JP6741393B2 - Fluidized bed apparatus and method for dry classification of coal using the same - Google Patents

Description

TECHNICAL FIELD The present invention relates to a fluidized bed apparatus and a method for dry classification of coal using the same.

In the technology of producing coke, it is common practice to dry and classify coal before carbonization (that is, before charging into a coke oven). Patent documents 1 and 2 disclose a fluidized bed device as a device for drying and classifying coal. The fluidized bed apparatus generally includes a fluidized bed main body into which coal is introduced, and a plenum chamber. The fluidized bed body includes a perforated plate on which a plurality of nozzles are formed, and coal is placed on the perforated plate. The plenum chamber is provided below the perforated plate. Hot air for fluidizing coal (that is, forming a fluidized bed) is introduced into the plenum chamber. The hot air blows through the nozzle of the perforated plate into the fluidized bed body to fluidize the coal (that is, to form a fluidized bed). The hot air that has passed through the fluidized bed, that is, the exhaust gas, passes through the freeboard section and is discharged from the exhaust gas discharge port.

In the fluidized bed apparatus disclosed in Patent Documents 1 and 2, such a fluidized bed main body is divided into a drying chamber and a classification chamber by partitions (partition walls). Hot air is introduced into each of the drying chamber and the classification chamber. In the drying chamber, coal is dried by forming the fluidized bed with hot air. The hot air that fluidized the coal passes through the drying chamber freeboard portion as the drying chamber exhaust gas, and is discharged from the drying chamber exhaust gas outlet. In addition, coal having a classification point or less (for example, pulverized coal having a particle size of 0.3 mm or less) may be discharged from the drying chamber exhaust gas discharge port.

In the technology disclosed in Patent Documents 1 and 2, coal contained in the exhaust gas of the drying chamber is collected by the drying chamber collector. In the technique disclosed in Patent Document 1, the recovered coal is put into the classification chamber. In the technique disclosed in Patent Document 2, agglomerated coal is produced by agglomerating the recovered coal.

In the classification chamber, the coal dried in the drying chamber is made into a fluidized bed by hot air. The hot air that has fluidized the coal passes through the classification chamber freeboard section, and is discharged from the classification chamber exhaust gas outlet as classification chamber exhaust gas. On the other hand, in the fluidized bed, the pseudo-particle-shaped coal is scrubbed by hot air and decomposed into a plurality of particles (for example, coarse coal having a particle size larger than 0.5 mm and pulverized coal having a particle size of 0.3 mm or smaller). Further, coal having a classification point or less (for example, pulverized coal having a particle size of 0.3 mm or less) is blown into the classification chamber freeboard section by hot air. The coal blown into the classification room freeboard section is discharged from the classification room exhaust gas outlet together with the classification room exhaust gas. On the other hand, the coal remaining in the fluidized bed (that is, the coal having a size larger than the classification point, for example, coarse-grained coal having a particle size larger than 0.5 mm) is discharged from the coal outlet. Thereby, the coal is classified.

In the techniques disclosed in Patent Documents 1 and 2, coal contained in the exhaust gas of the classification chamber is collected by the classification chamber collector. In the technique disclosed in Patent Document 1, the recovered coal is preheated in a gas flow tower and then agglomerated. In the technique disclosed in Patent Document 2, the recovered coal is put into a drying chamber collector.

JP-A-2003-277764 JP, 2010-243023, A JP, 2007-23170, A Japanese Patent No. 4102426 Japanese Patent Laid-Open No. 10-246573

By the way, as disclosed in Patent Documents 3 and 4, in order to improve the strength of the agglomerated coal, it is necessary to control the temperature of the coal that is a raw material of the agglomerated coal to 120 to 170°C. However, the technologies disclosed in Patent Documents 1 and 2 cannot perform such control.

Specifically, in the technique disclosed in Patent Document 1, as described above, the coal contained in the exhaust gas of the drying chamber is recovered and the recovered coal is supplied to the classification chamber. Then, in the classification chamber, the coal in the classification chamber (that is, the coal dried in the drying chamber and the coal recovered from the exhaust gas from the drying chamber) is classified and heated to 300°C. Therefore, according to this technique, the temperature of coal contained in the exhaust gas of the classification chamber is about 300°C. The coal contained in the exhaust gas from the classification chamber also includes the coal recovered from the exhaust gas from the drying chamber. Therefore, according to this technique, the coal recovered from the exhaust gas from the drying chamber can be heated to about 300°C.

Here, the reason why the coal recovered from the exhaust gas from the drying chamber is heated to about 300° C. is as follows. That is, in the technique disclosed in Patent Document 1, the coal recovered from the exhaust gas from the classification chamber is heated in the gas flow tower and then charged into the agglomerated coal manufacturing apparatus. Here, since the coal recovered from the exhaust gas from the drying chamber contains a large amount of water, when this coal is heated in a gas flow tower, thermal cracking of the coal occurs, and the pulverized coal generated by this causes various troubles. Cause. Therefore, in the technique disclosed in Patent Document 1, water is removed from the coal recovered from the exhaust gas from the classification chamber, and then the coal is introduced into the airflow tower. Therefore, with this technique, it was not possible to control the temperature of coal, which is a raw material for agglomerated coal, to 120 to 170°C.

In the technique disclosed in Patent Document 2, as described above, the coal recovered from the exhaust gas from the classification chamber is charged into the drying chamber collector. Therefore, in addition to the coal recovered from the exhaust gas of the classification chamber, the coal recovered from the exhaust gas of the drying chamber is input to the dryer trap. Then, the coal recovered from the exhaust gas from the classification chamber is cooled by the coal recovered from the exhaust gas from the drying chamber. As a result, the temperature of coal, which is a raw material for agglomerated coal, can be lowered. However, with this technique, the temperature of the coal was too low. Specifically, the coal, which is a raw material for agglomerated coal, has dropped to 110° C. or lower. Therefore, even with the technique disclosed in Patent Document 2, it was not possible to control the temperature of coal, which is a raw material for agglomerated coal, to 120 to 170°C.

On the other hand, Patent Document 5 discloses a technique similar to the technique disclosed in Patent Documents 1 and 2. In the technique disclosed in Patent Document 5, the fluidized bed apparatus is divided into a drying chamber and a cooling chamber. Then, the coal recovered from the exhaust gas from the drying chamber is put into the cooling chamber, and the coal contained in the exhaust gas from the cooling chamber is recovered. In this technique, coal contained in the exhaust gas of the cooling chamber can be a raw material for agglomerated coal. However, since this coal is cooled in the cooling chamber, it becomes lower than 120°C. Therefore, even with the technique disclosed in Patent Document 5, it was not possible to control the temperature of coal, which is a raw material for agglomerated coal, to 120 to 170°C.

Therefore, the present invention has been made in view of the above problems, and an object of the present invention is to control the temperature of coal, which is a raw material of agglomerated coal, to 120 to 170° C. Another object of the present invention is to provide an improved fluidized bed apparatus and a method for drying and classifying coal using the same.

In order to solve the above-mentioned problems, according to an aspect of the present invention, a coal supplied from a coking coal supply unit is formed into a fluidized bed by hot air for drying, and a drying chamber for drying coal and a drying chamber for drying. By forming the fluidized bed with the classified coal into a fluidized bed with hot air for classification, a classification chamber for classifying the coal dried in the drying chamber, a partition wall separating the drying chamber and the classification chamber, and the exhaust gas discharged from the drying chamber are included. A low temperature coal supply unit for charging coal into the classification chamber from above the fluidized bed in the classification chamber, and controlling the temperature of the coal contained in the exhaust gas discharged from the classification chamber to 120 to 159 °C. , A fluidized bed apparatus is provided.
Here, when the temperature of the hot air for drying becomes maximum, the temperature of the exhaust gas discharged from the drying chamber may be 90 to 100°C.

Further, the drying chamber may dry the coal supplied from the raw coal supply section until the water content becomes 2 to 5% by mass.

Further, the height from the connection port between the low temperature coal supply unit and the classification chamber to the bottom surface of the fluidized bed in the classification chamber may be three times or more the stationary height of the fluidized bed in the classification chamber.

Further, the connection port between the low temperature coal supply unit and the classification chamber may be arranged at a position different from the position directly above the coal discharge port of the classification chamber.

Further, the drying chamber has a drying chamber freeboard portion formed above the fluidized bed in the drying chamber, the classification chamber has a classification chamber freeboard portion formed above the fluidized bed in the classification chamber, The average flow velocity of the exhaust gas flowing in the drying chamber freeboard portion may be smaller than the average flow velocity of the exhaust gas flowing in the classification chamber freeboard portion.

Further, the height of the dry room freeboard portion may be 0.6 times or more of the transport release height TDH represented by the following formula (1).

In the formula (1), W ₀ is the width of the fluidized bed in the drying chamber, and U ₀ is the average flow velocity of the gas flowing in the drying chamber freeboard section.

