Effect of Co-firing Ammonia on Coal Volatile Flame Characteristics and Particulate Matter Formation Behaviours

doi:10.12096/j.2096-4528.pgt.22088

Abstract

Abstract:

Co-firing “zero-carbon, hydrogen rich, high nitrogen” ammonia (NH₃) fuel in coal-fired power plant is an important technical route to mitigate CO₂ emission. To explore the impacts of co-firing ammonia fuel on coal combustion and pollutant formation behaviour, the coal-ammonia co-firing experiments were carried out on a McKenna type flat-flame burner system. Combined with visible-light camera, flue gas analyser and thermophoresis probe sampling system, the influence of co-firing ammonia on the flame properties, gaseous pollutant and particulate matter formation was explored. The results show that the ammonia fuel ignites ahead of coal, and the additional heat released from ammonia combustion promotes the pyrolysis of coal and the release of volatile. Thereafter, it promotes the ignition and combustion of volatile, resulting in the increase of flame height and temperature. The added NH₃ is partially converted into NO in the volatile flame, resulting in a notable increase in NO concentration. Adding NH₃ improves the equivalent ratio of gaseous fuel, which promotes the conversion of volatile to soot, and finally increases the yield of soot particles.

Key words: coal-fired power plant, carbon emission, ammonia fuel, volatile flame, particulate matter, soot

CLC Number:

TK 16

Jingji ZHU, Yishu XU, Jingying XU, Huakun WANG, Xiaowei LIU, Dunxi YU, Jingjing MA, Minghou XU. Effect of Co-firing Ammonia on Coal Volatile Flame Characteristics and Particulate Matter Formation Behaviours[J]. Power Generation Technology, 2022, 43(6): 908-917.

Figures/Tables 12

Tab. 1 Proximate and ultimate analysis of coal

工业分析				元素分析
F_Cad	V_ad	A_ad	M_ad	C_ad	H_ad	N_ad	S_ad	O_ad
55.4	30.8	7.5	6.3	68.4	5.4	0.8	0.6	11.0

Fig. 1 Schematic diagram of combustion experimental system

Tab. 2 Parameter setting of premixed gaseous

参数	数值
过量空气系数	1.15
CO流量/(L/min)	1.17
CH₄流量/(L/min)	0.43
O₂流量/(L/min)	1.65
N₂流量/(L/min)	8.00
总流量/(L/min)	11.25

Tab. 3 Parameter setting of ammonia carrying

参数	无氨	低掺氨	高掺氨
NH₃体积分数/%	0	25	50
NH₃流量/(L/min)	0	0.05	0.10
N₂流量/(L/min)	0.20	0.10	0
Ar流量/(L/min)	0	0.05	0.10
总流量/(L/min)	0.20	0.20	0.20

Fig. 2 Volatile flame of coal at different time (1 s interval) before and after ammonia addition

Fig. 3 Ignition time, stability time of coal volatile and flame height before and after ammonia addition

Fig. 4 Temperature distribution along flame centerline

Fig. 5 Concentration distribution of O2，NH3 and NO in flame

Fig. 6 Concentration distribution of CO and CO2 in flame

Fig. 7 Morphology changes of soot on axis of coal-fired volatile flame before and after ammonia addition

Fig. 8 Number concentration of soot on axis of coal-fired volatile flame before and after ammonia addition

Fig. 9 Volume fraction of soot on axis of coal-fired volatile flame before and after ammonia addition

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