Computational study on the effect of gasification reaction on pulverized coal MILD combustion diluted by N2 and CO2. (25th July 2019)

• Record Type: Journal Article
• Authors: Zhang, Zewu; Lu, Bowen; Zhang, Liqi; Li, Xiaoshan; Luo, Cong; Xu, Yongqing; Zhao, Zhenghong; Zheng, Chuguang
• Is Part Of: Applied thermal engineering. Volume 158(2019)
• Publication Date: 2019-07-25
• Subjects: Numerical simulations -- MILD combustion -- Gasification reaction -- Pulverized coal -- Combustion characteristics; Heat engineering -- Periodicals; Heating -- Equipment and supplies -- Periodicals; Periodicals; 621.40205
• DOI: 10.1016/j.applthermaleng.2019.113806
• Languages: English
• ISSNs: 1359-4311

Abstract

Highlights: The gasification reaction is remarkable under MILD combustion regime. Combustion characteristics affected by the gasification reaction is evaluated. Gasification reaction results in an ignition delay at O2 /CO2 and air cases. Gasification reaction shortens the char burnout time at air and O2 /CO2 cases. Char gasification reduces the NO emissions by inhibiting the NH3 conversion. Abstract: The behavior of pulverized coal gasification reaction under MILD combustion regime will be significant, and then it affects pulverized coal combustion. This work performs a computational study on the effects of gasification reaction on pulverized coal MILD combustion with N2 and CO2 dilution. Results show that, regardless of at air or O2 /CO2 atmospheres, the proportion of char consumed by gasification reaction exceeds 50%. The gasification reaction makes a decrease in flame temperature about 80 K at O2 /CO2 and about 50 K at air. The delayed ignition time affected by the gasification reaction is 1.38 ms at air while 3.29 ms at O2 /CO2 due the formation of CO. The presence of gasification reaction shortens the char burnout time at air and O2 /CO2 atmospheres. The reactions of H2 O and CO2 with char destroy the char surface structures and create additional porosity, which prompts the char burnout. The significant decrease in the NO x emission affected by gasification reaction at air and O2 /CO2 atmospheres can be attributed to the enhancement of NO reburning and the suppression of fuel-NO x conversion, i.e., NH3 + O2 → NO + products.