工業廢水回收再利用效益評估:以石化工業中游廠為例

Benefit Assessment of Industrial Wastewater Reclamation : Case Study of a Mid-stream Petrochemical Plant

林承緯(Cheng-Wei Lin)

指導教授 ： 莊瑞鑫

元智大學/工程學院/化學工程與材料科學學系/碩士(2012年)

https://doi.org/10.6838/YZU.2012.00197

摘要

本研究以石化工業中游廠為例，研究「工業廢水回收再利用效益」，主要是回收屬有機廢水的廢水處理工場放流水，及屬無機廢水的冷卻水塔濃縮排放廢水與沖洗廢水，經綜合評估後已實廠為例進行探討，擬定出各種可行方案，以回收至工業冷卻水塔補充用水，而各方案需分別選擇適合的水質來源，其中水質導電度較高及含有大量硫酸根離子之有機廢水，則主要選用超過濾(UF)與逆滲透(RO)回收設備，無機廢水方面則主要選用倒極電透析(EDR)回收設備，水質來源確定後，接著估算出設備容量的需求，並分析各成本，最後以工程經濟學的學理來進行方案的成本分析與可行性分析，選出最佳可行方案。
就本研究最後結果可知，未來水價高於15.4 元/m3，且總產水率維持在64%以上的話，方案三：超過濾(UF)+逆滲透(RO)是最佳的方案，而且方案三可使目前整廠廢水回收率由6.7%，提高至31%，不僅可以降低用水成本，提升企業形象外，更對於未來水資源匱乏的世紀，能提早進行因應。
在工程經濟分析中的變數，確實需要隨時求證與追蹤最新的數據，才能在進行評估的過程得到一個最客觀的結果﹑例如利率與初設成本是會變動的，若不隨時更新，可能就影響判斷的準確性。
石化工業中游廠仍有許多可降低用水成本的方案，如雨水回收再利用、提升製程用水效率及用水管理，但是這些方案需要不同的處理方式，且用途也盡不同，當然也會產生經濟效益，所以當要投資這些方案的時候，亦可以先經過工程經濟的分析，來進行可行性判斷。

關鍵字

石化工業 ； 回收再利用 ； 倒極電透析 ； 逆滲透 ； 工程經濟

並列摘要

This research used a midstream plant of the petrochemical industry as a case study to examine the “effect of the recycling of industrial wastewater.” The focus was on discharged water from wastewater treatment plants specialized in organic wastewater treatment as well as concentrated discharged water and wash wastewater from cooling towers handling inorganic wastewater. After comprehensive evaluations were conducted on the plant, feasible plans were thus formulated to recycle the water to the cooling towers to supplement water usage. However, each plan needed to choose a suitable source of water. Among which, ultrafiltration (UF) and reverse osmosis (RO) recycling equipment were used for organic wastewater with higher electrical conductivity and greater number of sulfate ions while electro dialysis reversal (EDR) equipment was used for inorganic wastewater. After the water source was ascertained, the required capacity of the equipment was then calculated to analyze the costs. Finally, the best feasible plan was selected by applying theories of engineering economics to undertake cost and feasibility analyses.
The research results showed that Plan 3, namely ultrafiltration (UF) and reverse osmosis (RO), would be the best plan if the water price was higher than NT$15.4/m3 and the total water production rate was maintained at more than 64%. Moreover, Plan 3 could well increase the plant’s wastewater recycle rate from 6.7% to 31%.

並列關鍵字

Engineering Economy ； Petrochemical ； Reclamation ； Electro Dialysis Reversal ； Reverse Osmosis

參考文獻

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