JPS63122784A - Production of highly elastic coal block - Google Patents

Abstract

PURPOSE:To improve modulus of elasticity of coal block and to make it possible to carbonize coal block in a chamber oven, by charging a mold with pulverized coal, compression molding the pulverized coal, releasing pressure from the coal block and further compressing the coal block to produce permanent set. CONSTITUTION:Pulverized coal is fed to a mold, compression molded, further molded to give coal block, from which pressure is released. The coal block is further compressed and permanent set is produced in the coal block. A highly elastic block which is fed to a chamber oven and carbonized into coke and has a little smaller dimension than that of the chamber oven. Consequently, self-stability of coal block and stability of handling are improved and cost of installation and power expense are reduced.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a method for manufacturing a highly elastic coal block, and in particular, the present invention relates to a method for producing a highly elastic coal block, and in particular, a coal block that is slightly smaller than the indoor furnace used for charging into an indoor furnace and carbonizing it to produce coke. A technique for providing dimensional coal blocks, applied in the field of coke industry.

The following explanation of this specification is about a technique for obtaining a suitable coal block by focusing on the deformation characteristics of the molded "coal block" rather than the elastic deformation behavior of the powdered coal itself.

(Prior Art) Generally, when pulverized coal is pressurized, it is compacted with only moisture and becomes a green compact formed into an arbitrary shape. The powdered coal particles in this green compact are in contact with each other through moisture, and the degree of this contact is usually stronger in the direction of the compaction axis compared to the direction perpendicular to the compaction axis. (shown in Figure 2).

Several techniques have already been proposed in which such powder is compression-molded and subjected to a chamber furnace as a molded body.
The compression molded coal manufacturing technology disclosed in Japanese Patent No. 9-12710 has a drawback that when a horizontal press molding machine is used, the degree of contact between powdered coal particles in the height direction is weaker than in the lateral direction.

Furthermore, the method disclosed in Japanese Patent Application Laid-open No. 53-25602 is a production technique in which a stamper is dropped in the vertical direction to compact it, but the degree of contact between the powdered coal particles in the horizontal direction is less than that in the vertical direction. It is possible that it will become weaker.

Of course, in the case of each of the above-mentioned conventional techniques as well, as the molding pressure increases, the compressive strength improves. This is thought to be because powdered coal particles having various shapes fit into each other and their contact area is expanded. Even in this case, although the pulverized coal particles fit together smoothly in the direction of the forming axis, the degree of fitting is weak in the direction perpendicular to the forming axis because the consolidation force is small. For this reason, the compressive strength becomes weak in the direction perpendicular to the forming axis, and there is a problem in that plastic deformation occurs when compressed.

On the other hand, when the compacting pressure is low, there is a problem in that the degree of contact between the powdered coal particles is weak even in the direction of the compacting axis, causing plastic deformation.

(Problem that the invention attempts to solve) Elastic modulus is a typical indicator of mechanical properties.

A material with a large elastic modulus means a large strain stress. Therefore, when this function is applied to a coal block, it is thought that when the elastic modulus is large, it indicates that distortion is less likely to occur, which improves safety when handling the coal block. Handling here refers to the self-supporting of coal blocks, horizontal carrying, and charging into coke ovens. For example, the fact that a coal block can stably stand on its own without buckling indicates that it has good handling properties. Regarding buckling in such handling property, the longitudinal elastic modulus E is involved as shown in the following equation.

β=F (E) l: Buckling height m), E: Longitudinal elastic modulus < kg
/ cm2) When this E is large, the buckling height β becomes high.

This means that if the coal blocks are of the same height, the one with a larger E can stably stand on its own. In particular, when the height direction is perpendicular to the molding axis, there is a problem that the self-standing is unstable because E is low.

In this regard, in the case of the technique disclosed in JP-A-53-25602, the height H) and thickness (W
) has been described as having a ratio (H/W) of 14 to 16 times, preferably 15 times, and there was a problem in that the H-height of conventional tamped cakes was limited to 16 times or less.

Even when this coal block is handled horizontally, it is affected by the acceleration of conveyance and vertical vibration caused by the height of the rail, so if the elastic modulus of the coal block is low, there is a high risk of deformation and collapse. Also, when charging a coal block into a coke oven, it is moved on a shoe, so there is no need to push the coal block directly.
Conditions within the furnace, such as deposited carbon, may come into contact with the top of the coal block. In such a case, if the elastic modulus is low, there is a risk of deformation and collapse due to the impact of the deposited carbon.

That is, an object of the present invention is to improve the elastic modulus of a coal block, solve the above-mentioned problem (plastic deformation after formation), and realize industrialization of indoor furnace carbonization of a coal block.

