VERTICAL SCREW SCREEN WITH OPTIMIZED TRANSPORT FEATURES

Abstract

Aspects of the disclosure provide a screw conveyor for discharging solids from a solid/liquid waste stream is provided and comprises a cylindrically shaped screen segment including perforated screen segments and an inlet for receiving a stream including solid and liquid materials, the perforated portions configured to permit liquids and smaller materials to pass therethrough. The conveyor includes a rotor auger disposed within the screen segment and includes helical flights configured to move solid materials larger than perforations on the perforated screen to move vertically when rotated. A drive motor is included to rotate the rotor auger and anti-rotation elements are disposed radially outward between adjacent perforated screen segments and configured to prevent rotation of solid materials to permit the rotor auger to move the solid materials in an axial direction of the rotor auger rotation.

Claims

1. A screw conveyor for discharging solids from a solid/liquid waste stream comprising: a cylindrically shaped screen segment including perforated screen segments and an inlet for receiving a stream including solid and liquid materials, the perforated portions configured to permit liquids and smaller materials to pass therethrough; a rotor auger disposed within the screen segment including helical flights configured to move solid materials larger than perforations on the perforated screen to move vertically when rotated; a drive motor to rotate the rotor auger; anti-rotation elements disposed radially outward between adjacent perforated screen segments configured to prevent rotation of solid materials to permit the rotor auger to move the solid materials in an axial direction of the rotor auger rotation.

2. The screw conveyor according to claim 1, wherein the anti-rotation elements are U-shaped channels open toward the rotor auger.

3. The screw conveyor according to claim 1, wherein innermost portions of the anti-rotation elements in the radial direction do not extend inward of the perforated screen segments.

4. The screw conveyor according to claim 1, further comprising a rotor shoe at a lowermost portion of the helical flights and at and end of the helical flights of the rotor auger that extends axially upward from the helical flights.

5. The screw conveyor according to claim 4, wherein the rotor shoe has a triangular cross section to taper at a thinnest portion on an edge opposite to where the rotor shoe is attached to the helical flights.

6. The screw conveyor according to claim 4, wherein the rotor shoe is adjustably attached to the end of the helical flights.

7. The screw conveyor according to claim 5, wherein a side of the rotor shoe attached to the end of the helical flights protrudes above an upper surface of the helical flights.

8. The screw conveyor according to claim 1, further comprising a center pipe that extends axially through the center of the rotor auger and forms an open portion within a lower most end of the center pipe; a bottom plate attached to the bottom of the cylindrical shaped screen segment; and a bushing configured to fit within the center pipe that is attached to the bottom plate.

9. The screw conveyor according to claim 1, wherein an axis of rotation of the rotor auger is inclined with respect to a gravity direction.

10. The screw conveyor according to claim 1, wherein an axis of rotation of the rotor auger extends vertically with respect to a gravity direction.

11. A screw conveyor system according to claim 1, further comprising a transport segment for receiving solid materials from the screen segment and extending vertically upward from the screen segment.

Description

BRIEF DESCRIPTIONS OF THE DRAWINGS

[0021] FIG. 1 is a perspective view illustrating a screw conveyor system in accord with the present disclosure and installed in a wastewater wet well;

[0022] FIG. 2 is a perspective view illustrating various structures of a lower portion of the screw conveyor system;

[0023] FIG. 3 is a perspective view of a perforated screen including structural elements;

[0024] FIG. 4 is a perspective view of a perforated screen segment with the perforated screen removed to show internal features;

[0025] FIG. 5 is a perspective view of a perforated screen including anti-rotation channels;

[0026] FIG. 6 is a perspective view of a perforated screen including anti-rotation channels with the perforated screen removed to show internal features including a rotor shoe;

[0027] FIG. 7 is another perspective view of the perforated screen segment;

[0028] FIG. 8 is a cross-sectional view of a perforated screen taken along an axial centerline to show a center pipe and bushing features;

[0029] FIG. 9 is a perspective lower view of a perforated screen including anti-rotation channels with the perforated screen removed to show internal features including a rotor shoe;

[0030] FIG. 10 is a perspective lower view of a perforated screen including anti-rotation channels with the perforated screen removed to show internal features including a rotor shoe;

[0031] FIGS. 11-13 show variations of a perforated screen that is included and which includes anti-rotation bars.

