JP6197530B2 - Fluidized bed dryer - Google Patents

Description

  The present invention relates to a fluidized bed drying apparatus that dries a water-containing substance while flowing it.

  In recent years, as an alternative to natural gas, a technique has been developed in which gasification raw materials such as coal, biomass, and tire chips are gasified to generate synthesis gas. Synthetic gas generated in this way is used for power generation systems, hydrogen production, synthetic fuel (synthetic petroleum) production, chemical fertilizer (urea) and other chemical products. Among the gasification raw materials used as the raw material for synthesis gas, coal, in particular, has a recoverable period of about 150 years, more than three times the recoverable period of oil, and reserves are unevenly distributed compared to oil. Therefore, it is expected as a natural resource that can be stably supplied over a long period of time.

  Coal is classified into peat, lignite, lignite, sub-bituminous coal, bituminous coal, semi-anthracite, and anthracite in order of increasing carbon content. Compared with anthracite and anthracite (hereinafter referred to as anthracite), the water content is high. Therefore, compared with anthracite and the like, hydrous coal has abundant resources, but its calorific value per unit weight is low, so its energy efficiency as a fuel for transportation costs is low.

  For example, lignite, which is a hydrous coal, has not been used for thermal power generation because it has a high moisture content and is difficult to burn. However, lignite has a wide distribution of reserves, is inexpensive, and easily burns when dried, and has a high calorific value per unit weight, so in recent years it has been used for thermal power generation by drying lignite.

  Therefore, conventionally, in order to dry a hydrated material such as lignite, a fluidized bed drying apparatus that dries while hydrating the hydrated material is used. Further, as a fluidized bed drying apparatus, a fluidized bed comprising a housing part that contains a water-containing substance, and a wind box that is a breathable dispersion plate that is located in the lower part of the housing part and has a plurality of openings in the upper part. A fluidized bed drying apparatus provided with a drying furnace is known (for example, Patent Document 1). In this fluidized bed drying apparatus, fluidized gas such as heated steam is supplied from the wind box into the accommodating portion through the holes of the dispersion plate, so that the water-containing substance accommodated in the drying furnace is dried while flowing.

JP 2011-214816 A

  However, water-containing substances such as lignite are usually dried without being classified after pulverization. Particles formed by pulverization are not uniform in size and have a wide particle size distribution. For this reason, when the superficial velocity of the fluidized gas is low, particles having a small particle size and density and relatively heavy (hereinafter referred to as “heavy particles”) do not flow but sink to the lower part of the drying furnace. Also, when the superficial velocity of the fluidizing gas is high, heavy particles flow and are dried, but relatively light particles having a small particle size and density (hereinafter referred to as “light particles”) are placed in the upper part of the drying furnace. Float and scatter. For this reason, many of the scattered light particles cannot be completely dried.

  Furthermore, since steam is generated by drying the hydrated material, the superficial velocity of the fluidized gas becomes higher toward the upper side of the drying furnace. Therefore, the light particles floating on the upper part of the drying furnace are more likely to be scattered.

  In order to narrow the particle size distribution, for example, it is conceivable that a classifier is provided in the preceding stage of the fluidized bed drying apparatus, and the hydrated substances are classified in advance by the classifier, and each classified hydrated substance is dried by the fluidized bed drying apparatus. However, when a dedicated classifier is newly provided in the fluidized bed drying apparatus, there is a problem that costs are increased.

  Then, in view of such a subject, this invention aims at providing the fluidized bed drying apparatus which can flow and dry the water-containing substance with a wide particle size distribution appropriately by devising the shape of a drying furnace. Yes.

