JPH0437355B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a fluidized bed dryer having a group of rotating heating tubes.

[Conventional technology] Fluidized bed technology is used to dry powder, heat exchange, calcination,
Furthermore, it is widely used for waste incineration, thermal decomposition, etc., because it has excellent heat transfer properties and is easy to handle and process powder and granules.

Fluidized bed technology is also used for drying, but usually the granular material to be dried is fluidized by heated air and the drying operation is performed using the heat.

On the other hand, as a special fluidized bed dryer,
As described in Japanese Patent No. 26516, it is known that a heating wall in which heating tubes are arranged is installed in a fluidized bed section. According to the publication, the main improvement is the drying efficiency.

[Problems to be Solved by the Invention] However, if the target wet powder tends to adhere to the heating tube, this poses a major operational problem. That is,
As shown in Fig. 4, when heating tubes P are arranged horizontally, heating air A is biased and does not reach the upper part of the tubes P, which becomes a cloud of wet powder, and the heating tubes P
A fixed body S is formed on the top of the . This reduces the effective area for indirect heating and gradually reduces the efficiency of the dryer. In addition, the powder and granules stuck to the heating tube P are exposed to high temperatures for a long period of time, so they change in quality, and if they peel off, this results in the contamination of the product with impurities. Therefore, an object of the present invention is not only to prevent such deterioration of the drying effect, but also to dramatically improve the drying efficiency, and also to prevent deterioration of the quality of the material to be dried.

[Means for Solving the Problems] In order to solve the above-mentioned problems, the present invention provides a system in which a heating medium passes within a height range of a fluidized bed in which powder and granules to be dried are fluidized by a fluidized bed gas. All heating tube groups consisting of a plurality of tubes are arranged substantially horizontally and in parallel, and the heating tube groups are rotatable around a common rotation center line in each group. The structure is such that the entire fluidized bed is uniformly stirred as the group rotates.

The present invention is fundamentally different from the technique described in the above-mentioned publication in that the heating tube group is rotated around a common rotation center line. In the prior art, the heating tube is left stationary.

[Operation] According to the present invention, as shown in FIGS. 1 and 2, a group of heating tubes rotates around a rotation center line passing through the rotation axes 2 and 3. Therefore, if one heating tube 1 is taken and considered, the top point when it is at the top position changes its position sequentially as it rotates, and when the heating tube 1 is at the bottom position, the top point is the top point when it is at the top position. Also facing the bottom. Therefore, the entire circumferential surface of the heating tube is evenly exposed to the flowing gas (usually air),
There is no dead center caused by the flowing gas as in the conventional case.
As a result, there is no sticking of the material to be dried, and it is possible to dry materials that could not be treated with conventional devices.

On the other hand, due to the rotation of the heating tube group, the material to be dried is not only fluidized by the fluidizing gas but also given a stirring force. As a result, the entire fluidized bed is uniformly fluidized and stirred, resulting in a dryer with a high heat transfer coefficient. By stirring the powder, the amount of flowing air (wind speed) is reduced, and the power of the chest cavity blower and exhaust gas exhaust fan can be reduced, and exhaust heat loss can be minimized. It can be suppressed.

[Specific Examples of the Invention] Next, the present invention will be explained using specific examples shown in the drawings.

(Structure) FIGS. 1 and 2 are examples of a single heating tube group built-in type, in which one group of heating tubes is built into the casing 4. Each heating tube 1 is supported by end plates 5,6. The end plates 5 and 6 are held by a central beam 7 and are fixed to left and right mirror plates 8 and 9.
The end plates 8 and 9 are integrated with the hollow rotating shafts 2 and 3, respectively. 10 is a reinforcing plate.

Both ends of the heating tube 1 are open to an inflow chamber 11 and an outflow chamber 12 for a heat medium, such as steam, which are constituted by end plates 5, 6 and end plates 8, 9, respectively.

The rotating shaft 2 is supported by a bearing 14 provided on a bracket 13 attached to the casing 4, and a rotary joint 15 is provided at the end thereof, into which an inlet 16 for the heat medium St is provided.
is formed. On the other hand, the rotating shaft 3 is supported by a bearing 18 provided on a blanket 17, and a rotary joint 19 is provided at the end thereof.
is provided, and an outlet 20 for the drain Dr is formed there. Furthermore, a driven gear 21 is fixed to the rotating shaft 3 and is continuous with an output shaft of a rotational drive motor (not shown). 22 is a shaft seal between the rotating shafts 2 and 3 and the casing 4.

