JP2014037907A - Fluidized bed apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a novel and improved fluidized bed apparatus capable of controlling the classification point of a raw material more precisely and improving a classifying efficiency.SOLUTION: According to an aspect of the invention, a fluidized bed apparatus comprises: a fluidized bed section where a fluidized bed of a raw material is formed by a fluidizing gas; a first free board section formed on an upper side of the fluidized bed section having a bosh angle made between a side wall and a horizontal plane and ranging within 65° ± 5°; a second free board section formed on an upper side of the first free board section; and a discharge port formed on an upper side of the second free board section for discharging the fluidizing gas.

Description

  The present invention relates to a fluidized bed apparatus.

  As a technique for producing coke, a technique for drying and classifying coal before carbonization is proposed. A fluidized bed apparatus has been proposed as an apparatus for 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 main body includes a countersink plate in which a plurality of nozzles are formed, and coal is placed on the countersunk plate. The plenum chamber is provided below the eye plate. Fluidized gas for fluidizing coal is introduced into the plenum chamber. The fluidizing gas is jetted into the fluidized bed main body through the nozzle of the eye plate.

  In such a fluidized bed apparatus, the following processing is performed. That is, coal is introduced into the fluidized bed body while fluidized gas is introduced into the plenum chamber. The fluidizing gas is jetted into the fluidized bed main body from the nozzle of the plate. Thereby, fluidization gas fluidizes coal. That is, coal is made into a fluidized bed by fluidizing gas. The fluidized gas that has passed through the fluidized bed passes through the free board section and is then discharged from the discharge port.

  Here, a part of the coal in the fluidized bed main body (mostly fine powder having a particle size of 0.3 mm or less) is blown off into the free board portion by the fluidizing gas. When the coal in the freeboard section has a speed exceeding the terminal speed, it is discharged from the discharge port together with the fluidizing gas, but when it has a speed equal to or lower than the terminal speed, the coal settles in the fluidized bed. The terminal speed is determined by the coal particle size.

  Therefore, conventionally, the terminal velocity is calculated based on the particle size to be classified (also referred to as classification point or classification particle size), and the average flow velocity of the fluidized gas in the freeboard section is adjusted based on this terminal velocity. It was. Specifically, the average flow velocity of the fluidized gas in the freeboard part was adjusted by adjusting the amount of hot air of the fluidized gas introduced into the plenum chamber and the flat cross-sectional area of the freeboard part. Here, the plane cross-sectional area is the area of the horizontal cross section of the free board portion. Thereby, since the coal below the classification point is discharged from the outlet, the coal can be classified.

Japanese Patent No. 3290574

  However, since the above classification method only controls the classification point only by the average flow velocity of the fluidized gas in the freeboard section, the classification accuracy (classification controllability) is not sufficient. Specifically, for example, even if the classification point is set to 0.5 mm and the average flow velocity of the fluidized gas in the free board part is set accordingly, the shape of the horizontal section of the free board part (for example, the vertical and horizontal directions of the free board part) Ratio), the classification points varied in the range of 0.3 to 0.5 mm. Further, the mixing ratio of fine powder into the coal after drying, that is, the classification efficiency, also varied depending on the shape of the horizontal cross section of the free board portion.

  On the other hand, Patent Document 1 discloses a fluidized bed apparatus that performs drying and classification of coal. In this fluidized bed apparatus, the fluidized bed main body is divided into a plurality of regions by a partition, and the average flow velocity of the fluidized gas in the free board portion is adjusted for each region. According to this technique, the classification point can be adjusted for each region. However, even with this technique, the classification point is controlled only by the average flow velocity of the fluidized gas in the freeboard section. Moreover, in this technique, since the average flow velocity of the fluidized gas in the free board portion is adjusted for each region, there is another problem that the moisture content of the coal discharged from the fluidized bed apparatus varies. If the moisture content is high, a large amount of energy is required in the coke oven in the subsequent process, and the quality of the coke varies. On the other hand, when the moisture content is low, coal may ignite.

  Therefore, the present invention has been made in view of the above problems, and the object of the present invention is to control the classification point more accurately and improve the classification efficiency. It is to provide a new and improved fluidized bed apparatus.

