JP2008264657A - Fluidized bed drying and classifying apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent condensation of moisture in gas used for drying coal on the inner wall part of a drying and classifying chamber and to efficiently produce coarse-grained coal charged into a coke oven. <P>SOLUTION: A fluidized bed drying and classifying apparatus where a fluidized bed 16 is formed over a dispersion plate 15 in the drying and classifying chamber 14 by jetting gas, introduced from a main introduction pipe 18 into a gas chamber 26, through the dispersion plate 15 to dry coal and, at the same time, to classify powdered coal in coal generated by the drying, comprises a branch pipe 20 branched from the main introduction pipe 18 to introduce branched gas into a gas space 14a, into which gas used for drying coal rises up, in the drying and classifying chamber 14, and a collision plate 35 guiding the branched gas, introduced from the branch pipe 20, to the inner wall part of the drying and classifying chamber 14. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a fluidized bed drying and classifying device for classifying coarse and pulverized coal in dried coal by transferring and drying while fluidizing coal by a fluidized bed formed by gas ejected from a dispersion plate. About.

  In a normal blast furnace coke manufacturing process, from the viewpoint of improving coke strength by increasing the charging bulk density and improving productivity by shortening the carbonization time, coal containing about 8-12% moisture is dried and about 6% or less. After reducing the amount of water until, it is charged into a coke oven.

  However, if the moisture content in the coal is reduced due to the drying of the coal, the amount of fine powder of about 0.5 mm or less that is likely to generate dust increases, which causes the working environment to deteriorate. For this reason, after drying the coal or separating the pulverized coal of about 0.5 mm or less generated by drying at the same time as drying the coal from the coarse coal by classification, adding a binder to the pulverized coal, kneading, After the grain or the molding, the coarse coal is mixed and charged into the coke oven.

  Conventionally, as a drying classifier that combines the functions of a coal dryer and a classifier, high temperature gas is blown upward through a plurality of outlets of the dispersion plate, and the coal particles are stirred and dried on the dispersion plate. 2. Description of the Related Art There is known a fluidized bed drying classifier that forms a fluidized bed that moves from the inlet side to the coal discharge port side, and blows up the pulverized coal generated during drying and discharges it from above to separate it from the system.

  In this fluidized bed drying classifier, the gas that has passed through the dispersion plate has a gas temperature of about 300 to 400 ° C. at the time of blowing, and the water in the coal is evaporated by heat exchange with the coal. In the drying zone up to, the gas temperature decreases to around 80 ° C. in the course of increasing.

  For this reason, especially in the drying zone from the coal inlet to the center, moisture in the gas is condensed on the inner wall of the upper space of the drying classification chamber, and the wall is corroded by dissolution of the corrosive components in the coal into the moisture. There is a risk.

Therefore, a method is known in which a branch pipe obtained by branching a part of the main introduction pipe for high-temperature gas is connected to the upper part of the drying classification chamber, and high-temperature gas is blown into the upper space in the drying classification chamber via the branch pipe. (For example, refer to Patent Document 1).
JP-A-10-253251

  However, in the above-described configuration, the high-temperature gas flowing in through the branch pipe flows toward the center of the drying classification chamber, so that the inner wall portion of the upper space where corrosion due to condensation is a problem cannot be sufficiently heated. For this reason, moisture in the high temperature gas may condense on the inner wall of the upper space and cause corrosion.

  In addition, when high-temperature gas flows into the drying classification chamber via the branch pipe, the gas flow near the inner wall is disturbed, and the coarse coal blown up from the fluidized bed to the upper space is entrained, and is placed in the top (ceiling) of the drying classification chamber. High-temperature gas containing coarse coal is discharged together with pulverized coal from the connected exhaust duct, and the classification efficiency of pulverized coal is reduced. When the mixing ratio of coarse coal in the recovered pulverized coal increases, the amount of caking material to be used increases when granulating, and the yield of forming coal tends to decrease when forming.

