TG-FTIR study on co-combustion of bituminous coal semicoke and lignite
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TG‑FTIR study on co‑combustion of bituminous coal semicoke and lignite Ruidong Zhao1 · Jianguang Qin1 · Tianju Chen1 · Jinhu Wu1 Received: 8 June 2020 / Accepted: 11 November 2020 © Akadémiai Kiadó, Budapest, Hungary 2020
Abstract The combustion behaviors and pollutants emission characteristics during co-combustion of bituminous coal semicoke and lignite were investigated by thermogravimetric analyzer coupled with Fourier transform infrared spectrometer (TG-FTIR). Results showed the addition of lignite could lower the ignition and burnout temperature and also enhance the comprehensive combustion performance of blends. High heating rate could improve the combustion intensity and corresponding combustion characteristic indexes. The activation energy analysis by distributed activation energy model (DAEM) and Ozawa–Flynn–Wall (OFW) methods at lignite blend ratio of 40% indicated its distribution was consistent with the combustion process of blends. An obvious activation energy jump occurred at conversion rate range of 0.4–0.55 due to the poor ignition performance of semicoke. The average activation energy obtained by DAEM and OFW methods was 101.69 kJ mol−1 and 109.12 kJ mol−1, respectively. With the increase of lignite blend ratios, CO and CO2 emission gradually decreased. Meanwhile, NO emission increased, while NO2 and S O2 emission ascended after an initial decline. Semicoke had certain suppression effect on NOx and SO2 emission. The minimum NO2 and SO2 emission was obtained at lignite blend ratio of 20%. Keywords Semicoke · Lignite · Co-combustion · TG-FTIR · Gaseous pollutants
Introduction Pyrolysis has become one of the most efficient and clean technologies to realize cascade utilization of low rank coal, especially in China [1]. Semicoke is the solid product of low-rank coal pyrolysis process, and it is generally used in the chemical and metallurgical industry. But compared with its rapidly increasing production, the semicoke consumption in traditional industry is relatively limited [2]. As a result, large amount of semicoke piles up which causes great damage to the land, water and air and also the waste of resources. Due to the high calorific value and low pollution elements content, semicoke can be used as high grade and clean fuel. However, the volatile content in semicoke is very low and may result in the difficulty of ignition and burnout * Ruidong Zhao [email protected] * Jinhu Wu [email protected] 1
Key Laboratory of Biofuels, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao 266101, China
[3]. Co-combustion with high volatile fuel is a feasible way to avoid these drawbacks [4]. In recent years, because of the gradual depletion and rising price of high-grade coal, lignite-fired power plants grow rapidly, especially near the lignite mines [5]. Lignite is one of the low rank coals and has high volatile content. Hence, co-combustion of semicoke with lignite can effectively improve the ignition and burnout performance of semicoke which is promisi
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