梳型共聚物的相对分子质量调控及其对JENM原油的降凝效果

Molecular Weight Control of Comb Copolymer and Its Mechanism of Freezing Point Depressing on JENM Crude Oil

为降低高蜡型JENM原油的输送成本,合成了丙烯酸十八酯-丙烯酸二十二酯-马来酸酐梳型共聚物降凝剂,考察了降凝剂相对分子质量对降凝效果的影响,并通过优化反应条件实现对聚合物相对分子质量的调控,研究了加剂前后JENM原油的析蜡特性和蜡晶形貌的变化。研究表明,随着反应温度升高和反应溶剂用量增加,降凝剂的平均相对分子质量减小;随着引发剂用量的增加,降凝剂的平均相对分子质量先增大后减小。丙烯酸十八酯-丙烯酸二十二酯-马来酸酐降凝剂的平均相对分子质量约为14000时对JENM原油的降凝效果较好,典型优化合成条件为:反应温度100℃、溶剂用量77%、引发剂用量为单体质量的1%,合成的降凝剂加剂量为0.3%时,JENM原油凝点由30℃降至17℃,降幅为13℃;30℃时黏度由9.12 Pa·s降至2.24 Pa·s,降黏率为75%,显著改善了JENM原油的低温流动性。结合DSC和显微分析发现,降凝剂的加入使JENM原油析蜡点和析蜡峰温降低,凝点处析蜡量增加。降凝剂的极性基团抑制了蜡晶生长,促进了蜡分子的分散,使晶种在更低温度才开始析出。同时,由于蜡晶更加细小,析蜡量较大时才使原油失去流动性,从而有效降低了原油凝点。图11表2参18。

In order to reduce the transportation cost of high wax type JENM crude oil,the octadecyl acrylate-docosyl acrylate-maleic anhydride comb copolymer freezing point depressant(FPD)was synthesized,the influence of the molecular weight of the FPD on the freezing point depressing effect was studied,and the regulation of the molecular weight of the copolymer was achieved by optimizing the reaction conditions.The characteristic of paraffin precipitation and morphology of paraffin crystal of JENM crude oil with/without the synthetic FPD was investigated.It was found that the average molecular weight of the synthetic FPD decreased with the increase of the reaction temperature and the amount of the solvent,and increased first and then decreased with the increase of the dosage of the initiator.The octadecyl acrylate-docosyl acrylate-maleic anhydride copolymer freezing point depressant had a better freezing point depressing effect on JENM crude oil when the average molecular weight was about 14000.Typical optimum synthetic conditions were the reaction temperature of 100℃,the solvent concentration of 77%and the initiator dosage of 1%.By adding 0.3%FPD synthesized under these conditions,the freezing point of JENM crude oil reduced from 30℃to 17℃with the decreasing amplitude of 13℃;the viscosity at 30℃decreased from 9.12 Pa·s to 2.24 Pa·s with the viscosity reduction rate of 75%,as a result,the low temperature fluidity of JENM crude oil was significantly improved.Differential scanning calorimetry and microscopic analysis showed that the addition of the FPD reduced the paraffin precipitation point and the paraffin peak temperature of JENM crude oil,and increased the paraffin precipitation amount at the freezing point.The polar group of FPD inhibited the growth of paraffin crystals,promoted the dispersion of paraffin molecules in crude oil,and made the paraffin seed crystals start to precipitate at lower temperatures.Besides,since the paraffin crystal was finer,the crude oil lost fluidity when the amount of paraffin is larger,thereby effectively reduced the freezing point of the crude oil.