  Therefore, the present invention prevents the gas containing a large amount of moisture from contacting with the inner wall of the upper space of the drying classification chamber from contact and condensation, and prevents the mixing of coarse coal in the exhaust gas, It aims at providing the fluidized-bed dry classification apparatus which can maintain the classification efficiency of pulverized coal favorably.

In order to solve the above problems, the present invention forms a fluidized bed on the dispersion plate in the dry classification chamber by ejecting the gas introduced from the main introduction pipe into the gas chamber through the dispersion plate, and dries the coal. And a classification device for classifying pulverized coal in coal generated by drying,
A branch pipe that branches from the main introduction pipe and introduces a branch gas into the gas space in the drying classification chamber in which the gas used for drying the coal rises;
A collision plate that forms a moving space for moving the branch gas is provided between an inner wall portion of the drying classification chamber, and the branch gas is allowed to collide with the collision plate.

  Here, it is preferable that the collision plate is inclined so as to approach the inner wall portion upward.

  Moreover, it is preferable that the gas discharge port of the branch pipe is formed in a region corresponding to the outside in the horizontal direction of the dispersion plate.

  Furthermore, the drying classification chamber is formed from a drying zone used for drying the coal, and a classification zone for removing pulverized coal from coal dried in the drying zone, and the guide plate is disposed only in the drying zone. Good.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a schematic cross-sectional view showing the overall configuration of the dry classification apparatus of the present invention, 11 is a wet coal hopper for storing raw coal before dry classification, and 12 is a cutting apparatus for taking out a predetermined amount of raw coal. , 13 is an inlet, and a predetermined amount of raw coal extracted from the wet coal hopper 11 by the cutting device 12 is charged into the dry classification chamber 14 through the inlet 13.

  The inner wall portion of the drying classifying chamber 14 includes a slanted wall portion 41 in which a horizontal dimension (XY plane direction) gradually decreases in a taper shape downward, and a vertical wall portion 42 extending upward from the upper end of the slanted wall portion 41. It is composed of

  An inlet 13 is provided at one end in the horizontal direction (Y-axis direction) of the inclined wall portion 41 of the dry classification chamber 14, and a dry coal discharge port 31 is provided at the other end. The dry coal discharge port 31 has a dry classification. A discharge device 32 for discharging the subsequent coal by a predetermined amount is attached.

  A dispersion plate 15 is disposed in the drying classification chamber 14 at a position corresponding to the lower end of the inclined wall portion 41, and a number of gas ejection holes are spaced apart from each other at a predetermined interval. And is drilled.

  The fluidized bed 16 can be formed on the dispersion plate by ejecting a hot gas in a gas chamber, which will be described later, into the dry classification chamber 14 through the gas ejection holes of the dispersion plate 15. The drying classification chamber 14 is divided into two in the Y-axis direction (coal flow direction) by a partition wall 25, and the upstream side of the partition wall 25, that is, the charging port 13 side is defined as a drying zone 14 a. The downstream side, that is, the dry coal discharge port 31 side is defined as a classification zone 14b.

  Exhaust ducts 19a and 19b for discharging pulverized coal particles together with exhaust gas are provided on the ceilings of the drying zone 14a and the classification zone 14b. Cyclone dust collectors 24a and 24b are attached to the exhaust ducts 19a and 19b via pipes, respectively, and separate pulverized coal particles and exhaust gas.

  The pulverized coal particles separated by the dust collectors 24a and 24b are appropriately discharged by the pulverized powder discharging devices 27a and 27b. The drying zone 14a means a region mainly intended for drying coal, and the drying zone 14a has a higher moisture content in the coal than the classification zone 14b, so the amount of pulverized coal in the exhaust gas is relatively small. However, the pulverized coal is recovered by the dust collector 24a.

  A gas chamber 26 is provided below the dispersion plate 15, and in this embodiment, the gas chamber 26 is divided into six parts. The three chambers on the charging port 13 side are heating gas chambers 26a for forming a fluidized bed for drying, and the three chambers on the dry coal discharge port 31 side are heating gas chambers for forming a fluidized bed for classification. 26b.