  In order to solve the above-described problems, according to an aspect of the present invention, a fluidized bed part in which a fluidized bed of raw material is formed by fluidized gas, and an angle formed between a side wall and a horizontal plane is formed above the fluidized bed part A first free board part having a morning glory angle of 65 ° ± 5 °, a second free board part formed on the upper side of the first free board part, and a second free board A fluidized bed apparatus is provided, characterized in that the fluidized bed apparatus is provided with a discharge port that is formed on the upper side of the section and through which the fluidized gas is discharged.

Here, the ratio W / W ₀ between the width W ₀ of the fluidized bed portion and the width W of the second free board portion may be larger than 1.7 and smaller than 2.1.

  Furthermore, the height from the lower end surface of the fluidized bed portion to the upper end surface of the second free board portion may be not less than 0.6 times the transport release height TDH represented by the following formula (1).

  Further, the height of the fluidized bed may be 1.5 to 2 times the thickness of the stationary layer.

  As described above, according to the present invention, the morning glory angle θ is a value in the range of 65 ° ± 5 °, so the fluidized bed apparatus more accurately discharges the raw material below the classification point from the discharge port, Raw materials larger than the classification point can be more accurately settled in the fluidized bed. Therefore, the fluidized bed apparatus can control the classification point of the raw material more accurately. In other words, the fluidized bed apparatus can suppress variation in classification points. Furthermore, the fluidized bed apparatus can improve the classification efficiency.

It is a sectional side view showing the schematic structure of the fluidized bed apparatus concerning the embodiment of the present invention. It is a sectional side view which shows schematic structure of an agglomerated coal manufacturing apparatus. It is explanatory drawing which shows C-C 'cross-sectional shape and flow velocity distribution of a free board part. It is explanatory drawing which shows a flow velocity distribution in detail. It is a sectional side view which shows the other example of a fluidized bed apparatus. It is a graph which shows the correspondence of a morning glory angle and classification granularity (classification point). It is a graph which shows the correspondence of morning glory angle and classification efficiency. W / W ₀ and classification particle size is a graph showing a relationship between a (classification point).

  Exemplary embodiments of the present invention will be described below in detail with reference to the accompanying drawings. In addition, in this specification and drawing, about the component which has the substantially same function structure, duplication description is abbreviate | omitted by attaching | subjecting the same code | symbol.

<1. Configuration of fluidized bed equipment>
First, based on FIG. 1, the structure of the fluidized bed apparatus 100 is demonstrated. As shown in FIG. 1, the fluidized bed apparatus 100 includes a fluidized bed main body 120, a plenum chamber 130, and a hopper 165. The fluidized bed apparatus 100 is a so-called drying classifier, and uses the fluidized bed X2 to dry and classify the coal X1.

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

  That is, in this embodiment, the raw material introduced into the fluidized bed apparatus 100 is coal X1. Coal X1 contains about 9 to 10% by mass of water with respect to the total mass. Moreover, the average particle size of coal X1 is about 1-2 mm. Coal X1 contains coarse particles (particles having a particle size of 0.5 mm or more) and fine powders (particles having a particle size of 0.3 mm or less).

  The average particle size is measured as follows, for example. First, a plurality of sieves having different openings are prepared, and the coal X1 is divided into each of a plurality of particle size classifications using these sieves. And based on the median of each particle size division and the ratio (mass% with respect to the total mass of coal X1) of coal X1 which belongs to each particle size division, an arithmetic average value of particle size is measured as an average particle size. Coarse particles are particles belonging to a particle size category having a particle size of 0.5 mm or more, and fine powders are particles belonging to a particle size category having a particle size of 0.3 mm or less.

  Moreover, in this embodiment, although coal X1 was used as a raw material, of course, this invention is applicable to raw materials other than coal X1. The present invention is preferably applied to a raw material having the same specific gravity as coal X1.

  The fluidized bed main body 120 has a substantially rectangular shape in plan view, and includes a fluidized bed 200, a free board 210, a raw material inlet 160, a processed raw material outlet 170, and an exhaust gas outlet 180. Prepare. In general, the fluidized bed main body 120 forms the fluidized bed X2 by fluidizing the coal X1 with the fluidized gas 130a.

  The fluidized bed 200 is a region where a fluidized bed X2 of coal X1 is formed, and the bottom surface of the fluidized bed 200 is a countersink plate 140. The eye plate 140 has a plurality of nozzles 141. The nozzle 141 is a hole that penetrates the countersink plate 140 in the thickness direction.

