JP2000303070A - Method for operating coke oven - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for operating a coke oven by which the pushing of coke cake can be improved without causing a marked increase in cost. SOLUTION: Provided is a method for operating a coke oven comprising carbonizing a coal blend prepared by blending coking coals of a plurality of grades and discharging the carbonized coke cake from a carbonization chamber by means of a pusher, wherein the coal blend is fed into the carbonization chamber where the load on the pusher is higher than a predetermined standard value during the pushing of the coke cake after the coal blend has been prepared according to a suitably selected grades and an adjusted blending ratio in order to lower the expansion pressure of the formed coal blend so as to lower the pushing load to the standard value or below.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for operating a coke oven.

[0002]

2. Description of the Related Art In recent years, most of coke ovens in Japan are approaching the end of their service life, and their aging is progressing. Also,
An increase in the bulk density of coal charged in the coking chamber due to the introduction of a coal pretreatment technique such as a humidifying coal method, which has been actively performed in recent years, has particularly caused damage to the coking oven coking chamber. There are various types of damage to the coking chamber. Among them, damage to the side wall of the coking chamber (hereinafter referred to as furnace wall) is the most serious problem because it is impossible to completely repair it. One of the major causes of the damage to the furnace wall is that when extruding the carbonized coal (coke cake) with an extruder, it is difficult or impossible to extrude the coke cake, which places a great burden on the furnace wall. It is believed that there is.

Therefore, as a conventional method of operating a coke oven in consideration of the extrudability of coke cake from the carbonization chamber, there is a method disclosed in Japanese Patent Application Laid-Open No. 9-143473. In this method, a ratio of a side wall load to a constant pressure during coke cake compression is determined as an oven wall load index by experimental or calculation from the coking coal characteristics and operating conditions, and the coke is operated using the oven wall load index as an index. The extrudability of the cake is secured. The furnace wall load index is obtained by a calculation formula using the coking property of the coking coal characteristics and the degree of coalification, and the coking coal is selected or blended so that the obtained index value satisfies a predetermined range. The ratio is being adjusted.
Here, the coefficients in the equation for calculating the furnace wall load index are calculated from the operating conditions of the coke oven. In this method, when operating a coke oven, the ratio of the oven wall load to constant pressing during coke cake compression is used as the oven wall load index, and the operation is performed using the oven wall load index as an index. Poor extrusion of the coke cake such as stoppage or blockage of the coke cake, and damage to the coke oven (carbonization chamber) due to poor extrusion can be suppressed beforehand, which can greatly contribute to extending the life of the coke oven.

[0004]

However, the above-mentioned conventional method has the following problems to be solved. (1) Coking coal characteristics and operating conditions are indicated as furnace wall load indices to perform operations to suppress stalls. However, to clear the furnace wall load index, all coking coal used in coke ovens is It is necessary to restrict the formulation. In other words, the coking coal is generally designed in the order of the coke strength and quality (ash content, sulfur content) required by the blast furnace. However, when the furnace wall load index is reflected in the design, the degree of freedom of the coking coal mixing is reduced. It decreases significantly. As a result, it is no longer possible to respond flexibly to the supply and demand of coal (delays in the supply of coal, sluggish shipments at Yamamoto), and it becomes necessary to store more brands of coal than necessary in the raw material yard. If there is no yard, the ship that supplies coal will have to be berthed, causing significant berthing charges. (2) As a result of too many constraints, there is a possibility that the coke strength and quality required by the blast furnace may not be achieved. (3) The operating conditions for clearing the furnace wall load index are:
Need to lower the bulk density of the carbonization chamber, secure the flue temperature, etc.
These are alleviation of operating conditions that cause productivity deterioration, increase of input heat, and the like, and are not advisable in view of the direction of cost increase.

As described above, the technique of restricting the coking coal blending and operating conditions in order to clear the furnace wall load index in the conventional method has been required to significantly increase the production cost. It is intended to avoid extruding and clogging of the coke oven by increasing the cost. The present invention has been made in view of such circumstances, and it is an object of the present invention to provide a method of operating a coke oven which can improve the extrudability of a coke cake by avoiding a significant increase in cost in the operation of a coke oven. I do.

