JP2001214171A - Method of operating coke furnace - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce and control the expansion pressure of a blended coke steadily and surely under the limited allowable value for avoiding a damage of a coke furnace and to prepare a coke having a strength of a certain value or more by using a simple method to reduce the expansion pressure instead of increasing a blending ratio of a brand of coke having a low expansion pressure when the expansion pressure of a conventional blended coke is estimated from the arithmetical mean of expansion pressure of each brand of cokes constituting the blended coke. SOLUTION: In this method of operating a coke furnace using a blended coke of two or more brands of cokes, a specific equation is deducted from the arithmetical mean of expansion pressure of each brand of cokes constituting the blended coke, the blending ratio of non-slightly-caking coke, the whole expansion coefficient of a blended coke of caking cokes only, and the addition ratio of a caking additive. The expansion pressure of the blended coke is calculated from this equation. Brands of cokes to be blended, the blending ratio and the addition ratio of a caking additive are adjusted to keep this calculated expansion pressure of the blended coke under a predetermined limited allowable value of the coke furnace.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method of operating a coke oven, and more particularly to a method of operating a coke oven for reducing damage to the coke oven and improving coke extrusion.

[0002]

2. Description of the Related Art In the process of producing coke by carbonizing coal in a carbonization chamber of a coke oven, the coal expands due to heating and exerts a pressure on the furnace wall of the coke oven. Called inflation pressure. If the expansion pressure becomes abnormally high, the coke oven wall is directly damaged and becomes inoperable, and the resistance (extrusion resistance) increases when the coke is discharged from the carbonization chamber to the outside of the furnace (during extrusion). Excessive load on the furnace wall may cause damage to the furnace wall. For this reason, it is an important subject to control the expansion pressure below the permissible limit value of the coke oven damage in the operation of the coke oven. In particular, in recent years, the coke ovens have deteriorated and the furnace body strength has decreased, lowering the permissible limit. In addition, the introduction of coal pretreatment technology such as the humidified coal method has recently introduced coal charging in the coke oven coking chamber. As the bulk density increases and the inflation pressure is on the rise, managing the inflation pressure becomes an increasingly important issue for prolonging the life of coke ovens.

Conventionally, the expansion pressure cannot be measured in an actual coke oven, and therefore, the coal content represented by the volatile matter, carbon content and average reflectance of coal, or the viscosity represented by the total expansion rate and the maximum fluidity, etc. Attempts have been made to estimate the inflation pressure using the cementability parameters, but there was a difference between the inflation pressure estimated from these coal properties alone and the actual inflation pressure, and it was not possible to estimate the inflation pressure at a practical level. . Therefore, Japanese Patent Application Laid-Open No. 5-255
As disclosed in Japanese Patent No. 670, prior to charging a predetermined blended coal into an actual coke oven, for example, using a special test dry distillation furnace having a movable wall on one side called a movable wall furnace,
In advance, the expansion pressure at the time of carbonization of a predetermined coal blend is measured, or as proposed by the present inventors in Japanese Patent Application Laid-Open No. 11-302661, each brand coal constituting the coal blend is subjected to a test carbonization furnace in advance. The expansion pressure is measured, and the expansion pressure of the blended coal is estimated based on the arithmetic mean value of the expansion pressure of each brand coal measured beforehand for the blended coal, and the expansion pressure of the blended coal causes damage to the furnace wall. The blending brand and proportion of coking coal were adjusted so as to be below the allowable limit pressure.

[0004]

However, the method disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 5-255670, in which the expansion pressure is measured in advance in a test furnace for each coal blend and controlled, is used to adjust the coke quality. If the coking coal mix suddenly changes, or if there is a sudden problem in the coking coal procurement or coking coal transport equipment and the coking coal blend must be suddenly changed, it is not possible to respond promptly. . In addition, in order to quickly respond to such a sudden change in the coking of the coking coal, the expansion pressure is measured in advance in a test furnace for all possible coking coal mixing combinations, and an expansion pressure map is created. The thing is
Since there are many types of coal blends, a great deal of labor and time are required, which is not practical.

