EP0087144A1

EP0087144A1 - Method of charging the coke oven chamber with coal

Info

Publication number: EP0087144A1
Application number: EP83101580A
Authority: EP
Inventors: Hisato c/o Yawata Works Okamoto; Yasutaka c/o Yawata Works Shihara; Toshiaki c/o Yawata Works Hodate; Kesao Katsuno
Original assignee: Nippon Steel Corp
Current assignee: Nippon Steel Corp
Priority date: 1982-02-19
Filing date: 1983-02-18
Publication date: 1983-08-31

Abstract

There is disclosed a method of charging the coke oven chamber with coal, which comprises introducing coal into the chamber at an accelerated rate by mechanical means through an charging hole in the top of the chamber, the accelerated rate being so controlled as to ensure that the coal in the chamber has a substantially uniform bulk density along the entire height and width of the chamber.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a method of charging the coke oven chamber with coal.

2. Description of the Prior Art

It is well known that a charging car is usually used to charge the coke oven chamber (hereafter referred to as "chamber") with coal. The charging car usually has four or five hoppers. Each hopper is provided at its bottom with a rotary feeder through which coal is supplied into the chamber.
As the coal is in the form of particles having, for example, a diameter of -3 mm, 87%, and an apparent specific gravity of 1.25, it falls into the chamber by its own weight.at an initial speed of nearly zero under the influence of a rising gas stream. As a natural consequence, coal has a lower density toward the top of the chamber.
An increase in the bulk density of coal in the chamber is essential for reducing the distances of the coal particles during their heating, softening, melting and solidification (coking) to produce good coke having a high structural strength.
Various methods are known for producing coke of greatly improved quality by raising the bulk density of coal in the entire chamber. They, for example, include a method using briquette, a method using preheated coal, and a method using stamped coal. Although all of them have more or less achieved industrial success, they require very expensive equipment and operation.
The method using preheated coal is, for example, disclosed in U.S. Patent No. 3,432,398. Hot coal particles having a low moisture content are introduced into the chamber through a pipeline by a carrier gas. Although this method has a lot of-advantages, it has the disadvantage of being applicable to only preheated coal, and inapplicable to wet coal having a moisture content of 6% or above which is handled by an ordinary charging car. This is due to the fact that a very long pipeline is required for connection between a coal bin and each chamber of a coke oven, and that a carrier gas having a great amount of energy is required for carrying such wet coal through such a pipeline.
A number of methods are known for raising the bulk density of coal selectively in the upper portion of the chamber. One of them is disclosed in U.S. Patent No. 3,515,293, and employs a leveling bar which is vibrated across the peaked coal piles in the coke oven for leveling them. Alternatively in the method using a coal mixture which contains briquette having a high bulk density, it is known to introduce a large quantity of briquette into the upper portion of the chamber. These methods are, however, still unsatisfactory, and can only to a limited extent improve the bulk density of coal in the upper portion of the chamber.

