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Fuels
Published in Kenneth M. Bryden, Kenneth W. Ragland, Song-Charng Kong, Combustion Engineering, 2022
Kenneth M. Bryden, Kenneth W. Ragland, Song-Charng Kong
Some coals melt and become plastic when heated and give off tars, liquors, and gases, leaving a residue called coke. Coke is a strong, porous residue, consisting of carbon and mineral ash that is formed when the volatile constituents of bituminous coal are driven off by heat in the absence of or in a limited supply of air. Coals that do not melt also give off tars, liquors, and gases when heated and leave a residue of friable char instead of coke.
Fossil Energy Markets
Published in Anco S. Blazev, Global Energy Market Trends, 2021
Metallurgical coke is used as a fuel and as a reducing agent in smelting iron ore in a blast furnace. The result is pig iron, and is too rich in dissolved carbon, so it must be treated further to make steel. The coking coal is low in sulfur and phosphorus, so that they do not migrate into the metal to deteriorate its properties.
Innovative Technologies for Sludge Reuse
Published in Alice B. Outwater, Reuse of Sludge and Minor Wastewater Residuals, 2020
Melting furnaces generate high-temperature combustion gas. Waste heat is recovered from the combustion gas to be used as the heat source for the pretreatment and melting processes. The heat is normally recovered by waste boilers as steam. Because of the highly calorific content of the coke, electricity can be generated during cokebed melting with steam dynamos.
Effects of microscopic characteristics on post-reaction strength of coke
Published in International Journal of Coal Preparation and Utilization, 2022
Jun Zhang, Jiaxiong Lin, Rui Guo, Caixia Hou
Coke is a porous carbon material, with thermal properties that depend strongly on the pore structure (Andriopoulos et al. 2003). During the thermoplastic stage, coal releases a large amount of volatile matter that flows into the pores of the coal particles and dilates the coal (Oh, Peters, and Howard 2010), yielding porous cokes after solidification. The pore structure is typically described by various parameters including the porosity, mean pore size, and pore-wall thickness (Nyathi, Mastalerz, and Kruse 2013; Patrick, Sims, and Stacey 1982). The reaction rate of lumpy coke is determined by the competition between pore-wall solution loss and carbon dioxide diffusion in the pores. In addition, the carbon-dioxide diffusion behavior varies with the pore diameter of the coke (Kawakami et al. 2005). Therefore, the pore size determines the behavior of the coke solution loss (Zamalloa, Ma, and Utigard 1995). The pore-wall is destroyed by the solution loss reaction. The expansion and combination of the pores determine the post-reaction strength of the coke. Furthermore, the optical texture of the coke, a unique feature reflecting the ordering degree of crystalline carbon (Coin 1987; Duber et al. 2000), results from many physical and chemical transformations occurring during carbonization. The solution loss reactivity varies significantly with the optical texture (Piechaczek and Mianowski 2017). Therefore, the thermal properties of coke are determined by the synergy between the optical structure and the pore structure.
Development of a circulating fluidized bed partial gasification process for co-production of metallurgical semi-coke and syngas and its integration with power plant for electricity production
Published in International Journal of Coal Preparation and Utilization, 2022
Diyar Tokmurzin, Desmond Adair, Timur Dyussekhanov, Kalkaman Suleymenov, Boris Golman, Berik Aiymbetov
Economic growth and urbanization are increasing the demand for the expansion of energy and water supply, transportation, housing, and public facilities. This leads to a growing demand for steel and its alloys. World demand for steel has almost tripled since the 1970s (World steel Association, 2018), and the main driver of this trend is Asia, where steel production almost quadrupled between 1970 and 2017 (IEA 2017; World Coal Institute 2007). Currently coal, coke, and semi-coke are irreplaceable in the iron and steel industry. Conventionally, steel is produced in blast furnaces, where coke is used as a vital component that plays the role of a reducing agent and heat source, and, provides mechanical strength to burden and permeability to gas and liquid phases (Li et al. 2014a). Coke is made by heating coking coals in a coke oven in a reducing atmosphere. High prices for coking coals and their scarcity have led steelmaking companies to search for ways to reduce coke consumption, alternative raw materials, alternative steel smelting, and coke making processes. Recently developed commercial processes such as iron bath smelting (American Iron and Steel Institute 2010; Street et al. 1998), blast furnaces with coal injection (Tang et al. 2017), COREX/FINEX process (Menéndez, Álvarez, and Pis 1999; Tang et al. 2017), and ferroalloys production (Hasanbeigi, Arens, and Price 2014; Xu and Cang 2010) allow the fine fraction semi-coke to be substituted for coke as the reducing agent. Semi-coke is a coal char with high-fixed carbon and low volatile content produced from coal through pyrolytic devolatilization.
Metallurgical coke production with biomass additives. Part 1. A review of existing practices
Published in Canadian Metallurgical Quarterly, 2020
Andrii Koveria, Lina Kieush, Olena Svietkina, Yevhen Perkov
Coke is a source of fuel and reductant in some of the metallurgical processes. In a blast furnace, coke functions as a structural support material for other materials. The main consumer of coke is the blast furnace process, wherein certain requirements pertaining to the quality of coke must be satisfied. In order to meet these requirements, the production of coke necessitates the use raw materials with certain initial characteristics as per proximate and ultimate analyses, particle size, petrographic composition, and coking capacity. To ensure the optimal parameters of the blast furnace process and to reduce coke consumption, the coke must possess high mechanical strength (M40, M25, M10 – the percentage of material remaining +40 mm, +25 mm, and – 10 mm round hole after 100 revolutions, according to the Micum drum test [8]), relatively low reactivity index (CRI), and high strength after reaction (CSR) [9].