JP3016116B2 - Coal carbonization method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of carbonizing coal by charging raw coal containing water into a coke oven furnace and carbonizing the raw coal.

[0002]

2. Description of the Related Art Production of coke by a coke oven furnace is carried out by heating and carbonizing raw coal containing water charged in a coking chamber through furnace walls on both sides of the coking chamber. In recent years, it has been required to establish a carbonization method capable of increasing the carbonization efficiency and at the same time extending the life of the furnace body and improving the quality of the product coke. Technical development for this purpose is being promoted.

[0003] For example, in order to improve the dry distillation efficiency, the raw coal is pre-dried at 170 to 250 ° C in advance and is usually 8 to 11%.
A preheating coal charging method has been put to practical use in which the moisture content of charged coal is reduced to 0%. This technology improves the coke oven productivity by shortening the time required for carbonization, improves the cokeability by increasing the bulk density of the charged coal and increases the width of the softened molten layer of coal during carbonization, and reduces the amount of heat required for carbonization. Reduction can be achieved. However, a large-scale facility for preheating the charged coal is required, and the bulk density of the charged coal is increased, so that a large expansion pressure is applied to the furnace wall during carbonization, and the furnace wall is damaged. There is a risk. For this reason, the preheated charcoal charging method has not been widely used in general, and is actually used only in some coke plants.

[0004] In order to increase the carbonization efficiency, studies have been made on increasing the width (furnace width) and height (furnace height) of the carbonization chamber. However, this technique is effective when a new coke oven is installed, but cannot be applied to an existing coke oven, and does not lead to improvement in the carbonization efficiency of the existing oven.

[0005] A method of improving the heat transfer property by thinning the furnace wall bricks has been partially put into practical use, but this method may impair the robustness of the furnace body and is not necessarily a recommended method.

On the other hand, regarding the extension of the life of the furnace body,
The repair technology has progressed and has had a great effect. But,
This is a technique for repairing a damaged furnace body, and cannot be said to be a technique for actively extending the life of the furnace body. In order to extend the life of the furnace body, it is conceivable to operate the furnace at a reduced furnace temperature, but the carbonization efficiency is reduced and the coke productivity is deteriorated.

As described above, the improvement of the carbonization efficiency and the extension of the life of the furnace body are in conflict with each other. Therefore, the carbonization efficiency is increased, the life of the furnace body is extended, and the coke quality is improved. In addition, achieving stabilization (reduction in variation) has been a very difficult task.

[0008] In order to solve this problem, a heat-resistant metal or ceramic path is formed from the center of the charcoal column (coking coal) charged into the coking chamber to the outside of the charcoal column. A method of carbonizing while discharging water vapor generated from a portion has been proposed (see JP-A-1-198686).

[0009] Further, the applicant of the present invention has found that when coking coal containing water, the cause of the reduction in carbonization efficiency is the flow of steam generated in the coal seam to the furnace wall side in the early stage of carbonization. After confirming the above, leveling the upper surface of the coking coal charged into the carbonization chamber, insert a hole member into the coal layer from the coal port provided on the furnace, and pull it out to carbonize the coal layer in advance. A dry distillation method in which a bleed hole communicating with a space in the upper part of the room is provided, and then heating is proposed (JP-A-2-145687)
Reference).

[0010] According to these methods, the carbonization time can be shortened, the coke quality (coke strength) can be improved, and the variation can be reduced. Further, since the pressure of the gas containing water vapor in the coal seam does not increase, an excessive load is not applied to the furnace wall, and the life of the furnace body can be extended.

However, in these methods, it is necessary to provide a passage for discharging water vapor, or to newly provide a facility for forming a bleed hole, which requires a large investment. . In addition, in the method of providing the bleed holes, the position of the bleed hole is limited because the position of the bleed hole is limited, and the effect thereof is also limited. Further, in recent years, a humidified coal operation in which the water content of a raw coal is adjusted to about 6%, and then charged into a carbonization chamber to perform dry distillation, has been put into practical use. Even if the bleed holes are opened by inserting the opening member into the coal layer, a part of the coal layer collapses when the bleed holes are pulled out, and it is difficult to form a stable bleed hole.

