JPH028637Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field] The present invention uses sludge generated during the clarification of water, wastewater, and other liquids, or flocculated sludge obtained by adding a flocculant to this sludge and flocculating it. , relating to an improvement of a screw press type dehydrator equipped with a cylindrical outer cylinder that can produce a dehydrated cake with a significantly low water content by continuously compressing and dewatering the liquid using a screw shaft with screw blades. It is.

[Conventional technology]

A conventional screw press type dewatering machine, for example, as shown in FIG. The sludge put into the port 1' is pushed out in the axial direction, that is, in the direction of the dewatered cake discharge port 6' by the rotation of the screw shaft 5', and is sequentially squeezed, and the liquid squeezed from the sludge is discharged from the outer cylinder 3'. , is configured to take out the dehydrated cake from the dehydrated cake outlet 6',
This dehydrated cake discharge port 6' is narrowed with a tapered cone 8' to increase discharge resistance and adjust the water content of the dehydrated cake. In the figure, 2' is a hopper, 7' is a bearing, and 9' is a drive device.

When dewatering sludge using such a screw press, the dewatering performance varies greatly depending on the properties of the sludge. It is often operated by changing operating conditions such as sludge pushing pressure.

[The problem that the idea attempts to solve]

Therefore, in such a dehydrator, a pressure detection port 10' is provided in the outer cylinder 3' at the end of the screw blade 4' on the side of the dehydrated cake discharge port 6', and the screw shaft 5'
When the pressure is measured by rotating the sludge, the pressure of the sludge during dewatering shows a pressure distribution as shown in Figure 3. That is, when the screw blade 4' (the top of the mountain) is located at the pressure detection port 10', the second
As shown by the solid line in the figure, when the surface of the screw blade 4' on the dehydrated cake discharge port 6' side approaches the pressure detection port 10', the maximum pressure Pa is indicated, and the rotation of the screw shaft 5' causes the screw blade 4' moves to the right in the drawing, and the lowest pressure Pb is indicated when the surface of the screw blade 4' on the hopper 2' side approaches the pressure detection port 10' as shown by the two-dot chain line.

In this way, the pressure of the sludge gradually increases as the screw shaft 5' rotates, while it shows a change that decreases extremely rapidly from the highest pressure Pa to the lowest pressure Pb before and after the screw blade 4'. In other words, considering the cross section perpendicular to the axis of the dehydrator on the side of the dehydrated cake discharge port 6' at any moment during the operation of the dehydrator,
The distribution of the sludge pressure applied to the screw shaft 5' and the outer cylinder 3' is as shown in Fig. 3, and when considering one point on the inner surface of the outer cylinder 3', the sludge pressure changes from moment to moment.
This means that it changes periodically and shows a sudden change when passing through the screw blade 4' (pressure distribution curve C').

As mentioned above, in the conventional screw press type dehydrator, uneven loads are generated on the screw shaft 5' and the outer cylinder 3' in the cross-sectional direction perpendicular to the axis, resulting in unnecessary deformation of the dehydrator body. There were some problems, such as problems such as oxidation and shortening of equipment life.

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

[Means to solve the problem]

In the present invention, a screw shaft having screw blades on the outer periphery is rotatably arranged in an outer cylinder of a cylindrical material having a sludge supply port and a cake discharge port, and the cake is discharged while compressing and dewatering the sludge by rotation of the screw shaft. In a screw press type dehydrator that discharges the cake from the outlet, the gap between the outer surface of the screw shaft and the inner surface of the outer cylinder is configured to become smaller in the direction of the cake discharge port, and from one end on the supply port side to the other end on the discharge port side. A plurality of screw blades are installed in the screw shaft portion up to the screw press, and the height of each screw blade from the outer surface of the screw shaft is equal in any cross section perpendicular to the axis of the screw press, and the circumference of the screw shaft is This is a screw press type dehydrator in which the cake is equally divided by blades and a tapered cone is provided near the cake discharge port.

〔Example〕

An example of the present invention will be described with reference to the drawings.
In Fig. 4, a sludge supply port 1 via a hopper 2 is provided at one end, and a dewatered cake discharge port 6 is provided at the other end in an external cylinder 3 made of an open horizontal cylindrical member, concentrically with the external cylinder 3. , 2 screw blades on the outer periphery
The rows 4a and 4b are planted, and the dehydrated cake outlet 6
A screw shaft 5 whose diameter gradually increases toward the center is rotatably provided. Further, a tapered cone 8 having the same structure as the conventional one is provided near the dehydrated cake outlet 6.

The two screw blades 4a and 4b have the same height from the outer surface of the screw shaft 5 in a cross section perpendicular to the axis of the screw press at any position from the sludge supply port 1 side to the dehydrated cake discharge port 6 side, and The screw shaft is arranged so as to equally divide the circumference of the screw shaft into two.