  The free board part 210 is an upper area of the fluidized bed part 200. The width of the free board unit 210 is designed to be wider as it is closer to the ceiling. In the present embodiment, the free board portion 210 has a specific shape, thereby improving the controllability of the classification points and the classification efficiency. Details will be described later. The raw material inlet 160 is provided on the rear end surface 120 a in the length direction of the fluidized bed main body 120. The raw material input port 160 is connected to a hopper 165, and the coal X <b> 1 is input into the fluidized bed main body 120 through the raw material input port 160. The processed raw material outlet 170 is provided on the front end surface 120b of the fluidized bed main body 120 in the length direction. The dried coal X3 is discharged from the treated raw material outlet 170 to the outside of the fluidized bed apparatus 100.

  The exhaust gas discharge port 180 is provided on the ceiling of the fluidized bed main body 120. The fluidized gas 130a is mixed with water vapor generated from the coal X1 and a part of the coal X1 (mainly coal X1 having a low particle size) to become an exhaust gas 180a. The exhaust gas 180a rises in the free board portion and is discharged from an exhaust gas discharge port 180 provided on the ceiling of the fluidized bed main body 120.

  The plenum chamber 130 is a portion into which the fluidized gas 130a is introduced from the outside. The temperature of the fluidizing gas 130a is set according to how much moisture of the coal X1 is evaporated, for example. Specifically, the fluidizing gas 130a is supplied into the plenum chamber 130 at a temperature of, for example, room temperature to about 500 ° C. The fluidizing gas 130 a is introduced into the coal X <b> 1 in the fluidized bed main body 120 through the nozzle 141 of the countersink plate 140.

  And fluidization gas 130a forms fluidized bed X2 by fluidizing coal X1. Thereafter, the fluidized gas 130a is mixed with water vapor generated by the drying of the coal X1 and a part of the coal X1, and becomes the exhaust gas 180a. The exhaust gas 180 a rises in the free board part 210 and is discharged from an exhaust gas discharge port 180 provided on the ceiling of the fluidized bed main body 120. Here, the flow rate of the exhaust gas 180a in the free board part 210 is set according to the classification point. Details will be described later.

  In the fluidized bed apparatus 100, the following processing is performed. First, the hopper 165 introduces the coal X1 into the fluidized bed main body 120 from the raw material introduction port 160. Coal X1 is continuously introduced. On the other hand, the fluidized bed apparatus 100 introduces the fluidized gas 130 a into the plenum chamber 130. The fluidizing gas 130 a is introduced into the coal X <b> 1 in the fluidized bed main body 120 through the nozzle 141 of the countersink plate 140. Thereby, coal X1 in fluid bed main part 120 is fluidized. That is, coal X1 is made into fluidized bed X2 and dried. The dried coal X3 is discharged from the treated raw material outlet 170 to the outside of the fluidized bed apparatus 100. Although the residence time in the fluidized bed main body 120 of coal X1 is set according to the moisture content etc. of the coal X3 after drying, it will be 1 to 5 minutes, for example. On the other hand, the fluidized gas 130a is mixed with water vapor generated by drying the coal X1 and a part of the coal X1, and becomes the exhaust gas 180a. The exhaust gas 180 a rises in the free board part 210 and is discharged from an exhaust gas discharge port 180 provided on the ceiling of the fluidized bed main body 120. Thereby, coal X1 is dried. Thus, the fluidized bed apparatus 100 can produce coal X3 having a denser structure by drying coal X1 having a high water content. Thereby, coke with high intensity | strength can be manufactured at a post process.

  The fluidized bed apparatus 100 also classifies the coal X1 using the exhaust gas 180a. That is, the average flow velocity (see FIG. 4) in the second free board portion 210b of the exhaust gas 180a is set according to a desired classification point (for example, 0.5 mm). Thereby, the coal X1 below the classification point is discharged from the exhaust gas outlet 180 together with the exhaust gas 180a, and the coal X1 larger than the classification point settles on the fluidized bed X2. Thereby, coal X1 is classified. In this embodiment, as will be described later, since the shape and the like of the free board portion 210 are different from the conventional one, the classification point of the coal X1 can be controlled more accurately, and the classification efficiency is improved. Here, the classification efficiency is mass% of fine powder with respect to the total mass of coal X3. Thereby, in this embodiment, the dust generation of coal X3 and the carry over in a coke oven can be suppressed. Note that the coal X1 discharged together with the exhaust gas 180a from the exhaust gas discharge port 180 may be collected by a bag filter. The recovered coal X1 can be made into agglomerated coal by the agglomerated coal production apparatus 400 described later. Moreover, the fluidized bed apparatus 100 may perform only classification.

