Heating furnace

The furnace serves for heating crude oil from temperature 220 deg C to 360 deg C. The fuel is methane, with excess of air 10 %. The unit has been formally divided into burner, where only mixing of inlet streams takes place, combustion chamber, heat exchanger, and a fictitious node that represents cooling 

The result only supports the general statement made in Example 8 of the previous section. The loss of exergy by irreversible chemical reactions, such as combustion reactions, is enormous. The theoretical possibility of exploiting better the chemical energy of fuel in electrochemical cells is, of course, known for years only technologically, the problem has not been solved so far. 

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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). 

W. Trioks, Industrial Furnaces, Fuels, Furnace Types and Furnace Equipment—Their S election and Influence Upon Furnace Operation, 4th ed., Vol. II, John Wiley Sons, Inc., New York, 1967, 358 pp., emphasis placed on heating furnaces (fuel-fired and electric) rather than melting furnaces. 

Power Supplies and Controls. Induction heating furnace loads rarely can be connected directiy to the user s electric power distribution system. If the load is to operate at the supply frequency, a transformer is used to provide the proper load voltage as weU as isolation from the supply system. Adjustment of the load voltage can be achieved by means of a tapped transformer or by use of a solid-state switch. The low power factor of an induction load can be corrected by installing a capacitor bank in the primary or secondary circuit. 

Some induction heating furnaces must operate at frequencies higher than the supply frequency. Formerly, rotating motor alternator frequency converters were used. Now the avadabdity of high speed, high power sdicon controlled rectifiers for use in frequency converters has made rotary converters obsolete. Modem units operate at higher efficiency, cost less, require less factory space, and coordinate readdy with process controls (2). 

A special coil configuration is used to heat thin strips of metal that caimot be heated efficiently with a coil that encircles the load, as the strip thickness is small compared to the depth of penetration. The transverse flux induction coil is positioned on either side of a strip to produce a uniformly heated strip with good efficiency in a much smaller space than conventional radiant or convective strip heating furnaces (6). 

Fig. 13. (a) Convection currents around electrically heated furnace tube (b) furnace construction to minimise convection (78). 

Electric heat provided by a resistance or by an electric arc can be substituted for the burning of a fuel. Electric furnaces can be designed in a variety of shapes and are more versatile than fuel-heated furnaces. The furnace atmosphere can be controlled independently of the chemistry of the combustion... 

At first, batchwise horizontal retorts were used for smelting, and later continuous vertical retorts, both externally fired. Continuous, internally heated furnaces such as the electrothermic furnace followed, and the last important development was the Imperal Smelting blast furnace. 

The largest quantity of commercial pyrolytic graphite is produced in large, inductively heated furnaces in which natural gas at low pressure is used as the source of carbon. Deposition temperatures usually range from 1800 to 2000°C on a deposition substrate of fine-grain graphite. 

When used for ceramic heating, furnaces are called Idlus. Operations include drying, oxidation, c cination, and vitrification. These Idlus employ horizontal space burners with gaseous, hquid, or solid fuels. If product quahty is not injured, ceramic ware may be exposed to flame and combustion gases otherwise, muffle Idlus are employed. Dutch ovens are used frequently for heat generation. 

Indirect rotary calciner. This is a bare metal cyhnder surrounded on the outside by a fired or elec trally heated furnace. It is suitable for operation at medium temperatures up to the maximum which can be tolerated by the metal w of the cylinder, usuaUy 6.50 to 700 K for carbon steel and 800 to 1025 K for stainless steel. 

FIG. 27-53 Methods of firing direct-heated furnaces. (From Marks Standard Handbook for Mechanical Engineers, 9th ed., McGraw-Hill, New York, 1987. Reproduced with permission. )... 

Germanium [7440-56-4] M 72.6, m 937 , 925-975 , b 2700 , d 5.3. Copper contamination on the surface and in the bulk of single crystals of Ge can be removed by immersion in molten alkali cyanide under N2. The Ge was placed in dry cyanide powder in a graphite holder in a quartz or porcelain boat. The boat was then inserted into a heated furnace which, after a suitable time, was left to cool to room temperature. At 750°, a 1mm thickness requires about Imin, whereas 0.5cm needs about half hour. The boat was removed and the samples were taken out with plastic-coated tweezers, carefully rinsed in hot water and dried in air [Wang J Phys Chem 60 45 7956]. 

Semi-finished products are first heated in a re-heat furnace until they are red hot (around 1200 C). On all types of mill the semi-finished products go first to a roughing stand. A stand is a collection of steel rolls (or drums) on which pressure can be applied to squeeze the hot steel passing through them, and arranged so as to form the steel into the required shape. The roughing stand is the first part of the rolling mill. The large semi-finished product is often passed... 

Blech flasche, /. narrow-necked tin vessel, -ge-fass, n. tin (plate) vessel, -gluhofen, m. plate-heating furnace, -hsfen, m. tin can. 

Charcoal is used in electrically heated furnaces to smelt specialty metals such as ferrosilicon. It is a preferred household fuel in developing countries with adequate forest resources. In the United States 95 percent of charcoal use is for barbecuing, while in Japan and Europe charcoal use is split evenly between cooking and industrial needs. 

This legislation was formally adopted on 26 November 1988. It applies to plant for the production of energy (effectively, boiler plant and similar) and specifically excludes heating furnaces, drying plant, etc. The Directive applies to plant of thermal input 50 MW and over. If two or more separate plants are in close proximity such that... 

Muffle furnaces. An electrically heated furnace of muffle form should be available in every well-equipped laboratory. The maximum temperature should be about 1200 °C. If possible, a thermocouple and indicating pyrometer should be provided otherwise the ammeter in the circuit should be calibrated, and a chart constructed showing ammeter and corresponding temperature readings. Gas-heated muffle furnaces are marketed these may give temperatures up to about 1200 °C. 

Electrically Heated Furnace In Atomic Absorption In "Trace Substances In Environmental Health - V . (D. D. 

Sources emitting radiation characteristic of element of interest (hollow-cathode lamp). Flame or electrically heated furnace or carbon rod. Monochromator, photomultiplier, recorder. 

Inductively coupled plasma technique, silver analysis via, 22 651 Inductively heated furnaces, 12 739 Industrial activities, categories of, 25 917 Industrial alcohol, specifications for, 10 545 Industrial applications... 

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