JPH0553560B2 - - Google Patents

Description

Detailed Description of the Invention "Field of Industrial Application" The present invention relates to a multi-stage dryer that is suitably used for drying materials to be dried such as dehydrated sludge cake.
The present invention relates to a multi-stage dryer that can adjust the amount of dried material retained while sufficiently maintaining the stirring operation, which has a large effect on the drying efficiency of the multi-stage dryer.

``Prior Art'' Conventionally, a multi-stage dryer equipped with drying beds arranged in multiple stages has been known as one of the dryers used for drying materials to be dried such as dehydrated sludge cake. . 4 and 5 are diagrams showing examples of conventional multi-stage dryers, and the reference numeral 1 in these figures is
is the main body of the dryer, and 2 is the drying bed.

Inside the dryer main body 1, drying beds 2 are arranged in multiple stages in the vertical direction. Drop openings 3 are formed in some of these drying beds 2. Further, a plurality of rotating shafts 4 are inserted into the dryer main body 1, and a rake 5 is fixed to each of the rotating shafts 4 for each drying bed 2.

The rake 5 rotates as shown by the arrow in FIG. 5 by driving the drive device 6 to rotate each rotating shaft 4, thereby stirring the material to be dried on each drying bed 2. Move it towards the droplet 3,
The device is designed to be dropped from a drop opening 3 onto a lower drying bed 2.

To dry the material to be dried using this multi-stage dryer, combustion exhaust gas is introduced from the inlet 7 provided at the bottom of the dryer main body 1, and the exhaust gas is introduced from the exhaust port provided at the upper part of the dryer main body 1. At the same time, the drive device 6 is driven to rotate each rotating shaft 4. Subsequently, the material to be dried is charged onto the top drying bed 2 from the input port 9 attached to the upper part of the dryer main body 1. The loaded material to be dried is heated by coming into contact with the combustion exhaust gas, and is moved to the drop port 3 of the drying bed 2 by the rotational feeding operation of each rake 5, and from the drop port 3 to the top of the lower drying bed 2. to fall. The material to be dried that has moved sequentially on each drying bed 2 is taken out from the takeout port 10 of the lowest drying bed 2.

``Problem to be solved by the invention'' However, in the conventional multi-stage dryer,
Since it is not possible to adjust the amount of the material to be dried on each drying bed 2, the material to be dried is directly dropped from the drop port 3 by the rotary feeding operation of each rake 5. If each rake 5 is rotated vigorously in order to sufficiently stir the drying material, the material to be dried will move faster, and as a result, the undried material may be discharged or the floor surface may be exposed, reducing the effective drying area. There was a risk of it happening.

In addition, when the amount of material to be dried is large, the thickness of the dried material on the drying bed 2 becomes thick, and the floor surface is no longer exposed, but the amount of feed per revolution of the rake also increases, so the rotation for the purpose of stirring is increased. It cannot be freely adjusted, and as a result, the speed of rotation is restricted. As a result, only the surface of the object to be dried that comes into contact with the combustion exhaust gas becomes a waning rate drying region, which necessitates insufficient stirring. Also, if you try to maintain the thickness of the drying bed when the drying load is low, it is necessary to lower the rotation, resulting in insufficient agitation.On the other hand, if the rotation is accelerated, the bed surface is exposed and the drying area is more likely to be reduced. There was an inconvenience.

The present invention was made in view of the above circumstances, and
By providing sufficient agitation while maintaining the retention amount in the drying bed, it is possible to reduce the degree to which the surface that comes into contact with the heated gas becomes dry at a reduced rate, and to improve the dryness of the material to be dried to, for example, a moisture content of 10% or less. It is an object of the present invention to provide a multi-stage dryer that is capable of performing uniform drying and that is easy to operate in response to fluctuations in the amount and moisture content of materials to be dried.