[0012]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems in the prior art and improves coke quality and stabilizes coke quality (reduction in variation) while achieving both improvement in carbonization efficiency and life extension of a furnace body. The present invention has been made to provide a carbonization method that can achieve the above.

[0013]

Means for Solving the Problems As a result of repeated studies to achieve the above objects, the present inventors have found that a coal or coke having no softening and melting properties is placed on a second coal layer on a raw coal containing water. It has been found that a method for charging and carbonizing as a charge is effective, and has led to the present invention.

The gist of the present invention resides in a method for carbonizing coal described below or shown in FIG.

[0015] In a coal carbonization method performed by charging coking coal (2) containing water into a coke oven (1), a coal or coke which does not have softening and melting properties over the entire area of coking coal is used. A carbonization method for coal, comprising charging a second layer charge (2d) and carbonizing.

In the coal dry distillation method in which a raw coal containing water (2) is charged into a coke oven furnace (1), the dry distillation of the initially charged raw coal proceeds and is caused by a decrease in bulk. A method in which a second layer charge made of coal or coke having no softening and melting properties is charged into the space above the raw coal and carbonized.

The above-mentioned coking coal containing water is usually from 2 to 11
% Of water, and is used as raw coal in the production of coke by a coke oven furnace. Examples of coal corresponding to coal having no softening and melting properties include non-caking coal. The thickness of the second layer charge made of coal or coke having no softening and melting properties (hereinafter, simply referred to as the second layer charge) is desirably 100 mm or more as described later. The space created by the reduction of the coking coal in the other method is preferably 100 mm or more.

[0018]

Hereinafter, the method of the present invention will be described in detail.

The method of the present invention, as described in detail below,
It is characterized in that the flow of steam generated in the early stage of carbonization is directed toward the upper space of the carbonization chamber by charging the second-layer charge at a predetermined thickness onto the charged normal coking coal. There is. Therefore, first, the dehydration behavior of the water contained in the raw coal, which occurs in the actual carbonization process of the coke oven, will be described with reference to the drawings.

FIG. 2 is a longitudinal sectional view in the width direction of a part of the carbonization chamber of the coke oven, and is a view schematically showing the formation of a coal layer, a softened layer and a coke layer during carbonization. As shown in the figure, from the furnace walls 1a, 1a on both sides of the coking chamber of the coke oven 1, a coke layer 2c, a softened layer 2
b, Coal layer 2a is formed. The softening layer 2b is
A layer with high airflow resistance formed during softening and melting of coal, and as the carbonization proceeds and the coke layer 2c becomes thicker, the furnace wall 1a,
From the 1a side, it gradually moves toward the middle of the coal, where the left and right softened layers 2b and 2b are united in the middle of the coal, and disappear when further carbonization proceeds.

FIG. 3 is a longitudinal sectional view in the width direction of the upper part of the carbonization chamber.
It is a figure which shows typically the formation situation of a coal layer, a softening layer, and a coke layer in the middle of dry distillation similarly to FIG. As shown in this figure, also in the upper part of the furnace, the coke layer 2c, the softened layer 2b, and the coal layer 2a are sequentially heated from the upper space 3 side of the carbonization chamber by heating from the furnace wall 1a and receiving radiant heat from the upper space 3. Is formed. That is, as shown in FIG. 5, which schematically shows a longitudinal section in the width direction of the entire carbonization chamber, the coal layer 2a
Exists in a state surrounded by the softening layer 2b, and the coke layer 2c is formed outside the softening layer 2b.

