Furnace, typical electric

Conventional Sintering Equipment. Like drying furnaces, sintering furnaces (29,76,85) can be periodic or continuous in nature. Periodic kilns offer greater flexibiHty continuous tunnel kilns are more economical. Advanced ceramics are typically siatered in high purity, controUed atmosphere furnaces by electric resistance heating. Ceramic furnaces used to fire traditional ceramic ware are generally heated with inexpensive natural gas, oil, wood, or coal. 

The modem electric arc furnace typically makes 150 tonnes in each melt, which takes around 90 minutes. 

The Subpart O standards apply to units that treat or destroy hazardous waste and which meet the definition of an incinerator. An incinerator is any enclosed device that uses controlled flame combustion and does not meet the criteria for classification as a boiler, sludge dryer, carbon regeneration unit, or industrial furnace. Typical incinerators1 2 3 include rotary kilns, liquid injectors, fixed hearth units, and fluidized bed incinerators (Table 23.1). The definition of an incinerator also includes units that meet the definition of an infrared incinerator or plasma arc incinerator. An infrared incinerator is any enclosed device that uses electric-powered resistance as a source of heat and which is not listed as an industrial furnace. A plasma arc incinerator is any enclosed device that uses a high-intensity electrical discharge as a source of heat and which is not listed as an industrial furnace. 

The refractory tends to degrade much faster in these furnaces, resulting in very short furnace campaigns, typically less than 2 years. Most of these furnaces are less than 40 ton (361) of glass per day however, furnaces as large as 200 ton (1801) per day have been built.6 A typical electric melter is shown in Figure 7.2. 

Proper use of oxygen enrichment can deliver many of the benefits of electric boost while decreasing melting cost. Typically, electric boost reduction is accomplished by either undershot enrichment or supplemental oxy/fuel burners. Undershot is more common on side-port regenerative furnaces, where installation of burners... 

Because of its small size and portabiHty, the hot-wire anemometer is ideally suited to measure gas velocities either continuously or on a troubleshooting basis in systems where excess pressure drop cannot be tolerated. Furnaces, smokestacks, electrostatic precipitators, and air ducts are typical areas of appHcation. Its fast response to velocity or temperature fluctuations in the surrounding gas makes it particularly useful in studying the turbulence characteristics and rapidity of mixing in gas streams. The constant current mode of operation has a wide frequency response and relatively lower noise level, provided a sufficiently small wire can be used. Where a more mgged wire is required, the constant temperature mode is employed because of its insensitivity to sensor heat capacity. In Hquids, hot-film sensors are employed instead of wires. The sensor consists of a thin metallic film mounted on the surface of a thermally and electrically insulated probe. 

Induction furnaces utilize the phenomena of electromagnetic induction to produce an electric current in the load or workpiece. This current is a result of a varying magnetic field created by an alternating current in a cod that typically surrounds the workpiece. Power to heat the load results from the passage of the electric current through the resistance of the load. Physical contact between the electric system and the material to be heated is not essential and is usually avoided. Nonconducting materials cannot be heated directiy by induction fields. 

The slag is batch tapped into a receiving room where it is cooled and broken up for disposal. The metal buUion is tapped from the furnace periodically via a siphon into 2-t cast-iron molds. Typical buUion content from an electric furnace in wt % is Sb, 13—18 Sn, 1—2 As, 0.5—1 Cu, 0.3—0.4 and Ni, 0.05—0.1. The balance is lead. 

Depending on energy and raw material costs, the minimum economic carbon disulfide plant size is generaHy in the range of about 2000—5000 tons per year for an electric furnace process and 15,000—20,000 tons per year for a hydrocarbon-based process. A typical charcoal—sulfur facHity produces approximately 5000 tons per year. Hydrocarbon—sulfur plants tend be on the scale of 50,000—200,000 tons per year. It is estimated that 53 carbon disulfide plants existed throughout the world in 1991 as shown in Table 2. The production capacities of known hydrocarbon—sulfur based plants are Hsted in Table 3. The United States carbon disulfide capacity dropped sharply during 1991 when Akzo Chemicals closed down a 159,000 ton per year plant at Delaware City, Delaware (126). The United States carbon disulfide industry stiH accounts for about 12% of the total worldwide instaHed capacity. 

Out of the 900 million tons of coal produced in the United States for domestic purposes in 1992, about 34 million tons were used for coking [10]. The overw helmmg majority of coal is consumed by the electric utilities. Nevertheless, in 1990, the United States steel industry required about 23 million tons of coke which was produced by the byproduct recovery slot oven [15] For a typical blast furnace, this translates to 0 5 tons of coke per ton of iron metal. 

VGCFs have typical diameters of 100 nm - 100 pm with hollow cores [9]. Thus VGCFs are 10 - lO times thicker than CNTs. A preparation method for VGCFs was first developed by Endo [10,11] wbo decomposed benzene at 1150-1.300°C in an electric furnace in the presence of H2 (99.9% pure) as the carrier gas (see Fig. 1). Ultra-fine particles of Fe (ca. 10 nm diameter) or its compounds, such as Fe(N03)3 or ferrocene, were introduced into the chamber as a catalyst. 

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