"Means for Solving the Problem" In order to achieve the above object, the invention according to claim 1 provides the following: drying beds on which objects to be dried are placed in multiple stages in the vertical direction, and the objects to be dried are placed on the drying bed. In a multi-stage dryer provided with a moving mechanism that moves in one direction along a floor surface and drops onto a lower drying bed through a droplet provided downstream in the direction of movement, at least one of the drying beds Each of the drop ports is provided with a retention amount adjusting device for adjusting the amount of the material to be dried on the drying bed provided with the drop port, and each of the moving mechanisms rotates within a plane parallel to the drying bed. A plurality of main rakes are provided along the longitudinal direction of the drying bed, and the retention amount adjusting device includes a sub rake that is provided near the drop port and rotates in a plane parallel to the drying bed. The main rake and the sub rake are driven by separate driving means.

Further, the invention according to claim 2 provides a method of arranging drying beds on which objects to be dried are placed in multiple stages in the vertical direction, and moving the objects to be dried in one direction along the floor surface on the drying bed. In a multi-stage dryer, the dryer is provided with a moving mechanism for causing the drop to drop onto a lower drying bed through a drop port provided downstream of the drying bed, in which the drop port in at least one of the drying beds is provided with a drop port provided on the drying bed. a retention amount adjusting device for adjusting the retention amount of the material to be dried, and the moving mechanism moves a plurality of main rakes, each of which rotates in a plane parallel to the drying bed, along the longitudinal direction of the drying bed. The retention amount adjusting device is configured to include a regulating weir provided near the drop opening so that its height from the drying bed can be adjusted.

"Operation" In the invention described in claim 1, since the main rake and the sub rake are driven by separate drive means, the rotation speeds of the main rake and the sub rake can be adjusted individually. Therefore, by adjusting the rotational speed of the sub rake, the falling amount can be adjusted and the stirring time of the material to be dried on the drying bed can be ensured as long as necessary.

Furthermore, in the invention described in claim 2,
By adjusting the height of the weir, it is possible to adjust the amount of material to be dried near the drop opening and to ensure a longer stirring time in this area as necessary.

"Embodiment" FIGS. 1 and 2 are diagrams showing an embodiment of the invention set forth in claim 1, and reference numeral 11 in these figures indicates a multi-stage dryer.

This multi-stage dryer 11 includes a dryer main body 12, drying beds 13 arranged in multiple stages inside the dryer main body 12, a plurality of rotating shafts 14, and a main rake 15 attached to these rotating shafts 14. and each rotation axis 1
4, a sub rake 19 disposed near the drop port 18 of each drying bed 13, a rotating shaft 20 for rotating this sub rake 19, and a drive device 21. The structure includes a retention amount adjustment mechanism.

A charging device 23 is attached to the upper part of the dryer main body 12 for charging the dryer to be dried into the uppermost drying bed 13 within the dryer main body 12. Further, an inlet 24 for heating gas such as heated steam, heated air, and combustion exhaust gas is provided in the upper part of the dryer main body 12, and an exhaust port 25 is provided in the lower part of the dryer main body 12. ing.

In the stirring/moving mechanism, a plurality of rotating shafts 14 arranged in two rows are rotated by driving a driving device 16, and one rotating shaft 14 is provided for each drying bed 13.
The main rakes 15 fixed to the main rakes 15 are adapted to rotate. By the rotation of these main rakes 15, the material to be dried on each drying bed 13 is sent toward the drop port 18 while being stirred. Also main rake 1
5 are adapted to rotate in synchronization so as not to interfere with each other by interlocking the rotating shaft 14 with a connecting gear (not shown).

The above retention amount adjustment mechanism rotates the sub rake 19 disposed near the drop port 18 of each drying bed 13 by driving the drive device 21 and rotating the rotating shaft 20, thereby causing the main rake 15 to rotate. A part or all of the material to be dried thus sent is allowed to fall from a drop opening 18 onto a lower drying bed 13.

The amount of material to be dried falling from the drop port 18 can be adjusted by the rotation speed of the sub rake 19.
Further, the rotation speed of the sub rake 15 can be set independently of the rotation speed of the main rake 15.

In order to dry the material to be dried using the multi-stage dryer 11 configured as described above, first, the inlet 24
Heating gas such as heated steam is introduced into the dryer main body 12 from the dryer main body 12, and the driving device 16 of the stirring/moving mechanism and the driving device 21 of the retention amount adjusting mechanism 22 are respectively driven.