Further, the plurality of nozzles provided on the perforated plate forming the bottom surfaces of the drying chamber and the classification chamber may extend in the vertical direction.

According to another aspect of the present invention, there is provided a method for dry classification of coal, which comprises drying and classifying coal using the above fluidized bed apparatus.

As described above, according to the present invention, coal contained in the exhaust gas discharged from the drying chamber is charged into the classification chamber from above the fluidized bed in the classification chamber. This coal is at a lower temperature than the coal blown from the fluidized bed of the classification chamber and contains a large amount of water. Therefore, the temperature of the coal contained in the exhaust gas discharged from the classification chamber, that is, the coal that is the raw material of the agglomerated coal, can be lowered, and can be controlled to 120 to 170°C.

It is an explanatory view showing composition of a coal pretreatment system concerning an embodiment of the present invention. It is explanatory drawing which shows the cross-sectional shape of a classification room freeboard part. It is explanatory drawing which shows the correspondence of the height from a fluidized bed bottom, and dust generation intensity. It is a graph which shows an example of temperature distribution in a fluidized bed apparatus. It is a graph which shows the correspondence of hot air temperature and coal temperature (fine coal temperature and coarse grain temperature).

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the present specification and the drawings, components having substantially the same functional configuration are designated by the same reference numerals, and duplicate description will be omitted.

<1. Overall configuration of coal pretreatment system>
First, an overall configuration of a coal pretreatment system according to an embodiment of the present invention will be described with reference to FIG. FIG. 1 is an explanatory diagram showing the overall configuration of a coal pretreatment system according to an embodiment of the present invention.

The coal pretreatment system according to the present embodiment is a facility for pretreatment of the coal charged into the coke oven 50. In this pretreatment, the dry distillation time in the coke oven 50 is shortened by drying and heating the raw coal in advance, and the pulverized coal in the raw coal is classified and agglomerated to prevent dust generation of the pulverized coal. It is for suppressing the carry-over phenomenon.

Specifically, as shown in FIG. 1, the coal pretreatment system includes a fluidized bed apparatus 100, a hot air generator 11, a low temperature coal collector 13, a high temperature coal collector 15, and a low temperature coal supply. The unit 71, a kneading machine 35, and an agglomerating machine 37 are mainly provided.

(Fluid bed apparatus 100)
The fluidized bed apparatus 100 performs drying and classification of the coal X1 by forming the coking coal (coal X1) supplied from the coking coal hopper (coking coal supply unit) 165 into a fluidized bed with hot air. The fluidized bed apparatus 100 includes a fluidized bed body 120 and a plenum chamber 130. The fluidized bed body 120 has a substantially rectangular shape in a plan view and is divided into a drying chamber 121 and a classification chamber 122 by a partition wall 111. A space, that is, a dry coal discharge port 112 is formed at the lower end of the partition wall 111. The plenum chamber 130 is a region for introducing hot air into the fluidized bed body 120, and is divided into plenum chambers 131 and 132 by the partition wall 135. The partitions 111 and 135 are provided in the same vertical plane. Hot air for drying, that is, hot air for drying 131a is introduced into the plenum chamber 131, and hot air for classification, that is, hot air for classification 132a is introduced into the plenum chamber 132.

In the drying chamber 121, the coal X1 is dried by using the hot air for drying 131a to convert the coal X1 into the fluidized bed X21. From the drying chamber 121, the drying chamber exhaust gas 181a and the coal X4 are discharged. The temperature of the drying chamber exhaust gas 181a is 90 to 100° C. when the temperature of the drying hot air 131a supplied to the drying chamber 121 is maximum. That is, in this embodiment, the position of the partition wall 111 is determined so that the above conditions are satisfied.

In the classification chamber 122, the coal X1 is classified into the fluidized bed X22 by the hot air 132a. From the classification chamber 122, the classification chamber exhaust gas 182a and the coal X5 are discharged. The coals X4 and X5 are coals having a classification point or less, for example, pulverized coal having a particle size of 0.3 mm or less. However, the coal X4 has a lower temperature than the coal X5 and contains a large amount of water. In this embodiment, the coal X4 is recovered from the exhaust gas 181a of the drying chamber and supplied into the freeboard section 212 of the classification chamber 122. Thereby, the temperature of the coal X5 can be lowered. Specifically, the temperature of the coal X5 can be controlled to 120 to 170°C.

Further, the coal X3 classified by the fluidized bed apparatus (that is, coal larger than the classification point, for example, coarse-grained coal with a particle size larger than 0.5 mm) is discharged from the coal discharge port 170 of the fluidized bed apparatus 100, and the coke oven. It is transported to 50. On the other hand, the coal X5 classified by the fluidized bed apparatus 100 is collected by the high temperature coal collector 15 and conveyed to the kneader 35. The kneader 35 kneads the coal X5 and the binder to produce a kneaded product. The agglomeration machine 37 produces agglomerated coal by agglomerating the kneaded material. Here, in the present embodiment, the temperature of the coal X5 is controlled to 120 to 170° C., so that agglomerated coal with high strength can be produced. As a result, coke with high strength can be produced. The agglomerated coal is charged into the coke oven 50 together with the coal X3. The ratio of the coals X3 and X5 is, for example, about X3:X5=70% by mass:30% by mass. The detailed configuration of the fluidized bed apparatus 100 will be described later.

(Hot air generator 11)
The fluidized bed hot air generating furnace 11 is a device that generates hot air to be supplied to the fluidized bed apparatus 100 described above, and generates combustion exhaust gas (that is, hot air) that is heated by burning fuel gas and air, and this is set to a predetermined value. The temperature and the flow rate are controlled to be supplied to the fluidized bed apparatus 100. Here, examples of the fuel gas include gas fuels such as liquefied natural gas (LNG) and liquefied petroleum gas (LPG), coke oven gas (COG), blast furnace gas (BFG), converter gas (LDG), and the like. By-product gas generated in an iron mill or a mixed gas thereof can be used.

The hot air generating furnace 11 is connected to the lower part of the plenum chamber 130 of the fluidized bed apparatus 100 via the hot air supply pipe 311. In the example shown in FIG. 2, the plenum chamber 130 is divided into two chambers, plenum chambers 131 and 132, and the hot air supply pipe 311 is branched and connected to each of the plenum chambers 131 to 132. Further, the hot air supply pipe 311 branched and connected to each of the plenum chambers 131 to 132 is provided with two hot air control valves 313a and 313b corresponding to each of the plenum chambers 131 to 132. Thereby, the flow rates of the drying hot air 131a and 132a supplied to the plenum chambers 131 to 132 can be independently controlled.

Further, the hot air supply pipe 311 connected to the plenum chamber 130 is branched, and the hot air generation furnace 11 is connected to the upper part of the freeboard portion 211 of the drying chamber 121 via the branched hot air supply pipe 311. You can Further, the hot air supply pipe 311 connected to the upper portion of the freeboard portion 211 may be provided with a hot air control valve 315. By adjusting the hot air control valve 315, the amount of hot air supplied to the freeboard section 211 can be controlled. Thereby, the temperature of the coal X4 discharged from the drying chamber 211 can be controlled to an arbitrary temperature. Of course, it is not necessary to introduce hot air into the freeboard unit 211.

Further, the temperature of the hot air generated in the hot air generating furnace 11 is preferably 500° C. or lower, and more preferably 400° C. or lower in order to prevent alteration of the coal supplied to the fluidized bed apparatus 100. Further, from the viewpoint of improving the strength of the coke, the coal X3 is preferably preheated to 200 to 350° C. and then charged into the coke oven 50. From such a viewpoint, it is preferable that the temperature of the hot air generated in the hot air generating furnace 11 is approximately 200 to 350° C. and is as high as possible.

Further, the hot air generated in the hot air generating furnace 11 contains air as described above, but the oxygen concentration in the hot air is from the viewpoint of preventing ignition of the coal supplied to the fluidized bed apparatus 100. 6 volume% or less is preferable.

Further, if the fuel gas is burned with only air in the hot air generating furnace 11 so as to satisfy the above-mentioned residual oxygen amount, the temperature of the combustion exhaust gas generated becomes too high. From such a viewpoint, the hot air generating furnace 11 uses the exhaust gas generated from the fluidized bed apparatus 100.

(Low temperature coal collector 13, high temperature coal collector 15)
The low temperature coal collector 13 is connected to the drying chamber exhaust gas outlet 181 via the drying chamber exhaust pipe 317. The high temperature coal collector 15 is connected to the classification chamber exhaust gas outlet 182 via the classification chamber exhaust pipe 319.

With such a configuration, the drying chamber exhaust gas 181a and the coal X4 are introduced into the low temperature coal collector 13 from the drying chamber 211 through the drying chamber exhaust pipe 317. The low-temperature coal collector 13 collects (collects) the coal X4 from the drying chamber exhaust gas 181a and discharges the drying chamber exhaust gas 181a after coal recovery. The recovered coal X4 is supplied to the freeboard section 212 of the classification chamber 22 through the low temperature coal supply section 71.