SUMMARY OF THE INVENTION

It is an object of this invention to eliminate the drawbacks of the prior art as hereinabove pointed out, and provide a novel and improved method of charging the chamber with coal which ensures a substantially uniformly controlled bulk density _2-f coal along the entire height and width of the chamber, and an improved average bulk density of coal throughout the chamber by mechanical means for feeding coal at an accelerated rate without using any carrier gas.
This object is attained by a method of charging the chamber with coal, which comprises introducing coal into the chamber at an accelerated rate by mechanical means through an opening in the top of the chamber, the accelerated rate being so controlled as to ensure that the coal in the chamber have a substantially uniform bulk density along the entire height and width of the chamber.
According to this invention, there is, thus, provided a simple and inexpensive method which enables a drastic improvement in the properties of coke, equalization in the quality of coke throughout the chamber, and a greatly improved yield of coke in lump form.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGURE 1 shows the relation between the dropping distance and impinging speed of coal charged in accordance with this invention;
FIGURE 2 shows the relation between impinging speed and bulk density of coal charged in accordance with this invention;
FIGURE 3 shows the comparison between this invention and a conventional method with respect to the bulk density of coal along the height of a chamber;
FIGURE 4 shows the comparison between this invention and the conventional method with respect to the bulk density of coal along the width of the coke oven chamber;
FIGURE 5 is a front elevational view of a charging car;
FIGURE 6 is a side elevational view of the charging car;
FIGURE 7 is a block diagram showing the principal steps of operation of the charging car;
FIGURE 8 is a series of views showing the charging operation according to this invention and the interior of a chamber;
FIGURE 9 shows the conditions for the charging operation in relation to time;
FIGURE 10 is a schematic side elevational view of a friction type coal charger connected to a charging car;
FIGURE 11 is a detailed side elevational view of the friction type coal charging device;
FIGURE 12 is a front elevational view, partly broken away, of the charging device along the line XII-XII of FIGURE 11;
FIGURE 13 is a side elevational view showing a swinging mechanism in the charging device;
FIGURE 14 shows a charging rate according to this invention by way of example;
FIGURE 15 is a set of graphs showing the bulk density of coal in the chamber according to examples of this invention (TABLE 1), the bulk density along the height of the chamber being shown at A, the bulk density along its length at B, and the bulk density along its width at C; and
FIGURE 16 is a set of graphs comparing this invention and the conventional method with respect to the strength of coke produced.

DETAILED DESCRIPTION OF THE INVENTION

FIGURES 1 and 2 illustrate the basic principles of this invention. FIGURE 1 shows the relation between the dropping distance and impinging speed for coal particles having a diameter of -3 mm, 87%, an apparent spcific gravity of 1.25 and a moisture content of 9.0%, and allowed to drop in the air at different initial speeds. The presence of a coal layer at a given height defines the impinging speed, and the energy of impingement contributes to improving the bulk density of the coal layer.
FIGURE 2 shows the relation between the impinging speed and bulk density of coal particles of the same nature as those employed to obtain the relation shown in FIGURE I. It indicates a great improvement of the bulk density by accelerated charging.
FIGURE 3 shows the bulk density of coal in the chamber of a coke oven along the height thereof. At 'a', it shows the bulk density of coal charged by a conventional method, i.e., allowed to drop by its own weight. A gradual reduction in the bulk density of coal is observed toward the top of the chamber. At 'b', FIGURE 3 shows the results of accelerated charging according to this invention, and indicates that coal can be-charged with any desired bulk density if the rate for such accelerated charging is appropriately controlled in accordance with the level of coal in the coke oven chamber.
FIGURE 4 compares this invention and the conventional method with respect to the bulk density of coal in the coke oven chamber along the width thereof. According to this invention, it is possible to achieve a desired bulk density of coal in the chamber if the rate for accelerated charging is appropriately controlled.
FIGURES 5 and 6 schematically show in front and side elevations, respectively, a charging car provided with impeller type coal charging device to carry out the method of this invention. Conventional hoppers 1 have a capacity which is equal to one charge of coal. A coal feeder 2 of, for gxample, the screw type has one end connected to the bottom of each hopper, while its other end is connected to one of the coal charging device. Each coal charging device 3 is appropriately supported at the bottom of the charging car, and has a casing 3a in which a charging mechanism 3b in the form of, for example, a three-stage impeller is provided. The casing 3a is provided at its bottom with an outlet opening not shown.. A driving system 4 for each coal charging device 3 includes a variable-speed motor 4a and a reduction gear 4b connected to the shaft of the impeller. The roof 7 of a chamber has a number of openings, charging holes, 8 through which coal is introduced into the chamber.
FIGURE 7 shows the sequence of the principal steps employed for charging the coke oven chamber with coal by the apparatus as hereinabove described. First, coal is fed into the hoppers (step 1), and the charging car is moved to the chamber to be charged (step 2). The covers for the charging holes are removed (step 3), and coal is introduced into the chamber (step 4).
The following is done for the introduction of coal:

(1) The motor 4a is started after its rotational speed has been adjusted to achieve a desired charging rate;
(2) Coal is introduced into the coke oven chamber; and
(3) The angle at which coal is injected into the chamber is appropriately varied.

