JPH02258891A - Production of coke - Google Patents

Abstract

PURPOSE:To attain shortening of carbonization time, use of a large amount of non-pulverized caking coal, reduction in flue temperature, etc., by adjusting caking property of charging coal, adding a binder to the coal to form cob coal, charging the whole amount of the cob coal to a coke oven and carbonizing. CONSTITUTION:Caking property of charging coal is adjusted to 40-80 (preferably 50-70) caking power index CI corresponding to size of cob coal and a binder is added to the coal to make cob coal having >=30cm<3> (preferably >=50cm<3>) size. Then the cob coals of various shapes are made into a shape wherein two or more cob coals connected, thickness of connecting part is <=75% the maximum thickness and the longest diameter is >= twice thickness and the cob coal is fed to a coke oven of horizontal furnace type and carbonized.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a coke manufacturing method using a current horizontal chamber type coke oven.

C. Prior Art] The current chamber furnace coke production method has been improved over the century and a half since its invention, and is a nearly perfected process, but it suffers from low production elasticity and strong caking coal. is indispensable, and the narrow range of raw material selection is considered to be a drawback. In order to improve this problem even a little, various studies are being carried out in various places, and various methods have been proposed. The production elasticity of current indoor coke ovens is low because the coal charged to the coke oven is mainly pulverized coal that has been crushed to 80-90% less than 3 mm. In order to increase the density of coke and improve the quality of coke, some of the charged coal is agglomerated and mixed with powdered coal before being charged into the coke oven, but in any case, the heat transfer in the coking chamber is conducted. The only way to increase production speed and increase production flexibility is to increase the flue temperature, but the flue temperature naturally has a limit due to the material of the brick. Furthermore, if the flue temperature is lowered from the viewpoint of thermoeconomics, the carbonization time will be significantly extended due to heat transfer characteristics, and the current indoor furnace method is a coke production method with little flexibility.

On the other hand, with regard to the range of raw material selection, various methods have been proposed, such as the briquette blending method, stamping method, dry coal charging method, etc., and efforts have been made to expand the range of raw material selection. By increasing the packing density, the caking properties of the coking coal are effectively used, and the amount of non-slightly caking coal is blended accordingly.The amount of non-slightly caking coal is at most 20 The limit is about %. In addition, these methods have their limits because the bulk density in the coking chamber increases, which eliminates the gap between the furnace wall and the coke cake when coked, increasing the extrusion resistance, and eventually making extrusion impossible. In the case of the method, the extrusion current may exceed the limit value at a briquette ratio of 30% during high operation rate operation, so the maximum blending amount of agglomerated coal is set at about 30%.

The process that uses the largest amount of non-slightly coking coal is the molded coke process, and various molded coke production methods have been proposed and developed in various places.

Most molded coke manufacturing methods use a shaft furnace, but some methods have been proposed in which molded coke or regular coke is produced by charging molded coal into the current chamber-type coke oven. A method disclosed in JP-A-51-5401 in which pulverized coal and briquette coal are charged in that order and carbonized to produce briquette coke and regular coke at the same time; JP-A-52-1030, in which the molten coal is charged into the carbonization chamber opposite to the extruder side and carbonized to produce molten coke and regular coke at the same time.
The method of Publication No. 3, characterized in that normal blended coal for coke is charged through charging holes on both sides, and molten coal for fused coke is charged through the remaining charging hole. -11
The coke disclosed in Japanese Patent Laid-Open No. 54-61201, which is characterized in that the method of charging coking coal is disclosed in Japanese Patent Publication No. 101, and that briquette coal is first charged, and then powdered coal is charged on top of the briquette coal, followed by carbonization. There are manufacturing methods, etc. In all of these methods, pulverized coal is charged to fuse the briquettes during the carbonization process and make extrusion easier, so conduction heat transfer is the main form of heat transfer, and the effect of the briquette coal composition is Although this increases the blending amount of non-slightly coking coal, the carbonization rate slows down as the charging density increases, and this does not lead to improved productivity.

In addition, regarding the shape of briquette coal, the larger the size, the more difficult it becomes to mold the coal to a uniform density within the precincts, and shrinkage cracks are more likely to occur during heating. Kaisho 51-111803
As proposed in the publication, there are various types of briquette coal, but all of them have a concave center. In the case of such briquette coal, it is effective in terms of the uniformity of density within the boundary in terms of moldability, but the effect is small in terms of suppressing shrinkage cracking during heating.Shrinkage cracking occurs due to temperature differences within the boundary during solidification and shrinkage during the carbonization process. This occurs when thermal strain occurs within the coke structure and the stress exceeds the strength of the coke structure.

The degree of stress depends on the temperature gradient within the area and the area of the isothermal zone (numerically proportional to the diameter of the briquette).
This is why even if the temperature gradient within the precincts is the same, the larger the type of molten coal, the more likely it is to break. Therefore, in order to suppress shrinkage cracking, it is important to reduce the area of the isothermal zone within the temple grounds. In the above-mentioned Japanese Unexamined Patent Publication No. 51-111803, the isothermal zone area is hardly reduced, and the effect of suppressing shrinkage cracking is not expected due to the shape of the briquette, and some further measures are required.

