Drum-type thickener

Abstract

To provide a drum-type concentrator capable of promoting solid-liquid separation of mud transferred to a screw blade in a concentration chamber.SOLUTION: A concentrator for separating a filtering liquid from an outer cylindrical screen 2 while transferring mud in a concentration chamber 7 by a screw blade 3 and discharging the concentrated mud through an outlet 11 of the concentration chamber 7 comprises a slide-contact rake 22 including a bridge member 23 which is fixed to the front and rear of the screw blade 3 in the axial core direction of a screw shaft 4 and through an outlet 31 of which formed with a prescribed gap partial mud is discharged in a ridge shape, and a slide-contact member 24 fixed to a side close to the outer cylindrical screen 2 of the bridge member 23 and slid into contact with the inner surface of the outer cylindrical screen 2. The mud deposited in the concentration chamber is raked in a ridge shape by the slide-contact rake 22 to promote concentration work of the mud.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an improvement in a drum thickener that separates filtrate from an external cylindrical screen while transporting sludge generated from wastewater treatment facilities such as sewage, human waste, rural wastewater, and factories using screw blades. [Background technology]

[0002] Conventionally, a drum-type thickener has been known in which a screw shaft is rotatably inserted into a cylindrical screen, sludge supplied inside is transported by the screw shaft, solid-liquid separation is performed by the screen, and the thickened sludge is discharged from a discharge outlet.

[0003] Patent Document 1 discloses a vertical filtration concentration apparatus having a plate-shaped scraping member that is biased toward the outer periphery of the screw and is attached so as to be in sliding contact with the inner periphery of the filter screen, spanning between the screw blades.

[0004] Patent Document 2 discloses a clogging removal device in which comb-like scrapers that engage with slits in a screen made of a large number of wire rods arranged in parallel in a trough shape are provided on the outer periphery of a spiral blade. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2017-000910 [Patent Document 2] Japanese Utility Model Application Publication No. 05-093679 Summary of the Invention [Problem to be solved by the invention]

[0006] In conventional technology, sludge supplied to a thickener accumulates at the bottom of a drum-type screen and is transported by screw blades parallel to the central axis, making it difficult for the water inside the sludge to be discharged from the screen.

[0007] In the technology of Patent Document 1, sludge is transported toward the discharge outlet by scraping members that rotate together with the screw blades, while sliding inside the screen. When this technology is applied to a horizontal drum-type thickener, the sludge that has accumulated at the bottom is lifted to a certain height by the scraping members and then dropped back to the bottom, which raises concerns that the weak thickened flocs will break down and some of the solids will pass through the screen, resulting in a decrease in the solids recovery rate.

[0008] Furthermore, because the plate-shaped blade is in sliding contact with the screen over its entire length, all of the sludge is scraped off by the scraping member. Although pressure is applied during scraping, the sludge is densely packed on the surface of the scraping member, so the moisture inside the sludge rarely escapes to the outside. Furthermore, if the height of the scraping member is low, some of the sludge will climb over the scraping member and fall to the backside of the scraping member. While moisture can be discharged from the bottom of the fallen sludge, the moisture exposed on the top surface cannot be discharged because the sludge gets in the way. Furthermore, the sludge does not rotate much, resulting in low solid-liquid separation efficiency.

[0009] In the technology of Patent Document 2, sludge accumulated at the bottom of a screen is scraped off with a comb-shaped scraper, but the comb-shaped scraper is designed to engage with the slits of the screen, which is made up of many wire rods arranged in parallel like a trough. Only the action of scraping up and transporting the sludge is described, and it is recognized that the entire amount of accumulated sludge is scraped up, so there is a risk that the thickened flocs will break down as the sludge falls.

[0010] The present invention provides a drum-type thickener in which sliding rakes, through which sludge can pass, are provided along the central axis at regular intervals between the pitches of the screw blades, and which improves thickening performance by the scraping effect of the inner surface of the screen and the rolling effect of the sludge. [Means for solving the problem]

[0011] The present invention relates to a concentrator in which a concentration compartment is formed by an external cylindrical screen and a screw shaft around which screw blades are wound, and filtrate is separated from the external cylindrical screen while the sludge in the concentration compartment is transported by the screw blades, and the concentrated sludge is discharged from the outlet of the concentration compartment. and a bridge member. a sliding contact member fixed to an edge of the bridging member adjacent to the outer cylindrical screen and in sliding contact with the inner surface of the outer cylindrical screen; an outlet formed by a recess in a bridge member formed unevenly so that a near side or a far side of the outer cylindrical screen has a predetermined gap, and through which a portion of the sludge is discharged in a ridge-like shape; The sludge scraped aside by the sliding rake is discharged from the outlet in a ridge-like shape while rolling, increasing the surface area of ​​the accumulated sludge and making it easier for the liquid inside to drain out. At the same time, the recessed portion acts as an outlet, making it easier to discharge sludge. It is something.