<2. Configuration of agglomerated coal production equipment>
Next, based on FIG. 2, the structure of the agglomerated coal manufacturing apparatus 400 is demonstrated. The agglomerated coal production apparatus 400 includes a hopper 410, a screw 420, and a roll compactor 430. The hopper 410 stores the coal X4 recovered by the bag filter. The screw 420 sequentially inputs the coal X4 in the hopper 410 into the roll compactor 430. The roll compactor 430 produces the agglomerated coal X5 by compressing the coal X4. Since the agglomerated coal X5 is obtained by pressure-bonding the coals X4, the caking property is improved. The agglomerated coal X5 may be mixed into the dried coal X3. Thereby, while being able to use coal X1 which is a raw material more efficiently, the intensity | strength of coke can be improved.

  The particle size distribution of the coal X4 varies depending on the classification point of the fluidized bed apparatus 100. From the viewpoint of the strength and stable productivity of the agglomerated coal X5, the classification point is preferably about 0.5 mm. When the classification point greatly exceeds 0.5 mm, the strength of the agglomerated coal X5 decreases. Moreover, when a classification point is much less than 0.5 mm, coal X4 falls between roll compactors 430, without being crimped | compressed. Therefore, by setting the classification point to about 0.5 mm, the strength of the agglomerated coal X5 is improved, and the agglomerated coal X5 is stably produced.

<3. Configuration of fluidized bed and free board>
Conventionally, the terminal velocity is calculated based on the classification point, and the average flow velocity of the fluidized gas in the free board portion is adjusted based on the terminal velocity. However, in this classification method, the classification point is controlled only by the average flow velocity of the fluidized gas in the freeboard section, so the classification accuracy is not sufficient. The classification efficiency also varied depending on the shape of the horizontal cross section of the free board.

  Therefore, the inventor paid attention to the shape of the free board part 210. And this inventor discovered that the circulation area | region of the waste gas 180a was formed by the wall of the free board part 210 by making the width | variety of the free board part 210 wide toward the ceiling of the fluidized bed main body 120. FIG. And this inventor sets coal X1 (for example, coarse grain) larger than a classification point to a circulation flow by setting the shape of the free board part 210, especially the morning glory angle (theta) (refer FIG. 3) mentioned later to a specific range. It was found that the coal X1 (e.g. fine powder) below the classification point rises efficiently by riding and sinking efficiently.

Hereinafter, based on FIG.1 and FIG.3, the detailed structure of the fluidized bed part 200 and the free board part 210 is demonstrated. FIG. 3A shows a CC ′ cross-sectional shape of the free board part 210. As described above, the fluidized bed 200 is a region where the fluidized bed X2 is formed. The width W ₀ of the fluidized bed 200 is constant in the length direction of the fluidized bed main body 120.

  The free board part 210 is divided into a first free board part (so-called morning glory part) 210a and a second free board part 210b. The first free board part 210 a is formed on the upper side of the fluidized bed part 200. The first free board part 210a is designed so that the width becomes wider as it is closer to the ceiling of the fluidized bed main body 120.

  The second free board part 210b is formed on the upper side of the first free board part 210a. The width W of the second free board part 210 b is constant in the length direction of the fluidized bed main body 120. An exhaust gas outlet 180 is connected to the upper end surface of the second free board part 210b (that is, the ceiling of the fluidized bed main body 120). Note that a third free board portion may be further provided above the second free board portion 210b. For example, the third free board portion is designed so that the width becomes narrower as it approaches the ceiling of the fluidized bed main body 120. When the third free board part is provided, the exhaust gas 180a flows more smoothly in the free board part 120.

  With such a configuration, the rising region 300 of the exhaust gas 180a and the circulation region 310 of the exhaust gas 180a are formed in the free board portion 210. An arrow 300a indicates the flow direction of the exhaust gas 180a in the rising region, and an arrow 310a indicates the flow direction of the exhaust gas 180a in the circulation region. Of the coal X1 in the rising region 300, the coal X1 below the classification point is discharged from the exhaust gas outlet 180 together with the exhaust gas 180a or moves to the circulation region 310. On the other hand, among the coal X1 in the rising region 300, the coal X1 larger than the classification point settles in the fluidized bed X2 or moves to the circulation region 310.

