Experimental investigation on NO emission of semi-coke under high temperature preheating combustion technology. (1st January 2021)

• Record Type: Journal Article
• Authors: Lv, Zhaomin; Xiong, Xiaohe; Yu, Shilin; Tan, Houzhang; Xiang, Baixiang; Huang, Jun; Peng, Jianghua; Li, Peng
• Is Part Of: Fuel. Volume 283(2021)
• Publication Date: 2021-01-01
• Subjects: Semi-coke -- NOx emission -- Combustion characteristic -- Air ratio; Fuel -- Periodicals; Coal -- Periodicals; Coal; Fuel; Periodicals; 662.6
• DOI: 10.1016/j.fuel.2020.119293
• Languages: English
• ISSNs: 0016-2361

Abstract

Highlights: Proposing a method of controlling NOx emissions and promote burnout from semi-coke combustion. Analyzing the effects of higher preheating temperature and combustion temperature on NO emissions. Higher preheating temperature helps substantial N2 to be generated in the preheating furnace. Char plays an important role in reducing NO when the combustion temperature is high under fuel-rich conditions. Abstract: Low temperature (<1000 °C) preheating combustion technique with low NO x emissions has been applied to semi-coke combustion and make a good success. However, the de-NO x potential of higher preheating temperature (>1000 °C) has not been reported. Aiming to acquire a lower NO x emission, the preheating combustion technique with a higher preheating temperature (>1000 °C) has been tested on a two-stage drop-tube furnace in this paper. This work mainly focused on the preheating temperature and the combustion temperature these two factors on the NO emission and burnout characteristic. Results showed that higher preheating temperature (>1000 °C) could further lower the NO emission and enhance the combustion efficiency due to the early conversion of char-N to N2 . The NO reduction percentage can reach as high as 74% as the preheating temperature increased to 1400 °C. Moreover, the NO reduction degree was more significant in the fuel-rich conditions (i.e., α < 1). Meanwhile, the higher preheating temperature is also conducive to burn out for the early ignition of semi-coke. The effects of combustion temperature on NO emission strongly depend on the stoichiometry parameters. In air-deficient conditions, the NO x emission decreased with increasing temperature, whereas in oxygen-rich conditions the opposite trend occurred. The critical excess air ratio in this paper is around 0.95.