JP7457470B2 - centrifugal separator - Google Patents

Description

The present disclosure relates to a centrifugal separator that centrifugally separates solids and liquids from a mixture of solids and liquids.

Patent Document 1 discloses a centrifugal separator that centrifugally separates solids and liquids by centrifugation. This centrifugal separator comprises an inner and an outer cylinder having the same axis of rotation. The mixture to be centrifuged passes through the inner cylindrical body and is discharged from the outlet of the inner cylindrical body into the outer cylindrical body. This mixture is centrifuged within the outer cylindrical body, and the liquid separated from the solid forms a liquid layer that rotates following the inner peripheral surface of the outer cylindrical body. For example, a new mixture is ejected from the inner cylindrical body at the same rotational speed as the outer cylindrical body, and this new mixture is centrifuged while rotating in the same direction as the outer cylindrical body. It also moves in this direction and mixes into the liquid layer.

JP2009-136790A

However, the further away from the center of rotation the mixture released in the centrifugal direction from the rotating inner cylinder is, the slower its speed in the direction of rotation becomes, and when it is mixed into the liquid layer, the difference in rotational speed between the liquid layer and the mixture is likely to become large. As a result, this difference in rotational speed can disturb the liquid layer, potentially impairing the solid-liquid separation ability that separates solids from liquid.

An object of the present disclosure is to provide a centrifugal separator that is advantageous for stably maintaining a liquid layer separated from a solid and that does not easily impair solid-liquid separability.

A centrifugal separator according to one aspect of the present disclosure includes a cylindrical outer body that accommodates a mixture of a solid and a liquid and centrifugally separates the solid and liquid from the mixture by rotation; The inner barrel is arranged along the rotational axis of the inner barrel and rotates in the same direction as the rotational direction of the outer barrel while transferring the mixture. a screw blade for transferring solids to one side along the inner barrel; the inner barrel includes a discharge port for discharging the internal mixture between the inner circumferential surface of the outer barrel and the inner barrel; is arranged facing forward in the direction of rotation with reference to the discharge direction of the mixture.

According to this centrifugal separator, the mixture inside the inner barrel is discharged forward in the rotational direction through the discharge port. Therefore, the velocity in the rotational direction is substantially increased compared to the embodiment in which the material is discharged in the centrifugal direction. As a result, it becomes easier to reduce the speed difference in the rotational direction when the mixture is mixed into the liquid layer.

In some embodiments, the screw blades are spirally provided on the outer circumferential surface of the inner body, the discharge port is provided between the pitches of the screw blades, and the direction of discharge of the mixture is in the spiral direction of the screw blades. It can be in the same direction. According to this aspect, since the mixture discharged from the discharge port flows along the screw blades, it is less likely to be interfered with by the screw blades, and therefore the speed in the rotation direction is less likely to decrease.

In some embodiments, a liquid layer in which solids are separated from the mixture is formed in a region along the inner circumferential surface of the outer body, and the outlet is located further outside than at the interface between the liquid layer and the gas region. It can be provided in a position away from the inner circumferential surface of the trunk. According to this aspect, the mixture is indirectly mixed into the liquid layer via the gas region, making it difficult to directly influence the solid-liquid separability within the liquid layer.

In some embodiments, a liquid layer in which solids are separated from the mixture is formed in a region along the inner peripheral surface of the outer body, and the discharge port is disposed within the liquid layer. can. According to this aspect, the mixture is directly discharged in the forward direction of rotation within the liquid layer. As a result, the speed difference in the rotational direction that occurs with the liquid layer becomes smaller.

According to some aspects of the present disclosure, it is advantageous to stably maintain a liquid layer separated from a solid, and solid-liquid separability is not easily impaired.