[0014] In addition, in a concentrator in which a concentration chamber is formed by a screw shaft around which an external cylindrical screen and screw blades are wound, filtrate is separated from the external cylindrical screen while the sludge in the concentration chamber is transported by the screw blades, and concentrated sludge is discharged from the outlet of the concentration chamber, the concentrator is provided with a sliding rake composed of a bridge member fixed to the front and back of the screw blades along the axial direction of the screw shaft, a sliding member fixed to the edge of the bridge member close to the external cylindrical screen and in sliding contact with the inner surface of the external cylindrical screen, and an outlet formed between the pitches of the spiral blades of the spirally formed bridge member and from which a portion of the sludge is discharged in a ridge-like shape. This prevents the sludge from falling due to the scraping action, and allows the thickened flocs to be maintained firmly.

[0015] In a concentrator in which a concentration chamber is formed by a screw shaft around which an external cylindrical screen and screw blades are wound, filtrate is separated from the external cylindrical screen while the sludge in the concentration chamber is transported by the screw blades, and concentrated sludge is discharged from the outlet of the concentration chamber, the concentrator is provided with a sliding rake consisting of: a bridge member fixed to the front and back of the screw blade along the axial direction of the screw shaft; a sliding member fixed to the edge of the bridge member close to the external cylindrical screen and in sliding contact with the inner surface of the external cylindrical screen; and an outlet formed between adjacent protrusions by twisting or tilting certain protrusions of the bridge member formed with multiple protrusions, and through which some sludge is discharged in a ridge-like shape. This makes the material easier to process and reduces costs. [Effects of the Invention]

[0016] The present invention uses a sliding rake to push aside the sludge accumulated in the concentration chamber, promoting concentration. The sludge scraped up by the bridge member is rolled and discharged in a ridge-like shape from the outlet, increasing the surface area of ​​the accumulated sludge and making it easier for the liquid inside to drain. In addition, the sliding member that slides against the inner surface of the external cylindrical screen regenerates the screen, enhancing the discharge effect of the filtering surface. [Brief explanation of the drawings]

[0017] [Figure 1] 1 is a longitudinal sectional view of a drum-type concentrator according to the present invention. [Figure 2] 1B is a side view and a front view of the sliding contact rake. [Figure 3] FIG. 10 is a front view of the sliding rake of the first embodiment. [Figure 4] 10A and 10B are a side view and a front view of a sliding contact rake according to another embodiment 2 of the present invention. [Figure 5]11A and 11B are a side view and a front view of a sliding contact rake according to another embodiment 3 of the present invention. [Figure 6] 10A and 10B are a side view and a front view of a sliding contact rake according to another fourth embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0018] FIG. 1 is a longitudinal cross-sectional view of a drum-type thickener. Drum-type thickener 1 has a screw shaft 4 with screw blades 3 wound around it, disposed inside a thin, perforated external cylindrical screen 2. An inlet flange 5 and an outlet flange 6 are fitted to the ends of the external cylindrical screen 2, forming a concentration chamber 7 between the external cylindrical screen 2 and the screw shaft 4. The screw shaft 4 is journaled by the inlet flange 5 of the external cylindrical screen 2, which in turn is pivotally supported on a sludge supply pipe 9 supported on a front frame 8. The sludge supply pipe 9 communicates with a sludge supply passage 10 provided on the screw shaft 4, and multiple supply ports 10a, ... provided around the periphery of the screw shaft 4 open into the concentration chamber 7. Flocculated and refined sludge is supplied from a flocculation device to the start end of the concentration chamber 7 formed between the external cylindrical screen 2 and the screw shaft 4.

[0019] The outlet outer cylinder flange 6 is provided with a plurality of discharge ports 11, ... in the circumferential direction, through which the thickened sludge thickened in the thickening chamber 7 overflows. An outer cylinder drive shaft 12 connected to the outlet outer cylinder flange 6 of the outer cylinder screen 2 is journaled in a bearing 14 supported on a rear frame 13, and a screw drive shaft 15 connected to the rear end of the screw shaft 4 is inserted through the outer cylinder drive shaft 12 and journaled in a bearing 17 on a stand 16 provided on the rear frame 13. Sprockets 18, 19 are fitted to the outer cylinder drive shaft 12 of the outer cylinder screen 2 and the screw drive shaft 15 of the screw shaft 4, and a driver (not shown) rotates them in opposite directions at differential speeds.