FIG. 4 is a longitudinal sectional view in the width direction of a part of the carbonization chamber.
This is a diagram schematically showing the temperature distribution in the carbonization chamber (solid line in the figure) and the flow of steam from the coal seam 2a (dashed line in the figure) in the early stage of carbonization, and (a) shows the temperature reaching 100 ° C in the middle of the coal. (B) is a case where the entire coal seam 2a is heated to 100 ° C. or more. The moisture contained in the coal seam 2a is
As long as the temperature of the coal seam 2a in the middle part of the coal does not reach 100 ° C. from the start of the carbonization, it is condensed in the middle part of the coal after evaporation as shown by the broken line in FIG. However, when the entire coal seam reaches 100 ° C., it does not condense and is blocked by the softening layer 2b, so that the steam pressure gradually increases and acts as expansion pressure to the furnace walls 1a, 1a on both sides. When the pressure further rises to exceed the airflow resistance of the softening layer 2b, the steam passes through the softening layer 2b and flows out to the furnace walls 1a, 1a as shown by the broken line in FIG. 4 (b).

FIG. 5 is a diagram schematically showing the flow of steam in the coking chamber. The steam generated in the coal bed 2a reaches the furnace walls 1a, 1a on both sides and then becomes a high-temperature coke bed 2c.
The heat flows from the furnace walls 1a, 1a to the upper part of the furnace along the furnace walls 1a, 1a while removing heat. For this reason, coal bed from furnace walls 1a, 1a
The heat flow supplied to 2a is reduced, the carbonization speed is reduced, and the carbonization efficiency is deteriorated. In addition, the gas containing water vapor exerts an expansion pressure on the furnace walls 1a, 1a, which adversely affects the furnace body.

The cause of the flow of steam as described above is that the softened layer 2b formed by coal softening and melting has much higher airflow resistance than the coal layer 2a and the coke layer 1c.
This is because the upper part of the coal layer 2a is also covered with the softened layer 2b, and the flow of water vapor does not occur above the coal layer 2a.

In the method of the present invention, the raw coal containing water is charged as described above, and then the second-layer charge is charged thereon and carbonized, so that the upper part of the furnace is softened. The layer 2b is not formed, and the steam generated in the early stage of carbonization flows toward the upper space 3 of the carbonization chamber.

FIG. 1 is a longitudinal sectional view of the entire carbonization chamber in the width direction, and is a view schematically showing the flow of steam during carbonization when coal is carbonized by the method of the present invention. As shown in this figure, since the second layer charge 2d is charged on the raw coal 2 containing water, the softened layer 2b is not formed on the upper part of the raw coal. As a result, the flow of steam in the coking coal goes to the upper space 3 direction of the furnace, and heat is not removed from the high-temperature coke layer 2c and the furnace walls 1a, 1a, so that dry distillation is promoted. There is no fear that the furnace wall will be damaged because the expansion pressure by the gas containing water vapor does not act. Since the carbonization temperature increases, the coke quality (coke strength) can be improved.

[0027] The second charged into the upper part of the coking coal containing water
As the layer charge, any material may be used as long as it does not affect the dry distillation of coal, but coal having no softening and melting properties (for example, non-coking coal) or coke is preferable.

The particle size of the second layer charge is to homogenize the gas flow from the lower moisture-containing coal layer 2a (coking coal) and uniformly dry-evaporate the entire coal layer (coking coal) in the coking chamber. On 25
mm or less, and the lower limit of the particle size is not particularly limited. Particles having substantially the same particle size as the lower coal layer (coking coal) are more preferable because the gas flow can be made more uniform. Coke powder obtained by normal coke operation (particle size less than 3 mm
(100%) does not require a new pulverization at the time of use, which is advantageous in terms of economy.

The thickness of the second layer charge varies depending on the furnace structure, but is preferably 100 mm or more. this is,
During the period in which the water from the coking coal is being evaporated (dewatered), that is, after charging the coking coal into the coking chamber (furnace), during the period until the softened layer coalesces at the center in the furnace width direction. During the corresponding period, the distance that the softening layer travels on the side of the furnace is less than 1/2 of the furnace width, but the heating speed at the top of the furnace is usually less than this, and Thickness of object is 100 mm
With the above, a softened layer is not formed on the upper part of the coking coal in the furnace until the dehydration is completed, and the flow of steam generated from the coking coal in the direction of the upper space of the coking chamber is prevented. Because there is no.

