Experimental investigation on effect of external circulation system on preheating characteristics of pulverized coal

Kun Su, Ziqu Ouyang, Hongliang Ding, Wenyu Wang, Jinyang Zhang, Hongshuai Wang and Shujun Zhu

Energy, 2023, vol. 278, issue C

Abstract: To explore whether self-preheating combustion systems ran steadily after loop seal failed, we comparatively investigated the influence of primary air ratio (λp) and extra heat input ratio (Cehi) on self-preheating of pulverized coal preheated in a 30 kW self-preheating burner with or without an external circulation (EC) system. For temperature distribution, lack of EC system greatly raised the temperature in the middle-lower part of the riser, and this temperature was more than 150 °C higher than that with the EC system. Moreover, extra heat input extended this influence throughout the riser. As λp and Cehi increased, the temperature in different positions always rose. For coal gas component and fuel component release, lack of EC system improved fuel composition conversion rates but reduced combustible gas yields. These two indexes increased simultaneously as λp and Cehi elevated properly, and there was an optimal λp with the EC system. Lack of EC system was inconducive to reducing particle size, improving specific surface area, promoting micro-pore generation on the surface and reducing graphitization extent, meaning the macrostructure and microstructure tended to be deteriorated in this condition. Nevertheless, the microstructure in this condition may be improved with extra heat input, and was even better than that with the EC system. The macrostructure and microstructure were improved as λp and Cehi increased properly, and there was an optimal λp with the EC system. The combustion reactivity of coal char was mainly influenced by the macrostructure, followed by the microstructure. Hence, absence of EC system tended to deteriorate it, and it was improved as λp and Cehi increased properly.

Keywords: Self-preheating; External circulation system; Primary air ratio; Extra heat input ratio; Self-preheating characteristics (search for similar items in EconPapers)
Date: 2023
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (1)

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Persistent link: https://EconPapers.repec.org/RePEc:eee:energy:v:278:y:2023:i:c:s0360544223011751

DOI: 10.1016/j.energy.2023.127781

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