The ash deposition mechanism in boilers burning Zhundong coal with high contents of sodium and calcium: A study from ash evaporating to condensing

Wang, Xuebin and Xu, Zhaoxia and Wei, Bo and Zhang, Lan and Tan, Houzhang and Yang, Tao and Mikulčić, Hrvoje and Duić, Neven (2015) The ash deposition mechanism in boilers burning Zhundong coal with high contents of sodium and calcium: A study from ash evaporating to condensing. = The ash deposition mechanism in boilers burning Zhundong coal with high contents of sodium and calcium: A study from ash evaporating to condensing. Applied Thermal Engineering, 80. pp. 150-159. ISSN 1359-4311. Vrsta rada: ["eprint_fieldopt_article_type_article" not defined]. Kvartili JCR: Q1 (2015). Točan broj autora: 8.

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Abstract

The high contents of sodium and calcium in Zhundong coal induce severe slagging and ash deposition in boilers. In this study, the ash deposition mechanism was investigated based on the results obtained from a full-scale boiler (350 MW) burning Zhundong coal, and a fixed bed reactor used for ash evaporating-condensing. In the full-scale boiler, the condensing and depositing of sodium and calcium sulfates play an important role on ash depositing on convection heating surfaces. Sulfates start to significantly condense and deposit at the flue gas temperature of about 850 °C on the medium and high temperature reheater surfaces. Ash evaporating tests proved that, with the increasing in temperature from 400 °C to 1200 °C, the ash evaporating process is divided into three stages: 1) 400-800 °C, 80 of sodium, and 100 of chlorine are released; 2) 800-1000 °C, all the left sodium evaporates and sulfur starts to be released with the formation of partial aluminosilicates; 3) 1000-1200 °C, all the left sulfur is released through the decomposition of calcium sulfates and then calcium starts to evaporate, while silicon oxides disappear due to the formation of new complex silicates. Ash condensing tests further proved that, the sodium in Zhundong coal was released mainly in the forms of atom, oxide, and chloride, in which sodium chloride account for about 50. When the evaporating temperature increased higher than 1000 °C, partial alkali and alkaline earth metals were released as gaseous sulfates, and afterward condense and deposit on the heating surfaces. At last, a temperature-dependent ash deposition mechanism in Zhundong coal combustion was proposed. © 2015 Elsevier Ltd All rights reserved.

Item Type:	Article (["eprint_fieldopt_article_type_article" not defined])
Keywords (Croatian):	Boilers; Calcium; Chemical reactors; Chlorine compounds; Coal; Deposition; Deposits; Silicates; Silicon oxides; Sodium; Sulfur; Sulfur compounds; Ash deposition; Evaporating temperature; Fixed bed reactor; Flue gas temperatures; Full-scale boiler; Heating surfaces; High temperature; Temperature dependent; Coal combustion
Subjects:	TECHNICAL SCIENCE
Divisions:	500 Department of Energy, Power Engineering and Environment > 510 Power Engineering and Energy Management Chair
Indexed in Web of Science:	Yes
Indexed in Current Contents:	Yes
Quartiles:	Q1 (2015)
Date Deposited:	09 Apr 2015 08:48
Last Modified:	23 Mar 2017 14:35
URI:	http://repozitorij.fsb.hr/id/eprint/3503

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