Siemens furnaces

Open>hearth Furnace. A large rectangular furnace in which steel, covered with a layer of slag, is refined on a refractory hearth it is heated by gas or oil, and operates on the regenerative principle which was first applied to this type of furnace by Sir Wm. Siemens in 1867 (hence the earlier name siemens furnace). The type of refractory lining depends on the particular steelmaking process used see acid open-hearth FURNACE, basic OPEN-HEARTH FURNACE and all-basic FURNACE. The process is now obsolete. 

The first gas producer making low heat-value gas was built in 1832. (The product was a combustible carbon monoxide—hydrogen mixture containing ca 50 vol % nitrogen). The open-hearth or Siemens-Martin process, built in 1861 for pig iron refining, increased low heat-value gas use (see Iron). The use of producer gas as a fuel for heating furnaces continued to increase until the turn of the century when natural gas began to supplant manufactured fuel gas (see Furnaces, fuel-fired). 

The purification method that has become a near-standard is the Siemens process, where hydrogen reduces SiCl or SiHCl on the surface of a resistance-heated (to about 1150°C) high purity siUcon rod. The rod is usually U-shaped to reduce the height of the furnace. The result is a siUcon ingot several cm in diameter and >2 m long. It is tempting to write the siUcon tetrachloride—hydrogen reaction as... 

Electric-Arc Furnace. The electric-arc furnace is by far the most popular electric steelmaking furnace. The carbon arc was discovered by Sir Humphry Davy in 1800, but it had no practical appHcation in steelmaking until Sir William Siemens of open-hearth fame constmcted, operated, and patented furnaces operating on both direct- and indirect-arc principles in 1878. At that early date, the avadabiHty of electric power was limited and very expensive. Furthermore, carbon electrodes of the quaHty to carry sufficient current for steel melting had not been developed (see Furnaces, electric). 

Figure 10.4 shows a schematic representation of the multidimensional GC-IRMS System developed by Nitz et al. (27). The performance of this system is demonstrated with an application from the field of flavour analysis. A Siemens SiChromat 2-8 double-oven gas chromatograph equipped with two FIDs, a live-T switching device and two capillary columns was coupled on-line with a triple-collector (masses 44,45 and 46) isotope ratio mass spectrometer via a high efficiency combustion furnace. The column eluate could be directed either to FID3 or to the MS by means of a modified Deans switching system . 

Martin-. (Zron) Martin, open-hearth, -fluss-eisen, n. open-hearth iron, -fluss-stahl, m. open-hearth steel, -ofen, m. Martin furnace, open-hearth furnace, -ofenschlacke,/. open-hearth slag, -roheisen, n. open-hearth pig (iron). -Stahl, m. Martin steel (open-hearth steel). -stahlofeQ, m. open-hearth steel furnace. -verfahren, n. (Siemens-)Martin process, open-hearth process. 

The Siemens brothers (German) design the regenerative gas furnace. 

Jet tappers are used in tapping Siemens-Martin (open hearth) furnaces. They are hollow charges, which are insulated from heat by earthenware jackets when detonated, the tapping channel is produced. Other lance-shaped charges are used to break up blast furnace hangups. 

Siemens-Martin furnace-regenerator, 590 Sieve tray extractors, 483 capacity, 484,487 diameters, 483, 487 efliciency. 483.487 pulsed, 478,483,487 sizing example, 486 Sieve trays, 428 assembly in a tower, 428 comparison with other types, example, 431... 

Very high temperature operations such as those of production of glass or metals utilize single-hearth furnaces, often with heat regenerators for fuel economy. The Siemens-Martin furnace of Figure 17.30 (f) with a hearth 13 ft wide and 40 ft long has a production rate of lOtons/hr of steel with a residence time of... 

These combustion developments were first tested for steelmaking in 1863 in France, under license from Siemens, by a father and son team, E. Martin and P. Martin. Siemens himself tested the furnace for this purpose in Wales, 3 years later, and both operations were pronounced a success. These are now often referred to as the Siemens-Martin process after their joint development. 

The open hearth furnace uses the Siemens regenerative principle to raise maximum combustion temperatures to about 1,650°C and possesses a heating capability independent of the heat content or impurity burning reactions of the iron charge. These features enable the charge placed in the furnace to be any ratio of scrap to hot metal up to 100% scrap, since the furnace can melt this. Usual practice, however, is to use a roughly 50 50 mix of scrap to melt [17]. 

FIGURE 14.3 Operating details of an open hearth (Siemens-Martin) furnace for steel production. 

The next major improvement was the development of the Siemens or open hearth furnace. Unlike the Bessemer furnace, which relied solely upon the oxidation of various elements in the bath for heat, the open hearth furnace was fired by burners, which allowed for external fuel to add considerable melting power to the process. The most important aspect of the open hearth process was its use of preheated air. Without air preheating, the metal would have melted very slowly, if at all. The air preheating occurred in refractory brick checkers (or checker-work) located under... 

Cutaway view of a high temperature cell fit on a Siemens D 500 gonio meter. The image on the right (b) is a blow up of the sample chamber at the centre of the furnace shown on the left (a). ... 

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