The inventors of the present invention described in Japanese Patent Laid-Open No. 11-3
The expansion pressure of coal blend is estimated based on the arithmetic average of the expansion pressure of each brand coal measured with a test furnace proposed in Japanese Patent Publication No. 02661 in advance, and the expansion pressure is controlled by adjusting the blending of raw coal. The method for performing the above is described in
Compared to the method disclosed in Japanese Patent Publication No. 70, it is possible to respond quickly when changing the blending of coking coal, and this is a very effective method, but the blending is restricted in order to maintain coke quality such as coke strength. There was a problem. That is, generally, coal having a high expansion pressure is a caking coal having a low volatile content and a low inert content, but since these coals are also important coals for maintaining coke strength, in some cases, In some cases, it is difficult to restrict the mixing ratio of these coals while maintaining coke strength.

According to the present invention, when estimating the inflation pressure of a blended coal from the arithmetic mean of the inflation pressure of each brand coal constituting the conventional blended coal, instead of increasing the blending ratio of plain coal having a low expansion pressure, In addition, the expansion pressure is reduced by using a simple expansion pressure reduction method, and the expansion pressure is controlled stably and reliably to an allowable limit value at which the coke oven is not damaged, and a coke having a certain strength or more is produced. The purpose of the present invention is to provide a coke oven operating method.

[0007]

The gist of the present invention is as follows: (1) In a method of operating a coke oven using a blended coal blended with a plurality of brands of coal, the maximum of coal of each brand constituting the blended coal is described. Arithmetic mean value of inflation pressure (Σp _i x _i ),
The formula (1) is obtained from the blending ratio (X) of the non-slightly caking coal, the total expansion ratio (TD) of the blending coal containing only the caking coal, and the binder addition ratio (y).
The blending coal expansion pressure (Px) is calculated by the following formula, and the brand, blending ratio and binder addition rate of the coal are set so that the calculated blending coal expansion pressure (Px) is equal to or less than a predetermined allowable limit pressure of the coke oven. The method of operating a coke oven characterized by adjusting the temperature. _{P x = [a · Σp i} x i -b · Σp i x i · (X + c · X 2) · {1 + 1 / (d · TD + e)} + f] · (1-g · y (1) where P _{x is} the estimated inflation pressure (kP) of coal blend containing X% non-coking coal
a) p _i : Maximum expansion pressure of plain coal i (kPa) x _i : Mixing ratio of plain coal _i (-) Σp _i x _i : Maximum expansion pressure of each plain coal _i constituting blend coal Arithmetic average value (kPa) X: Blended ratio of non-coking coal (%) TD: Total expansion rate of blended coal containing only caking coal (%) y: Binder addition ratio per coal (%) a, b, c, d, e, f, g: constants obtained from experiments

(2) One component in which the binder is soluble in hexane
The method for operating a coke oven according to the above (1), characterized in that the coke oven contains 0 wt% or more and 85 wt% or more of carbon. (3) The method for operating a coke oven according to the above (2), wherein the binder comprises tar. It is in.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The present inventor has previously described Japanese Patent Laid-Open No. 11-3
Based on the method of reducing the inflation pressure proposed in Japanese Patent No. 02661,
As a result of intensive studies on a method for reducing the expansion pressure without reducing the coke strength, which is a conventional problem, it was found that it is effective to add a binder to the blended coal charged into the coke oven. Was. Coal is softened and melted in the carbonization process and then re-solidified to form coke. The cause of the expansion pressure is the pressure of the pyrolysis gas of coal trapped in the softened and melted coal layer. Since the viscosity of the softened and melted coal layer is very high, the generated gas cannot easily escape and is trapped inside. As a result, the pressure of the gas increases, and this pressure acts on the coke oven wall as expansion pressure via the coke layer. Therefore, if the pressure of the gas in the coal layer that has been softened and melted is reduced, the expansion pressure can be reduced. The inventors have found that by adding a binder, the pressure of the gas in the softened and melted coal layer decreases. This is presumably because the viscosity of the coal layer softened and melted was reduced by adding the binder.

The inventor has found that the expansion pressure decreases in proportion to the amount of the binder added. For example, FIG. 1 shows the relationship between the binder addition rate and the blending carbon expansion pressure. When the binder is tar, the expansion pressure becomes 1 when 1% by weight of coal is added.
The addition of 0% and 3% by weight resulted in a 30% reduction. The inventor has also found that the expansion pressure reduction effect is saturated even if the addition ratio is increased to a certain value (the upper limit of the effect saturation). FIG.
As shown in the above, when the binder is tar, the effect of reducing the expansion pressure does not change even if the addition rate is increased to 5% or more.

