different fractures of these mechanisms, the coke strength is evaluated with a binary index. Conceivable. Note that the above-mentioned volume fracture is a fracture caused by a relatively large defect (mainly, a millimeter-order crack) in coke, and a relatively large powder is generated. On the other hand, surface fracture is a fracture at a microscopic level not affected by the crack, and it is generally considered that relatively small powder is generated.

The drum strength mainly used in Japan is usually the mass of coke on a sieve (particle size greater than 15 mm) that is sieved with a 15 mm sieve after rotating a rotating drum charged with a predetermined amount of coke for 150 revolutions. Is evaluated as a percentage (15 mm index) with respect to the total charged coke mass. The drum strength is DI ¹⁵⁰ ₁₅ . In addition, it has been pointed out that the powder under the sieve (particle size of 15 mm or less) sieved with a sieve having a mesh size of 15 mm generated when the drum rotates is mixed with those caused by volume fracture and surface fracture.

  Many methods for estimating the drum strength index from coal properties and operating conditions have been proposed so far, but many conventional methods for estimating the strength of coke are a combination of two types of coke powder generated by different fracture mechanisms. Thus, it can be said that the relationship between the properties of coal and the operating conditions is organized.

  However, essentially, the amount of coke powder produced with different fracture mechanisms should be evaluated individually, for example, coke powder generated by two different fractures (volume fracture and surface fracture) of the two types of mechanisms described above. An estimation method that takes into account the granularity configuration of the As a method for estimating the coke strength, paying attention to such a coke destruction mechanism, methods described in Patent Document 2 or Patent Document 3 can be cited.

  The method for estimating the coke strength described in Patent Document 2 is a method for estimating the amount of surface fracture coke powder and the volume fracture coke powder, and calculating the rotational strength of coke using the sum thereof. The coke particle size distribution after mechanical impact shows a peak on the coarse grain side and a peak on the fine grain side, so the peak on the coarse grain side is generated by volume fracture, and the peak on the fine grain side is the surface fracture. Since the boundary is about 6 mm, the boundary particle size between surface fracture and volume fracture is set to 6 mm. That is, powder having a particle size of 6 mm or less is caused by surface destruction, and powder having a particle size exceeding 6 mm is caused by volume destruction.

  Further, Patent Literature 3 discloses a method for estimating coke strength in which the conditions of coal charging bulk density and furnace temperature are added to the method for calculating the rotational strength of coke by the method disclosed in Patent Literature 2.

  If the surface destruction is not affected by relatively large defects (millimeter-order cracks), it is considered that even smaller defects (mainly pores) affect the destruction. The pores in the coke are formed by generating gas from coal softened and melted at around 400 to 500 ° C. in the process of coking. The average particle size of coal used for coke production is 1 to 2 mm. In general, the size of the pores formed is on the order of microns. In Patent Document 2 and Patent Document 3, the boundary particle diameter of coke powder generated by surface fracture and volume fracture is set to 6 mm, and the influence of coal properties and dry distillation conditions on these two fracture mechanisms is evaluated separately. However, considering that the pore size is in the micron order, the boundary particle size of 6 mm is considered too large.

JP 2004-251850 A JP-A-9-263964 JP 2005-194358 A

  As described above, in the conventional coke strength estimation method, the coke destruction mechanism is not taken into account, or the particle size indicating the boundary between the coke powders generated by these different mechanisms even if attention is paid to the destruction mechanism. However, the accuracy of estimation is not necessarily high.

  An object of the present invention is to solve such problems and to provide a simple and highly accurate estimation method of coke strength.

  As a result of repeated studies to solve the above-mentioned problems, the present inventors generate microstructurally disrupted powder having a particle size of 0.5 mm or less among the powder generated when coke is processed in a rotating drum. It was found that the coke strength can be accurately estimated by individually estimating the rate of occurrence of macroscopic structural fracture powder having a rate and particle size of more than 0.5 mm and not more than 15 mm. The details will be described below.

  First, the inventors investigated the generation behavior of the powder for each particle diameter with respect to the generated powder having a particle diameter of 15 mm or less by changing the drum rotation speed.

