Article
Energy & Fuels
Jianan Qi, Cuigang Fan, Songgeng Li
Summary: The impacts of temperature and oxygen concentration on char structure evolution during pyrolysis were revealed using Raman spectroscopy, X-ray photoelectron spectroscopy (XPS) and BET characterization techniques. Char prepared under oxygen atmosphere showed higher reactivity compared to that under inert (N2) atmosphere, with the presence of oxygen reducing char graphitization at high temperatures. The presence of oxygen in pyrolysis improved pore volume and specific surface area, with a critical oxygen concentration observed at high pyrolysis temperatures.
Article
Energy & Fuels
Jianan Qi, Chuigang Fan, Hao Wu, Songgeng Li
Summary: In this study, step pyrolysis was conducted in a laboratory-scale fixed bed reactor to prepare char, and various characterization techniques were used to investigate the evolution of char structure during step pyrolysis. The results showed that step pyrolysis can increase the char yield, produce chars with higher graphitization degree, and suppress the release of sulfur and nitrogen.
Article
Chemistry, Applied
Lin Li, Shuai Tong, Lunbo Duan, Changsui Zhao, Zhipeng Shi
Summary: By comparing chars produced under different atmospheres, it was found that the pore structure and specific surface area of chars are significantly affected by the gasification environment, while the presence of chemical groups has a minor impact on the chars. The best gasification reactivities were obtained on the chars produced under 50%CO2/50%N2 and 50%H2O/50%N2 atmospheres, largely influenced by the porosity of the chars.
FUEL PROCESSING TECHNOLOGY
(2021)
Article
Engineering, Environmental
Lei Pang, Yingjuan Shao, Wenqi Zhong, Hao Liu
Summary: Pressurized oxy-coal combustion has potential for high efficiency and low cost CO2 capture. Increased pressure and oxygen concentration reduce burnout time of char particles and improve their reactivity and temperature. A combustion model shows pressure's impact on char burnout time.
CHEMICAL ENGINEERING JOURNAL
(2021)
Article
Energy & Fuels
Yuan Xiao, Guoliang Song, Xueting Yang, Zengcai Ji, Chao Wang, Qinggang Lyu
Summary: The post-combustion technology is a promising de-NOx technology, but the impact of stoichiometry air ratio in the furnace on char characteristics and nitrogen conversion under reduction atmosphere is not fully understood yet. This study found that the best char reactivity and developed pore structure occurred when the lambda(CFB) was 0.85, leading to lower NOx conversion ratios for FB and FS fuels. This information is useful for the industrial application of post-combustion technology.
Article
Thermodynamics
Xin Li, Jijun Tian, Yiwen Ju, Yanpeng Chen
Summary: This study investigates the permeability variations of different types of coal under elevated pyrolysis temperatures and identifies the factors influencing these variations. The results show that the permeability of lignite and high volatile bituminous coal increases initially and then decreases, while the permeability of medium volatile bituminous coal decreases initially and then increases. The permeability is controlled by the pyrolysis reactive strength and differs among coals with different maturities. The permeability variation is influenced by the relative strength between positive factors (such as water and volatiles' discharge) and negative factors (such as blocking of penetration channels).
Article
Energy & Fuels
Xiao Li, Guozhang Chang, Laishun Yang, Cuiping Wang
Summary: Gasification is an effective method to utilize excess coke production capacity. The addition of lignite and Fe/red mud oxides was found to significantly improve coke reactivity and increase the volume content of syngas. Fe4RM6 oxides further enhanced carbon conversion and demonstrated good performance after multiple gasification cycles.
JOURNAL OF THE ENERGY INSTITUTE
(2021)
Article
Energy & Fuels
Xin Li, Zhimin Lu, Jinzheng Chen, Xiaoxuan Chen, Yuan Jiang, Jie Jian, Shunchun Yao
Summary: The study demonstrates that oxidative torrefaction (OT) affects the combustion process of wood spheres, increasing char yield and combustion time while forming a more cross-linked aromatic structure that hinders volatile release, resulting in denser and heavier char particles. The findings suggest that mass yield serves as a good indicator for both OT and traditional inert torrefaction processes.
