JPH08214B2 - Continuous discharge centrifuge - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a continuous discharge type centrifugal separator for separating a slurry into a separation sludge and a separated liquid, and particularly to a continuous discharge type centrifugal separator having an enhanced slurry precipitation effect. Regarding a centrifuge.

[Prior Art] A conventional counter-current type centrifugal separator as shown in Fig. 1 has a rotating ball 1 and a screw shaft 2 arranged on the same axis line inside thereof, A screw 3 is attached to the outer periphery of the shaft 2 in a spiral shape by welding or the like. A slurry injection pipe 2a is inserted into the screw shaft 2 from the left as viewed in the drawing.

Although the rotating ball 1 and the screw 3 rotate in the same direction, a speed difference (rotational speed difference) is provided between the rotating ball 1 and the screw 3. Therefore, the slurry supplied from the slurry inflow hole 6 into the rotating ball 1 is
The centrifugal force causes the radial sludge to flow in the radial direction, hit the inner peripheral surface 1a of the rotating ball 1, and separate into separated sludge and separated liquid. The separated sludge settles on the inner peripheral surface 1a of the rotating ball 1, is transferred to the left side 1b in FIG. 1 by the screw 3, is concentrated, and is discharged to the outside from the separated sludge discharge port 5 at one end of the rotating ball 1. . Further, the separated liquid overflows from the other end of the rotating ball 1, that is, the separated liquid discharge port 4 on the right side in FIG.

Besides the counter current method as shown in FIG.
Centrifugal separators that are variously devised such as the concurrent system are used. What these centrifuges have in common is that they have a structure with a rotating ball and a screw for scraping the separated sludge.

[Problems to be Solved by the Invention] With respect to a centrifugal separator having a structure including a screw, a problem to be solved by the present invention will be described.

Whatever the form of a centrifuge, the performance will not improve unless the separation sludge and the separation liquid are well balanced. Among the centrifugal separators, in the case of the centrifugal dehydrator, the solids recovery rate can be covered by the coagulant addition rate even if the separation sludge and the separation liquid are not well balanced. But,
In the case of a centrifugal concentrator that does not rely on the power of the flocculant, it does not rely on the power of the flocculant, so various measures must be taken to produce a clean separation liquid, that is, to increase the solid recovery rate. For example, in order to prevent a swirling flow that occurs in the cross-sectional direction in the flow channel, one or more rectifying plates are provided between the screw pitches to improve the separation performance.

However, in the conventional device, the blades of the screw and the current plate are perpendicular to the axis of the screw, and the slurry flowed in the radial direction by the blades of the screw inside the rotating ball is the inner peripheral surface of the rotating ball or the inner peripheral surface thereof. Solid-liquid separation will be performed only when the sludge accumulated on the surface is reached. In addition, a swirling flow 9 is generated in the flow path formed in the screw pitch in the rotating ball, which hinders sludge precipitation. Therefore, there was still a need for improvement in terms of precipitation effect.

[Means for Solving the Problem] A continuous discharge type centrifugal separator according to the present invention has a rotating ball provided with a slurry inflow hole, a separated sludge discharge port and a separated liquid discharge port, and the same inside the rotating ball. A centrifuge having a shaft arranged on the axis and a screw having blades extending in a radial direction from the shaft, and configured to rotate the rotating ball and the screw in the same direction with a differential speed. In the separator, in at least a part of the main solid-liquid separation portion, the blade of the screw is composed of a radially inner inclined portion and a radially outer scraped portion, the inclined portion being relative to the screw shaft. Tilted,
Extends most of the water depth of the main solid-liquid separation,
The scraping portion is oriented in a direction substantially orthogonal to the axis of the screw, and further has one or more screw-shaped straightening plates between the pitches of the screws in the main solid-liquid separation portion, wherein the straightening plate is Most of the water depth of the main solid-liquid separation part extends so as to be inclined with respect to the axis of the screw and at least partially overlap the blades of the screw in a direction orthogonal to the axis of the screw.

At least one of the inclined portion of the screw and the rectifying plate is preferably attached to the screw shaft via a root portion that is substantially orthogonal to the screw shaft. Further, it is preferable that the angle formed by the inclined portion of the screw and the axis of the screw is 30 to 60 degrees.

[Operation] In the continuous discharge centrifuge according to the present invention, most of the blades of the screw and the radial length of the straightening plate are inclined with respect to the axis of the screw, and the inclined portions at least partially overlap each other. Therefore, since the slurry hits the inclined part of the screw blade before reaching the inner peripheral surface of the rotating ball, the solid-liquid separation action is performed in a much shorter distance than the conventional type that does not have the inclined part, and the precipitation effect. Will increase.