That is, 10 kg of coke produced in an actual furnace having a particle size of 25 mm or more (drum strength index DI ¹⁵⁰ ₁₅ is 84.0, average particle size is 65 mm) is put into a drum tester as a sample, and an impact at a predetermined rotational speed is applied. After the addition, the particle size distribution was measured using a sieve having a minimum sieve size of up to 0.25 mm for a powder having a particle diameter of 15 mm or less. The test according to this procedure was performed as a single test, and 10 kg of the actual furnace coke collected separately was put into a drum tester as a sample, and the particle size distribution was measured in the same manner as described above while changing the rotation speed. Thus, the test which measures a particle size distribution by changing rotation speed was performed several times.

  The reason for conducting such a test is as follows.

  The destruction of coke first occurs from a millimeter-order defect (crack) in the coke mass, and a relatively large powder is generated. It is considered that such powder does not gradually occur as the drum rotation speed increases and breakage progresses and cracks decrease. On the other hand, relatively small powders are produced from fractures that are not affected by cracks and that are affected by the strength and porosity of the coke matrix. Such powder is considered to be generated constantly regardless of the number of drum rotations.

  In other words, by finding the particle size (boundary particle size) that does not change the powder generation rate even when the drum rotation speed is increased, the generated powder due to macroscopic fracture with cracks as the starting point and the microscopic effect that cracks do not affect This is because it is considered that the particle size region of the generated powder due to destruction becomes clear.

  FIG. 2 is a diagram showing the results of the test described above, with the drum rotation speed on the horizontal axis and the newly defined powder generation speed Vx on the vertical axis. The powder generation speed Vx [% / rotation] represents the generation rate [%] of powder having a particle diameter of X mm or less per one rotation of the drum, and is defined by the following equation (1).

Vx = (Nx _(b) -Nx _(a) ) / (ba) (1)
Here, a and b represent the drum rotation speed [rotation] (b> a), and Nx _(a) and Nx _(b) represent the powder generation rate [%] of the particle size Xmm or less at the rotation speeds a and b, respectively. .

  In FIG. 2, for example, the symbol □ is a particle obtained by dividing the generation rate of the under-sieving (powder having a particle size of 15 mm or less) by the number of drum rotations according to the above equation (1) when sieving using a 15-mm sieve. The generation speed Vx of the powder having a diameter of 15 mm or less (that is, the generation rate of the powder having a particle diameter of 15 mm or less per one rotation of the drum) is represented. Further, for example, the symbol ● represents the generation rate Vx of powder having a particle size of 0.5 mm or less (the generation rate of powder having a particle size of 0.5 mm or less per drum rotation).

  As shown in FIG. 2, powder having a larger particle diameter was more frequently generated at the initial stage after the start of drum rotation, and the generation amount tended to decrease as the rotation speed increased. Furthermore, since the generation speed of the powder having a particle diameter of 0.5 mm or less indicated by the symbol ● is almost constant regardless of the drum rotation speed, the boundary particle size of the coke powder produced by macroscopic destruction and microscopic destruction is It is considered to be about 0.5 mm.

  Therefore, the coke powder having a particle size of 0.5 mm or less is referred to as “microscopic structural fracture powder”, and the coke powder of greater than 0.5 mm to 15 mm or less is referred to as “macroscopic structural fracture powder”. As a result, it was found that the coke strength (drum strength) can be accurately estimated.

  The present invention has been made on the basis of such a concept and the knowledge obtained thereby, and the gist thereof is the following coke strength estimation method.

That is, the coal properties and operating conditions or rads ram rotation microstructure breakdown powder ratio particle size which occurs following 0.5mm at study and particle size 0.5mm super 15mm following macrostructure destruction powder ratio of coke oven A method for estimating the strength of coke by calculating the drum strength (DI ¹⁵⁰ ₁₅ (%)) by subtracting the sum of the microscopic structural fracture powder rate and the macroscopic structural fracture powder rate from 100 and calculating the drum strength. The structural fracture powder ratio is obtained from the relationship with the coke compressive strength, the coke compressive strength is obtained from the substrate strength and existence frequency of various coke tissues and the coke porosity, the substrate strength of various coke tissues is measured in advance, and various coke tissues are present. The frequency is obtained from the vitrinite average reflectance and the Gieseller flow rate, the coke porosity is obtained from the volatile content of the coal and the charged bulk density, and the macroscopic structural fracture powder rate is calculated from the vitrinite average antireflection rate. A method characterized by determining from the incidence and Gisera maximum fluidity degree.