A heating gas having a pressure and a flow rate sufficient to form a fluidized bed is introduced from the hot air generator 23 into the heating gas chambers 26 a and 26 b via a hot air duct (main introduction pipe) 18. In the illustrated apparatus, a hot air flow rate adjusting valve 17 is attached to each of the hot air ducts 18 connected to the heating gas chambers 26a and 26b, and the flow rate of the heating gas is set to an arbitrary value by the hot air flow rate adjusting valve 17, and The heating gas chambers 26a and 26b can be independently adjusted. A bypass duct 20 is provided in the vicinity of the duct end portion of the hot air duct 18.

  Next, the bypass duct (branch pipe) 20 will be described in detail with reference to FIG. Here, FIG. 2 is a plan view of the drying zone 14a in the drying classification chamber 14 shown in FIG.

  As shown in FIG. 1, a bypass duct 20 is provided in the vicinity of the duct end portion of the hot air duct 18, and this bypass duct 20 is further connected to first to third bypass branch ducts 20a to 20c as shown in FIG. Branched.

  The terminal end of the first bypass branch duct 20 a is formed at the end in the Y-axis direction of the vertical wall portion 42 of the drying zone 14 a of the drying classification chamber 14, and the branch gas flowing in via the bypass duct 20 is dried. It is introduced into the zone 14a.

  The terminal end of the second bypass branch duct 20b is formed at one end in the X-axis direction of the vertical wall portion 42 of the drying zone 14a of the drying classification chamber 14, and the branch gas flowing in via the bypass duct 20 is dried. It is introduced into the zone 14a.

  The terminal end of the third bypass branch duct 20c is formed at the other end in the X-axis direction of the vertical wall portion 42 of the drying zone 14a, and the branch gas flowing through the bypass duct 20 is allowed to enter the drying zone 14a. It is introduced.

  As shown in FIG. 1, the bypass duct 20 is provided with a bypass flow rate adjustment valve 22. By operating the bypass flow rate adjustment valve 22, the end in the Y-axis direction in the drying zone 14 a and the bypass duct 20 are provided. The flow rate of the branch gas flowing into both ends of the X-axis direction can be adjusted.

  First to third collision plates 35a to 35c are provided in the drying zone 14a, and these first to third collision plates 35a to 35c are respectively first to third bypass branch ducts 20a. The second and third collision plates 35b to 35c are arranged on the vertical wall portion 42 so as to cover the region of the coal flow direction (Y-axis direction) in the drying zone 14a. Has been.

  By arranging the first to third collision plates 35a to 35c in this manner, the first to third bypasses are provided between the first to third collision plates 35a to 35c and the inner wall portion of the drying zone 14a. A moving space for moving the gas discharged from the outlets of the branch ducts 20a to 20c along the inner wall portion can be formed.

  In this moving space, high-temperature gas flows between the inner wall of the vertical wall portion 42 located at the Y-axis direction end and the X-axis direction both ends of the drying classification chamber 14 and the first to third collision plates 35a to 35c. Because it moves with a predetermined residence time along each inner wall, each inner wall and its vicinity are sufficiently heated, suppressing moisture condensation on each inner wall, and by dissolving corrosion components in coal into moisture Corrosion can be prevented.

  Further, since the high-temperature gas that has flowed into the dry classification chamber 14 from the bypass branch ducts 20a to 20c collides with the first to third collision plates 35a to 35c, the gas flow velocity is reduced. As a result of entraining the blown-up coarse coal and preventing it from being discharged from the discharge duct, the classification efficiency of the pulverized coal can be improved.

  In the upper space of the drying zone 14a, the moisture content in the gas atmosphere is higher than that in the classification zone 14b, the temperature drop of the gas is large, and corrosion due to moisture condensation on the inner wall portion is likely to occur. For this reason, by arranging the collision plate 35 only in the upper space of the drying zone 14a, the cost can be reduced as compared with the case where the collision plate 35 is arranged in the entire drying zone 14a and classification zone 14b.

