JPS6321994Y2 - - Google Patents

Description

[Detailed description of the invention] This invention uses sludge produced during the clarification of water, wastewater, and other liquids, or flocculated sludge obtained by adding organic polymer flocculants or other flocculants to these sludges. This invention relates to an improvement of a screw press type dehydrator having a cylindrical outer cylinder, which can produce a dehydrated cake with a significantly low water content by continuously compressing and dewatering with blades and producing a dehydrated cake with extremely low water content.

As shown in Fig. 1, the conventional screw press has an outer cylinder 3' of a cylindrical shape provided between the sludge supply port 1' of the sludge hopper 2' and the dewatered cake discharge port 6', and a screw on the outer periphery. The sludge is composed of a screw shaft 5' having blades 4', and the volume of the annular gap between the outer cylinder 3', the screw shaft 5', and the screw blades 4' is sequentially reduced as appropriate, and the sludge is fed into the sludge supply port 1'. in the axial direction by the rotation of the screw shaft 5'.
That is, it has a structure and function in which the dehydrated cake is extruded in the direction of the dehydrated cake discharge port 6' and squeezed sequentially, the liquid squeezed out from the sludge is discharged from the outer cylinder 3', and the dehydrated cake is taken out from the dehydrated cake discharge port 6'. ing.
Note that 7' is a drive shaft for the screw shaft 5', and 8' is a drive device for the screw shaft 5'.

By the way, in general, in the case of sludge overflow, the amount of liquid V that flows during time θ increases as the resistance R _c of the cake formed on the material surface or the resistance R _M of the material decreases, that is, the overspeed increases. becomes large, and the following relational expression holds true.

dV/A・dθ=ΔP/μ・(R _M +R _C ) A: Material area ΔP: Overpressure (pressure drop in packed bed) μ: Liquid viscosity Therefore, if you want to increase overspeed, cake It is necessary to keep the resistance R _C of the material and the resistance R _M of the material small. Normally, for sludge dewatering, an organic polymer coagulant or inorganic coagulant is added as a super-aid to reduce the resistance R _C of the cake formed on the material surface. It has been modified to reduce the resistance of the material.
In order to reduce R _M , the air permeability is increased and thinner materials are used.

In the case of a conventional screw press, as shown in Fig. 1, the cake formed on the inner surface of the outer cylinder 3' is scraped off with the screw blade 4' to prevent the cake from clogging the outer cylinder 3' surface. The resistance of R _C
In actual operation, the number of revolutions of the screw shaft 5' is increased, the number of times the screw blade 4' scrapes the inner surface of the outer cylinder 3' is increased, or the inner surface of the outer cylinder 3' and the screw blade 4 are increased. The screw blade 4' is assembled so that the clearance with the tip is as small as possible, and the cake formed on the inner surface of the outer cylinder 3' is completely scraped off. Also,
The material resistance R _M is made small by using the outer cylinder 3' with a large porosity.

As described above, in the conventional screw press, the above-mentioned methods and operations are taken to reduce the cake resistance R _C and the material resistance R _M , but the following drawbacks occur.

First, by increasing the number of revolutions of the screw shaft 5' and increasing the number of times the screw blade 4' scrapes the inner surface of the outer cylinder 3', the cake formed on the inner surface of the outer cylinder 3' can be scraped off from the inner surface of the outer cylinder 3' in a short time. However, as the rotational speed of the screw shaft 5' increases, the sludge introduced into the sludge supply port 1' is discharged from the dewatered cake discharge port 6' in a short period of time, resulting in insufficient dewatering and a cake with a high moisture content. It becomes expelled.

In addition, it is necessary to assemble so that the clearance between the inner surface of the outer cylinder 3' and the tip of the screw blade 4' is small, and to completely scrape off the cake formed on the inner surface of the outer cylinder 3' with the screw blade 4'. This is easy to some extent, but in actual equipment larger than the test equipment, advanced technology or precision is required, and if the technology or precision is insufficient, the screw blade 4' will come into contact with the outer cylinder 3', causing accidents such as wear or damage of the outer cylinder 3'. occurs.

Furthermore, if the resistance R _M of the material is reduced by using an outer cylinder 3' with a large porosity, there is a risk that the cake will flow out of the outer cylinder 3' due to the increased porosity, resulting in a decrease in the recovery rate.

The object of the present invention is to economically provide a sludge dewatering machine that can effectively eliminate the above-mentioned drawbacks of conventional screw press type dewatering machines.

