JP2000319663A - Method of pulverizing coal for production of coke - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of pulverizing coal for the production of coke which can pulverize coal with precision without varying the formulation of raw materials and the target particle size. SOLUTION: In a repulsion type pulverizer 10 having a rotor 12 and repulsive plates 14 and 15, the relationship (V and P) between the set amounts V of the gaps 14a and 15a between the rotor 12 and the repulsive plates 14 and 15 and the variance P of the particle size of the coal after pulverization is previously found, and by regarding the difference between the measured particle size of the coal pulverized by the repulsive pulverized 10 and the target particle size after the previously set pulverization as variance P, the set amounts V are found from the relationship (V and P), and the gaps 14a and 15a between the rotor 12 and the repulsive plates 14 and 15 of the repulsion type pulverizer 10 are adjusted based on the set amounts V to effect pulverization of coal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for pulverizing coal charged into a coke oven.

[0002]

2. Description of the Related Art When a coal crusher is used in common for a plurality of storage facilities having different target particle sizes of coal, it is necessary to adjust the particle size of the coal by the coal crusher and manage the coal for each destination. At this time, the gap between the rotary rotor and the repulsion plate changes due to the wear of the blade provided on the rotary rotor, and therefore, the accuracy is reduced in the particle size management based only on the gap value (gap between the rotary rotor and the repulsion plate). . For this reason,
The following methods have been devised as methods for adjusting the particle size. Japanese Patent Publication No. 62-55899 discloses a method for controlling the particle size of raw coal, which is performed by adjusting the gap between the rotary rotor and the repulsion plate when operating while keeping the supply amount and properties of the raw material constant. In this method, the load current value supplied to the rotor is matched with the rated current value to obtain a predetermined target granularity. Further, as disclosed in JP-A-56-32587, a method of classifying with a sieve having a specific sieve, and further pulverizing each coarse particle portion on the sieve to a specific particle size or less to adjust the particle size. there were.

[0003]

However, the conventional method for pulverizing coal for producing coke has the following problems. The method disclosed in Japanese Patent Publication No. 62-55899 cannot cope with changes in the amount of coal supplied and the blending of raw materials due to feedback control from the actual current value. In addition, it is not possible to respond to a change in the target granularity in the same manner.
Automation was difficult. On the other hand, JP-A-56-32587
The method disclosed in Japanese Patent Application Laid-Open Publication No. H11-150572 requires a sieve device to be installed in addition to the coal pulverizing device, and is expensive. The present invention has been made in view of such circumstances, and an object of the present invention is to provide a method of pulverizing coal for producing coke, which can pulverize coal with high accuracy regardless of the blending of raw materials and a change in target particle size.

[0004]

According to the present invention, there is provided a method for pulverizing coal for producing coke according to the present invention, comprising the steps of: adjusting a gap between the rotor and the repulsion plate in a repulsion pulverizer having a rotor and a repulsion plate; The relationship (V, P) between the amount V and the variation P of the coal particle size after pulverization is determined in advance, and the difference between the measured particle size of the coal pulverized by the repulsion type pulverizer and the preset target particle size after pulverization is calculated. As the variation P, the relationship (V, P)
And the gap between the rotor of the repulsion pulverizer and the repulsion plate is adjusted based on the adjustment amount V to pulverize the coal. When automatically pulverizing coal, an operator first inputs a target particle size after pulverization. Thus, every time the target particle size is input or the measured particle size is determined, the control computer obtains the change amount P, calculates the gap adjustment amount V, and moves the repulsion plate of the repulsion-type crusher to the gap adjustment amount by an actuator such as a hydraulic cylinder. Move by the value of V. During the operation of the repulsion pulverizer, fine adjustment can be performed by measuring the particle size of the coal pulverized by the repulsion pulverizer at regular intervals and inputting the target particle size again. In this way, the gap between the rotor and the repulsion plate can be adjusted.
Since the relationship (V, P) between the adjustment amount V and the change amount P is input in advance, the accuracy of the coal particle size can be improved even immediately after the target particle size is changed.

