JPS6121197Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to an improvement of a sludge dewatering device of the type that circulates an endless cloth belt.

The present applicant uses two endless cloth belts, a main and a subordinate, and arranges a mud supply box at the beginning of a gravity dewatering section that runs approximately horizontally or diagonally upward on the main belt that is stretched endlessly and circulates. Sludge is fed onto the main belt, gravity dewatering is performed in the above section, then a vertical belt is stacked on top of the main belt with the sludge sandwiched between them, and in that state the sludge is passed through a group of rolls with progressively smaller diameters. We have previously proposed several belt press type dewatering machines that further dehydrate sludge by sewing in a serpentine pattern and applying surface pressure.

This dehydrator is a complex and expensive device, so it is not suitable for small-scale sewage treatment plants and other treatment plants that generate a small amount of sludge, as the operating rate is low and equipment costs increase. For this reason, centrifugal separators for small-scale treatment plants and other press-type dehydrators have been developed, but they have problems such as noise generation and dewatering efficiency that is lower than belt press type dehydrators, so they are not satisfactory. isn't it. Further, as described above, the belt press type dehydrator has a complicated structure, so it is not suitable for miniaturization, and even if it is miniaturized, a significant cost reduction cannot be expected.

Therefore, the present invention uses an endless cloth belt like the belt press type dehydrator, but has a simple structure.
It was developed with the aim of creating a sludge dewatering device suitable for small-scale treatment plants that can be made compact, yet have excellent dewatering effects, and can be provided at a low cost.

Hereinafter, the present invention will be explained with reference to an illustrated embodiment.

Reference numeral 1 denotes an endless cloth belt, which has a gravity dewatering section that goes around a turning roll 2 that also serves as a tension adjustment roll, changes direction, and runs approximately horizontally or obliquely upward, and at the beginning of this section, a mud supply box 3 Sludge is supplied to the top of the belt at a substantially constant thickness, and as the belt travels through this section, it is dewatered by gravity on the back side of the belt. The amount of water removed in the gravity section accounts for most of the total amount of water removed by this dewatering device.

The belt 1 that has passed through the gravity dewatering section comes into contact with the outer periphery of the large-diameter main roll 4 with its sludge-laden outer surface and runs approximately half to three-quarters of the way around the lower surface of the main roll. The main roll 4 is driven by power to rotate in the direction of the arrow to circulate the cloth belt 1.
The rotation speed of the cloth belt 1 is approximately 0.2 to 0.8 m/
It is set to run at min.

On the lower surface of the main roll 4, which is in contact with the cloth belt 1, approximately in the rear half thereof, a pressure roll 5 having a smaller diameter than the plurality of main rolls is disposed so as to be circumscribed via the cloth belt, and The belt 1 is separated from the main roll 4 in a folded manner around the final pressure roll 5-N, and returns to the turning roll 2 while sequentially contacting the front pressure roll 5 on its inner surface, thereby increasing the tension. The adjustment roll 2 pushes the cloth belt 1 in the direction of the arrow with a spring, or a fluid pressure actuator operated by hydraulic pressure, pneumatic pressure, etc., and presses each pressure roll 5 against the main roll 4 based on the tension of the cloth belt applied. .

The main roll 4 and each pressure roll 5 are rolls made of metal such as iron or water-impermeable rolls having a synthetic rubber lining layer on the surface thereof. and,
The bearing of the main roll 4 is fixed to the frame and is immovable, whereas the bearing 5' of each pressure roll 5 is movable along the guide rail 6,
Moreover, the guide rail 6 can be adjusted by aligning the moving direction of the bearing 5' with the radial direction 4' from the axis of the main roll (Fig. 2) or intersecting this (Fig. 3). It is attached to the frame so that it can be used. For this purpose, for example bearing 5'
A pair of guide rails 6, 6 movably supporting each side of the bearing 5' are attached to a base plate 6a, and the base plate 6a is fixed to the frame with two or more bolts.
To adjust the direction of movement, loosen all bolts, rotate one of them as a fulcrum, and move the other bolts in an arcuate hole centered on the bolt.

The reason why the pressure roll 5... and its support means are made in this way is that the force pressed against the main roll 4 is gradually or stepwise from the first pressure roll 5-I to the last pressure roll 5-N. This is to increase the dehydration rate and to increase the value so that the desired dehydration rate can be finally obtained. For example, when the moving direction of the bearing of the first pressure roll 5-I is directed toward the axis of the main roll 4 (Fig. 2), the tension of the cloth belt is aKg/cm, and the wrapping angle of the belt around the roll is α°. At this time, if the roll's own weight is ignored, the force with which the pressure roll 5-I is pressed against the main roll 4 is 2 cm per cloth width/cm.
a・sinα/2Kg). Therefore, if the diameters of the front and rear pressure rolls are different, the value will change depending on the wrap angle, and if the bearing movement direction is crossed with the radiation from the main roll axis, the value will change. Its value changes further.