[Example] The effect of the inclination of the screw blades on the solid-liquid separation of sludge will be described with reference to the drawings. The centrifugal separator of the example shown in FIG. A rotating ball 1 provided with an outlet 5 and a separated liquid discharge port 4, a screw shaft 2 arranged on the same axis line therein, and a screw 3 having a blade extending in a radial direction from the screw shaft 2; The rotating ball 1 and the screw 3 rotate in the same direction, and a speed difference is provided between the rotating ball 1 and the screw 3.

When the screw 3 is rotated, the slurry supplied from the slurry inflow hole 6 is caused to flow in the radial direction by the centrifugal force, collides with the inner peripheral surface 1a of the rotating ball and undergoes solid-liquid separation, and the sludge in the slurry is dispersed inside the slurry. The sediment is deposited on the peripheral surface, is transferred and concentrated in the direction of the left side 1b in the drawing by the screw 3, and is discharged from the separation sludge discharge port 5. Also, the separated liquid is
It passes through the flow path between the screws 3 and is overflowed and discharged from the separated liquid discharge port 4 provided in the rotating ball 1.

The screw 3 in FIG. 2 is an inclined screw. That is, the blade of the screw 3 has a scraping portion on the outer side in the radial direction.
3a and an inclined portion 3b on the inner side in the radial direction, the inclined portion 3b occupies most of the length of the blade, and is inclined with respect to the axis of the screw 3, that is, the axis 2. In other words,
Most of the blades of the screw 3 are inclined with respect to the axis of the screw, and the main solid-liquid separation is performed, that is, most of the water depth of the portion from the slurry inflow hole 6 to the separated liquid discharge port 4 is provided. It is growing. As a result, most sludge settles on the slope, slides down the slope, and accumulates on the inner surface of the ball, similar to the case where a slant plate is placed in the sedimentation basin. I understood. The inclination angle of the inclined portion 3b of the blade of the screw 3 is effective at 30 to 60 degrees with respect to the axis of the screw 3, and is preferably about 45 degrees. If it is less than 30 degrees, the blade strength of the screw 3 must be increased, and the carrying capacity of the precipitates will decrease, decreasing the overall processing capacity.
If it is higher than this value, the precipitation effect is not so much improved.
This angle should be determined by the properties of the sludge to be treated. The technical idea of inclining the blades of the screw in this way was not found in the prior art.

The blade scraping portion 3a of the screw 3 is oriented in a direction substantially perpendicular to the axis of the screw 3 in order to maintain the scraping effect.

In the centrifuge of the embodiment of the present invention shown in FIG. 3, one or more screw-shaped flow straightening plates 8 are provided between the pitches 7 of the screws 3 in the main solid-liquid separation portion. That is, one or more, preferably two straightening vanes 8 extend in the rotating ball 1 in the axial direction at the same pitch as the pitch 7 of the screws 3. As a result, the settled slurry always collides with the blades of the screw and the flow straightening plate, prevents swirling flow that may occur in the cross-sectional direction of the flow path, and enhances the precipitation effect by solid-liquid separation, resulting in a clean supernatant. Can be discharged as a separated liquid.

The straightening vane 8 is inclined substantially parallel to the inclined portion with respect to the axis of the screw and extends over most of the water depth of the portion where the main solid-liquid separation is performed.

The inclined portion of the straightening vane also has the same effect as the inclined portion of the screw blade. That is, the effect of separating and settling sludge is increased, similar to the case where a slant plate is placed in the settling tank. Also in this embodiment, the inclination angles of the inclined portion 3b of the blade of the screw 3 and the inclined portion 8a of the straightening plate 8 are 30 to 60 with respect to the axis of the screw 3.
There is an effect in degrees, and it is preferable that it is around 45 degrees.

In the embodiment shown in FIG. 3, the blades of the screw 3 and the current plate 8 are further attached to the attachment portion of the shaft 2 of the screw 3 via a member that is substantially orthogonal to the shaft 2 of the screw 3. That is, the blade of the screw 3 is composed of a scraping portion 3a, an inclined portion 3b and a root portion 3c, the inclined portion 3b occupies most of the length of the blade, and is inclined with respect to the axis of the screw 3. . Further, the current plate 8 is composed of an inclined portion 8a and a root portion 8b,
The inclined portion 8a is inclined with respect to the axis of the screw 3.

When installing the inclined plate type screw or inclined straightening plate, first attach the roots 3c, 8b in the direction perpendicular to the screw axis around the axis of the screw in the same way as a normal screw, and attach to the roots 3c, 8b. The inclined portion 3b of the screw 3 and the inclined portion 8a of the straightening vane 8 are attached. Then, the scraping portion 3a may be attached to the inclined portion 3b of the screw.