  Here, “the particle size is 0.5 mm or less” refers to the sieving when sieving using a sieve having a sieve mesh of 0.5 mm, and “the particle size is more than 0.5 mm and 15 mm or less” When the sieve is screened using a 15 mm sieve, the sieve is above the 0.5 mm sieve.

In the method of estimating the coke strength of the present invention, if obtaining the microstructure breakdown powder rate from the following formula (a), conveniently determine the microstructure breakdown powder ratio, estimating the coke strength with high precision Is possible.
^{Microstructural} fracture powder rate = 21.10 x Sc ^-0.24 (a)
Here, Sc is coke compressive strength [MPa], and is obtained by the following equation (b).
Sc = Hc × exp (−k × P) (b)
In the above formula (b), Hc: coke structure average strength, k: constant [−], P: coke porosity.

Further, in the estimation method of the coke strength of the present invention, if obtaining the macrostructure destruction powder rate from the following equation (c), also conveniently you can ask for macrostructure destruction powder ratio, desirable.
Macroscopic structure breaking powder rate = (1.41 × MF ² −7.34 × MF + 16.95)
/(−1.36×Ro ² + 3.78 × Ro−1.48)
... (c)
Here, MF: Gieseeller maximum fluidity [log ddpm], Ro: Vitrinite average reflectance [%].

  According to the coke strength estimation method of the present invention, the coke strength can be easily estimated with high accuracy. This makes it possible to produce coke having a desired quality with little quality fluctuation and stably supply it to the blast furnace. Therefore, the cost of coking coal in the coke oven operation can be greatly reduced, and it can contribute to the stable operation of the blast furnace.

  Below, the estimation method of the coke intensity | strength of this invention is demonstrated concretely.

  The feature of the present invention is that the microscopic structural fracture powder rate with a particle size of 0.5 mm or less generated during the drum rotation test and the macroscopic structural fracture powder rate with a particle size of more than 0.5 mm and 15 mm or less are individually estimated. is there.

  In this way, the microstructural breakdown powder rate and the macroscopic structural breakdown powder rate are estimated separately, respectively, as described above, there are at least two types of coke destruction mechanisms, volume destruction and surface destruction. In addition, when estimating the coke strength, it can be said that it is essentially appropriate to individually evaluate the amount of coke powder (or the powder ratio) with different destruction mechanisms.

  There is no limitation on the method for estimating the microscopic structural destruction powder rate and the macroscopic structural destruction powder rate. Any method can be used as long as it can determine the amount (rate) of coke powder having a particle diameter of 0.5 mm or less and a coke powder (rate) having a particle diameter of more than 0.5 mm and 15 mm or less, which are generated during a drum rotation test. Applicable.

If the microscopic structural fracture powder rate [%] and the macroscopic structural fracture powder rate [%] generated during the drum rotation test can be estimated, the sum of the two corresponds to the coke powder rate of 15 mm or less in particle size. The drum strength (DI ¹⁵⁰ ₁₅ ) can be easily estimated by subtracting from [%].

  An example of a specific method for estimating the microscopic structural destruction powder rate and the macroscopic structural destruction powder rate will be described below. First, how to obtain the microstructural breakdown powder rate will be described.

  FIG. 3 is a diagram showing the relationship between coke compressive strength and microstructural breakdown powder rate, which is a fact found as a result of the investigation conducted continuously by the present inventors.