If the chamber is charged with a predetermined bulk density of coal, the covers are replaced to close the charging holes (step 5), and the charging car is moved to a standby position or another chamber to be charged (step 6).
FIGURES 8 and 9 show the process by which the chamber is charged with coal. Referring to FIGURE 8(I), coal is introduced vertically into the chamber 9-through the holes 8 at an accelerated rate, while FIGURES 8(II) and 8(III) show the introduction of coal into the dead spaces between every two adjoining holes 8.
The coal charging devices a are first kept in their original position, and their heads are swung to introduce coal into the chamber 9 through the holes 8 as shown in FIGURE 8(1). The areas into which coal scatters are shown by solid lines when the heads of the coal charging devices remain stationary, and by broken lines when those heads are swung. A coal level is shown by a broken line. As more coal is introduced, the level of coal in the chamber 9 rises, and its bulk density increases. The operation shown in FIGURE 8(I) is continued until predetermined level of coal is obtained in the chamber 9. Then, every two adjoining coal charging devices are moved away from each other to introduce coal into a dead or vacant space d as shown in FIGURE 8(II). Improved results are obtained by the impingement of the coal particles injected from every two adjoining coal charging device into the same space. Then, these charging devices are moved toward each other to inject coal into different spaces e as shown in FIGURE 8(III). The charging devices are rotated in the opposite direction in FIGURE 8(III). The directions in which coal is injected in FIGURES 8(II) and 8(III) are shown by broken lines. The charging car is shown at 5, and the roof 7 is provided with a gas offtake 6.
If coal is introduced at an equal rate throughout the charging of the chamber, a higher bulk density of coal is obtained in the upper portion of the chamber, resulting in the production of coke differing in quality between the upper and lower portions of the chamber. Therefore, the rate at which coal is injected is appropriately lowered in accordance with the progress of the charging operation, as shown by way of example in FIGURE 9, in order to achieve a generally high and uniform bulk density of coal throughout the height of the chamber.
Referring now to FIGURE 10, another apparatus for carrying out the method of this invention comprises a friction type charging device 11 connected to a charging car 14. One such coal charging device 11 is provided for each holes 18a in thereof 18 of a coke oven chamber. Referring to FIGURES 11 to 13, the coal charging device 11 is mounted on a base 12, and suspended slidably or rotatably from guide beams 15 on the charging car 14 by supporting members 13 connected to the base 12. Although FIGURES 10 to 13 show the coal charging device 11 which is movable relative to the charging hole 18a, it is also possible to mount it in a fixed position relative to the charging hole.
A shoe plate or wheel is provided on the upper end of each supporting member 13 to connect it with the guide beam 15. It is, however, possible to employ anything else if it enables the movement of the coal charging device 11 between its standby position and the charging hole.
A mechanism 16 for moving the coal charging device 11 may comprise a fluid pressure cylinder, such as a hydraulic cylinder, which is appropriately supported on the charging car 14. It includes a movable rod 17 having one end connected to one of the supporting members 13. Upon operation of the mechanism 16, the coal charging device 11 is movable to or away from the charging hole 18a. The mechanism 16 is not limited to such a cylinder, but may alternatively comprise a rack and pinion combination, or any other electrical, hydraulic or pneumatic driving unit.
A belt driving motor 19 is mounted on a base plate 10 supported on the base 12, and has an output shaft 51 connected by a coupling 52 and a bearing 53 to a driving pulley 54, as shown in FIGURES 11 and 12. Another driving pulley 55 is connected to the output shaft 51 by a known gear train. The pulleys 54 and 55 are rotatable in mutually opposite directions.