As described above, the one or more screw-shaped straightening vanes 8 are composed of the inclined portion 8a and the root portion 8b, but in the central portion of the pitch 7 of the screw 3, the cross-sectional direction of the flow channel (the direction perpendicular to the flow channel). It is important that it extends in the radial direction to the position where the swirling flow 9) of FIG. Specifically, the length of the straightening vane 8 in the radial direction is shorter than the blade of the screw 3, but must reach the position where the straightening vane 8 is immersed in the water depth of the rotating ball. Desirably, the length of the straightening vane 8 in the radial direction reaches about 1/2 or more of the water depth. This eliminates swirling flow in the cross-sectional direction of the flow path,
Since the separated sludge that has settled does not roll up, the separated liquid becomes clean and the solid recovery rate improves.

In addition, the base parts 3c and 8
b may or may not reach the water surface.

As described above, the generation of the swirl flow 9 (FIG. 1) cannot be suppressed unless the straightening vane 8 extends to the position where it is immersed in the water of the rotating ball, but conversely, when the straightening vane 8 is too long, that is, If the length of the baffle plate 8 exceeds about 1/2 or more of the water depth and comes into contact with the precipitated separation sludge or enters the separation sludge further, the slurry supply balance and the properties of the separation sludge and the separation liquid will be obtained. With respect to the uniformity of, there may be problems as in the double screw type.

On the other hand, in the embodiment of FIG. 3, the screw blades and the flow straightening plate overlap in a direction orthogonal to the axis of the screw in most of the area because the pitch of the screw blades is small. However, even if only a part of the screw vanes and the current plate are overlapped as in the state close to that of FIG. 2, the effect of colliding with the sludge settling can be sufficiently obtained.

The positions of the slurry inflow hole 6, the separated sludge discharge port 5, and the separated liquid discharge port 4 differ depending on the type of the centrifuge, and are not limited to the above-mentioned embodiments.

In the embodiment of FIG. 3, both the screw and the straightening vane are inclined, but in some cases, the effect of separation and precipitation can be improved by inclining only one of them. However, it is needless to say that it is desirable to incline both the screw and the current plate as in the embodiment of FIG. 3 from the viewpoint of the precipitation effect.

In the embodiment of FIGS. 2 and 3, the inclined plate type screw and the inclined straightening plate are provided over the main solid-liquid separation portion, that is, the portion from the slurry inflow hole 6 to the separated liquid discharge port 4. Alternatively, an inclined plate type screw or an inclined straightening plate may be provided in a part of the main solid-liquid separation portion.

[Effect] In the continuous discharge type centrifugal separator according to the present invention, most of the radial length of the inclined plate type screw is inclined with respect to the axis of the screw, so that the effect of separating and precipitating the slurry is remarkably improved. , Furthermore, since the screw type inclined rectifying plate is inclined with respect to the screw axis,
The separation and precipitation effect is further improved.

[Brief description of drawings]

FIG. 1 is a vertical sectional view showing a conventional centrifuge. FIG. 2 is a vertical cross-sectional view of a centrifuge in which the screw is inclined with respect to the axis to effectively perform solid-liquid separation of sludge. FIG. 3 is a vertical sectional view of an embodiment of the centrifuge of the present invention. 1 …… Rotating ball 1a …… Inner surface of rotating ball 1 ………… Screw shaft 3 …… Screw 3a …… Scraping part 3b …… Inclined part 3c …… Root part 4 …… Separated liquid discharge port 5 …… Separated sludge discharge port 6 …… Slurry inflow hole 7 …… Screw pitch 8 …… Rectifying plate 8a …… Sloping part 8b …… Root part 9 …… Swirl flow

Claims (3)

[Claims] 1. A rotating ball having a slurry inflow hole, a separated sludge discharge port, and a separated liquid discharge port, a shaft arranged on the same axis inside the rotating ball, and a blade extending radially from the shaft. In a centrifuge having a screw having, and configured to rotate the rotating ball and the screw in the same direction at a differential speed, at least a part of the main solid-liquid separation part , The blade of the screw is composed of an inclined portion on the radially inner side and a scraping portion on the outer side in the radial direction, the inclined portion is inclined with respect to the axis of the screw, and has a water depth of a portion for performing the main solid-liquid separation. Most of them extend, the scraping portion is oriented in a direction substantially orthogonal to the screw axis, and at the main solid-liquid separation part, one or more screw-like rectifiers are arranged between the screw pitches. The a, the rectifying plate, tilted with respect to the axis of the screw, so that at least partially overlap with the blades of the screw in the direction perpendicular to the axis of the screw,
A continuous discharge type centrifugal separator characterized in that most of the water depth of the main solid-liquid separation is extended. 2. The inclined portion of the screw and at least one of the straightening vanes are attached to the shaft of the screw via a root portion substantially orthogonal to the shaft of the screw.
The continuous discharge centrifuge described in. 3. The continuous discharge centrifuge according to claim 1, wherein the angle formed by the inclined portion of the screw and the axis of the screw is 30 to 60 degrees.