Further, in the high temperature coal collector 15, the classification chamber exhaust gas 182a and the coal X5 are introduced from the classification chamber 212 through the classification chamber exhaust pipe 319. The high-temperature coal collector 15 collects the coal X5 from the classification chamber exhaust gas 182a and discharges the classification chamber exhaust gas 182a after the coal recovery. The recovered coal X5 is conveyed to the kneader 35.

Examples of the low-temperature coal collector 13 and the high-temperature coal collector 15 are cyclones that separate and collect fine powders by using centrifugal force (for example, multi-clones, multi-cyclones) and gas containing fine powders with a filter cloth. It is possible to use a bag filter or the like that separates and collects fine powder by filtering with. Here, since pulverized coal that is difficult to collect in a cyclone may circulate, a bag filter is more preferable as the low-temperature coal collector 13 and the high-temperature coal collector 15 according to the present embodiment. .. However, when a bag filter is used, the temperature of the exhaust gas discharged from the fluidized bed apparatus 100 is taken into consideration, and a filter made of a material having an appropriate heat resistant temperature is selected.

(Low temperature coal supply unit 71)
In this embodiment, the low temperature coal collector 13 and the freeboard part 212 of the classification chamber 122 are connected by the low temperature coal supply part 71. The low temperature coal supply unit 71 supplies the coal X4 recovered by the low temperature coal collector 13 to the freeboard unit 212 of the classification chamber 122. As described above, the temperature of the coal X4 is lower than the temperature of the coal X5 and contains a large amount of water. Therefore, the temperature of the coal X5 in the freeboard part 212 can be lowered by supplying the coal X4 to the freeboard part 212 of the classification chamber 122. In the present embodiment, since the temperature of the exhaust gas 181a of the drying chamber is set to 90 to 100° C. and the coal X4 is charged into the freeboard portion 212 of the classification chamber 122, the temperature of the coal X5 is controlled to 120 to 170° C. You can

If the low-temperature coal supply unit 71 does not exist, the temperature of the coal X5 will be about 200°C.

Further, even when coal X4 discharged from the drying chamber exhaust gas outlet 181 and drying chamber exhaust gas 181a and coal X5 discharged from the classification chamber exhaust gas outlet 182 and classification chamber exhaust gas 182a are mixed, the temperature of coal X5 is 120 to It can be 170°C. However, the temperature of the mixed exhaust gas rises higher than that of the drying chamber exhaust gas 181a, so the thermal efficiency is significantly impaired. Therefore, this method is not preferable from the viewpoint of thermal efficiency. On the other hand, in the present embodiment, since the low temperature coal supply unit 71 supplies only the coal X4 to the freeboard unit 212, each exhaust gas is treated independently. Therefore, the thermal efficiency is hardly reduced.

(Exhaust gas circulation)
The drying chamber exhaust gas 181a discharged from the low temperature coal collector 13 after the coal X4 is collected by the low temperature coal collector 13 passes through the low temperature exhaust gas exhaust pipe 321 and a part of the high temperature coal collector 15 flows. Along with the discharged exhaust gas 182a of the classification chamber, it is returned to the hot air generating furnace 11, and the rest is exhausted from the exhaust tower 19 to the outside of the system by being attracted by the exhaust tower induction blower 17. The amount of exhaust gas discharged from the desorption tower 19 to the outside of the system is adjusted by the low temperature exhaust gas control valve 323.

Further, the classification chamber exhaust gas 182a discharged from the high temperature coal collector 15 passes through the high temperature exhaust gas exhaust pipe 325 and is mixed with a part of the drying chamber exhaust gas 181a discharged from the low temperature coal collector 13. Then, the mixed exhaust gas (hereinafter, also referred to as “fluidized bed circulation gas”) is attracted by the fluidized bed circulation gas blower 21 and returned to the hot air generating furnace 11. In addition, a part of the drying chamber exhaust gas 181a discharged from the low temperature coal collector 13 does not necessarily have to be mixed with the classification chamber exhaust gas 182a in the high temperature exhaust gas exhaust pipe 325 as described above. It may be mixed with the classification chamber exhaust gas 182a in the pipe 319. In this case, the temperature of the fluidized bed circulation gas returned to the hot air generating furnace 11 after mixing hardly changes and the thermal efficiency does not change, but the gas temperature entering the high temperature coal collector 15 can be lowered.

The amount of the classification chamber exhaust gas 182a discharged from the high temperature coal collector 15 may be adjusted by the high temperature exhaust gas control valve 327 in relation to the classification hot air 132a. The amount of the fluidized bed circulation gas returned to the hot air generating furnace 11 by the fluidized bed circulation gas blower 21 depends on the desired amount of the hot air generated in the hot air generating furnace 11 and the desired oxygen concentration, as described above. The circulation gas flow rate control valve 329 is used for adjustment. An amount of the fluidized bed circulation gas regulated by the fluidized bed circulation gas flow rate control valve 329 is supplied to the hot air generation furnace 11 by the fluidized bed circulation gas supply pipe 331 connecting the hot air generation furnace 11 and the fluidized bed circulation gas blower 21. To be done.

(Kneader 35)
The kneader 35 kneads the coal X5 conveyed from the high-temperature coal collector 15 with a binder for agglomeration to produce a kneaded product, and supplies this kneaded product to the agglomerator 37. More specifically, the coal X5 conveyed from the high temperature coal collector 15 is once loaded into a hopper (not shown). Coal X5 is cut out from the hopper by a rotary valve (not shown) or the like into the kneading machine 35 in a predetermined cutting amount. The pulverized coal cut out by the kneading machine 35 is kneaded in the kneading machine 35 with a binder for agglomeration added separately.

Here, as the binder for agglomeration, for example, generally, tar and a residue obtained by simple distillation of tar to remove low-temperature volatile components (for example, soft pitch, which is a coal tar distillate having a softening point of 70° C. or less, , A petroleum pitch having a low softening point of 70° C. or lower, which is liquid at room temperature, etc. are used. This is because the tar discharged as a result of dry distillation in the coke oven 50 can be reused and the quality of the produced coke is improved. It should be noted that medium pitches (softening point 70 to 85° C.) and hard pitches (softening point 85° C. or higher) having a high softening point are solid at room temperature and are not suitable for handling.

(Aggregator 37)
The agglomerator 37 mainly includes, for example, a pushing screw and two rolls. The pushing screw pushes the kneaded material between the two rolls. The two rolls are arranged with a predetermined roll gap, one roll is fixed, and the other roll is rotated by being pressed with a constant pressure by hydraulic pressure, thereby rotating from the outlet side of the roll. Agglomerated kneaded material, that is, agglomerated coal, is released. The agglomerated coal is conveyed to the coke oven 50 together with the coal X3.
<2. Structure of fluidized bed equipment>
Next, the configuration of the fluidized bed apparatus 100 will be described in detail with reference to FIG. As shown in FIG. 1, the fluidized bed apparatus 100 includes a fluidized bed main body 120, a plenum chamber 130, and a coking coal hopper 165. The fluidized bed apparatus 100 is a so-called dry classifier, and performs drying and classification of the coal X1 using the fluidized beds X21 and X22.

The hopper 165 stores the coal X1. The hopper 165 is connected to the fluidized bed body 120 and introduces the coal X1 into the fluidized bed body 120.

The coal X1 contains, for example, about 10 mass% of water with respect to the total mass. Further, the coal X1 includes, for example, coarse coal having a particle size larger than 0.5 mm and pulverized coal having a particle size of 0.3 mm or less. The particle size in the present embodiment is measured using, for example, a sieve having different mesh sizes. For example, a sieve having an opening of 0.3 mm is prepared, and the coal to be measured is passed through this sieve. The coal remaining on the sieve has a particle size of more than 0.3 mm, and the powdered ore dropped from the sieve has a particle size of 0.3 mm or less.

The fluidized bed body 120 has a substantially rectangular shape in a plan view and is divided into a drying chamber 121 and a classification chamber 122 by a partition wall 111. A space, that is, a dry coal discharge port 112 is formed at the lower end of the partition wall 111. The plenum chamber 130 is a region for introducing a fluidizing gas into the fluidized bed body 120, and is divided by the partition wall 135 into plenum chambers 131 and 132. The partitions 111 and 135 are provided in the same vertical plane.

The drying chamber 121 dries the coal X1 by forming (that is, fluidizing) the coal X1 into a fluidized bed X21 by hot air 131a for drying described below. The coal X1 is preferably dried in the drying chamber 121 until the water content becomes 2 to 5% by mass. By drying the coal X1 in the drying chamber 121 until the water content becomes 2 to 5% by mass, the temperature of the coal X5 can be more reliably set to 120 to 170°C, and the classification accuracy of the coal X1 is increased. be able to.