・・・数式（１）

・・・数式（２）
ただし、
Ｑ：流動化ガスの体積流量（ｍ^３／ｓ）
Ｑｇ：乾燥により生成された蒸気の体積流量（ｍ^３／ｓ）
Ａｕ：収容部の上部の横断面の面積（ｍ^２）
Ａｌ：収容部の下部の横断面の面積（ｍ^２）
Ｕｔ：含水物質のうち、相対的に軽い粒子における予め定められた粒子終末速度（ｍ／ｓ）
Ｕｍｆ：含水物質のうち、相対的に重い粒子における予め定められた最小流動化速度（ｍ／ｓ）
In the fluidized bed drying apparatus of the present invention, the area of the upper cross section satisfies the following formula (1), the area of the lower cross section satisfies the following formula (2), and the area of the cross section increases as it moves upward. A fluidized bed drying furnace that includes a gradually increasing storage portion, stores a hydrated substance in the storage part, and forms a fluidized bed by flowing the hydrated substance with a fluidizing gas and dries the hydrated substance, and a bottom of the fluidized bed drying furnace An air box for supplying a fluidized gas from a fluidized bed drying furnace, an introduction part for introducing a hydrated substance into the fluidized bed drying furnace, and a lead-out part for deriving the hydrated substance from the fluidized bed drying furnace. the bottom of the inlet portion side, deriving side bottom than located vertically below the characterized that you have inclined from the bottom side of the inlet side to the bottom side of the lead-out portion side.

... Formula (1)

... Formula (2)
However,
Q: Volume flow rate of fluidized gas (m ³ / s)
Qg: Volume flow rate of vapor generated by drying (m ³ / s)
Au: Area of the cross section of the upper part of the accommodating part (m ² )
Al: Area of the cross section at the bottom of the accommodating part (m ² )
Ut: Predetermined particle end velocity (m / s) of relatively light particles among water-containing materials
Umf: predetermined minimum fluidization speed (m / s) of relatively heavy particles among water-containing materials

  According to the present invention, by devising the shape of the drying furnace, it is possible to appropriately flow and dry a water-containing substance having a wide particle size distribution.

It is a figure for demonstrating the fluidized bed drying apparatus concerning this embodiment. It is a comparison figure for comparing the conventional fluidized-bed drying apparatus and the fluidized-bed drying apparatus of this embodiment. It is a figure for demonstrating the fluidized bed drying apparatus concerning a modification.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. The dimensions, materials, and other specific numerical values shown in the embodiments are merely examples for facilitating the understanding of the invention, and do not limit the present invention unless otherwise specified. In the present specification and drawings, elements having substantially the same function and configuration are denoted by the same reference numerals, and redundant description is omitted, and elements not directly related to the present invention are not illustrated. To do.

  FIG. 1 is a diagram for explaining a fluidized bed drying apparatus 100 according to the present embodiment. The fluidized bed drying apparatus 100 includes a fluidized bed drying furnace 110 and an air box 120. In FIG. 1, the solid flow is indicated by black arrows, and the gas flow is indicated by white arrows.

  The fluidized bed drying furnace 110 includes an accommodating part 112, an introducing part 114, and a leading part 116. The accommodating part 112 is a container for accommodating a hydrated substance such as lignite, and the area of the transverse section (horizontal cross section) of the accommodating part 112 is a funnel shape (conical shape) that gradually increases as it moves above the accommodating part 112. is there. The shape of the accommodating portion 112 will be described later. The water-containing substance is introduced from the introduction part 114 provided on the upper part 112a side of the accommodating part 112, and flows through the accommodating part 112 to form a fluidized bed and is dried, and the outlet part 116 (116a, 116b, 116c). Is derived from The derivation units 116b and 116c are provided with a valve 116d. The hydrated substance is stored in the storage unit 112 by closing the valve 116d, and the hydrated substance is opened from the storage unit 112 through the derivation units 116b and 116c by opening the valve 116d. Is derived. Further, the speed at which the water-containing substance is derived from the deriving units 116b and 116c can be controlled by changing the degree of opening and closing of the valve 116d.

  The wind box 120 is provided below the housing portion 112. The upper part of the air box 120 is formed of a dispersion plate 122 that communicates with the inside of the housing portion 112 and can be ventilated. The wind box 120 allows the vapor (fluidized gas) to flow into the accommodating portion 112 through the openings of the dispersion plate 122. The fluidizing gas causes the water-containing substance to flow in the housing portion 112 to form a fluidized bed and dry the water-containing substance. As the dispersion plate 122, for example, a plate provided with a plurality of apertures having a diameter smaller than the particle size of the water-containing substance to be introduced, or a plate provided with a nozzle provided with the apertures is used.

