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A heat‐transfer model for tube fouling in the radiant section of once‐through steam generators
The Canadian Journal of Chemical Engineering ( IF 2.1 ) Pub Date : 2020-09-10 , DOI: 10.1002/cjce.23880
Steven D. Herman 1, 2 , Anil K. Mehrotra 1
Affiliation  

Once‐through steam generators (OTSGs) produce steam by recycling produced water in the steam‐assisted‐gravity‐drainage (SAGD) process for extracting Alberta's oil sands via in situ recovery of bitumen. The industry's specifications for water quality, steam quality, and water recycle ratio, as well as high temperature and pressure operations, lead to the fouling of OTSG tubes, which has important economic, safety, and environmental consequences. The roles and mechanisms of inorganic and organic impurities on tube fouling also complicate the study of heat transfer in OTSGs. Heat transfer in OTSGs involves radiation, convection, conduction, forced convection, and boiling. In this investigation on OTSG fouling, a steady‐state mathematical model was built in Microsoft Excel, incorporating industry design data, to demonstrate the impact of tube fouling on heat transfer and tube‐wall temperature. The model predictions indicate that tube fouling introduces a significant thermal resistance that not only decreases the rate of heat transfer but also causes an increase in the tube‐wall temperature such that it could exceed the safe operating limits of the tube material, leading to potential tube failures. Predictions are provided for the average tube‐wall temperature exceeding the recommended operating limit of 700 K over a range of foulant thermal conductivity (ie, 0.05‐2 W m−1 K−1) and foulant thickness (ie, 0.4‐11 mm corresponding to 0.1%‐30% of the tube radius).

中文翻译:

直流蒸汽发生器辐射段中管道结垢的传热模型

直通式蒸汽发生器(OTSG)通过在蒸汽辅助重力排水(SAGD)过程中回收产出水来回收蒸汽,从而通过现场回收沥青来提取艾伯塔省的油砂。水质,蒸汽质量和水循环比以及高温和高压操作的行业规范导致OTSG管结垢,这对经济,安全和环境产生重要影响。无机和有机杂质在管道结垢中的作用和机理也使OTSG中传热的研究复杂化。OTSG中的热传递涉及辐射,对流,传导,强制对流和沸腾。在对OTSG结垢的调查中,在Microsoft Excel中建立了稳态数学模型,并结合了行业设计数据,证明管子结垢对传热和管壁温度的影响。模型预测表明,管道结垢会引入显着的热阻,不仅会降低传热速率,还会导致管壁温度升高,从而可能超过管道材料的安全运行极限,从而导致潜在的管道失败给出了在结垢导热系数(即0.05-2 W m -1 K -1)和结垢厚度(即对应的0.4-11 mm)范围内,平均管壁温度超过建议的工作极限700 K的预测到管半径的0.1%-30%)。
更新日期:2020-09-10
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