[0020] The outer cylindrical screen 2 and the screw shaft 4 may be rotated in the same direction at different speeds, but if the outer cylindrical screen 2 and the screw shaft 4 are rotated in opposite directions, the rotation speed of the screw blades 3 will be relatively increased, increasing the number of times the inner surface of the outer cylindrical screen 2 slides in contact with the screen. This will regenerate the filtering surface that would otherwise become clogged with the peripheral end surfaces of the screw blades 3, promoting the discharge of filtrate and enabling the treatment of large amounts of low-concentration sludge.

[0021] The outer cylindrical screen 2 may be rotated at a differential speed for cleaning only when the filtering surface becomes clogged due to the target raw liquid. 2 A filtrate receiving tank is disposed below the outer cylindrical screen 2, and reference numeral 21 denotes a cleaning pipe disposed along the outer cylindrical screen 2, which is used to remove clogging from the filtering surface while rotating the outer cylindrical screen 2.

[0022] A sliding rake 22 is provided on the outer periphery of the screw blade 3. The sliding rake 22 is made up of a bridge member 23 fixed along the axial direction so as to span one pitch of the screw blade 3 between the front and rear screw blades 3, and a bridge member 24 that slides against the inner surface of the outer cylindrical screen 2. 23 The sliding rake 22 rotates in synchronization with the rotation of the screw blades 3 while sliding against the inner surface of the outer cylindrical screen 2, and sequentially discharges the sludge that it has swept aside from the openings (outlet ports 31) formed at predetermined intervals in the sliding member 24.

[0023] FIG. 2 is a side view and a front view of the sliding rake. In this embodiment, flat plates are used for the bridging members 23 of the sliding rake 22, and they bridge the front and back of the screw blades 3 so that they are perpendicular to the inner surface of the external cylindrical screen 2. Both ends of the bridging member 23 are formed with mounting portions 25 so that they can be easily attached and detached from the screw blades 3, and are fixed to the screw blades 3 by known methods such as bolts and nuts. One side closest to the external cylindrical screen 2 is formed with an uneven shape to leave a predetermined gap. The pitch of the projections 26 and recesses 27 is determined appropriately depending on the spacing between the screw blades 3 and the properties of the sludge. A sliding contact member 24 is fixed to the protrusion 26 so as to be in sliding contact with the inner surface of the outer cylindrical screen 2 during operation. The sliding contact member 24 is made of an elastic material such as resin or rubber so as not to damage the outer cylindrical screen 2. The sliding contact member 24 may be configured to be detachable using bolts, nuts, etc.

[0024] The sliding contact side of the sliding rake 22 is formed in an uneven shape, allowing some sludge to pass through the outlet 31 (recess 27). As the screw blades 3 rotate, the sliding contact rake 22 rotates, sweeping aside the sludge remaining in the concentration chamber 7. At that time, the sludge scraped up along with the protrusions 26 rolls and is discharged from the outlet 31, where it is deposited in ridges on the inner surface of the outer cylindrical screen 2. The rolling action and the increased surface area caused by the sludge being deposited in ridges promote the discharge of liquid from the sludge. The liquid discharged from the sludge passes through the filtering surface of the outer cylindrical screen 2, which has been regenerated by the sliding member 24, and is discharged to the outside. The deposited sludge is scraped aside by the protrusions 26 before being scraped up to the top of the outer cylindrical screen 2, and is then discharged sequentially from the outlet 31, so there is no breakdown of thickened flocs due to falling.

[0025] The sludge that has been pushed aside by the sliding rake 22 and deposited in ridges is transported to the discharge side by the screw blade 3. When each deposited ridge is pressed by the screw blade 3, it rolls on the surface of the screw blade, further promoting the thickening action.

[0026] FIG. 3 is a front view of the sliding rake of the first alternative embodiment. In (a), the side of the bridge member 23 remote from the outer cylindrical screen 2 is formed unevenly to leave a predetermined gap. As the screw blades 3 rotate, the sliding rake 22 rotates, scraping away sludge remaining in the concentration chamber 7. During this process, sludge accumulates on the surface of the sliding rake 22, but if the accumulated amount exceeds the limit, it is discharged onto the backside of the sliding rake 22 through an outlet 31 formed on the remote side and accumulates in the form of ridges on the inner surface of the outer cylindrical screen 2. As part of the sludge accumulated on the surface rolls toward the outlet 31, it promotes the discharge of water from the sludge to the outside.