  The coal X1 in the circulation region 310 circulates in the circulation region 310 together with the exhaust gas 180a. Thereafter, the coal X1 larger than the classification point settles in the fluidized bed X2. On the other hand, the coal X1 below the classification point moves to the rising region 300 and is discharged from the exhaust gas outlet 180 together with the exhaust gas 180a in the rising region 300. In addition, since coal X1 has a high water content, it may be pseudo-particles in the free board part 210. Pseudo particles are particles in which particles of coal X1 are bound together by moisture. In the present embodiment, since the exhaust gas 180a in the circulation region 310 is circulated, the pseudo particles in the circulation region 310 are expected to be scrubbed by the exhaust gas 180a and other coal X1 and decomposed into the original particles. Is done. Among the decomposed particles, particles larger than the classification point settle on the fluidized bed X2, and particles below the classification point are discharged from the exhaust gas outlet 180 via the ascending region 300. Therefore, even if the pseudo particles larger than the classification point are formed by binding particles below the classification point, the fluidized bed apparatus 100 decomposes the pseudo particles and discharges the decomposed particles from the exhaust gas outlet 180. be able to.

A graph L1 shown in FIG. 3B shows the flow velocity distribution of the exhaust gas 180a in the section AA ′, and a graph L2 shown in FIG. 3C shows the flow velocity distribution of the exhaust gas 180a in the section BB ′. Show. The horizontal axis of FIG. 3B indicates the width direction position w of each point on the AA ′ cross section, that is, the length of the perpendicular line drawn from each point to the central axis LC. The center axis LC is an axis that passes through the center of the free board portion 210 in the width direction and extends in the vertical direction. The vertical axis represents the vertical direction (x direction) component v _x (hereinafter also simply referred to as the flow velocity v _x ) of the flow velocity of the exhaust gas 180a. The same applies to FIG. The flow velocity v _x peaks at the central axis LC. Further, the flow velocity v _x is reversed between positive and negative in the vicinity of the side wall (the exhaust gas 180a becomes a reverse flow).

  In addition, the flow velocity of the exhaust gas 180a at each point in the free board unit 210 can be obtained, for example, by solving a continuous equation and a Navia-Stokes equation simultaneously. Usually, a general-purpose fluid calculation package such as FLUENT may be used.

  Further, the average flow velocity of the exhaust gas 180a in the second free board part 210b is set according to the classification point. For example, when the classification point is about 0.5 mm, the average flow velocity is about 1.5 to 2.5 m / s, but finally, it may be appropriately adjusted while observing the operation state of the fluidized bed. Here, the average flow velocity of the exhaust gas 180a in the second free board section 210b is a value obtained by dividing the sum of the flow rates of the exhaust gas 180a in the B-B 'cross section by the B-B' cross sectional area. Specifically, it is calculated by equation (2) described later.

FIG. 4 shows a detailed calculation example of the flow velocity v _x . A graph L3 illustrated in FIG. 4 shows the flow velocity distribution in the right half of the free board unit 210. The flow velocity v ₀ indicates the terminal velocity of the coal X1 having a classification point particle size. Further, W is the width of the second free board section 210b as described above. Further, a / 2 indicates the width direction position corresponding to the terminal velocity v _0, in this example is about 4 / W. In this example, a classification point is a 0.5 (mm), the terminal velocity _{v 0} becomes 2.7 (m / s). Therefore, a / W is about 0.5. In addition, it is preferable that a / W will be about 0.5-0.6. When a / W is a value within this range, classification accuracy and classification efficiency are improved.

