燃油连续加热炉数学模型

本文包括:(1)炉膛内钢坯加热数学模型;(2)最佳炉温及最低燃耗在线模型。 采用一维模型,应用Hottel多层无限大气层间的辐射热交换计算方法,把各火焰射流的作用,当量地看作是夹在上下炉气层之间的一个火焰层。它的平均温度t_f可以根据Ricou-Spalding射流吸入经验公式,计算火焰和周围炉气间的质量交换,再按热平衡方程把t_f计算出来。钢坯内部传热按一维导热问题,用差分求解。 还建立了一个较简单的炉膛传热仿真模型,据此求出各炉段单位炉温对出钢平均温度及中心温度的变化率θ_m/Ti及θ_s/Ti。还可确定最小燃耗函数P的各炉段加权系数W_i。 令各段在线炉温调节量ΔTi=(T_(i,max)—T_(i,o))—ΔT_i′,这就能在线性规划中用ΔT_i′代替ΔTi作为未知量以满足非负条件。这时目标函数P_(min)=-sum (W_iT_i′)。文中还附有一个说明各段炉温按上述线性规划进行最佳控制的例题。

Mathematical Models of the Oil Fired Continuous Furnace

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 tt 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 . 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.