FIG. 1 is a perspective view showing a screw decanter type centrifugal separator according to an embodiment. FIG. 2 is a longitudinal cross-sectional view showing the internal structure of the outer bowl and inner screw conveyor according to the embodiment. FIG. 3 is a schematic cross-sectional view taken along line III--III in FIG. 2. FIG. 4 is an enlarged side view of a portion of the inner screw conveyor. FIG. 5 corresponds to FIG. 3 and is a sectional view of an inner barrel screw conveyor according to another embodiment. FIG. 6 shows a centrifugal separator according to Example 1, and (a) is an explanatory diagram showing the state of swirl when the inside of the outer barrel bowl and the inner barrel screw conveyor is viewed from the rotation axis direction, (b) is an explanatory diagram showing the state of liquid flow within the liquid layer. FIG. 7 shows a centrifugal separator according to Comparative Example 1, in which (a) is a vertical sectional view showing the internal structure of a part of the outer bowl and the inner screw conveyor, and (b) is a vertical cross-sectional view showing the internal structure of a part of the outer bowl and the inner screw conveyor. It is an explanatory view showing the state of swirl when the inside of the trunk bowl and the inner trunk screw conveyor are viewed from the rotation axis direction, and (c) is an explanatory diagram showing the state of the flow of liquid in the liquid layer. FIG. 8 is a graph showing the solid particle recovery rate (separation efficiency) in Example 2 and Comparative Examples 2 and 3.

Hereinafter, embodiments of the centrifugal separator will be described in detail with reference to the drawings. In addition, in the description of the drawings, the same elements or corresponding elements may be given the same reference numerals, and redundant description may be omitted.

A centrifugal separation process is used as a solid-liquid separation process to separate a mixture of a heavy solid (solid) and a light liquid (hereinafter referred to as "undiluted solution"). In the centrifugal separation process, for example, the stock solution is rotated at high speed in a rotating body, and solid-liquid separation is promoted by increasing the sedimentation rate of the solid by the radial centrifugal force applied to the rotating body. In this embodiment, a screw decanter type centrifugal separator will be described as an example of a device that implements this centrifugal separation process.

As shown in FIGS. 1 and 2, the centrifugal separator 1 includes a rotating body 2, which is the main part for realizing centrifugal separation, a casing 5 that houses the rotating body 2, and a desired rotational force applied to the rotating body 2. The rotary body 2 is provided with a drive unit 6 for applying the liquid, and a feed pipe 7 for supplying the stock solution M into the rotating body 2. The centrifugal separator 1 is used in various fields such as manufacturing processes of foods, drinking water, medicines, chemical products, steel products, etc., and water treatment such as human waste treatment, sewage treatment, slurry treatment, and factory wastewater treatment. Used for separation. It can also be used for solid-liquid separation of objects to be processed, such as bacterial cells and microorganisms, where it is desired to avoid impacting solids as much as possible.

The rotating body 2 includes an outer bowl 3 (outer barrel) and an inner screw conveyor 4 disposed within the outer bowl 3. The rotational direction Ra of the outer bowl 3 (see FIG. 3) and the rotational direction Ra of the inner screw conveyor 4 are the same. The outer bowl 3 is a substantially cylindrical body, and shaft portions at both ends are rotatably supported by bearings 3a. The main part of the outer body bowl 3 is arranged inside the casing 5. The rotational axis L of the outer bowl 3 extends in the longitudinal direction of the outer bowl 3 so as to pass through both bearings 3a. The outer bowl 3 accommodates the stock solution M therein, rotates under the action of the drive unit 6, and centrifugally separates the stock solution M into a liquid Lq and a solid Sd (see FIG. 3).

As shown in FIG. 2, one end of the outer bowl 3 in the rotational axis direction (direction along the rotational axis L) is gradually reduced in diameter, and this diameter reduction forms a constricted portion 31. There is. The throttle part 31 is provided with a solid discharge port 32 for discharging the solid Sd conveyed by the inner screw conveyor 4. A small-diameter outer barrel shaft 33 that seals (closes) the outer barrel bowl 3 is fixed to one end of the outer barrel bowl 3 . The small-diameter outer barrel shaft 33 is rotatably supported by an external bearing 3a (see FIG. 1). A feed pipe 7 is arranged at the center of the small diameter outer barrel shaft 33 so as to pass through the small diameter outer barrel shaft 33. The feed pipe 7 extends along the rotation axis L of the outer bowl 3 and is supported by a feed pipe holder 7a. The stock solution M supplied to the outer bowl 3 passes through the feed pipe 7 . An inner screw conveyor 4 is arranged so as to partially surround the feed pipe 7. The inner screw conveyor 4 and the small-diameter outer shaft 33 of the outer bowl 3 are rotatably connected via a bearing 34.