  The flow state of the exhaust gas 180a greatly changes depending on the morning glory angle θ, which is an angle formed by the side wall of the first free board part 210a and the horizontal plane. The inventor has found that when the morning glory angle θ is around 65 °, the classification point of the coal X1 can be more accurately controlled, and the classification efficiency is greatly improved. Specifically, in the present embodiment, the morning glory angle θ is a value within a range of 65 ° ± 5 °, and preferably a value within a range of 65 ° ± 2 °. When the morning glory angle θ is larger than 70 °, the circulation region 310 is greatly developed, and the fine powder classification (rising separation) is difficult to proceed. That is, the classification efficiency decreases (the classification efficiency value increases). On the other hand, when the morning glory angle θ is less than 60 °, the reverse flow velocity (downward velocity) of the exhaust gas 180a in the circulation region 310 increases, but the flow velocity of the central axis LC in the ascending region 300 also greatly increases. For this reason, coal X1 larger than the classification point among coal X1 in the rising region is unlikely to settle in fluidized bed X2. That is, the classification accuracy decreases (coal X1 larger than the classification point is easily discharged). For this reason, in this embodiment, the morning glory angle θ is set to a value within the range of 65 ° ± 5 °. When the morning glory angle θ is a value within the range, the above-described a / W is about 0.5 to 0.6.

Further, the width W ₀ of the fluidized bed section 200, by widening ratio W / W ₀ is the ratio of the width W of the second free board section, the flow conditions of the exhaust gas 180a is greatly changed. The present inventor has found that the classification point of coal X1 can be more accurately controlled and the classification efficiency is greatly improved when the widening ratio W / W ₀ is around 2.0. Specifically, in the present embodiment, the widening ratio W / W ₀ is preferably greater than 1.7 and smaller than 2.1. The widening ratio W / W ₀ is more preferably larger than 1.8 and smaller than 2.0. When the widening ratio W / W ₀ is 1.7 or less, the circulation region does not develop, and among the coals X1 in the ascending region, the coals X1 that are larger than the classification point are less likely to settle in the fluidized bed X2. That is, the classification accuracy decreases (coal X1 larger than the classification point is easily discharged). On the other hand, when the widening ratio W / W ₀ is 2.1 or more, the circulating flow in the circulation region 310 is not stabilized and the classification efficiency is lowered. For this reason, in this embodiment, it is preferable that the widening ratio W / W ₀ is larger than 1.7 and smaller than 2.1. In addition, when the widening ratio W / W ₀ is a value within the above-described range, the above-described a / W is about 0.5 to 0.6.

  Further, the height H from the lower end surface of the fluidized bed portion 200 (that is, the surface of the countersink plate 140) to the upper end surface of the second free board portion 210b is a conveyance release height represented by the following equation (1). It is preferably 0.6 times or more of TDH (Transport Distinguishing Height).

  Here, the free board average flow velocity Ug is expressed by the following equation (2).

Here, the amount of hot air is the volume of the fluidized gas 130a introduced into the plenum chamber 130 per unit time, and the unit is m ³ / s. The free board area is a BB ′ cross-sectional area.

  It is also an important requirement to secure the minimum flight distance required for classification. The speed at which the coal X1 jumps out from the surface of the fluidized bed X2 is often larger than the terminal speed of the coal X1. The large-diameter coal X1 immediately settles and settles in the fluidized bed X2, but the small-diameter coal X1 reaches higher. Accordingly, a flight distance is required for the coal X1 that has jumped out of the fluidized bed X2 to sink the coal X1 that is larger than the classification point into the fluidized bed X2.

  On the other hand, the particle concentration in the free board part 210 decreases exponentially in the x direction (height direction) from the surface of the fluidized bed X2, but shows a constant value above a certain height. This height is referred to as a transport release height TDH. On the other hand, the speed of the coal X1, which is larger than the classification point, is lower than the terminal speed by at least the transport release height TDH. That is, the minimum necessary flight distance required for classification is slightly lower than the transport release height TDH. Specifically, the height H may be 0.6 times or more of the transport release height TDH. From the viewpoint of equipment costs, the height H is preferably as low as possible within a range that satisfies the above-described conditions.

Further, the height H ₀ of the fluidized bed X2 is preferably 1.5 to 2 times the stationary layer thickness. The static layer thickness (static layer height) is the height when the fluidized bed X2 is not flowing. When the height H ₀ is less than 1.5 times the static layer thickness, the coal X1 does not flow sufficiently, and the coal X1 below the classification point is less likely to scatter. On the other hand, the height H ₀ may exceed twice the stationary layer thickness, since coal X1 greater than the classification point is scattered in numerous freeboard section 210, classification accuracy decreases.