DETAILED DESCRIPTION

[0032] In one embodiment of the disclosure as shown in FIG. 1, a vertically oriented screw conveyor is mounted in a supporting frame 60, which is in turn fastened to the inner wall of a wet well over a wet well inlet pipe 80 (see FIG. 2). A level probe 70 is mounted either above or on the side of the supporting frame 60. The screw conveyor consists of a screen segment 50, a transport segment 40, discharge segment 20 and drive segment 10. The screen segment is connected to the supporting frame 60 by an installation baffle 90 (see FIG. 2). The screen segment 50 may sit a-top a pedestal support 100 (see FIG. 2). Additional supports may be used to connect the transport segment 40 of the screw conveyor to some portion of the wet well (FIG. 1). A discharge chute 30 is attached to the outlet of the discharge segment 20 and may be supported by chute supports. The drive segment 10, including a speed reducer, drive motor, and shaft seal, is connected to the top end of the rotor contained within the casings of the discharge, transport and screen segments. As shown in FIGS. 3-5, the screen segment 50 may include rolled, perforated, sheet metal screen 110 (FIG. 3), an upper connecting flange 150, a bottom plate 130, an inlet pipe 120, horizontal & vertical stiffeners 140 and a spray water manifold.

[0033] The rotor extending from the screen segment 50 through the discharge segment 20 may include: spiral, or sectional flighting 180, a center pipe 170 or torque tube, a drive shaft and, one or more discharge paddles. The rotor is driven by the drive segment 10 and may include a coil-wound, or sectional disk brush 160 that is affixed to the top, bottom or outer circumferential surface of the spiral in the area of the perforated screen 110 (FIG. 4) and contacts the inner surface of the screen 110. The spiral or sectional flighting functions to move solids upward through the perforated screen segment 50 to the transport segment 40, and eventually upward to the discharge chute 30.

[0034] To prevent solid materials such as rags from merely rotating with the rotor auger 210, the perforated screen 110 includes one or more U-shaped, material anti-rotation channels 200 (FIG. 4, 5, 6, 7) that are oriented axially to the centerline of the screen segment 50 and welded in between adjacent sections of rolled perforated screen section forming the perforated screen segment 50. The web of each anti-rotation channel protrudes radially outward from the perforated screen to form channels “in counter relief” to the inner surface of the perforated screen segment 50.

[0035] A lifting scraper, or rotor shoe 260 may be fastened to the leading-edge, relative to the forward direction of travel, of the tail end of the rotor spiral 280 of the auger rotor 210, (FIG. 6, 9, 10). The lifting scraper may have a triangular cross section and include an adjustment feature allowing the leading edge of the scraper to contact the top surface of the bottom plate 130 of the screen segment 50. A stop feature 270 on the lifting scraper may protrude above the top surface of the rotor spiral 280 of the rotor auger 210 (FIG. 10).

[0036] The screw conveyor may also include a rotor centering bushing feature 230, 240 (FIG. 8) and which may consist of: (i) a rotor centering bushing 240; (ii) a rotor centering bushing socket 230, and; (iii) centering bushing fastening hardware 250. The centering bushing socket 230 is fitted in the tail end of the rotor center pipe 170 that traverses the rotor down the center of the spiral (FIG. 7, 8). The centering bushing hardware 250 fastens the centering bushing 240 to the rotor side of the bottom plate 130 through a hole in the center of the plate. The centering bushing 240 protrudes into a pocket in the centering bushing socket 230 with reasonable minimum clearance between the outer cylindrical surface of the centering bushing 240 and the inner cylindrical surface of the centering bushing socket 230.

[0037] In another embodiment of the disclosure, the material anti-rotation channels may be included in the perforated screen trough of an inclined, screening screw conveyor (FIG. 11, 12, 13.)