The upper limit of the thickness of the second layer charge does not need to be set from the viewpoint of not forming a softened layer on the upper part of the raw coal, but if the thickness is increased, the quality as coke for blast furnace is obtained. Coke production is reduced. Therefore, the thickness of this layer is preferably at least 100 mm and as close as possible to 100 mm.

As a method for charging the second layer charge into the carbonization chamber, any method can be used as long as it can be charged with a thickness of 100 mm or more. After that, a method of charging with another coal-charging vehicle, a method of attaching a hopper for charging the second-layer charging material to a coal-charging vehicle auxiliary hopper, a method of charging from a leveler opening, and the like are preferable. is there.

The part of the coking coal charged into the furnace, which is several hundred mm from the top, is a part of low coke quality even in ordinary dry distillation and is not used as blast furnace coke. Even if it is applied to the production of, its productivity does not decrease. In addition, the method of the present invention can be applied only to a portion where the carbonization is delayed, for example, in accordance with the performance of a coke oven, such as an upper central portion in the oven.

As another embodiment of the method of the present invention, the carbonization of the initially charged coking coal proceeds, and the second layer charge is charged into the space above the coking coal caused by the decrease in the height in the furnace height. You can also. In this method, after the upper surface of the charged coking coal is evenly leveled by a leveler, dry distillation is performed, and the second-layer charging material is charged into the space above the coking coal caused by the reduction in bulk. After leveling evenly with a leveler,
Perform carbonization. Accordingly, there is an effect that the charged amount of the raw coal is increased as compared with the conventional method or the above method.

FIG. 6 is a diagram showing the relationship between the carbonization time of coal and the rate of bulk reduction. It can be seen that the charged coking coal has been reduced in volume by about 5% 2 hours after carbonization. This amount can be measured by lowering a rod with a plate from the coking coal inlet onto the coking coal, and charging the second-layer charge only when the bulk loss exceeds 100 mm It is preferable to carry out.

[0035]

【Example】

[Example 1] 250 kg test coke oven with the same furnace width as the actual furnace
(Carbonization room: width 0.45m x length 1.0m x height 1.2m), and using normal coking coal [particle size: less than 3mm (-3mm) 83%] used in actual operation with a moisture of 8.2% After charging the coal from the furnace top so that the coal height is 900 mm and leveling it,
On top of this, coke breeze (100% of -3 mm, method 1 of the present invention) or non-coking coal A shown in Table 1 (method 2 of the present invention)
Was loaded from above with a thickness of 100 mm.

[0036]

[Table 1]

Then, dry distillation was performed at a furnace wall temperature of 1170 ° C., and the middle part of the coal (center in the furnace width direction, 0.5 m in the length direction, and 0.5 m in the height direction)
900 ° C from the start of carbonization with a thermocouple installed at
The time to reach was measured. Also, from the start of carbonization
After 22.5 hours, the coke cake was discharged as it was, cooled with nitrogen gas, and then samples were taken from a total of 9 points, 3 points in the furnace width direction and 3 points in the furnace height direction, and the rotational strength test specified in JIS K 2151 The coke strength was measured by the method. For comparison, a test was also performed on a conventional method (conventional method 1) in which no coke breeze or non-coking coal was charged. Table 2 shows the test results.

[0038]

[Table 2]

As can be seen from Table 2, the methods of the present invention 1, 2
According to the results, the time required for the middle part of the coal to reach 900 ° C. is reduced by about 1.5 hours as compared with the conventional method 1, and a significant effect of promoting carbonization is recognized. In addition, the coke strength was improved and the variation was reduced, indicating that the method of the present invention is also effective for improving and stabilizing coke quality.