Here, the relationship may be a table, but is preferably represented by the following equation. V = P (A × P ⁴ −B × P ² −C) (1) where P = (Pm−Ps) V: Adjustment amount of the gap between the rotor and the repulsion plate of the repulsion pulverizer [Mm] P: Variation of coal particle size [-3mm%] Pm: Target particle size [-3mm%] Ps: Measured particle size [-3mm%] A, B, C: Constant 3mm%: Coal with particle size of 3mm or less The coal particle size is not more than a predetermined size after grinding (for example, 3 m
(size passing through an m square sieve mesh)
Further, the amount of change in the particle size is determined by a preset target particle size after pulverization (in FIG. 2, depending on whether coal is supplied to any one of the first line 26, the second line 27, the third line 30, and the fourth line 31). Determined) and the ratio of the size of coal after pulverization (measured particle size). For example, if the particle size is 7
To increase from 0% to 80%, Pm = 8
By substituting 0 and Ps = 70, the adjustment amount V of the gap required for changing the particle size can be obtained.
Since the constants A, B, and C change depending on the size and shape of the repulsion-type pulverizer, they are obtained in advance from actual values. By using this equation, the adjustment amount V of the gap and the change amount P of the particle size are approximated by a quintic equation, so that the particle size of the coal can be accurately controlled even immediately after the target particle size is changed. . Also, the maximum fluidity MF of the coal before pulverization is 1.
When the value exceeds 5 (ddpm), the adjustment amount V of the gap can be set to the maximum value without applying the relational expression.
Here, the maximum fluidity is a value determined by the Giesera plastometer method specified in JIS, and the unit is lo.
g ₁₀ ddpm (dial division perm
inute). When this value exceeds 1.5, the average particle size of the coal is uniform and small, so
If it is further pulverized, it may be excessively pulverized and dust may be generated. In order to prevent this, the adjustment amount V of the gap of the repulsion pulverizer is set to the maximum value, and only those having an extremely large particle size can be pulverized, and the measured particle size can be hardly changed. Note that the maximum value differs depending on the type of repulsion type crusher, but refers to the distance when the distance between the rotor and the repulsion plate is separated to such an extent that dust is not generated due to excessive pulverization.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, embodiments of the present invention will be described with reference to the accompanying drawings to provide an understanding of the present invention. As shown in FIG. 1, a repulsion pulverizer 10 used in a method of pulverizing coal for coke production according to an embodiment of the present invention has a width of about 4.5 m, a depth of about 3 m,
A rotor 12 having a diameter of about 2.3 m is provided in a casing 11 having a height of about 4 m. The rotor 12 is provided with 16 impact blades 13 on the circumference, and rebound plates 14, 15 are provided above and beside the rotor 12 in the circumferential direction with adjustable gaps 14a, 15a with the impact blade 13. Have been. The details will be described below. The rotating shaft 16 of the rotor 12 is connected to a driving device via a bearing (not shown). In addition, repulsion board 1
The left ends of 4 and 15 are supported by pivot shafts 17 and 18, respectively, while the right ends of
1 are suspended by hydraulic cylinders 19 and 20 which are examples of the actuator provided in the actuator 1. Repulsion plate 14,
When the hydraulic cylinders 19 and 20 are operated, the rotary shaft 15 rotates around the rotary shafts 17 and 18 to adjust the gaps 14 a and 15 a with the impact blade 13. When the repulsion pulverizer 10 is used, coal is charged from a coal supply port 21 formed at the upper left of the casing 11. Since the rotor 12 rotates clockwise at a high speed, the charged coal is scooped up by the impact blade 13 and collides with the repulsion plates 14 and 15 and is pulverized by the impact. When adjusting the particle size, the hydraulic cylinders 19 and 20 are operated to adjust the gaps 14a and 15a between the impact blade 13 and the repulsion plates 14 and 15, thereby obtaining coal adjusted to a target particle size. Can be.

Next, the coal preparation transportation system 22 will be described with reference to FIG. The coal preparation transport system 22 includes a coal blending tank 23 in which coal before pulverization is stored by brand, and a coal blending tank 2.
A repulsion pulverizer 10 for pulverizing the coal carried from 3, a first line 26 for charging the pulverized coal into a coal dryer 24 and storing it in a first coal tower 25, A second method for storing pulverized coal directly in the first coal tower 25
A line 27, a coal pulverized by the repulsion pulverizer 10 is supplied to a coal dryer 28, a third line 30 to be supplied to a second coal tower 29, and the coal pulverized by the repulsion pulverizer 10. And a fourth line 31 that is directly stored in the second coal tower 29. Each line is constituted by a belt conveyor, and each line can be switched according to a manufacturing situation and a destination. Then, the control computer changes the blending of the coal cut out from the coal blending tank 23 depending on the production situation and the destination, adjusts the particle size of the coal pulverized by the repulsion pulverizer 10, and instructs the switching of each line.