  The hydrous particles having different particle sizes and densities have different flow characteristics. For this reason, the water-containing substance flows in the accommodating portion 112, so that the particles of the water-containing substance are naturally classified (segregated) according to the difference in particle diameter and density. Therefore, for example, relatively large and heavy particles (hereinafter referred to as “heavy particles”) having a relatively small particle size and density on the lower portion 112b side of the housing portion 112 (hereinafter referred to as “particles having a relatively small particle size and density”). Particles (hereinafter referred to as “medium particles”) whose particle size and density are located in the middle of the particle size distribution on the upper portion 112a side of the accommodating portion 112 are heavy particles and light particles. It will be located in the middle.

  In accordance with the flow characteristics, light particles are led out from the lead-out part 116a provided on the upper part 112a side of the storage part 112, and heavy particles are led out from the lead-out part 116c provided on the lower part 112b side of the storage part 112. Middle particles are derived from a derivation unit 116b provided between the derivation unit 116a and the derivation unit 116c. For this reason, the particle | grains of the particle size and density according to the objective can be isolate | separated.

  When drying a hydrous material with a wide particle size distribution, such as brown coal, if the superficial velocity of the fluidizing gas (the flow rate of steam relative to the cross-sectional area) is low, the heavy particles become difficult to flow and sink, and the fluidizing gas empty When the tower speed is high, the light particles float on the upper portion 112a of the accommodating portion 112 and scatter, so that it cannot be completely dried.

  Further, in the conventional fluidized bed drying apparatus, in the storage unit, the superficial velocity at the top of the storage unit is higher than the superficial velocity at the bottom of the storage unit, and the light particles at the top of the storage unit are more easily scattered. turn into. Here, the superficial velocity inside the accommodating portion in the conventional fluidized bed drying apparatus and the superficial velocity inside the accommodating portion 112 in the fluidized bed drying apparatus 100 of the present embodiment will be described.

  FIG. 2 is a comparison diagram for comparing the conventional fluidized bed drying apparatus 10 and the fluidized bed drying apparatus 100 of the present embodiment. FIG. 2A is a schematic diagram showing a conventional fluidized bed drying apparatus 10, and FIG. 2B is a schematic diagram showing a fluidized bed drying apparatus 100 of the present embodiment. In the figure, the flow of fluidized gas is indicated by white arrows, and the flow of vapor generated by drying is indicated by black arrows. As shown in FIG. 2A, the conventional fluidized bed drying apparatus 10 is configured to include a fluidized bed drying furnace 11 including an accommodating portion 13 and an air box 12.

  As shown in FIG. 2 (a), in the accommodating part 13 of the conventional fluidized bed drying apparatus 10, the cross-sectional area of the upper part 13 a of the accommodating part 13 and the sectional area of the lower part 13 b of the accommodating part 13 are equal. The fluidizing gas flows into the housing part 13 from the wind box 12, and the fluidizing gas moves the water-containing substance and dries while moving toward the upper part 13 a (vertically upward) of the housing part 13. As a result, the water contained in the water-containing substance evaporates, so that steam is newly generated inside the housing portion 13. Such fluidized gas and steam move toward the upper portion 13 a of the accommodating portion 13. For this reason, in the accommodating part 13, the flow rate of the gas (fluidized gas and steam) passing through the same cross-sectional area increases toward the upper part 13a, and the superficial velocity in the upper part 13a of the accommodating part 13 is higher. 13 becomes higher than the superficial velocity in the lower part 13b.

  Therefore, in the present embodiment, as shown in FIG. 2B, the funnel-shaped (conical shape) housing in which the cross-sectional area of the upper portion 112 a of the housing portion 112 is larger than the cross-sectional area of the lower portion 112 b of the housing portion 112. Part 112 is assumed. Then, even if the flow rate of the gas passing through the same cross-sectional area of the upper portion 112a of the housing portion 112 increases, the cross-sectional area of the upper portion 112a of the housing portion 112 is larger than the cross-sectional area of the lower portion 112b of the housing portion 112. It is possible to suppress the increase in gas from being increased by the increase in the cross-sectional area, and to increase the gas superficial velocity. Further, the cross-sectional area of the lower portion 112 b of the housing portion 112 is smaller than the cross-sectional area of the upper portion 112 a of the housing portion 112. For this reason, the superficial velocity of the fluidization gas in the lower part 112b of the accommodating part 112 can be made high, and it can suppress that a heavy particle sinks without flowing.

