熱風爐之燃燒、流場與熱傳數值模擬分析

Abstract

本研究係以商業套裝模擬軟體FLUENT來模擬熱風爐操作之一系列運作過程，其中包括燃燒、切換和送風三個過程。燃燒部分使用finite-rate之燃燒模組，蓄熱磚部分使用多孔性介質來做近似。數值模擬所得之計算結果著重於廢氣出口與熱風出口溫度值。在參考案例中，廢氣出口與熱風出口溫度隨時間變化之趨勢在模擬與實驗中皆相同，且廢氣出口與熱風出口溫度之模擬與實驗值的均方根誤差(RMSE)分別為2.0 %及1.2 %。 針對燃氣熱值、燃氣流量以及過剩空氣比等參數對於熱風爐操作的影響做一系列之研究，結果顯示可選擇如下方案以節省操作成本，並可穩定進行熱風爐之運作: (1) 減少混合燃氣中COG之使用量30 %，過剩空氣比維持1.03 (2) 減少混合燃氣總流量5 %，過剩空氣比維持1.03。

This study applies a commercial package software FLUENT to simulate a series of hot-blast stove’s operation processes. The operation process consists of on-gas, stove-change and on-blast cycles. The finite-rate combustion model and porous media approximation are adopted here. The simulation results focus on the waste gas and hot blast temperatures. In the reference case, the trends of experimental and simulated temperatures of waste gas and hot blast varying with time are the same, and the RMSE of waste gas and hot blast temperature between simulation and experiment are 2.0 and 1.2 % respectively. From a series of parametric studies consisting of the heating value and volume flow rate of mixed fuel gas and the excess air ratio, the results indicated that it can use the following cases to reduce the cost of hot-blast stove’s operation: (1) The quantity of COG in mixed fuel gas decreases 30 %, and the excess air ratio maintains 1.03. (2) The volume flow rate of mixed fuel gas decreases 5 %, and the excess air ratio maintains 1.03.