That is, in the present invention, a screw shaft having screw blades on the outer periphery is rotatably arranged in an outer cylinder of a cylindrical member having a sludge supply port and a cake discharge port, and the screw shaft is formed by the outer cylinder, the screw shaft, and the screw blades. The tip of a screw blade near the sludge supply port in a screw press type dehydrator in which the gap is gradually reduced toward the cake discharge port, and the sludge is compressed and dehydrated by rotation of the screw shaft and discharged from the cake discharge port. This screw press type dewatering machine is characterized in that a plurality of cake scraping rods are fixedly arranged between the screw blade side surfaces in a narrow gap parallel to the inner surface of the outer cylinder and in close proximity to the inner surface.

Hereinafter, embodiments of the present invention will be described with reference to FIGS. 2 to 4.

The dewatering machine shown in FIGS. 2 and 3 has a conical shape in which screw blades 4 are protruded from the outer periphery of a cylindrical outer cylinder 3 provided with a sludge supply port 1 and a cake discharge port 6 of a sludge hopper 2. The screw shaft 5 is arranged so as to be rotatable by a drive shaft 7 and a drive device 8, and the screw blade 4 near the sludge supply port 1
It has a structure in which a plurality of cake scraping rods 9 are fixed between the sides of the screw blades parallel to the inner surface of the outer cylinder 3 and in close proximity to the inner surface with a small gap between the ends of the screw blades.

Therefore, the sludge hopper 2 with the sludge supply port 1
The sludge introduced into the tube flows into the annular gap formed by the outer tube 3, the screw blade 4, and the screw shaft 5, and the liquid is discharged from the outer tube 3, and gradually adheres to the inner surface of the outer tube 3 as a cake.
The dehydrated cake is then conveyed to the cake discharge port 6 side by the rotation of the screw shaft 5 while being scraped off by a scraping rod 9 or the like, and is sequentially filtered and squeezed by reducing the volume of the annular gap. It has a function of being taken out from the discharge port 6.

That is, in the screw press of the present invention, the scraping rod 9 is placed within one pitch of the screw blade 4.
By installing this, it is possible to scrape off the cake formed on the inner surface of the outer cylinder 3 n times faster than with a conventional screw press even at the same screw shaft rotation speed.
This reduces the resistance R _C of the cake and increases the overspeed, resulting in effects such as an increase in the throughput of solids and the ability to stably obtain a dehydrated cake with a low water content.

In addition, in the conventional screw press, the cross section of the outer cylinder 3' in the direction of the screw shaft 5' (the axial cross section of the outer cylinder 3')
In this case, the part where the screw blade 4' and the outer cylinder 3' are closest is only the tip of the screw blade 4',
Because they are close to each other in a dotted manner, it is difficult to assemble with a uniform clearance between the inner surface of the outer cylinder 3' and the screw blade 4' when removing the outer cylinder 3' and attaching a material with a different porosity and reassembling it. It was.

In contrast, in the screw press of the present invention, a scraping rod 9 is attached between the screw blades 4, 4 parallel to the inner surface of the outer cylinder 3, and since they are linearly adjacent to each other, reassembly is easy. Moreover, this allows assembly with a smaller clearance between the inner surface of the outer cylinder and the tip of the screw blade than in conventional screw presses, and the cake can be scraped off almost completely in this area compared to conventional screw presses. The resistance R _C becomes smaller, resulting in effects such as an increase in the throughput of solids and the ability to stably obtain a dehydrated cake with a low moisture content.

In the device of the present invention, the mounting position of the scraping rod 9 in the direction of the screw shaft 5 is limited to the vicinity of the sludge supply port 1. This has an effect on the part where fluidized sludge is charged into the sludge hopper 2 and is discharged from the outer cylinder 3 until it becomes cake-like.
A scraping rod 9 is also attached to the part after the fluidized sludge that has been pushed out from the vicinity of the sludge supply port 1 toward the cake discharge port 6 side by the rotation of the screw shaft 5 and has become cake-like. The cake that has lost its fluidity is given a force in the circumferential direction of the screw shaft 5 by the rotation of the screw shaft 5, and the screw blade 4
This is because the cake rotates together (the cake adheres to the screw blade 4 and the screw shaft 5 and rotates together at that point), and the cake cannot be fed in the direction of the cake discharge port 6.