  Thus, in the present embodiment, the morning glory angle θ is a value in the range of 65 ° ± 5 °, so the fluidized bed apparatus 100 more accurately discharges the coal X1 below the classification point from the exhaust gas outlet 180. On the other hand, the coal X1 larger than the classification point can be more accurately settled in the fluidized bed X2. Therefore, the fluidized bed apparatus 100 can control the classification point of the coal X1 more accurately. In other words, the fluidized bed apparatus 100 can suppress variations in classification points.

  Furthermore, since the fluidized bed apparatus 100 can discharge the coal X1 (for example, fine powder) below the classification point more accurately from the exhaust gas outlet 180, the classification efficiency can be improved.

Furthermore, since the widening ratio W / W ₀ is larger than 1.7 and smaller than 2.1, the fluidized bed apparatus 100 can control the classification point of the coal X1 more accurately and improve the classification efficiency. Can do.

  Furthermore, the height from the lower end surface of the fluidized bed portion 200 to the upper end surface of the second free board portion 210b is not less than 0.6 times the transport release height TDH, so that the classification point of the coal X1 can be more accurately determined. It can be controlled and the classification efficiency can be improved.

Furthermore, since the height H ₀ of the fluidized bed X2 is 1.5 to 2 times the static bed thickness, the fluidized bed apparatus 100 can more accurately control the classification point of the coal X1 and classify. Efficiency can be improved.

  Furthermore, the fluidized bed apparatus 100 can classify the coal X1 at a desired classification point by setting the average flow velocity of the exhaust gas 180a in the second free board portion 210b according to the classification point. Here, the classification point is preferably set to about 0.5 mm. This is because the agglomerated coal production apparatus 400 can stably produce the agglomerated coal X5 having a high strength. Further, the fluidized bed apparatus 100 can classify the coal X1 with as little hot air flow as possible.

<4. Modification>
In FIG. 5, the modification of the fluidized bed apparatus 100 is shown. In this modification, the fluidized bed main body 120, the plenum chamber 130, and the countersunk plate 140 are divided into the fluidized bed main bodies 121 and 122, the plenum chambers 131 and 132, and the countersunk plates 141 and 142 by the partition walls 111 and 135. A space 112 is formed at the lower end of the partition wall 111, and the coal X1 in the fluidized bed main body 121 moves to the fluidized bed main body 122 through the space 112. A fluidizing gas 131 a is introduced into the plenum chamber 131, and a fluidizing gas 132 a is introduced into the plenum chamber 132. Therefore, fluidized bed X21, X22 is formed in each of fluidized bed main bodies 121, 122. Further, exhaust gas exhaust ports 181 and 182 are provided in the fluidized bed main bodies 121 and 122, respectively. Exhaust gas 181a is discharged from the exhaust gas outlet 181 and exhaust gas 182a is discharged from the exhaust gas outlet 182.

  The fluidized bed apparatus 100 according to this modification is used, for example, for dry classification of coal X1. That is, the coal X1 is dried by the fluidized bed main body 121 at the front stage, and the coal X1 is classified by the fluidized bed main body 122 at the rear stage. Therefore, in this modification, at least the latter fluidized bed main body 122 has the above-described configuration. Two or more partition walls may be provided. In this case, the fluidized bed main body 120 and the like are divided into three or more. The last fluidized bed main body is used for classification of coal X1.

Next, examples of the present embodiment will be described. In this embodiment, first, the flow velocity distribution of the fluidized bed two-dimensional cross section is calculated using FLUENT as described above, and whether or not the flight trajectory of a single coal particle is calculated and discharged from the upper outlet in the flow velocity field. Judged. By calculating the flight trajectory of the single particle by changing the particle size (particle size) and the initial position (position in the width direction on the fluidized bed plate), the classification point is determined from the particle size of the discharged coal. The ratio of fine powder (0.3 mm or less) in coal staying in the fluidized bed (namely, classification efficiency) was estimated. In the present embodiment, in the fluidized bed apparatus 100 shown in FIG. 1, each parameter is fixed as follows, and then the morning glory angle θ and the widening ratio W / W ₀ are shaken, so that these values are suitable. The range was verified.

