Article
Thermodynamics
Mohammed N. Asheruddin, Anand M. Shivapuji, Srinivasaiah Dasappa
Summary: This work presents experimental and numerical investigations on the conversion of biomass char in a thermal environment dominated by H2O. The study establishes that a temperature above 730°C is when char conversion becomes practically relevant, with a rate of 0.4 mg min-1 °C-1. The mass loss rate of char particles with different sizes is studied under various temperatures, H2O concentrations, and their combinations, showing that increasing temperature and reactant concentration reduces conversion time scales. The presence of H2 is found to inhibit the char-steam reaction, and the CO+H2O reaction plays a pivotal role in controlling char conversion.
Article
Energy & Fuels
Shengyu Zhou, Zhongjie Shen, Jianliang Xu, Zhenghua Dai, Haifeng Liu
Summary: This study numerically investigates the effect of temperature gradient on the conversion characteristic and reaction-induced force of a single carbon particle during the gasification process. The results show that the temperature gradient leads to a difference in the conversion rate of the particle surface, resulting in a net reaction-induced force. Furthermore, the reaction-induced force increases linearly with the increase of temperature gradient and rapidly increases with the increase of ambient temperature around the particle.
Article
Thermodynamics
Zhutao Liu, Jin-Hui Zhan, Dengguo Lai, Minghui Zuo, Xiaoxing Liu
Summary: This study investigated the intrinsic characteristics of Naomaohu coal pyrolysis in a two-stage fixed-bed reactor. The results showed that different temperature chars had varying effects on pyrolysis volatiles, with temperature playing a major role in affecting the distribution of pyrolysates. Char was found to be beneficial for the content and quality of light oil in the low-temperature range, but had a negative impact on the yield and quality of oil in higher temperatures.
JOURNAL OF THERMAL ANALYSIS AND CALORIMETRY
(2021)
Article
Energy & Fuels
Meng Ma, Jiaofei Wang, Yonghui Bai, Peng Lv, Xudong Song, Weiguang Su, Lu Ding, Juntao Wei, Guangsuo Yu
Summary: Volatile-char interactions affect the chemical structure and reactivity of coal char, with O-containing functional groups playing an important role in char reactivity. The decrease in gasification reactivity due to volatile-char interactions is attributed to the decrease in aromatic C-O and C=O, and the increase in graphite carbon structures.
Article
Energy & Fuels
Xiaoxiao Wang, Bimao Zhou, Shisen Xu, Gang Liu, Yibin Wang, Xiaohe Xiong, Houzhang Tan
Summary: A comprehensive char gasification model based on a random pore model with a correction factor eta is established in this study to depict the char conversion process for entrained-flow gasification. The model uses advanced correlations for char gasification process parameters, as well as a one-dimensional slag flow model coupled with a particle capture model to describe the deposition, flow and heat transfer process of the molten slag. The simulation results indicate that the comprehensive model has sufficient accuracy to model the multiphase reactions and slag flow characteristics of the gasifier. Additionally, the study investigates the effect of coal size on exit gas temperature, detailed char heterogeneous reactions, gasification performance and slag flow characteristics of the gasifier.
Article
Energy & Fuels
Zixin Jiao, Li Liu, Yan Zhao, Xiye Chen, Penghua Qiu
Summary: The study evaluated the cogasification reactivity of Shenmu bituminous coal (SM) char and corn straw (CS) char in CO2 and found that increasing the blend ratio of CS and gasification temperature can weaken inhibition and enhance synergy. The addition of CS volatiles, especially potassium (K), can promote the cogasification reaction, with the promotion effect increasing with temperature. The comparison between CS-SM blend char and CS char volatiles-SM char showed different effects on gasification reactivity depending on the presence of alkali and alkaline earth metals.
Article
Metallurgy & Metallurgical Engineering
Ya-jie Wang, Hai-bin Zuo, Jun Zhao, Guang-wei Wang
Summary: The study showed that the gasification reactivity of coal chars is influenced by coal rank and carbonaceous structure, with higher coal ranks leading to lower gasification reactivity and higher reaction orders.
