Study On Desalination For Crude Oil Based On Ethylene Glycol Extraction Coupling With Electric Desalination

Deterioration of crude oil quality is becoming more and more serious.Many traditional processes for desalination and dehydration failed to make salt content in crude oil meet industrial standard.And solvent extraction has become an emerging technology,making full use of its high salt solubility and large density over oil,which separates oil and solvent and leads to crude oil desalination and dehydration.However,this process is also facing with serious emulsification problem.Based on high salt solubility of ethylene glycol(EG)and the similarity-intermiscibility theory between EG and water,this paper innovatively combined EG extraction with electric desalination.It was a new technology process which replaced traditional electric desalination with water and demulsifier.Firstly,effect of high field intensity,low field intensity,temperature,residence time and initial salt content on desalination rate were investigated.It was found that salt content after desalination reached 7.45 mg/L and desalination rate reached 83.8%.The optimum condition was high field intensity=1000 V/cm,low field intensity=500 V/cm,temperature=120?,sedimentation time=60 min,residence time at high field intensity=10 min,residence time at low electric intensity=20 min.Additionally,transmittance rate,rheological properties,infrared spectrum and optical microscopic analysis were done to study the demulsification effect of crude oil after electric field.Light transmittance rate determination for Shengli oil showed that there was no absorption peak at 200 to 800 nm.Stability of emulsion was better after higher field intensity in 35 hours.Rheological properties determination showed that viscosity kept constant when shear rate increased.Its shear force showed a linear change with shear rate which showed wonderful Newtonian fluid properties.At last,this paper discussed the force effect of EG droplets diameter in electric field and solvent recycle process.Calculated results showed that as electric field intensity increased,the diameter of droplets it could deal with turned to be smaller and the critical coalescence diameter was smaller.Aspen plus simulation showed EG mole fraction was 0.96.The sensitivity analysis of temperature showed when temperature approached boiling point of ethylene glycol,the more fraction of ethylene glycol existed a maximum.And the pressure sensitivity analysis showed 1 bar was best.