JP6819267B2 - Fluidized bed system - Google Patents

Description

The present disclosure relates to a fluidized bed system including a fluidized bed chamber in which a fluidized bed of solids is formed.

A fluidized bed system using a fluidized bed formed by ejecting gas from below to upward in a fluidized bed chamber containing particulate solids is a drying, combustion, gasification, and granulation of solids. It is used in various fields such as.

In the fluidized bed system, a technique for equalizing the residence time of solids by providing a partition plate extending in the vertical direction in the fluidized bed chamber has also been developed (for example, Patent Document 1).

Japanese Unexamined Patent Publication No. 10-160348

However, the solids handled by the fluidized bed system may vary in size (particle size). In this case, relatively large solid matter stays (accumulates) below the partition plate, and the lower part of the partition plate is blocked by the solid matter, so that the operation cannot be performed. Therefore, there is a problem that the maintenance frequency increases.

In view of such problems, it is an object of the present disclosure to provide a fluidized bed system capable of reducing the amount of solid matter deposited under the partition plate per unit time.

In order to solve the above problems, the fluidized bed system according to one aspect of the present disclosure has a fluidized bed having an inlet provided on the first side wall and an outlet provided on the second side wall facing the first side wall. The distance between the chamber and the first side wall and the second side wall in the fluidized bed chamber is 0.8 to 3 times the distance B represented by the following formula (A). It is provided so as to be within the range, and is provided with a partition plate for partitioning the fluidized bed chamber into an upstream chamber and a downstream chamber while maintaining a state of communication with the bottom surface.

Further, the bottom surface of the fluidized bed chamber may be provided with an outlet provided between the vertically lower portion of the partition plate and the vertically lower portion of the second side wall.

It is possible to reduce the amount of solid matter accumulated under the partition plate per unit time.

It is a figure explaining the fluidized bed system. It is a figure explaining the distance between a partition plate and a 2nd side wall. It is a figure explaining the result of simulating the movement of particles by the difference of the distance in a downstream chamber. It is a figure explaining the simulation result of the mass flow rate from the upstream chamber to the downstream chamber by the difference of a distance.

An embodiment of the present disclosure will be described in detail below with reference to the accompanying drawings. The dimensions, materials, other specific numerical values, etc. shown in such an embodiment are merely examples for facilitating understanding, and do not limit the present disclosure unless otherwise specified. In the present specification and drawings, elements having substantially the same function and configuration are designated by the same reference numerals to omit duplicate description, and elements not directly related to the present disclosure are omitted from the illustration. To do.

(Fluidized Bed System 100)
FIG. 1 is a diagram illustrating a fluidized bed system 100. In the present embodiment, a configuration in which the fluidized bed system 100 dries brown coal as a fluidized medium will be described as an example. In FIG. 1, the gas flow is indicated by a solid arrow, and the flow of a fluid medium is indicated by a broken line arrow. As shown in FIG. 1, the fluidized bed system 100 includes an introduction unit 110 and a fluidized bed unit 210.

(Introduction part 110)
The introduction unit 110 includes a conveyor 112, a hopper 114, an introduction pipe 116, and an introduction valve 118. The conveyor 112 conveys lignite from the lignite source to the hopper 114. The hopper 114 temporarily stores the lignite conveyed by the conveyor 112. The introduction pipe 116 is a pipe that communicates the hopper 114 and the fluidized bed portion 210 (the inlet 222a of the fluidized bed chamber 220). The introduction valve 118 is provided in the introduction pipe 116 and adjusts the opening degree of the introduction pipe 116.

(Fluidized bed section 210)
The fluidized bed section 210 includes a fluidized bed chamber 220, a fluidized gas supply section 230, a heat transfer section 240, an overflow section 250, a cyclone 260, and a partition plate 270.

