Mathematical Models of the Oil Fired Continuous Furnace
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摘要: 本文包括:(1)爐膛內鋼坯加熱數學模型;(2)最佳爐溫及最低燃耗在線模型。
采用一維模型,應用Hottel多層無限大氣層間的輻射熱交換計算方法,把各火焰射流的作用,當量地看作是夾在上下爐氣層之間的一個火焰層。它的平均溫度tf可以根據Ricou-Spalding射流吸入經驗公式,計算火焰和周圍爐氣間的質量交換,再按熱平衡方程把tf計算出來。鋼坯內部傳熱按一維導熱問題,用差分求解。
還建立了一個較簡單的爐膛傳熱仿真模型,據此求出各爐段單位爐溫對出鋼平均溫度及中心溫度的變化率?θm/?Ti及?θs/?Ti。還可確定最小燃耗函數P的各爐段加權系數Wi。
令各段在線爐溫調節量ΔTi=(Ti,max-Ti,o)-ΔT'i,這就能在線性規劃中用ΔT'i代替ΔTi作為未知量以滿足非負條件。這時目標函數Pmin=-sum (ΣWiT'i)。文中還附有一個說明各段爐溫按上述線性規劃進行最佳控制的例題。Abstract: By one-dimensional model, the flame jets are simulated as a flat flame layer lying between upper and lower exhaust gas layers. Then (he Hottel method of uni-dimensionat system is used to calculate the radiative transfer between these layers.
On the bases of Ricou-Spalding empirical formula for the free jet entrainment the mass transfer between the flame and its surrounding gas is calculated, then the mean temperature tf is determined according to the heat balance equation. The heat transfer in the billet described as one-dimensional heat conduction problem is solved by using the finite difference method.
A simplified heat transfer simulation model is also developed for determination of the mean charge temperature or billet center temperature per unit grad of furnace temperature increment in each furnace zone as represented by ?θm/?Ti or ?θs/?Ti. The weight factors of the minimum fuel consumption function in different zones Wi are also obtained.
An example is given to show the optimal control of furnace zone temperature according to the above mentioned linear programming system. -

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