1. Investigation on the influence of sulfur and chlorine on the initial deposition/fouling characteristics of a high-alkali coal
- Author
-
Gang Chen, Yuan Changle, Qingyan Fang, Yu Shenghui, Ma Lun, Xu Hao, and Cheng Zhang
- Subjects
Flue gas ,Fouling ,business.industry ,020209 energy ,General Chemical Engineering ,Sodium ,Energy Engineering and Power Technology ,chemistry.chemical_element ,02 engineering and technology ,Alkali metal ,Sulfur ,Fuel Technology ,020401 chemical engineering ,chemistry ,Chemical engineering ,0202 electrical engineering, electronic engineering, information engineering ,Chlorine ,Coal ,0204 chemical engineering ,business ,Deposition (chemistry) - Abstract
Sodium, calcium, sulfur and chlorine in the flue gas of coal-fired boilers are the main cause of ash deposition/fouling in heat exchangers. However, there are still many debates on the mechanism of ash deposition/fouling due to the lack of direct micro evidence. This paper aims to clarify the initial deposition/fouling characteristics of a high-alkali coal by computer-controlled scanning electron microscopy (CC-SEM). The results demonstrate that temperature has an influence on the deposition/fouling compounds. The crystalline compounds in the samples at 900 °C were mainly CaSO4 and Ca2Al2SiO7, while the compounds in the samples at 500 °C were mainly NaCl. Sulfur had a significant adsorption effect on sodium and calcium at 900 °C, while chlorine had a significant adsorption effect on sodium at 500 °C. A 3-layer microstructure of deposition/fouling was found after the samples were stripped by molecular force. Additionally, deposition/fouling could be divided into three stages: the formation of sodium salt precursors, the growth of loose structural aluminosilicates and the adhesion of particulates on the surface. Sulfates, especially Na2SO4 and CaSO4 formed a precursor for the initial deposition/fouling of high-alkali coal.
- Published
- 2020