That is, by drying the coal X1 in the drying chamber 121 until the water content becomes 2 to 5% by mass, it is possible to remove the water content that binds the coarse coal and the pulverized coal in the pseudo particles. This makes it possible to more reliably decompose the pseudo particles into coarse coal and pulverized coal. As a result, the pulverized coal in the fluidized bed X21 can be more surely blown into the freeboard portion 211, so that the coal X4 can be increased. Since the coal X4 becomes a cooling material that cools the coal X5, it is possible to more reliably cool the coal X5 by increasing the amount of the coal X4. Further, since the pulverized coal in the fluidized bed X21 is reduced, the classification accuracy is improved.

The drying chamber 121 includes a fluidized bed portion 201, a freeboard portion 211, a perforated plate 141, a raw material inlet 160, and a drying chamber exhaust gas outlet 181.

The fluidized bed portion 201 is an area where the fluidized bed X21 of the coal X1 is formed, and the bottom surface of the fluidized bed portion 201 is a perforated plate 141. The perforated plate 141 has a plurality of nozzles 141a. The nozzle 141a is a hole that penetrates the perforated plate 141 in the thickness direction. The hot air 131a for drying is introduced into the fluidized bed section 201 through the nozzle 141a of the perforated plate 141. The nozzle 141a preferably extends in the vertical direction. As a result, the hot air for drying 131a is ejected in the vertical direction, so that coal below the classification point can be more reliably blown to the freeboard portion 211.

And the hot air 131a for drying makes the coal X1 in the fluidized bed part 201 into the fluidized bed X21 (namely, fluidizes), and dries the coal X1. The hot air for drying 131a that has dried the coal X1 (that is, has taken water from the coal X1) is introduced to the freeboard unit 211. Further, the hot air for drying 131a blows off a part of the coal X1 onto the freeboard portion 211. After that, the hot air for drying 131a rises inside the freeboard portion 211 and is discharged from the drying chamber exhaust gas outlet 181 as the drying chamber exhaust gas 181a. Of the coal X1 in the freeboard section 211, the coal X4 below the classification point is discharged from the drying chamber exhaust gas outlet 181 together with the drying chamber exhaust gas 181a, and the coal X1 having a particle size larger than the classification point settles in the fluidized bed X21. Thereby, the coal X1 is classified.

Therefore, the drying chamber exhaust gas 181a contains coal X4. Here, in the present embodiment, the temperature of the drying chamber exhaust gas 181a is 90 to 100° C. when the temperature of the drying hot air 131a is maximum. When this condition is satisfied, the coal X4 contains a large amount of water. For example, coal X4 has a water content of more than 5% by mass. Furthermore, the temperature of coal X4 becomes 90 degrees C or less. Therefore, by supplying such coal X4 to the freeboard section 122 in the classification chamber 122, the temperature of the coal X5 can be controlled to 120 to 170°C.

The freeboard section 211 is an area above the fluidized bed section 201. The width of the freeboard portion 211 is designed so that it becomes wider toward the ceiling. Further, the height of the freeboard portion 211 may be designed to be 0.6 times or more the height of TDH described later. This further improves the classification accuracy. Details will be described later. The raw material inlet 160 is provided on the front end surface 120a of the fluidized bed body 120 in the length direction. The raw material input port 160 is connected to the hopper 165, and the coal X1 is input into the drying chamber 121 via the raw material input port 160. The drying chamber exhaust gas outlet 181 is provided on the ceiling of the freeboard portion 211. The hot air for drying 131a rises in the freeboard portion 211 and is discharged from the drying chamber exhaust gas outlet 181 as the drying chamber exhaust gas 181a.

Here, the particle size of the coal X4, that is, the classification point in the drying chamber 121 is preferably smaller than the classification point in the classification chamber 122. This is because when the classification point in the drying chamber 121 is equal to or higher than the classification point in the classification chamber 122, the proportion of coarse particles in the classification chamber 122 increases, so that the classification accuracy decreases. Specifically, it is preferable that the average flow velocity of the drying hot air 131a in the freeboard unit 211 is smaller than the average flow velocity of the classification hot air 132a in the freeboard unit 212. Here, the average flow velocity of the hot air 131a for drying in the freeboard part 211 is represented by the following formula (2).

U ₀ 1 =hot air volume (m ³ /s)÷dry room freeboard area (m ² )...(2)

Here, in the formula (2), U ₀ 1 represents the average flow velocity of the drying hot air 131a in the freeboard portion 211. The amount of hot air is the amount of hot air for drying 131a introduced into the plenum chamber 131 (the volume of hot air for drying 131a introduced into the plenum chamber 131 per unit time), and the freeboard area of the drying chamber is the freeboard portion 211. Is a flat cross-sectional area of. Therefore, in order to adjust the average flow velocity under a constant air volume, the plane cross-sectional area of the freeboard portion 211 may be adjusted. The formula (2) is an example of a mathematical formula for calculating the average flow velocity of the drying hot air 131a, and the calculation method of the average flow velocity is not particularly limited. For example, the average flow velocity of the drying hot air 131a may be calculated in consideration of the water vapor evaporated from the fluidized bed X21. The average flow velocity of the classification hot air 132a in the freeboard section 212 will be described later. Here, by designing the height of the freeboard portion 211 to be 0.6 times or more the height of TDH, the classification accuracy in the drying chamber 121 is improved, so that the ratio of coarse particles in the classification chamber 122 can be more reliably ensured. Can be reduced to

The plenum chamber 131 is a part into which the hot air for drying 131a is introduced from the outside. The hot air for drying 131a introduced into the plenum chamber 131 is introduced into the fluidized bed section 201 through the nozzle 141a of the perforated plate 141. The value obtained by multiplying the air volume and the temperature of the hot air for drying 131a, that is, the heat input quantity, affects the water content removed from the coal X1. Further, the air volume affects the average flow velocity of the drying hot air 131a in the freeboard portion 211. The temperature also affects the flow velocity of the drying hot air 131a blown out from the nozzle 141a.

Therefore, the air volume and temperature of the drying hot air 131a are determined so that at least the following conditions (1a) and (2a) are satisfied. Furthermore, it is preferable that the conditions (3a) and (4a) are satisfied.
(1a) The average flow velocity of the drying hot air 131a in the freeboard portion 211 is smaller than the terminal velocity of the coal X1 at the classification point.
Thereby, the coal X4 below the classification point is discharged from the drying chamber exhaust gas outlet 181 together with the drying chamber exhaust gas 181a.
(2a) The fluidized bed X21 is formed. To form the fluidized bed X21, the superficial velocity of the fluidized bed of the drying hot air 131a blown out from the nozzle 141a needs to be, for example, 2.5 to 4.5 (m/s). Here, the superficial velocity of the fluidized bed is obtained by dividing the hot air flow rate (m ³ /s) introduced into the plenum chamber 131 by the area (m ² ) of the perforated plate 141.
(3a) Coal X1 is dried such that the water content of coal X1 is 2 to 5 mass %.
(4a) The average flow velocity of the drying hot air 131a in the freeboard unit 211 is made smaller than the average flow velocity of the classification hot air 132a in the freeboard unit 212 within the range satisfying the above (1a) to (3a).

Here, as will be described later, the plane cross-sectional areas of the freeboard portions 211 and 212 may differ depending on the plane cross-section inside the freeboard portion 211. Therefore, the average flow velocities of the hot air for drying 131a and the hot air for classification 132a also fluctuate in the freeboard portions 211 and 212. Therefore, more specifically, the condition (4a) is that “the minimum value of the average flow velocity of the drying hot air 131a is smaller than the minimum value of the average flow velocity of the classification hot air 132a”. In addition, when the plane cross-sectional area of the freeboard part 211 differs depending on the plane cross-section of the freeboard part 211, the minimum value of the average flow velocity of the hot air 131a for drying in the freeboard part 211 is the terminal speed of the coal X1 of the classification point. It should be about the same or smaller.

The following processing is performed in the drying chamber 121. First, the hopper 165 introduces the coal X1 into the drying chamber 121 from the raw material charging port 160. The coal X1 is continuously introduced. On the other hand, hot air 131a for drying is introduced into the plenum chamber 131. The air volume and temperature of the hot air 131a for drying are set so that the conditions (1a), (2a), and more preferably (3a), (4a) are satisfied.

The hot air 131a for drying is introduced into the coal X1 in the fluidized-bed part 201 through the nozzle 141a of the perforated plate 141. As a result, the coal X1 becomes the fluidized bed X21 and is dried. The dried coal X1 is introduced into the classification chamber 122 through the dry coal discharge port 112. The water content of the coal X1 is preferably 2 to 5 mass% when the coal X1 passes through the dry coal discharge port 112. Hereinafter, the water content of the coal X1 when the coal X1 passes through the dry coal discharge port 112 is also referred to as “boundary water content of the coal X1”. In this embodiment, the boundary water content of the coal X1 is preferably 2 to 5 mass%.

