Online deposition measurement and slag bubble behavior in the reduction zone of pulverized coal staged combustion |
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Authors: | Denggao Chen Zhi Zhang Zhenshan Li Ningsheng Cai |
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Institution: | Key Laboratory for Thermal Science and Power Engineering of Ministry of Education, Department of Thermal Engineering, Tsinghua University, Beijing 100084, China |
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Abstract: | An online thermogravimetric measurement method of ash deposition was developed. Ash deposition and slag bubble in the reductive zone of pulverized coal staged combustion were investigated. Firstly, a steady pulverized coal staged combustion was achieved in an electrically heated down-fired furnace. Additionally, gas species, coal conversion, and particle size distribution were quantitatively measured. Secondly, real-time ash deposition rates at different temperatures (1100–1400 °C) were measured, and deposition samples were carefully collected with an N2 protection method. The morphologies of collected samples were investigated through a scanning electron microscope. It was found that the deposited ash transformed from a porous layer composed of loosely bound particles to a solid layer formed by molten slag. Different behaviors of the slag bubble were observed, and bubble sizes were significantly affected by the deposition temperature. A deposition and bubble formation mechanism was proposed and used for modeling. Results showed that the proposed model well predicted the observed ash deposition and bubble formation process. |
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Keywords: | Ash deposition Online deposition thermogravimetric measurement Slag bubble Staged combustion |
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