[Problem to be solved by the invention] The present invention solves the problem without modifying the current indoor coke oven.
The aim is to shorten the carbonization time, use a large amount of non-slightly caking coal, lower the flue temperature, etc. by pre-treating the charged coal and operating methods.

[Means and effects for solving the problems] The present invention aims to solve the above problems by agglomerating charged coal and charging it into a coke oven. The gist of this method is to adjust the caking properties of the charged coal to a range of 40 to 80 according to the size of the agglomerated coal in a horizontal chamber type coke oven, and then add a binder to create agglomerates of 30 cm3 or more. This coke manufacturing method is characterized by forming coal into coal, charging the entire amount into a coke oven, and carbonizing it. Furthermore, two or more pieces of agglomerated coal of various shapes are connected, and the agglomerated coal is charged into a coke oven and carbonized, with the thickness of the connected part being 75% or less of the maximum thickness and the longest diameter twice the thickness. This is a coke manufacturing method characterized by the following. In other words, the present invention uses radiation heat transfer and convection heat transfer by generated gas in addition to conduction heat transfer when charging powdered coal to increase the carbonization rate, shorten the carbonization time, and agglomerate the charged coal.・The aim is to make effective use of the caking properties of coal by compacting it, and to use a large amount of non-slightly caking coal. Furthermore, in the present invention, if the carbonization time is the same as in the case of pulverized coal charging in the current room furnace method, the flue temperature can be reduced accordingly.

The problem is how to prevent the coke cake from collapsing in the coking chamber during extrusion and making it impossible to extrude, and how to properly fuse the agglomerated coal to each other to the extent that a certain size of void can be secured in the coking chamber. It was something to say. As can be seen in the prior invention mentioned above, in the case of molded coal for molded coke with low caking properties, the technology has been developed based on the judgment that the molded coals on the furnace wall cannot fuse together. Although pulverized coal, which has caking properties, is charged, the present inventors found that in the process of conducting a carbonization test of briquette coal for briquette coke, the caking properties of briquette coal were significantly reduced if the briquette size exceeded a certain level. They discovered that even when lowered, the molten coal on the furnace wall was sufficiently fused to withstand extrusion. In other words, as shown in Example 1 below,
When the lump coal size is small (less than 30 cm'), the charging coal cr must be 80 or more, but if the lump coal size is 30 cm
It was discovered that if the CI is increased to 113 or more, the lumped coal will be firmly fused together even if the charged coal CI is less than 80. The results of a carbonization experiment of various types of briquette coal in a horizontal chamber type coke oven showed that the degree of fusion between the briquettes was determined from the fused state of the coke at the time of discharge (visual and photographic judgment) to the extent that it could withstand extrusion. The molded coke originality ratio of those judged to be 80% or less was found to be 80% or less. In addition, when the molded coke was fused to the extent that some space remained, the original molded coke ratio was approximately 30%, so the appropriate fusion range was determined to be 30%.
≦molded coke original form ratio≦80. Using this as a reference value, the appropriate blending conditions for each briquette size are determined in FIG. 1. As shown in Figure 1, the fusion characteristics between lump coals during the carbonization process are greatly affected by the size of the lump coals. It is necessary to adjust the force index.

In addition, if the caking property becomes high and the entire over-agglomerated coal softens, melts and fuses to fill the space, the effect of radiant heat transfer will be lost, so it is important to balance this. Furthermore, considering operational safety, it is preferable to use agglomerated coal with a size of 50 cm or more and a charging coal C.
l50-70.

In addition, in order to effectively utilize radiation heat transfer, the larger the coal size, the better, considering that the space will be blocked by powder brought into the coking chamber and powder generated by falling impact during charging. It is. However, as the lump coal size increases, does it fall during charging? It is easily broken due to r11j, and is prone to shrinkage cracking due to thermal strain during the carbonization process.In particular, if there are many cracks in the furnace wall zone that undergoes rapid heating, it will immediately lead to an increase in extrusion resistance, and eventually it may become impossible to extrude. This is a concern, so when carbonizing large lump charcoal for use in castings, etc., take measures to prevent cracking, such as devising the shape of the charcoal as described below, and lowering the flue temperature during carbonization to a slightly lower temperature. It is necessary to take the following steps. If you take such measures,
It is also possible to carbonize large blocks of foundry coke in horizontal chamber coke ovens. Generally, the larger the agglomerated coal is, the more likely it is to cause shrinkage cracking, so as a measure to avoid this, we devised an agglomerated coal shape that minimizes the area of the isothermal zone within the precinct during the carbonization process. In other words, the idea is that the volume of agglomerated coal can be more than doubled by connecting two or more small agglomerated coals that do not easily cause shrinkage cracking, but agglomerated coal is difficult to crack, and there are no voids in the coking chamber. This will also make it easier to secure a good rate. There are no particular regulations regarding the shape of small agglomerated coal, such as masec, pillow radial, or ovoid, but in order to suppress the occurrence of cracks in the precinct during the carbonization process, from the results of Table 's1, it is shown in Figure 2. It is important that the shape ratio of the lump coal satisfies the conditions of 0.75 a≧b and 2a≦C. Regarding the relationship between d and do, there is no particular problem with d'/d-1 or d'/d-1. In addition, in order to secure effective voids in the carbonization chamber, we tried to sieve and remove the powdered coal and charge only the lumps.
It is important to increase the original form of agglomerated coal as much as possible in the carbonization chamber.

