Liquid purification or separation – Structural installation – Flume stream type
Patent
1999-03-30
2000-08-01
Lithgow, Thomas M.
Liquid purification or separation
Structural installation
Flume stream type
210159, 210162, 210314, 210415, E02B 508, B01D 2931, B01D 2964, B01D 2994
Patent
active
060962011
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to an apparatus for separation and displacement of bodies, particles and/or similar impurities from a liquid.
BACKGROUND AND PRIOR ART
The term bodies, particles and/or similar impurities is taken in this description to signify all material which, when it is located in a liquid, comes to rest against a separation apparatus, for example a grid or a screen through which the liquid passes. An expression which occurs often for such material is "screenings", consequently, in the continuation of this description, the expression screenings will often be employed for the above-defined matter. The designation "solid substances" also occurs but will be employed in this description generally exclusively for screenings in which the liquid content has been reduced.
In, for example, water treatment plants, in process industries such as pulp factories or paper mills, in food industries, such as slaughter houses, etc., there is a need to be able to remove from liquids bodies and particles and/or similar impurities.
When the screenings have been displaced of out of the liquid, the liquid content of the screenings is high. The total solids is generally less than 5-8%. There is, therefore, a need in the art to be able to reduce the liquid content in the screenings in order to facilitate its continued handling. In total solids contents exceeding 20%, the continued handling of the screenings is substantially facilitated. In cases when the screenings are incinerated, for example in municipal heating plants, even higher total solids contents are naturally extremely desirable, since this entails improved energy yield on combustion.
A further need in the art is that the screenings be freed of soluble, for example biological compounds included in the screenings. This applies particularly to screenings sent to landfill deposition.
From Swedish patent No. 457 637 and German Gebrauchmuster No. G 8905963, there are previously known apparatuses for removing solid bodies and material from a flowing liquid. These documents describe an obliquely upwardly inclined conveyor screw installed in a channel with flowing liquid containing bodies of solid matter. The conveyor screw is disposed in a path which, in its lower region, forms a part-cylindrical screen surface. Above the water surface, the path is designed as a tube or casing surrounding the conveyor screw. In its upper end, the casing is provided with a discharge aperture. In the region ahead of the discharge aperture, the threads of the conveyor screw are of reducing pitch, whereby a certain compression and dewatering take place of the matter being upwardly transported. However, capacity in these apparatuses is extremely low.
Apparatuses of the above described type are employed for mechanical treatment of restricted flows of municipal waste water, treatment plants or for purifying (screening) polluted liquids, for example water within industries such as paper mills, food industries and slaughter houses.
The equipment in existence suffers from a plurality of well known drawbacks and functional problems.
Thus, the upward conveyance of matter which has accumulated on the screening surface is unreliable. When the conveyor screw is designed as a conveyor helix, the screenings are readily washed down through the centre hole of the helix. Another well known drawback in the employment of the conveyor screw with a mechanical centre shaft is that the screenings adhere to the mechanical shaft and to the helical thread and rotate together with these, which greatly obstructs the conveyance function.
It will readily be perceived that, as a result of these inconveniences, the capacity of the equipment is reduced at the same time as such equipment requires manual supervision. In order, to some extent, to improve the conveyance function, it is known in the art to limit the angle of inclination of the conveyor helix. However, this leads to bulky designs and constructions and consequentially increased costs.
A serious drawback in the prior art techn
REFERENCES:
patent: 5034122 (1991-07-01), Wiesemann
patent: 5061380 (1991-10-01), Stevenson
patent: 5078865 (1992-01-01), Huber
patent: 5372713 (1994-12-01), Huber
patent: 5755958 (1998-05-01), Huber
patent: 5840180 (1998-11-01), Filion
English Abstract of SE 457,637 of Jan. 16, 1989.
English Abstract of EP 0640370 Mar. 1, 1995.
English abstract of EP 0565898.
English Abstract of DE 3122131.
Lithgow Thomas M.
Spirac Engineering AB
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