[0027] A sliding contact member 24 is fixed to the edge of the bridging member 23 near the outer cylindrical screen 2, which regenerates the filtering surface of the outer cylindrical screen 2 over its entire length, thereby promoting the thickening of the sludge discharged from the outlet 31.

[0028] In (b), a plurality of openings are formed at predetermined intervals in the axial direction of the screw shaft 4 at predetermined positions of the bridging member 23. As in (a), sludge accumulates on the surface as the sliding rake 22 rotates, and excess sludge is discharged to the back side of the sliding rake 22 through an outlet 31 that connects the front and back, and accumulates in the form of ridges on the inner surface of the outer cylindrical screen 2. Also, as in (a), the sliding member 24 is fixed over its entire length.

[0029] In addition, the edge of the bridging member 23 adjacent to the outer cylindrical screen 2 may be bent in the rotation direction so that the sludge scraped by the sliding contact rake 22 can be discharged smoothly from the outlet 31.

[0030] FIG. 4 is a side view and a front view of a sliding rake according to another embodiment 2. As shown in (a), in order to make it easier for the sludge scraped up during rotation to flow into the outlet 31 and to reduce resistance when scraping through the sludge, the convex portion 26 of the flat plate may be twisted left and right to make it easier for the sludge to flow into the adjacent concave portion 27.

[0031] As shown in (b), a guide member 28 may be provided on the rotation direction surface (raising surface) of the convex portion 26 to facilitate the flow of the raked sludge into the outlet 31. To apply this to the embodiment of Figure 3, a slope may be provided to guide the sludge from the adjacent side of the outer cylindrical screen 2 to the outlet 31.

[0032] Furthermore, as shown in (c), the flat plate may be twisted to form a spiral. In this case, the screen is regenerated while the spiral blade sweeps through the sludge, and the sludge passes through the gaps between the pitches of the spiral blade and is deposited in ridges.

[0033] FIG. 5 is a side view and a front view of a sliding contact rake according to another embodiment 3. In other Example 2, comb-shaped irregularities are provided on the bridging member 23, thereby forming recesses 27 (outlet 31) between adjacent protrusions 26, whereas in Example 3, no recesses 27 are provided and adjacent protrusions 26, 26 are processed differently, resulting in the formation of an outlet 31, which is different from Example 2.

[0034] 1(a) shows a structure in which a plurality of protrusions 26 are formed by cutting the bridging member 23, and the odd-numbered or even-numbered protrusions 26 are twisted left and right. As the bridging member 23 rotates, before the accumulated sludge is scraped up to the top of the outer cylindrical screen 2, the sludge is discharged from the outlets 31 formed by the twisted protrusions 26 and deposited in ridges on the inner surface of the outer cylindrical screen 2.

[0035] If necessary, all of the convex portions 26 may be twisted. Also, the twist angle of the odd-numbered or even-numbered convex portions 26 can be adjusted appropriately so that the optimum ridges can be generated by the swept-apart sludge.

[0036] 1(b) shows a structure in which a plurality of protrusions 26 are formed by cutting the bridging member 23, with the odd-numbered and even-numbered protrusions 26 inclined in the direction of rotation and the direction opposite to the direction of rotation, respectively. Before the accumulated sludge is scraped up to the top of the outer cylindrical screen 2 by the rotation of the bridging member 23, the sludge is discharged from outlets 31 formed by the inclination of adjacent protrusions 26 and is deposited in ridges on the inner surface of the outer cylindrical screen 2.

[0037] In this embodiment, all the convex portions 26 are inclined, but only the odd-numbered or even-numbered convex portions 26 may be inclined as required.

[0038] As in the other embodiment 2, a sliding member 24 is fixed to the edge of the bridging member 23 near the outer cylindrical screen 2, and the filtering surface of the outer cylindrical screen 2 is regenerated over the entire length, thereby promoting the thickening action of the sludge discharged from the outlet 31.

