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<p>To achieve deep NO<sub><i>x</i></sub> control, we investigated a purification-combustion system consisting of devolatilizer, swirl burner and down-fired combustor, and explored the influences of primary and secondary air ratios (λ<sub>p</sub> and λ<sub>2</sub>) on two-stage modification, combustion and NO<sub><i>x</i></sub> emission of pulverized coal in a 30 kW purification-combustion experimental bench. In devolatilizer and swirl burner, the temperature in different positions increases with λ<sub>p</sub> and λ<sub>2</sub> rising. Moreover, the location of main burning zone in swirl burner could be changed by increasing λ<sub>p</sub> rather than λ<sub>2</sub>. CO and H<sub>2</sub> are the main burnable components in modified gases, and their concentrations decrease with λ<sub>p</sub> and λ<sub>2</sub> increasing. By contrast, the CH<sub>4</sub> concentration is extremely low. Purification system composed of devolatilizer and swirl burner outperformed single-stage devolatilizer in increasing specific surface area, pore volume, pore diameter and fuel conversion rate of pulverized coal as well as improving its carbon microcrystalline structure, and these indexes of modified char are better and better with λ<sub>p</sub> and λ<sub>2</sub> increasing properly in this system. In down-fired combustor, as λ<sub>p</sub> and λ<sub>2</sub> increase, the temperature changes slightly in reduction region, while it decreases in complete combustion region only at lower λ<sub>2</sub>. Properly rising λ<sub>p</sub> and λ<sub>2</sub> will reduce the NO<sub><i>x</i></sub> emission with high efficiency of above 99.00%, but the emission reduction driven by λ<sub>2</sub> is limited.</p>

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Experimental Study on Two-Stage Modification, Combustion and NOx Emission Characteristics of Pulverized Coal in a Purification-Combustion Reaction System

  • 期刊论文

  • 发表日期：

    2025年4月4日

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  • Kun Su,
  • Ziqu Ouyang,
  • Hongshuai Wang,
  • Yujie Hu,
  • Hongliang Ding,
  • Jinyang Zhang,
  • Shujun Zhu

摘要

To achieve deep NOx control, we investigated a purification-combustion system consisting of devolatilizer, swirl burner and down-fired combustor, and explored the influences of primary and secondary air ratios (λp and λ2) on two-stage modification, combustion and NOx emission of pulverized coal in a 30 kW purification-combustion experimental bench. In devolatilizer and swirl burner, the temperature in different positions increases with λp and λ2 rising. Moreover, the location of main burning zone in swirl burner could be changed by increasing λp rather than λ2. CO and H2 are the main burnable components in modified gases, and their concentrations decrease with λp and λ2 increasing. By contrast, the CH4 concentration is extremely low. Purification system composed of devolatilizer and swirl burner outperformed single-stage devolatilizer in increasing specific surface area, pore volume, pore diameter and fuel conversion rate of pulverized coal as well as improving its carbon microcrystalline structure, and these indexes of modified char are better and better with λp and λ2 increasing properly in this system. In down-fired combustor, as λp and λ2 increase, the temperature changes slightly in reduction region, while it decreases in complete combustion region only at lower λ2. Properly rising λp and λ2 will reduce the NOx emission with high efficiency of above 99.00%, but the emission reduction driven by λ2 is limited.