JPS6311590Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a hot air drying device that directly applies hot air to dry highly sticky muddy substances such as surplus activated sludge discharged from various wastewater treatment devices.

Conventionally, as a drying device for the above-mentioned slurry, a horizontal rotary stirring dryer has been used in many cases due to inhibiting factors such as the stickiness of the slurry.
However, in this type of apparatus, the volume occupied by the material in the cylindrical drying chamber is naturally small, and there is wasted space in the upper part, so the apparatus inevitably becomes larger. Therefore, in order to reduce the installation area and eliminate wasted space, vertical devices are effective. However, what is currently called a vertical type has a single-stage mixing and crushing mechanism at the bottom, which turns the dried material into fine powder and entrains it in the airflow, and is a type of flash dryer. Therefore, the existing density of the material is low, and the volume of the device is also large. In all of these devices, the material is fed by a screw feeder or the like, and the opening area of the discharge port is set to a size determined by the discharge amount, and no special consideration is given to its shape.

The drying device related to the present invention is vertical and has a high material density to reduce the device size.
This enables highly efficient and energy-saving drying processing.

Specifically, muddy materials are generally highly sticky when the water content is high, and when the water content is low, they tend to turn into powder when stirred. If the moisture content of the dried product is made too low, it will become similar to the flash dryer mentioned above. Therefore, by devising a stirring device and operation control method to maintain a certain intermediate moisture content, the material becomes a dried product with a rounded shape and a particle size that is small enough not to be scattered by air currents. , overflow is discharged from the upper outlet. The reason why this drying device is highly efficient is that the granular material is always present at a high density, and the newly supplied material forms a thin film on the surface of the existing particles while being swirled and flowing by the stirring device. This is because it is spread out and dried.

In other words, there is a material with a large dry surface area and a high moisture content on the surface, and this material is being updated one after another.

In order to carry out the process using such a drying mechanism, it is not enough to devise a stirring mechanism alone, and a mechanism for supplying the slurry must also be devised.

The desired function of this feeding mechanism is rapid and uniform dispersion of newly fed slurry within the dryer. Furthermore, in the case of materials containing many impurities such as sewage and human waste sludge, clogging of the supply port is a major problem.

The object of the present invention is to solve the above-mentioned problems and provide a vertical hot-air drying device that can efficiently granulate and dry slurry in an energy-saving manner.

This invention is equipped with a stirring mechanism consisting of a vertical rotating shaft and stirring blades attached to the rotating shaft in multiple stages above and below in a vertical cylindrical drying chamber, and an overflow outlet for dried material and a dry exhaust gas at the top of the drying chamber. In a drying device in which a hot air inlet is opened at the bottom of the drying chamber and a hot air inlet is opened at the bottom of the drying chamber, the upper surface of the stirring blade at the end in the rotation direction is inclined downward with respect to the horizontal plane, and the slurry which is connected to the slurry supply device is one or more material supply ports are formed at appropriate positions on the side wall of the drying chamber, and one or more material supply ports are formed on the bottom plate;
Alternatively, the hot air drying device for sludge is characterized in that a plurality of hot air drying devices are formed at appropriate positions on the side wall of the drying chamber and at a plurality of locations on either one of the bottom plate.

An example of the present invention will be described based on the drawings.
A vertical cylindrical drying chamber 1 is provided with a rotating shaft 4 provided in the vertical direction, and stirring blades 5 each consisting of two blades arranged on the rotating shaft 4 in three stages, upper, middle, and lower, and perpendicular to each other. A stirring mechanism 5' is provided. Drying room 1
Sludge supply pipes 10a and 10b are connected to the bottom plate 11 and side wall 1', respectively. tube 1
Branched from 0. Further, a hot air introduction pipe 7 is connected to the bottom of the drying chamber 1, and a downwardly inclined dry matter discharge pipe 3 is connected to the top of the side wall 1'.
An overflow discharge port 3' for dry matter is formed at the connecting portion of the dry matter discharge pipe 3.

The slurry supply pipe 10a branches into two symmetrically with respect to the center point of the bottom plate 11 (three or more branches may be used) and is connected in the vertical direction, and the slurry supply pipe 10b is connected to the center of the drying chamber 1. (in the normal direction of the side wall 1' of the drying chamber 1).
Alternatively, a plurality of them may be provided only on the side wall 1', one each on the bottom plate 11 and one on the side wall 1', or a plurality of each may be provided on the bottom plate 11 and the side wall 1'. In any case, a plurality of slurry supply pipes are provided.

