JP2001033167A - Dryer and drying method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance efficiency of drying operation by providing a dryer body, and a filter for applying fine powder of a matter to be dried positioned on the boundary to an exhaust pipe extending from the dryer body thereby preventing fine powder on the matter being dried from adhering to the exhaust pipe. SOLUTION: A matter being dried, i.e., sludge, is fed from a throw-in opening 2 into a dryer body 1 where it is heated and stirred. As the drying time elapses, moisture is evaporated and the sludge is dewatered. The moisture is discharged through a discharge pipe 21 standing on the upper wall of the dryer body 1 to the outside thereof. A filter holder 20 is provided at the joint of the discharge pipe 21 to the upper wall of the dryer body 1 and a filter 22 is fixed in the holder 20. The filter 22 is a belt type filter fed out sequentially from a feed roll tuned to the rotation of a timing belt entrained about a timing pulley. According to the arrangement, good filter performance is sustained and fine powder discharged from the discharge pipe 20, along with steam, can be captured and removed surely.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a dryer for drying sewage sludge and the like, and a method for drying the same.

[0002]

2. Description of the Related Art In recent years, techniques for effectively utilizing sludge such as sewage have been developed. For example, such techniques are used as compost or as solid fuel.

[0003] The water content of sludge after dewatering is generally on the order of 60 to 80% by weight of moisture (hereinafter referred to as WB). However, when used as compost, it is desired that the content be 30% by weight or less WB so as to be suitable for storage and spraying. Also, add waste plastic to sludge,
When used as a solid fuel, it is desirable to reduce the water content as much as possible, and it is desired that the water content be 10% by weight or less.

[0004] When drying sewage sludge, a dryer is usually used.

[0005] Referring to FIG. 5, a conventional drier is provided with an input port 2 for inputting a dried substance such as sewage sludge at an upper portion of a main body 1 of the drier. A discharge port 3 for discharging a dried product is provided at a lower portion of the dryer main body 1. The inlet 2 and the outlet 3 are closed by lids 4 and 5 while drying the dried product.

[0006] The side wall portion of the dryer main body 1 is composed of walls 6 and 7 having a double structure of an outer side and an inner side, and a gap 8 is provided between the two walls 6 and 7. An inflow port 9 for introducing a heat medium is provided at a lower end of the gap 8, and an outflow port 10 for outflow of the heat medium is provided at an upper end.

[0007] A rotating shaft 11 is provided at the center of the dryer main body 1. The upper end of the rotating shaft 11 is supported by the upper wall of the dryer main body 1, and the lower end is connected to a motor 12. A stirring blade 13 spirally surrounding the rotating shaft 11 is fixed to the rotating shaft 11 by a number of support arms 14. In addition, on the upper part of the dryer main body 1, the dryer main body 1 is provided.
A thinner exhaust pipe 15 is attached.

With the above-described structure, when drying the object to be dried, the motor 12 is driven to rotate the rotating shaft 1.
When 1 rotates, the stirring blade 13 also rotates. Inlet 9
The heat medium is introduced as shown by the arrow a from the outlet, and is drawn out from the outlet 10 as shown by the arrow b. During this time, the inside of the dryer main body is heated by the heat of the heat medium, and the object 16 to be dried input from the inlet 2 is stirred by the rotation of the stirring blades 13 and dried by the heat in the dryer main body 1. The dried object 16 is discharged from the discharge port 3.

Here, the heating of the main body 1 of the dryer with the above-described heat medium can be performed even after the material 16 to be dried is charged. When the dried object 16 is dried, the water vapor contained in the dried object 16 goes out of the dryer 1 through the exhaust pipe 15, and the fine powder generated by the drying of the dried object 16 together with the water vapor It is discharged from the exhaust pipe 15.

[0010]

Since the conventional dryer has a structure in which steam and fine powder are discharged from the exhaust pipe 15 to the outside, the outer surface of the exhaust pipe 15 comes into contact with the outside air and the exhaust pipe 15 The temperature of the inner wall becomes lower than the internal temperature of the dryer main body 1, and the fine powder comes into contact with and adheres to the exhaust pipe 15. In addition, a part of the water vapor is condensed, and the fine powder discharged together with the water vapor adheres to the inner wall of the exhaust pipe 15. The attached fine powder gradually increased in thickness and blocked the exhaust pipe 15 to lower the drying efficiency.

