高壓蒸氣輸送系統之動態模擬與分析

本研究旨在針對化學工廠中之高壓蒸汽系統之輸送進行深入動態分析。本研究將由最基本的統御方程式開始建立流體模型，其後在傳統隱式法的基礎下提出了迴圈式隱式法，此一迴圈式隱式法更為適合應用在大型蒸汽系統的數學解析方法。迴圈式隱式法在經過與特徵法的比較與分析後，確定了其適用性，因此本研究將此方法應用到蒸汽系統上。過去文獻主要研究大都侷限於單管系統的動態分析，但在實際工廠中，會面臨的還有更複雜的環狀系統。本研究中提出了將哈迪•克勞斯法與迴圈式隱式法進行結合的一個運算方法，使其可以用來分析與模擬環狀蒸汽分配系統的動態分析。最後將此種結合過後的方法應用到數個虛擬的簡單範例，與一個真實的大型石化廠案例。此種分析可以用來預測不同操作狀況下的波動情形，提供現廠人員操作的一個參考，亦可用於模擬不同操作方式下的優劣，對於提升高壓蒸汽管網的操作效益有莫大的助益。

關鍵字

蒸汽；氣相管線；動態分析；特徵法；隱式法；哈迪•克勞斯法

並列摘要

The mathematical models for unsteady pipeline networks play an important role in the design of petrochemical plants, hydraulic power machines, long distance pipelines, etc., and have become popular in these industry due to the development of high-speed computers. An iterative implicit method is proposed in this research to solve the continuity, momentum and energy equations in an unsteady, non-isothermal and compressible steam pipeline. The Newton-Raphson method is used as an algorithm to solve the finite-difference equations of a steam pipeline. The modified Hardy-Cross method is applied to the calculation of network system. A set of nonlinear equations have to be solved simultaneously in traditional fully implicit methods, which are inappropriate to be used in a complex network system. Hence, a sequentially iterative fully implicit method has been propounded to deal with the nonlinear equations. Several cases are completed by the presented iterative fully implicit method and the simulation results are compared with existing characteristics methods. For network systems, the present work proposes a method which combines the iterative fully implicit method that has been used in a single pipeline with the modified Hardy-Cross method and several examples are completed. The transient analysis of a network system is more practical than a single pipeline in a large refinery, therefore, the present study gives a simple method which can quickly have a deep look into the steam transient response.

並列關鍵字

Steam ； Gas Pipeline ； Transient Response Analysis ； Characteristics Method ； Implicit Method ； Hardy Cross Method

參考文獻

[4] Bender, E., Simulation of dynamic gas flows in networks including control loops. Computers & Chemical Engineering 1979, 3, (1–4), 611-613.

[5] Poloni, M.; Winterbone, D. E.; Nichols, J. R. In Calculation of pressure and temperature discontinuity in a pipe by the method characteristics and the two-step differential Lax-Wendroff method, American Society of Mechanical Engineers, Fluids Engineering Division (Publication) FED, 1987; 1987; pp 1-7.

[7] Fincham, A. E.; Goldwater, M. H., Simulation models for gas transmission networks. Transactions of the Institute of Measurement and Control 1979, 1, (1), 3-13.

[8] Thorley, A. R. D.; Tiley, C. H., Unsteady and transient flow of compressible fluids in pipelines-a review of theoretical and some experimental studies. International Journal of Heat and Fluid Flow 1987, 8, (1), 3-15.

[13] Kiuchi, T., An implicit method for transient gas flows in pipe networks. International Journal of Heat and Fluid Flow 1994, 15, (5), 378-383.

國際替代計量

高壓蒸氣輸送系統之動態模擬與分析

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