The fluidized bed chamber 220 is a rectangular parallelepiped container. The first side wall 222 that constitutes the fluidized bed chamber 220 is provided with an input port 222a. Further, among the side walls constituting the fluidized bed chamber 220, a discharge port 224a is provided on the second side wall 224 facing the first side wall 222. An introduction pipe 116 is connected to the inlet 222a, and lignite is introduced into the fluidized bed chamber 220 through the inlet 222a. Then, the fluidized bed chamber 220 accommodates the introduced lignite.

The fluidized gas supply unit 230 supplies the fluidized gas (for example, water vapor) from the bottom surface of the fluidized bed chamber 220. Specifically, the fluidized gas supply unit 230 includes a wind box 232, a fluidized pipe 234, and a blower 236.

The air box 232 is provided below the fluidized bed chamber 220. The upper portion of the air box 232 is formed of a dispersive plate 232a that also functions as the bottom surface of the first side wall 222 and is breathable. The dispersion plate 232a is composed of, for example, a plate provided with a plurality of holes having a diameter smaller than the particle size of brown coal, or a plate provided with a nozzle. The flow pipe 234 is connected to the air box 232. Further, the flow pipe 234 is provided with a blower 236 for feeding the fluidized gas. The blower 236 supplies the fluidized gas to the fluidized pipe 234 at a flow rate at which a fluidized bed of lignite is preferably formed in the fluidized bed chamber 220.

In this way, the fluidized gas is supplied into the fluidized bed chamber 220 by the blower 236. The fluidized gas causes lignite to flow in the fluidized bed chamber 220 to form a fluidized bed of lignite. Further, the blower 236 evaporates a part of the water contained in the lignite by bringing the fluidized gas into contact with the lignite.

The heat transfer unit 240 is composed of, for example, a pipe through which a heat medium flows, and is arranged in a fluidized bed chamber 220 (in this embodiment, an upstream chamber 272 described later). The heat transfer unit 240 heats lignite with the heat of the heat medium in the process of distributing the heat medium. With the configuration including the heat transfer unit 240, heat exchange is performed between the heat medium and the fluidized gas in the fluidized bed chamber 220, and the fluidized gas moving upward can be further heated. Therefore, the drying of lignite by the fluidized gas is further promoted.

The overflow portion 250 includes an overflow pipe 252 connected to the discharge port 224a. The overflow unit 250 sends out the lignite that has overflowed from the discharge port 224a to the outside. Specifically, when lignite is introduced into the fluidized bed portion 210 (inside the fluidized bed chamber 220) through the inlet 222a, the volume of the fluidized bed increases by the volume integral of the introduced lignite. Then, the lignite (fluidized bed) overflows from the discharge port 224a and is sent to the outside through the overflow pipe 252.

The cyclone 260 is connected to a vent 226a formed in the ceiling 226 of the fluidized bed chamber 220. The cyclone 260 solid-gas separates the fluidized gas discharged from the fluidized bed chamber 220 through the vent 226a. The fluidized gas that has passed through the fluidized bed chamber 220 contains lignite. Therefore, by providing the cyclone 260, the fluidized gas (including lignite) discharged from the fluidized bed chamber 220 through the vent 226a is solid-gas separated. Then, the fluidized gas separated by the cyclone 260 is exhausted to the outside. Further, the lignite separated by the cyclone 260 is sent to the outside.

In this way, the undried brown coal is introduced into the fluidized bed chamber 220, the brown coal is heated by the fluidized gas supply unit 230 and the heat transfer unit 240, and a part of water is evaporated and removed from the brown coal. On the other hand, to explain the flow of lignite, the lignite introduced into the fluidized bed chamber 220 through the inlet 222a becomes a fluidized bed in the fluidized bed chamber 220, moves in the fluidized bed chamber 220, and flows into the discharge port 224a and overflow. It is discharged from the inside of the fluidized bed chamber 220 to the outside through the pipe 252.

