超音波泥沙濃度量測系統設計開發及應用冪次法於多種粒徑泥沙溶液濃度量測與律定

懸浮顆粒溶液系統廣泛的應用在水文學、生物、化學以及食品等方面工業。而超音波量測是一種快速、非侵入和即時反應的量測技術，可對大濃度範圍及粒徑的懸浮顆粒系統達成特性描述。本論文利用訊號在超音波液體中發射、傳遞、接收的過程，信號強度會因溶液中的顆粒而產生衰減，設計並開發三種針對不同環境需求的超音波量測設備，利用這樣的超音波訊號衰減特性可以提供即時的溶液濃度及顆粒分布情況。此設備之開發乃是結合本實驗室、本校水工試驗所及聲博科技公司之共同合作，本實驗室及台大水工試驗所負責提供超音波泥沙濃度量測特性資料及特別針對台灣特殊的水文環境與不同使用環境條件所適用的量測系統規格訂定，並由聲博科技公司針對量測系統探頭、電路、資料儲存與機身機構設計製作。本論文亦引用醫用超音波的系統律定法，運用於濃度對衰減訊號的律定上。使用冪次法主要目標為希望日後在改變探頭頻率或探頭間距等量測條件時可簡化量測系統律定過程，只需以清水衰減值做迴歸，便可直接套用至冪函數相關係數內，藉由相關係數來推算量測濃度便可簡化舊有濃度對衰減律定方式的繁雜過程並省下大量的工作時間。因此我們在實驗室中針對五種土樣：石門水庫庫底土樣、高嶺土、硅石粉、石英砂及市售土樣，進行一系列的實驗。並以組合粒徑方式模擬庫區粒徑的組合土樣，在1MHz、3MHz、5MHz、10MHz不同的探頭頻率探討超音波在不同泥沙濃度水溶液中衰減隨頻率變化的關係，並以冪函數關係式來迴歸求取相關係數，最後並以不同量測距離（20cm、35cm、46cm）下相互驗證所迴歸係數的重複性與可行性。論文中也藉由濃度對衰減律定量測結果來進一步討論頻率改變與量測距離改變對量測結果間的差異性比較。在2008年颱風期間運用超音波系統於石門水庫與曾文水庫庫區進行濃度監測，並事後在實驗室烘乾驗證比較。結果發現不論在不同距離或不同土樣情況下都可得到很好的冪函數迴歸結果，證明冪次法運用於超音波泥沙濃度量測的可行性。現場量測結果與烘乾比對誤差都在5%以內。

關鍵字

超音波量測；濃度；冪次法

並列摘要

Multiphase suspension systems are extensively used in hydrology, biochemistry, and the food industry. Ultrasonic spectroscopy is a rapid, on-line, non-invasive measurement technique for suspension characterization of different particle sizes and wide-ranging concentrations. In this thesis, three types of measurement systems have been developed and manufactured through the collaboration of our Lab, Hydrotech Research Institute, NTU, and Broadsound Corporation. The systems employ the launch, transmission, and reception of ultrasound signal in the liquid solution and the signal attenuation in the solution provides the systems the capability of real-time particle concentration measurement. Besides, the power law was also introduced in this paper to simplify system calibration for concentration versus attenuation. For different samples, the calibration results obtained by the power law are still valid while changing frequency and distant between probes. Once the function of power law for specific sample is experimentally determine, we can predict the sediment concentration only by calibrating pure water. Five samples, reservoir sediments, Kaolin, silica powder, quartz sand, and compose samples, were experimentally investigated. The operated ultrasonic frequencies were 1MHz, 3MHz, 5MHz and 10MHz, respectively. The repeatability and accuracy of power law function was confirmed by varying the distance between probes. The ultrasonic measurement systems have been employed successfully in the Shihmen and Tsengwen reservoirs during several typhoons in 2008. The results show that the power law obtains very good regression functions. The developed ultrasonic systems were verified through laboratory experiments and demonstrated that the overall error is within 5% through the field measurements in typhoons in 2008.

並列關鍵字

Ultrasonic measurement ； concentration ； power law

參考文獻

1. V. Stolojanu and A. Praksh, “Characterization of slurry systems by ultrasonic techniques”, Chemical Engineering Journal, vol. 84, pp. 215-222, 2001.

2. A. H. Harker and J. A. G. Temple, “Velocity and attenuation of ultrasound in suspensions of particles in fluids”, J. Phys. D: Appl. Phys, vol. 21, pp. 1576-1588, 1998.

3. A. B. Judith and S. G. Margaret, “Measuring fluid and slurry density and solids concentration non-invasively”, Ultrasonics, vol. 42, pp. 563-567, 2004

4. K. H. Andrew, E. C. Richard and J. W. David, “A wide-bandwidth ultrasonic study of suspensions: the variation of velocity and attenuation with particle size”, Journal of Colloid and Interface Science, vol. 168, pp. 339-348, 1994.

5. V. J. Stakutis, R. W. Morse, M. Dill and T. Bever, “Attenuation of ultrasound in aqueous suspensions”, The Journal of the Acoustical Society of America, vol. 27, pp. 539-546, 1955.

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超音波泥沙濃度量測系統設計開發及應用冪次法於多種粒徑泥沙溶液濃度量測與律定

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