Furthermore, the hot air for drying 131a blows off part of the coal X1 into the freeboard portion 211. Then, the hot air for drying 131a that has deprived water of the coal X1 is introduced into the freeboard unit 211. The hot air for drying 131a rises in the freeboard portion 211 and is discharged from the drying chamber exhaust gas outlet 181 as the drying chamber exhaust gas 181a. Among the blown coal X1, the coal X4 having a classification point or lower rises in the freeboard portion 211 together with the drying hot air 131a and is discharged from the drying chamber exhaust gas discharge port 181. Among the blown coal X1, the coal X1 larger than that for classification is settled in the fluidized bed X21. By the above processing, the coal X1 is dried and classified.

The classification chamber 122 classifies the coal X1 by forming (that is, fluidizing) the coal X1 into a fluidized bed X22 by the classification hot air 132a. That is, the classification chamber 122 leaves the coal X1 larger than the desired classification point in the fluidized bed X22, and discharges the coal X5 below the classification point from the classification chamber exhaust gas outlet 182 together with the classification chamber exhaust gas 182a. The classification point is a parameter indicating the particle size of coal X1. If the classification point is too small, it becomes difficult to agglomerate the coal X1 discharged from the exhaust gas outlet 182 of the classification chamber, and if the classification point is too large, the agglomerated coal becomes brittle. Therefore, the classification point is set to 0.5 mm±0.05 mm, for example.

The classification chamber 122 includes a fluidized bed section 202, a freeboard section 212, a perforated plate 142, a coal discharge port 170, and a classification chamber exhaust gas discharge port 182.

The fluidized bed section 202 is an area where the fluidized bed X22 of the coal X1 is formed, and the bottom surface of the fluidized bed section 202 is a perforated plate 142. The perforated plate 142 has a plurality of nozzles 142a. The nozzle 142a is a hole that penetrates the perforated plate 142 in the thickness direction. The nozzle 142a preferably extends in the vertical direction. As a result, the classification hot air 132a is ejected in the vertical direction, so that coal below the classification point can be blown to the freeboard portion 212 more reliably. Particularly, in the present embodiment, since the coal X4 is supplied into the freeboard section 212, the coal X4 may settle in the fluidized bed X22. In this case, it is necessary to blow the coal X4 to the freeboard portion 212 again. When the nozzle 142a has a shape extending in the vertical direction, the classification hot air 132a is ejected in the vertical direction, so that the coal X4 can be blown to the freeboard portion 212 more quickly and reliably.

The hot air for classification 132a is introduced into the fluidized bed section 202 through the nozzle 142a of the perforated plate 142. And the classification hot air 132a classifies the coal X1 by making the coal X1 in the fluidized bed part 202 into the fluidized bed X22 (that is, fluidizing). That is, the classification hot air 132a blows off part of the coal X1 into the freeboard portion 212. The classification hot air 132a is introduced to the freeboard portion 212. The classification hot air 132a rises in the freeboard portion 212 and is discharged from the classification chamber exhaust gas outlet 182 as the classification chamber exhaust gas 182a. Of the coal X1 in the freeboard section 212, the coal X5 below the classification point is discharged from the classification chamber exhaust gas outlet 182 together with the classification chamber exhaust gas 182a, and the coal X1 having a particle size larger than the classification point settles in the fluidized bed X22. Thereby, the coal X1 is classified.

The freeboard section 212 is an area above the fluidized bed section 202. The width of the freeboard portion 212 may be designed so that it becomes wider toward the ceiling. Further, the height of the freeboard portion 212 may be designed to be 0.6 times or more the height of TDH described later. This further improves the classification accuracy. Further, the freeboard unit 212 is supplied with the coal X4 recovered from the drying chamber exhaust gas 181a. As a result, the coal X5 in the freeboard section 212 is cooled. Details will be described later.

The coal discharge port 170 is provided on the rear end surface 120b of the fluidized bed body 120 in the length direction. The classified coal X3 is discharged from the coal discharge port 170 to the outside of the fluidized bed apparatus 100. The classification chamber exhaust gas outlet 182 is provided on the ceiling of the freeboard portion 212. The hot air 132a for classification and the coal X1 below the classification point rise in the freeboard portion 212 and are discharged from the exhaust gas outlet 182 of the classification chamber.

The plenum chamber 132 is a part into which the classification hot air 132a is introduced from the outside. The classification hot air 132a introduced into the plenum chamber 132 is introduced into the fluidized bed section 202 through the nozzle 142a of the perforated plate 142. The hot air for classification 132a decomposes the pseudo particles by using the coal X1 as the fluidized bed X22, and blows a part of the coal X1 into the freeboard portion 212. The classification hot air 132a that has passed through the fluidized bed X22 is introduced into the freeboard section 212. The classification hot air 132a rises in the freeboard portion 212 and is discharged from the classification chamber exhaust gas outlet 182 as the classification chamber exhaust gas 182a. Of the coal X1 in the freeboard section 212, the coal X5 below the classification point is discharged from the classification chamber exhaust gas outlet 182 together with the classification chamber exhaust gas 182a. Further, the coal X5 is cooled by the coal X4 until the temperature reaches 120 to 170°C. The coal X4 is discharged from the classification chamber exhaust gas outlet 182 as a part of the coal X5. Coal X1 having a particle size larger than the classification point settles in the fluidized bed X22.

Here, the air volume of the classification hot air 132a (volume of the classification hot air 132a introduced into the plenum chamber 132 per unit time) affects the average flow velocity of the classification hot air 132a in the freeboard portion 212. The temperature also affects the flow velocity of the classification hot air 132a blown out from the nozzle 142a.

Therefore, the air volume and the temperature of the classification hot air 132a are determined so that at least the following conditions (1b) and (2b) are satisfied.
(1b) The average flow velocity of the classification hot air 132a in the freeboard section 212 is smaller than the terminal velocity of the coal X1 at the classification point.
As a result, the coal X1 below the classification point is discharged from the classification chamber exhaust gas outlet 182 together with the classification chamber exhaust gas 182a.
(2b) The fluidized bed X22 is formed. In order to form the fluidized bed X22, the superficial velocity of the fluidized bed 132a of the classification hot air 132a blown out from the nozzle 142a needs to be, for example, 2.5 to 4.5 (m/s). Here, the superficial velocity of the fluidized bed is obtained by dividing the amount of hot air (m ³ /s) introduced into the plenum chamber 132 by the area (m ² ) of the perforated plate 142. Further, the average flow velocity of the classification hot air 132a in the freeboard portion 212 is expressed by the following equation (3).

U ₀₂ =Amount of hot air (m ³ /s)÷freeboard area of classification room (m ² )...(3)

Here, in the formula (3), U ₀ 2 represents the average flow velocity of the classification hot air 132a in the freeboard portion 212. The hot air volume is the air volume of the classification hot air 132a introduced into the plenum chamber 132, and the classification chamber freeboard area is the flat cross-sectional area of the freeboard portion 212. Therefore, in order to adjust the average flow velocity under a constant air volume, the plane cross-sectional area of the freeboard portion 212 may be adjusted. In addition, when the plane cross-sectional area of the freeboard part 212 differs depending on the plane cross-section of the freeboard part 212, the minimum value of the average flow velocity of the classification hot air 132a in the freeboard part 212 is the terminal speed of the coal X1 at the classification point. It should be about the same or smaller. The air volume and temperature of the drying hot air 131a and the air volume and temperature of the classification hot air 132a may be controlled individually or collectively. In the latter case, the same fluidizing gas is divided and supplied to the plenum chambers 131 and 132. Further, the formula (3) is an example of a formula for calculating the average flow velocity of the classification hot air 132a, and the calculation method of the average flow velocity is not particularly limited. For example, the average flow velocity of the classification hot air 132a may be calculated in consideration of the water vapor evaporated from the fluidized bed X21.

The following processing is performed in the classification chamber 122. First, the dried coal X1 is introduced into the classification chamber 122, preferably the coal X1 having a water content of 2 to 5% by mass. The coal X1 is continuously introduced. On the other hand, the classification hot air 132a is introduced into the plenum chamber 132. The air volume and temperature of the classification hot air 132a are set so that the above conditions (1b) and (2b) are satisfied.

The classification hot air 132a is introduced into the coal X1 in the fluidized bed portion 202 through the nozzle 142a of the perforated plate 142. As a result, the coal X1 becomes the fluidized bed X22. The classification hot air 132a that has passed through the fluidized bed X22 is introduced into the freeboard section 212. The classification hot air 132a rises in the freeboard portion 212 and is discharged from the classification chamber exhaust gas outlet 182.

In the fluidized bed X22, the pseudo particles are scrubbed and decomposed into a plurality of particles. Part of the coal X1 in the fluidized bed X22 is blown from the fluidized bed X22 into the freeboard section 212 by the hot air for classification 132a. Of the coal X1 in the freeboard section 212, the coal X5 below the classification point is discharged from the classification chamber exhaust gas outlet 182 together with the classification chamber exhaust gas 182a. Here, the coal X5 in the freeboard unit 212 is cooled by the coal X4 supplied to the freeboard unit 212. The temperature of the coal X5 is 120 to 170°C. On the other hand, coal X1 having a particle size larger than the classification point settles in the fluidized bed X22. Thereby, the coal X1 is classified.

