利用超音波換能器處理溫泉管線中碳酸鹽結垢之可行性研究

The Feasibility Study of Ultrasound Transducer Applied to Decarbonating Process in Hot Spring Pipeline System

台灣地區溫泉泉質種類繁複不一，但大致可分為以氯離子為主的氯化物泉、以碳酸根離子為主的碳酸氫鹽泉、以硫酸根離子的硫酸鹽泉，其中又以含碳酸根離子成份的泉質，為主要之溫泉成份。而溫泉水在管線輸送之過程，容易因富含礦物質之泉質造成管線、儲存設備結垢之情形；而目前最常見之結垢抑制辦法為添加複磷酸鹽類，作為結垢物之抑制、清除，但由於其成份含有氮、磷，一但排入水體，亦會造成水體負擔，影響生態平衡。緣此，本研究以物理性之方式處理溫泉管線結垢的問題，利用超音波技術所產生之物理性效應，在不同反應條件下，進行一系列之實驗及可行性之探討。本實驗之設計以人工調配之模擬溫泉水樣（含過飽合之鈣離子及碳氫根離子），設定在不同溫度及流速下，運用超音波換能器處理，觀察系統中水樣之pH值變化，作為判斷在不同參數設定下結垢與否之依據；此外，將實驗（反應）前後之水樣，進行鈣離子濃度之分析，並依其量化數據探討該技術應用於溫泉結垢抑制之效果。實驗結果顯示：循環系統在低流速(0.5 L/min)時，陰陽離子間有較穩定之接觸作用，使其結垢物生成較穩定，較易產生結垢及沉澱之現象；增加流速(1.0L/min)時，實驗結果則相反：另外，循環系統在高溫(45℃)時，因溶解度較低溫(25℃)時為大，水樣中之陰陽離子易以離子型態存在，可減緩水樣結垢物生成及沉澱時間。此實驗結果亦與實地查訪時觀察之結果相互符合：當溫度越高時，溫泉水體較不易出現結垢物之沉澱現象。超音波換能器系統抑制結垢物生成之結果顯示：受溫度及流速之影響，其震盪處理效應於低溫及低流速下較具抑制成效；然於高溫及高流速狀態時，其抑制效益較不明顯。因此，本研究建議之最佳操作條件為：超音波換能器系統於頻率為20kHz，功率為5W，在低溫(25℃)、低循環流速(0.5L/min)之條件下最具處理成效。本研究之實驗結果雖提供其學術基礎，為求研究成果之精確及完善，仍需更多之實場量化數據作為佐證，以有效提供溫泉產業於實場環境中建立結垢處理之平台，解決業者長期以來所面臨之問題。

There were three types of hot spring water in Taiwan, including chlorine salt type, carbonate type and sulfate salt type. When the hot spring water was delivered by pipeline system, the carbonate was easily precipitated in the pipeline and storage system, which considered as an essential problem for the owners of hot spring industry. These scaling problems corroded and damaged the pipes, leading the potential explosion problems. The major treatment methods were adding the chemical agents that contained the phosphorous and nitrate to inhibit the scaling, which caused the serious eutrophication problems in our natural environment. Replacing the pipes frequently was considered as a way to solve problems and free for chemical pollutants. However, the maintenance cost was huge and the wasted pipes were considered as an environmental issue. Therefore, in order to solve scaling problems with green technologies, this study applied ultrasound energy to the simulation process of hot spring delivery system. The increase/decrease of pH values were determined and the before/after concentrations of calcium ion were analyzed. Thus, the potential formation mechanisms of scaling in hot spring water and the performance of ultrasound assisted inhibition process were carefully exam med. The experimental results indicated that the cations and anions were easily collided to form the precipitations under the low recirculation flow rate and the calcium maintained in low concentration. Inversely, m high recirculation flow rate, the calcium ion existed in higher concentration. When the temperature changed in hot spring recirculation system, similar variation trends with flow rate were also confirmed. Moreover, higher temperature m spring water resulted in higher calcium concentrations remained. Thus, low flow rate and temperature could form a stable cations and anions collision reaction in hot spring water which resulted in high opportunity of scaling problems. The performance of ultrasound assisted inhibition process: The results indicated that ultrasound assisted inhibition process of scaling problem was depended with flow rate and temperature. When the control system was under lower flow rate and temperature, the performance functioned well in inhibiting the scaling problems. However, the performance was not obvious under higher flow rate and temperature. The optimized operation conditions were confirmed at low temperature (25℃) and low flow rate (0.5L/min) under ultrasound frequency of 20kHz with 5 w energy. The experimental results of this study are insufficient to conclude the optimization control conditions of ultrasound assisted inhibition process, which needs further researches and studies to fulfill the requirements.