The “compressive strength of coke” in FIG. 3 is the strength (Hb) of the coke mass set as an intermediate strength index in Patent Document 1 described above. In the invention described in the same document, the strength (Hb) of the coke mass is obtained from the substrate strength and existence frequency of various coke tissues and the coke porosity, and the strength (Hb) and drum strength (DI ¹⁵⁰ ₁₅ ) of this coke mass. The drum strength is estimated using this relationship. In the coke strength estimation method of the present invention, the microstructural fracture rate is obtained from the coke compression strength using the relationship shown in FIG.

  As shown in FIG. 3, as the coke compressive strength increases, the generation rate of the microscopic structure breaking powder decreases. The coke compressive strength, as described above, is a strength calculated from the diameter of the indentation produced when an alumina sphere of a predetermined size is pressed against the cut coke lump surface with a predetermined load. The effect of porosity (rate) is included in the substrate strength.

  The compression strength of coke can be determined from the substrate strength and existence frequency of various coke tissues and the coke porosity, as described in Patent Document 1 described above.

  FIG. 1 is a diagram illustrating the relationship between the presence frequency of coke texture and the vitrinite average reflectance (Ro) of coal. The figure shows the coexistence frequency of a coke organization derived from a brand of coal with a moderate Gieseller fluidity (MF).

  The vitrinite reflectance (Ro) is a percentage of the ratio of reflected light and incident light under a polarizing microscope, compared to vitrinite, which is a collective term for corrit and territite, which are fine structures in coal histology. It is a representation. It becomes an index of the carbonization degree of coal, and it can be said that the higher the value of Ro, the more carbonization has progressed. As the vitrinite average reflectance (Ro), a value measured by a method defined in JIS M 8816 is used.

  Gieseller fluidity (MF) is the process of heating and heating coal, and measuring the fluidity of coal softened and melted in the range of about 400-500 ° C using a Gieseler plastometer specified in JIS M8801. The highest fluidity. In this way, it is determined whether the coal has a moderate fluidity or a fluidity (or poor).

  In the case of a brand having a high fluidity or a brand having a low fluidity, the coal is offset from the relationship shown in FIG. Here, “deviation” means that coals with high fluidity have higher order, ie, vitrinite average reflectance, than coke produced from coals with medium fluidity with the same vitrinite average reflectance. Coke formed from coal with a lot of structure formed from brands and poorly fluid is lower than coke produced from brands with moderate fluidity with the same vitrinite average reflectivity, vitrinite average. It means that more tissues are produced from coal of low reflectivity brand.

And the degree of this “deviation” is represented by “conversion rate [−]”, “isotropic tissue-mosaic tissue conversion rate (C _ISO-MO )”, “mosaic tissue-fibrous tissue conversion rate ( C _MO-FIB ) ”. For example, in the case of a brand coal in which the mosaic structure is 0.3, that is, 30% less than the existence frequency obtained from FIG. 1 and a higher degree of fibrous structure is generated, the coal Is a mosaic structure-fibrous structure conversion rate “C _MO-FIB ” = + 0.3. On the other hand, when many lower-order structures | tissues are producing | generating, a negative sign is attached | subjected and represented to a conversion rate.

  These conversion rates are expressed by the following formulas (2) and (3) as a function of the Gieseller fluidity (MF).

C _ISO-MO = −0.77 + 0.32 × MF (when Ro <0.85) (2)
C _MO-FIB = −0.36 + 0.23 × MF (0.85 ≦ Ro <1.25) (3)
The existence frequency of the coke structure can be calculated by obtaining the existence frequency of the structure from FIG. 1 and correcting these with the expressions (2) and (3).

  Table 2 exemplifies the strength measurement results of the coke structure described above. These values can be obtained for each structure by a micro Vickers hardness meter or the like. In addition, since it is thought that the strength of these coke structures changes depending on the operating conditions such as the carbonization temperature of the coke oven, if the change in strength of the coke structure when the operating conditions are changed is measured in advance, By using the strength of the coke structure corresponding to the change, it is possible to improve the estimation accuracy of the coke compression strength.

  From the existence frequency of the coke structure calculated as described above and the strength of each coke structure illustrated in Table 2, the average strength of the coke structure, that is, the strength of the coke substrate (this is referred to here as the weighted average value). (Also referred to as “coke texture average strength”) Hc can be calculated. However, the coke texture average strength Hc is a strength that does not consider the influence of pores existing in the coke mass.

