Graphical strategies for design of evaporation crystallization networks for environmental wastewater applications

This paper introduces graphical strategies for the design of an evaporation/crystallization network for ternary wastewater environmental applications. Sources, sinks and other streams are located on a ternary composition diagram. While a source is any wastewater stream that has the potential to be recycled, a sink is any unit in the process that can accept sources. The proposed methodology is extremely simple to understand and implement, as it only requires basic solid-liquid phase equilibria data and uses lever arm principles to generate alternative process designs. Geometric constructions are carried out on the ternary composition diagram and the respective lever arms are used to determine intermediate flow rates in the evaporation/crystallization network. The relative locations and flow rates of the sources and sinks under consideration, as well as the unique shape of the solid-liquid equilibrium, drive the design of the separation (via evaporation/crystallization) network. Some generic structures are proposed for a typical evaporation and crystallization network. Once the general problem statement has been defined, special cases consisting of a single source-single sink, single source-two sinks and two sources-single sink are described. These special cases are representative of commonly occurring industrial wastewater design problems. Several graphical insights are listed that allow one to represent evaporation and crystallization operations on a ternary triangular composition diagram and avoid mathematical complexity. The possibility of bypassing a part of the initial feed streams is also considered. Certain feasible composition regions are identified on the ternary composition diagram for cases dealing with multiple sources and sinks. The methodology is useful in pre-screening and eliminating certain sources/sinks and is readily applicable to cases with lower number of sources and sinks. A case study involving the ammonium nitrate manufacturing process is included to demonstrate the broad applicability and value of the proposed approach.     

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抛丸处理在钢铁冷锻加工中的应用

钢铁冷锻加工中的磷化工序一般采用酸洗法去除毛坯上的氧化膜。现介绍用抛丸处理工艺替代酸洗方法,可以大幅度减少工业污染,降低生产成本,提高工艺质量。     

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我国矿产资源的现状及保护对策

本文着重讲述了我国矿产资源的特点,全面分析了我国矿产资源的现状,并 提出缓解矿产资源危机的一些对策。     

重庆城区地貌灾害的发展趋势及减灾研究

根据对重庆城区20世纪80年代以来发生的地貌灾害的分析研究，认识到其地貌灾害的成因及变化趋势，即时间上的周期性、空间上的分散性、地域上的转移性，并针对其发展趋势提出了相应的防治措施。     

秦皇岛市主要环境问题及控制对策

本文以详实的数据阐明了秦皇岛市气、水、声、生态环境质量方面存在的问题。进一步从生产力空间布局、产业结构、能源结构、城市环境基础设施、可持续发展观念五个方面分析了环境问题的成因。最后提出了调整产业结构、加强环境基础设施建设、加大环境综合整治力度、加强生态保护四项措施来解决存在的环境问题,对秦皇岛市的环境发展有一定的指导意义。     

四川省酸性降水范围,趋势预测及其对农作物,蔬菜生长影响估损

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