A pair of driven pulleys 56 and 57 are disposed; below the driving pulleys 54 and 55, and supported swingably on arms 59 pinned to a frame 58 for the coal charging device 11. An automatic torque control device 20, which may comprise a spring or like resilient member, is disposed between the frame 58 and the arms 59. A belt 21 for carrying coal extends around the pulleys 54 and 56, and another belt 22 extending around the pulleys 55 and 57 faces the belt 21. The endless belts 21 and 22 define therebetween a path for coal having an inlet 23 at its upper end and an outlet 24 at its lower end. The outlet 24 is smaller than the inlet 23. The belts 21 and 22 may, for example, be formed from hard heat-resistant rubber. Their surfaces facing the coal path are preferably formed with appropriately arranged projections 25 having a shape suitable for engaging and forwarding coal particles. A casing 26 is open at its upper and lower ends, and surrounds the belts 21 and 22. The belts 21 and 22 are driven by the driving pulleys 54 and 55 in the directions shown by arrows in FIGURE 12 to forward coal frictionally so that the coal particles introduced through the inlet 23 may be discharged through the outlet 24 into the coke oven. Both sides of the coal path between the belts 21 and 22 are closed by side plates not shown. Each side plate lies perpendicularly to the belts, and comprises a pair of members supported in the vicinity of the belt edges, and overlapping each other slidably relative to each other.
The base plate 10 is provided at its bottom with supporting members 27 by which it is supported rotatably about a shaft 29 carried by bearings 28 on the base 12. The base plate 10 has an extension 30. An auxiliary shoot 31 has a lower end disposed in the inlet 23 between the belts 21 and 22, and an upper end supported by the car 14 so that it may be communicated with the hopper 14a.
A motor 32 is mounted on the base 12 for swinging the belts 21 and 22, and has an output shaft on which a chain wheel 33 is mounted. The base 12 has an upright frame 12a on which a shaft 35 is supported by bearings 34. A chain wheel 36 is carried on the shaft 35, and a chain 37 extends around the chain wheels 33 and 36 to define a power transmission for the motor 32.
A disk plate 38 is loosely fitted about the shaft 35 and supported by a supporting frame 12b. The disk plate is detachably engaged with the peripheral edge of a rotary disk 45 by a spring or like resilient member 39. A guide box 40 is keyed or otherwise connected to the shaft 35. The guide box 40 has an elongated hole 41, and a top 43 is fitted slidably in the hole 41. The top 43 is perpendicular to the hole 41, and has a shaft portion 42 projecting outwardly from the guide box 40. The top 43 has a threaded through hole in which a screw shaft 44 lying along the elongated hole 41 is threadedly received through the guide box 40. The rotary disk 45 is connected to the lower end of the screw shaft 44. The disk plate 38 is disengageable from the rotary disk 45 when desired.
A swing plate 46 is connected directly or indirectly to one end of the base plate 10, and has a straight groove 47 in the surface facing the guide box 40. The shaft 42 of the top 43 has a free end slidably received in the groove 47. The groove 47 is preferably in parallel to the elongated hole 41 of the guide box 40 as long as the charging device 11 is in its normal charging position in which the belts 21 and 22 have a vertical line of symmetry. The top 43 is connected to the screw shaft 44 so that its shaft portion 42 may have a horizontal axis aligned with that of the shaft 35. A slidable duct 48 has one end defining an opening which surrounds the charging hole 18a, while the other end of the duct 48 is connected expansibly to a stationary duct 49.
The operation of the apparatus as hereinabove described is based on the results of the research efforts made by the inventors of this invention which will hereinafter be set forth:

