Investigation of mass and heat transport and sustainability of the novel thermally driven membrane distillation crystallization process

研究新型热驱动膜蒸馏结晶过程的质量和热传输及可持续性

• 批准号: 1236846
• 负责人: Tzahi Cath
• 金额: $ 22.28万
• 依托单位: Colorado School of Mines
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-09-01 至 2016-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1236846&HistoricalAwards=false
• 关键词: Investigation; mass; heat; transport; sustainability

1236846CathWhen considering one of the more popular desalination processes, reverse osmosis, practical water recovery in seawater desalination is hydraulically limited to approximately 60 percent, and in brackish water desalination, recovery is limited to approximately 80 percent by mineral scale formation. Restricted water recovery and increasing energy demand at higher recoveries might limit further improvement of currently used membrane desalination technologies. Distillation processes, and specifically membrane processes that utilize vapor pressure as a driving force, are not limited by the osmotic pressure of feed or brine streams, and might be a solution to overcome the limitations of current desalination processes. Thus, the main objective of this research is to comprehensively investigate heat and mass transport in novel membrane distillation crystallization processes in which water is sustainably desalinated from supersaturated feed solutions and minerals can be simultaneously recovered for beneficial use. The research focuses on measuring the rates of formation, size distribution, adhesion to membranes, and removal/harvesting of mineral crystals that form during desalination of water containing sparingly soluble salts. It also investigates the effects of operating conditions and environments on the sustainable production of purified water and minerals using the membrane distillation crystallization process. Controlled laboratory experiments will be carried out in which a rigorous scientific approach will be applied to identify, characterize, and quantify the individual and combined mechanisms controlling bulk and surface crystallization and their effects on heat and mass transport through the membrane. In particular, the focus of the research will be to identify the optimal operating conditions under which this hybrid desalination and mineral recovery process can be sustainably operated under supersaturated conditions to produce water and produce valuable mineral. Through the analytical methods and quantitative tools that will be developed as part of this research, improvements will be made to the current understanding of the fundamental principles and mechanisms involved in evaporation of water through scale layers followed by porous synthetic membranes. These will help the application of this knowledge in the modeling and design of small and large engineered systems.Limited water recovery in existing desalination processes is the cause for elevated operating costs of desalination. This research will address the global need to increase water availability through the constant improvement of technologies that produce water at higher quality, lower energy demand, using renewable sources of energy, and without harming the environment. Understanding the mechanisms of reversible and repeatable membrane fouling scaling when treating supersaturated solutions by thermally driven membrane processes will mitigate one of the main problems encountered in desalination of saline water. Ultimately, the goal of this research is to improve our ability to provide clean water at an affordable cost to the public in modern and developing countries. The results will also facilitate the design of better treatment processes to reduce the discharge of brines to the environment and increase the reliance on natural resources, such as solar energy, for desalination. The research and educational plan will support the participation of undergraduate and graduate science and engineering students, and specifically from underrepresented groups/minorities in research and education. The development of interactive lecture and hands-on activities, and the establishment of continued education programs for pre-college teachers will enhance the interests of their students in science, engineering, and the environment, and will hopefully direct more motivated students to pursue higher education in environmental engineering.

1236846Cath 当考虑一种更流行的海水淡化工艺（反渗透）时，海水淡化中的实际水回收率在水力上限制为约 60%，而在苦咸水淡化中，由于矿物质结垢的形成，回收率限制在约 80%。有限的水回收和较高回收率下不断增加的能源需求可能会限制目前使用的膜海水淡化技术的进一步改进。蒸馏过程，特别是利用蒸气压作为驱动力的膜过程，不受进料或盐水流的渗透压的限制，并且可能是克服当前海水淡化过程限制的解决方案。因此，本研究的主要目的是全面研究新型膜蒸馏结晶过程中的热和质量传递，其中水从过饱和进料溶液中可持续脱盐，并且矿物质可以同时回收以供有益使用。该研究的重点是测量含有难溶盐的水脱盐过程中形成的矿物晶体的形成速率、尺寸分布、膜粘附性以及去除/收获。它还研究了操作条件和环境对使用膜蒸馏结晶工艺可持续生产纯净水和矿物质的影响。 将进行受控实验室实验，其中将应用严格的科学方法来识别、表征和量化控制本体和表面结晶的单独和组合机制及其对通过膜的热和质量传输的影响。 特别是，研究的重点将是确定最佳操作条件，使这种混合海水淡化和矿物回收工艺可以在过饱和条件下可持续运行，以生产水和生产有价值的矿物。 通过作为本研究的一部分开发的分析方法和定量工具，将改善目前对水通过水垢层和多孔合成膜蒸发的基本原理和机制的理解。这些将有助于这些知识在小型和大型工程系统的建模和设计中的应用。现有海水淡化过程中有限的水回收是海水淡化运营成本升高的原因。 这项研究将通过不断改进生产更高质量的水、降低能源需求、使用可再生能源且不损害环境的技术来满足全球增加水资源供应的需求。 了解通过热驱动膜工艺处理过饱和溶液时可逆和可重复的膜污染结垢的机制将减轻盐水淡化中遇到的主要问题之一。 最终，这项研究的目标是提高我们以可承受的成本向现代和发展中国家公众提供清洁水的能力。 研究结果还将有助于设计更好的处理工艺，以减少盐水向环境的排放，并增加海水淡化对太阳能等自然资源的依赖。 研究和教育计划将支持本科生和研究生科学与工程专业学生的参与，特别是来自代表性不足的群体/少数群体的研究和教育。 互动讲座和实践活动的开展，以及大学预科教师继续教育计划的建立，将增强学生对科学、工程和环境的兴趣，并有望引导更多积极主动的学生接受高等教育在环境工程方面。