The coke porosity (P) can be determined from the following equation, for example, from the volatile content (VM) and the charge bulk density (ρ _B ) of coal.

P = 1−ρ _cact / ρ _ctru (3)
ρ _cact = ρ _B / (1−ε / 100) (4)
ε = 52.82−8.31 × (3.40−0.16 × VM
+ 3.63 × 10 ⁻³ × VM ²
-2.05 × 10 ^-5 × VM ³ )
-45.3 × (ρ _B −0.73) (5)
Where ρ _ctru is the true density of the coal. Moreover, the volatile matter amount of coal is the mass percentage of the sample weight loss when coal is heated at 900 degreeC for 7 minutes, and has a close relationship with the degree of coalification.

  And the compressive strength (Sc) of coke can be calculated | required by following (6) Formula, for example using the above-mentioned coke structure average strength (Hc) and coke porosity (P). k is a constant [−].

Sc = Hc × exp (−k × P) (6)
Thus, the coke compressive strength can be obtained from the strength and existence frequency of each coke structure and the coke porosity, and the microstructural fracture powder rate can be obtained using the relationship shown in FIG. .

  The existence frequency of each coke structure is obtained by measuring the vitrinite average reflectance, which is an index of the degree of coalification, and the Gieseller flow rate required at that time is a quantitative measure of the caking property of the softened and melted coal. This is an index (caking index). Further, as described above, the coke porosity can be determined from the volatile content of coal and the charged bulk density.

  Therefore, the microstructural fracture powder rate can be estimated using the relationship shown in FIG. 3 from the coalification degree of the raw material coal, the caking property index during softening and melting, and the charged bulk density. Actual measured values may be used for the strength of each coke structure and the amount of volatile components of coal necessary for calculating the coke compressive strength.

  In addition, the estimation method of a microscopic structure destruction powder rate is not limited to the above-mentioned method. For example, the coke compression strength may be obtained by actual measurement, as employed in the embodiments described later.

  Next, how to obtain macroscopic structural destruction powder will be described.

  FIG. 4 is a diagram showing the relationship between the vitrinite average reflectance (Ro) of raw coal and the Gieseler maximum fluidity (MF) representing the fluidity of coal and the macroscopic structural fracture powder rate.

  As shown in FIG. 4, the occurrence rate of macroscopic structural destruction powder (powder having a particle size of more than 0.5 mm and 15 mm or less) increases as the vitrinite average reflectance (Ro) decreases (that is, the degree of coalification decreases). To do. In addition, when the Gieseeller maximum fluidity (MF) decreases and is smaller than about 2 [log ddpm], the influence becomes large.

  This is because when the degree of coalification decreases (that is, the volatile content increases), the coke shrinkage during dry distillation increases, cracks in the coke mass increase, and the fluidity of coal during softening This is considered to be due to the coke structure becoming brittle and decreasing the generation of relatively large powder.

  Thus, the macroscopic structural fracture powder rate can be calculated from the vitrinite average reflectance, which is an indicator of the degree of coalification, and the Gieseler maximum fluidity, which is a caking property index.

  In addition, the estimation method of macroscopic structure destruction powder is not limited to the above-mentioned method. The relationship with other factors may be investigated and determined based on that.

  As described above, the microscopic structural destruction powder rate with a particle size of 0.5 mm or less generated during the drum rotation test and the macroscopic structural destruction powder rate with a particle size of more than 0.5 mm and 15 mm or less are individually estimated. can do.

The coke strength estimation method of the present invention is a method for estimating the microscopic structural fracture powder rate and the macroscopic structural fracture powder rate individually, and the sum of the two is a powder having a particle size of 15 mm or less generated during a drum rotation test. Rate. In the drum rotation test, since the percentage of the mass of the coke mass having a particle diameter of more than 15 mm with respect to the initial sample mass is the drum strength (DI ¹⁵⁰ ₁₅ ), the sum of the microstructural fracture powder rate and the macroscopic structural fracture powder rate is reduced from 100. Thus, the drum strength (DI ¹⁵⁰ ₁₅ ) can be calculated (estimated).