In short, by making the pressure rolls have different diameters at the front and back, in this way the force with which the pressure rolls are pressed against the main roll 4 is increased in order or in stages from the first one to the last one. The sludge dewatered in the gravity dewatering section passes through the section where the belt 1 contacts the lower surface of the main roll 4. Pressure rolls 5 are strongly pressed against the main roll 4 gradually or in stages... They are pressurized in groups and further dehydrated to form a cake with a desired dehydration rate. Immediately after leaving this section, scrapers 7 It is peeled off from the outer surface of the belt and the surface of the main roll. Of course, while the cloth belt 1 is returning to the turning roll 2, a nozzle 8 for spraying cleaning water onto the cloth belt is disposed to clean the cloth belt.

In addition, in this embodiment, the tension was adjusted by the turning roll 2, but the tension adjustment roll is the turning roll 2.
It may be provided separately. Further, 9 is a correction roll for correcting meandering of the cloth belt, but this correction may be performed by a turning roll. 10 is cloth belt 1
is a guide roll for making the section surrounding the lower surface of the main roll 4 as long as possible, but this is not necessarily necessary.

The sludge supplied to the sludge supply box 3 is mixed with a cationic polymer flocculant by rapid stirring, reacted with each solid particle of the sludge, and then the anionic polymer flocculant is mixed with slow stirring. It is preferable that the solid particles be prepared in advance so as to grow into large flocs containing almost no water, so that gravity dehydration is good and the fabric belt is not clogged. This preparation can be carried out by passing the sludge through separate flocculation reactors equipped with a rapid stirrer and a slow stirrer, but this method has been proposed by the applicant in Japanese Patent Application No. 56-16819 (Japanese Unexamined Patent Application No. 57-132541). One flocculation reaction tank 1 proposed in
1 can be suitably carried out.

For details of this reaction tank 11, please refer to the above-mentioned patent application.

This idea is based on the conventional belt press type dehydrator, in which endless main and sub-fabric belts are circulated, and in pressurized dehydration, sludge is sandwiched between both belts and sewn in a staggered manner between a large number of pressure roll groups. Instead of using a more complicated structure, only one cloth belt is used, and the tension of the cloth belt is used to press the pressure roll against the main roll, allowing the sludge to pass through and dewater under pressure. I did it like this. Therefore, its structure is extremely simple, and it has the excellent feature of being compact and yet able to obtain a cake with a dehydration rate comparable to that of a large belt press type dehydrator. This provides a sludge dewatering device that is ideal for large-scale treatment plants.

In particular, in the latter half of the pressing and dewatering process in which the pressure roll 5... circumscribes the main roll via the cloth belt, pressure is applied to the pressure roll from the returning cloth belt, and that pressure is applied to the subsequent pressurization. (a) As the cloth belt runs, dehydration progresses, the water content decreases, and the cake strength increases, so that ideal pressurized dehydration can be achieved in which the pressing force gradually increases. .

(b) Since the pressing force of the pressure roll is proportional to the tension of the cloth belt, this pressing force can be easily adjusted to an optimal value by changing the tension of the cloth belt according to the dewatering situation.

(c) Even if the thickness of the cake changes, the applied pressure hardly changes, allowing smooth dehydration.

(d) The force applied from the cloth belt to the pressure roll is uniform across the width of the roll, so no undue force is applied to the roll or shaft. Therefore, the structure of the pressure roll can be simplified, and problems with strength and durability are less likely to occur.

(e) The pressure roll receives rotational force from the fabric as it moves back and forth, so it rotates smoothly and does not damage the roll or fabric.

This provides revolutionary effects not found in conventional dehydrators.

[Brief explanation of the drawing]

FIG. 1 is a schematic longitudinal cross-sectional view showing an embodiment of this invention, and FIGS. 2 and 3 are front views showing the state of the guide rail, which is the support means for the bearing of the pressure roll, and its substrate. Inside, 1 is cloth belt, 4 is main roll, 5
is a pressure roll, is a gravity dehydration section, and is a pressure dehydration section.

Claims (1)

[Scope of Claim for Utility Model Registration] (1) In a sludge dewatering device that dewaters sludge by supplying sludge to the beginning of a gravity dewatering section that moves substantially horizontally or diagonally upward on a circulating endless cloth belt, At the other end is a large diameter main roll,
A plurality of pressure rolls facing the lower surface and movable toward and away from the main roll are arranged,
A cloth belt is passed between the underside of the main roll and the pressure roll group to sandwich the sludge between the main roll and the cloth belt, and the sludge is passed around the final pressure roll and contacted from below each pressure roll for gravity dewatering. A sludge dewatering device characterized in that pressure dewatering is performed by returning to a section and pressing each pressure roll against a main roll using the tension of a cloth belt tensioned by a tension adjustment roll. (2) In the sludge dewatering apparatus according to claim 1 of the utility model registration, the bearing means that supports the bearing of each pressurizing roll so that it can move toward and away from the main roll is arranged such that the direction of movement of the bearing is from the axis of the main roll. Sludge dewatering equipment that is adjustable against radiation.