A large-diameter outer barrel shaft 35 is provided at the other end of the outer barrel bowl 3 in the rotational axis direction. The large-diameter outer barrel shaft 35 has an annular inner wall portion 35a that seals (closes) a space between the outer barrel bowl 3 and the inner barrel screw conveyor 4, and a ring-shaped inner wall portion 35a that extends from the center portion of the inner wall portion 35a to the outer barrel bowl 3. It includes an inner shaft portion 35b that projects inward, and an outer shaft portion 35c that projects outward from the outer body bowl 3 from the center portion of the inner wall portion 35a. A bearing 35d for pivotally supporting the inner screw conveyor 4 is attached to the inner shaft portion 35b. The outer shaft portion 35c is rotatably supported by an external bearing 3a (see FIG. 1). A plurality of liquid passage ports 36 are provided at positions on the outer side of the inner wall portion 35a in the centrifugal direction CD, through which the liquid Lq separated from the solid Sd in the liquid layer passes and is discharged. The plurality of liquid passage ports 36 are provided along the inner circumferential surface 3b of the outer bowl 3.

The inner body screw conveyor 4 includes an inner body 41, which is a cylindrical body having a substantially cylindrical shape, and a screw blade 42 provided on the outer peripheral surface 41a of the inner body 41 and protruding radially outward. The inner body 41 rotates in the same direction as the rotation direction Ra of the outer body bowl 3. The screw blade 42 is provided spirally wound on the outer peripheral surface 41a of the inner body 41. The screw blade 42 rotates with the rotation of the inner body 41, and transfers the solid Sd centrifuged from the liquid Lq to one end side of the inner body 41. The one end side of the inner body 41 is reduced in diameter to correspond to the reduced diameter of the outer body bowl 3. One end of the inner body 41 is connected to the feed pipe 7 and the outer body bowl 3 via a bearing 34 so as to be freely rotatable.

The peripheral wall 43 of the inner body portion 41 is provided with a passage port 8 through which the stock solution M passes, and a stock solution guide portion 9 that interferes with the stock solution M that has passed through the passage port 8 and changes the discharge direction of the stock solution M. The stock solution guide portion 9 is formed with a discharge port 91 for releasing the stock solution M between the inner peripheral surface 3b of the outer barrel bowl 3 and the inner barrel portion 41, and a stock solution flow path 92. The raw solution flow path 92 is curved from the passage port 8 and connected to the discharge port 91, and connects the passage port 8 and the discharge port 91.

The raw solution guide portion 9 may be welded to the outer circumferential surface 41a of the inner body portion 41, or may be formed integrally with the inner body portion 41. Furthermore, since there is a concern that the stock solution guide section 9 may be worn out by fixed particles in the stock solution M, the stock solution guide section 9 may be replaced with respect to the inner body section 41 to have a replaceable structure (for example, a bush). It is.

The stock solution M to be centrifuged passes through the feed pipe 7 and is supplied into the inner barrel 41, and then passes through the passage port 8 of the inner barrel 41 and the stock solution channel 92 to the discharge port 91. released from. The stock solution M supplied into the outer bowl 3 from the discharge port 91 is centrifuged into a liquid Lq and a solid Sd by the rotation of the outer bowl 3. The liquid Lq from which the solid Sd has been separated forms a liquid layer LL that rotates following the inner circumferential surface 3b of the outer bowl 3. To explain in more detail, of the stock solution M, the heavy component, solid Sd (mainly solid particles), is accumulated so as to be deposited on the inner circumferential surface 3b of the outer bowl 3, and the light component, liquid Lq, is accumulated as follows. The liquid layer LL is mainly present inward of the solid Sd (in a direction opposite to the centrifugal direction CD). The surface layer surface of the liquid layer LL, that is, the surface formed inward of the liquid layer LL is a boundary surface Bs between the gas region As and the liquid layer LL, where the solid Sd and the liquid Lq are sparse.

The inner screw conveyor 4 transfers the solid Sd that has settled in the liquid layer LL in the centrifugal direction CD and has been deposited on the inner circumferential surface 3b of the outer bowl 3 to one end side of the outer bowl 3 using the screw blade 42. send. A constriction section 31 is provided on one end side, and solid Sd is dehydrated by interaction between the constriction section 31 and the screw blade 42 and discharged from the solid discharge port 32 .

