Liquid purification or separation – Processes – Separating
Patent
1993-06-08
1995-06-06
Dawson, Robert A.
Liquid purification or separation
Processes
Separating
2105121, 210519, 210521, B01D 2126
Patent
active
054220173
DESCRIPTION:
BRIEF SUMMARY
The invention relates to an apparatus for central charging of circular tanks with sewage water by means of a vertical pipe.
In the field of sewage technology, in known manner circular settling tanks with considerable diameters are used in communal or municipal sewage works for preliminary sedimentation or as final sedimentation tanks for sludge separation following the activation. Common to these circular tanks is that the inflow takes place in the centre of the circular tank via a pipe leading vertically into the tank. The jet is then deflected by constructions of very varied design into the horizontal in order to achieve as uniform as possible a radially symmetrically flowing into the circular tank. However, all these apparatuses have the disadvantage that firstly they are constructionally very complicated and secondly do not permit a controlled guiding of the radial flow in order for example to compensate possible density differences present due to differences of temperature and solid content between the jet and external flow.
The technological background is that the density of the fluid is changed due to sedimentation of the sludge particles in the tank. The charging takes place via a so-called "central structure". After exit of the fluid from the central structure into the outer space the density differences of the suspension compared with the clear water manifest themselves.
In the radial direction, the geometry of the circular tank produces a pronounced retardation of the stream in the flow direction. Since retarded movements generally react very sensitively to disturbances and there is a tendency to detachment, the careful guiding of the radial flow is of great importance. It should be noted here that the solid-charge stream on flowing out into the outer region is deflected downwardly as a whole due to its higher density (Prof. Valentin, Faculty of Hydraulics and Hydrology, Munich Technical University, Dept. 50, 1988 ISSN 0343-1177).
The invention is based on the problem of providing a constructionally simple apparatus for central charging of circular tanks with sewage water in which the deflection of a vertical jet and a uniform radial symmetrical distribution of the flow is to be achieved. The novel apparatus is also to be able to counteract the fact that solid-charged fluid jets are deflected downwardly due to their higher density on flowing out of the apparatus into the circular tank.
This is surprisingly achieved according to the invention by a centrally inserted horizontal circular control disc in the region of the transition from the vertical pipe to a smoothly continuously adjoining trumpet-like widening, the control disc forming an annular gap with the inner periphery of the vertical pipe. By trumpet-like widening it is understood by those of ordinary skill, particularly in view of the drawing figures that the bell shaped body to which is attached the vertical pipe in somewhat similar in appearance and geometry to the bell end of a horn such as for example a trumpet. The surface geometry of this bell shaped or trumpet-like body is such that an angles formed by tangent lines to the inner facing surface of the bell and the horizontal will go successively from about 90 degrees to about 0 degrees. The tangent lines, starting at the transition region and moving toward the detachment edge of the bell, basically go from axially directed to radially directed.
It is not being overlooked that apparatuses and methods are known which impart a different direction to a gas or liquid jet utilizing the so-called Coanda effect. Not however in sewage technology.
As is known, in these central structure the density at the entrance is greater than the density thereafter. However, due to the higher density the flow moves downwardly and swirls the deposited sludge up again. In practice, instead of the required 80% an efficiency of only 60% was achievable. Here, the step according to the invention represents a surprising step forwards.
The advantages achieved with the invention reside in particular therein that t
REFERENCES:
patent: 2098467 (1937-11-01), Sayers et al.
patent: 4224157 (1980-09-01), Join
Felder Anton
Valentin Franz
Dawson Robert A.
Dishong George W.
Felder Anton
Reifsnyder David
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