熱軋加熱爐爐氛低氧控制技術開發

A Control Technology for Minimizing Oxygen Concentration Inhot Rolling Reheating Furnace

10.30069/MM.201103.0002

鄭恆星(H. H. Cheng)；許元良(Y. L. Hsu)；廖啟民(C. M. Liao)；黃大松(T. S. Huang)

加熱爐 ； 低氧爐氛 ； 銹損 ； 氮氧化物排放 ； Reheating furnace ； Low-oxygen in furnaceatmosphere ； Scale loss ； Nitrogen oxides emission

鑛冶：中國鑛冶工程學會會刊

55卷1期（2011 / 03 / 01）

35 - 44

繁體中文

熱軋加熱爐利用燃料燃燒所產生之熱能來加熱鋼胚，是熱軋製程中能源消耗需求最大且碳排放量最大的製程，其中爐氛含氧量之高低對加熱爐燃燒效能，以及受熱體表面氧化銹層與燃燒反應氮氧化物（NOx）生成影響甚巨。爐內氧氣之來源有二，供給之燃燒空氣，以及鋼胚進出爐過程因爐門開啟所吸入之空氣，爐外冷空氣吸入也會影響鋼胚加熱均溫性。本研究提出一種具自調適特性之爐氛低氧控制技術，能依燃燒負載變動與控制迴路狀態變化，預估干擾因子對爐氛含氧量之影響，並自動調控爐壓與各爐區燃燒空氣供給量，使燃料充分燃燒並能減少燃燒廢氣剩餘氧氣，實現爐氛低氧控制。此控制技術已應用於中鋼公司第一與第二熱軋鋼帶工場，結果顯示冷空氣吸入所造成爐溫下降量大幅減少，以及穩定維持燃燒廢氣低氧狀態，同時經實際測試證實新控制技術能改善鋼胚均溫性，減少加熱爐能耗與鋼胚氧化銹損，以及降低燃燒廢氣NOx濃度。

In the reheating furnace of hot rolling mill, thermal energy from fuel combustion heats the slab via radiation and convection. Therefore, the furnace consumes most of the thermal energygenerated and produces lots of carbon dioxide in the hot rolling process. The oxygen concentration in the furnace atmosphere must be minimizedtocurtailfuel consumption, reduce scales on slab's surface, and lower nitrogen oxides concentration in the combustion gas. There are two sources of oxygen that affect the oxygen concentration in the furnace atmosphere. One is the combustion air supplied to the burner and the other is the outside air infiltrating into the furnace when the furnace door opened during hot rolling operation. In this study, a control technology was developed to inhibit the air infiltration and minimize the oxygen concentration in furnace atmosphere. The control technology applies a predictive methodthat estimates the state change in the control loop influencing combustion loading and automatically control the furnace pressure and combustion air. Theproposed controltechnologyhas been implementedin thereheating furnaces of No.1 and No.2 hot strip mill in China Steel Corporation. Results revealed that the control methodcan effectively inhibit the air infiltration when the furnace door is opened. The oxygen concentration in the furnace atmosphere isconsistently minimized after the implementation of the automatic control system.