An inner wall portion 35a is provided at the other end of the outer body bowl 3, and a liquid passage port 36 is provided in the inner wall portion 35a. The liquid Lq forming the liquid layer LL passes through the liquid passage port 36 of the inner wall portion 35a and is discharged to the outside. At least a portion of the liquid passage port 36 is closed by an orifice plate 37. To explain in more detail, the orifice plate 37 blocks a part of the entire area of the liquid passage port 36 on the side closer to the inner circumferential surface 3b of the outer body bowl 3. As a result, the thickness of the liquid layer LL, in other words, the height from the inner circumferential surface 3b of the outer bowl 3 to the boundary surface Bs of the liquid layer LL is determined by the height of the orifice plate 37. The height of the orifice plate 37 is substantially from the position closest to the inner circumferential surface 3b of the outer bowl 3 to the inner circumferential surface 3b of the partial area of the liquid passage port 36 blocked by the orifice plate 37. means the distance.

The drive unit 6 includes a drive motor 61 that rotates the outer bowl 3 in one direction and provides the outer bowl 3 with a centrifugal separation function. The outer bowl 3 is rotated at a high speed of, for example, 10 rpm to 10,000 rpm by a driving motor 61. Further, the drive unit 6 includes a differential speed brake 62 that rotates the inner screw conveyor 4, a planetary gear mechanism of a gear box 63, and the like. The inner barrel portion 41 of the inner barrel screw conveyor 4 is rotated at high speed in the same direction as the outer barrel bowl 3 by the power of the differential speed brake 62 and the planetary gear mechanism of the gear box 63. The rotational speed difference between the inner body portion 41 and the outer body bowl 3 is 50 rpm or less. This rotational speed difference can be 15 rpm or less, 10 rpm or less, or 5 rpm or less.

Next, the orientation of the stock solution guide section 9 and the discharge port 91 will be explained with reference to FIGS. 2, 3, and 4. The stock solution guide portion 9 is a cylindrical body having a substantially semicircular cross section, and is provided so as to be oriented laterally along the tangential direction of the outer circumferential surface 41a of the inner barrel portion 41. One end of the stock solution guide section 9 is curved and closed, and a discharge port 91 is provided at the other end. The internal space serving as the stock solution flow path 92 of the stock solution guide section 9 communicates with the passage port 8 of the inner barrel section 41 on one end side, and communicates with the discharge port 91 on the other end side.

The discharge port 91 is arranged so as to face forward in the rotational direction Ra of the inner barrel 41 with reference to the discharge direction Da of the stock solution M. In this embodiment, "rotation direction Ra of the inner barrel portion 41" means the rotation direction Ra of the inner barrel screw conveyor 4, and is the same direction as the rotation direction Ra of the outer barrel bowl 3. Furthermore, even when the inner screw conveyor 4 is in a stationary state, observing the spiral shape of the screw blades 42 shows that the solid Sd is on one end side of the outer body bowl 3 (the constriction part 31 side). The rotational direction Ra in which the image is sent can be specified. That is, the rotational direction Ra specified based on the helical shape of the screw blade 42 is the rotational direction Ra of the inner barrel portion 41. Next, "based on the discharge direction Da of the stock solution M" means that the direction of the discharge port 91 is defined based on the discharge direction Da of the stock solution M discharged from the discharge port 91. As a result, the release direction Da of the stock solution M that passes through the substantially central portion of the release port 91 and is released is substantially in the direction of the release port 91 . Note that if a plane including the periphery (for example, circular) of the discharge port 91 can be assumed, the normal direction of this plane can be defined as the orientation of the discharge port 91.

Further, "facing forward in the rotational direction Ra of the inner body section 41" means that the discharge direction Da or the normal direction is substantially the front side in the rotational direction Ra. Further, assuming a reference plane Px passing through the rotation axis L and the center of the discharge port 91, and distinguishing between a region Qx on the forward rotation side and an region Qy on the reverse rotation side in the rotation direction Ra with this reference plane Px in between, , "Front in the rotation direction Ra" means to broadly include the region Qx on the normal rotation side. Therefore, "facing forward in the rotation direction Ra of the inner body section 41" means, for example, not only the normal direction of the reference plane Px facing the normal rotation side region Qx, but also the direction tilted with respect to this normal direction. It may be a direction.