[0006]

The method of operating a coke oven according to the present invention, which meets the above object, comprises the steps of: charging a coal blend containing a plurality of brands of coal into a carbonization chamber of a coke oven;
In the operating method of a coke oven for discharging the carbonized coke cake from the carbonization chamber by an extruder, the blended coal is supplied to a carbonization chamber in which the load of the extruder at the time of extruding the coke cake is higher than a preset reference value. By adjusting the brand and blending ratio of the constituent coal, the expansion pressure of the blended coal is reduced, and the coal is charged so that the extrusion load is equal to or less than the reference value. Further, in the method of operating a coke oven according to the present invention, the blending ratio of the coal blend can be reduced in the order of brands having a higher expansion pressure.

In general, it is considered that the coal is burned down by carbonization, and when extruded from the carbonization chamber by an extruder, the contact with the furnace wall is small so that the extrusion load is not so large. However, in an actual operation, a stoppage and a blockage occur. As a result of detailed examination of the mechanism of this generation, it was found that the main factor was largely affected by the expansion pressure of coal generated during carbonization in the coke oven carbonization chamber. When carbonizing using a coal blend having a high expansion pressure (when operating in a normal coking chamber), the coal expands and then the coke shrinks (burns out). Since the width (ratio) of burnout is substantially constant regardless of the expansion pressure, the pressure applied to the furnace wall of the coke cake after carbonization increases by the amount of expansion (or the gap with the furnace wall decreases). ). Therefore, in this case, it is considered that the contact between the furnace wall and the coke increases during extrusion, and the extrusion load increases.

[0008] To confirm this, blended brands of blended coal
The relationship with the load at the time of extruding the coke cake was investigated by adjusting the mixing ratio and changing the expansion pressure. The result is shown in FIG. As shown in FIG. 1, it can be seen that the relative extrusion load increases as the expansion pressure increases. This shows that the expansion pressure greatly affects the extrudability of the coke cake. In addition, comparing the normal kiln (a sound carbonization chamber with no damage to the furnace wall) and the control kiln (a carbonization chamber with a damaged furnace wall), as shown in FIG. It was found that the load was large and the rate of change was large. Based on these findings, considering the carbonization chamber in which the furnace wall is damaged (brick loss, etc.), in this case, the coke in contact with the damaged part of the furnace wall becomes a healthy furnace wall. It is presumed that the coke protrudes from the contacting coke, and this portion is considered to be a major obstacle, causing a significant increase in the extrusion load. Therefore, it can be said that the increase in the contact between the furnace wall and the coke is fatal, especially for the carbonization chamber in which the furnace wall is damaged.

Therefore, in the present invention, the brand and the proportion of the coal constituting the blended coal are adjusted to a carbonization chamber in which the load of the extruder at the time of extruding the coke cake is higher than a predetermined reference value than in a normal carbonization chamber. By charging and reducing the inflation pressure of the coal blend, the extrusion load is reduced to the reference value or less,
Suppresses and prevents clogging of the coke oven. Further, by decreasing the blending ratio in the order of brands having the highest expansion pressure of the blended coal, the expansion pressure of the blended coal is reduced, the extrusion load is reduced to the reference value or less, and the coke oven is stopped and clogged. Suppress. In addition, the carbonization chamber in which the load at the time of extruding the coke cake is higher than the reference value set in advance than the normal carbonization chamber includes not only the chamber in which the load is actually high but also the chamber in which the load may be high.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, embodiments of the present invention will be described to provide an understanding of the present invention.

A method of operating a coke oven according to one embodiment of the present invention is to carbonize blended coal obtained by blending a plurality of brands of coking coal, and then discharge the carbonized coke cake from a carbonization chamber using an extruder. It is characterized in that a blended coal different from the blended coal to be put into the normal coking chamber is placed in the coking chamber where the load at the time of extruding the coke cake is higher than that in the usual coking chamber. The details will be described below. In the method of operating a coke oven according to the present embodiment, first, in the coke oven, a carbonization chamber in which the load of the extruder at the time of extruding the coke cake is higher than in a normal carbonization chamber is specified. As this method, the load of the motor at the time of extrusion in the previous operation is detected, the detected value is compared with a preset reference value, and it can be specified under the condition that the detection value> the reference value.

