Industrial-scale investigations on effects of tertiary-air declination angle on combustion and steam temperature characteristics in a 350-MW supercritical down-fired boiler

doi:10.1007/s11708-020-0803-z

Front. Energy

2021, Vol. 15

Issue (1) : 132-142 https://doi.org/10.1007/s11708-020-0803-z

RESEARCH ARTICLE

Industrial-scale investigations on effects of tertiary-air declination angle on combustion and steam temperature characteristics in a 350-MW supercritical down-fired boiler

Xiaoguang LI¹, Lingyan ZENG¹(

), Hongye LIU¹, Yao LI², Yifu LI², Yunlong ZHAO³, Bo JIAO³, Minhang SONG¹, Shaofeng ZHANG¹, Zhichao CHEN¹, Zhengqi LI¹

¹. School of Energy Science and Engineering, Harbin Institute of Technology, Harbin 150001, China
². Guizhou Wanfeng Electric Power Co., Ltd., Xingyi 562400, China
³. Guizhou Xingyi Project Department, Huadian United (Beijing) Power Engineering Co., Ltd., Xingyi 562400, China

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Abstract

Industrial-scale experiments were conducted to study the effects of tertiary air declination angle (TDA) on the coal combustion and steam temperature characteristics in the first 350-MW supercritical down-fired boiler in China with the multiple-injection and multiple-staging combustion (MIMSC) technology at medium and high loads. The experimental results indicated that as the TDA increased from 0° to 15°, the overall gas temperature in the lower furnace rose and the symmetry of temperature field was enhanced. The ignition distance of the fuel-rich coal/air flow decreased. In near-burner region, the concentration of O₂ decreased while the concentrations of CO and NO increased. The concentration of NO decreased in near-tertiary-air region. The carbon in fly ash decreased significantly from 8.40% to 6.45% at a load of 260 MW. At a TDA of 15°, the ignition distances were the shortest (2.07 m and 1.73 m) at a load of 210 MW and 260 MW, respectively. The main and reheat steam temperatures were the highest (557.2°C and 559.4°C at a load of 210 MW, 558.4°C and 560.3°C at a load of 260 MW). The carbon in fly ash was the lowest (4.83%) at a load of 210 MW. On changing the TDA from 15° to 25°, the flame kernel was found to move downward and the main and reheat steam temperatures dropped obviously. The change of TDA has little effect on NO_x emissions(660–681 mg/m³ at 6% O₂). In comprehensive consideration of the pulverized coal combustion characteristics and the unit economic performance, an optimal TDA of 15° is recommended.

Keywords supercritical down-fired boiler industrial-scale experiment tertiary air declination angle coal combustion steam temperature

Corresponding Author(s): Lingyan ZENG

Online First Date: 26 March 2020 Issue Date: 19 March 2021

Cite this article:

Xiaoguang LI,Lingyan ZENG,Hongye LIU, et al. Industrial-scale investigations on effects of tertiary-air declination angle on combustion and steam temperature characteristics in a 350-MW supercritical down-fired boiler[J]. Front. Energy, 2021, 15(1): 132-142.

URL:

https://academic.hep.com.cn/fie/EN/10.1007/s11708-020-0803-z
https://academic.hep.com.cn/fie/EN/Y2021/V15/I1/132

Tab.1 Design and main operating parameters at different TDAs

Tab.2 Characteristics of coal

Fig.1 Combustion system of the down-fired 350 MW_e supercritical boiler with MIMSC technology/mm.

Fig.2 Locations of measuring points/mm.

Tab.3 Mean temperature of each floor of measuring ports

Fig.3 Gas temperature distributions in lower furnace/°C.

Fig.4 Heating process of fuel-rich coal/air flow.

Fig.5 Characteristics of front/rear water wall temperature.

Fig.6 Concentrations of gas species in the region near the wing wall of the inspection.

Fig.7 Experimental results of the parameters at the furnace exit.

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