CPFD modeling of hydrodynamics, combustion and NOx emissions in an industrial CFB boiler--颗粒学报PARTICUOLOGY

Chang, J., Ma, X., Wang, X., & Li, X. (2023). CPFD modeling of hydrodynamics, combustion and NOx emissions in an industrial CFB boiler. Particuology, 81, 174-188. https://doi.org/10.1016/j.partic.2022.12.019

CPFD modeling of hydrodynamics, combustion and NO_x emissions in an industrial CFB boiler

Jian Chang ^a *, Xinrui Ma ^a, Xin Wang ^a, Xiaohang Li ^b *

a School of Energy, Power and Mechanical Engineering, North China Electric Power University, Beijing, 102206, China
b Bluestar (Beijing) Chemical Machinery Co., Ltd, Beijing, 100176, China

10.1016/j.partic.2022.12.019

Volume 81, October 2023, Pages 174-188

Received 8 November 2022, Revised 15 December 2022, Accepted 29 December 2022, Available online 23 January 2023, Version of Record 3 February 2023.

E-mail: changjian@ncepu.edu.cn, lixiaohang@sinochem.com

Highlights

• A CPFD model is established to further tap the NOx abatement potential of CFB boilers.

• Oxygen-deficient combustion results in high CO and NOx contents in the bottom furnace.

• Intensifying/making full use of in-furnace reducing atmosphere helps to reduce NO emission.

• Appropriate reducing primary air and coal particle size favors for lower NOx emission.

Abstract

The ultra-low NOx emission requirement (50 mg/m³) brings great challenge to CFB boilers in China. To further tap the NOx abatement potential, full understanding the fundamentals behind CFB boilers is needed. To achieve this, a comprehensive CPFD model is established and verified; gas-solid flow, combustion, and NO_x emission behavior in an industrial CFB boiler are elaborated; influences of primary air volume and coal particle size on furnace performance are evaluated. Simulation results indicate that there exists a typical core-annular flow structure in the boiler furnace. Furnace temperature is highest in the bottom dense-phase zone (about 950 °C) and decreases gradually along the furnace height. Oxygen-deficient combustion results in high CO concentration and strong reducing atmosphere in the lower furnace. NO_x concentration gradually increases in the bottom furnace, reaches maximum at the elevation of secondary air inlet, and then decreases slightly in the upper furnace. Appropriate decreasing the primary air volume and coal particle size would increase the CO concentration and intensify the in-furnace reducing atmosphere, which favors for NO_x reduction and low NO_x emission from CFB boilers.

Graphical abstract

Keywords

Hydrodynamics; Combustion; NOx emission; CFB boiler; CPFD

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