SUMMARY OF THE INVENTION An object of the present invention is to provide a dryer and a method for drying the same, which eliminate the above-mentioned disadvantages and prevent the fine powder of the material to be dried from adhering to the exhaust pipe, thereby improving the drying efficiency.

[0012]

In order to achieve the above-mentioned object, the present invention relates to a dryer having a dryer body for drying an object to be dried, and an exhaust pipe extending from the dryer body, the exhaust pipe being narrower than the dryer body. The dryer is provided with a filter for adhering the fine powder of the object to be dried on the boundary between the dryer body and the exhaust pipe.

This prevents the fine powder of the material to be dried from adhering to the exhaust pipe, thereby improving the drying efficiency, shortening the drying time or improving the degree of drying.

The filter can be replaced by a filter changer or a belt-shaped filter, and replacement and cleaning of the filter are easy.

[0015] Further, since the filter cleaning means is provided in the exhaust pipe so as to return the fine powder adhering to the filter to the direction of the dryer body, the frequency of replacing the filter can be reduced, and in addition, the fine powder moves out of the pipe. Not only is the amount of scattered air reduced, air pollution is prevented, but the collection of fine powder is also efficient.

Further, as a filter cleaning means, a nozzle for ejecting a fluid whose tip is directed to the filter into the exhaust pipe is used, and the fluid ejected from the nozzle is air, water or water vapor which has no problem even if it is discharged to the atmosphere. Non-combustible gases such as nitrogen and carbon dioxide are used for the object to be oxidized.

Further, in the drying method of the dryer according to the present invention, the step of returning the fine powder adhering to the filter to the direction of the main body of the dryer is completed, and every time the object to be dried is put into the main body of the dryer.
Since the method is performed, the amount of fine powder discharged to the outside is small, and the fine powder can be reliably recovered.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIG. In the description, since the present invention is an improvement of the conventional device, members which are the same as those of the conventional device are denoted by the same reference numerals, description thereof will be omitted, and only newly added members will be described with the new numbers.

A filter holder 2 is provided on the upper wall of the dryer body 1.
An exhaust pipe 21 provided with a zero is attached, and a filter 22 is placed in the filter holder 20. Same filter 2
Numeral 2 removes the fine powder discharged from the exhaust pipe 20 together with the water vapor generated during the drying of the material 16 to be dried. When the fine powder adheres to the filter 22 and the filter function is deteriorated, the filter 22 is removed from the filter holder 20.
It can be removed and replaced with a new one, or cleaned.

As shown in FIGS. 2A and 2B, the above-mentioned filter drives a timing belt 27 wrapped around the timing pulleys 24, 25 and 26 at a predetermined speed by a motor 28, and forms a belt-shaped filter. The take-up roll 3 rotates in synchronization with the timing pulley 25 from the unwind roll 29 that rotates in synchronization with the timing pulley 26
By continuously moving the filter to zero, the filter can always be used in a new state.

As shown in FIGS. 3A and 3B, the filter holder 32 containing the used filter 30 and the unused replacement filter 31 is moved by the cylinder 33 to the used filter 30 and the replacement filter 31. By using the filter changer for switching the filter, the replacement work and cleaning of the filter can be simplified.

It is also possible to use a filter cleaning means for removing fine powder adhering to the filter without replacing the filter.

Next, one embodiment will be described with reference to FIG. 4. An exhaust pipe 41 is attached to the upper wall of the dryer body 1 via a filter 40. The exhaust pipe 41 has a front end with a lid 4.
2 and an exhaust port 43 bent in a right angle direction is provided. Air or water is introduced into the exhaust pipe 41 from the fluid supply source (not shown) via the on-off valve 44 via the pipe 45 as shown by the arrow c to the lid 42 at the tip end, and is ejected toward the filter 40 at high pressure. Nozzle 46 is mounted.

