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1 Sources
Published in Saeed Sahebdelfar, Maryam Takht Ravanchi, Ashok Kumar Nadda, 1 Chemistry, 2022
Saeed Sahebdelfar, Maryam Takht Ravanchi, Ashok Kumar Nadda
Gasification is not a new concept. Converting coal to a combustible gas has been practiced commercially since the early 19th century (Ahmed et al., 2019). Commercially, coal gasification may be used for fuel gas production for power generation or syngas as a feed for chemical syntheses as the first step in indirect coal liquification or coal to chemicals.
Case Study #1
Published in Tony Giampaolo, Gas Turbine Handbook: Principles and Practice, 2020
Although the preponderance of recent domestic powerplant construction has been based on either simple or combined cycle natural gas fueled combustion turbines, coal-fired power plants are still a mainstay of power generation world-wide. The emissions produced by coal combustion have led to environmental concerns to the point where coal use for electricity generation has been threatened. Parallel to the installation of flue gas scrubbers in conventional coal-fired power plants, IGCC development is proceeding on innovative power plant concepts which are not only more acceptable from an environmental standpoint, but also feature higher efficiency. To apply combined cycle technology to power production from coal requires conversion of coal to a gaseous fuel via a coal gasification process. Coal gasification processes involves partial combustion of coal to provide energy for further conversion of the coal into a gaseous fuel primarily containing carbon monoxide, hydrogen and nitrogen.
The Hydrogen Economy
Published in Michael Frank Hordeski, Alternative Fuels—The Future of Hydrogen, 2020
Coal gasification offers a more efficient way to generate electric power than by conventional coal-burning power plants. In a conventional plant, heat from the coal furnaces is used to boil water, creating steam for a steam-turbine generator. In a gasification-based power plant, the hot, high-pressure coal gases from the gasifier turn a gas turbine. Hot exhaust from the gas turbine is then fed into a conventional steam turbine, producing a second source of power. This dual, or combined-cycle, arrangement of turbines is not possible with conventional coal combustion. It offers major improvements in power plant efficiencies.
Numerical simulation of solid-fluid-thermal coupling in the heating stage of in-situ injection of supercritical water for hydrogen production from coal
Published in Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 2023
Zixiang Zhang, Yangsheng Zhao, Zijun Feng
Supercritical water – water with temperature and pressure greater than its critical point: 374.3°C and 22.1 MPa (Rong et al. 2023), respectively – is used as a homogeneous, fast-char gasification agent with unique physical and chemical properties, such as high diffusivity and the absence of surface tension. Supercritical water gasification (SCWG) is an emerging conversion technology for the clean and efficient conversion of coal, biomass, and organic waste into hydrogen-rich gases. SCWG offers many advantages over other coal gasification technologies, such as higher gasification efficiency, higher hydrogen production, and lower emissions of carbon dioxide and oxides of nitrogen and sulfur (Chen et al. 2021). Zhang Yaning (Zhang et al. 2019) analyzed the main factors influencing SCWG for hydrogen production, including feedstock characteristics, concentration, gasification temperature, residence time, reaction catalysts, and reactor pressure. Hu Yulin (Hu et al. 2020) discussed the advantages and technical challenges of using supercritical water as a reaction medium and proposed future research directions in SCWG for hydrogen production. Liu, Shumin (Liu et al. 2023, 2023) tested the pore structure and fractal characteristics of coals under cold leaching with liquid nitrogen for different coal qualities such as anthracite, bituminous coal and lignite, and investigated the variation of BET specific surface area, BJH total pore and adsorption pore specific surface area with the number of cold leaching with liquid nitrogen.
Investigating Compatible Drying Technique for Safe Utilization of Thar Coal, Pakistan
Published in International Journal of Coal Preparation and Utilization, 2022
Syed Nasir Mehdi, Zahid Mahmood Khan, Hafiz Umar Farid, Sadiq Hussain
Xu et al. (2016) investigated power system integrating a lignite drying unit, in which the solar energy has been used to lead the drying process diminishing the moisture concentration in fuel. Coal gasification allows most of the contaminants to be detached before the coal enters the combustion chamber and it also allows much more efficient combustion (Xu et al. 2018). Currently, other researchers’ work concentrated on the moisture content and combustion efficiency (Liu et al. 2012; Jayarathna et al. 2018). The thermal efficiency can be defined as the ratio of the lowest and highest temperatures happening in the thermodynamic cycle, which means that the more extreme the temperatures, the higher is the thermal efficiency potentially achieved (Chou et al., 2015) In addition, the two-fluid model (TFM) has been widely used for combustion and gasification processes in fluidized bed (FBD) (Zeneli et al., 2017; Wang et al., 2018; Hu and Liu, 2019). Jayarathna et al. (2019) modified fluidized-bed geometry to improve classification efficiency. Xu et al. (2015) anticipated an improved low-temperature lignite pre-drying arrangement using steam exhaust combined in an air-cooled lignite-fired power plant. Xu et al. (2016) proposed a two-stage pre-drying system that uses extracted steam and boiler exhaust flue gas as the heat source.
Experimental study on pore structure and mechanical dehydration of coal gasification fine slag
Published in Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 2022
Wei Yu, Xuebin Wang, Lijun Liu, Zhaochen Shi, Lina Wang, ZIA Ur Rahman
Coal gasification is a prominent clean and efficient process in the modern coal chemical industry for energy production (Guo et al. 2021). Gasification fine slag (CGFS) is a type of waste that is generated during the coal gasification process (Miao et al. 2021). The fixed carbon content of CGFS is 37.31% and the calorific value on a dry basis is 3809 cal/g, indicating a high utilization value. However, due to the high water content (69.22%), the calorific value is only 790 cal/g as received basis, making direct combustion difficult. Because of the inert residual carbon content, the coal gasification slag is unsuitable for use as a building material, road construction, or backfilling project (Lü Dengpan et al. 2021). At present, the treatment method of gasification fine slag is mainly stacking and landfill, resulting in serious environmental pollution and loss of land resources. Furthermore, landfilling slag results in a huge energy loss due to the high percentage of unburned carbon. Therefore currently, it has become a bottleneck for the sustainable development of an efficient and clean coal gasification processes (Liu et al. 2019).