Fluohmic Lab Reactor Reaches 2300° C. Electrically heated, fluidized-bed reactor could lead to commercial units for such temperatures A laboratory version of the Fluohmic furnace, a fluidized-bed type reactor, has successfully operated at 2300° C. (4100° F.)—well above the previous limitation of 1500° C. The unit, developed at Shawinigan Chemical, Ltd., of Shawinigan, Que., could well be the forerunner of commercial units operating at this temperature. Commercial versions of the Fluohmic furnace are already in use at temperatures of about 1500° C. Shawinigan, for example, has a production unit turning out hydrogen cyanide by the vapor-phase reaction of ammonia with propane. At Sasolburg, South Africa, African Explosives and Chemical Industries, Ltd., is incorporating the technique in the manufacture of calcium cyanide. If a commercial unit operating at the higher temperature is developed, it could open the way for using the technique to make a number of other products. Reactions such as metal oxides and halogens to give metal halides; pyrolysis of acetic acid and acetone to give ketene; hydrocarbon cracking; and use of the electrofluid bed as a preheater for chemical reactants have been investigated. At present, Shawinigan is keeping the results secret, however. Lab Model. Shawinigan's J. Reid told of the development of the hightemperature laboratory furnace at the 14th Chemical Engineering Conference in Hamilton, Ont. Basically, in a Fluohmic furnace (the name is a Shawinigan trade name) heat is produced by passage of electric current between electrodes which are positioned in a bed of fluidized, conductive particles. Fluid petroleum coke particles, properly calcined, are particularly good reactor charge, since their spherical shape leads to good fluidization. Other forms of conductive carbon are also satisfactory, though not as good as fluid petroleum coke. The Fluohmic furnace used to reach the 2300° C. operating temperature is a 5-in.-diameter unit with a top-entering electrode which has an enlarged stub at one end. The other electrode enters from the bottom and connects directly to the graphite crucible, 68
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which is conical at the bottom and has cylindrical walls. The stub of the top electrode centers in the crucible about 1V 2 in. above the gas disperser. Since all the materials of the crucible are conductors, the crucible can be considered a part of the bottom electrode. As temperature increases, current increases. The coke bed, fluidized by a reactant gas or mixture, becomes the site of the chemical reaction. The types of chemical reactions which can be carried out in a Fluohmic
furnace are limited by the nature of the bed material. So far, only carbon has given satisfactory results. But at moderately high temperatures, even carbon becomes reactive with various gases, such as oxygen, water vapor, and carbon dioxide. Thus, if these gases are reactants, their reactions with carbon must also be considered. Fluohmic reactors have all the advantages and disadvantages of conventional fluidized beds. Fluidized beds exhibit high heat transfer and good temperature uniformity, but the technique is limited to reactions which require contact times of about one to 60 sec. Reactions which are favored by rapid heating and high temperatures, and which have high energy requirements, are best suited to the reactor.
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