Page 461 - Academic Press Encyclopedia of Physical Science and Technology 3rd Chemical Engineering

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Encyclopedia of Physical Science and Technology EN014A-654 July 28, 2001 16:35

Reactors in Process Engineering

Gary L. Foutch
Arland H. Johannes
Oklahoma State University

I. Reactor Classifications
II. Primary Reactors
III. Generalized Reactor Design
IV. Special Reactor Configurations

GLOSSARY by the initial moles of reactant. Conversion is defined
only in terms of a reactant.
Adiabatic reactor Vessel that is well insulated to mini- Elementary reaction Reaction that has a rate equation
mize heat transfer and has an increase or decrease in that can be written directly from a knowledge of the
temperature from the initial inlet conditions due solely stoichiometry.
to the heats of reaction. Isothermal reactor Any type of chemical reactor oper-
Batch reactor Vessel used for chemical reaction that has ated at constant temperature.
no feed or effluent streams. The reactor is well stirred Mean residence time Average time molecules remain in
andusuallyruneitherisothermallyoradiabatically.The the reactor. Note that this is different from space time.
main design variable is how much time the reactants are Multiple reactions Series or parallel reactions that take
allowed to remain in the reactor to achieve the desired place simultaneously in a reactor. For example,
level of conversion. A + B → C and A + D → E are parallel reactions, and
Catalyst Substance that increases the rate of a chemical A + B → C + D → E + F are series reactions.
reaction without being consumed in the reaction. Plug flow reactor Sometimes called a piston flow or a
Continuous stirred tank reactor Sometimes called a perfect flow reactor. The plug flow reactor has contin-
continuous-flow stirred-tank reactor, ideal mixer, or uous input and output of material. The plug flow as-
mixed-flow reactor, all describing reactors with contin- sumption generally requires turbulent flow. No radial
uous input and output of material. The outlet concen- concentration gradients are assumed.
tration is assumed to be the same as the concentration Product distribution Fraction or percentage of products
at any point in the reactor. in the reactor effluent.
Conversion Fraction or percentage that describes the ex- Rate constant Constant that allows the proportional-
tent of a chemical reaction. Conversion is calculated by ity between rate and concentration to be written as
dividing the number of moles of a reactant that reacted a mathematical relationship. The rate constant is a

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