[0039] FIG. 6 is a side view and a front view of a sliding rake according to another embodiment 4. The bridge member 23 of the sliding rake 22 is made up of a plurality of members. In this embodiment, the bridge member 23 is made up of a rod portion 29 and a plate portion 30. The rod portion 29 bridges the front and back of the screw blade 3, and a plurality of plate portions 30 are suspended from the rod portion 29. The plate portions 30 have a predetermined gap between them and are formed in an uneven shape. Both ends of the rod portion 29 are fixed to the screw blade by a known method. 3 The end of the plate portion 30 is close to the outer cylindrical screen 2, and a sliding contact member 24 is fixed to the end of the plate portion 30 so as to be in sliding contact with the inner surface of the outer cylindrical screen 2.

[0040] For a bridging member 23 made up of multiple members, the plate portion 30 may be inclined as shown in Figures 3(a) to (c), a guide member 28 may be provided on the plate portion 30, or the plate portion 30 may be spirally wound around the rod portion 29.

[0041] The sliding rakes 22 are appropriately installed from the supply section to the discharge section of the concentration chamber 7. The height and shape of the sliding rakes 22 and the pitch of the convex sections 26 and concave sections 27 are appropriately designed according to the concentration level of the raw liquid and the specifications of the drum-type concentrator 1. Furthermore, multiple sliding rakes 22 may be arranged side by side at the same pitch. [Industrial Applicability]

[0042] The drum-type concentrator of the present invention can promote the thickening process by plowing the sludge accumulated at the bottom into ridges while regenerating the filtering surface of the external cylindrical screen. This stabilizes the transfer equipment and transfer method to downstream equipment, as well as downstream processes such as dehydration, digestion, and drying, improving overall manageability. [Explanation of symbols]

[0043] 1. Drum type thickener 2 Outer cylinder screen 3 screw blades 4 screw shaft 7 Concentration chamber 11 Outlet 22 Sliding rake 23 Bridge members 24 Sliding contact member 26 Convex part 31 Outlet

Claims

1. A thickener in which a concentration chamber (7) is formed by a screw shaft (4) around which an external cylindrical screen (2) and a screw blade (3) are wound, sludge in the concentration chamber (7) is transported by the screw blade (3) while filtrate is separated from the external cylindrical screen (2), and the thickened sludge is discharged from a discharge port (11) of the concentration chamber (7), Bridge members (23) fixed to the front and back of the screw blades (3) along the axial direction of the screw shaft (4); a sliding contact member (24) fixed to a side of the bridging member (23) adjacent to the outer cylindrical screen (2) and in sliding contact with the inner surface of the outer cylindrical screen (2); an outlet (31) formed by a recess in a bridge member (23) formed unevenly so that a predetermined gap is formed between the edge close to the outer cylindrical screen (2) or the edge far from the outer cylindrical screen (2), and through which a portion of the sludge is discharged in a ridge-like shape; A sliding rake (22) comprising A drum-type concentrator characterized by:

2. A concentrator in which a concentration chamber (7) is formed by a screw shaft (4) around which an external cylindrical screen (2) and a screw blade (3) are wound, sludge in the concentration chamber (7) is transported by the screw blade (3) while filtrate is separated from the external cylindrical screen (2), and concentrated sludge is discharged from the discharge port (11) of the concentration chamber (7), Bridge members (23) fixed to the front and back of the screw blades (3) along the axial direction of the screw shaft (4); a sliding contact member (24) fixed to a side of the bridging member (23) adjacent to the outer cylindrical screen (2) and in sliding contact with the inner surface of the outer cylindrical screen (2); an outlet (31) formed between the pitches of the spiral blades of the spirally formed bridging member (23), through which a portion of the sludge is discharged in a ridge-like shape; A sliding rake (22) comprising A drum-type concentrator characterized by:

3. A concentrator in which a concentration chamber (7) is formed by a screw shaft (4) around which an outer cylindrical screen (2) and a screw blade (3) are wound, sludge in the concentration chamber (7) is transported by the screw blade (3) while filtrate is separated from the outer cylindrical screen (2), and concentrated sludge is discharged from the discharge port (11) of the concentration chamber (7), Bridge members (23) fixed to the front and back of the screw blades (3) along the axial direction of the screw shaft (4); a sliding contact member (24) fixed to a side of the bridging member (23) adjacent to the outer cylindrical screen (2) and in sliding contact with the inner surface of the outer cylindrical screen (2); an outlet (31) formed between adjacent convex portions (26, 26) by twisting or tilting predetermined convex portions (26) of a bridging member (23) having a plurality of convex portions (26), and through which a portion of the sludge is discharged in a ridge-like shape; A sliding rake (22) comprising A drum-type concentrator characterized by:

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