Subsequently, from the feeding device 23 to the top drying bed 13
Put the material to be dried into the container. The input material to be dried is
While being agitated by the rotation of the main rake 15, it is sent toward the drop port 18 and reaches the sub rake 19.

The material to be dried that has reached the sub-rake 19 is transferred to the sub-rake 1.
9, it falls from the drop opening 18 onto the lower drying bed 13. At this time, if the conveyance amount of the sub rake 19 is set smaller than the conveyance amount of the main rake 15, the amount of the material to be dried increases in the drying bed 13, and the main rake 15 transfers the material to the sub rake 19. The material to be dried that has been sent and accumulated returns to the main rake 15 again,
The main rake 15 is used to stir the dried material, so that the material to be dried can be sufficiently stirred.

The material to be dried in the drying bed 13 is sufficiently stirred by the main rake 15 and at the same time
It is heated by contact with the heated gas introduced into the container, and the moisture contained therein is evaporated and dried. At this time, since the material to be dried is sufficiently agitated by the main rake 15, the material to be dried becomes lumpy due to insufficient stirring, and the surface area becomes a decreasing rate drying region, which changes the degree of dryness of the material to be dried. Drying is carried out in a uniform state without the inconvenience of unevenness.

A part of the material to be dried transported to the sub-rake 19 is
It is dropped and conveyed from the drop port 18 to the lower drying bed 13. When the rotation of the sub rake 19 is slowed down to reduce the conveyance amount, the thickness of the dried material on each drying bed 13 increases, and when the rotation is accelerated, the thickness of the dried material becomes thinner.

The objects to be dried that have fallen from the drop opening 18 onto the lower drying bed 13 are further lowered one after another by the same conveyance operation, are brought into contact with the heating gas, are heated, and are further dried. Then, the dried material is taken out from the dryer main body 12 through the droplet 18 of the drying bed 13 at the lowest stage.

This multi-stage dryer 11 is configured as described above, and by adjusting the amount of drying material to be dropped from the opening of each drying bed to the lower drying bed, the moving mechanism moves the material to be dried. Sufficient stirring can be performed.

In addition, since the amount of material to be dried in each drying bed can be adjusted arbitrarily for each stage using a retention amount adjustment mechanism, it is possible to adjust the amount of material to be dried in each drying bed, depending on changes in the amount of material to be dried, moisture content, or the properties of the material as drying progresses. It is possible to easily respond to changes in driving.

In the previous example, the heated gas such as heated steam was flowed in parallel with the flow of the material to be dried, but the heated gas may also be flowed countercurrently.

In addition, in the previous example, there is one sub rake for each drying bed 13.
Although the number of sub-rakes 19 is not limited to this, the sub-rakes 19 may be provided on at least one of the drying beds 13.

Experimental Example 1 Sewage sludge (dehydrated cake) that had been dehydrated was dried using a multistage dryer having the same configuration as that shown in FIGS. 1 to 3.

The multi-stage dryer has 5 drying beds, the total area of the drying bed is 50 m ² , the main rake rotates 5 times per minute, the main rake transports 50 dry materials per minute, and the sub rake transports 50 per minute. min 10, heating steam (as heating gas)
The temperature was set at 300°C and the amount of heated steam introduced was set at 50 m ³ per minute, and a dehydrated cake with a moisture content of 80% was placed in this multistage dryer and dried. As a result, a powdery dried product with a water content of 10% or less and almost no variation in dryness was obtained. Furthermore, as a result of examining the combustibility of the obtained dried product, it was found that the dried product exhibited good combustibility and produced a calorific value comparable to that of low-rank coal.

On the other hand, for comparison, a dehydrated cake was dried under the same conditions as above using a multi-stage dryer having a configuration in which the sub-rake of the multi-stage dryer was removed. As a result, the dried product obtained has a moisture content of
The drying state was non-uniform, with a mixture of dry matter ranging from lumps of about 50% to powdery dry matter with moisture content close to 0%.

Next, an embodiment of the invention set forth in claim 2 will be described.

FIG. 3 is a diagram showing an embodiment of the invention set forth in claim 2.