By the way, the size (particle size) of lignite varies. Therefore, when the flow velocity of the fluidized gas supplied by the blower 236 is set so that relatively small particles (hereinafter, referred to as “small particles”) can form a fluidized bed, relatively large particles (hereinafter, “small particles”) are set. The "large particles") do not flow and accumulate in the lower part of the fluidized bed chamber 220. On the other hand, if the flow velocity is set so that the large particles can form a fluidized bed, the small particles are scattered and discharged to the outside through the vent 226a. Therefore, the blower 236 supplies the fluidized gas at a flow velocity at which particles having an average particle size can form a fluidized bed. However, the moving speed in the fluidized bed chamber 220 differs depending on the size of the particles, and the residence time of the particles in the fluidized bed chamber 220 differs. Therefore, lignite may be discharged without being dried.

Therefore, in the fluidized bed portion 210 of the present embodiment, a partition plate 270 is provided in the fluidized bed chamber 220. The partition plate 270 is provided between the first side wall 222 and the second side wall 224 in the fluidized bed chamber 220, apart from the ceiling 226 and the bottom surface (dispersion plate 232a) of the fluidized bed chamber 220. Further, the partition plate 270 is provided substantially parallel to the first side wall 222 and the second side wall 224. The partition plate 270 is connected to both side walls other than the first side wall 222 and the second side wall 224 among the side walls constituting the fluidized bed chamber 220, and the inside of the fluidized bed chamber 220 is divided into an upstream chamber 272 and a downstream chamber 274. To do. The upstream chamber 272 is formed between the first side wall 222 and the partition plate 270, and the downstream chamber 274 is formed between the partition plate 270 and the second side wall 224. Therefore, the fluidized bed (brown coal) formed in the upstream chamber 272 moves to the downstream chamber 274 through the lower part of the partition plate 270. Further, in the present embodiment, the partition plate 270 is provided in the fluidized bed chamber 220 so that the horizontal cross-sectional area (volume) of the downstream chamber 274 is smaller than that of the upstream chamber 272.

Due to the configuration including the partition plate 270, the particles pass below the partition plate 270 regardless of the size. This makes it possible to avoid a situation in which the particles move from the input port 222a to the discharge port 224a in the shortest distance. Therefore, it is possible to reduce the variation in the residence time (equalize (average) the residence time).

On the other hand, when the partition plate 270 is provided, lignite may be clogged below the partition plate 270 (between the lower end of the partition plate 270 and the dispersion plate 232a). Specifically, large particles that do not fluidize stay in the lower part of the fluidized bed chamber 220. Then, large particles are deposited, and the large particles block the lower part of the partition plate 270.

Therefore, an outlet 280 is provided on the bottom surface (dispersion plate 232a) of the fluidized bed chamber 220, and large particles are extracted from the fluidized bed chamber 220 through the outlet 280. An extraction pipe 282 is connected to the outlet 280, and an opening / closing valve 284 is provided in the extraction pipe 282.

However, the particles extracted from the extraction port 280 are insufficiently dried. Specifically, the heat transfer unit 240 is provided above the dispersion plate 232a by a predetermined distance in consideration of ensuring the function of the dispersion plate 232a, maintenance, and the like. Therefore, the particles deposited in the lower part of the fluidized bed chamber 220 are insufficiently dried. Therefore, the particles extracted from the extraction port 280 are insufficiently dried. Therefore, there is a demand for a technique for reducing the amount of particles extracted from the extraction port 280.

Therefore, the distance between the partition plate 270 and the second side wall 224 is devised to reduce the amount of particles staying at the bottom of the fluidized bed chamber 220 per unit time.

ここで、平均層高Ｈは、脈動する流動層の高さ（層高）の時間的な平均値である。 FIG. 2 is a diagram for explaining the distance between the partition plate 270 and the second side wall 224. In addition, in FIG. 2, the inlet 222a, the outlet 224a, the vent 226a, and the outlet 280 are omitted in FIG. 2 for easy understanding. As shown in FIG. 2, in the present embodiment, the distance R between the partition plate 270 and the second side wall 224 is within a range of 0.8 to 3 times the distance B represented by the following formula (A). In addition, a partition plate 270 is provided in the fluidized bed chamber 220.