(1) The relation between the drop distance and impinging speed of coal allowed to drop in the air at a certain initial speed indicates that the presence of a coal layer at a given height defines the impinging speed, and that the energy of such impingement contributes to improving the bulk density of coal in the coke oven; and
(2) The relation between the impinging speed and bulk density of coal indicates a great improvement of the bulk density by accelerated charging. They have also succeeded in obtaining any desired bulk density of coal along the height and length of the coke oven chamber by controlling the charging rate appropriately in accordance with a rise in the level of coal in the chamber.

FIGURE 14 shows by way of example a charging rate which makes it possible to maintain a uniform bulk density of coal in the coke oven chamber along its entire height, while minimizing the variation in the bulk density of coal along the width of the chamber. Some correction may be required for the bulk density distribution along the height of the chamber, depending on the coke oven, since the temperature distribution along the height of the oven may have a certain effect on the bulk density. Accordingly, a control system contains a plurality of interchangeable patterns, including coal properties, such as particle size, apparent specific gravity and moisture content, mixing ratio, coke oven temperature distribution, charging rate, and angle of belt swinging. The operator of the_charging car may select an optimum combination of such factors to achieve a desired bulk density of coal.
In the operation of the apparatus shown in FIGURE 10, the charging car 14 is moved to a position above the roof 18 of the chamber to be charged, and the cover 18b is removed from the charging hole 18a. The hydraulic cylinder 16 is actuated to move the coal charging device 11 from its standby position to an operative position above the charging hole 18a along the guide beams 15. The charging device 11 is stopped at its operative position by the function of a positioning sensor not shown. As a result, the inlet 23 of the coal path between the belts 21 and 22 is situated below the lower end of the auxiliary shoot 31, and its outlet 24 is so positioned as to establish communication with the chamber through the charging hole 18a. All the operating contro including an control for the movement of the coal charging device 11 to the charging hole 18a, are given simultaneously from the operating .room for the charging car.
Then, the motor 19 is placed in operation to drive the belts 21 and 22, and after the belts have reached a predetermined speed of rotation, a rotary feeder 14b provided at the bottom of the hopper 14a is started to feed coal from the hopper 14a onto the fast rotating belts-21 and 22 which-in turn inject coal into the coke oven chamber. The automatic torque control device 20 functions if coal particles having a size greater than the prescribed value are fed from the hopper. The rate for charging the chamber 60 is automatically selected and controlled based on a preset control pattern in accordance with the signals or directions given to the motor 19 provided with speed varying means.
The belts 21 and 22 are swung to control the bulk density of coal along the length of the coke oven chamber, while controlling the bulk density of coal along its height by adjusting the charging rate in accordance with a predetermined pattern. The motor 32 is placed in operation, and its rotation is transmitted through the chain 37 to the shaft 35 to rotate it. As the guide box 40 is integrally connected to the shaft 35, the guide box 40, the top 43 and the screw shaft 44 are rotated with the shaft 35. The-rotation of the guide box 40 causes the rotation about its own center of the rotary disk 45 against the peripheral edge of which the disk plate 38 is pressed. With the rotation of the rotary disk 45, the screw shaft 44, which is integrally connected to the rotary disk 45, is rotated about its axis, and the top 43 threadedly connected with the screw shaft 44 is moved upwardly in FIGURE 13 along the elongated hole 41 of the guide box 40. As the shaft 35 is in rotation, the projecting shaft portion 42 of the top 43 makes eccentric rotation. As a result, the swing plate 46 is swung in accordance with the eccentric rotation of the shaft portion 42 received in the straight groove 47 of the swing plate 46. Accordingly, the base plate 10 is swung about the shaft 29 along the length of the coke oven, or in a plane parallel to the plane. in which the belts 21 and 22 lie. Any other means than the arrangement shown in FIGURES 11 to 13 can be used for swinging the belts. For example, it is possible to employ an appropriate means for driving the shaft 29 directly to swing the base plate 10.
As the operation of the motor 32 is further continued, the eccentric motion of the top 43 is gradually increased with a resultant increase in the swinging angle or amplitude of the driving system including the belts 21 and 22 with the lapse of time. The maximum amplitude depends on the inside diameter of the roof opening 18a of the chamber 60. It is, therefore, necessary to select the charging rate and the various factors of the swinging mechanism in such a manner that the maximum amplitude may be obtained after a predetermined period of swinging. It is possible to employ any other angle of swinging for charging coal if the engagement between the disk plate 38 and the rotary disk 45 is removed before the eccentric motion of the top 43 reaches its maximum level.
The dust rising from coal during the charging operation is collected into the stationary duct 49 through the dust collecting hood 48a of the slidable duct 48.