The multi-stage dryer according to this example has an adjustment weir 26 at the drop port 18 of each drying bed 13, instead of the retention amount adjustment mechanism 22 in the multi-stage dryer 11 according to the previous example.
27. In this figure, the same components as those shown in FIGS. 1 and 2 are designated by the same reference numerals, and their explanations will be omitted.

As the above-mentioned adjustment weirs 26 and 27, fixed types and movable types are provided. Among these, the fixed adjustment weir 26 is preferably the main rake 15
The thickness of the material to be dried in the drying bed 13 on which the adjustment weir 26 is installed is set to be at least the height of the main rake, and the amount of retention in the drying bed 13 is maintained at a constant level. This prevents the drying bed 13 from being exposed during the stirring operation by the main rake 15. Further, it is preferable that the adjusting weir 26 be of a replaceable type, so that the height of the weir can be arbitrarily adjusted by replacing the adjusting weir 26 from the outside of the dryer main body 12 to a desired weir height.

In addition, the movable adjustment weir 27 is connected to the dryer main body 12.
By moving a lever 28 provided on the outside in the direction of the arrow in the figure, the substantial height of the adjustment weir 27 can be varied to some extent. In this adjustment weir 27, the thickness of the material to be dried in the drying bed 13 can be arbitrarily adjusted, so that the amount of staying material can be easily adjusted in response to fluctuations in the amount of material to be dried and the moisture content.

In order to dry the material to be dried using the multi-stage dryer 11 configured as described above, first, the inlet 24
Heated gas such as heated steam, heated air, and combustion exhaust gas is introduced into the dryer main body 12 from the dryer body 12, and the drive device 16 of the stirring/moving mechanism is driven.

Subsequently, from the feeding device 23 to the top drying bed 13
Put the material to be dried into the container. The input material to be dried is
While being stirred by the rotation of the main rake 15, it is sent toward the drop port 18, and is sent to the adjustment weirs 26, 2.
It is stopped by 7. As a result, drying bed 1
The amount of the material to be dried in the main rake 15 increases, and the remaining material to be dried is stirred by the main rake 15 again. The material to be dried in the drying bed 13 is transported to the main rake 1
At the same time, the dryer is sufficiently stirred by the dryer main body 12 and heated by contacting the heated gas introduced into the dryer main body 12 to evaporate the moisture contained therein and dry it. At this time, since the material to be dried is sufficiently agitated by the main rake 15, the material to be dried becomes lumpy due to insufficient stirring, and the surface area becomes a decreasing rate drying region, which changes the degree of dryness of the material to be dried. Drying is carried out in a uniform state without the inconvenience of unevenness.

The material to be dried, which has crossed the control weirs 26 and 27 and fallen from the drop port 18 onto the lower drying bed 13, is further successively lowered through each drying bed 13 by the same conveyance operation, and comes into contact with the heated gas. The drying bed 1 is heated and dried by evaporating moisture.
It is taken out from the dryer main body 12 through the drop port 18 of No. 3.

This multi-stage dryer 11 is configured as described above, so that the material to be dried sent by the main rake 15 is dammed up by the regulating weirs 26 and 27 disposed at the drop opening 18 of the drying bed 13, and each The amount of the material to be dried on the drying bed 13 can be adjusted, and the main rake 15 can sufficiently stir the material to be dried.

In addition, the height of the adjustment weir 26 can be set in advance to a predetermined height according to the amount of material to be dried and the amount of moisture, or the height of the weir can be adjusted during drying using the movable adjustment weir 27. Since the amount of material to be dried on the bed 13 can be adjusted, it is possible to easily respond to changes in the amount of material to be dried and moisture content.

In addition, in the previous example, the amount of retention in each drying bed was adjusted using either a fixed regulating weir or a movable regulating weir, but the combination of regulating weirs is particularly limited. Any structure may be used as long as a movable or replaceable regulating weir is provided at the drop of at least one drying bed to adjust the amount of retention in the drying bed.

Experimental Example 2 Sludge (dehydrated cake) that has been dehydrated using a multi-stage dryer with the same configuration as the one shown in Figure 3
A drying process was performed.