The present inventor has previously described Japanese Patent Application Laid-Open No. H11-30266.
In Japanese Unexamined Patent Publication No. 1, the arithmetic mean value of the maximum inflation pressure (Σp _i x _i ) of each brand of coal constituting the blended coal, the blending ratio of non-coking coal (X), and the blending of caking coal only From the total expansion coefficient (TD) of the coal, the blended coal expansion pressure is calculated by the following equation (2),
A method of reducing the expansion pressure for adjusting the brand and the mixing ratio of the coal so that the calculated blended coal expansion pressure is equal to or less than a predetermined allowable limit pressure of the coke oven was proposed.

P _x '= a · Σp _i x _i -b · Σp _i x _i · (X + c · X ² ) · {1 + 1 / (d · TD + e)} + f (2) P _x ': Estimated expansion pressure (kP) of blended coal containing X% non-coking coal
a) p _i : Maximum expansion pressure of plain coal i (kPa) x _i : Mixing ratio of plain coal _i (-) Σp _i x _i : Maximum expansion pressure of each plain coal _i constituting blend coal Arithmetic average value (kPa) X: Blending ratio of non-coking coal (%) TD: Total expansion rate of coking coal with caking coal only (%) a, b, c, d, e, f: From experiments Obtained constant

However, Japanese Patent Application Laid-Open No. H11-302
No. 661 discloses a composition of non-coking coal as shown in FIG. 2 showing the relationship between the mixing ratio of non-coking coal and the expansion pressure of coking coal, and the relation between the mixing ratio of non-coking coal and coke strength. Although the expansion pressure of blended coal decreases by increasing the ratio,
The coke strength is also reduced (especially when the non-sintered coal blending ratio is 40
%), There is a problem that the strength required for use in a blast furnace cannot be obtained. In the present invention, based on the above formula (2), a predetermined amount of a binder is further added based on the relationship of the following formula (1) to reduce the coke strength to below the allowable limit pressure without lowering the coke strength. The expansion pressure can be reduced.

P _x = P _x '· (1-g · y) = [a · ap _i x _i -b · Σp _i x _i · (X + c · X ² ) · {1 + 1 / (d · TD + e)} + f] ・ (1-g ・ y) ・ ・ ・ ・ ・ ・ ・ (1) where P _x : Estimated expansion pressure (kP) of coal blend containing X% non-coking coal
a) p _i : Maximum expansion pressure of plain coal i (kPa) x _i : Mixing ratio of plain coal _i (-) Σp _i x _i : Maximum expansion pressure of each plain coal _i constituting blend coal Arithmetic average value (kPa) X: Blended ratio of non-coking coal (%) TD: Total expansion rate of blended coal containing only caking coal (%) y: Binder addition ratio per coal (%) a, b, c, d, e, f, g: constants obtained from experiments

That is, in the present invention, the arithmetic mean value (Σp
_i x _i ), the blending ratio of non-coking coal (X), the total expansion coefficient (TD) of the blending coal containing only caking coal, and the binder addition ratio (y) according to the above formula (1) The coal expansion pressure is calculated, and the brand, blending ratio, and binder addition rate of the coal may be adjusted so that the calculated blended coal expansion pressure is equal to or less than a predetermined allowable limit pressure of the coke oven. As the binder, a component containing 10% by weight or more of a component soluble in hexane and having a carbon content of 8% is used.
A binder of 5 wt% or more may be used. Examples of such a binder include tar.

FIG. 3 shows the relationship between the blending ratio of non-fine caking coal and the blending carbon expansion pressure when 3% of tar is added as a binder, and the relationship between the blending ratio of non-fine caking coal and coke strength. It is the figure which compared. From the figure, it can be seen that by adding a binder according to the present invention, the expansion pressure can be reduced while maintaining the required strength of coke up to a non-sintered coal mixing ratio of 70%. In the present invention, the blending ratio of the non-coking coal of the blended coal is adjusted according to (1) depending on the required strength and the required expansion pressure of the coke. Critical expansion pressure): 10 kPa or less,
In order to obtain coke with a coke strength (drum strength index) of 83 or more, the blending ratio of non-coking coal of blended coal is 70%.
It is preferable to set the following. If the blending ratio of the non-coking coal of the blended coal exceeds 70%, the expansion pressure is reduced and good coke extrusion properties can be obtained, but the coke strength required for use in a blast furnace cannot be obtained. It is.