Here, the average layer height H is a temporal average value of the height (layer height) of the pulsating fluidized bed.

By increasing the flow velocity of the particles in the downstream chamber 274, the particles staying in the lower part of the fluidized bed chamber 220 are lifted to the discharge port 224a. Specifically, the flow velocity of the particles in the downstream chamber 274 is calculated using the following formula (B).
Particle flow velocity = (input amount-extraction amount-overflow amount) / (R × L) ... Equation (B)
Therefore, the smaller the distance R, the higher the flow velocity of the particles in the downstream chamber 274.

However, if the distance R is less than 1.0 times the distance B (hereinafter referred to as "1.0B"), slugging (burst) occurs in the downstream chamber 274. When slugging occurs, the fluidized bed chamber 220 and the equipment on the downstream side (downstream of the fluidized bed chamber 220) are impacted. On the other hand, when the distance R exceeds 3.0 times the distance B (hereinafter referred to as "3.0B"), the bubbles do not grow and the large particles cannot be lifted, and the large particles become the bottom surface of the downstream chamber 274. Stay in.

FIG. 3 is a diagram for explaining the result of simulating the movement of particles due to the difference in distance R in the downstream chamber 274. Note that FIG. 3A shows a simulation result when the distance R is 1.0B, and FIG. 3B shows a simulation result when the distance R is 3.0B. In FIG. 3, only large particles having a particle size of 500 μm or more are shown.

As shown in FIG. 3A, when the distance R = 1.0B, the large particles in the downstream chamber 274 can reach (lift) the discharge port 224a. On the other hand, as shown in FIG. 3B, when the distance R = 3.0B, the flow velocity of the downstream chamber 274 is low, and large particles cannot reach the discharge port 224a.

Further, as the distance R in the downstream chamber 274 is reduced, the amount of large particles moving from the upstream chamber 272 to the downstream chamber 274 increases. FIG. 4 is a diagram for explaining the simulation result of the mass flow rate from the upstream chamber 272 to the downstream chamber 274 due to the difference in the distance R. 4 (a) shows the mass flow rate of particles having a particle size of 20 μm to 3000 μm, and FIG. 4 (b) shows an enlarged view of the mass flow rate of particles having a particle size of 500 μm to 1100 μm in FIG. 4 (a). Shown, FIG. 4 (c) shows an enlarged view of the mass flow rate in FIG. 4 (a) having a particle size of 1100 μm to 3000 μm. Further, in FIG. 4, the distance R = 1.0B is shown by a solid line, and the distance R = 3.0B is shown by a broken line.

As shown in FIG. 4, at a distance R = 1.0B, it can be seen that large particles having an average particle size of 500 μm or more move from the upstream chamber 272 to the downstream chamber 274. On the other hand, at a distance R = 3.0B, it was found that large particles having an average particle size of 500 μm or more hardly moved to the downstream chamber 274.

As described above, by setting the distance R within the range of 1.0B or more and 3.0B or less, the particles staying at the bottom of the fluidized bed chamber 220 can be efficiently moved to the discharge port 224a. As described above, the shorter the distance R, the higher the flow velocity of the downstream chamber 274. Therefore, the distance R is preferably 1.0B. However, even if the distance R is 0.8B, the durability of the fluidized bed chamber 220 can be maintained. Therefore, the distance R may be in the range of 0.8B or more and 3.0B or less.

Further, as shown in the following formulas (C) to (E), when the average layer height H of the downstream chamber 274 and the flow rate Qb of the fluidized gas supplied to the downstream chamber 274 per unit area are equal, the distance The smaller R, the larger the bubble diameter Db.

