本論文研究係以傳統化工製造業為例，所評估之案例工廠以共沸蒸餾方式將製程所產生之廢異丙醇溶液回收提濃再利用，為使三相蒸餾塔之異丙醇產品濃度得以符合現場脫水置換使用，先以成品濃度作為應變數，其餘如進料流量、迴流流量、迴流液位、主塔蒸氣、主塔控溫、塔頂溫度、塔底溫度、出料流量等操作參數為自變數，藉由Statistica 統計軟體來分析操作參數與成品濃度之關聯性。分析結果發現，迴流液位及迴流流量係對產品的濃度較具解釋力，與文獻結果相符合，但塔底溫度更是本研究所發現需要控制的重要參數。 為提升業界之投資意願，在論文研究過程中，亦嘗試以量化之方式提出其成本效益，分析結果顯示，依所評估工廠之產能計算，每個月可省下約722.4萬元之原料採購費用，2個月即可將建構成本攤提，表示此投資是符合經濟效益的。而在環境效益方面，由於廢溶劑的回收循環再利用，除了降低原料端的礦物開採量，相對也減少了車輛配送次數，另一方面亦使原廢水COD平均值由7120 mg/L降為1258 mg/L，提升了案例工廠之廢水處理效能，突顯此投資是符合循環經濟之概念。為避免不肖業者的違法情事，期以本研究之評析結果，鼓勵業者做好源頭減廢及資源再利用，一同降低環境之負荷。 ;This thesis evaluates the recycle of isopropanol from a chemical manufacturer from aspects of cost and environmental protection. Wasted propanol was concentrated and recycled by azeotropic distillation using the three-phase distillation tower. The recycled isopropanol will be returned in the manufacturing process as source materials. The correlations of input flow rate, returned flow rate, returned fluid level, main tower vapor pressure, tower top temperature, tower bottom temperature to the concentrated isopropanol were examined by Statistica. The results showed that returned fluid level and returned flow rate are important operating factors for distillation of isopropanol, which agrees with the literatures. It is also found that the tower bottom temperature is the most control factor for distillation of isopropanol. The cost of recycle of distillation of isopropanol by the three-phase distillation was analyzed. The analysis showed that the construction fee is about the cost of new isopropanol for 2 months. The decrease in the cost for new isopropanol is about 7.22 million per month.Also, as the wasted isopropanol was concentrated and returned to the manufacturing process, the mining of resource, transportation of resources, and energy used as well as waste generation for synthesize isopropanol are limited. Moreover, the chemical oxygen demand of the wastewater is significantly reduced (i.e. 7120 mg/L to 1258 mg/L) and ease the burden for wastewater treatment. This work shows that recycle of isopropanol is a sustainable strategy, which not only leads to cost-down but also helps to protect the environment.
