Capacitance system for heavy phase discharge of second stage centrifugal separation circuit

In a second stage centrifugal;

• separator circuit which separates heavy phase fluid from degritted diluted bitumen froth, the improvement which comprises:
• a plurality of disc nozzle centrifugal separators, each separator having centripetal pump means, including an outlet, for removing heavy phase fluid from said separator, and, in operation, a diluted bitumen-heavy phase fluid interface whose position can be shifted by a change in the fluid pressure at the pump means outlet;
• a capacitance vessel comprising a first section and a second section which is an extension of the first section, said first section having an elongate tubular horizontal form and an internal cross sectional area several multiples of that of a pipe designed to just accommodate the expected maximum flow from the centripetal pump means outlets;
• an upstanding first weir extending across the interior of the capacitance vessel at the junction of the first and second sections, said first weir and first section combining to form a reservoir chamber for containing a reservoir of heavy phase fluid, said first weir being operative to separate diluted bitumen from the heavy phase fluid in the reservoir chamber thereby preventing an accumulation of diluted bitumen in the reservoir chamber;
• means associated with the vessel, for supplying make-up fluid to the reservoir when required;
• conduit means connecting the outlet of each centripetal pump means with the reservoir beneath its surface, whereby the heavy phase fluid from the outlets is distributed along the length of the reservoir;
• means, associated with the capacitance vessel, for pressurizing its contents, to thereby maintain fluid backpressure at the centripetal pump means outlets;
• means forming segregated first and second chambers in the second section, each said chamber having an inlet and outlet;
• second weir means positioned downstream from the first weir and at the inlet to the first chamber, for separating diluted bitumen from any fluid overflowing the first weir, to produce a diluted bitumen-rich fraction which flows into the first chamber;
• third weir means, positioned downstream from the first weir and at the inlet to the second chamber, operative to permit only heavy-phase product to enter said second chamber;
• means for removing diluted bitumen-rich product from the outlet of the first chamber;
• and
• means for removing diluted bitumen-poor product from the outlet of the second chamber.

A method for treating a plurality of heavy phase fluid streams produced by a plurality of disc-nozzle centrifugal separators, each having bowl nozzles and being fed degritted diluted bitumen froth comprising:

• transferring the streams into a reservoir of heavy phase fluid contained in a vessel;
• retaining transferred fluid in the reservoir to enable a portion of the diluted bitumen contained in said fluid to reach the surface of the reservoir;
• separating floating diluted bitumen from the reservoir and recovering it from the vessel as a separate diluted bitumen-rich product;
• recovering transferred fluid from the vessel as a separate diluted bitumen-poor product;
• and
• returning transferred heavy phase fluid from the reservoir to one or more of the separators when said separators require supplemental fluid to satisfy the bow nozzles.