・・・数式（１）
ここで、Ｑは流動化ガスの体積流量（ｍ^３／ｓ）、Ｑｇは乾燥により生成された蒸気の体積流量（ｍ^３／ｓ）、Ａｕは収容部１１２の上部１１２ａの横断面の面積（ｍ^２）、Ｕｔは軽粒子における予め定められた粒子終末速度（ｍ／ｓ）を示す。 Since light particles are located in the upper part 112a of the accommodating part 112, the superficial velocity of the gas in the upper part 112a of the accommodating part 112 (generated by fluidized gas and drying with respect to the cross-sectional area of the upper part 112a of the accommodating part 112) The vapor flow rate is preferably lower than the superficial velocity at which light particles flow but do not scatter (particle end velocity of light particles). Therefore, the cross-sectional area of the upper part 112a of the accommodating part 112 is calculated | required by following Numerical formula (1) in which a light particle flows, but does not scatter.

... Formula (1)
Here, Q is the volumetric flow rate of fluidized gas (m ³ / s), Qg is the volumetric flow rate of vapor generated by drying (m ³ / s), and Au is the area of the cross section of the upper portion 112a of the accommodating portion 112 ( m ² ), Ut represents a predetermined particle end velocity (m / s) in light particles.

・・・数式（２）
ここで、Ｑは流動化ガスの体積流量（ｍ^３／ｓ）、Ａｌは収容部１１２の下部１１２ｂの横断面の面積（ｍ^２）、Ｕｍｆ：重粒子の最小流動化速度（ｍ／ｓ）を示す。 In addition, since heavy particles are located in the lower portion 112b of the accommodating portion 112, the superficial velocity of the gas in the lower portion 112b of the accommodating portion 112 (flow rate of fluidized gas with respect to the cross-sectional area of the lower portion 112b of the accommodating portion 112). Is preferably higher than the superficial velocity at which heavy particles can flow (the minimum fluidization speed of heavy particles). Therefore, the cross-sectional area of the lower part 112b of the accommodating part 112 is calculated | required by following Numerical formula (2) from which a heavy particle can flow.

... Formula (2)
Here, Q is the volumetric flow rate (m ³ / s) of the fluidizing gas, Al is the cross-sectional area (m ² ) of the lower part 112b of the accommodating part 112, Umf: the minimum fluidization speed of heavy particles (m / s) Indicates.

  With the above configuration, the fluidized bed drying apparatus 100 according to the present embodiment suppresses light particles from scattering at the upper portion 112a of the accommodating portion 112, and prevents heavy particles from sinking without flowing at the lower portion 112b of the accommodating portion 112. Therefore, it is possible to appropriately flow and dry water-containing substances such as lignite having a wide particle size distribution without providing a separate classification device.

  By the way, since heavy particles have a higher water content than light particles, drying may take time. Therefore, in the present embodiment, the residence time of the heavy particles is lengthened by providing an inclination in the bottom portion 118 (dispersion plate 122) of the accommodating portion 112.

As for the bottom part 118 of the accommodating part 112, as shown in FIG. 1, the introducing | transducing part 114 side is located vertically downward from the derivation | leading-out part 116 side, and is inclined from the introducing | transducing part 114 side to the derivation | leading-out part 116 side. When the bottom portion 118 is inclined, a force component in a direction opposite to gravity is required when the heavy particles move from the introduction portion 114 side to the lead-out portion 116 side, so that compared to the case where the bottom portion 118 is horizontal, It becomes difficult to lead out from the lead-out part 116, and the residence time of heavy particles becomes long.

  With the above configuration, the superficial velocity of the fluidized gas can be increased and the residence time of the heavy particles can be increased in the lower portion 112b of the accommodating portion 112, and the heavy particles are derived in a state where they cannot be completely dried. Can be suppressed.

  In order to shorten the residence time of the heavy particles, in the bottom portion 118 of the housing portion 112, the introduction portion 114 side is positioned vertically above the derivation portion 116 side, and is inclined from the introduction portion 114 side to the derivation portion 116 side.

  FIG. 3 is a diagram for explaining a fluidized bed drying apparatus 100 according to a modification. FIG. 3A is a diagram for explaining the fluidized bed drying apparatus 100 according to the first modification, and FIG. 3B is a diagram for explaining the fluidized bed drying apparatus 100 according to the second modification. is there.

