T1合金沉積與煤／生質炭之混燒高溫腐蝕研究

High-temperature Corrosion of T1 Alloy under Co-firing of Coal / Biomass Charcoal Deposits

本研究旨在探討於溫度400℃至600℃，時間1至25小時環境下，T1鍋爐用合金鋼經沉積與煤／生質炭之混燒高溫腐蝕行為。經坩鍋混燒後進行金屬損失、XRD、OM及SEM/EDX分析試驗；結果顯示，合金與煤／生質炭之混燒氧化動力學均依循高溫氧化拋物線型定律，而隨著溫度及時間之增長，其金屬損失量亦隨之增加，其中以600℃之金屬損失量為最大；該合金沉積與煤／生質炭之混燒於600℃所產生之金屬損失量約為1.5~2倍的空氣氧化量。純燃燒生質炭所產生之金屬損失量約為0.75倍純燃燒煤的。再者，沉積與不同比例之煤／生質炭混燒比較，顯示生質燃料經炭化處理後之生質炭，其S、Cl等元素可有效去除，因此於燃燒過程所產生之氣氛、灰燼均較純煤中之S、Cl及K含量較低，T1合金鋼材於高溫時所受到之侵害相對較低，且其金屬損失量會也因生質炭添加比例增加而降低。沉積與煤／生質炭之不同比例混燒高溫腐蝕機制，開始階段因煤／生質炭倘未燃燒釋出S、Cl等元素，屬純高溫氧化行為；而隨著溫度及時間增加，所產生之S、Cl等元素與T1合金鋼產生硫化或氯化之破壞氧化皮膜（oxide scale）熱腐蝕行為。

The study of this paper is to discuss high-temperature corrosion behavior of T1 alloy under several different conditions. The mechanical properties of these welds after various heat treatments were studied and characterized using micro-hardness, tensile strength, TEM and energy dispersive x-ray spectrometer (EDS). Four tests, Metal loss, XRD, OM, and SEM/EDX, were applied to the processes. Experimental results show that both oxide kinetics of coal and biomass charcoal followed the parabolic law; the amount of metal loss increased with both time and temperature increase. The three factors of the test were varied. There were three temperatures: 600, 500 and 400 ℃; five time exposures: 25, 16, 9, 4, 1, hours. Finally, five different fuel mixtures were used: 0, 10, 20, 30 and 100 % of biomass charcoal balanced with black anthracite coal. The results show that a higher proportion of biomass charcoal in the fuel leaded to the less loss of metal. Therefore, T1 steels could suffer less damage from these elements of S、Cl at high temperature. As the result, the amount of metal loss would decrease with an increasing proportion of biomass charcoal.