The dried and classified coal X3 is discharged from the coal discharge port 170 to the outside. The coal X5 discharged from the exhaust gas outlet 182 of the classification chamber is collected by the high temperature coal collector 15 and conveyed to the kneader 35. Note that a plurality of partition walls 111 and 135 may be provided. In this case, the fluidized bed body 120 and the plenum chamber 130 are divided into three or more regions. Of these regions, one or a plurality of regions on the front end face 120a side may be the drying chamber 121, and one or a plurality of regions on the rear end face 120b side may be the classification chamber 122. The exhaust gas outlet is provided for each area.
<3. Freeboard shape>
Next, the shape of the freeboard portion 212 will be described in detail with reference to FIGS. 2 and 3. As shown in FIG. 2, the freeboard section 212 includes a first freeboard section 212a, a second freeboard section 212b, and a third freeboard section 212c.

The first freeboard portion 212a is formed above the fluidized bed portion 202. The first freeboard portion 212a is designed so that the width thereof becomes wider toward the ceiling of the fluidized bed body 120. The angle θ formed by the side wall of the first freeboard portion 212a and the horizontal plane is also referred to as the morning glory angle, and its value is preferably 65±5°. The width W ₀ of the fluidized bed portion 202 is constant in the lengthwise direction of the fluidized bed body 120.

The second freeboard portion 212b is formed on the upper side of the first freeboard portion 212a. The width W of the second freeboard portion 212b is constant in the length direction of the fluidized bed body 120. The third freeboard portion 212c is formed above the second freeboard portion 210b. The third freeboard portion 212c is designed, for example, so that the width becomes narrower toward the ceiling of the fluidized bed body 120. When the third freeboard portion 212c is provided, the classification hot air 132a flows more smoothly in the freeboard portion 212. The classification chamber exhaust gas outlet 182 is provided on the third freeboard portion 212c. The third freeboard unit 212c may be omitted. In this case, a horizontal ceiling is formed on the upper end surface of the second freeboard portion 212b, and the classification chamber exhaust gas outlet 182 is formed on this ceiling.

The height H of the freeboard portion 212 is from the bottom surface of the fluidized bed portion 202 (that is, the surface of the perforated plate 142) to the upper end surface of the third freeboard portion 212c (when the third freeboard portion 212c does not exist). It is defined as the distance to the upper end surface of the second freeboard portion 212b.

Then, the height of the freeboard portion 212 is preferably 0.6 times or more of TDH(m) represented by the following formula (1).

In the formula (1), W ₀ is the width (m) of the fluidized bed section 202, and U ₀ is the freeboard average flow rate (average flow rate in the second freeboard section 212b of the classification hot air 132a) (m/s ). Here, the free board part 212 is designed as described above for the following reason.

It is known that the dust generation intensity of each area in the freeboard portion 212 decreases as the height from the bottom surface of the fluidized bed portion 202 to each area increases (for example, "Zenz, FA and N." A. Weil: AIChE J., 4, 472 (1958), "Horio, H., T. Shibata and I. Muchi:'Fluidization', ed. )."reference). The present inventor further studied the correspondence relationship between the dust generation intensity of each area in the freeboard portion 212 and the height from the bottom surface of the fluidized bed portion 202 to each area. As a result, the present inventor, as shown in FIG. 3, has a constant and minimum dust generation intensity in a region where the height from the bottom surface of the fluidized bed portion 202 is TDH×0.6 (m) or more. Found.

Therefore, coal X5 below the classification point is blown from the fluidized bed X22 to the freeboard section 212, but coal X1 above the classification point is also blown from the fluidized bed X22. Here, the minimum value of the average flow velocity of the classification hot air 132a in the freeboard unit 212 (that is, the average velocity of the classification hot air 132a in the second freeboard unit) is approximately the same as the terminal velocity of the coal X1 at the classification point. Alternatively, since the coal X1 is set to be smaller, the coal X1 larger than the classification point settles in the fluidized bed X22.

However, if the height of the freeboard portion 212 is not sufficient, the coal X1 larger than the classification point may be discharged from the classification chamber exhaust gas outlet 182 before settling in the fluidized bed X22. On the other hand, in the region where the height from the bottom surface of the fluidized bed section 202 is TDH×0.6 (m) or more, the dust generation intensity becomes constant. Therefore, in a region where the height from the bottom surface of the fluidized bed section 202 is TDH×0.6 (m) or more, coal X5 below the classification point is flowing, and coal X1 above the classification point hardly exists. Becomes For the above reasons, the height of the freeboard portion 212 is preferably 0.6 times or more of TDH. For the same reason, it is preferable that the height of the freeboard portion 211 is 0.6 times or more of TDH. The TDH for the freeboard unit 211 is also calculated by the same mathematical formula as the mathematical formula (1), but in the formula (1), W ₀ is the width (m) of the fluidized bed unit 201, and U ₀ is the average freeboard flow velocity (Average flow velocity in the second freeboard portion of the hot air for drying 131a) (m/s).

The low-temperature coal supply unit 71 is connected to the side surface of the freeboard unit 212. The connection port 71a between the low temperature coal supply unit 71 and the freeboard 212 may be located above the fluidized bed X22. This is because when the connection port 71 is provided on the side surface of the fluidized bed X22, the coal X4 is heated by the fluidized bed X22, particularly the hot air for classification 132a, so that the cooling effect of the coal X4 is reduced. Other reasons include a decrease in the heating efficiency of the coal X1 and an increase in the proportion of pulverized coal in the coal X1 (that is, a decrease in the classification efficiency). The height H1 from (the center point of) the connection port 71a to the bottom surface of the fluidized bed portion 202 is preferably three times or more of the stationary height H2 of the fluidized bed X22. Thereby, the temperature of coal X5 can be controlled to 120-170 degreeC more reliably.

The position of the connection port 71a in the longitudinal direction of the fluidized bed is not particularly limited. This is because the coal X4 can mix with the coal X5 in the freeboard portion 212 and cool the coal X5 regardless of the position in the longitudinal direction. However, since the classification hot air 132a and the coal X5 that flow behind the freeboard portion 212 (on the rear end face 120b side) tend to have a higher temperature than those that flow at other positions, the connection port 71a has a freeboard portion. It is preferable to provide it as rearward as possible of 212. However, when the coal X4 settles in the fluidized bed X22, it is necessary to secure a time for the coal X4 to be blown off to the freeboard portion 212 again (to be washed in the fluidized bed X22 and blown off). Therefore, the connection port 71a is preferably provided at a position where the time (for example, 0.5 minutes) can be secured.

Further, it is preferable that the connection port 71a is not located directly above the coal discharge port 170. This is because when the connection port 71a is present at this position, the coal X4 (mainly composed of pulverized coal) may be mixed into the coal X3. When the coal X4 is mixed with the coal X3, the classification efficiency decreases. When the classification chamber 122 is divided into a plurality of regions, the connection port 71a is preferably provided in the region closest to the rear end face 120b. This is because the temperature of the coal X5 in this area becomes the highest.

<4. Reasons for setting the temperature of the exhaust gas in the drying chamber at 90 to 100°C>
In the present embodiment, the temperature of the drying chamber exhaust gas 181a is set to 90 to 100° C. when the temperature of the drying hot air 131a is maximum (that is, the fluidized bed apparatus 100 is operated at the maximum load). The reason will be described below with reference to FIG.

FIG. 4 is a graph showing an example of temperature distribution in the fluidized bed apparatus 100. The graphs L1 and L1' show the correspondence relationship between the exhaust gas temperature and the position in the longitudinal direction of the fluidized bed, that is, the distance from the front end surface 120a of the fluidized bed apparatus 100. Graphs L2 and L2' show the relationship between the position in the longitudinal direction of the fluidized bed and the temperature of the coal X1. The graph L3 shows the relationship between the position in the longitudinal direction of the fluidized bed and the hot air temperature. The exhaust gas temperature was measured by installing a plurality of thermometers in the longitudinal direction of the fluidized bed of the freeboard section (the area where the freeboard sections 211 and 212 are combined). Moreover, the temperature of the coal X1 was measured by installing a plurality of thermometers in the fluidized bed longitudinal direction of the fluidized bed section (the area where the fluidized bed sections 201 and 202 are combined). The hot air temperature was measured by providing a thermometer on the hot air supply pipe 311.

The graphs L1 and L2 are measured when the hot air temperature is maximum, and the graphs L1' and L2' are measured when the hot air temperature is lower than the maximum value. The graph L3 shows the maximum value of the hot air temperature.

As shown in FIG. 4, the temperature of the coal X1 is not heated above the dew point of the exhaust gas at a position close to the supply side of the coking coal (coal), that is, at a position where the longitudinal position in the fluidized bed is close to 0 [m]. Therefore, the water in the coal X1 is not evaporated at all, and the coal X1 is not dried. Therefore, since the heat of the hot air supplied from the hot air generating furnace 11 is used only for heating the coal flowing in the fluidized bed apparatus 100, the coal temperature rises. Similarly, the exhaust gas temperature also rises.