  Each of the first to third collision plates 35a to 35c is inclined so as to gradually approach the inner wall portion of the drying zone 14a toward the upper side, and is supported by a support member (not shown).

  As a material constituting the first to third collision plates 35a to 35c, stainless steel having excellent corrosion resistance can be exemplified.

  Next, the operation method of the drying classification apparatus of a present Example is demonstrated. When the drying classifier is in operation, the heated gas at about 400 ° C. from the hot air generator 23 is adjusted to a predetermined flow rate by the hot air flow rate control valve 17 and supplied into the heating gas chambers 26a and 26b. At this time, a part of the heating gas is also introduced into the drying zone 14a through the branched bypass duct 20.

  On the other hand, undried unclassified raw coal in the wet coal hopper 11 is supplied into the dry classification chamber 14 through the inlet 13 by a predetermined amount by the cutting device 12. Therefore, the raw coal is first dried from the coal inlet 13 side while being stirred on the dispersion plate 15 by the heated gas blown into the drying zone 14a in the drying classification chamber 14 through the plurality of gas ejection holes of the dispersion plate 15. The fluidized bed 16 moving to the discharge port 31 side is formed.

  Here, the raw material coal is mainly dried by the heating gas, the raw material coal is dried, the temperature is lowered by heat exchange, and the heating gas containing a large amount of water rises in the drying zone 14a and is generated by partial drying. The pulverized coal is discharged from an exhaust duct 19a provided on the ceiling. The coarse coal particles in the raw coal move to the dry coal discharge port 31 while being stirred in the fluidized bed 16 formed on the dispersion plate 15.

  Here, the heating gas introduced into the drying classification chamber 14 through the heating gas chamber 26a and the dispersion plate 15 exchanges heat with the raw material coal when passing through the fluidized bed 16 on the dispersion plate, As the moisture in the coal evaporates, the temperature of the heated gas decreases.

  In the present embodiment, the branch gas flowing in via the first to third bypass branch ducts 20a to 20c is collided with the collision plates 35a to 35c and guided to the inner wall portion of the drying zone 14a.

  That is, a hot gas moving space is formed between the inner wall of the vertical wall portion 42 at the Y-axis direction end and the X-axis direction both ends of the drying classification chamber, and the first to third collision plates 35a to 35c. Since the hot gas moves along each inner wall part with a predetermined residence time, each inner wall part and its vicinity are sufficiently heated to suppress moisture condensation on each inner wall part, and into the moisture of corrosive components in coal. It is possible to prevent corrosion due to dissolution.

  Further, as illustrated in FIG. 3, a region near the wall portions 41 and 42 indicated by hatching (hereinafter referred to as a flow velocity reduction region A) formed outside the planar view (X-axis direction view) of the dispersion plate 15 is as follows. Since the flow rate of the heated gas that rises is slower than in other regions, condensation tends to occur on the inner wall due to the temperature drop.

  Thus, even in a type of dry classification device in which condensation is likely to occur, moisture condensation on the inner wall portion can be suppressed, and corrosion due to corrosive components dissolved in moisture can be reliably prevented.

  Further, since the collision plate 35 is inclined so as to gradually approach the inner wall portion of the drying zone 14a upward, the branch gas can be reliably guided to the vertical wall portion 42.

  Moreover, since the high temperature gas which flowed into the dry classification chamber 14 from the bypass branch ducts 20a to 20c is decelerated by colliding with the first to third collision plates 35a to 35c, it is blown up from the fluidized bed 16 to the upper space. It is possible to prevent the coarse coal from being caught and discharged from the discharge duct 19. As a result, mixing of coarse coal in the exhaust gas can be prevented, and the classification efficiency of pulverized coal can be improved.