Next, a method of pulverizing coal for producing coke will be described. The average particle size of the coal before pulverization is about 10 mm, including about 50 mm. On the other hand, those having a large caking property (maximum fluidity MF) and good fluidity have a uniform particle size, an average of about 5 to 6 mm, and are almost uniform. The coal blending tank 23 is divided into three groups, and the coal before pulverization is divided into any one of the groups according to the caking property measured in advance. Any one of the three groups has an MF of 1.5
The above groups are included, and information on the MF value of each group is input to the control computer in advance. Furthermore, each group is provided with six coal blending tanks 23,
The coal before pulverization is stored in each coal blending tank 23 by brand. The coal cut out and blended by a predetermined amount from the coal blending tank 23 of each group and transported to the repulsion pulverizer 10 is pulverized to a predetermined particle size. For example, in coal stored in the coal blending tank 23 before pulverization (about 10 mm in average particle diameter), the ratio of coal having a particle diameter of 3 mm or less is described as about 70% (hereinafter, -3 mm, 70%). ), Which contains coal having a large particle size of 10 mm or more.
By pulverizing to about 76% and making the particle size uniform, high quality coke can be produced. In some cases, about -3 mm or 70% of coal is pulverized to about -3 mm or about 80%. When the target particle size is changed in this way, the rotor 12 and the repulsion plates 14 and 15 of the repulsion pulverizer 10 are used. It is necessary to adjust the gaps 14a and 15a.

FIG. 3 shows a value obtained by subtracting the measured particle size from the target particle size in the repulsion pulverizer 10 (the change amount P of the particle size) and the gap adjustment amount (the rotor 12 and the repulsion plates 14 and 15 of the repulsion pulverizer 10). 6 is a graph showing the relationship (V, P) with the adjustment amount V) of the gaps 14a and 15a. From the relationship of this graph, the inventor of the present application has found that the adjustment amount V of the gaps 14a and 15a between the rotor 12 and the repulsion plate of the repulsion pulverizer 10 can be approximated by a fifth-order equation of the change amount P of coal particle size, The following equation was derived. V = P (A × P ⁴ −B × P ² −C) (1) where P = (Pm−Ps) V: Adjustment amount of the gap between the rotor and the repulsion plate of the repulsion pulverizer [Mm] P: variation in the particle size of coal [-3 mm%] Pm: target particle size [-3 mm%] Ps: measured particle size [-3 mm%] A, B, C: constant 3 mm%: particle size of 3 mm or less Different values are substituted into the proportions A, B, and C of the coal depending on the shape and the number of revolutions of the repulsion pulverizer 10. In addition, the same formula can be used not only at the beginning of the pulverization but also until the end of the pulverization. During the pulverization, the difference P between the target particle size and the measured particle size is input again to change the gap adjustment amount V again. Therefore, the control of the particle size can be easily performed. Among coals before pulverization, those having a maximum fluidity MF of more than 1.5 have a uniform particle size and have little merit of pulverization.
Do not apply. When the MF exceeds 1.5, the control computer of each repulsion crusher 10
The operation is performed after the adjustment amount V of 4a and 15a is maximized, that is, the gap is fully opened. By doing so, it is possible to pulverize only the coal having an extremely large particle diameter in the input coal, thereby reducing the generation of fine powder due to over-pulverization.

In advance, the rotor 12 and the repulsion plate 1
Equation 1, which is a relational expression between the adjustment amount V of the gaps 14a and 15a between 4 and 15 and the change amount P of the coal particle size after pulverization, is expressed by constants A, B,
C, and the program including the equation 1 is mounted on a control computer, and a preset target particle size Pm after the pulverization is input.
The difference between the measured particle size Ps of the coal pulverized by the repulsion pulverizer 10 is calculated as a variation P, and the adjustment amount V of the gaps 14a and 15a of the repulsion pulverizer 10 is calculated from the relational expression between the variation P and the adjustment amount V. And operating the hydraulic cylinders 19 and 20 attached to the repulsion pulverizer 10 and capable of moving the repulsion plates 14 and 15 based on the adjustment amount V, to thereby produce a gap 14 a between the rotor 12 and the repulsion plates 14 and 15. , 15a. By doing so, the coal can be pulverized at a predetermined particle size. Also, during the operation of the repulsion pulverizer 10, the coal after the pulverization is sampled every 30 minutes, the sample for eight times is reduced and analyzed, and the ratio of the coal having a particle size of 3 mm or less is measured. I have. Then, the measured values are input to a control computer, and fine adjustment is performed three times a day. In addition,
Sampling is performed from a mixture of pulverized coals conveyed from a plurality of repulsion pulverizers 10, but may be performed for each repulsion pulverizer 10. Further, these data are accumulated in the computer, and if necessary, the expression 1 can be corrected and used at the next switching. When the repulsion pulverizer 10 is operated continuously, it is difficult to perform the accurate control by manually adjusting the adjustment amount V of the gaps 14a and 15a due to a short step change time. By using a control computer for automation, it is possible to control accurately, quickly and accurately.

