DESALTER SOLVENT EXTRACTION SYSTEM

摘要

An improvement in crude oil refining is disclosed wherein a desalter (50) is operated so as to produce an organics phase (12) of reduced salts content ready for feeding to a distillation step and an aqueous phase of high salts content. By withdrawing the organics phase (14) from a higher level relative to the rag layer in said desalter (50) and after a relatively longer residence time than in conventional desalting operations, substantially little if any of the rag layer's content from the desalter (50) is included in the withdrawn organics phase (12) and the latter is suitable for feed to a distillation step (64). The resulting heavily organics-contaminated aqueous phase is mixed with an extractant comprising a gas converted to a solvent-condition fluid state under critical or near-critical temperature and pressure conditions to provide substantially organics-free waste water (26) suitable for discharge and to form a fluid extract of organics (32) from which benzene and other oil fractions can be recovered.