Next, when the coal temperature reaches the dew point temperature of the exhaust gas, all the heat amount given by the hot air supplied to the fluidized bed apparatus 100 is used for evaporation of water in the coal, and enters the constant rate drying region where the coal temperature does not rise. .. In the constant rate drying region, of the moisture contained in the coal X1, the moisture present on the surface of the coal X1 first evaporates. That is, the moisture moves to the hot air. While water is present on the surface, the rate at which the water on the surface of the coal X1 moves to the hot air is rate-determining, and the water on the surface of the coal X1 decreases (evaporates) at a constant speed (constant decrease rate). When the coal X1 exists in the constant rate drying region, the coal temperature is constant at about 70 to 80°C. Further, the exhaust gas temperature also becomes constant at 90 to 100°C. Therefore, when the exhaust gas temperature is 90 to 100° C., a large amount of water, including surface water, remains in the coal X1. Specifically, the coal X1 contains 4% by mass or more of water. In the constant rate dry region, the morphology of the coal pseudo particles is maintained by the presence of surface water. The water content of coal X1 can be measured by sampling coal X1.

Further, when the moisture content in the coal is less than about 4% by mass, it becomes a rate-decreasing dry region. Here, a part of the heat quantity given to the coal by the hot air is used for drying the moisture in the coal, and the rest is used for heating the surface of the coal, so that the coal temperature rises again. In the rate-decreasing dry region, almost no water is present on the surface of the coal X1. Therefore, when the coal X1 is heated, the water present inside the coal X1 moves to the surface and the water that reaches the surface evaporates. In this way, diffusion of the inside of the coal particles is rate-determining due to the evaporation of water. Therefore, the rate of decrease in water content decreases. In this rate-reduced dry area, the water holding the bond of the coal pseudo particles is lost, so the coal pseudo particles are decomposed into the coal particles constituting the coal pseudo particles.

As described above, in the constant rate drying region, the coal temperature is about 70 to 80° C., and the coal X1 contains a large amount of water. Therefore, by including the constant rate drying area in the drying chamber 121, it is possible to recover the coal X4 having a low temperature and a high water content. Then, in the constant rate drying region, the exhaust gas temperature is 90 to 100°C. Therefore, by installing the partition wall 111 in the constant rate drying area, the constant rate drying area can be included in the drying chamber 121. In this case, the temperature of the exhaust gas 181a in the drying chamber is 90 to 100°C. The temperature of the drying chamber exhaust gas 181a can be measured by installing a thermometer at the drying chamber exhaust gas outlet 181. In other words, if the partition wall 111 is set so that the temperature of the drying chamber exhaust gas 181a is 90 to 100° C., the constant rate drying region can be included in the drying chamber 121. The drying chamber 121 may include a reduction rate drying region as long as the temperature of the drying chamber exhaust gas 181a is in the range of 90 to 100°C.

However, as shown by the graphs L1, L1', L2, and L2', the length of the constant rate drying region varies depending on the hot air temperature. Specifically, the starting point of the constant rate drying region is almost the same, but the lower the hot air temperature, the longer the constant rate drying region. Therefore, when the partition wall 111 is installed with reference to the constant rate drying region corresponding to the hot air temperature lower than the maximum value, the temperature of the drying chamber exhaust gas 181a may exceed 100° C. as the hot air temperature rises. is there. In this case, the ratio of the rate-reduced dry area in the drying chamber 121 is high. In this case, the temperature of the coal X4 also rises and the water content also decreases, so the cooling effect becomes low.

However, if the partition wall 111 is installed so that the temperature of the drying chamber exhaust gas 181a is 90 to 100° C. when the hot air temperature is maximum, the temperature of the drying chamber exhaust gas 181a is 90 to 100° C. even if the hot air temperature changes. Can be maintained at. Specifically, when the partition wall 111 is installed in the constant rate drying area, the decreasing rate drying area is not included in the drying chamber 121 even if the hot air temperature changes. Even if the partition wall 111 is installed such that the drying chamber 121 includes the rate-decreasing area, the rate-decreasing drying area occupied in the drying chamber 121 only decreases due to the change in the hot air temperature. Therefore, even if the hot air temperature changes, the temperature of the exhaust gas 181a in the drying chamber can be maintained at 90 to 100°C. For the above reasons, in the present embodiment, the temperature of the drying chamber exhaust gas 181a is set to 90 to 100° C. when the temperature of the drying hot air 131a is maximum.

<5. Reason why it is preferable to set the boundary water content to 2 to 5% by mass>
As described above, the coal X1 in the constant rate drying region has a low temperature and a high water content. Therefore, by installing the partition wall 111 so that the drying chamber 121 includes a constant rate drying region, it is possible to recover the coal X4 having a low temperature and a high water content. However, since a large amount of coal X1 is formed into pseudo particles, the recovery amount of coal X4 becomes small. On the other hand, in the rate-decreasing dry region, the pseudo particles of coal X1 collapse. Therefore, by installing the partition wall 111 so that the drying chamber 121 also includes the reduction rate drying area, the amount of coal X4 recovered increases. The cooling effect of the coal X4 becomes higher as the recovery amount of the coal X4 increases. However, if the proportion of the rate-reduced dry area in the drying chamber 121 is too high, the temperature of the coal X4 will rise too high, and the cooling effect of the coal X4 will rather decrease. Therefore, the present inventor examined the ratio of the rate-reduced dry region in the drying chamber 121, and found that the ratio of the rate-reduced dry region in the drying chamber 121 was within a range in which the boundary moisture value was 2% by mass or more. It was found that the higher the temperature, the higher the cooling effect of coal X4. On the other hand, when the amount of boundary water is too large, the amount of coal X4 recovered decreases. Therefore, the upper limit of the boundary moisture value is preferably 5% by mass. For the above reasons, the boundary moisture value is preferably 2 to 5 mass %.

Note that when the water content of the coal X1 input to the fluidized bed body 120 changes, the graphs L1 and L2 described above also change. That is, the boundary between the constant rate dry area and the decreasing rate dry area also changes. In this case, the position of the partition wall 111 at which the temperature of the drying chamber exhaust gas 181a becomes 90 to 100° C. and the boundary moisture amount becomes 2 to 5 mass% also changes.

Therefore, when the water content of the coal X1 changes, the position of the partition wall may be adjusted, but by adjusting the amount of heat input to the drying chamber 121, the temperature of the drying chamber exhaust gas 181a is set to 90 to 100° C., In addition, the boundary water content may be 2 to 5% by mass. Here, the amount of heat applied to the drying chamber 121 is a value obtained by multiplying the air volume of the drying hot air 131a by the temperature. Therefore, in order to adjust the amount of heat applied to the drying chamber 121, at least one of the amount and temperature of the hot air for drying 131a introduced into the plenum chamber 131 may be adjusted. In addition, when controlling the hot air for drying 131a and the hot air for classification 132a collectively, if the air volume of the hot air for drying 131a is reduced, the fluidized bed X22 may not be formed in the classifying chamber 122, and therefore the temperature may be decreased depending on the temperature. It is preferable to adjust the amount of heat.

<6. Dry Coal Classification Method Using Fluidized Bed Apparatus>
The dry classification method of coal X1 using the fluidized bed apparatus 100 is as follows. First, coal X1 is put into the drying chamber 121 from the hopper 165. Next, the coal X1 in the fluidized bed section 201 is made into a fluidized bed X21 by hot air 131a for drying. As a result, the coal X1 is dried. The hot air for drying 131a that has deprived the coal X1 of water is introduced into the freeboard unit 211. The hot air 131a for drying blows off a part of the coal X1 from the fluidized bed X21 to the freeboard section 211. The hot air for drying 131a rises in the freeboard portion 211 and is discharged from the drying chamber exhaust gas outlet 181 as the drying chamber exhaust gas 181a. Of the coal X1 in the freeboard unit 211, the coal X4 having a classification point or lower rises in the freeboard unit 211 together with the drying hot air 131a and is discharged from the drying chamber exhaust gas discharge port 181. Coal X1 having a particle size larger than the classification point settles in the fluidized bed X21. Thereby, the coal X1 is classified.

Therefore, the drying chamber exhaust gas 181a contains coal X4. Here, in the present embodiment, the temperature of the drying chamber exhaust gas 181a is 90 to 100° C. when the temperature of the drying hot air 131a is maximum. The drying chamber exhaust gas 181a is discharged from the drying chamber exhaust gas discharge port 181 together with the coal X4, and is introduced into the low temperature coal collector 13. The low temperature coal collector 13 collects the coal X4 from the drying chamber exhaust gas 181a. The recovered coal X4 is supplied to the freeboard section 212 of the classification chamber 122 through the low temperature coal supply section 71.