The drying method will now be described. The sludge to be dried is manually or automatically supplied from the inlet 2 into the main body 1 of the dryer. The sludge which was about 80% by weight WB at the time of supply while being heated and stirred is dewatered with the elapse of the drying time, and the water evaporates and is discharged out of the dryer through the exhaust pipe 41 provided at the upper part of the dryer main body 1. % By weight or less.

On the other hand, as the dewatered sludge is dried, the granularity is further reduced from granular to fine, and a part thereof becomes fine powder. This fine powder is discharged together with the evaporating moisture into the exhaust pipe 41.
During discharge to the exhaust port 43, the fine powder is attached and captured by the filter 40, and only water is discharged.

After a predetermined drying time has passed, the sludge dehydrated to a predetermined water content is taken out from the outlet, one batch of drying process is completed, the next sludge is charged, and the above-described drying process is repeated. Done.

During this time, the replacement of the filter or the removal of the fine powder adhering to the filter can be performed each time one batch of the drying process is completed or each time a new material to be dried is introduced. Here, when removing the fine powder adhering to the filter immediately after putting in the dry matter, the fine powder is returned on the dry matter together with the sprayed water, etc., and the moisture of the dry matter strictly increases. However, the water for washing is much less than the water in the sludge and does not significantly affect the drying process.

[0028]

According to the present invention, a filter is provided at the boundary between the main body of the dryer and the exhaust pipe, so that the fine powder is removed by the filter, and a dryer having improved drying efficiency and a method thereof can be realized.

[Brief description of the drawings]

FIG. 1 is a schematic view of a dryer showing one embodiment of the present invention.

FIGS. 2A and 2B are explanatory views of the belt-shaped filter replacement device of the present invention, wherein FIG. 2A is a plan view, and FIG. 2B is an enlarged view of FIG.

FIG. 3 is an explanatory view of a filter changer of the present invention;
(A) is a plan view, and (B) is an enlarged view of the AA cross section of (A).

FIG. 4 is an explanatory view of a filter cleaning means of the present invention.

FIG. 5 is an explanatory view of a conventional dryer.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Dryer main body 2 Input port 3 Discharge port 4, 5 Lid 6 Outer wall 7 Inner wall 8 Gap 9 Inflow port 10 Outflow port 11 Rotary shaft 12 Motor 13 Stirring blade 14 Support arm 15, 21 Exhaust pipe 20 Filter holder 22, 23 Filter 24 , 25, 26 timing pulley 27 timing belt 28 motor 29 unwind roll 30 take-up roll 40 filter 41 exhaust pipe 42 lid 43 exhaust port 44 on-off valve 45 pipe 46 nozzle

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) F26B 11/20 F26B 11/20 F term (reference) 3L113 AA09 AB05 AC47 AC68 AC83 BA37 DA01 DA10 DA22 DA26 4D058 JA12 JA23 KC83 MA11 MA12 SA20 4D059 AA03 BD11 BD24 BJ02 CA14 CB17

Claims (7)

[Claims] 1. A dryer comprising: a dryer body for drying an object to be dried; and an exhaust pipe extending from the dryer body, the exhaust pipe being narrower than the dryer body. A dryer equipped with a filter for adhering fine powder. 2. The dryer according to claim 1, wherein the filter is replaceable by a filter changer. 3. The dryer according to claim 1, wherein the filter is a belt-shaped filter that moves at a predetermined speed. 4. The dryer according to claim 1, further comprising a filter cleaning unit configured to return fine powder attached to the filter to the exhaust pipe toward the dryer body. 5. The dryer according to claim 4, wherein said filter cleaning means is a nozzle for ejecting a fluid whose tip is directed to the filter. 6. The dryer according to claim 5, wherein the fluid is any one of water, steam, air, and a nonflammable gas. 7. A drying method for a dryer, comprising a step of returning fine powder adhering to a filter to a direction of a main body of the dryer, wherein the drying is completed, and each time a next object to be dried is put into the main body of the dryer. And a drying method for a dryer.