The concentrate guide part 9 is provided between pitches Pd of the screw blades 42, and the longitudinal direction of the concentrate guide part 9 is arranged along the helical direction of the screw blades 42. Therefore, the discharge direction Da of the stock solution M according to this embodiment is along the helical direction of the screw blade 42. Note that the discharge direction Da of the stock solution M is not limited to the direction along the helical direction of the screw blade 42, but broadly includes directions non-parallel to the rotation axis direction, for example, a direction perpendicular to the rotation axis direction. Also good.

The top 9a of the concentrate guide 9 is located at the farthest position from the outer peripheral surface 41a of the inner body 41. In this embodiment, the top 9a of the concentrate guide 9 is not buried in the liquid layer LL, and the discharge port 91 is located at a position farther from the inner peripheral surface 3b of the outer body bowl 3 than the boundary surface Bs of the liquid layer LL. To add a little more about the boundary surface Bs of the liquid layer LL, the boundary surface Bs is determined, for example, by the position 36a of the periphery of the liquid passage port 36 that is closest to the inner peripheral surface 3b of the outer body bowl 3. The distance d2 from the boundary surface Bs determined based on this position 36a to the inner peripheral surface 3b of the outer body bowl 3 is shorter than the distance d1 from the top 9a of the concentrate guide 9 to the inner peripheral surface 3b of the outer body bowl 3.

Next, the functions and effects of the centrifugal separator 1 according to this embodiment will be explained. In the centrifugal separator 1, the stock solution M discharged forward in the rotational direction Ra from the discharge port 91 of the stock solution guide section 9 moves in the centrifugal direction CD while changing its trajectory, and mixes into the liquid layer LL.

Here, for example, assume a form (comparative form) in which the stock solution guide portion 9 is not provided and the stock solution M is discharged from the passage port 8 in the centrifugal direction CD. In the comparative embodiment, the stock solution M discharged from the passage port 8 of the inner barrel 41 has a rotational speed vθb. This stock solution M reaches the boundary surface Bs of the liquid layer LL at a rotational speed of vθb while moving in the centrifugal direction CD. On the other hand, the liquid layer LL rotates following the rotation of the outer body bowl, and it can be assumed that the boundary surface Bs of the liquid layer LL has a rotational speed vθa corresponding to the rotational speed of the outer body bowl. As a result, the difference between the rotational speed vθa of the boundary surface Bs of the liquid layer LL and the rotational speed vθb of the stock solution M becomes large.

In contrast, in the present embodiment, the stock solution M is discharged from the discharge port 91 toward the front side in the rotational direction Ra, so that the speed (rotational speed) in the rotational direction Ra can be easily increased. As a result, compared to the comparative embodiment, when the stock solution M mixes into the liquid layer LL, it becomes easier to reduce the difference in rotational speed that occurs between the stock solution M and the liquid layer LL.

The concentrate guide section 9 is provided between the pitches Pd of the screw blades 42, and the discharge direction Da of the concentrate M is along the spiral direction of the screw blades 42. As a result, the concentrate M discharged from the discharge port 91 flows along the screw blades 42 and is less likely to be interfered with by the screw blades 42, so the rotation speed is less likely to decrease.

Further, the discharge port 91 is provided at a position farther from the inner circumferential surface 3b of the outer body bowl 3 than the boundary surface Bs, and the stock solution M discharged from the discharge port 91 indirectly passes through the gas region As. Therefore, the liquid layer LL is mixed with the liquid layer LL. As a result, the stock solution M discharged from the discharge port 91 becomes difficult to directly influence the solid-liquid separability within the liquid layer LL. As a result, it is possible to reduce the possibility that solid particles that are settling in the centrifugal direction CD or solid Sd that has already settled and accumulated in the liquid layer LL will be thrown up, and to suppress the decline in solid-liquid separability. There is.

Further, for example, when the processed material such as bacterial cells and microorganisms that is to be treated with as little impact as possible on the solid Sd is the stock solution M, according to the centrifugal separator 1 according to the present embodiment, the rotation of the stock solution M and the liquid layer LL is Since the difference in speed can be reduced, the impact on the solid Sd can be softened, which is advantageous.