  By using the method of the present invention, it is possible to estimate the coke strength by reflecting the coke destruction mechanism, which is considered to have two types of volume destruction and surface destruction, and increase the accuracy of the estimation. it can.

  In order to confirm the effect of the present invention, the drum strength of each coke obtained by dry distillation of 9 brands of simple coal is measured, and the estimated value of the coke strength according to the method of the present invention is compared with the measured value. It was.

A test coke oven with a coal charge of about 350 kg was used for coal carbonization. The charging density was 740 kg / m ³ , the dry distillation temperature was 1100 ° C., and the coke cake was discharged from the furnace when the coke temperature in the middle of the coal reached 950 ° C. The carbonization time was about 22 hours.

  After discharging, the coke cake was cooled under a nitrogen flow, and then the particle size distribution of the coke was measured. A sample of 10 kg was proportionally sampled according to the particle size distribution of the coke having a particle size of 25 mm or more and subjected to a drum strength test.

The particle size distribution of the coke mass (and powder) after rotating the drum 150 was measured using a sieve of 75 mm to 0.5 mm, and the percentage of the mass of the coke mass having a particle diameter of more than 15 mm relative to the initial sample mass was determined as the drum strength (DI ¹⁵⁰ ₁₅ ). Similarly, the generation rate of coke powder having a particle size of more than 0.5 mm and 15 mm or less was defined as the macroscopic structural destruction powder rate, and the generation rate of coke powder having a particle size of 0.5 mm or less was defined as the microstructural breakdown powder rate.

  Moreover, about each coke obtained by dry distillation, the coke lump was cut into about 20 mm cube so that the position of 80 mm from a furnace wall might become a measurement surface, and the compressive strength (Sc) was measured. The diameter of the alumina sphere used for the measurement was 20 mm, and the pressing load was 294 N (30 kgf).

Table 3 shows the properties of coal of each brand (Vitrinite average reflectance Ro, volatile matter amount VM and Gieseler maximum fluidity MF), microstructural fracture powder rate, macroscopic structural fracture powder rate, coke compressive strength (Sc) and drum The measured value of strength (DI ¹⁵⁰ ₁₅ ) is shown.

In Table 3, the drum strength DI ¹⁵⁰ ₁₅ (estimated value according to the present invention) is determined from the relationship shown in FIG. 3 using the actual measured compressive strength (Sc), and the microstructural fracture powder rate is obtained. It can be calculated by obtaining the macroscopic structural destruction powder rate from the relationship shown in FIG. 4 using the average reflectance (Ro) and the Gieseler maximum fluidity (MF) and subtracting the sum of the two from 100.

However, here, the microscopic structural fracture powder rate is obtained from the following equation (7) that is formulated based on the measurement data of FIG. 3, and the following (8) that is formulated based on the measurement data of FIG. 4. The macroscopic structural fracture powder rate was calculated from the equation, and the drum strength DI ¹⁵⁰ ₁₅ was calculated by the following equation (9) to obtain the drum strength DI ¹⁵⁰ ₁₅ (estimated value according to the present invention).

^{Microstructural} fracture powder rate = 21.10 x Sc ^-0.24 (7)
Here, Sc: compressive strength [MPa]
Macroscopic structure breaking powder rate = (1.41 × MF ² −7.34 × MF + 16.95)
/(−1.36×Ro ² + 3.78 × Ro−1.48)
... (8)
Here, MF: Maximum Guesser fluidity [log ddpm]
Ro: Vitrinite average reflectance [%]
DI ¹⁵⁰ ₁₅ = 100− (microscopic structural destruction powder rate + macroscopic structural destruction powder rate) (9)
Further, the drum strength DI ¹⁵⁰ ₁₅ (conventional method estimated value) shown in Table 3 is obtained from the correlation equation between the compressive strength and the drum strength index disclosed in the above-mentioned Patent Document 1 (hereinafter referred to as “conventional method”). ") Is an estimated value of the drum strength calculated according to the above).