JOURNAL OF IRON AND STEEL RESEARCH INTERNATIONAL
(2021)
Article
Agricultural Engineering
G. Grasa, I. Martinez, R. Murillo
Summary: Gasification kinetics of six chars from residual origin were studied under relatively low temperature, low CO2, and high H2O partial pressures. The Random Pore Model (RPM) showed the best fit to experimental results, but the selection of the reaction model depended on the ash composition, specifically the presence of alkali and alkaline earth metals. Chars with ash content higher than 30% wt. were modeled with the RPM model, while chars with the highest K/Si ratio required modified versions of the RPM to accurately predict reaction rates. Textural properties played a key role in determining reaction parameters, such as the pre-exponential factor and activation energy, for chars with similar ash content and composition.
BIOMASS & BIOENERGY
(2024)
Article
Green & Sustainable Science & Technology
Agnieszka Korus, Giulia Ravenni, Krzysztof Loska, Irena Korus, Abby Samson, Andrzej Szlek
Summary: Gasification char is an effective catalyst for tar reforming due to its abundance of surface active sites for heterogeneous conversion of hydrocarbons and interactions with reforming agents. The reactivity of char during gasification in CO2 is mainly influenced by metal content, while the conversion of toluene is strongly correlated with the surface area available for reactions.
Article
Thermodynamics
He Yang, Sarma Pisupati, Haoquan Hu
Summary: The study modified a previous model to predict the N2 adsorption specific surface area of high-volatile bituminous char and analyzed the relationship between char surface area change and particle swelling.
PROCEEDINGS OF THE COMBUSTION INSTITUTE
(2021)
Article
Chemistry, Multidisciplinary
Wenguang Li, Yanfeng Shen, Jiang Guo, Jiao Kong, Meijun Wang, Liping Chang
Summary: Long flame coal has a directional regulation effect on sulfur transformation, while the addition of GL reduces the CRI of coke and affects coke reactivity.
Article
Energy & Fuels
Mengjie Liu, Xiaoming Li, Xuetao Wang, Jin Bai, Lingxue Kong, Zongqing Bai, Jian Li, Huaizhu Li, Lili Xing, Wen Li
Summary: Comparing gasification characteristics obtained by different methods can provide a deeper understanding for predicting gasification behavior and optimizing gasifier. The study found that particle size affects reactivity and kinetics, with smaller particles showing higher reactivity closer to intrinsic reactivity. The analysis also revealed that bed diffusion effects were significant in TGA but eliminated in HTSM.
Article
Thermodynamics
Xinsha Zhang, Meng Ma, Yonghui Bai, Weiguang Su, Xudong Song, Peng Lv, Jiaofei Wang, Guangsuo Yu
Summary: This study discusses the possibility of using torrefaction under CO2 as a pretreatment for industrial solid waste sludge, improving its gasification performance. The results showed that the torrefaction under CO2 can significantly enhance the gasification performance of the sludge.
THERMOCHIMICA ACTA
(2022)
Review
Engineering, Chemical
Fei Dai, Shengping Zhang, Yuanpei Luo, Ke Wang, Yanrong Liu, Xiaoyan Ji
Summary: Coal gasification is a core technology for clean coal utilization, enabling hydrogen-rich syngas production and reducing CO2 emissions. This review provides a brief overview of various coal gasification techniques, including conventional (fixed bed, fluidized bed, and entrained bed) and new (supercritical water, plasma, chemical-looping, and decoupling) gasification methods, discussing their gasifiers, process parameters, advantages, and challenges. Moreover, the potential of hydrogen production through different coal gasification technologies is analyzed. The decoupling gasification technology based on pyrolysis, coal char-CO2 gasification, and CO shift reaction is highlighted for its comprehensive coal utilization, low-energy CO2 capture and conversion, and efficient hydrogen production. This review also presents recent research advances in coal char-CO2 gasification, evaluating the influence of factors such as coal type, gasification agent composition, temperature, pressure, particle size, and catalyst on the gasification performance.
Article
Energy & Fuels
Chen Liang, Xiaofang Wang, Qinggang Lyu
Summary: Using oxygen and steam as gasifying agent in a Circulating Fluidized Bed (CFB) preheater can enhance the gasification reactivity of coal; replacing air by O-2-steam in the gasifying agent and controlling the modification temperature and steam to coal ratio can improve the gasification reactivity of modified char; the gasification reactivity of modified char increases and then decreases with the highest value at a steam to coal ratio of 0.87.
