化工进展 ›› 2022, Vol. 41 ›› Issue (4): 1834-1839.DOI: 10.16085/j.issn.1000-6613.2021-0731

• 能源加工与技术 • 上一篇    下一篇

基于臭氧与超声氧化降低页岩气压裂返排液COD

熊颖1,2(), 周厚安1,2, 熊钢1,2   

  1. 1.中国石油西南油气田分公司天然气研究院,四川 成都 610213
    2.页岩气评价与开采四川省重点实验室,四川 成都 610213
  • 收稿日期:2021-04-08 修回日期:2021-06-02 出版日期:2022-04-23 发布日期:2022-04-25
  • 通讯作者: 熊颖
  • 作者简介:熊颖(1981—),男,博士,高级工程师。E-mail:xiong_y@petrochina.com.cn
  • 基金资助:
    中国石油天然气股份有限公司科学研究与技术开发项目(2019F-31)

COD reduction treatment of flowback water from shale gas hydraulic fracturing based on oxidation with ozonation and ultrasound

XIONG Ying1,2(), ZHOU Hou’an1,2, XIONG Gang1,2   

  1. 1.Research Institute of Natural Gas Technology, PetroChina Southwest Oil & Gasfield Company, Chengdu 610213, Sichuan, China
    2.Shale Gas Exploitation and Evaluation Key Laboratory of Sichuan Province, Chengdu 610213, Sichuan, China
  • Received:2021-04-08 Revised:2021-06-02 Online:2022-04-23 Published:2022-04-25
  • Contact: XIONG Ying

摘要:

针对页岩气压裂返排液化学需氧量(COD)高,难以直接排放的问题,研究了臭氧氧化(O3)、超声氧化(US)和臭氧与超声联用氧化(O3+US)三种方式降低页岩气压裂返排液COD的效果。结果表明:O3+US因能产生更多的自由基而具有更好的降低COD效果。O3+US联用氧化返排液过程中,首先是臭氧直接氧化有机污染物生成醛酮等物质,然后再是自由基氧化降解,返排液颜色会出现特征变化。另外研究了水样pH、超声波功率、催化剂种类和加量、反应时间等因素对O3+US联用氧化降低COD的影响,结果表明其降低COD的效率随pH的增大而减小,随超声波功率的增大先增大后减小,随作用时间的延长而增大。综合考虑,推荐降低页岩气压裂返排液COD的氧化条件为:臭氧质量浓度42mg/L、pH为2.5左右、超声波功率800W、催化剂MnO2加量0.45g/L、反应时间100min,处理后COD降低68.17%。同时,降解动力学拟合分析显示MnO2催化下O3+US联用氧化降低页岩气压裂返排液COD的过程更符合二级动力学特征。

关键词: 页岩气, 压裂返排液, 臭氧, 氧化, 超声波

Abstract:

In order to solve the problem of high COD and difficulty in direct discharge of flowback water from shale gas hydraulic fracturing, three methods including individual ozonation, individual ultrasound, and ozonation-ultrasound combination (O3+US) were compared. O3+US had the best performance because it could produce much more radicals than the other two methods. During the O3+US treatment, firstly, the organic pollutants in flowback water could be oxidized directly to form aldehydes and ketones by O3, and then oxidative degradation of free radicals happened. At the same time, the color of flowback had the characteristic change corresponding to the process. The effects of pH, US power, catalyst type, catalyst dosage, and reaction time on COD reduction of O3+US were investigated. The COD reduction increased with decreasing pH and increasing reaction time, and increased firstly and then decreased with increasing US power. The recommended O3+US condition was as follows: O3 concentration 42mg/L, pH 2.5, US power 800W, catalyst MnO2 0.45g/L, and reaction time 100min. The COD reduction was 68.17% at the recommended condition. In addition, it was found that the degradation kinetics of organic pollutants in flowback water by O3+US was likely to be second-order kinetics.

Key words: shale gas, flowback water from shale gas hydraulic fracturing, ozone, oxidation, ultrasound

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