(Modification 1)
As shown in FIG. 3A, a heat transfer tube 112 c is provided in the housing portion 112. Steam is supplied to the heat transfer tube 112c from a supply source (not shown), and heat exchange is performed between the heat transfer tube 112c and the water-containing material in the housing portion 112 by the heat of the steam, thereby promoting drying of the water-containing material. it can. Therefore, with the configuration including the heat transfer tube 112c, the fluidized bed drying apparatus 100 according to the modification can further promote the drying of the hydrous material.

(Modification 2)
As shown in FIG.3 (b), in the modification 2, the side wall of the accommodating part 200 of the fluidized bed drying apparatus 100 is stepped. Even in such a configuration, since the cross-sectional area of the upper part 112a of the accommodating part 200 is larger than the cross-sectional area of the lower part 112b of the accommodating part 112, it is possible to appropriately flow and dry a hydrous substance having a wide particle size distribution.

  In the present embodiment, the water containing substance having a wide particle size distribution is appropriately fluidized and dried using the housing part 200 in which the cross-sectional area of the upper part 112a of the housing part 200 is larger than the cross-sectional area of the lower part 112b of the housing part 200. The purpose is that. For this reason, it can implement irrespective of the shape of the side wall of the accommodating part 200. FIG.

  As mentioned above, although preferred embodiment of this invention was described referring an accompanying drawing, it cannot be overemphasized that this invention is not limited to this embodiment. It will be apparent to those skilled in the art that various changes and modifications can be made within the scope of the claims, and these are naturally within the technical scope of the present invention. Is done.

  For example, in the present embodiment, the housing portions 112 and 200 are funnel-shaped, but for example, a polygonal pyramid shape in which the upper cross-sectional area is larger than the lower cross-sectional area may be used. In any case, the upper cross-sectional area only needs to be larger than the lower cross-sectional area.

  Moreover, although this embodiment demonstrated using lignite as a hydrated material, hydrated coal, such as subbituminous coal, can be used.

  Further, in the fluidized bed drying apparatus 100, the three lead-out portions 116 are provided in the accommodating portions 112 and 200. However, the number and positions of the lead-out portions 116 are not limited to such a configuration, and the water-containing substance to be dried segregates. One or more derivation units 116 may be provided in accordance with the above.

  INDUSTRIAL APPLICABILITY The present invention can be used for a fluidized bed drying apparatus that dries while water-containing substances are flowed.

DESCRIPTION OF SYMBOLS 100 Fluidized bed drying apparatus 110 Fluidized bed drying furnace 112, 200 Storage part 112a Upper part 112b Lower part 114 Introducing part 116, 116a, 116b, 116c Outlet part 118 Bottom part 120 Wind box

Claims (1)

The upper cross-sectional area satisfies the following mathematical formula (1), the lower cross-sectional area satisfies the following mathematical formula (2), and includes an accommodating portion whose cross-sectional area gradually increases as it moves upward, A fluidized bed drying furnace for containing a hydrated substance in the section, forming a fluidized bed by flowing the hydrated substance with a fluidized gas, and drying the hydrated substance;
A wind box for supplying the fluidized gas from the bottom of the fluidized bed drying furnace;
An introduction part for introducing the water-containing substance into the fluidized bed drying furnace;
A deriving unit for deriving the water-containing substance from the fluidized bed drying furnace;
Equipped with a,
At the bottom of the fluidized bed drying furnace, the bottom of the inlet portion is positioned vertically below the bottom of the outlet portion side, it is inclined from the bottom side of the introduction portion side to the bottom side of the conductor exit side A fluidized bed drying apparatus.

... Formula (1)

... Formula (2)
However,
Q: Volume flow rate of fluidized gas (m ³ / s)
Qg: Volume flow rate of vapor generated by drying (m ³ / s)
Au: Area of the cross section of the upper part of the accommodating part (m ² )
Al: Area of the cross section at the bottom of the accommodating part (m ² )
Ut: Predetermined particle end velocity (m / s) of relatively light particles among water-containing materials
Umf: predetermined minimum fluidization speed (m / s) of relatively heavy particles among water-containing materials

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