樹脂薄片電去離子應用於冷卻水軟化的效能評估

Performance Evaluation of Resin Wafer-Electrodeionization for Cooling Water Softening

林展兆(Zhan-Zhao Lin)

指導教授 ： 蔣本基

國立臺灣大學/工學院/環境工程學研究所/碩士(2018年)

https://doi.org/10.6342/NTU201801898

摘要

水與能源之間複雜的相互依存關係對於決策者未來在達到安全、可靠和可持續的水和能源供應提出了新的挑戰。冷卻系統是工業中耗水量最大的程序，這使得我們可以使用適當的處理技術來減少淡水的消耗。藉由重複使用再生水進行冷卻可以減少冷卻水塔的排放量且同時減少補充水的使用量及抽水對環境和水生生物的影響。本研究使用樹脂晶圓電去離子（RW-EDI）技術來對冷卻水進行軟化進而達到水回收再利用。樹脂晶圓電去離子是將傳統的離子交換樹脂利用黏著劑使其成為多孔材料，這可以減少電去離子組裝和維護所需的勞力。
在這項研究中，進行了樹脂床的導電度和電流路徑測定，結果顯示在低濃度時有樹脂床可以使得其導電度上升大約兩個數量級並利用多孔-柱塞流模式找出液體、固體和固體-液體三種路徑的比例，同時也評估了樹脂晶圓電去離子模組的極限電流密度，以用於進一步的實驗設計。透過改變樹脂配比、施加電壓和表面流速對使用樹脂晶圓電去離子對冷卻水軟化的去除效率與能源消耗、產量和電流效率進行了評估。冷卻水軟化（從625處理至70毫克每升碳酸鈣硬度）平均能耗為0.033-0.336千瓦小時每立方公尺，產量為12.67-29.64升每小時每平方公尺。另外不同比例的晶片樹脂配方可以更有選擇性地移除不同離子。我們使用反應曲面法來最佳化不同操作情境，以拿來做冷卻水塔的質量分析。通過比較排放水後處理和補充水前處理的能耗和環境衝擊點數，我們可以發現同時進行排放水後處理和補充水前處理是冷卻塔處理的最佳程序。

關鍵字

冷卻水 ； 硬水軟化 ； 樹脂薄片電去離子 ； 補充水 ； 排放水 ； 生命週期評估

並列摘要

The complex interdependency between water and energy poses new challenges for policy makers to achieve a safe, secure and sustainable supply of water and energy in the future. Cooling systems are the most water-intensive process in industrial, presenting significant opportunities to reduce the withdrawal and consumptive use of fresh water. Reuse of impaired water for cooling can minimize freshwater withdrawal and decrease water contamination and withdrawal-related impacts on aquatic life and the environment. A robust ion-exchange resin-wafer electrodeionization (RW-EDI) technology was used to demonstrate for cooling water softening. Immobilizing the conventional ion-exchange resin into porous material which significantly reduced the service labor for assembling and maintenance.
In this study, the conductivity and current routes of resin bed were measured. The conductivity is increased by more than two orders of magnitude in low concentration and the porous-plug was applicated to defined the ratio of the interstitial solution, solid, and interstitial solution-solid pathways. The limiting current density was evaluated to understand the electrochemical properties of RW-EDI stacks for further experimental design. The removal efficiency for cooling wastewater softening using RW-EDI was evaluated along with energy consumption, productivity and current efficiency by several key operating conditions, including resin-wafer preparation, applied voltage and superficial velocity were selected through experimental design. Average energy consumption is 0.033-0.336 kWh/m3 and productivity is 12.67-29.64 L/hour/m2 for cooling wastewater softening (hardness: 625 to 70 mg/L as CaCO3). In addition, different proportions of wafer resin formulations can more selectively achieve optimized removal efficiency and energy use. Using response surface methodology to optimize the process for the cooling water tower mass balance analysis. By comparing the energy consumption and the endpoints from life cycle assessment of the mega and blowdown water of softening, we can find out the blow-down water post-treatment and the make-up pretreatment parallel is the best procedure for cooling tower treatment.

並列關鍵字

Softening ； Cooling Tower ； Resin-Wafer Electrodeionization ； Make-up water ； Blowdown water ； Life Cycle Assessment

參考文獻

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