Further, two hot air introduction pipes 7 (or three or more may be used) are connected to the side wall 1' in a tangential direction and a horizontal direction, and symmetrically with respect to the center point of the bottom plate 11.

The upper stirring blade 5 is disposed at a height position immediately adjacent to the overflow discharge port 3', and the lower stirring blade 5 is disposed at a position closest to the bottom plate 11. A scraping plate 6 is provided protruding in the vertical direction at a position immediately adjacent to the inner surface of the side wall 1' (wall surface of the drying chamber) and at the connection height of the slurry supply pipe 10b. In addition, it is more preferable to arrange a plurality of such middle stirring blades in the vertical direction so as to be orthogonal to each other.

The upper surface of each of the stirring blades 5 is inclined downward with respect to the horizontal plane at the end on the rotation direction side, and the angle of inclination is preferably 5 to 30 degrees. A two-piece type combined on opposite sides is optimal. Although the blade plate is shown as a flat plate in the illustrated example, it may be a curved plate.

The scraping plate 6 is for peeling off and removing muddy substances adhering to the inner surface of the side wall 1', and its outer surface faces toward the inner surface of the side wall 1' at its tip on the rotation direction side, and the inner surface faces toward the inner surface of the side wall 1'. It is preferable that the scraping plate 6 be inclined toward the inner surface of the side wall 1' along the rotating direction, and either a flat plate or a curved plate may be used.

In the figure, 2 is a dry exhaust gas discharge pipe, 9 is a valve, and a hot air supply source such as a hot air stove, a dry matter discharge device, a rotation drive mechanism for the rotating shaft 4, etc. are not shown.

In the present invention, as described above, slurry supply ports communicating with the drying chamber 1 are formed at multiple locations, and the upper surface at the end of the rotation direction of the stirring blade 5 is inclined downward with respect to the horizontal direction. This is very important.

Therefore, the sludge is transferred to the sludge supply pipes 10a and 1.
The hot air is supplied to the drying chamber 1 through the hot air introduction pipe 7.

While being dried, the slurry that has entered the drying chamber 1 is subjected to a kind of forced rolling granulation action by the action of the stirring blades 5, and becomes roundish granules. The sludge with a high moisture content that has just entered the drying chamber 1 adheres thinly and evenly to the surface of the dried material, which has already become granular, due to the action of the stirring blades 5. Therefore, the water evaporation rate is always kept at its highest. Particles that have become large in size due to dry matter adhering to and growing on the surface are divided into two or three at a certain point, and the particle size range of the dry matter depends on the properties of the slurry and the circumferential speed of the stirring blade 5. Equilibrium is reached at a value determined by

In this case, the slurry is supplied from multiple locations into the drying chamber 1 and quickly dispersed within the drying chamber, so compared to the case where the slurry is supplied from one location in a concentrated manner,
Sludge can be dried more uniformly and quickly.

The particles move circularly along the side wall 1' of the drying chamber by the stirring blade 5, and because the circumferential speed is fastest on the outer circumferential side, they perform a convection movement of rising on the side wall side and falling at the center. For this reason, the mixability within the drying chamber 1 is good, and unevenness in moisture content is extremely small.

Thus, the amount of dry granules commensurate with the amount of slurry supplied is continuously or intermittently discharged through the dry matter discharge pipe 3. In this way, by supplying the mud into the lower part of the drying chamber 1 and overflowing and discharging it from the upper part, it is possible to increase the packing density of the mud and dry matter in the drying chamber 1. Therefore, the drying device can be downsized.

As mentioned above, the hot air is introduced from the pipe line provided tangentially at the bottom of the side wall 1', thereby maximizing the contact time between the hot air and the sludge inside the drying chamber 1. By creating a swirling flow of hot air in the same direction as the stirring blade 5, it is possible to prevent the hot air inlet from being clogged with mud and to prevent short passes of the hot air.

In addition, in this embodiment, the slurry is supplied to the drying chamber 1.
Since this is carried out using multiple branch pipes from the bottom of the sludge supply pipe 1, it is possible to prevent undried material from being shot into the dry material discharge pipe 3.
The sludge coming out of 0a is cut into small pieces by the shearing force of the lower stirring blades, making it possible to quickly and uniformly disperse the sludge in the drying chamber 1.