[Example 2] Coking coal used in actual operation with moisture adjusted to 2.3% and 5.8% (83% for -3mm)
A test was performed under the same conditions as in Example 1 using non-caking coals B (invention method 4) and C (invention method 3) shown in Table 3 which were also air-dried. However, the time from the start of carbonization to the discharge of the coke cake depends on the water content of the non-coking coal used.
18 hours for 2.3% and 20 hours for 5.8%.
For comparison, tests were also performed on conventional methods (conventional methods 2 and 3) in which coke breeze and non-coking coal were not charged. Table 4 shows the test results.

[0041]

[Table 3]

[0042]

[Table 4]

As can be seen from Table 4, in the method 4 of the present invention, dry distillation is promoted and coke quality and stability are improved as compared with the conventional method 3 even when the charged coal (raw coal) moisture is low. .

Embodiment 3 FIG. 7 is a longitudinal sectional view showing the upper part of a coke oven used in this embodiment. FIG. 7 (a) shows a state in which raw coal is charged and leveled, and then the second layer charge is charged. (B), after charging the second-layer charge on coking coal,
In the case of leveling, (c) shows a case in which coking coal is charged, carbonization is advanced, then leveling is performed, the second layer charge is charged, and leveling is performed again.

A furnace height of 7125 mm having a furnace upper part shown in FIG.
Using a coke oven having a carbonization chamber with a furnace length of 16500 mm and a furnace width of 460 mm, coking coal A having a water content of 9.2% shown in Table 5 was charged into the carbonization chamber, and further coke breeze (-3 mm was used). 100%) using another coal-equipped car and charging and leveling,
The carbonization was performed under operating conditions of an average flue temperature of 1210 ° C. and an average carbonization time of 22 hours (Method 5 of the present invention).

[0046]

[Table 5]

The temperature until the coke temperature reaches 900 ° C. with a thermocouple (5) installed at the center of the furnace width from the second coal mouth (4-2) and at a height of 2, 4, or 6 m from the furnace bottom. The time was measured. At the first, third and fourth coal mouths (4-1, 4-3, 4-4), an iron frame was hung at a height of 2, 4, and 6 m from the furnace bottom, and coking coal was charged. After carbonization, the coke cake was extruded, the coke in the frame was recovered from the wharf, and the coke strength was measured. Furthermore, the temperature of the riser 6 at the beginning of the carbonization and the extrusion current at the time of discharging the coke (out of the kiln) were measured.

The charging amount of coke breeze was 3 per room of the carbonization room.
Tons (750 kg per coal port), equivalent to an average thickness of 400 mm. For comparison, the same measurement was performed in a test by the conventional carbonization method (conventional method 4). Table 6 shows the test results.

[0049]

[Table 6]

As is apparent from Table 6, in the method of the present invention, the time required to reach 900 ° C. is shortened by about 1.2 hours as compared with the conventional method, so that the carbonization promoting effect is large and the carbonization temperature of coke rises. Coke strength has improved and its variability has been reduced. Furthermore, since the extrusion current was slightly reduced as compared with the conventional method, it was suggested that the coal expansion pressure during carbonization was reduced and the coke cake was sufficiently separated from the furnace wall. It can be said that the method is also effective for furnace wall maintenance. In the method of the present invention, the riser temperature in the early stage of carbonization is reduced by nearly 40 ° C. as compared with the conventional method, but this is because steam generated in the coal bed during carbonization passes through the vicinity of the furnace wall in the method of the present invention. Instead of flowing directly from the coal seam into the upper space of the furnace, suggesting that the heat from the furnace wall is being effectively used for carbonization of coke.

Example 4 Using the same coke oven as used in Example 3, raw coal B having a moisture content of 8.5% shown in Table 7 was charged into a carbonization chamber, and as shown in FIG. 7 (c). In Leveler (7)
After leveling the surface to the position shown in (a), carbonization was performed, and a rod with a plate was lowered from the coal charging port to the upper surface of the raw coal during carbonization, and the amount of bulk reduction was measured.