In addition, in the centrifugal separator 1 according to the present embodiment, the difference in rotational speed between the stock solution M and the liquid layer LL can be reduced without reducing the rotational speed of the outer bowl 3, so that the centrifugal force required for solid-liquid separation can be reduced. becomes easier to maintain or increase.

On the other hand, as shown in FIG. 5, as another embodiment, the discharge port 91 may be arranged within the liquid layer LL. A centrifugal separator 1A according to another embodiment has the same structure and elements as the centrifuge 1 according to the above-described embodiment, and similar structures and elements are given the same reference numerals and detailed explanations will be omitted. This will be omitted and the explanation will focus on the differences.

The centrifuge 1A is provided with a stock liquid guide section 9A that is erected in the centrifugal direction CD from the outer peripheral surface 41a of the inner body 41 toward the inner peripheral surface 3b of the outer body bowl 3. The stock liquid guide section 9A is provided with a discharge port 91 and a stock liquid flow path 92, and the stock liquid flow path 92 is connected to the passage port 8 and the discharge port 91 of the inner body 41. The discharge port 91 is disposed in the liquid layer LL. The discharge port 91 is also disposed so as to face forward in the rotation direction Ra of the inner body 41 based on the discharge direction Da of the stock liquid M.

According to the centrifugal separator 1A of this embodiment, the raw liquid M is discharged forward in the rotation direction Ra through the discharge port 91. Therefore, the rotation speed is substantially increased compared to the case where the raw liquid M is discharged in the centrifugal direction CD. As a result, it becomes easier to reduce the speed difference in the rotation direction Ra when the mixture is mixed into the liquid layer LL. In particular, in this embodiment, the discharge port 91 is disposed in the liquid layer LL, and the raw liquid M is directly discharged forward in the rotation direction Ra within the liquid layer LL. As a result, the speed difference in the rotation direction Ra that occurs between the raw liquid M and the liquid layer LL is reduced.

The centrifugal separator 1, 1A according to the present disclosure has been described above based on the embodiment and other embodiments. However, the present disclosure is not limited to only the above-mentioned embodiment. For example, the above-mentioned embodiment has been described using the concentrate guide section 9, 9A in which the orientation and height of the discharge port 91 are fixed, but the discharge port 91 may be structured so that the orientation and height are adjustable (e.g., extendable).

EXAMPLES Hereinafter, the present disclosure will be explained in more detail with reference to examples, but the present disclosure is not limited to these examples. Further, in Examples and Comparative Examples to be described later, the same elements and corresponding structures as in the above-described embodiment may be given the same reference numerals as in the above-described embodiment, and the description thereof may be omitted.

(Example 1, Comparative Example 1)
Embodiment 1 (see FIG. 6) has a structure corresponding to the above-described embodiment, and the inner barrel portion 41 of the inner barrel screw conveyor 4 has grooves arranged at equal intervals in the circumferential direction when viewed from the rotational axis direction. A plurality of (four) passage ports 8, a stock solution guide section 9, and a discharge port 91 are provided so as to be as follows. The inner diameter of the passage port 8 and the discharge port 91 is 100 mm. The stock solution M passes through the discharge port 91 and is discharged at a flow rate of 3 m ³ /h. The rotational speed difference between the outer bowl 3 and the inner barrel portion 41 of the inner screw conveyor 4 was 10 rpm.

Comparative Example 1 (see FIG. 7) is substantially the same as Example 1 except that it does not include the stock solution guide section 9 provided with the discharge port 91.

(b) of FIG. 6 is a diagram showing the state of swirl when the inside of the outer body bowl 3 and the inner body 41 according to the first embodiment is viewed from the rotational axis direction; a) A diagram schematically showing the relative flow direction and size in the liquid layer LL with respect to the outer body bowl 3 in the liquid layer LL in the region X in the figure. In addition, in the figure (b), the arrow extending toward the left side with respect to the area It means the size of backflow.

7(a) is a partially enlarged sectional view of the outer bowl 3 and inner barrel 41 according to Comparative Example 1, and FIG. 7(b) is an enlarged cross-sectional view of the outer bowl 3 and inner barrel 41. It is an explanatory view showing the state of the swirl when the inside is viewed from the rotational axis direction, and (c) is an explanatory diagram showing the state of the swirl when the inside is viewed from the rotation axis direction. FIG. 3 is a diagram schematically showing the relative flow direction and magnitude. In addition, in the figure (b), the arrow extending toward the left side with respect to the area Y means that the flow is relatively reverse to the speed in the rotation direction Ra of the outer body bowl 3, and the length of the arrow is It means the size of backflow.

