JPH10170151A - Continuous dryer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To facilitate a stable treatment of a large amount of material to be treated such as a sewage sludge in a short period with a continuous dryer which dries the material to be treated during the transfer thereof and continuously discharges the sewage sludge, by a method wherein the continuous dryer defines a transfer passage of the material to be treated by connecting a plurality of barrels in which screw conveyors are respectively mounted with a plurality of agitating chambers in which agitating means are respectively mounted. SOLUTION: Four barrels 3-6 which are respectively provided with screw conveyors 15-18 therein are connected in series with a plurality of agitating chambers 7-10 which are respectively provided with agitating blades 27-30 and crushers 35-38. The uppermost barrel 3 has an inlet thereof connected with a hopper 1 by way of a screw feeder 2 and the rotational speed of the screw feeder 2 is changed so as to regulate a supply amount of sludge. A plurality of heaters 11-14 are respectively mounted on the outer peripheries of the barrels 3-6, while a plurality of heaters 23-26 are respectively mounted on the outer peripheries of the agitating chambers 7-10. The agitating chambers 7-10 are also provided with air discharge outlets 39-42 respectively and these air discharge outlets 39-42 are connected with a vacuum pump 43. Due to such a construction, the sludge is heated while being transferred through respective barrels 3-6 and is dried gradually.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a process for continuously receiving an object to be treated containing a large amount of water, such as sewage sludge,
The present invention relates to a continuous drying device that gradually dries while being transferred through the device and continuously discharges the dried product.

[0002]

2. Description of the Related Art Conventionally, in a continuous drying apparatus for continuously drying and discharging sludge containing a large amount of water such as sewage sludge, it is not always easy to increase the processing capacity per unit time. Was.

[0003] That is, when sludge containing a large amount of water is transferred using a screw conveyor, the sludge aggregates in the barrel to form a lump, which may clog the barrel.
Therefore, in the case of continuous treatment of sludge, not only the throughput per unit time is limited, but also in order to continuously transfer without clogging the transfer path, the water must be reduced to a predetermined level or less at the initial stage. And there is a problem that energy consumption required for drying increases.

For this reason, when processing a large number of objects to be processed, it is inevitable to adopt a batch drying method, and use a large-capacity drying cylinder into which a large amount of objects to be processed can be charged at once. Had been drying for a long time. But,
Batch type drying equipment has various problems such as large size of the whole equipment, long time required for drying, difficulty of automation due to batch type, and environmental problems such as dust when charging and discharging. I was having.

[0005]

SUMMARY OF THE INVENTION It is an object of the present invention to replace a batch type drying apparatus having the above-mentioned problems with a continuous and energy-efficient continuous apparatus which is relatively easy to compact and automate. It is an object of the present invention to provide a continuous drying apparatus capable of stably processing a large amount of processing objects in a short time by improving the drying apparatus.

[0006]

SUMMARY OF THE INVENTION A continuous drying apparatus according to the present invention is a continuous drying apparatus which gradually dries an input object to be processed while transferring the inside of the apparatus and continuously discharges the object. The transfer path of the object is characterized in that a plurality of stages are alternately connected to a cylindrical barrel having a screw conveyor therein and a stirring chamber having stirring means therein.

In the continuous drying apparatus of the present invention, the transfer path is constituted by alternately connecting a cylindrical barrel and a stirring chamber in a plurality of stages. In this way, by inserting a plurality of stirring chambers in the middle of the transfer path, stirring and drying of the processing target can be efficiently performed. As a result, agglomeration of the processing object in the barrel can be prevented, so that a large amount of the processing object can be dried continuously and stably.

[0008] Preferably, the stirring chamber is formed of a cylindrical member having a diameter larger than that of the barrel and having an axis parallel to an axial direction of the barrel. This makes it possible to ensure a smooth flow of the object to be processed and to design the entire apparatus compact.

[0009] Preferably, one end of the screw conveyor arranged in the casing is extended to the inside of a stirring chamber arranged on the upstream side of the casing. This makes it possible to reliably send out the object to be processed inside the stirring chamber to the barrel on the downstream side.