[0017]

EXAMPLES Comparative Example 1 in Table 1 is an example of a composition in which the estimated expansion pressure P _{x of the} coal blend composed of coals A to G is closer to the allowable limit expansion pressure (10 kPa) of the coke oven. Here, the equation (1) was used to calculate the estimated inflation pressure, and the following values were used as the coefficients in the equation (1). a '= 0.795064, b' = 0.004087, c '= -0.0040476, d' = 0.00986, e '= -0.2112, f' = -5.9394, g = 0.1

[0018]

[Table 1]

In Comparative Example 1, the estimated value of the inflation pressure of the coal blend was 8.1 kPa. Then, when the blended coal is carbonized in a coke oven and then extruded with an extruder, the extruded load peak current is 285 A, which is not more than the allowable upper limit of the extruded load peak current value of 300 A or less. It is estimated that a large load is applied to the furnace wall of the coking chamber. Coke strength is JI
The drum strength index measured by the drum strength test method described in SK2151 was 84.5, indicating a sufficient strength.

Comparative Example 2 has a high maximum expansion pressure A in the blended coal of Comparative Example 1 such that the estimated inflation pressure P _x of the blended coal is sufficiently lower than the allowable limit expansion pressure (10 kPa) of the coke oven.
This is an example in which the blending is adjusted so as to reduce the coal and increase the G coal having a low maximum inflation pressure. The estimated inflation pressure of the blended coal of Comparative Example 2 was 3.6 kPa, which was lower than that of Comparative Example 1,
After the carbonized coal was carbonized in a coke oven, the extrusion load peak current when extruded by an extruder was also 250 A, and the allowable upper limit of the extrusion load peak current value was 300 A or less, and the operation was stable. However, the drum strength index was as low as 83.5, and as a result, although the expansion pressure could be reduced as compared with Comparative Example 1, the strength was significantly reduced.

The invention example is the same as the comparative example 1 except that 5% by weight of tar is added as a binder, without changing the composition of the coal in the coal blend as in the comparative example 2. 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 much lower than the allowable upper limit of the extrusion load peak current value of 300 A, and stable operation was possible. The drum strength index was 84.8, indicating that the coke had sufficient strength. From the above examples, the present invention maintains the required strength of coke,
Further, it can be seen that it is possible to improve the coke extrusion property by reducing the expansion pressure.

[0022]

According to the present invention, the expansion pressure can be reduced to a target value or less while maintaining coke strength by a simple method, and stable coke oven operation can be continued without damaging the coke oven wall. As a result, the cost for repairing the coke oven is reduced, and production troubles due to clogging can be avoided, and the economic effect is extremely large.

[Brief description of the drawings]

FIG. 1 is a graph showing a relationship between a binder addition rate and a blended carbon expansion pressure.

FIG. 2 is a diagram showing the relationship among the blending ratio of non-coking coal, the blending coal expansion pressure, and the coke strength.

FIG. 3 is a diagram showing the relationship among the blending ratio of non-fine caking coal, the blending coal expansion pressure, and coke strength when 3% of tar is added as the binder of the present invention.

Claims (3)

[Claims] 1. A method of operating a coke oven using a blended coal blended with a plurality of brands of coal, wherein the arithmetic mean value (Σ) of the maximum expansion pressure of each brand of coal constituting the blended coal.
p _i x _i), the blending ratio of non- or slightly-caking coal (X), and coking coal only the total expansion ratio of the coal blend in (TD), blended coal from caking agent addition rate (y) by equation (1) The expansion pressure (Px) is calculated, and the brand, blending ratio and binder addition rate of the coal are adjusted so that the calculated blended coal expansion pressure (Px) is equal to or less than a predetermined allowable limit pressure of a coke oven. A method of operating a coke oven characterized by the above-mentioned. _{P x = [a · Σp i} x i -b · Σp i x i · (X + c · X 2) · {1 + 1 / (d · TD + e)} + f] · (1-g · y (1) where P _{x is} the estimated inflation pressure (kP) of coal blend containing X% non-coking coal
a) p _i : Maximum expansion pressure of plain coal i (kPa) x _i : Mixing ratio of plain coal _i (-) Σp _i x _i : Maximum expansion pressure of each plain coal _i constituting blend coal Arithmetic average value (kPa) X: Blended ratio of non-coking coal (%) TD: Total expansion rate of blended coal containing only caking coal (%) y: Binder addition ratio per coal (%) a, b, c, d, e, f, g: constants obtained from experiments 2. A composition in which a binder is soluble in hexane in an amount of 10 w
The method for operating a coke oven according to claim 1, wherein the content is at least t% and the content of carbon is at least 85 wt%. 3. The method for operating a coke oven according to claim 2, wherein the binder comprises tar.