(Means for solving the problem) Powdered coal particles have various shapes such as polygonal, round, and flat shapes, and have different particle sizes. Therefore, when the powdered coal particles are charged into a mold and compressed, the powdered coal particles are influenced by their respective shapes during the molding process, and it is extremely difficult to obtain ideal close packing. In particular, considering that a part of the compacting pressure in the mold is consumed by friction between the powdered coal particles and the wall surface of the mold, there is a limit to the compacting pressure that is industrially profitable. Therefore, since large molding pressures cannot be used, coal blocks exhibiting perfect elasticity cannot be molded, and it has been found that all coal blocks undergo plastic deformation to varying degrees.

Furthermore, if the formed coal block is removed from the mold and pressurized while maintaining the state in which each powdered coal particle constituting the coal block can freely move slightly without being constrained by the mold, a small pressurizing force can be applied. It was found that an improvement in the elastic modulus can be expected.

In short, the present invention provides a highly elastic coal block characterized in that the coal block is compression-molded by charging powdered coal into a mold, the pressure is released, and then the coal block is further compressed to cause permanent deformation. Adopt manufacturing methods as a means to solve problems.

(Function) Generally, when a coal block made of powdered coal is compressed, permanent strain remains as shown in Figure 3. Experimental block molded in the horizontal direction (358'
O' ) mm is compressed in the vertical direction (perpendicular to the forming axis) with a compressive force of 3 tons, leaving a permanent strain with a longitudinal displacement of 4 mm. In addition, when an experimental block that was molded by compression from the lateral direction is held upright and compressed from the same direction as the molding axis,
Permanent strain of several mm was observed in the compression axis direction.

As described above, even if the pulverized coal particles themselves remain elastic, a coal block formed by compression molding a large number of pulverized coal particles deforms and develops permanent deformation.

This is because the powdered coal particles are not only spherical but also irregularly shaped polyhedrons, and have an uneven shape, so when forming progresses, the particles fit together, but on the other hand, they are restrained by friction between the powdered coal particles. Since the particles are restrained by the wall surface of the mold, movement of the particles is suppressed, and a sufficient degree of fitting and contact cannot be obtained. Then, when the molding is continued, the powdered coal particles contact each other and are pressed together in an overlapping state. As a result, the particles themselves in turn become strained within their elastic limits. At this stage, when the molding pressure is returned to zero,
The coal block springs back the press head.

Therefore, in order to remove the constraint from the mold wall, we tried compressing the molded coal block after removing it from the mold, but the particles in the part that was in contact with the wall also moved slightly, causing permanent deformation. It was found that the contact condition was improved to provide a good fit. In this case, the pressurizing force required for compression is effective because there is no frictional force on the wall surface, so a small pressurizing force can be effective.

In the direction of the forming axis, the powdered coal particles behave as described above, but since the pressing force is small in the direction perpendicular to the forming axis, the degree of contact and fit of the particles is weak. In this case, in order to improve the degree of contact and fit of particles in the direction perpendicular to the molding axis, the coal block is compressed by moving the side wall from the direction perpendicular to the molding axis while it is still housed in the mold. becomes effective. However, mold molding still has the disadvantage that a portion of the compressive force is consumed by friction on the mold wall surface.

Therefore, in the present invention, when the coal block that has been compression molded is removed from the mold and compressed to create permanent deformation, the fitting state and degree of contact of the powdered coal particles is better than that of omnidirectional molding while stored in the mold. The properties of the coal blocks have also been improved, and the coal blocks now exhibit the same elasticity that pulverized coal particles have. (Since the elastic modulus is used in mechanical engineering as a parameter to express elasticity, the coal block is also expressed as the elastic modulus.) As explained above, the coal block formed in the mold is in a state where permanent deformation is likely to occur. As it is, the elastic modulus is still small. However, when the present invention compresses the coal block, which is prone to permanent deformation, outside the mold and causes permanent deformation, the elastic modulus is significantly improved (
become larger).

For example, the height of a coal block for a chamber furnace is 6 to 7 m.

Since the bottom of this coal block is compressed from the top, the fit and contact degree of the powdered coal particles is improved to some extent, resulting in a large elastic modulus, but the upper part has no permanent strain, so the elastic modulus is small. .

Even in the direction of the molding axis where the degree of contact between the powdered coal particles is strong and the fit is good, the coal block has the property of leaving a permanent strain when compressed, and by leaving this permanent strain, the elastic modulus of the upper part is greatly improved as mentioned above. can.

That is, considering the buckling theory, the upper part becomes difficult to stand on its own statically and is likely to buckle. When exposed to external force in this state, it easily deforms, causing permanent deformation and becoming bent, losing its own weight balance and easily buckling.

In this regard, by improving the elastic modulus of the coal block according to the present invention to increase the elastic modulus, the above-mentioned buckling can be prevented and a coal block that can withstand practical operations can be manufactured.

The manufacturing process according to the present invention will be explained based on FIG.
The process consists of charging powdered coal into a mold, compression molding it, and taking the resulting coal block out of the mold and compressing it. As a compression method, a press can be used. A rubber press or the like is preferable to protect the coal block. Further, it is preferable to adopt a mechanism in which the coal block discharged from the molding machine can be compressed by pressing down from the top of the coal block with a taper liner, and the height and inclination angle of the taper liner can be adjusted.

