Design Synthesis And Demulsification Performance Of Cationic Block Polyether Demulsifier

In this paper,a series of cationic block polyether demulsifier is designed and synthesized,which aims at improving oil recovery and treating oily water after demulsification.Mainly using ethylene glycol and epiglorohydrin as raw materials,boron trifluoride ether as catalyst,reaction temperature 20.0～50.0℃,stirring rate of 500 r/min,700 r/min,titration rate of 1.50g/min,2.00 g/min,Chlorine polyether EG-（ECH）₅and EG-（ECH）₁₀were synthesized by polymerization reaction.Diblock polyether and triblock polyether were synthesized by block polymerization with ethylene oxide and propylene oxide in high pressure reactor under the conditions of 110～130℃,（0.20±0.10）MPa and 10.9 g/min and 11.2 g/min respectively.Finally,cationic block polyether CBPD and LBPD series demulsifiers were produced by quaternization in trimethylamine aqueous solution.The turbidity point,HLB value and surface tension of aqueous solution of CBPD and LBPD series demulsifiers were determined.The influence of the structure of block polyether on its surface activity and hydrophilicity was studied.The results show that the turbidity point increases with the increase of the content of hydrophilic block.When the molar ratio of hydrophilic and oleophilic blocks is 1:1,the HLB value will increase with the increase of molecular weight of demulsifier.With the increase of the concentration of CBPD series and LBPD series demulsifier,the surface tension of the solution decreased,and when the concentration increased to 150 g/m L,which is CMC,the solution decreased to 41 m N·m^-1,showing good surface activity.The surface activities of CBPD-7～CBPD-9 and LBPD-7～LBPD-9 were superior to other demulsifiers in the same series.In order to study the demulsification performance of the synthesized cationic block polyether demulsifier,the dewatering performance and the purification performance of oily sewage were measured respectively.The demulsification properties of CBPD and LBPD series demulsifiers on O/W crude oil emulsions were studied.The results showed that under the conditions of demulsification temperature at 70.0℃,demulsification dosage at 150 mg/L and demulsification time at 2 h,The dehydration rate of CBPD-9 in CBPD series was up to92.86%,and that of LBPD-9 in LBPD series was up to 95.00%.Under the same demulsification conditions,the demulsification performance of the same series of three-block polyether demulsifier was superior to that of diblock polyether demulsifier.The experimental results show that LBPD series demulsifier has better purification performance than CBPD series demulsifier,and the demulsifier CBPD-9,CBPD-12,LBPD-9 and LBPD-12 have better purification performance than demulsifier OP-25.Among them,demulsifiers CBPD-9,CBPD-12,LBPD-9 and LBPD-12 can reduce the oil content of the extracted water phase to84.0 mg/L,76.0 mg/L,78.0 mg/L and 68.0 mg/L,respectively.The solid content of suspended matter is controlled in 10.2 mg/L,8.80 mg/L,9.80 mg/L,7.50 mg/L;At the same time,the median particle size can be reduced to less than 3.00μm.With the increase of cationic degree,the sedimentation time and transmittance will fluctuate greatly and there are extreme values.When the cationic degree is 23.81%,the sedimentation time is the fastest,which is 63 s.When the cationic degree is 22.20%,the transmittance is the highest,which is 80.20%.The oil content of sewage decreases with the increase of cation degree.