Reactors, chemical fired heater

FIG. 23-1 Heat transfer to stirred tank reactors, a) Jacket, (h) Internal coils, (c) Internal tubes, (d) External heat exchanger, (e) External reflux condenser. if) Fired heater. (Walas, Reaction Kinetics for Chemical Engineers, McGraw-Hill, 1959). 

Reactors, chemical, 567-582 classification, 568 ebbulating bed. 593 fermentacon, 654,659,660 fired heater, 574,575 fixed bed, 572 flame, 573... 

Fired heaters are available for providing heat transfer media of the types described in Section 13.2, including hot water, steam, mineral oils, silicon oils, chlorinated diphenyls (Dowtherm A), and molten (fused) salts. Fired heaters are also used as reactors, such as reformers in petroleum refineries and for pyrolysis of organic chemicals. Purchase costs for these specific types of fired heaters, based on heat duty, are presented in Table 16.32. 

A furnace, or fired heater, is a device used to heat up chemicals or chemical mixtures. Furnaces consist essentially of a battery of fluid-filled tubes that pass through a heated oven. These devices provide a critical function in the daily operation of the chemical processing industry. Process heaters are more technically defined as combustion devices designed to transfer convective and radiant heat energy to chemicals or chemical mixtures. These heaters are typically associated with reactors or distillation systems. Process heaters come in a wide variety of shapes and designs, but the basic styles include cabin, box, and cylindrical. The various parts of a process heater include a radiant section and burners, a bridgewall section, a convection section and shock bank, and a stack with damper control. Modern control instrumentation is used to maintain these rather large and elaborate systems. 

Fired furnaces are frequently used in chemical plants to provide energy at high temperatures. If a column, a reactor, or some other unit requires energy at a temperature level above that attainable by steam at reasonable pressure levels, a fired reboiler or heater is used. Steam in a chemical plant is seldom available for process use at pressures above 300 psia. The saturation temperature of 300 psia steam is 417°F. so if the column base temperature is above about 350°F, steam cannot be used. 

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