The fixed parameters are as follows:
Average particle size of coal X1 = 1.0 mm
Average flow velocity of the exhaust gas 180a in the second free board portion 210b = 2.0 (m / s)
Height H ₀ of fluidized bed X2 = 500 (mm)
Static layer thickness = 300 (mm)
Height H ₁ = 590 (mm) of the first free board part 210a
Height H _{2 of} second free board part 210b = 4410 (mm)
Height H = 5500 (mm) from the lower end surface of the fluidized bed portion 200 to the upper end surface of the second free board portion 210b
TDH = 8.0 (m)

Therefore, the height H ₀ of the fluidized bed X2 is 1.7 times the stationary layer thickness. The height H is 0.69 times TDH. Moreover, in the present Example, the design range (preferable range) of the classification point was set to 0.45 (mm) to 0.55 (mm). When the classification point is larger than 0.55 (mm), the strength of the agglomerated coal X5 is insufficient. On the other hand, when the classification point is less than 0.45 (mm), it is not easy to stably produce the agglomerated coal X5 (poor powder agglomeration failure). Moreover, the design range of classification efficiency (mass% of fine powder with respect to the total mass of coal X3) was set to 2 (mass%) or less. When the classification efficiency exceeds 2% by mass, dust generation and carry-over are likely to occur.

  Plots P1 and P2 in FIG. 6 show the correspondence between the morning glory angle θ actually measured in the present example and the classification points. The plot P1 is included in the design range, and the plot P2 is out of the design range. The curve L10 is an approximate curve derived from the plots P1 and P2. The least square method was used to derive the approximate curve L10.

  Plots P3 and P4 in FIG. 7 show the correspondence between the morning glory angle θ actually measured in this example and the classification efficiency. The plot P3 is included in the design range, and the plot P4 is out of the design range. The curve L11 is an approximate curve derived from the plots P3 and P4. The least square method was used to derive the approximate curve L11. When measuring the correspondence between the morning glory angle θ and the classification point (or classification efficiency), the average flow rate of the exhaust gas 180a in the second free board unit 210b (that is, the free board average flow rate) = 1.9 (m / S).

Plot P5, P6 in FIG. 8 shows the correspondence between the classification point and widening ratio W / W ₀ that is measured in this embodiment. The plot P5 is included in the design range, and the plot P6 is out of the design range. Curve L12 is an approximate curve derived from plots P5 and P6. The least square method was used to derive the approximate curve L12. When measuring the correspondence between the widening ratio W / W ₀ and the classification point, the average flow velocity of the exhaust gas 180a in the second free board portion 210b was set to 1.9 m / s, and the morning glory angle was set to 65 °.

6 to 8, it was demonstrated that the appropriate range of the morning glory angle θ is 65 ± 5 °. Moreover, it was demonstrated that the more preferable range of the morning glory angle θ is 65 ± 2 °. This is because in the latter range, the classification point is closer to 0.5 mm. Furthermore, it was proved that the appropriate range of the widening ratio W / W _{0 is} a range larger than 1.7 and smaller than 2.1. Further, it was proved that a more preferable range of the widening ratio W / W ₀ is a range larger than 1.8 and smaller than 2. This is because in the latter range, the classification point is closer to 0.5 mm.

  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 such 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.

DESCRIPTION OF SYMBOLS 100 Fluidized bed apparatus 120 Fluidized bed main body 130 Plenum chamber 130a Fluidized gas 140 Plate plate 141 Nozzle 160 Raw material inlet 165 Hopper 170 Processed raw material outlet 180 Exhaust gas outlet 180a Exhaust gas 200 Fluidized bed part 210 Free board part 210a 1st Free board part 210b Second free board part 300 Ascending region 310 Circulating region 400 Agglomerated coal production apparatus

Claims (4)

A fluidized bed portion in which a fluidized bed of raw material is formed by fluidized gas;
A first free board portion formed above the fluidized bed portion and having a morning glory angle which is an angle formed between the side wall and a horizontal plane within a range of 65 ° ± 5 °;
A second free board part formed on the upper side of the first free board part;
A fluidized bed apparatus, comprising: a discharge port formed on an upper side of the second free board portion and from which the fluidized gas is discharged. Wherein a width W ₀ of the fluidized bed section, the ratio W / W ₀ of the width W of the second freeboard section being less than 2.1 greater than 1.7, the flow of claim 1, wherein Floor equipment. The height from the lower end surface of the fluidized bed portion to the upper end surface of the second free board portion is not less than 0.6 times the transport release height TDH represented by the following formula (1). The fluidized bed apparatus according to claim 1 or 2.

The fluidized bed apparatus according to any one of claims 1 to 3, wherein the height of the fluidized bed is 1.5 to 2 times the stationary layer thickness.

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