炼油技术与工程 ›› 2023, Vol. 53 ›› Issue (10): 1-6.

• 加工工艺 •    下一篇

冷却结晶法回收乙烯废碱液中Na2SO4研究

谭向东, 王雪清, 周彤, 陈天佐, 马传军, 郭宏山, 李宝忠   

  1. 1.中石化(大连)石油化工研究院有限公司; 2.工业废水无害化与资源化国家工程研究中心
  • 收稿日期:2023-02-21 出版日期:2023-10-15 发布日期:2023-10-19
  • 作者简介:谭向东，工程师，博士，研究方向为水处理药剂及电极材料研发、高级氧化、废水资源化处理等。联系电话：0411-39699129,E-mail:hellotanxiangdong@163.com。
  • 基金资助:
    中国石油化工集团有限公司资助项目（321141）;

Recovery of sodium sulfate from spent caustic of ethylene by cooling crystallization method

Tan Xiangdong, Wang Xueqing, Zhou Tong, Chen Tianzuo, Ma Chuanjun, Guo Hongshan, Li Baozhong   

  1. 1.SINOPEC (Dalian) Research Institute of Petroleum and Petrochemicals Co., Ltd.; 2.National Engineering Research Center of Industrial Wastewater Detoxication and Resource Recovery
  • Received:2023-02-21 Online:2023-10-15 Published:2023-10-19

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摘要：

高盐废水的零排放和资源化是解决水污染和水资源短缺问题的重要途径之一，通过除油、脱碳、浓缩、冷却结晶过程，从乙烯裂解废碱中回收得到固体Na2SO4产品。实验结果表明，煤基活性炭可作为优良的油吸附剂，能去除94%以上的油。硫酸脱碳过程可使废碱液中Na2CO3及NaOH转化为Na2SO4,减少冷却结晶中杂盐的影响，提高Na2SO4产率。浓缩过程可以提高后期冷却结晶Na2SO4产品的产率，冷却结晶可以在很宽的温度范围内(1～14℃)得到具有较好结晶度的Na2SO4产品，且不会形成包括NaCl在内的杂盐，表明通过冷却结晶工艺回收Na2SO4具有可行性。本研究结果可为废碱液的零排放和资源化处理提供借鉴。

关键词: 冷却结晶法, 乙烯, 废碱液, Na2SO4, 总有机碳, SEM, XRD

Abstract:

Zero discharge and resourcelization of high-salt sewage is one of the most significant approaches to solve the problem of water pollution and shortage. Solid Na2SO4 product is recovered from spent caustic of ethylene cracking by oil removal, decarbonization, concentration and cooling crystallization process. The experimental results show that coal-based activated carbon can be used as an excellent oil adsorbent, capable of removing more than 94% of oil. The process of sulfuric acid decarbonization can convert Na2CO3 and NaOH in spent caustic into Na2SO4, reduce the influence of impurity salt in cooling crystallization and increase the yield of Na2SO4. The concentration process can increase the yield of Na2SO4 product in the later stage of cooling crystallization. Cooling crystallization can obtain Na2SO4 products with good crystallinity over a wide temperature range(1～14 ℃), without the formation of impurities including NaCl. This work provides a guiding significance for zero emission and resourcelization of spent caustic.

Key words: cooling crystallization method, ethylene, spent caustic, sodium sulfate, total organic carbon, SEM, XRD