Article
Chemistry, Multidisciplinary
Yang Geng, Jinfeng Bai, Yang Liu, Xiangyun Zhong, Chao Li, Yang Liu, Zhihua Zhang, Yaru Zhang
Summary: The experimental study focused on the thermochemical reaction characteristics of different concentrations of phenol water and gasification-coke at 1000 degrees C. Results showed that increasing phenol water concentration enhanced the reactivity of gasification-coke, leading to higher syngas yield and heating value, but also causing damage to the carbon structure of gasification-coke.
REACTION CHEMISTRY & ENGINEERING
(2021)
Article
Energy & Fuels
Qian Chen, Zhuoran Liu, Yi Luo, Chong Xiang, Haojie Zhen, Xingjun Wang, Guangsuo Yu, Xueli Chen, Haifeng Liu, Fuchen Wang
Summary: Gasification in molten salt provides a promising way for direct carbon fuel cells. This study examined the interactions between char particles, coal, coal ash, and molten salt during gasification in molten salt using visualization and surface analysis approaches. It was found that the presence of molten salt accelerated the gasification reaction and conversion of char particles, while the entry and diffusion of molten salt had a dissolving and pore-expanding effect on the char particles. Raman analysis showed that dissolved (broken) char particles were more reactive than undissolved (unbroken) char particles.
Article
Chemistry, Physical
Athanasios Lampropoulos, Georgios Varvoutis, Miguel A. Montes-Moran, J. Angel Menendez, Michalis Konsolakis, George E. Marnellos
Summary: The dry gasification process of solid fuels is a promising pathway for utilizing captured CO2 emissions. The study conducted comprehensive analysis and modeling for olive kernel and lignite coal chars gasification using pure CO2 as gasifying agent. The reactivity and kinetics of the gasification reactions were examined and correlated with the physicochemical properties of the chars. The activation energy values and gasification mechanism were also determined.
INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
(2023)
Article
Thermodynamics
Zhang Yandi, Yang Huan, Wang Bo, H. M. Shahzaib Khan, Duan Xiaoli, Liu Yinhe
Summary: In slag tapping furnaces, char particles undergo complex structural evolution before and after being captured by the liquid slag layer, affecting carbon conversion rate. Experimental study on bituminous char at ash melting temperature reveals that as temperature increases, the ash droplets on char surface increase in size and density, with the gasification-specific surface area slightly greater than combustion-specific area. The content of chloride decreases to 1% and Fe, K, Mg, and Na content decrease significantly during pyrolysis across the ash melting temperature zone. The diffraction intensity of oldhamite increases while that of quartz dramatically decreases, indicating carbon substrate reaction with minerals during evolution. The ignition and burnout temperatures of char increase and combustion stability decreases with higher pyrolysis temperature.
JOURNAL OF THERMAL SCIENCE
(2022)
Article
Chemistry, Multidisciplinary
Yingyue Teng, Xiaoting Bian, Yinmin Song, Bingzhi Wang, Na Li, Runxia He, Yunfei Wang, Quansheng Liu
Summary: This study investigated the effect of the iron component on the microcrystalline structure transformation properties of lignite during pyrolysis. The results showed that the iron component promoted the generation of CO2, CO, and H2 in the low-temperature stage and inhibited the formation of CO and H2 in the high-temperature stage. The iron component also inhibited the formation of CH4 throughout the pyrolysis process. Moreover, it restricted the spatial arrangement of aromatic rings and inhibited the formation of large aromatic rings (≥6 rings).
Article
Energy & Fuels
Wei Pan, Dezhen Chen, Song Hu, Dunxi Yu, Lijie Yin, Yuyan Hu
Summary: This study investigated the impact of municipal solid wastes pyrolysis char (MSWC) combustion on its ash melting. The presence of carbon was found to reduce the ash melting temperature by approximately 40 degrees C, but the combustion rate of MSWC was much faster than that of ash melting.
Article
Energy & Fuels
Wei Pan, Dezhen Chen, Song Hu, Dunxi Yu, Lijie Yin, Yuyan Hu
Summary: This research investigates the impact of municipal solid wastes pyrolysis char (MSWC) combustion on ash melting. Experimental results show that the presence of carbon reduces the ash melting temperature by approximately 40 degrees C. The combustion heat promotes ash melting, while the combustion rate of MSWC is faster than ash melting. Increasing the surrounding temperature and O-2 concentration in combustion air promotes both combustion and ash melting. Higher carbon content in MSWC only slightly improves ash melting. Smaller particle size accelerates carbon combustion but does not contribute to higher ash melting ratio.