As shown in FIG. 2, coal after pulverization is, for example, coal pulverized to a particle size of about 76%
6 is conveyed by a belt conveyor or the like, and charged into a coal dryer 24. When the moisture of the supplied coal is about 9%, the coal is stored in the first coal tower 25 after the moisture is reduced to about 4% by the coal dryer 24. Further, the coal pulverized to a particle size of about 80% is transported through the third line 30 after switching the line, and is charged into the coal dryer 28 to reduce the water content of the coal to about 2%, and Stored in coal tower 29. In addition, the coal dryer 2
4 and 28, the drying process in the coal dryers 24 and 28 is omitted, the second line 27 or the fourth line 31 is transported, and the first coal tower 25 or the second coal tower is directly transferred. 29 can also be stored. By configuring the coal preparation transportation system 22 as described above, even if the target value changes due to line switching, the particle size adjustment in the repulsion crusher 10 can be automatically performed in conjunction with this change.
Having thus described the embodiments of the present invention, the present invention is not limited to the above embodiment, for example, term of Equation 1 P ^4, but do not include terms of P ² The present invention is also applicable to a case where a fine adjustment is made by including a term obtained by multiplying these by a constant term in Equation 1. In addition, the difference between the target granularity and the measured granularity is input as the change amount P. If the target granularity has already been input, only the measured granularity is input and the control computer calculates the change amount P. Of course.

[0012]

In the method for pulverizing coal for coke production according to claims 1 to 3, since the relationship is input in advance to the program of the control computer, even after the mixing of the raw materials and the change of the target particle size, Coal can be pulverized with high accuracy, thereby improving the quality of coke and reducing the burden on the operator. In particular,
In the method of pulverizing coal for producing coke according to the second aspect, the relational expression is approximated by a fifth-order expression, so that the particle size of the coal can be accurately controlled. In the method of pulverizing coal for coke production according to the third aspect, when the maximum fluidity MF of the coal before pulverization exceeds 1.5 (ddpm), the gap adjustment amount V is set to the maximum value. Can suppress the generation of fine powder.

[Brief description of the drawings]

FIG. 1 is a front view of a repulsion pulverizer used in a method of pulverizing coal for coke production according to one embodiment of the present invention.

FIG. 2 is an explanatory diagram of a coal preparation transportation system used in the grinding method.

FIG. 3 shows the amount of change P in the particle size of coal used in the grinding method.
6 is a graph showing the relationship between the distance and the adjustment amount V of the gap.

[Explanation of symbols]

10: repulsion type crusher, 11: casing, 12: rotor, 13: impact blade, 14, 15: repulsion plate, 14a, 15
a: gap, 16: rotation axis, 17, 18: rotation axis, 19,
20: hydraulic cylinder (actuator), 21: coal feed port, 22: coal preparation transportation system, 23: coal blending tank, 24: coal dryer, 25: first coal tower, 26: first line, 2
7: second line, 28: coal dryer, 29: second coal tower, 30: third line, 31: fourth line

Continuation of the front page F term (reference) 4D065 CA16 CB01 CC01 DD05 DD22 EB01 ED20 EE02 EE08 EE19 4H012 LA00 4H015 AA10 AB01 BA01 BB10 CA03 CB01

Claims (3)

[Claims] 1. In a repulsion pulverizer having a rotor and a repulsion plate, a relationship (V, P) between an adjustment amount V of a gap between the rotor and the repulsion plate and a change amount P of coal particle size after pulverization in advance.
Is determined, and the adjustment amount V is determined from the relationship (V, P), with the difference between the measured particle size of the coal pulverized by the repulsion type pulverizer and the preset target particle size after the pulverization as the change amount P, A method of pulverizing coal for coke production, comprising adjusting a gap between a rotor and a repulsion plate of the repulsion-type pulverizer based on the adjustment amount V to pulverize the coal. 2. A method for pulverizing coal for coke production according to claim 1, wherein said relation is expressed by the following equation. V = P (A × P ⁴ −B × P ² −C) (1) where P = (Pm−Ps) V: Adjustment amount of the gap between the rotor and the repulsion plate of the repulsion pulverizer [Mm] P: Variation of coal particle size [-3mm%] Pm: Target particle size [-3mm%] Ps: Measured particle size [-3mm%] A, B, C: Constant 3mm%: Coal with particle size of 3mm or less Percentage 3. The method for pulverizing coal for coke production according to claim 1 or 2, wherein the maximum fluidity MF of the coal before pulverization is obtained.
Is greater than 1.5, the gap adjustment amount V is set to a maximum value.