The rotary feeder 14b and the motor 19 are automatically stopped when the level of coal in the coke oven chamber 60 has reached its uppermost level, or more precisely, a position slightly below its uppermost level, and the motor 32 is rotated in the opposite direction to reduce the swinging motion until the apparatus is eventually restored to its original position. The hydraulic cylinder 16 is moved in the opposite direction to retract the charging device 11 from the charging hole 18a. The coal charging device 11 is automatically stopped in its standby position by a standby position sensor, not shown, and the hydraulic cylinder 16 is placed out of operation.
The inventors have made a careful study of the effects of high-speed charging on the wall of the chamber, and the problem of dust rising from coal, and found that the method of this invention is entirely free from any such problem, and of great value in practical application. More specifically, they have found that the coal particles introduced into the chamber scatter within only a limited angle of, say, 6°, and cannot have any adverse; effect on the chamber wall. They have also found that as the slidable duct collects dust, the dust rising-from ordinary wet coal having a moisture content of, say, 9% does not have any adverse effect on the working environment.
According to this invention, it is possible to use a coal mixture containing 10 to 40% by weight of briquette, in addition to ordinary coal for coking. According to this invention, the rate at which coal is introduced into the chamber depends on the desired bulk density of coal in the chamber, but is preferably in the range of 25 to 60 m/sec. initially, and finally 18 to 20 m/sec.
The invention will now be described with reference to several examples thereof. The charging tests were conducted under the conditions shown in TABLE 1.
FIGURE 14 shows by way of example variations in the coal charging rate according to the control pattern shown in TABLE 1.
FIGURE 15 shows the bulk density of coal obtained in EXAMPLES I and II of this invention and the comparative example which are shown in TABLE 1. The bulk density of coal along the height of the chamber is shown in FIGURE 15(A), the bulk density along its length in FIGURE.15(B), and the bulk density along its width in FIGURE 15(C). As is obvious from FIGURE 15, the examples of this invention show an average bulk density of 0.9 t/m throughout the chamber which is an improvement of about 30% over the value of 0.7 t/m³ according to the conventional method. This invention enables a substantially uniform bulk density of coal along the height of the chamber by virtue of an appropriate control of the charging rate, while the conventional method brings about a great difference between the upper and lower portions of the chamber, the upper portion having a higher bulk density of coal. According ` to this invention, the swinging of the coal charging device enables a uniform bulk density of coal along the length of the chamber, while the conventional method brings about a higher bulk density of coal immediately below the charging hole than in a region between every two adjoining charging holes. As regards the bulk density of coal along the width of the chamber, this invention enables a higher density in the center than in the areas close to the chamber walls, while the conventional method brings about a substantially uniform density along the entire width of the chamber. This is a desirable factor for the production of uniform quality, since it is well known that coke is higher in strength close to the walls of the chamber than in the center thereof.
TABLES 2 and 3 and FIGURE 16 compare the strength of the coke produced by the conventional method which comprises allowing coal to drop into the chamber by its own weight, and by the method of this invention. The tests were conducted under the same conditions as those shown in TABLE 1.
As is obvious from TABLES 2 and 3, the coke produced according to the method of this invention is greatly superior both in cold strength (
) and in hot strength (CSR) to the product of the conventional method. The results shown in FIGURE 16 confirm the uniformity of coke quality along the height, length and width of the chamber, while the conventional method brings about a great difference in coke quality along the height, length and width of the chamber.
The method of this invention is successfully applicable for charging the coke oven chamber with not only preheated coal, but also ordinary wet coal, since coal is introduced at an accelerated rate into the chamber through the coal charging device positioned in the vicinity of the charging hole of the chamber.

Claims

1. A method of charging the coke oven chamber with coal, comprising introducing coal into the chamber by a mechanical means at an accelerated rate through a charging hole in the roof of said chamber, said rate being so controlled as to achieve a substantial uniformity in the bulk density of coal in said chamber along the entire height and width of said chamber.

2. A method as set forth in Claim 1, wherein said rate is controlled in accordance with a predetermined control pattern.

3. A method as set forth in Claim 1, wherein coal is introduced at an angle which is variable along the length of said chamber.

4. A method as set forth in Claim 1, wherein said mechanical means is swung within a predetermined amplitude along the length of said chamber about a fixed axis or an axis which is movable along the length of said chamber.

5. A method as set forth in Claim 1, wherein said rate is initially in the range of 25 to 60 m/sec., and finally in the range of 18 to 20 m/sec.

6. A method as set forth in Claim 1, wherein said coal contains 10 to 40% by weight of briquette.

7. A method as set forth in Claim 1, wherein said means comprises an impeller type coal charging device.

8. A method as set forth in Claim 1, wherein said means comprises a friction type coal charging device.