Patent ID: 8002121

Claim:
An in-line flow separator comprising: an uphill section of pipeline which, in use, carries a gravitationally stratified flow of a first liquid and a second denser liquid, whereby the second liquid forms a sump extending uphill from the foot of the uphill section, and an interface between the first and second liquids on the uphill section is inclined from the horizontal; an extraction port in the pipeline for extracting the second liquid from the sump; and a sensor arrangement on the uphill section for sensing the position of a downstream tail of the sump, the length of that portion of the uphill section over which the position of the sump tail is sensed by the sensor arrangement being at least a distance of 15D, where D is the internal diameter of the pipeline, wherein a rate of extraction of the second liquid at the extraction port can be controlled on the basis of behaviour of the sump tail; and the angle of inclination of the uphill section to the horizontal is in the range from 2° to 6°.