  Coarse granular coal heated and dried in the drying zone 14a moves to the discharge port side on the dispersion plate 15 while exhibiting a fluidized bed, and sequentially moves to the classification zone 14b. In the classification zone 14b, as in the drying zone 14a, the raw material coal forms a fluidized bed that moves to the coal discharge port 31 while being stirred on the dispersion plate 15 by the heated gas ejected from the dispersion plate 15.

  In the classification zone 14b, the water content in the coal is lower than that in the drying zone 14a, and the pulverized coal adhering to the coarse coal or the pulverized coal adhering to each other is easily dissociated. The pulverized coal particles dissociated as a result of the decrease in moisture rises together with the heated gas, and is discharged from the exhaust duct 19b. The coarse coal particles are dried while being fluidized on the dispersion plate 15, and discharged through the coal discharge port 31. A predetermined amount is discharged by the device 32. As a result, the coal is dried to a predetermined moisture, and pulverized coal is classified from coarse coal in the dried coal.

  Since pulverized coal mainly classified by coarse coal and having a particle size of about 0.5 mm or less is likely to generate dust, a caking agent such as tar is added and kneaded with a kneader. Granulate with a granulator or form charcoal with a molding machine. The pulverized coal subjected to the dust generation prevention treatment is mixed with coarse coal and charged into a coke oven, and used as a raw material for coke.

(Other examples)
In the above-described embodiment, the drying classification chamber 14 is divided into the drying zone 14a and the classification zone 14b. However, the present invention also applies to a drying classification apparatus that uses the entire area of the drying classification chamber 14 to dry coal. Can be applied. In this case, the second and third collision plates 35 may be disposed in substantially the entire Y-axis direction (coal flow direction) of the drying classification chamber 14, or may be disposed only in the upstream region where condensation is likely to occur. May be.

  Further, although the collision plate 35 has a flat plate shape, it may have any shape as long as the branch gas can be guided to the wall portions 41 and 42. For example, a bent plate obtained by bending and deforming the flat collision plate 35 into a “he” shape can be used.

It is a schematic sectional drawing which shows the whole structure of a drying classification apparatus. It is a top view of the drying zone of a drying classification chamber. It is a schematic diagram which shows the flow-velocity distribution of a drying zone.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Coal hopper 12 Cutting device 13 Loading port 14 Drying classification chamber 14a Drying zone 14b Classification zone 15 Dispersion plate 16 Fluidized bed 17 Hot air flow rate control valve 18 Hot air duct 19 Exhaust duct 20 Bypass ducts 20a-c 1st-3rd Bypass branch duct 22 Bypass flow control valve 23 Hot air generator 24 Dust collector
25 Partition Wall 26 Gas Chamber 27 Fine Powder Discharge Device 31 Dry Coal Discharge Port 35 Collision Plate 41 Slanted Wall Part 42 Vertical Wall Part

Claims (4)

The gas introduced into the gas chamber from the main introduction pipe is ejected through the dispersion plate to form a fluidized bed on the dispersion plate in the drying classification chamber, and the coal is dried and simultaneously the pulverized coal in the coal generated by drying is removed. A fluidized bed drying and classifying device for classifying,
A branch pipe that branches from the main introduction pipe and introduces a branch gas into the gas space in the drying classification chamber in which the gas used for drying the coal rises;
A collision plate that forms a moving space for moving the branch gas between the inner wall portion of the drying classification chamber,
A fluidized bed drying and classifying apparatus characterized by causing the branch gas to collide with the collision plate.   The fluidized bed drying / classifying apparatus according to claim 1, wherein the collision plate is inclined so as to approach the inner wall portion upward.   The fluidized bed drying and classifying apparatus according to claim 2, wherein a gas discharge port of the branch pipe is formed in a region corresponding to an outer side in the horizontal direction of the dispersion plate. The drying classification chamber is formed of a drying zone used for drying the coal, and a classification zone for removing pulverized coal from coal dried in the drying zone,
The fluidized bed drying and classifying apparatus according to any one of claims 1 to 3, wherein the collision plate is disposed only in the drying zone.

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