Abstract: Excessive sodium content in crude oil will lead to subsequent FCC catalyst poisoning. This paper analyzed the problem of abnormally high sodium content in de-salted crude oil of a refinery. In order to solve the problem, a sodium removal agent was developed. The effect of the sodium removal agent on sodium removal rate and on the demulsification was investigated. Based on the laboratory experiments, the agent was applied in a desalination unit. The results showed that the excessive sodium content in crude oil after electric desalination was caused by the excessive sulfonates used as crude oil recovering agent in oil field. The addition of sodium removal agent can break the equilibrium of petroleum sodium sulfonates distribution between the oil phase and water phase, and makes more sulfonates entering into the water phase, thus decreasing the sodium content in desalted crude oil. The industrial test in No.2 electric desalting unit showed that the sodium removal rate increased from 75.7% to 84.2% with the addition of the sodium removal agent.

Key words: petroleum sodium sulfonates, sodium removal, electric desalting, demulsification