熱風爐為鋼鐵產業中重要設施之一，在其高溫之操作條件下如何達到穩定且長壽的使用，為其設計之重點，並且其內部一般以膨脹縫之設計達到吸收熱膨脹並且緩衝熱應力之功用。本次研究針對熱風爐內之膨脹縫進行分析，以套裝軟體ANSYS對中國鋼鐵公司34號熱風爐進行數值模擬，並討論膨脹縫對於其熱應力之效應。
本次研究分為三個部分，第一部分以一維簡化模型對膨脹縫進行探討，結果指出膨脹縫之設計可有效減緩內側磚材與外側鐵殼之熱應力，在給定膨脹空間為自由膨脹之空氣時效果最為顯著，磚材環向應力可由 -18.26MPa減少為 -7.88MPa，降低57 %，而給定膨脹空間為隔熱棉(Rockwool)時則根據隔熱棉之楊氏模數有不同程度之減緩效果，隔熱棉之楊氏模數越大減緩應力之效果較小。第二部分對實際熱風爐進行熱應力模擬，其第一主軸應力最大值4.84 MPa位於蓄熱室爐頂下端；第三主軸應力最大值 -10.96MPa位於連接管連接蓄熱室拱頂處，鐵殼等效應力則於兩側拱頂轉折處較大，最大值為311 MPa，其內目前設計之膨脹縫皆可有效吸收爐襯熱膨脹。第三部分討論實際熱風爐在無設計膨脹縫與給定楊氏模數較小之隔熱棉下之差異，模擬結果除爐襯第一主軸應力無明顯變化趨勢外，爐襯第三主軸應力最大值由 -18.51MPa減少為 -5.61 MPa，降低70 %，鐵殼等效應力最大值由611 MPa減少為227 MPa，降低63 %，磚材雖耐壓程度較高但由於耐火泥(mortar)可吸收其拉應力，故整體而言設計膨脹縫可有效達到穩固結構之效果。

The research used the software package ANSYS to simulate #34 hot blast stoves in China Steel Inc., and analyzed the effect on thermal stress for expansion gap.
The study was divided into three parts. The first part was the analysis of expansion gap for one dimensional simplified model. The results revealed that expansion gap could effectively reduce the thermal stress, and the reduced value was the largest in case that the expansion gap was filled by air. The hoop stress on inner side of brick reduced 57 % from -18.26 MPa to -7.88 MPa. Whenever the expansion gap was filled by Rockwool, the larger the Young’s modules was, the less the reduced stress would be. The second part was thermal stress simulation of actual hot blast stove. For bricks, the maximum value of first principle stress was 4.84 MPa which was occurred on lower end of checker roof. The maximum value of third principle stress was -10.96 MPa which was occurred on the junction of connecting pipe and checker roof. Besides, the value of equivalent stress of steel shell was the largest on turning point of both roof, which was 311 MPa. The third part compared the difference between hot blast stove without expansion gap and with rockwool expansion gap. The results revealed that except the first principle stress, the others reduced significantly. The maximum value of the third principle stress of brick reduced 70% from -18.51 MPa to -5.61 MPa. The maximum value of the equivalent stress of steel shell reduced 63% from 611 MPa to 227 MPa. Although brick could afford higher compressive stress than tensile stress, mortar could absorb the tensile stress on brick. To sum up, the arrangement of expansion gap could effectively make the structure firm.

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