The multi-stage dryer has 5 drying beds, a total drying bed area of 50 m ² , and a fixed regulating weir (located at the opening of each drying bed in the 1st, 2nd, 4th, and 5th stages). ) weir height
200mm, movable regulating weir (placed on the third drying bed)
The weir height is 0 to 300 mm, the main rake blade height is 100 mm, the main rake rotation speed is 5 times per minute, the temperature of heated steam (as heated gas) is 300°C, and the heated steam introduction rate is 50 times per minute.
^m3 , and a dehydrated cake with a water content of 80% was placed in this multi-stage dryer and dried.

As a result, a powdery dried product with a water content of 10% or less and almost no variation in dryness was obtained.
Furthermore, as a result of examining the combustibility of the obtained dry product, it was found that the obtained dry product exhibited good combustibility and produced a calorific value comparable to that of low-rank coal.

"Effects of the Invention" As explained above, in the invention described in claim 1, since the main rake and the sub rake are driven by separate drive means, the rotational speed of the main rake and the sub rake can be adjusted individually. can be adjusted to Therefore, by adjusting the rotation speed of the auxiliary rake installed near the drop opening, the amount of material falling from the upper drying bed to the lower drying bed can be adjusted, and the stirring time of the material to be dried on the drying bed can be adjusted. This agitation can be maintained for a long time as needed, and by this stirring, it is possible to obtain uniform and sufficient dryness, and it is possible to easily perform optimal operation in response to changes in the composition of the material to be dried. I can do it.

Furthermore, in the invention described in claim 2,
By adjusting the height of the weir, the height of the material to be dried near the droplet can be adjusted, and the stirring time in this area can be secured as long as necessary, similar to the case of claim 1. Even and sufficient drying can be achieved.

[Brief explanation of the drawing]

1 and 2 are views showing an embodiment of the invention as claimed in claim 1, in which FIG. 1 is a perspective view of the main parts of a multi-stage dryer, and FIG. 2 is a main part of the multi-stage dryer. FIG. 3 is a perspective view of essential parts of a multi-stage dryer showing an embodiment of the invention as claimed in claim 2, and FIGS. 4 and 5 are views showing a conventional multi-stage dryer. FIG. 4 is a longitudinal cross-sectional view of the multi-stage dryer,
FIG. 5 is a sectional view taken along the line B--B in FIG. 4. 11...Multi-stage dryer, 13...Drying bed, 17...
... Stirring/moving mechanism (moving mechanism), 18... Drop port, 22... Retention amount adjustment mechanism, 26, 27... Adjustment weir.

Claims (1)

[Scope of Claims] 1. By arranging drying beds on which objects to be dried are placed in multiple stages in the vertical direction, and moving the objects to be dried in one direction along the floor surface on the drying bed, In a multi-stage dryer provided with a moving mechanism for dropping the material onto a lower drying bed through a droplet provided in at least one of the drying beds, the coating on the drying bed provided with the droplet is provided at the droplet in at least one of the drying beds. A retention amount adjusting device for adjusting the retention amount of dry matter is provided, and the moving mechanism includes a plurality of main rakes provided along the longitudinal direction of the drying bed, each of which rotates in a plane parallel to the drying bed. The retention amount adjusting device includes a sub rake that is provided near the drop port and rotates in a plane parallel to the drying bed, and the main rake and the sub rake are driven by separate driving means. A multi-stage dryer characterized by: 2. By arranging drying beds on which items to be dried are placed in multiple stages in the vertical direction and moving the items to be dried in one direction along the floor surface on the drying bed, a droplet provided downstream in the direction of movement is created. In a multi-stage dryer provided with a moving mechanism for dropping materials to a lower drying bed through a droplet, an amount of the material to be dried accumulated on the drying bed provided with the droplet is set at a droplet in at least one of the drying beds. a retention amount adjusting device for adjusting the retention amount; the moving mechanism includes a plurality of main rakes each rotating in a plane parallel to the drying bed along the longitudinal direction of the drying bed; A multi-stage dryer characterized in that the apparatus comprises an adjustment weir provided near the drop port so that its height above the drying bed can be adjusted. 3. The multi-stage dryer according to claim 2, wherein the retention amount adjusting device is a replaceable regulating weir. 4. The multi-stage dryer according to claim 2, wherein the retention amount adjusting device is a movable regulating weir.