US 6,746,599 B2 · Staged settling process for removing water and solids from oils and extraction froth

Abstract

Diluent-diluted bitumen froth containing bitumen and naphtha diluent, hydrocarbons, water, sand and fines (collectively “dilfroth”) is fed into a vapor-tight gravity settler (‘splitter’) and temporarily retained to produce a bottom layer of tails comprising sand and middlings, a rag layer of discrete three-dimensional structures, each comprising hydrocarbons contained in a skin of fines, and a top layer of hydrocarbons containing small droplets of water and fines (‘raw dilbit’). The flux in the splitter is less than 6 m3/h of dilfroth fed per m2 of horizontal cross-sectional rag area. The in-coming dilfroth is fed directly into the splitter middlings. Demulsifier is added to the overflow stream of raw dilbit and the mixture is subjected to prolonged settling in a vapor-tight polisher tank, to produce polished dilbit containing less than 1.0 wt. % water and 0.3 wt. % solids. The splitter underflow tails, containing less than 15 wt. % bitumen, is mixed with additional diluent to raise the diluent/bitumen ratio to 4:1 to 10:1 and is gravity settled in a vapor-tight scrubber. Scrubber overflow, mostly diluent containing residual bitumen stripped from the tails, is recycled to the splitter. In concept, the sand is first separated from the bitumen in the stripper. The substantially sand-free bitumen can then feasibly be treated with chemical demulsifier and subjected to prolonged settling in the polisher to reduce water and fines contents to low levels. Bitumen lost with the splitter tails is recovered in the scrubber using a high concentration of diluent. The scrubber overflow of bitumen and diluent is recycled to the stripper to conserve diluent.

Claims15

Dependent claims

A process for cleaning naphtha-diluted bitumen froth (“dilfroth”) comprising bitumen and naphtha hydrocarbons contaminated with water and solids, the solids comprising sand and fine clay particles (“fines”), comprising:

providing a splitter vessel forming a vapor-tight chamber for gravity settling, said vessel having an overflow outlet at its upper end, an underflow outlet at its lower end and means for feeding incoming dilfroth into the chamber;
feeding dilfroth into the chamber through the feed means and temporarily retaining it therein so that the dilfroth separates to form a bottom layer of tails comprising aqueous middlings and sand, said tails containing some hydrocarbons, an intermediate layer of rag comprising water, fines and hydrocarbons collected in discrete three dimensional structures, said rag layer having a horizontal cross-sectional area, and a top layer of raw dilbit comprising hydrocarbons containing some water and fines, said middlings combining with the rag and dilbit to create a discernible hydrocarbons/water interface;
the feed means being operative to directly feed the incoming dilfroth into the middlings;
removing dilbit through the overflow outlet;
and
removing tails through the underflow outlet, said tails containing less than 20 wt. % of the hydrocarbons in the froth.

3 more elements

Dependencies are inferred from the claim text.

Staged settling process for removing water and solids from oils and extraction froth

Life of this patent

Staged settling process for removing water and solids from oils and extraction froth

Life of this patent

Abstract

Claims15