Imperforate bowl: centrifugal separators – Process
Patent
1991-05-08
1998-02-24
Till, Terrence
Imperforate bowl: centrifugal separators
Process
494 70, 494 71, B04B 108
Patent
active
057207054
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a method of freeing a liquid from a substance dispersed therein and having a larger density than the liquid, and a plant for performing said method. A plant of the kind to which the invention is related includes, apart from a source of liquid of said kind, a centrifugal separator comprising a rotor, which is rotatable in a predetermined direction and defines a separation chamber; a stack of conical separation discs arranged coaxially with the rotor in the separation chamber; spacing means formed and arranged between the separation discs such that they define several flow paths between two adjacent separation discs, each of which flow paths has an inlet part and an outlet part situated at different distances from the rotational axis of the rotor; means for the supply of liquid from said source to the inlet part of each flow Path; and means for removing liquid having been freed from said dispersed substance from the outlet part of each flow path.
Centrifugal separators of this kind have been known for a long time. In these centrifugal separators said flow paths between the separation discs usually are delimited by radially extending spacing means between the separation discs. If inlet channels for a liquid are formed by axially aligned distribution holes in the separation discs, these distribution holes most often are placed between and are equally spaced from the radially extending spacing means. However, proposals have been made to place said holes, instead, close to the spacing means and to give the spacing means an extension other than a pure radial extension. Such proposals have been made for instance in the Swedish patent specification 156,317.
The object of the present invention has been to provide a centrifugal separator of the initially described kind having a better separation efficiency than previously known centrifugal separators intended for the separation of a substance dispersed in a carrying liquid and having a larger density than the latter. The substance in question may be constituted by solids but, alternatively, it can be constituted by particles of a liquid other than the carrying liquid.
This object is achieved according to the invention in a centrifugal separator of this kind in that two adjacent spacing members between two adjacent separation discs are shaded such that they form between themselves a flow path extending from its inlet part to its outlet part in a direction which has one radial component and one component in the circumferential direction of the rotor and turned against or opposite to the predetermined rotational direction of the rotor.
A comparison between a centrifugal separator designed in this manner and a centrifugal separator designed in a conventional manner and having distribution holes of the above described kind placed between and equally spaced from radially extending spacing means between the separation discs, has shown that the separation efficiency could be 20-50% better with the invention than with the previously known centrifugal separator. The reason why the separation efficiency can be improved by means of the invention is assumed to be the following.
In a conventionally designed centrifugal separator, in which the supplied liquid is intended to flow radially inwards along the above described flow paths, a large part of the actual liquid transport between the inlets and outlets of the flow paths takes place in very thin boundary layers, so called Ekman-layers, formed on the surfaces of the separation discs. A free liquid flow of a substantial magnitude, a so called geostrophic flow, will come up between the two boundary layers in each interspace between adjacent separation discs, but this liquid flow is directed substantially in the circumferential direction of the rotor and, also, forms local eddies between the separation discs, particularly close to the above mentioned distribution holes therein.
In the said boundary layers the liquid to a large extent flows radially inwards in the rotor both along the separation disc
REFERENCES:
patent: 355050 (1886-12-01), Backstrom
patent: 432719 (1890-07-01), Bechtolsheim
patent: 902913 (1908-11-01), Risberg
patent: 945903 (1910-01-01), Bailey
patent: 958769 (1910-05-01), Richardson
patent: 1006622 (1911-10-01), Bailey
patent: 1208461 (1916-12-01), Blanc
patent: 1356665 (1920-10-01), Sturgeon
patent: 1718081 (1929-06-01), Ruda
patent: 2081406 (1937-05-01), Mazza
patent: 2331352 (1943-10-01), Sharples
patent: 2578485 (1951-12-01), Nyrop
patent: 2690900 (1954-10-01), Zachariassen
patent: 2748668 (1956-06-01), Hornbostel
patent: 2910226 (1959-10-01), Thylefors
patent: 3376360 (1968-04-01), Feezel
patent: 3606147 (1971-09-01), Broadbent
patent: 3771353 (1973-11-01), Jenkins
patent: 4262841 (1981-04-01), Berber
patent: 4427407 (1984-01-01), Pashedag
Borgstrom Leonard
Carlsson Claes-Goran
Franzen Peter
Inge Claes
Lagerstedt Torgny
ALFA-Laval Separation AB
Till Terrence
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