Published 12 issues per year
ISSN Print: 1091-028X
ISSN Online: 1934-0508
Indexed in
EVOLVING PORE STRUCTURES OF LIGNITE DURING PYROLYSIS OBSERVED BY COMPUTED TOMOGRAPHY
ABSTRACT
Lignite is a low-rank coal with high moisture, low calorific value, and high volatiles content. To prevent spontaneous lignite combustion and to reduce long-distance transportation costs, we proposed an industrial solution for lignite dehydration modified qualitatively by in situ heat injection. We studied the evolution of lignite pore microstructures by microcomputed tomography up to 600°C. From room temperature to 600°C, pore-structure evolution of lignite occurred in three phases. At room temperature to 200°C (phase I), the numbers of pores and fissures and the specific surface area increased rapidly. At the end of this phase, the porosity increased to 37.9%, the percolation probability exceeded the percolation threshold of 31.17%, and seepage began. During phase II (200°C-500°C), pyrolysis increased the numbers of new pores and fissures significantly. The original and newly developed pores and fissures become interconnected to form larger pores and pore groups. The specific surface area and porosity increased slowly. During phase III, from 500°C to 600°C, the porosity increased rapidly to 47.8%. The ratio of the pore morphology along the long and short axis varied from 2.63 to 3.
-
Cai Ting-ting, Feng Zeng-chao, Zhou Dong, Multi-scale characteristics of coal structure by x-ray computed tomography (x-ray CT), scanning electron microscope (SEM) and mercury intrusion porosimetry (MIP), AIP Advances, 8, 2, 2018. Crossref
-
Wang Jianmei, Zhao Yangsheng, Mao Ruibiao, Impact of temperature and pressure on the characteristics of two-phase flow in coal, Fuel, 253, 2019. Crossref
-
Shi Xinghua, Pan Jienan, Pang Longlong, Wang Rui, Li Guofu, Tian Jijun, Wang Haichao, 3D microfracture network and seepage characteristics of low-volatility bituminous coal based on nano-CT, Journal of Natural Gas Science and Engineering, 83, 2020. Crossref
-
Zhang Liankun, Kang Tianhe, Kang Jianting, Zhang Xiaoyu, Zhang Bin, Chai Zhaoyun, Zhang Runxu, Wang Yuefang, Kang Guanxian, Zhao Guofei, Effect of Cyclical Microwave Modification on the Apparent Permeability of Anthracite: A Case Study of Methane Extraction in Sihe Mine, China, ACS Omega, 6, 23, 2021. Crossref
-
Wang Dengke, Zhang Ping, Wei Jianping, Yu Chong, The seepage properties and permeability enhancement mechanism in coal under temperature shocks during unloading confining pressures, Journal of Natural Gas Science and Engineering, 77, 2020. Crossref
-
Li Hongli , Li Yunbing , Zhang Qihang , Wang Xinyi , Wang Xin , Jin Pen , THE GAS AND SOLID PRODUCTS CHARACTERISTICS OF SEWAGE SLUDGE PYROLYSIS IN DIFFERENT TEMPERATURE RANGES , Journal of Porous Media, 25, 11, 2022. Crossref