碩士 / 國立臺北科技大學 / 化學工程與生物科技系化學工程碩士班 / 106 / It is recognized that potable water and energy are gradually insufficient for human needs. To exploit sustainable resources, technologies have been developed to desalinate seawater and produce power using salinity gradient. Reverse osmosis (RO) is one of the major technologies for desalinating seawater, while pressure retarded osmosis (PRO) is a promising technology for power production. The RO desalination plant has the problems of extensive pump energy cost and brine discharge, which can be alleviated by hybridizing the RO process with the PRO process to become an integrated RO/PRO system. Naturally a question arises. Can the energy consumption of a RO desalination plant be fully covered by salinity power harvested from PRO in an integrated system, while at the same time the system has zero brine discharge? If possible, how should these two processes connect and what operational conditions does the hybrid system require? Unfortunately, the answers cannot be directly found in the literature.
Therefore, this study aims to investigate the integration of RO and PRO processes to realize a PRO-based stand-alone salinity power driven RO desalination plant with zero brine discharge. The “stand-alone” means that the hybrid system does not require external energy supply. Structural design, characteristics analysis, and performance optimization of the hybrid system will be carried out using systematic mathematical methods. based on previous research two simple hybrid systems (RO-PRO and PRO-RO) are proposed as the basis for the investigation. The hybrid system is analyzed as a thermodynamic cycle and the characteristic equations relating critical operational variables for the stand-alone condition are analytically derived to facilitate system-level analysis and optimization. A preliminary study reveals that the RO water recovery is low under the stand-alone operation. Therefore, approaches are further proposed to improve the RO water recovery, through the use of two-stage RO or PRO. For the approach, six innovative design configurations are proposed and analyzed. The RO water recoveries in the six configurations are maximized by solving an optimization model which optimally selects operating conditions, and then the best configuration can be identified. Furthermore, the effects of several design/operation variables on the optimization results will be discussed. The results show that the proposed six configurations, combined with two-stage pressure retarded osmosis and reverse osmosis (PRO-PRO-RO), have the best system water recovery and the minimum specific total membrane area (STMA). The two-stage reverse osmosis process can also slightly increase the system water recovery rate, but the STMA will increase, making it less advantageous than the two-stage pressure retarded osmosis.
| Identifer | oai:union.ndltd.org:TW/106TIT0506A067 |
| Date | January 2018 |
| Creators | Chun-San Chen, 陳鈞三 |
| Contributors | Jyh-Cheng Jeng, 鄭智成 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 114 |
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