能源科學(xué)導(dǎo)論2-(編輯修改稿)
2025-08-28 15:21 本頁面
【文章內(nèi)容簡介】 e gasifier. A gasifier converts hydrocarbon feedstock into gaseous ponents by applying heat under pressure in the presence of steam. ? A gasifier differs from a bustor in that the amount of air or oxygen available inside the gasifier is carefully controlled so that only a relatively small portion of the fuel burns pletely. This partial oxidation process provides the heat. Rather than burning, most of the carboncontaining feedstock is chemically broken apart by the gasifier39。s heat and pressure, setting into motion chemical reactions that produce syngas. ? Syngas is primarily hydrogen, carbon monoxide and other gaseous constituents, the proportions of which can vary depending upon the conditions in the gasifier and the type of feedstock. ? Minerals in the fuel (., the rocks, dirt and other impurities which don39。t gasify like carbonbased constituents) separate and leave the bottom of the gasifier either as an inert glasslike slag or other marketable solid products. Only a small fracture of the mineral matter is blown out of the gasifier as fly ash and requires removal downstream. ? Sulfur impurities in the feedstock form hydrogen sulfide, from which sulfur is easily extracted, typically as elemental sulfur or sulfuric acid, both valuable byproducts. Nitrogen oxides, another potential pollutant, are not formed in the oxygendeficient (reducing) environment of the gasifier。 instead, ammonia is created by nitrogenhydrogen reactions. The ammonia can be easily stripped out of the gas stream. ? In integrated gasification binedcycle (IGCC) systems, the syngas is cleaned of its hydrogen sulfide, ammonia and particulate matter and is burned as fuel in a bustion turbine (much like natural gas is burned in a turbine). The bustion turbine drives an electric generator. Hot air from the bustion turbine is channeled back to the gasifier or the air separation unit, while exhaust heat from the bustion turbine is recovered and used to boil water, creating steam for a steam turbinegenerator. Integrated Gasification Combined Cycle (IGCC) Coal Gasification ? 30% less coal needed pared to normal operation ? As much as 99% of sulfur and other pollutants can be removed and processed into mercial products as chemicals and fertilizers – Emission control technology – SO2 ?Wet Scrubbing濕洗 – use limestone石灰石 to create gypsum石膏 which can be used to make concrete
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