混凝—超滤膜法用于乳化油分离的过程研究

发布时间：2018-08-29 11:00

【摘要】：目前我国大部分油田的开采已进入高含水后期开采阶段,原油含水率在30%～80%左右,有的甚至高达90%以上。由于每年产生的采油废水量巨大,而且油田采出水的成分及性质极其复杂,传统的油田采出水处理工艺已不能满足回注、回用或外排的要求。因此本文提出了利用混凝-超滤膜法联用的工艺来处理油田采出水。本课题主要考察混凝-超滤膜法联用工艺处理油田采出水中乳化油的效果。首先通过超声波法制得颗粒分布均匀,较小且稳定的乳化液。然后选用三种混凝剂Al2(SO4)3,FeCl3,AlCl3用于预处理过程,通过改变混凝剂用量和进料液性状来筛选出效果优异的混凝剂,并对超滤膜在处理过程中操作参数的选择及膜的污染情况进行了研究。研究结果表明三氯化铁对处理一定范围内pH值和温度的油田采出水有更好的适应性,对浊度及TOC(总有机碳)的去除效果也最好,对TOC的去除效率可以达到96%以上,但是TOC的最终含量都在23 mg/L以上。通过对比实验前后膜通量、TOC含量以及浊度值的变化,发现混凝-超滤膜法的联用对TOC的去除效率可以达到99%以上,可以使得TOC的最终含量降低到13 mg/L以下,达到油田回注水的水质要求。通过SEM,EDS等表面微观分析手段,发现混凝-超滤膜的联用在很大程度上减轻了膜污染的程度,保证膜通量在一段时间内的稳定性。在膜的分离过程中,在线周期性反冲洗可以有效地去除可逆性污染物沉积层,减缓膜的污染程度。本文采用每运行20min后再进行反冲洗60s的在线反冲洗方式进行实验,结果表明周期性的在线反冲洗可以降低水通量下降的速度,保证膜通量在一段时间内的稳定性。
[Abstract]:At present, the exploitation of most oil fields in our country has entered the stage of high water cut in late stage, the water cut of crude oil is about 30% or 80% or even up to 90%. Because of the huge amount of oil recovery waste water produced every year and the complexity of the composition and properties of the produced water, the traditional treatment process of produced water in oil field can not meet the requirements of injection, reuse or discharge. Therefore, a combined coagulation-ultrafiltration process is proposed to treat oilfield produced water. The purpose of this paper is to investigate the effect of coagulation-ultrafiltration process on emulsified oil in oilfield produced water. First of all, the particle distribution is uniform, small and stable emulsion is obtained by ultrasonic method. Then three kinds of coagulant Al2 (SO4) _ 3 FeCl _ 3O _ 3 ALCL _ 3 were used in the pretreatment process. The coagulant with excellent effect was screened by changing the dosage of coagulant and the characteristics of feed liquid. The selection of operating parameters and membrane fouling during the treatment of ultrafiltration membrane were studied. The results show that ferric chloride has better adaptability to treating produced water with pH value and temperature in a certain range, and the removal efficiency of turbidity and TOC (total organic carbon) is the best, and the removal efficiency of TOC can reach more than 96%. But the final content of TOC was above 23 mg/L. By comparing the changes of membrane flux and turbidity before and after the experiment, it was found that the combined use of coagulation and ultrafiltration membrane could achieve more than 99% removal efficiency of TOC, and the final content of TOC could be reduced to less than 13 mg/L. Meet the water quality requirements of oilfield water injection. By means of surface microanalysis such as SEM,EDS, it was found that the combined use of coagulation-ultrafiltration membrane greatly alleviated the degree of membrane fouling and ensured the stability of membrane flux for a period of time. In the process of membrane separation, on-line periodic backwashing can effectively remove the reversible pollutant deposit and slow down the fouling degree of the membrane. In this paper, the experimental results show that periodic online backwashing can reduce the speed of water flux decline and ensure the stability of membrane flux for a period of time.
【学位授予单位】：浙江大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：X741

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