The dried coal X1 is introduced into the classification chamber 122 through the dry coal discharge port 112. Here, the boundary water content of the coal X1 is preferably 2 to 5 mass %. In the classification chamber 122, a part of the coal X1 is blown off to the freeboard section 212 by forming the coal X1 into the fluidized bed X22 by the classification hot air 132a. Then, the classification hot air 132a is introduced into the freeboard portion 212. The classification hot air 132a rises in the freeboard portion 212 and is discharged from the classification chamber exhaust gas outlet 182 as the classification chamber exhaust gas 182a. Among the blown coal X1, the coal X5 having a classification point or lower rises in the freeboard portion 212 together with the classification hot air 132a. Then, the coal X5 in the freeboard unit 212 is cooled to 120 to 170° C. by the coal X4 supplied to the freeboard unit 212. After that, the coal X5 is discharged to the outside through the classification chamber exhaust gas outlet 182 together with the classification chamber exhaust gas 182a. The coal X4 is discharged from the classification chamber exhaust gas outlet 182 as a part of the coal X5. Thereby, the coal X1 is classified.

The dried and classified coal X3 is discharged from the coal discharge port 170 to the outside. Then, the coal X3 is conveyed to the coke oven 50. On the other hand, the coal X5 discharged from the classification chamber exhaust gas outlet 182 is recovered by the high temperature coal collector 15 and conveyed to the kneader 35. The kneader 35 kneads the coal X5 and the binder to produce a kneaded product. The agglomeration machine 37 produces agglomerated coal by agglomerating the kneaded material. Here, since the temperature of the coal X5 is controlled to 120 to 170° C., the agglomerator 37 can produce agglomerated coal with high strength. The agglomerated coal is conveyed to the coke oven 50 together with the coal X5.

<7. Modification>
As another method of controlling the temperature of coal X5, which is a raw material of agglomerated coal, to 120 to 170°C, the low temperature coal supply unit 71 may have a flow rate adjusting function of low temperature coal (coal X4). A rotary type feeder is provided on the coal discharge side of the low-temperature coal collector 13 to control the amount of coal X4 collected from the drying chamber exhaust gas 181a to the classification chamber 122. When the supply amount is increased, the temperature of coal X5 which is a raw material of agglomerated coal can be lowered. Conversely, if the supply amount is decreased, the temperature of the coal X5 can be increased.

Next, the following example was performed in order to confirm that the temperature of the coal X5 was controlled to 120 to 170°C by the above-described embodiment. In this embodiment, the fluidized bed body 120 and the plenum chamber 130 are divided by a partition wall 111 into a drying chamber 121 and a classification chamber 122. The morning glory angle of the first freeboard portion 212a was set to 68 (°). Further, the height H of the freeboard portion 212 was set to 5.9 (m), and the TDH was set to 7.2 (m). Therefore, the height of the freeboard portion 212 is 0.8 times the height of TDH. The shape of the freeboard portion 211 is the same as that of the freeboard portion 212.

Further, the connection port 71a is provided on the side surface of the freeboard portion 212. The position of the connection port 71a is different from the position directly above the coal discharge port 170. Further, the height H1 from the connection port 71a to the bottom surface of the fluidized bed portion 202 is set to be three times the stationary height H2 of the fluidized bed X22. Further, the nozzles 141a and 142a of the perforated plates 141 and 142 are designed to extend in the vertical direction.

Then, the fluidized bed apparatus 100 was used to dry and classify the raw coal having a water content of 9 to 13 mass %. The treatment amount was 120 to 161 dry-t/h. Further, the classification point in the drying chamber 121 was 0.4 mm, and the classification point in the classification chamber 122 was 0.5 mm. Further, when the hot air temperature is maximum (330° C. in this embodiment), the exhaust gas temperature in the drying chamber is 90 to 100° C., and the amount of heat applied to the drying chamber 121 is 2% by mass of the boundary water content. Was prepared. The boundary water content was measured by sampling the coal X1 existing in the dry coal outlet 112, and the drying chamber exhaust gas temperature was measured by installing a thermometer at the drying chamber exhaust gas outlet 181. Then, while changing the hot air temperature (the temperature of the hot air for drying 131a, the temperature of the hot air for classification 132a) in the range of 220 to 320°C, the raw coal was dried and classified.

In parallel with the above process, the temperatures of coals X3 and X5 were measured. The temperature of the coal X3 was measured by sampling the coal X3 passing through the coal discharge port 170. The temperature of the coal X5 was measured by sampling the coal X5 immediately before being put into the kneading machine 35. The result is shown in FIG. "Pulverized coal temperature" in FIG. 5 indicates the temperature of coal X5, and "coarse-grained coal temperature" indicates the temperature of coal X3. As is clear from FIG. 5, even if the hot air temperature is changed, the temperature of the coal X5 is within the range of 120 to 170° C. (range indicated by the area A). Although the same treatment was performed with the boundary water content of 5% by mass, almost the same result was obtained. When the same treatment was performed with the boundary water content of 1% by mass, the temperature of the coal X5 tended to rise overall, but the temperature of the coal X5 was within the range of 120 to 170°C. .. Similarly, when the same treatment was performed with the boundary water content of 6% by mass, the temperature of the coal X5 tended to rise overall, but the temperature of the coal X5 stayed within the range of 120 to 170°C. It was

Therefore, it was confirmed that the temperature of the coal X5 can be controlled to 120 to 170° C. by the configuration of the above embodiment.

The preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings, but the present invention is not limited to these examples. It is obvious that a person having ordinary knowledge in the technical field to which the present invention pertains can come up with various changes or modifications within the scope of the technical idea described in the claims. Of course, it is understood that these also belong to the technical scope of the present invention.

11 Hot Air Generator 13 Low Temperature Coal Collector 15 High Temperature Coal Collector 35 Kneader 37 Agglomerator 50 Coke Oven 100 Fluidized Bed Apparatus 120 Fluidized Bed Main Body 121 Drying Room 122 Classification Room 130, 131, 132 Plenum Room 131a For Drying Hot air 132a Hot air for classification 141, 142 Dish plate 141a, 142a Nozzle 160 Raw material inlet 165 Raw coal hopper 170 Coal outlet 181 Drying chamber exhaust gas outlet 182 Classification chamber exhaust gas outlet 181a Drying chamber exhaust gas 182a Classification chamber exhaust gas 201, 202 Fluidized bed section 211, 212 Freeboard section 212a First freeboard section 212b Second freeboard section 212c Third freeboard section

Claims (7)

By making the coal supplied from the coking coal supply unit a fluidized bed by hot air for drying, a drying chamber for drying the coal,
By making the coal dried in the drying chamber into a fluidized bed with hot air for classification, a classification chamber for classifying the coal dried in the drying chamber,
A partition for partitioning the drying chamber and the classification chamber,
A low temperature coal supply unit for charging coal contained in the exhaust gas discharged from the drying chamber into the classification chamber from above the fluidized bed in the classification chamber,
When the temperature of the hot air for drying becomes maximum, the temperature of the exhaust gas discharged from the drying chamber becomes 90 to 100° C.,
The height from the connection port between the low temperature coal supply unit and the classification chamber to the bottom surface of the fluidized bed in the classification chamber is 3 times or more the static height of the fluidized bed in the classification chamber,
A fluidized bed apparatus, wherein the temperature of coal contained in the exhaust gas discharged from the classification chamber is controlled to 120 to 159 °C. The fluidized bed apparatus according to claim 1, wherein the drying chamber dries the coal supplied from the coking coal supply unit until the water content becomes 2 to 5% by mass. The fluidized bed apparatus according to claim 1 or 2, wherein a connection port between the low-temperature coal supply unit and the classification chamber is arranged at a position different from a position directly above the coal discharge port of the classification chamber. The drying chamber has a drying chamber freeboard portion formed above the fluidized bed in the drying chamber,
The classification chamber has a classification chamber freeboard portion formed above the fluidized bed in the classification chamber,
The average flow velocity of the exhaust gas flowing in the drying chamber freeboard unit is smaller than the average flow velocity of the exhaust gas flowing in the classification chamber freeboard unit, The flow according to any one of claims 1 to 3, Floor equipment. The fluidized bed apparatus according to claim 4, wherein a height of the drying chamber freeboard portion is 0.6 times or more of a transfer release height TDH represented by the following formula (1).
TDH/W ₀ =(2.7W ₀ -0.36-0.7)exp(0.75U ₀ *W ₀ -0.23)・・・(1)

In formula (1), W ₀ is the width of the fluidized bed in the drying chamber, and U ₀ is the average flow velocity of the gas flowing in the drying chamber freeboard section. The fluidized bed apparatus according to any one of claims 1 to 5, wherein a plurality of nozzles provided on a perforated plate that forms the bottom surfaces of the drying chamber and the classification chamber extend in the vertical direction. A method for drying and classifying coal, which comprises drying and classifying coal using the fluidized bed apparatus according to any one of claims 1 to 6.

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