Frequent maintenance and limited plant availability.Little or even negative net energy production when taking into account all energy inputs.Wet feed stock results in less syngas production and higher energy consumption.Operational costs are high relative to that of incineration.Large initial investment costs relative to that of alternatives, including landfill and incineration.Main disadvantages of plasma torch technologies for waste treatment are: Air emissions can be cleaner than landfills and similar to that of incinerators.Gasification with starved combustion and rapid quenching of syngas from elevated temperatures can avoid the production of dioxins and furans that are common to incinerators.Safe means to destroy both medical and many other hazardous wastes.Production of value-added products (metals) from slag.Processing of biomass waste into combustible syngas for electric power and heat or for synthesis into fuels or chemicals.Potential production of vitrified slag which could be used as construction material.Some processes are designed to recover fly ash, bottom ash, and most other particulates, for 95% or better diversion from landfills, and no harmful emissions of toxic waste.Preventing hazardous waste from reaching landfills.The main advantages of plasma torch technologies for waste treatment are: Some plasma gasification reactors operate at negative pressure, but most attempt to recover gaseous and/or solid resources. A portion of the syngas produced feeds on-site turbines, which power the plasma torches and thus support the feed system. Inert slag produced from some processes is granulated and can be used in construction. Metals resulting from plasma pyrolysis can be recovered from the slag and eventually sold as a commodity. However, dioxins are formed during cooling of the syngas. The high temperature and lack of oxygen prevents the formation of many toxic compounds such as furans, dioxins, nitrogen oxides, or sulfur dioxide in the flame itself. Inorganic compounds in the waste stream are not broken down but melted, which includes glass, ceramics, and various metals. Pure highly calorific synthesis gas consists predominantly of carbon monoxide (CO) and hydrogen (H 2). Steam is sometimes added into gasification processes to increase the generation of hydrogen ( steam reforming). This creates an efficient transfer of energy which enable sufficient breakdown of the materials. Shredding waste to small uniform particles before entering the main chamber is generally required. However, a benefit is that the slag itself is chemically inert and safe to handle (certain materials may affect the content of the gas produced, however ). Too much inorganic material such as metal and construction waste increases slag production, which in turn decreases syngas production. Pre-sorting to extract treatable material for the gasification provides consistency. ![]() Content and consistency of the waste directly impacts performance of a plasma facility. Feedstocks may also include biomedical waste and hazardous materials. The feedstock for plasma waste treatment is most often refuse-derived fuel, biomass waste, or both. Molecular dissociation using plasma is referred to as "plasma pyrolysis." Feedstocks The resulting elemental components are in a gaseous phase ( syngas). Complex molecules are separated into individual atoms. Only at these extreme conditions can molecular dissociation occur by breaking apart molecular bonds. The waste is heated, melted and finally vaporized. ![]() ![]() The temperature of the plasma reaction determines the structure of the plasma and forming gas. Pressurized inert gas is ionized passing through the plasma created by the arc. A strong electric current under high voltage passes between the two electrodes as an electric arc. The electrodes vary from copper or tungsten to hafnium or zirconium, along with various other alloys. Small plasma torches typically use an inert gas such as argon where larger torches require nitrogen. It is used commercially as a form of waste treatment, and has been tested for the gasification of refuse-derived fuel, biomass, industrial waste, hazardous waste, and solid hydrocarbons, such as coal, oil sands, petcoke and oil shale. A plasma torch powered by an electric arc is used to ionize gas and catalyze organic matter into syngas, with slag remaining as a byproduct. Plasma gasification is an extreme thermal process using plasma which converts organic matter into a syngas (synthesis gas) which is primarily made up of hydrogen and carbon monoxide. Thermal process converting organic matter into synthesis gas using a plasma torch Plasma Arc gasification Process type
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