In the device of the present invention, the slurry supply port is connected to the side wall 1' or the bottom plate 1, which is in contact with the swirling and flowing granular material layer.
1, and the slurry supply ports throughout the drying chamber are formed with multiple openings, so undried material will not be discharged through a short pass, and the newly branched and supplied material will be connected to the existing material. Since it quickly sinks into the granular material layer and is quickly dispersed and mixed, the granulation and drying process can be carried out extremely smoothly and efficiently. Therefore, it is possible to stably obtain a granular dried product with uniform particle size and moisture content and high mechanical strength.

In this way, it is important for the device of the present invention to quickly disperse the material into the drying chamber, but in the illustrated example, the material is branched and supplied from both the side wall 1' and the bottom plate 11, so it is difficult to disperse and mix the material. It can be done very effectively. In this case, the diameter of the slurry supply pipe varies depending on the amount of material supplied, but preferably has an inner diameter of 5 to 100 mm. In addition, the cross-sectional shape of the slurry supply pipe is such that the longitudinal direction extends from the bottom plate 1 between the position near the drying chamber 1 and the slurry supply port (discharge port).
The above-mentioned dispersion and mixing can be carried out extremely effectively by making the slits into an oblong or rectangular shape so as to coincide with the radial direction of the slurry 1 or the vertical direction of the side wall 1', and supplying the slurry in a thin form.

It is desirable that the inner wall surface of the drying chamber 1 is smooth, and therefore the slurry supply pipe is preferably connected so that no protrusions are formed on the inner wall surface. This is because if there are protrusions, material will adhere to these areas and gradually grow, interfering with smooth drying operations.

Furthermore, in the illustrated example, since the scraping plate 6 is disposed at the connection position of the slurry supply pipe 10b, there is no fear that the material will adhere to the drying chamber wall 1' and grow into a ring shape, and the material will not be supplied. Uniform dispersion of the added material will occur quickly.

It is preferable that the slurry supply device 8 be one that can forcefully feed the material in the form of a pump, as shown in the illustrated example, but this can supply the material stably even when the slurry supply pipe is branched into multiple pipes. It is from.

As described above, the present invention enables highly sticky mud to be dried quickly, uniformly, energy-savingly, and stably, and has high mechanical strength, making post-processing such as incineration extremely efficient. There are practical benefits such as a granular dried product that can be obtained by drying, a high packing density of slurry, and a simple and compact device structure.

[Brief explanation of the drawing]

The drawings are cross-sectional views showing embodiments of the present invention. 1... Drying chamber, 1'... Side wall, 2... Dry exhaust gas discharge pipe, 3... Dry material discharge pipe, 3'... Overflow outlet, 4... Rotating shaft, 5... Stirring blade, 5 ′...
Stirring mechanism, 6... scraping plate, 7... hot air introduction pipe,
8... Sludge supply device, 9... Valve, 10...
Main pipes, 10a, 10b... Sludge supply pipe, 11...
…Bottom plate.

Claims (1)

[Scope of Claim for Utility Model Registration] (1) A vertical cylindrical drying chamber is equipped with an agitation mechanism consisting of a vertical rotating shaft and stirring blades attached to the rotating shaft in multiple stages above and below. In a drying device in which an overflow discharge port and a dry exhaust gas discharge port are opened, and a hot air inlet port is opened in the lower part of the drying chamber, the upper surface of the rotation direction side end of the stirring blade is tilted downward with respect to the horizontal plane,
A slurry supply port connected to the slurry supply device is formed at one or more locations at an appropriate position on the side wall of the drying chamber, and at one or more locations on the bottom plate, or at an appropriate location on the side wall of the drying chamber. ,
A sludge hot air drying device characterized in that a plurality of locations are formed on either one of the bottom plates. (2) At least one of the sludge supply port connected to the side wall of the drying chamber and the sludge supply port connected to the bottom plate is a sludge supply pipe branched from a main pipe connected to a sludge supply source. The drying device according to claim 1 of the utility model registration claim, which is connected to the drying device. (3) The drying device according to claim 2, wherein the sludge supply pipe has a slit-like cross-sectional shape from a position near the drying chamber to the sludge supply port. (4) The drying device according to claim 2 or 3, wherein the slurry supply pipe is connected so that no protrusions are formed on the wall surface of the drying chamber.