کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
6593435 | 1423542 | 2018 | 10 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
The effects of particle size and reducing-to-oxidizing environment on coal stream ignition
ترجمه فارسی عنوان
اثرات اندازه ذرات و محیط کاهش اکسید کننده در احتراق ذغال سنگ
دانلود مقاله + سفارش ترجمه
دانلود مقاله ISI انگلیسی
رایگان برای ایرانیان
کلمات کلیدی
محیط کاهش دهنده اکسید کننده، زغال سنگ، همگن، آتش گرفتن، جریان زغال سنگ،
موضوعات مرتبط
مهندسی و علوم پایه
مهندسی شیمی
مهندسی شیمی (عمومی)
چکیده انگلیسی
Coal particles experience a transition from a reducing to oxidizing environment in the near-burner region of pulverized coal (pc) boilers. For the first time, we report a fundamental study of ignition of a coal-particle stream experiencing a flame environment that transitions from a reducing to an oxidizing environment (termed reducing-to-oxidizing environment). High-speed videography is used to observe the particles in situ, and scanning electron microscopy is used to characterize the sampled particles. The effects of particle size on ignition are presented for four size bins (63-74â¯Âµm, 75-89â¯Âµm, 90-124â¯Âµm and 125-149â¯Âµm) for PRB subbituminous coal at two nominal gas temperatures (1300â¯K and 1800â¯K). An oxidizing environment with 20% molar oxygen composition is used as base-case. In contradistinction to single particle studies where particles are reported to ignite heterogeneously at higher temperatures, this study shows that coal streams ignite homogeneously, irrespective of particle size, in the oxidizing environment. By changing nominal gas temperature from 1300â¯K to 1800â¯K, ignition time decreases, on average, by a factor of five for each of the particle size bins. For both gas temperatures, the trend in ignition delays as particle size changes is non-monotonic. However, at 1800â¯K nominal gas temperature, ignition delays are independent of particle size in the reducing-to-oxidizing environment and ignition delays are doubled on average when compared to those in the oxidizing environment. It is more noticeable at the lower gas temperature of 1300â¯K that homogeneous ignition of coal streams is oxygen-dependent below 90â¯Âµm particle size and temperature-dependent above 90â¯Âµm. In general, ignition delay is determined by volatile release rate (controlled by the particle temperature) and the local oxygen concentration. Micrographs of particles also confirm that ignition and char burnout times are longer in the reducing-to-oxidizing environments than those in the oxidizing environments.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Combustion and Flame - Volume 195, September 2018, Pages 282-291
Journal: Combustion and Flame - Volume 195, September 2018, Pages 282-291
نویسندگان
Adewale Adeosun, Zhenghang Xiao, Zhiwei Yang, Qiang Yao, Richard L. Axelbaum,