Imperforate bowl: centrifugal separators – Rotatable bowl – Including driven material-moving means therein
Patent
1991-02-05
1993-03-30
Coe, Philip R.
Imperforate bowl: centrifugal separators
Rotatable bowl
Including driven material-moving means therein
494 84, B04B 120, B04B 304, B04B 908
Patent
active
051979390
DESCRIPTION:
BRIEF SUMMARY
This invention relates to a decanter centrifuge comprising a rotatably journalled bowl and a rotatable screw conveyor journalled in the bowl and of the type in which the conveyor is connected with the bowl through a reduction gear provided with a housing co-rotating with the bowl, a driven shaft connected with the conveyor, and a drive shaft whose number of revolutions determines the relative number of revolutions of the conveyor relative to the bowl.
WO87/06856 describes a decanter centrifuge in which the housing of the reduction gear is co-rotating with the bowl and from FR-A 2,070,485 it is known to attach the housing of the reduction gear fixedly to a flange at one end of the bowl.
From U.S. Pat. No. 3,685,722 it is known to connect the shafts between the co-rotating gear and the conveyor and/or the bowl of a decanter centrifuge through torsionally flexible couplings in order to prevent strain on the gear-wheels of the reduction gear due to so called "chatter" or frequent large fluctuations in torque on the conveyor.
Such decanter centrifuges are used for separating a liquid/solids mixture supplied to the interior of the bowl into a solids phase and one or more liquid phases. This is obtained by rotating the entire bowl at a high number of revolutions and driving at the same time the conveyor at a compartively low number of revolutions relative to the bowl, that is effected by means of the reduction gear which may either be mechanical or hydraulic. Due to the high number of revolutions of the bowl it is in all general applications only possible to transfer the necessary torque between conveyor and bowl by means of such a co-rotating gear.
The separating effect of the centrifuge and its capacity depend on the number of revolutions and the inner diameter of the bowl and on the length of the separating space in such a manner that an increase of each of said parameters, other things being equal, will cause an increase of the separating effect and/or the capacity.
The separating effect and the capacity of the centrifuge are, however, restricted by the critical number of revolutions of the rotating system and is further limited in practice in that an allowable maximum number of revolutions which is somewhat lower than the critical number of revolutions is stipulated considering the stresses occurring in the rotating parts and the working conditions of the centrifuge, such as expected wear, vibration of the decanter as a whole, and so on.
The critical number of revolutions depends, inter alia, on the mass of the rotating parts and, by reducing said mass, the critical number of revolutions may be increased. In view of the fact that the above mentioned co-rotating gear constitutes a substantial portion of the total rotating mass in a decanter centrifuge, it may be desirable to separate the gear from the bowl in order to increase the critical number of revolutions of the decanter centrifuge.
The decanter centrifuge according to the invention is characterized in that the reduction gear is rotatably journalled in separate bearings, in that its housing is connected with the bowl through a flexural but torsionally stiff coupling, and in that the driven shaft of the reduction gear and the conveyor are likewise connected through a flexural but torsionally stiff coupling.
By supporting the gear in separate bearings and eliminating the possibility of transferring bending moments from the gear to the bowl and the conveyor there is obtained a structure in which the gear, from a dynamic point of view is largely completely insulated from the latter components and thus does not exert any influence on the critical number of revolutions of the decanter centrifuge. This produces the advantage over the prior art centrifuges of the above-mentioned type that the allowable maximum number of revolutions of the centrifuge according to the invention may be increased or, for example, that the length of the separating space may be increased without increasing the critical number of revolutions. In both cases the result is an increase of
REFERENCES:
patent: 1188113 (1916-06-01), Thomas
patent: 2614748 (1952-10-01), Ritsch
patent: 2715822 (1955-08-01), Anderson
patent: 3097167 (1963-07-01), Beyerle
patent: 3187997 (1965-06-01), Gooch
patent: 3428246 (1969-02-01), Finkelston
patent: 3685722 (1972-08-01), Nichols
patent: 3779451 (1973-12-01), Lehman
patent: 3938354 (1976-02-01), Lehman
patent: 4069967 (1978-01-01), Crosby et al.
patent: 4141488 (1979-02-01), Gense
patent: 4186096 (1980-01-01), Areaux
patent: 4190194 (1980-02-01), Amero
patent: 4303192 (1981-12-01), Katsume
patent: 4327862 (1982-05-01), Jakobs
patent: 4339072 (1982-07-01), Hiller
patent: 4362521 (1982-12-01), Puck
patent: 4385897 (1983-05-01), Mallet
patent: 4391594 (1983-07-01), Hannibal
patent: 4513566 (1985-04-01), Rajsigl
patent: 4540385 (1985-09-01), Krude
patent: 4861313 (1989-08-01), Zeiser
Cederkvist Jan
Goddik Bjarne
Alfa-Laval Separation A/S
Coe Philip R.
Till Terrence R.
LandOfFree
Decanter centrifuge does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Decanter centrifuge, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Decanter centrifuge will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1277868