When a carbonization chamber having a higher load than that of the normal carbonization chamber is specified in this way, a coal blend B different from a coal blend A containing a plurality of brands of raw coals to be put into other normal carbonization chambers is formed. That is, (1) change of blending brand of coal, (2) change of blending ratio of each brand coal, and (3) one or two or more in order of increasing inflation pressure so that the extrusion load in the extruder becomes lower than the reference value. A blended coal B having a low expansion pressure is formed by cutting a brand, for example, Russian coal or Australian coal. It is preferable to select the above (1) to (3) according to the supply and demand of coal, and it is possible to set the direction to improve the quality as much as possible (in the direction of high expansion pressure) according to the state of the load of extrusion. It is. Then, the blended coal A is put into the normal carbonization chamber as usual, and the blended coal B is put into the carbonization chamber with a higher load than the normal carbonization chamber. Is extruded by an extruder and discharged from the carbonization chamber.

As described above, in the carbonization chamber where the load is higher than that of the normal carbonization chamber, the coke cake after the carbonization has a larger gap than the furnace wall in order to carbonize the coal B having a low expansion pressure. Therefore, the coke cake can be discharged from the carbonization chamber with a low load while ensuring the extrudability without being pressed and clogging at the time of extrusion. Therefore, it is possible to suppress further damage to the damaged carbonization chamber. In addition, it stops,
Since the pushing force concentrates on the furnace wall and curves in the carbonized chamber that has been clogged, this also causes the bending of the carbonized chambers on both sides, thereby stopping the carbonized chambers on both sides and inducing the blockage.
Therefore, by suppressing and preventing the carbonization chamber in which the furnace wall is damaged from being pressed and clogged, the entire coke oven can be suppressed from being pressed and clogged. Furthermore, when viewed as a whole coke oven, the number of coke ovens having a higher load than that of a normal coke oven is small, and the coke quality required by the blast furnace can be sufficiently ensured.

[0014]

EXAMPLES Examples of the method for operating a coke oven according to the present invention will be described with reference to Tables 1 and 2 together with Comparative Examples. In this example and the comparative example, each brand coal A to L
And the expansion pressure of each brand coal is as described in JP-A-4-27.
It is calculated by the method proposed in Japanese Patent No. 2992. Also, the blending coal expansion pressure of each of these brand coals is disclosed in JP-A-6-2121.
Calculated by the method proposed in JP-A-64-64.

[0015]

[Table 1]

[0016]

[Table 2]

[0017] Table 1 the maximum inflation pressure P _i of each stock coal A~L
Table 2 shows the expansion pressures (estimated expansion pressures) P _X of the coal blends of Examples 1 and 2 and Comparative Examples 1 and 2. The arithmetic mean inflation pressure P ₀ of the blended coal is the maximum inflation pressure P _i of each brand coal A to L.
And based on the proportion Y _i of that brand coal was calculated by the following equation (1). P ₀ = ΣP _i × Y _i / 100 (1) Since coal has a temperature range where the maximum expansion force varies depending on the brand, the expansion pressure acting on the inner wall of the carbonization chamber was calculated by the above equation (1). Different from the arithmetic mean inflation pressure P ₀ . For this reason, the inflation pressure P _{X of the} coal blend shown in Table 2 acting on the inner wall of the coking chamber was calculated from the above-mentioned arithmetic mean inflation pressure P ₀ using the following equation (2). P _X = a × P ₀ + b (2) where a and b are coefficients. Further, 27 tons of blended coal blended in this way were charged into the carbonization chamber of a coke oven,
After dry distillation at a furnace temperature of 1120 ° C. for 18 hours, the mixture was extruded with an extrusion ram of an extruder, and the result of measuring the extrusion load peak current of the extrusion ram of the extruder at that time is shown in Table 2. In addition, the reference value of the extrusion load peak current of the extrusion ram of this extruder is 250 (A), which is a load current when a stable operation is performed without adversely affecting the furnace wall of the coking chamber.

(Comparative Example 1) Comparative Example 1 was intended for a carbonization chamber in which the furnace wall was not damaged.
50 To (A) is the inflation pressure P _X to a target coal blend than x in FIG. 1 is a 3.2KPa, are examples blended with A~L coal so that the inflation pressure P _X . The arithmetic mean inflation pressure P ₀ of the coal blend at this time is 12.0 KPa when calculated by the above equation (1) using the maximum inflation pressures P _i of the A to L coals.
Next, the inflation pressure P _X of coal blend to which is calculated by the based (2) becomes 3.2KPa. Then, after the carbonized coal was carbonized in a coke oven, the extrusion load peak current when extruded by an extruder was 250 (A), which was the same as in the case of stable operation.