A dispersion plate 23 is provided above the bottom plate of the casing 4, and the space surrounded by this is divided into 16 rooms (4 in the longitudinal direction, 4 in the circumferential direction, 4 in the circumferential direction,
It is divided into a total of 16 rooms), each forming an air supply (plenum) room. A flowing gas, for example heated air A, is supplied to each air supply chamber.

In the upper part of the casing 4, there is a supply port 2 for the material to be dried M.
5 and an exhaust port 26 are formed. Also 2
7 is a mounting port for the dried material M'. 28 is a drain pipe. Note that 29 is an auxiliary stirring blade, which is fixed to the mirror plates 5, 6 and the reinforcing plate 10 via a mounting plate 30. The auxiliary stirring blade 29 further enhances the stirring effect. Note that the stirring blades do not have to be installed completely radially as shown in the figure, but may be installed diagonally (with the direction along the blades not facing the center), or the blades themselves can be installed in a way that increases the raking effect. It may be bent into a shovel shape for this purpose. moreover,
A plurality of them may be provided in the longitudinal direction (axial direction).

(Function) In the device configured as described above, the powder or granular material to be dried, which is introduced into the casing 4, is fluidized by the heated air blown up through the holes in the dispersion plate 23. , drying is achieved by the heat. On the other hand, the heated steam St passes through each heating tube 1 from the inlet 16, gives heat to the powder and granules,
It becomes a drain and accumulates at the bottom of the outflow chamber 12,
It is discharged through drain pipe 28. Therefore, the granular material is indirectly heated by the heating tube 1 and dried. At the same time, since rotational force is applied to the rotating shaft 3 via the driven gear 21, each group of heating tubes is rotated around the rotation center line (a line passing through the rotating shafts 2 and 3), and the fluidized powder is rotated. Stir. Exhaust gas associated with drying is discharged from the exhaust port 26, and product is discharged from the outlet 27.
is discharged from.

(Other specific examples) FIG. 3 is an example in which a plurality of heating tube groups are provided. The structure is clear from the drawings, so it will not be described in detail.

[Example] The apparatus shown in FIGS. 1 and 2 was manufactured and its drying ability was investigated.

The external shape is set so that it fits within a circle with a diameter of 950 mm inside a casing with a width of 1 m, a length of 4 m, and a height of 2.4 m.
80 50.1mm heating tubes are arranged horizontally, heat transfer area is ^50m2
And so. The heating tube group was rotated at a speed of 10 RPM by a 5.5 KW electric motor with a speed reducer. Heated air at 150°C was blown up from the bottom at a rate of 200 m ³ /min, and steam at a pressure of 5 kg/m ² was supplied to the heating tube group.

Then, the by-product jam from the cornstarch production factory was fed into the steam dryer at a rate of 5000 kg/hr.
The one with an inlet moisture content of 50% was dried to 5%. The air outlet temperature at this time was 70°C.

From this result, compared to the conventionally used steam tube dryer (indirectly heated rotary dryer) with a heat transfer area of 350 m ² , diameter of 1.8 m, and length of 15 m, equipment costs are 40% lower. The drying capacity increased by approximately 25%.

[Effects of the Invention] As described above, since the heating tube group of the present invention is rotated, it is possible to reliably prevent the objects to be dried from adhering to the heating tubes, and to effectively use the entire circumferential surface for drying. Moreover, since stirring power is also applied, fresh and uniform contact with the powder or granules is always achieved, the drying ability is improved, and furthermore, power costs and exhaust heat loss can be prevented, among other advantages.

[Brief explanation of drawings]

FIG. 1 is a sectional view of an example of the device of the present invention, FIG. 2 is a view taken along the - line, FIG. 3 is a sectional view of another example, and FIG.
The figure is an explanatory diagram of the manner in which dried matter adheres to a conventional stationary heating tube. 1... Heating tube, 2, 3... Rotating shaft, M... Material to be dried, M'... Product, St... Heating steam, Dr... Drain, A... Heating air.

Claims (1)

[Claims] 1. A group of heating tubes consisting of a plurality of tubes through which a heating medium passes are arranged substantially horizontally and in parallel within the height range of the fluidized bed where the powder to be dried is fluidized by the fluidized bed gas,
The group of heating tubes is rotatable around a common rotation center line in each group, and the powder and granular material to be dried is fluidized and the entire fluidized bed is uniformly agitated as the group of heating tubes rotates. Fluidized bed dryer.