Abstract: A combined technologies of high speed electrical desalting technology and AC/DC electric desalting technology were originally used in Petrochina Dagang Petrochemical Company electrical desalting device with a capacity of 5 Mt/a. However, the salt and water content was unqualified. After revamping with dual oil inlets & dual electric fields technology, the salt and water content in crude oil treated is less than 3 mg/L and 0.2%, respectively with thequalified rate of 100%. The oil content in discharged sewage is less than 150 mg/L, the qualified rate is 95%-100%. The calcium content in oil treated is reduced to less than 10 μg/g when the dosage of decalcifing agent is 25-35 μg/g.

Key words: dual oil inlets, dual electric fields, electric desalter, electric dehydrator