Comparative Example 2 Comparative example 2 is directed to a carbonization chamber having a damaged furnace wall, and is an example in which the same blending coal and the same blending ratio as in comparative example 1 are used. The arithmetic mean inflation pressure P ₀ of the blended coal at this time is the same as that of Comparative Example 1, and is calculated by the above equation (1) using the maximum inflation pressures P _{i of the A} to L coals.
2.0KPa next, inflation pressure P _X of coal blend to which is calculated by the based (2) is 3.2KPa. Then, after the carbonized coal was carbonized in a coke oven, the extrusion load peak current when extruded by an extruder was 290 (A).
It is estimated that there is a possibility that a large load is applied to the furnace wall of the coking chamber and a stop is generated as compared with the case where the stable operation is performed.

(Example 1) Example 1 is an example in which coals A and B of the blended coal were cut in order to reduce the extrusion load peak current 290 (A) in Comparative Example 2 to 250 (A) or less. , to 250 (a) and from the pushing load peak current y in FIG. 1, the inflation pressure P _X of coal blend is 0.8KPa becomes,
Arithmetic mean inflation pressure P of blended coal calculated from equation (2)
₀ becomes 9.6 KPa. Therefore, using the maximum inflation pressures P _{i of the A} to L coals so that the arithmetic mean inflation pressure P ₀ becomes 9.6 KPa, the blending brand and the blending ratio are determined from the above equation (1), , B charcoal was cut. After the carbonized coal was carbonized in a coke oven, the extrusion load peak current when extruded by an extruder was 245 (A), which was almost the same as in the case of stable operation.

Example 2 Example 2 is an example in which the same brand of coal as in Comparative Example 2 was used and the blending ratio of the coal was adjusted.
To (A) is the inflation pressure P _X of coal blend is 0.8KPa
And the arithmetic mean inflation pressure P ₀ of the blended coal calculated from the above equation (2) is 9.5 KPa. For this reason, using the maximum inflation pressures P _{i of the A} to L coals so that the arithmetic mean inflation pressure P ₀ is 9.5 KPa, the mixing ratio of the A to L coals is calculated according to the above equation (1). Are adjusted as shown in FIG. After the carbonization of this blended coal in a coke oven, the extrusion load peak current when extruded by an extruder is 250 (A),
This was almost the same as when stable operation was being carried out.

From the above Examples 1 and 2, it can be seen that extrudability is improved by using a blended coal designed to have a low expansion pressure in a kiln (carbonization chamber) having a furnace wall damage. Therefore, the method for operating a coke oven according to the present invention was found to be very useful.

[0023]

According to the method for operating a coke oven according to the first and second aspects, the brand of coal constituting the blended coal is placed in a coking chamber in which the load of the extruder at the time of extruding the coke cake is higher than a predetermined reference value. And the blending ratio is adjusted to reduce the inflation pressure of the blended coal, and the blended coal charged so that the extrusion load is equal to or less than the reference value in the previous period is carbonized. The press stop of the chamber can be suppressed and the extrudability of the coke cake can be improved,
It can greatly contribute to the stable operation of coke ovens.
In particular, in the method for operating a coke oven according to the second aspect, since the blending ratio is reduced in the order of brands having higher expansion pressures of the blended coal, it is possible to operate the coals largely without being influenced by the supply and demand of coal.

[Brief description of the drawings]

FIG. 1 is a graph showing an extrusion load with respect to a blended coal expansion pressure of each of a normal kiln and a management kiln.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Yoichi Ota 1 Nishinoshima, Oita-shi, Oita F-term in Nippon Steel Corporation Oita Works (reference) 4H012 MA01 MA02

Claims (2)

[Claims] 1. A method of operating a coke oven in which a coal blend containing a plurality of brands of coal is charged into a carbonization chamber of a coke oven and carbonized, and then the carbonized cake is discharged from the carbonization chamber by an extruder. The load of the extruder at the time of extruding the coke cake is adjusted to a carbonization chamber in which the load of the extruder is higher than a predetermined reference value, by adjusting the brand and blending ratio of the coal constituting the blended coal to reduce the expansion pressure of the blended coal. And charging the coke oven so that the extrusion load is equal to or less than the reference value. 2. The method of operating a coke oven according to claim 1, wherein the mixing ratio of the coal blend is reduced in the order of the brand having the highest expansion pressure.