As described above, the horizontal cross-sectional area of the downstream chamber 274 is smaller than that of the upstream chamber 272. That is, the distance R is smaller in the downstream chamber 274 than in the upstream chamber 272. Therefore, as shown in the above formulas (C) to (E), the size of the bubbles of the fluidized gas in the downstream chamber 274 is larger than that in the upstream chamber 272. That is, the fluidized bed formed in the downstream chamber 274 has a lower density than the fluidized bed in the upstream chamber 272. Therefore, the chimney effect can promote the movement of particles (brown coal) from the upstream chamber 272 to the downstream chamber 274.

Further, in the fluidized bed portion 210 of the present embodiment, lignite can smoothly move from the upstream chamber 272 to the downstream chamber 274, and most of the large particles can be discharged from the discharge port 224a. Therefore, the outlet 280 is provided on the bottom surface (dispersion plate 232a) of the fluidized bed chamber 220 between the vertically lower portion of the partition plate 270 and the vertical lower portion of the second side wall 224, preferably directly below the partition plate 270. Good. As a result, it is possible to avoid a situation in which the particles are blocked below the partition plate 270.

As described above, according to the fluidized bed system 100 according to the present embodiment, the partition plate 270 is provided in the fluidized bed chamber 220, and the distance R between the partition plate 270 and the second side wall 224 is within the above range. Therefore, the large particles can be guided to the discharge port 224a. This makes it possible to reduce the amount of solid matter deposited below the partition plate 270 per unit time. Therefore, the amount of particles extracted from the extraction port 280 can be reduced.

Although the embodiments have been described above with reference to the accompanying drawings, it goes without saying that the present disclosure is not limited to such embodiments. It is clear that a person skilled in the art can come up with various modifications or modifications within the scope of the claims, and it is understood that they also naturally belong to the technical scope.

For example, in the above embodiment, lignite as a fluid medium has been described as an example. However, the type of fluid medium is not limited as long as it is a particulate solid.

Further, in the above embodiment, the configuration in which the fluidized bed portion 210 dries brown coal has been described as an example. However, if the fluidized bed system 100 can form a fluidized bed of a solid material and treat the solid material (drying, combustion, gasification, granulation, etc.), the fluidized bed unit 210 can perform the treatment. There is no limit.

Further, in the above embodiment, the configuration in which the partition plate 270 is provided apart from the ceiling 226 and the bottom surface (dispersion plate 232a) of the fluidized bed chamber 220 has been described as an example. However, the shape of the partition plate 270 is not limited as long as it can be divided into the upstream chamber 272 and the downstream chamber 274 while maintaining the state of communication with the bottom surface. For example, the partition plate may be a plate extending from the ceiling 226 to the bottom surface and having holes at the upper and lower portions, or a plate having holes only at the lower portion. Further, a part of the partition plate may be connected to the ceiling 226 or the bottom surface.

Further, in the above embodiment, the configuration in which the fluidized bed portion 210 is provided with the outlet 280 has been described as an example. However, when the distance R from the partition plate 270 to the second side wall 224 is set to a distance R at which all the particles can be discharged from the discharge port 224a, the extraction port 280 can be omitted.

The present disclosure can be used in a fluidized bed system including a fluidized bed chamber in which a fluidized bed of solids is formed.

100 Fluidized bed system 220 Fluidized bed chamber 222 1st side wall 222a Input port 224 2nd side wall 224a Discharge port 226 Ceiling 232a Dispersion plate (bottom surface)
270 Partition plate 272 Upstream chamber 274 Downstream chamber 280 Exit

Claims (2)

A fluidized bed chamber having an inlet provided on the first side wall and a discharge port provided on the second side wall facing the first side wall.
The distance between the first side wall and the second side wall in the fluidized bed chamber is within the range of 0.8 to 3 times the distance B represented by the following formula (A). A partition plate that divides the fluidized bed chamber into an upstream chamber and a downstream chamber while maintaining a state of communication with the bottom surface.
Fluidized bed system with.

The fluidized bed system according to claim 1, further comprising an outlet provided between the bottom surface of the fluidized bed chamber and the vertically lower portion of the partition plate to the vertically lower portion of the second side wall.

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