In addition, in FIG. 4, 7 is a bearing, and 9 is a drive device.

Here, "dividing the circumference into two equal parts" means that, as is clear from FIG. It means to appear on the opposite side (or on the opposite side).

By arranging the two screw blades in this way, the pressure distribution of the sludge in the screw press is spread over the range from the sludge supply port 1 side to the dewatered cake discharge port 6 side, as shown in Fig. 6. As shown in the figure drawn by the pressure distribution curve C' shown in Fig. 3 and the outermost line (shown as a thick line) when this curve is superimposed by rotating it by 180 degrees around the center of the screw shaft 5. will be corrected. Therefore, it can be seen that the pressure distribution curve C obtained here has less unevenness than the pressure distribution curve C' for the conventional screw press.

That is, in the present invention, a tapered cone 8 is provided to increase the discharge resistance of the dehydrated cake and adjust the moisture content of the dehydrated cake, and a plurality of screw blades are used to adjust the unevenness of the pressure distribution curve. By easing the pressure, the advantages of the tapered cone can be effectively utilized, and the problem of shortened equipment life due to the provision of a tapered cone can be accurately solved, and furthermore, dehydration can be achieved even in the axially intermediate part of the screw press. Since a uniform squeezing force is applied to the sludge, a remarkable effect is obtained in that the sludge can be dewatered uniformly and efficiently.

Next, FIG. 7 shows another embodiment of the present invention.
The cross section corresponding to FIG. 5 above is shown, but in this example, the three screw blades 4a, 4b, and 4c divide the circumference of the screw shaft 5 into three equal parts, that is, each of these screw blades divides the circumference into three equal parts. The cross-sectional center lines are arranged at equal angles of 120° to each other.

It can be seen that the sludge pressure distribution curve in this case becomes as shown by the thick line in FIG. 8, which is even closer to a circle than the example in FIG. It goes without saying that the closer the pressure distribution curve is to a circle, the more equalized the pressure applied to the dehydrator will be.

In addition, in each of the above embodiments, each screw blade 4
a, 4b, etc., with substantially the same specifications as each other, but the pitches may be equal in the longitudinal direction of the screw shaft 5, or may be uneven (for example, from the sludge supply port 1 to the dewatered cake discharge port 6). It may also be possible to gradually decrease the size in the direction.

[Effect of idea]

As described above, the screw press type dehydrator of the present invention has a tapered cone near the dehydrated cake discharge port and a plurality of screw blades arranged in a predetermined manner on the screw shaft, so that the dehydrated cake can be removed easily. In addition to being able to adjust the moisture content,
The sludge pressure applied inside the dehydrator is equalized across the cross section perpendicular to the axis of the dehydrator, greatly reducing deformation of the screw shaft, outer cylinder, etc., minimizing wear and tear on the screw blades and outer cylinder, and improving the efficiency of the equipment. The vibration of the machine is also significantly reduced, making it possible to continue more stable dewatering operations for a longer period of time, greatly extending the life of the equipment, and efficiently obtaining a uniform dehydrated cake with a low water content, which also simplifies maintenance. There are practical benefits such as

[Brief explanation of the drawing]

Figure 1 is a longitudinal sectional view of the conventional example, Figure 2 is an enlarged view of the main parts of Figure 1, Figure 3 is a pressure distribution diagram of sludge in the screw press of Figure 1, and Figure 4 is the present invention. FIG. 5 is a cross-sectional view along the line of FIG. 4, FIG. 6 is a pressure distribution diagram of sludge in the screw press of FIG. 4, and FIG. 7 is a diagram of another embodiment of the present invention. FIG. 8 is a sectional view corresponding to FIG. 5 in the embodiment, and a pressure distribution diagram of the sludge in the screw press of FIG. 7. 1... Sludge supply port, 2... Hopper, 3... Outer cylinder, 4a, 4b... Screw blades, 5... Screw shaft, 6... Dehydrated cake discharge port, 7... Bearing, 8... Taper cone , 9... Drive device, 1
0'...Pressure detection port, C', C...Pressure distribution curve,
Pa...Maximum pressure, Pb...Minimum pressure.

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 material having a sludge supply port and a cake discharge port, and the sludge is compressed and dehydrated by rotation of the screw shaft and discharged from the cake discharge port. In the screw press type dehydrator, the gap between the outer surface of the screw shaft and the inner surface of the outer cylinder is configured to become smaller in the direction of the cake discharge port, and from one end on the supply port side to the other end on the discharge port side. A plurality of screw blades are installed on the screw shaft portion, and the height of each screw blade from the outer surface of the screw shaft is equal in any cross section perpendicular to the axis of the screw press, and the circumference of the screw shaft is equally divided by each screw blade. The screw press type dehydrator is arranged such that the cake is discharged, and a tapered cone is provided near the cake discharge port.