Alfa-Laval Self Cleaning Purifier

Marine Auxiliary Machine

 

A centrifuge bowl capable of being programmed for periodic and regular dumping of the bowl contents to remove the sludge build-up. The sludge discharge takes place through a number of slots in the bowl wall. Between discharges these slots are closed by the sliding bowl bottom, which
constitutes an inner, sliding bottom in the separating space. The sliding bowl bottom is forced upwards against a seal ring by the pressure of the operating liquid contained in the space below it. This exceeds the counteracting downward pressure from the process liquid, because the underside of the sliding bowl bottom has a larger pressure surface (radiusRJ, than its upper side. Operating liquid is supplied on the underside of the bowl via a device known as the paring disc. This maintains a constant operating liquid annulus (radius R3) under the bowl, as its pumping effect neutralizes the static pressure from the supply.


When the sludge is to be discharged, operating liquid is supplied through the outer, wider supply tube so that if flows over the lower edge of the paring chamber (radius R4) and continues through a channel out to the upper side of a sliding ring, the operating slide. Between discharges, the operating slide is pressed upwards by coil springs. It is now forced downwards by the liquid pressure, thereby opening discharge valves from the space below the sliding bowl bottom so that the operating liquid in this space flows out .When the pressure exerted by the operating liquid against the underside of
the sliding bowl bottom diminishes, the latter is forced downwards and opens, so that the sludge is ejected from the bowl through the slots in the bowl wall. Any remaining liquid on the upper side of the operating slide drains through a nozzle . This nozzle is always open but is so small that the outflow is
negligible during the bowl opening sequence.
On completion of sludge discharge, the coil springs again force the operating slide upwards , thus shutting off the discharge valves from the space below the sliding bowl bottom. Operating liquid is supplied through the outer, wider tube, but only enough to flow to the space below the sliding bowl
bottom and force the latter upwards so that the bowl is closed. liquid is supplied, it will flow into the channel to the operating slide and the bowl will open again.
The outer, wider inlet is now closed while the inner, narrower one is open. The paring disc counter-balances the static pressure from the operating liquid supply, and the bowl is ready to receive a further charge of oil. The situation is identical with that shown in the first illustration of the series but
with the difference that the sludge discharge cycle is now accomplished. Periodically the purifier bowl should be stripped and thoroughly cleaned. It is important to remember that this is a precision built piece of equipment, which has been carefully balanced and all parts should be treated with the utmost care.

 

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