Preferably, crushing means is provided in at least one of the stirring chambers. As a result, the lump of the processing object formed by agglomeration during the transfer by the screw conveyor is crushed, and the occurrence of clogging in the transfer path is prevented beforehand, and long-time continuous operation is ensured.

Incidentally, the crushing means can be driven by the same drive shaft as the stirring means provided inside the drying chamber. Preferably, a vacuum exhaust means is connected to at least one of the drying chambers. Thereby, the steam and the like generated inside the device can be quickly discharged to the outside of the device, and the drying efficiency can be improved.

[0012] Preferably, when a vacuum exhaust means is connected to at least one of the drying chambers,
An opening for opening the inside of the drying chamber to the atmosphere is provided, and a valve whose opening can be adjusted is attached to the opening. This makes it possible to adjust the flow of air, water vapor, and the like inside the drying chamber, thereby improving the drying efficiency.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows an outline of a continuous drying apparatus according to the present invention. In the figure, 1 is a hopper, 3
-6 are barrels, 7-10 are stirring chambers, 15-18 are screw conveyors, 27-30 are stirring blades (stirring means), 35
38 to 38 are crushers (crushing means), 23 to 26 are heaters, 3
9 to 42 are exhaust ports, 44 to 47 are intake ports, and 43 is a vacuum pump (decompression exhaust means) for decompression and exhaustion.

In this continuous drying apparatus, four barrels 3 to 6 each having a horizontal axis are vertically stacked in four stages, and the barrels are connected in series via stirring chambers 7 to 10. It is configured. Screw conveyors 15 to 18 are provided inside the barrels 3 to 6, respectively. In each of the stirring chambers 7 to 10, stirring blades 27 to 30 and a crusher 35 are provided.
To 38 are provided. The screw conveyor 15
Driven by a motor 19 attached to the end of the barrel 3, the screw conveyors 16 to 18 are driven by motors 20 to 22 attached to the end of the stirring chamber, respectively. Each of the crushers 35 to 38 respectively has a stirring blade 27 to
30 are driven by the same drive shaft, and each drive shaft is provided with a motor 31-34 attached to the end of each drying chamber.
Driven by

A hopper 1 is connected via a screw feeder 2 to the inlet of the barrel 3 on the most upstream side (uppermost stage). By changing the rotation speed of the screw feeder 2, the supply amount of sludge can be arbitrarily adjusted. Around each of the barrels 3 to 6, a heater 11 is provided.
~ 14 are attached, and around each of the stirring chambers 7 ~ 10,
Each of the heaters 23 to 26 is attached.

Each of the stirring chambers 7 to 10 has an exhaust port 3
9 to 42, and these exhaust ports are connected to a vacuum pump 43. Further, each of the stirring chambers 7 to 10 is
The intake ports 44 to 47 are provided, and these intake ports are opened to the atmosphere via valves 48 to 51 whose opening can be adjusted.

FIG. 2 is a sectional view taken along the line AA of FIG. The stirring chamber 7 has a cylindrical shape having a horizontal axis.
A barrel 3 is connected near the upper end of the end, and a barrel 4 is connected near the lower end. Inside the stirring chamber 7, a biaxial crusher 35 and a pair of stirring blades 27 are arranged. In this example, the crusher 35 and the stirring blade 27 are driven by a common pair of drive shafts.

Next, the function of the continuous drying apparatus will be described. The sludge supplied from the hopper 1 is sent to the uppermost barrel 3 with the supply amount adjusted by the screw feeder 2. While the sludge is being transported through the barrel 3 by the screw conveyer 15, the sludge is heated by the heater 11 disposed around the sludge, and is gradually dried.

The sludge that has passed through the inside of the barrel 3 and has reached the stirring chamber 7 falls on the rotating teeth of the two-shaft crusher 35 which mesh with each other and is crushed. Is done. The inside of the stirring chamber 7 is depressurized by the vacuum pump 43, so that evaporation of moisture and the like is promoted, and further drying proceeds. In this manner, by crushing the sludge mass, the surface area of the sludge increases, and the inside of the sludge is exposed to the drying atmosphere, so that the drying efficiency is improved.