As for the method of pre-compressing and leaving a permanent set, there are two methods: one is to repeatedly apply compression force, and the other is to apply compression force to hold the material.

Furthermore, there is also a compression method as shown in FIG.

The coal blocks (forming block 3, recompression block 4) that come out of the horizontal molding machine 5 are moved in the axial direction of the press 6 of the molding machine,
That is, it consists of a ceiling press 1 that compresses from above and below with respect to the horizontal extrusion direction, and a side wall press 2 that compresses from the width direction perpendicular to the horizontal extrusion direction.First, the block compressed by the vertical compression press is compressed in the width direction by the side wall press. is compressed again.

Further, when compressing in the vertical direction by the ceiling press 1, the side wall may be a movable side wall mold, and may be a movable side wall whose width is adjusted in advance to match the amount of lateral strain generated.

(Example) Example 1 The coal blend shown in Table 1 was molded using a horizontal molding machine to form a coal block (3
58' x 1000L x 100O+mm) was manufactured.

First Molding Conditions Next, the coal block was compression molded in a direction perpendicular to the molding axis using a vertical press. The relationship between longitudinal displacement and compressive force at this time is shown in Figure 3. In order to obtain a coal block slightly larger than the commercial furnace height of 7 m, a compression force of 3 tons (0.8
When compressed at 4 kgf/cm2), the longitudinal displacement was 6 mm. The longitudinal elastic modulus E at this time is 140 kg/am2
It was calculated that When the compressive force was decreased in this state, the vertical displacement decreased as shown by curve 2 in the figure, and when the compressive force was zero, a permanent strain of 4 mm remained.

Next, when the same compressive force of 3 tons was applied to the above coal block, the coal block behaved as shown by the curve (■) in the figure.

The longitudinal displacement at this time was about 2.5 mm, and the longitudinal elastic modulus E was improved to 330 kg/cm2. Compared to curve ■, E is improved by 2.3 times. As the compressive force was decreased, the vertical displacement decreased as shown by curve (2), but the permanent deformation was very small.

Figure 4 shows the results of the third compression with a compression force of 3 tons. The longitudinal elastic modulus E was further improved to 360 kg/cm2. In this case, the coal block behaved almost like an elastic body. By pre-compressing the coal block that had been formed in this way outside the mold to leave a permanent strain, the modulus of longitudinal elasticity E was significantly improved.

In this case, compression is performed without being restrained by the mold wall, so the compression force is 3 tons (0.84 kgf 70
m”), and the longitudinal elastic modulus E could be effectively improved.

Example 2 The powdered coal shown in Table 1 was molded using a horizontal molding machine at a pressure of 51 kgf/cm.
It was molded in 2. Coal block taken out from the molding machine (3
58"
61 kgf/cm2). The longitudinal displacement in the first compression was 5.9 mm, and the longitudinal elastic modulus E was 100.
It was calculated as kg/cm2. When the compression force is returned to zero, it becomes 3.5.
A permanent strain of mm remained.

As a result of the second compression with a compression force of 2.2 tons, the vertical displacement was approximately 2.4 mm, and E at this time was 250 kg/cm.
Improved to 2. When the compression force was returned to zero, the permanent strain was small.

(Effect of the invention) According to the present invention, the following effects can be expected.

(1) The self-supporting stability and handling stability of the coal block are improved. In other words, the coal block, which was previously said to be impossible, has a height (H) and a thickness (III).
) Even if the ratio (H/W) exceeds 16, self-sustaining stability can be ensured. Therefore, according to the present invention, a large coal block can be carbonized in an existing large coke oven, a large amount of low-grade slightly coking coal can be used, and productivity can be improved by about 15%.

(2) Since the coal block is compressed without being restrained by the mold wall surface, permanent deformation can be left with a small compression force. Therefore, there is an advantage that equipment costs and power costs are reduced.

[Brief explanation of the drawing]

Figure 1 is a process diagram of the present invention. Figure 2 is a graph showing the relationship between compressive strength in the direction of the molding axis and the direction perpendicular to the molding axis. Figure 3 shows the presence of permanent strain that occurs when compressed. Figure 4 is a graph showing the relationship between longitudinal displacement and compression force when compression molding is performed on a coal block that has been compressed in advance to leave a permanent strain. Figure 5 is a graph showing one implementation of the compression method. It is a sectional view of a horizontal compression molding machine showing an example. 1...Ceiling press 3.4...Coal block 2
... Side wall press 5 ... Horizontal molding machine 6 ... Press No. 3 of the molding machine [Z! Figure 4

Claims (1)

[Claims] 1. A method for producing a highly elastic coal block, which comprises charging powdered coal into a mold and compression-molding the coal block, releasing the pressure, and then further compressing the coal block to cause permanent deformation in the coal block.