[0052]

[Table 7]

When the amount of bulk reduction of the coking coal reached 100 mm (the position indicated by (b) in FIG. 7 (c)), the coke breeze (-
(3% 100%) was charged using another coal-charging truck and leveled again (Method 8 of the present invention). Then, carbonization is performed for 22 hours at an average flu temperature of 1200 ° C, and the coke temperature is reduced.
Coke strength was measured in the same manner as in Example 3 until the temperature reached 900 ° C.

When the bulk reduction of the raw coal reached 100 mm, the non-coking coal D shown in Table 8 was charged as the second layer charge.
After charging 1000 kg (corresponding to an average thickness of 200 mm), the same test as above was performed (Method 9 of the present invention). Inventive methods 6 and 7
As shown in FIG. 7 (a), raw coal was charged and leveled, and then a second-layer charge was charged. For comparison, a test was conducted by a conventional carbonization method (a method in which the second-layer charge was not charged on top of the raw coal, conventional method 5), and the same measurement was performed. Table 9 shows the test results.

[0055]

[Table 8]

[0056]

[Table 9]

As is clear from Table 9, in the methods 6 to 9 of the present invention, the variation in the time required for the middle portion of the coal to reach 900 ° C. was reduced as compared with the conventional method 5. In addition, the coke strength was improved as well as the coke strength was reduced, indicating that all the methods of the present invention are effective in improving and stabilizing coke quality.

[0058]

According to the method of the present invention, by using an existing coke oven, the coke quality is improved and the stabilization (reduction in variation) is achieved while achieving both the efficiency of dry distillation and the life extension of the furnace body. be able to. It does not require a large amount of capital investment and is excellent in economy.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view in the width direction of the entire carbonization chamber, schematically showing a flow of steam during dry distillation in the present invention.

FIG. 2 is a longitudinal cross-sectional view of a part of a carbonization chamber in a width direction, schematically illustrating a formation state of a coal layer, a softened layer, and a coke layer during carbonization.

FIG. 3 is a longitudinal sectional view in the width direction of an upper portion of a carbonization chamber, schematically showing a state of formation of a coal layer, a softened layer, and a coke layer during carbonization.

FIG. 4 is a longitudinal sectional view of a part of the coking chamber in a width direction, schematically showing a temperature distribution in the coking chamber (solid line in the figure) and a flow of steam from the coal seam (dashed line in the figure). It is.

FIG. 5 is a diagram schematically showing a flow of water vapor in a carbonization chamber.

FIG. 6 is a diagram showing the relationship between the carbonization time of coal and the rate of bulk reduction.

FIG. 7 is a longitudinal sectional view showing an upper structure of the coke oven;
(a) When the second layer charge is charged after charging and leveling of coking coal, (b) is leveling after charging the second layer charging on coking coal In the case (c), the raw coal is charged, the carbonization proceeds, leveling is performed, the second-layer charged material is charged, and leveling is performed again.

[Explanation of symbols]

1: Coke oven 1a: Furnace wall 2:
Coking coal 2a: Coal bed 2b: Softened bed 2c:
Coke layer 2d: Second layer charge 3: Upper space 4:
Charging port 5: Thermocouple 6: Riser 7:
Leveler

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-60-23479 (JP, A) JP-A-60-221487 (JP, A) JP-A-7-228873 (JP, A) 125365 (JP, U) (58) Field surveyed (Int. Cl. ⁷ , DB name) C10B 57/02 C10B 47/10 C10B 31/02

Claims (1)

(57) [Claims] 1. A method for dry-drying coal by charging coking coal containing water into a coke oven furnace, wherein the whole area of coking coal is
Second SoSo carbonization process of coal characterized by dry distillation was charged the initial charge consisting of coal or coke having no thermal plasticity over.