The sludge that has reached the bottom of the stirring chamber 7 is sent into the second barrel 4 by the screw conveyor 16. Similarly, the subsequent barrels 4 to 6 and the stirring chambers 8 to 1
Even at 0, drying, crushing and stirring are performed.

As described above, the agitation chambers are arranged at a plurality of places in the middle of the sludge transfer path, and the stirring blades and the crusher are provided therein. To prevent clogging of the device and increase the efficiency of drying.

In this embodiment, the vacuum chamber 43 is evacuated and evacuated while the interiors of the stirring chambers 7 to 10 are opened to the atmosphere via valves 48 to 51 whose opening can be adjusted. . By forming a forced air flow inside the stirring chamber in this way, the steam generated from the sludge can be efficiently discharged from the stirring chamber, and the drying efficiency can be further improved. An operation method of the drying apparatus will be described.

First, only the screw conveyor 15 and the stirring blade 27 on the most upstream side (uppermost stage) are rotated, and the stirring chamber 7 is rotated.
To store sludge. When a predetermined amount of sludge is stored, the screw conveyor 19 and the stirring blade 28 at the next stage are also rotated to store a predetermined amount of sludge in the stirring chamber 8. After a predetermined amount of sludge is stored in all the stirring chambers by the same procedure, continuous operation is started.

During continuous operation, the screw conveyor 15 ~
As the transfer speed by 18, two speeds of a large-capacity transfer operation mode and a small-capacity transfer operation mode are set, and the large-capacity transfer operation mode and the small-capacity transfer operation mode are set as follows.
Continuous operation is performed while switching alternately periodically. The stirring blades 27 to 30 in the stirring chambers 7 to 10 operate at a constant rotation speed regardless of these operation modes.

The operation in the small-volume transfer operation mode is performed in the stirring chamber 7.
Screw conveyors 16 to 18, 5
Since part 2 performs the auxiliary function of stirring, it is rotated at 1/10 to 1/20 of the rated maximum speed. The number of revolutions in the high-volume transfer operation mode is automatically determined by the required drying capacity.

That is, the number of rotations in the large-capacity transfer operation mode is n
₁ , the transfer amount at this time is Q ₁ , the rotation speed in the small-capacity transfer operation mode is n ₂ , the transfer amount at this time is Q _2, and the operation time ratio of both operation modes is m ₁ / m _2. The average transfer quantity Q

[0027]

(Equation 1) Since the rotation speed and the transfer amount are proportional to the rotation speed in the usage range,

[0028]

(Equation 2) Therefore, assuming that the transfer capacity at the rated maximum rotation speed N is Qmax, the rotation speed in the large-capacity transfer operation mode is n ₁

[0029]

(Equation 3) And the required drying capacity Q, the operation time ratio m ₁ / m ₂ in both operation modes, and the rotation speed n in the small capacity transfer operation mode
_The value is automatically determined by ₂ .

At this time, the amount of sludge to be supplied into the barrel 3 via the screw feeder 2 is set to an amount slightly lower than the transfer capacity of the screw conveyors 15 to 18, and each of the stirring chambers 7 to 10 is set. Has a volume of 30-7
Operate so that about 0% of sludge is stored. In the case of the large-capacity transfer operation mode, the sludge transferred to the stirring chamber is not sufficiently dried. If the sludge that has not been sufficiently dried is transferred at a high rotation speed, it tends to solidify in the inside of the barrel, and if the operation is continued for a long time, the barrel may be blocked.

Therefore, the operation mode is periodically switched to the small-capacity transfer operation mode. In the small-capacity transfer operation mode, the amount of supply by the screw feeder 2 is reduced, and at the same time, each of the screw conveyors 15 to 18 is operated at a lower rotation speed than its rated capacity. In this operation mode, compared with the sludge treatment speed (transfer speed), in particular, sludge drying, crushing, and stirring capacity in the stirring chamber have a margin, so that problems such as sludge aggregation or blockage of the transfer path due to the sludge flocculation. However, the sludge clumps generated by coagulation in the preceding large-capacity transfer operation mode can be eliminated.

