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Energy 35 (2010) 4102e4106

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Bituminous coal combustion in a full-scale start-up ignition burner: Influence of the excess air ratio
Chunlong Liu, Zhengqi Li*, Weiguang Kong, Yang Zhao, Zhichao Chen
School of Energy Science and Engineering, Harbin Institute of Technology, 92 West DazhiStreet, Harbin 150001, PR China

a r t i c l e i n f o
Article history: Received 4 December 2009 Received in revised form 16 June 2010 Accepted 19 June 2010 Available online 21 July 2010 Keywords: Start-up ignition burner Coal-burning utility boiler Excess air ratio Primary air velocity

a b s t r a c t
A start-up ignition burner has been proposed to reduce oil fuel consumption during the firing-upprocess and partial-load operation. To investigate the influence of different excess air ratios on bituminous coal combustion in the start-up ignition burner, full-scale reacting-flow experiments were performed for an experiment setup. The ignition burner was identical to that normally used in an 800 MWe utility boiler. Gas temperature distributions in the burner were obtained for excess air ratiosof 0.56, 0.75, 0.98 and 1.14 (corresponding to primary air velocities of 17, 23, 30 and 35 m/s). Coal burnout and the release of C and H were observed at the exit of the burner nozzle. Gases such as O2 and CO were measured at the center of the burner. A change in resistance was obtained within the burner. Ó 2010 Elsevier Ltd. All rights reserved.

1. Introduction An increase in efficiency andcontrol of pollutant emissions are the most significant utility boiler projects worldwide [1e5]. In firing-up a boiler, oil fuel is primarily used to pre-heat the combustion chamber of a furnace, bringing it to its operating temperature. Generally, oil fuel is delivered under high pressure by an oil gun with a delivery capacity of about 1 t/h. In the initial firingup of a bituminous coal-fired 300 MWeutility boiler, about 100 t of oil fuel is consumed. Concerns over increasing economic costs of pulverized-coal-fired power stations arising from oil fuel consumed in the firing-up process and partial-load operations has spurred interest in developing oil-free and start-up ignition burners. Various investigators have reported studies on oil-free ignition burners. Gorokhovski et al. [6] and Masaya etal. [7] studied the stabilization of pulverized-coal combustion using a plasmaassisted burner, while Kanilo et al. [8] investigated the ignition and combustion of pulverized coal using a microwave-assisted burner. In China, Zhang et al. [9] described their application of plasma ignition technology in bituminous coal-fired boilers. However, for such burners, two main problems arise: difficulties inextending the capacity of the burner and the frequent maintenance required during operation. Li et al. [10] investigated induction-heating ignition of a pulverized-coal stream. Induction-heating can supply

* Corresponding author. Tel.: þ86 4518648854; fax: þ86 45186412528. E-mail address: (Z. Li). 0360-5442/$ e see front matter Ó 2010 Elsevier Ltd. All rights reserved.doi:10.1016/

a reliable and convenient source of energy to ignite the pulverizedcoal stream, but this technology has not been previously reported to have been used in a utility boiler. A start-up ignition centrally fuel-rich burner (otherwise known as a tiny-oil ignition centrally fuel-rich burner) has been proposed (see Fig. 1) [11,12]. The burner features two oil guns arranged inthe central pipe and the firing-up are summarized as follows. Atomized oil from one oil gun, called the main oil gun, ignites and burns in a heat-insulated chamber. Subsequently, an oil flame ignites the atomized oil from the other oil gun, called the auxiliary oil gun. Cone separators are installed in the primary airecoal mixture duct to concentrate the pulverized coal into the central zone of the...
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