The fluidity of sludge varies depending on the type or composition of the sludge and cannot be expressed numerically, so the mounting position of the scraping rod 9 in the direction of the screw shaft 5 is from the starting end of the screw shaft 5 on the sludge supply port 1 side. Although it is not possible to express the exact position with numerical values, it is usually preferable to install the screw blade between the screw blades 4, which is approximately twice the length of the sludge supply port 1 in the direction of the screw shaft 5.

The mounting position of the scraping rod 9 in the radial direction of the screw shaft 5 is assumed to be at the tip of the screw blade 4, but will be illustrated and explained more specifically.

The mounting position is shown in Figure 4, but the scraping rod 9
is parallel to the inner surface of the outer cylinder 3 and the screw blades 4, 4
It is preferable to bridge the side surfaces 4-B and 4-B of the scraping rod 9, and to attach the scraping rod 9 so that the inner surface of the outer cylinder 3 coincides with the outer circumferential surface 4-A of the screw blade 4.

If the surface of the scraping rod 9 on the inner surface of the outer cylinder 3 protrudes too much from the screw blade outer peripheral surface 4-A toward the outer cylinder 3,
The clearance between the inner surface of the outer cylinder 3 becomes smaller and the outer cylinder 3
Although the cake adhering to the inner surface can be well scraped off, there is a risk that the cake will come into contact with the inner surface of the outer cylinder 3 and cause accidents such as abrasion or breakage of the outer cylinder 3.

The surface of the scraping rod 9 on the inner surface of the outer cylinder 3 is the outer peripheral surface 4-A
If it is retracted too much, the clearance between this surface and the inner surface of the outer cylinder 3 becomes too large, the effect of scraping off the cake formed on the inner surface of the outer cylinder 3 decreases, and the resistance R _C of the cake on this surface becomes too large. speed becomes smaller.

The cross-sectional shape of the scraping rod 9 is not particularly limited.

It is desirable that the thickness of the scraping rod 9 be made as thin as possible within the range permitted by mechanical strength. If the scraping rod 9 becomes too thick, the rotation of the screw shaft 5 will apply a force in the circumferential direction of the screw shaft 5 to the sludge, and it will rotate together with the screw blades 4, preventing the sludge from being pushed out in the direction of the cake discharge port 6. Sometimes I get used to it. Although the thickness of the scraping rod 9 usually varies depending on the size of the device, it is preferable that the diagonal length of the cross section in the radial direction is usually about 5 to 15 mm.

In this way, the device of the present invention has a cake scraping rod fixedly disposed between the tips of the screw blades near the sludge supply port, parallel to the inner surface of the outer cylinder, and in close proximity to the inner surface of the outer cylinder. The cake formed on the inner surface of the outer cylinder can be scraped off together with the screw blade in a short time, and when assembling the device, it is easy to assemble the device with a small clearance between the inner surface of the outer cylinder and the tip of the screw blade. The cake that has formed on the inner surface of the cylinder can be almost completely scraped off, and when the liquid is discharged from the outer cylinder in this area, the resistance caused by the cake itself is reduced, so a large amount of liquid can be discharged within a certain amount of time. Compared to conventional screw press type dehydrators, it is possible to significantly reduce the moisture content of the dehydrated cake and increase the throughput of solids, and the equipment structure is simple and inexpensive to manufacture and maintain. It is also extremely simple and offers many benefits.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a conventional example, FIG. 2 is a plan view of an embodiment of the present invention, FIG. 3 is a sectional view thereof, and FIG. 4 is an enlarged sectional view showing the mounting position of a scraping bar. 1...Sludge supply port, 2...Sludge hopper, 3...
...Outer cylinder, 4...Screw blade, 4-A...Blade outer peripheral surface, 4-B...Side surface, 5...Screw shaft,
6... Cake discharge port, 7... Drive shaft, 8... Drive device, 9... Scraping bar.

Claims (1)

[Scope of utility model registration request] A screw shaft having screw blades on the outer periphery is rotatably arranged in an outer cylinder of a cylindrical filter medium having a sludge supply port and a cake discharge port, and the outer cylinder,
In a screw press type dewatering machine, the gap formed by the screw shaft and the screw blade is gradually reduced toward the cake discharge port side, and the sludge is compressed and dehydrated by the rotation of the screw shaft and discharged from the cake discharge port, A plurality of cake scraping rods are fixedly disposed between the tips of the screw blades in the vicinity of the sludge supply port in parallel with the inner surface of the outer cylinder and directly in the vicinity of the inner surface with small gaps between the sides of the screw blades. Screw press type dehydrator.