Chinese Journal of Chemical Engineering ›› 2020, Vol. 28 ›› Issue (11): 2890-2899.doi: 10.1016/j.cjche.2020.05.039

• Energy, Resources and Environmental Technology • Previous Articles     Next Articles

Numerical simulation on optimization of structure and operating parameters of a novel lean coal decoupling burner

Jing Wang, Ruiping Zhang, Fengling Yang, Fangqin Cheng   

  1. Institute of Resource and Environment Engineering, Shanxi University, State Environmental Protection Key Laboratory of Efficient Utilization Technology of Coal Waste Resources, Taiyuan 030006, China
  • Received:2020-02-07 Revised:2020-05-17 Online:2020-11-28 Published:2020-12-31
  • Contact: Fangqin Cheng
  • Supported by:
    This work was supported by National Natural Science Foundation of China—Shanxi coal based low carbon joint fund (U1610254), Shanxi Province Basic Applied Research Youth Fund (201801D221345), 2018 Xiangyuan County Solid Waste Comprehensive Utilization Science and Technology Projects (2018XYSDYY-14).

Abstract: Due to its low volatile characteristics of lean coal, it is difficult to catch fire and burn out. Therefore, high temperature is needed to maintain combustion efficiency, while, this leads to high nitrogen oxide emission. For power plant boilers burning lean coal, stable combustion with lower nitrogen oxide emission is a challenging task. This study applied the 3D numerical simulation on the analysis of a novel de-coupling burner for low-volatile coal and its structure and operation parameters optimization. Results indicate that although it was more difficult for lean coal decoupling burner to ignite lean coal than high volatile coal, the burner formed a stepwise ignition trend, which promoted the rapid ignition of lean coal. Comparison of three central partition plate structure shows that in terms of characteristics of the flow field distribution, rich and lean separation and combustion, the structure with an inclination of 0° showed good performance, with its rich-lean air ratio being 0.85 and concentration ratio being 22.94, and there was an apparent decoupling combustion characteristic. Finally, the structure of the selected burner was optimized for its operational conditions. The optimal operating parameters was determined as the primary air velocity of 24.9 m·s-1 and the mass flow rate of pulverized coal of 2.5 kg·s-1, in which the pyrolysis products were utilized as reductive agent more fully. Eventually, the nitrogen oxide was efficiently reduced to nitrogen, which emission concentration was 61.88% lower than that in the design condition.

Key words: Numerical simulation, Low-volatile coal, De-coupling combustion, Lean coal ignition, NOx reduction