As shown in FIG. 6(a), in Example 1, the stock solution M discharged from the discharge port 91 of the stock solution guide section 9 changes its trajectory toward the centrifugal direction CD so as to curve, and It is mixed so as to be substantially orthogonal to the boundary surface Bs of the layer LL. As shown in FIG. 6B, in the first embodiment, the rotational speed of the liquid layer LL near the boundary surface Bs is relatively opposite to the rotational speed of the outer body bowl 3. However, the direction of the flow is relatively stable, and this is effective in stably maintaining the liquid layer LL.

On the other hand, as shown in FIG. 7(b), in Comparative Example 1, the stock solution M that has passed through the passage port 8 of the inner body portion 41 is mixed obliquely with respect to the boundary surface Bs of the liquid layer LL. ing. As shown in FIG. 7(c), the flow direction near the boundary surface Bs of the liquid layer LL in Comparative Example 1 is more turbulent than in Example 1 (see FIG. 6(b)). is large. Further, the rotational speed of the liquid layer LL in the vicinity of the boundary surface Bs of Comparative Example 1 is relatively opposite to the rotational speed of the outer body bowl 3. The magnitude of this backflow is larger than that in Example 1, which may be detrimental to the solid-liquid separability.

(Example 2, Comparative Example 2, Comparative Example 3)
FIG. 8 is a graph showing the solid particle recovery rate (separation efficiency). Embodiment 2 is a device in which a stock solution guide portion 9 with a height of 40 mm is provided in an inner body portion 41 with an inner diameter of 100 mm, and a discharge port 91 is oriented toward the front in the rotation direction Ra. Comparative Example 2 is a device substantially common to Example 2, except that it does not include the stock solution guide section 9. Comparative Example 3 is a device in which the discharge port 91 is oriented toward the rear (reverse rotation side) in the rotation direction Ra.

As shown in FIG. 8, in Example 2, the solid particle recovery rate is improved compared to Comparative Examples 2 and 3.

1, 1A Centrifugal separator 3 Outer barrel bowl (outer barrel)
3b Inner peripheral surface 91 Discharge port 41 Inner barrel 42 Screw blade Bs Boundary surface As Gas region CD Centrifugal direction Da Discharge direction Ra Rotational direction LL Liquid layer Sd Solid Lq Liquid Pd Pitch distance M Stock solution (mixture)
L Rotation axis

Claims (4)

a cylindrical outer body that contains a mixture of solids and liquids and that separates the solids and the liquid from the mixture by centrifugal separation;
an inner body portion disposed inside the outer body portion along a rotation axis of the outer body portion, for transferring the mixture and rotating in the same direction as the rotation direction of the outer body portion;
A screw blade is provided on an outer circumferential surface of the inner body portion and transports the solid to one side along the rotation axis of the inner body portion,
The inner body portion includes a passage port through which the mixture passes, a discharge port that discharges the mixture that has passed through the passage port between an inner circumferential surface of the outer body portion and the inner body portion, and a mixture flow path that communicates with the passage port and the discharge port,
The discharge port is disposed forward of the passage port in the direction of rotation and faces forward in the direction of rotation based on the discharge direction of the mixture,
the mixture flow path is connected to the passage port so as to surround the entire circumference of the passage port, curves at a portion connected to the passage port and on the way from the passage port to the discharge port, and extends in a direction along the helical direction of the screw blade to communicate with the discharge port. The discharge port is provided between the pitches of the screw blades,
2. The centrifugal separator according to claim 1, wherein the direction of discharge of the mixture is along the helical direction of the screw blade. A liquid layer in which the solid is separated from the mixture is formed in a region along the inner peripheral surface of the outer body,
The centrifugal separator according to claim 1 or 2, wherein the discharge port is provided at a position farther from the inner circumferential surface of the outer body than the interface between the liquid layer and the gas region. A liquid layer in which the solid is separated from the mixture is formed in a region along the inner peripheral surface of the outer body,
The centrifugal separator according to claim 1 or 2, wherein the discharge port is located within the liquid layer.

Images