  Further, in Table 3, “actual method difference of the present invention” is a difference between an actual measured value of drum strength and an estimated value obtained by the method of the present invention, and “conventional method actual difference” is an actual value of drum strength. It is the difference in the estimated value by the conventional method.

  As is clear from the results shown in Table 3, the actual difference (difference between the actual measurement value and the estimated value) is higher when the method of the present invention is applied, regardless of the brand of coal used for dry distillation. It was smaller than the case by law.

FIG. 5 is a diagram showing the relationship between the estimated value and actual measured value of the drum strength DI ¹⁵⁰ ₁₅ according to the method of the present invention and the conventional method. Although the correlation coefficient R defined by the following equation (10) is displayed in the figure, the accuracy of estimation is higher when the method of the present invention is applied than when the method of the conventional method is used.

R = {Σ (x _i −z) ² / Σ (y _i −z) ² } ^1/2 (10)
Where x _i : Estimated value (conventional method or method of the present invention)
y _i : Actual measurement
z: Average of all measured values data From the results shown in Table 3 and FIG. 5, it can be seen that the estimation method of the present invention can estimate the coke strength DI ¹⁵⁰ _{15 more} accurately than the conventional method.

  According to the coke strength estimation method of the present invention, the coke strength can be easily estimated with high accuracy, and coke having a desired quality with little quality fluctuation can be manufactured and stably supplied to the blast furnace. Therefore, the coke strength estimation method of the present invention can be effectively used in the fields of coke manufacturing and steel manufacturing.

It is a figure which illustrates the relationship between the presence frequency of a coke structure | tissue, and the vitrinite average reflectance (Ro) of coal. It is a figure which shows the relationship between the drum rotation speed and the powder generation rate (coke powder generation speed) per drum rotation for each particle size of generated powder. It is a figure which shows the relationship between the compressive strength of coke, and the microstructural destruction powder rate. It is a figure which shows the relationship between the vitrinite average reflectance (Ro) of raw material coal, the Gieseler highest fluidity (MF), and the macroscopic structure destruction powder rate. It is a diagram showing the relationship between the drum strength (DI ^0.99 ₁₅₎ estimate in accordance with the method and the conventional method of the present invention and the measured values.

Claims (3)

Individual coal properties and particle size which occurs during operational conditions or rads ram rotation test of the coke oven is the following microstructure breakdown powder ratio and particle size 0.5 mm 0.5 mm super 15mm below the macrostructure destruction powder ratio respectively This is a method for estimating the strength of coke by calculating the drum strength (DI ¹⁵⁰ ₁₅ (%)) by subtracting the sum of the microscopic structural fracture powder rate and the macroscopic structural fracture powder rate from 100, and The powder ratio is obtained from the relationship with the coke compressive strength, the coke compressive strength is obtained from the substrate strength and existence frequency of various coke tissues, and the coke porosity, the substrate strength of various coke tissues is measured in advance, and the various coke tissue existence frequencies are Calculated from vitrinite average reflectivity and Gieseller flow rate, coke porosity from coal volatiles and charge bulk density, macroscopic structural fracture powder rate, vitrinite average reflectivity and Estimation method of the coke strength and obtaining from the error maximum fluidity degree.
The coke strength estimation method according to claim 1, wherein the microstructural fracture powder rate is obtained by the following equation (a) .
^{Microstructural} fracture powder rate = 21.10 x Sc ^-0.24 (a)
Here, Sc is coke compressive strength [MPa], and is obtained by the following equation (b).
Sc = Hc × exp (−k × P) (b)
In the above formula (b), Hc: coke structure average strength, k: constant [−], P: coke porosity.
The coke strength estimation method according to claim 1 or 2 , wherein the macroscopic structural destruction powder rate is obtained by the following equation (c) .
Macroscopic structure breaking powder rate = (1.41 × MF ² −7.34 × MF + 16.95)
/(−1.36×Ro ² + 3.78 × Ro−1.48)
... (c)
Here, MF: Gieseeller maximum fluidity [log ddpm], Ro: Vitrinite average reflectance [%].

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