Title: Numerical simulation and optimisation of CFB boiler furnace with air staged low NOx combustion

Authors: Shunsheng Xu; Donggang Yu; Fulian Yao; Kongyao Wang

Addresses: School of Mechanical Engineering, Xiangtan University, Xiangtan 411105, China; School of Energy Science and Engineering, Central South University, Changsha 410083, China ' School of Mechanical Engineering, Xiangtan University, Xiangtan 411105, China ' School of Mechanical Engineering, Xiangtan University, Xiangtan 411105, China ' School of Mechanical Engineering, Xiangtan University, Xiangtan 411105, China

Abstract: The decrease in pollution emission from circulating fluidised bed boilers is significantly meaningful for relieving the pressure of air pollution, especially in the situation of the improvement of national emission regulations. This study aims to reduce NOx emission by optimising the structure of the circulating fluidised bed boiler. A case study of a circulating fluidised bed boiler was conducted, and its whole air staged combustion model was simulated by FLUENT. The simulation results were verified by experiments adopted. This article investigates the effects of the ratio of primary to secondary air distribution, the ratio of upper to lower secondary air distribution, and secondary air incidence angle on NOx concentration at furnace outlet. The results show that applying air staged combustion technology in the circulating fluidised bed boiler and optimising the operation parameters are beneficial to reduce the NO concentration. Furthermore, under the conditions of optimal parameters, the NO concentration decreased from 142.97 mg/m³ to 108.22 mg/m³. This study provides analysis and theoretical guidance for reducing NOx concentration of circulating fluidised bed boilers.

Keywords: circulating fluidised bed; CFB; numerical simulation; grading combustion; low NOx combustion; ratio of primary and secondary air distribution; secondary air inlet angle; ratio of upper and lower secondary air; upper secondary air distribution.

DOI: 10.1504/PCFD.2022.127202

Progress in Computational Fluid Dynamics, An International Journal, 2022 Vol.22 No.6, pp.392 - 410

Received: 04 Jul 2021
Accepted: 06 Dec 2021
Published online: 28 Nov 2022 *

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