Liquid purification or separation – Filter – Supported – shaped or superimposed formed mediums
Reexamination Certificate
2000-05-22
2001-12-25
Walsh, Donald P. (Department: 3653)
Liquid purification or separation
Filter
Supported, shaped or superimposed formed mediums
C209S303000, C210S784000, C210S174000, C241S280000, C241SDIG014
Reexamination Certificate
active
06332984
ABSTRACT:
BACKGROUND OF THE INVENTION
PRIOR ART
This invention relates to the combination of a solid waste comminuting apparatus and a screening system to divert solid matter contained in an influent stream to the comminutor for purposes of size reduction. Prior screening/comminuting systems are disclosed in U.S. Pat. No. 5,505,388, incorporated here by reference. As set forth in the '388 patent, as is well known in waste water treatment, there are many environments where large volumes of liquid require initial processing for purposes of coarse screening so that large solid objects are diverted in the influent stream and their size reduced by a grinding unit. The material, now of a reduced size, is either removed at the point of reduction or re-introduced into the stream for further processing downstream.
This invention is an improvement over the technology disclosed in U.S. Pat. No. 5,505,388. The '388 patent and the commercial technology stemming from it represented a significant improvement over prior vertically oriented bar screens which were typically used in waste water treatment plants for the purposes of removing solids from a liquid flow. Those prior devices thus utilized rakes, or the like which moved at an angle generally vertical, and therefore perpendicular to the fluid flow in a vertical plane. This resulted in undesirable hydrostatic effects in addition to a propensity of such systems to clog, when fine screens are used, and require a considerable amount of power for purposes of lifting solid materials.
The '388 technology departed from this prior technique by integrating into a common housing a diverter unit, for example a rotating drum placed directly in the fluid flow with an adjacent comminutor disposed in that flow to receive solids that were diverted by the drum. The drum and the comminutor were commonly powered. Consequently, the drum allowed fluid to pass through it but at the same time presented a barrier for solid matter that could not pass through the screening elements. The solid matter was then diverted to one side of the fluid flow where it was then ground into smaller particles and then those particles remain in the stream for substantive downstream processing.
A variant of this basic technique of diverting solids in the stream used double drums, one placed on each side of the comminutor. This system is particularly effective for wide flow channels. By this technique, flow rates are maintained in the stream but, solids are efficiently diverted toward the comminutor for size reduction.
These systems have been commercially successful and as a result of that success a number of areas of further improvement have been identified. One area of improvement is in the drive system for the comminutor and the drum. For example it is desirable to incorporate the capability to tighten the stack of the comminutor from the top as disclosed in U.S. Pat. No. 5,478,020. However since the screen assembly and the drive train are located in the top end housing of integrated systems, top stack tightening was not considered to be feasible. Additionally in prior systems rags could wrap around the lowest cutters and combined with grit would degrade the casting material of the end housing. The result was an expensive repair for the entire end housing.
Another area of improvement deals with the diverter and the manner of support. The diverter, typically a drum, employed a side rail on one side to improve flow characteristics and provide structural support. To maintain overall rigidity of the system additional components were required. This was a face plate attached to top and bottom end housings to complete the frame with the side rail. As a part of the frame prior designs used a face plate bolted to the front of the device which served as structure extending the width of the unit. This framing served to mount the overall frame in a sewage channel when it was lowered and secured to a fixed metal structure fastened to opposing walls of the channel. As can be appreciated the face plate is a fixed dimension and mounting was thus a function of channel width and the need to size the framework to match.
Prior designs used a drum having a center shaft running vertically the length of the drum. Small particles of rags and other solids in the waste stream entering the interior of the drum through screen apertures could wrap on the center shaft. Eventually this buildup on the shaft would increase, enlarging in diameter and caused an internal blockage. In turn a loss of flow through the screen could result decreasing the efficiency of the screen.
Previous drum configurations used intermediate sprockets to support the drum in a spatial arrangement along the central shaft of the drum. Any portion of the screen between the sprockets was unsupported except by the interconnection of the screen material itself. This lack of support caused an hour glass effect between the interface of the screen and the grinder. That is the outer surface of the screen parallel to the axis of rotation would not be in alignment causing gaps at the interface with the grinder.
Prior screening systems, for example those described in U.S. Pat. No. 4,919,346 used an internal deflector. This was possible since the diverter was a screen, elongated with two interior shafts. However, in the context of a rotating drum of the type in the '388 patent such internal deflectors could not be incorporated because the diverter was configured around sprockets containing spokes.
SUMMARY OF THE INVENTION
Given the desire to improve the state of the art in the screening and size reduction of solids in a fluid stream it is an object of this invention to provide an integrated diverter and grinder unit that has improved construction yet is easily maintained.
It is yet another object of this invention to provide an intergrated diverter and grinder unit which has improved flow characteristics using an internal deflector and side rails.
A further object of this invention is to provide a combined diverter and grinder unit which has an improved screen configuration that improves flow yet efficiently diverts solids to the grinder.
These and other objects of this invention are accomplished by means of an integrated system which utilizes a common mounting structure for both the diverter and the grinding unit including an integral vertical guide rail to facilitate mounting in the waste water channel.
A wear plate is provided for the bottom end housing that bolts on and protects the main end housing casting.
Preferably the diverter is in the form of a cylinder that is shaftless within the cavity of the drum. Vertical ribs of the drum which attach top intermediate and bottom sprockets extend inwardly towards the interior of the drum. The ribs form and assist in the removal of solids from the face of the drum.
In one preferred embodiment of the drum a continuous coil is used in an helical or “slinky” type of configuration. This type of drum, also a centerless shaft configuration, permits a higher percentage of open area to enhance flow capabilities through the device.
The drum is positioned so that its outer circumferential surface is substantially tangential to a circle drawn to circumscribe the elements of an adjacent cutter blade assembly. The screen may be placed at either the right or the left of the grinder unit. Alternatively, a pair of diverters can be employed with the grinder unit positioned in the center, with both diverters driven by a common drive source off the grinding unit. The drive system utilizes stub shafts at top and bottom to facilitate removal of the drum without disassembly of the unit.
This invention will be described in greater detail by referring to the drawings and the description of the preferred embodiments which follows.
REFERENCES:
patent: 2106851 (1938-02-01), Nordell
patent: 2163977 (1939-07-01), Ferry
patent: 2199729 (1940-05-01), Peterson
patent: 2342927 (1944-02-01), Durdin, Jr
patent: 2614695 (1952-10-01), Nordell
patent: 2672985 (1954-03-01), Nordell
patent: 2933189 (1960-04-01), Jellesma
patent:
Boyd Ramon E.
Chacon Armando I.
Duecker Ronald A.
Fennessy Craig J.
Freeman, Jr. Winslow P.
Beauchaine Mark J.
Chambers, Boyd and Associates
Sughrue & Mion, PLLC
Walsh Donald P.
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