CG: n
CT: Gasification is a thermal conversion process, where carbonaceous material is converted into gaseous products under the influence of temperature and gasifying medium. In general gasification is carried out in the temperature range of 600°C–1000°C. The commonly employed gasifying agents are steam, air, CO2, and H2. The product gas is called either producer gas or syngas depending on its composition. The composition and yield of gasification product gas depends on several parameters, like raw material, reaction temperature, gasification medium, and gasification reactor system. At low temperatures, the gasification product gas mainly contains CO2, CO, H2, CH4, tar, N2, H2S, and several other hydrocarbons (Ren, Cao, Zhao, Yang, & Wei, 2019). This product gas is further processed downstream in order to remove the tar, CO2, and other impurities and to increase the concentration of CO and H2. However, for high-temperature gasification, the product gas already contains a higher amount of CO and H2. The gasification product gas with a high concentration of CO and H2 is commonly referred to as syngas. This syngas could be either combusted in engines to produce electrical energy or further converted into liquid fuels and/or chemical feedstock through Fischer–Tropsch synthesis. Syngas could also be converted into methane (synthetic natural gas) through a methanation process.
S: SDir – https://www.sciencedirect.com/topics/agricultural-and-biological-sciences/gasification (last access: 30 January 2024)
N: 1. From verb “gasify” (gas + –ify) and noun combining form “-fication” (Latin -fication-, -ficatio, from -ficare to make, from -ficus).
. The first known use of gasification was in 1812.
2. Technological process that can convert any carbonaceous (carbon-based) raw material such as coal into fuel gas, also known as synthesis gas (syngas for short). Gasification occurs in a gasifier, generally a high temperature/pressure vessel where oxygen (or air) and steam are directly contacted with the coal or other feed material causing a series of chemical reactions to occur that convert the feed to syngas and ash/slag (mineral residues).
3. While the goal of combustion is to produce the maximum amount of heat possible by oxidizing all the combustible material, the goal of gasification is to convert most of the combustible solids into combustible gases such as carbon monoxide, hydrogen, and methane.
4. Gasification reactions. During gasification, coal initially undergoes devolatilization, and the residual char undergoes some or all of the reactions listed in the Table. The table also shows qualitatively the thermodynamic, kinetic, and equilibrium considerations of the reactions. As indicated by the heats of reaction, the combustion reactions are exothermic (and fast), whereas some of the gasification reactions are endothermic (and slower). Usually, the heat required to induce the endothermic gasification reactions is provided by combustion or partial combustion of some of the coal. Gasification reactions are particularly sensitive to the temperature and pressure in the system. As is shown in the table, high temperature and low pressure are suitable for the formation of most of the gasification products, except methane; methane formation if favoured by low temperatures and high pressures.
- Typical raw materials used in gasification are coal, petroleum-based materials, and organic materials.
- The resulting gas will contain hydrogen, carbon monoxide and hydrocarbons with large amounts of nitrogen (if air is used as a feed instead of oxygen); the exact composite will depend on the temperature, pressure, time and presence of catalyst.
S: 1. MW – https://www.merriam-webster.com/dictionary/gasification, https://www.merriam-webster.com/dictionary/gasify, https://www.merriam-webster.com/dictionary/-fication (last access: 30 January 2024); Etymonline – https://www.etymonline.com/search?q=ification (last access: 30 January 2024). 2. NETL – https://netl.doe.gov/research/Coal/energy-systems/gasification/gasifipedia/intro-to-gasification (last access: 30 January 2024). 3&4. EncBrit – https://www.britannica.com/technology/coal-utilization/Gasification (last access: 30 January 2024). 5. TERMIUM PLUS – https://www.btb.termiumplus.gc.ca/tpv2alpha/alpha-eng.html?lang=eng&i=1&srchtxt=gasification&index=alt&codom2nd_wet=1#resultrecs (last access: 30 January 2024).
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CR: bagasse, biomass, carbon monoxide, combustion, gasifier, grey hydrogen, hopper, hybridization, lean gas, ligno-cellulosic biomass, wood energy.
