SEPARATOR FOR DESALTING PETROLEUM CRUDE OILS HAVING RAG LAYER WITHDRAWAL

摘要

An improved separator for desalting petroleum crude oils which may be operated in a continuous manner under automatic control; the improved desalter is therefore well suited to modern refinery operation with minimal downtime. A portion of the emulsion layer is withdrawn from the desalter through external withdrawal ports according to the thickness and position of the emulsion layer with the selected withdrawal header(s) being controlled by sensors monitoring the position and thickness of the emulsion layer. The withdrawn emulsion layer can be routed as such or with the desalter water effluent to a settling tank or directly to another unit for separation and reprocessing.

主权项

1. A petroleum desalter which comprises:
a desalter vessel having a feed inlet for admitting a mixture of crude oil to be desalted with desalting water to form (i) a settled water layer containing salts dissolved from the oil in the lower portion of the vessel, (ii) a settled supernatant desalted oil layer in the upper portion of the vessel and (iii) an emulsion layer formed from the oil and the water between the settled water layer and the settled oil layer, a water outlet conduit at the bottom of the vessel for removing water from the water layer, an oil outlet conduit at the top of the vessel for removing desalted oil from the oil layer, a plurality of vertically spaced emulsion outlets for removing emulsion from the emulsion layer, a level sensor system to indicate a lower interface between the top of the water layer and the bottom of the emulsion layer and an upper interface between the top of the emulsion layer and the bottom of the oil layer, a water outlet control valve in the water outlet conduit operable by the level sensor system to regulate the water outlet control valve in accordance with the water level indicated by means of the sensor so that the bottom of the emulsion layer is maintained above a minimum water level, an emulsion outlet valve on each of the emulsion outlets operable by the level sensor system to regulate the emulsion outlet valve on each of the emulsion outlets in accordance with the emulsion level indicated by the level sensor system so that at least one of the emulsion outlet valves is opened to remove emulsion from the vessel when the top of the emulsion layer in the vessel rises to a maximum emulsion level.