Liquid purification or separation – Processes – Separating
Reexamination Certificate
2000-02-09
2001-02-13
Reifsnyder, David A. (Department: 1723)
Liquid purification or separation
Processes
Separating
C210S788000, C119S224000, C119S232000
Reexamination Certificate
active
06187208
ABSTRACT:
FIELD OF INVENTION
The present invention relates to a debris separating system, more particularly, the present invention relates to a debris separating system suitable for use in removing sediment from aquatic organisms cultivating tanks.
BACKGROUND OF THE INVENTION
It is common practice to grow aquatic organisms such as fish and the like in tanks or bag like structures for the commercial market.
One of the main problems of these systems is the tendency for sediment to build in the bottom of the tank or to be released into the surrounding waters and cause contamination detrimental to the process or the surrounding environment.
There have been numerous proposals and applied systems for cleaning aquaculture tanks. See for example, Canadian patent 1,117,385 issued Feb. 2, 1982 to Casey, Canadian patent 1,292,919 issued Dec. 10, 1991 to Ragnar et al. and Canadian patent applications, 2,000,443 published Apr. 12, 1990 by Arne et al., 2,072,357 published Jun. 20, 1991 by Jorgensen. See also U.S. Pat. Nos. 3,716,025 issued Feb. 13, 1973 to Lawson, 3,870,018 issued Mar. 11, 1975 to Furchtnicht, 4,141,318 issued Feb. 27, 1979 to MacVane, 4,171,681 issued Oct. 23, 1979 to Burger et al., 4,655,169 issued Apr. 7, 1987 to Paliola and U.S. Pat. No. 5,239,839 issued Mar. 15, 1994 to Jorgensen.
Many of the systems described in the patents use circulation of the water in the tank to deliver the sediment to a sediment outlet for example rotating flow in circular tanks to sweep the sediment toward the centre of the tank. U.S. Pat. No. 4,655,169 referred to above describes a system wherein conical grooves are provided in the bottom end of the tank and a circular flow is imparted into the water in the tank to cause the debris that settles to the bottom of the tank to be swept along the conical grooves into a collecting chamber or sump at the center of the tank. This system obviously relies substantially completely on gravity for separation of the sediment from the water i.e. the sediment falls by. gravity to the bottom of the tank and the thus concentrated debris is swept along the helical bottom passages to a sump.
U.S. Pat. No. 5,639,595 issued Jun. 10, 1997 to Lunde et al. employs an annular chamber or sump surrounding a main tank outlet defined by an upper deck spaced from the bottom of the tank to provide a flow inlet extending around the full circumference of the sump. The sump is frusta-conical tapering towards a bottom end that is provided with a debris outlet adjacent to the central or axial main outlet passage from the tank. Outlet holes connect the sump with the main outlet passage at a position well above the debris outlet in the bottom of the sump. Water carrying debris flows into the chamber substantially radial around the full periphery of the chamber and towards the bottom and then flows back up and out through the outlet passages leading to the main passage. Debris falling from the water entering the sump is removed via the debris outlet. This system does not significantly concentrate the sediment for removal.
The centrifugal separation wherein circular flow at high angular velocity of a sediment containing liquid to apply centrifugal force to concentrate the higher density material adjacent to the outer wall of the chamber is well known, for example, in the pulp and paper art, for separation of fiber and shive from water or the mining industry for increasing the concentration of solids carried in the liquid streams.
BRIEF DESCRIPTION OF THE PRESENT INVENTION
It is an object of the present invention to provide an improved sediment separation system particularly suited for use in aquatic organism cultivation tanks or bags.
Broadly, the present invention relates to a method and apparatus for sediment removal from an aquatic tank having water flow patterns therein comprising a sediment removal device at the lower end of said tank, said sediment removal device comprising a substantially circular collecting chamber having an outer wall forming a substantially conical shaped bottom wall about an axis, a funnel shaped upper deck concentric with said axis and having a substantially conical shaped deck portion tapering to a spout portion concentric with and opening through an apex of said substantially conical shaped bottom wall, a waste baffle closing a significant portion of an upper end of said collecting chamber, said waste baffle being axially spaced from said upper deck to define an outlet passage therebetween, said waste baffle extending in from the periphery of said chamber defined by said outer wall toward said spout portion of said funnel shaped upper deck, an outlet opening defined by an outer periphery of said spout portion and an inner end edge of said waste baffle, said outlet connecting said collecting chamber with said outlet passage, an injector defining at least one injector passage extending through said upper deck and said waste baffle and opening into said chamber space outward of said outlet opening and adjacent to the outer periphery of said chamber, said injector passage being shaped to inject liquid from said tank into said chamber and to impart a significant component of velocity of the liquid flowing through said injector passage substantially tangent to said chamber so that said water injected into said chamber flows in a helical path along said substantially conical shaped bottom and passes out through said outlet opening into said outlet passage, and a debris outlet from said chamber at said bottom of said chamber adjacent to said apex.
Preferably, said waste baffle is frusta-conical in shape sloping downward toward said bottom wall from said periphery of said chamber.
Preferably there are a plurality of said injectors symmetrically positioned around said axis.
Preferably the ratio of the open area of said outlet opening to the total cross sectional area of said at least one injection passage is between 0.5 and 1.
The present invention also relates to a method of cleaning debris from the water in a tank comprising providing a collecting chamber at the bottom of said tank, injecting water caring debris from said tank into said collecting chamber adjacent to an outer periphery of said chamber to define vortical flow in said chamber between a conical bottom wall of said chamber and a waste baffle forming a top of said chamber, flowing cleaned fraction of said water from said chamber as a vortex through an outlet opening between said waste baffle and an adjacent portion of a concentric funnel shaped upper deck, passing cleaned water exiting from said outlet opening through an outlet passage formed between said waste baffle and said upper deck as an expanding vortex in said outlet passage and removing a debris rich fraction of said water from said chamber adjacent to said bottom of said chamber.
Preferably said water containing debris is injected into said separation chamber at a tangential velocity to said chamber of at least 0.4 meters/second and more preferably between 0.4 and 1.5 meters/second.
REFERENCES:
patent: 4141318 (1979-02-01), MacVane et al.
patent: 5636595 (1997-06-01), Lunde et al.
Future Sea Technologies Inc.
Reifsnyder David A.
Rowley C. A.
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