氯碱工业盐水精制工艺优化

发布时间：2018-05-29 12:25

本文选题：盐水精制 + 优化　；参考：《山东大学》2017年硕士论文

【摘要】：氯碱工业是基础化工工业之一,在经济发展中具有重要地位,对国防建设和经济具有重要作用。氯碱工业经历了苛化法、水银法、隔膜法、离子膜法等工业方法,无论何种生产方式,电解过程中使用的饱和盐水质量尤为重要,精制盐水的质量直接影响到装置的安全高效运行和下游产品质量。盐水精制一般采用添加精制剂碳酸钠、氢氧化钠及氯化钡溶液,与杂质反应生成不溶沉淀物,通过澄清、两级过滤、金属离子吸附,产出满足电解装置运行的合格精制盐水,保证下游装置的稳定运行,但也存在许多问题。本论文针对盐水精制工艺装置存在的问题,从减少装置废水产生及排放量、精制工艺改造等方面入手,进行了较为系统的研究,优化了工艺,并在齐鲁石化公司氯碱厂进行了实施,实现了装置的长周期安稳运行。1.原盐质量的优化调整盐水精制工艺所使用的原料——原盐的质量直接影响到精制盐水的质量,在以往的盐水精制工艺生产中,控制好进厂原盐质量一直是一项重点工作,原盐各项质量指标必须合格才能正常使用。其中,原盐的钙镁离子含量比为重点控制指标。一直以来,所用原盐钙镁比值控制在大于1.5,在考察了原盐钙镁比对精制盐水的影响后,结合装置实际运行情况,确定了原盐钙镁比值最佳范围为1.5～3,为稳定盐水精制装置运行提供了依据。2.装置"水平衡"工作针对氯碱行业实际生产情况,对装置所产生的工业废水、生产废水的水质、走向等进行研究论证,并与实际生产用水进行对比,进行了一系列工艺优化和技术改进,最终实现了部分外排水用于工艺生产、过盛废水暂存等,逐渐使盐水工艺生产趋于了 "水平衡",解决了困扰装置的"水过剩"问题,最终实现了装置废水"零排放"。3.脱除硫酸根工艺改造对脱除硫酸根工艺进行改造,不再使用高毒危化品氯化钡,改为纳滤膜过滤的工艺,消除了原始设计工艺中,使用氯化钡所带来的运行成本高、盐水澄清桶运行不稳定、盐泥压滤工序负荷高等问题,废物排放大幅降低,装置运行更加稳定,经济和环境效益明显。4.延长螯合树脂塔运行周期开发新技术,在盐水中添加聚酸盐溶液,经石墨电极后,释放渗透液,延长了二次盐水精制的螯合树脂塔运行时间,由原设计的48小时提高至240小时,减少了树脂塔再生用盐酸、烧碱和纯水用量,降低了生产成本,减少了废水外排量,优化了水平衡工作。
[Abstract]:Chlor-alkali industry is one of the basic chemical industry, which plays an important role in economic development and national defense construction and economy. The chlor-alkali industry has experienced many industrial methods, such as caustic process, mercury process, diaphragm process, ion membrane process and so on. Regardless of the production mode, the quality of saturated salt water used in the electrolysis process is particularly important. The quality of refined brine has a direct impact on the safe and efficient operation of the plant and the quality of downstream products. In brine refining, sodium carbonate, sodium hydroxide and barium chloride solution are generally added to produce insoluble precipitates by reacting with impurities. Through clarification, two-stage filtration and metal ion adsorption, qualified refined brine is produced to meet the operation of the electrolytic unit. Ensure the steady operation of the downstream device, but there are also many problems. In this paper, aiming at the problems existing in brine refining process, a systematic study has been carried out on the aspects of reducing the production and discharge of plant wastewater and reforming the refining process, and the process has been optimized. The plant was implemented in the chlor-alkali plant of Qilu Petrochemical Company, and the long period stable operation of the plant was realized. The quality of raw salt used in brine refining process has a direct impact on the quality of refined brine. In the previous brine refining process, it has been a key task to control the quality of raw salt in the former brine refining process. Each quality index of raw salt must be qualified to be used normally. Among them, the ratio of calcium to magnesium ion of raw salt is the key control index. All the time, the ratio of raw salt calcium to magnesium has been controlled to be greater than 1.5. After investigating the effect of raw salt calcium magnesium ratio on refined brine, the actual operation of the unit has been studied. The optimum range of Ca / mg ratio of raw salt is 1. 5 ~ 3, which provides a basis for the operation of a stable brine refining unit. The "water balance" of the plant is aimed at the actual production situation of the chlor-alkali industry. The industrial wastewater produced by the plant, the water quality and the trend of the wastewater are studied and demonstrated, and compared with the actual production water. A series of process optimization and technical improvement have been carried out. Finally, part of the external drainage has been realized in the process production, and the waste water has been stored temporarily. The process of brine production has gradually tended to "water balance", which has solved the problem of "water surplus" in the troubled equipment. Finally, the "zero discharge" of plant wastewater was realized. The sulphate removal process was modified to remove sulphuric acid radical. Instead of using barium chloride, a highly toxic and dangerous chemical was replaced by a nanofiltration membrane filtration process, which eliminated the high operating cost brought by the use of barium chloride in the original design process. The operation of brine clarifier drum is unstable, the load of salt sludge pressure filtration process is high, the waste discharge is greatly reduced, the operation of the unit is more stable, and the economic and environmental benefits are obvious .4. A new technology was developed for prolonging the operation period of chelating resin tower, adding polyacrylate solution to brine, releasing permeate after graphite electrode, prolonging the operation time of chelating resin tower with secondary brine refining, from 48 hours designed to 240 hours. The amount of hydrochloric acid, caustic soda and pure water for regeneration of resin tower was reduced, the production cost was reduced, the discharge of waste water was reduced, and the water balance was optimized.
【学位授予单位】：山东大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TQ114.261

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