The present invention is not limited to the above example,
Various modifications are possible. For example, in the above example, a heater is used as a heating means for the barrel and the stirring chamber, but a method of circulating hot air controlled to a predetermined temperature may be used. Although the two-shaft crusher and the stirring blade are driven using a common drive shaft, separate motors and drive shafts may be provided. Further, it is not necessary to provide crushing means in all the stirring chambers. A vacuum pump for depressurizing and exhausting the inside of the stirring chamber, a valve with an adjustable opening attached to the opening, and the like may be provided as needed. Further, in the above example, the operation is performed by periodically and alternately switching between the large-capacity transfer operation mode and the small-capacity transfer operation mode. However, the operation mode is switched at any time by monitoring the internal state of the apparatus. You may. For example, the load of the screw conveyor can be monitored, and the mode can be switched to the small capacity transfer operation mode when the load exceeds a predetermined value.

[0033]

In the continuous drying apparatus according to the present invention, the stirring chambers are arranged at a plurality of places along the transfer route of the object to be treated (sludge, etc.), and the stirring blades and the crusher are provided therein. Since the agglomeration of the object to be treated that has been agglomerated during the transfer in the inside is crushed, blockage of the apparatus is prevented, drying efficiency is high, and a large amount of sludge can be continuously treated. Therefore, a compact continuous drying apparatus that is excellent in energy efficiency, capable of large-scale processing, and is realized.

Further, by alternately switching between the large capacity transfer operation mode and the small capacity transfer operation mode for operation,
The throughput can be further increased without the risk of blockage of the device.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram showing an example of a continuous drying apparatus according to the present invention.

FIG. 2 is a sectional view of the continuous drying apparatus taken along line AA of FIG. 1;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Hopper 2 ... Screw feeder, 3, 4, 5, 6 ... Barrel, 7, 8, 9, 10 ... Stirring chamber, 11, 12, 13, 14 ... Heater (Barrel) 15, 16, 17, 18 ... screw conveyor, 23, 24, 25, 26 ... heater (for stirring chamber), 27, 28, 29, 30 ... stirring blade, 35, 36, 37 , 38 ... crusher, 39, 40, 41, 42 ... exhaust port, 43 ... vacuum pump, 44, 45, 46, 47 ... intake port, 48, 49, 50, 51 ... ·valve.

Claims (9)

[Claims] 1. A continuous drying apparatus for gradually drying and continuously discharging an input object to be processed while transferring the inside of the apparatus, wherein a transfer path of the object to be processed is provided with a screw conveyor inside. A continuous drying apparatus comprising a cylindrical barrel and a stirring chamber provided with a stirring means therein, which are alternately connected in a plurality of stages. 2. The stirrer according to claim 1, wherein the stirring chamber is formed of a cylindrical member having a diameter larger than that of the barrel and having an axis parallel to an axial direction of the barrel. The continuous drying apparatus as described in the above. 3. The screw conveyor provided inside the barrel, wherein one end of the screw conveyor is located inside a stirring chamber connected to an upstream side of the barrel.
4. The continuous drying apparatus according to 1. 4. The apparatus according to claim 1, wherein at least one of the stirring chambers further includes a crushing means therein for crushing a lump of aggregated processing objects. The continuous drying device according to any one of the above. 5. The continuous drying apparatus according to claim 4, wherein the crushing unit is driven by the same drive shaft as a stirring unit provided inside the drying chamber. 6. The apparatus according to claim 1, wherein at least one of the drying chambers is connected to a vacuum exhaust unit.
A continuous drying apparatus according to any one of claims 1 to 5. 7. At least one of the drying chambers has an opening connected to a vacuum exhaust means and open to the atmosphere, and a valve whose opening can be adjusted is attached to the opening. The continuous drying apparatus according to any one of claims 1 to 5, wherein: 8. The screw conveyor has a large-capacity transfer operation mode for securing a transfer amount according to a drying capacity, and a small-capacity transfer operation mode for assisting stirring for drying in a stirring chamber. The continuous drying according to any one of claims 1 to 7, further comprising a function of automatically switching between the large-capacity transfer operation mode and the small-capacity transfer operation mode for operation. apparatus. 9. The continuous drying apparatus according to claim 1, further comprising a supply device for controlling a supply amount of the processing object to be supplied.