[Example] The present invention will be explained based on examples.

Example-1 Table 2 shows the results of a typical carbonization experiment using a Denton horizontal gas-heated coke oven (carbonization chamber dimensions: width 400 x height 1000 x length 120 ha). The temperature is constant at 1250℃, and the temperature in the coal is 9.
After reaching 50°C, the apparatus was drained for 2 hours. Here, we have shown data for briquette coal sizes of 27cm' (rational type), 56cm' (pillow type), and 92cm' (pillow type), but as the briquette size increases, even though the coking force index is almost the same, the original coke shape The rate decreases and the fusion rate increases.

In particular, when the coal briquette size is as small as 27 crtr', it is difficult to fuse the coal blend unless the caking properties of the coal blend are considerably increased. With regard to coke strength, the strength tends to decrease if there is too much fusion or not enough fusion, and in terms of original shape ratio, the appropriate range is likely to be 30≦original ratio≦80. The key is to properly fuse the briquettes together in this manner, and for this purpose it is important to adjust the caking properties of the coal blend according to the size of the briquettes, as shown in FIG. In addition, blend No. and LO are blended with only non-slightly caking coal, but if the caking properties of the blended coal are adjusted to an appropriate range, the briquettes will firmly fuse together and the coke strength will increase. Even coke equivalent to blast furnace coke or higher was obtained, demonstrating that the present invention greatly expands the range of raw material selection compared to the current indoor furnace method.

Example-2 Table 3 shows a horizontal gas-heated coke oven (dimensions of carbonization chamber: width 400 x height 1000 x length 1200 tx quantity)
When the flue temperature is set to 1250°C, the carbonization characteristics of pulverized coal charging and briquette coal charging are approximately 2.5% higher with 100% briquette charging than with pulverized coal charging. 5h
The carbonization time was also shortened. Furthermore, when the carbonization time was the same, the Freeier temperature could be lowered by about 150°C by charging briquette coal.

Table 3 Carbonization characteristics of briquette coal and pulverized coal Example-3 Figure 3 shows an image of the actual process of the present invention. First, raw coal pulverized to a predetermined particle size is recorded with a caking force index of Cl 40 to 80 at a combined particle size of 1. Mix it within the range of , and mix it with So
After adding and kneading a binder such as P, the molded coal is molded into the desired shape using a double roll molding machine 3, and the powdered coal portion is finally removed by a sieve machine 4 just before charging into a coke oven 5. Then, only the lumps are charged into the coke oven 5, and coke is produced in the same manner as in the operation of a normal indoor coke oven. The powdered coal sieved by the sieve m4 immediately before charging into the coke oven 5 is returned to the kneader 2 and recycled.

[Effects of the Invention] The present invention does not require modifying the existing chamber-type coke oven, but simply adds briquette coal manufacturing equipment to produce briquettes of 30 cm or more, and charges the entire amount into the coke oven, thereby creating a briquette inside the coke oven. As a result of the formation of voids of a certain size, radiation and convection heat transfer occur in addition to conduction heat transfer in the carbonization chamber, resulting in shorter carbonization time, lower Freeier temperature, and use of a large amount of non-slightly caking coal. Remarkable effects such as the following can be achieved.

[Brief explanation of drawings]

Figure 1 shows the appropriate caking range of charged coal depending on the size of coal coal, Figure 2 shows the shape of lump coal that is less prone to shrinkage cracking, and Figure 3 shows , is a diagram showing a process image of the present invention. 1... Raw material blending tank, 2... Kneading machine, 3...
Forming machine, 4... Sieving machine, 5... Horizontal chamber type coke oven. Caking index CI [-] Fig.

Claims (1)

[Claims] 1. In a horizontal chamber type coke oven, the caking property of the charged coal is adjusted to a caking power index CI in the range of 40 to 80 according to the size of agglomerated coal, and then a binder is added. A method for producing coke, which comprises making lump coal of 30 cm^3 or more in size, charging the entire amount into a coke oven, and carbonizing it. 2 Lump coal of two or more connected pieces of various shapes, with the thickness of the connected part being 75% or less of the maximum thickness and the longest diameter being at least twice the thickness, is charged into a coke oven and carbonized. A coke manufacturing method characterized by: