ENGINEERING, DESIGN, AND PROCESS DEVELOPMENT
Unit Processes in Chemical Processin The 18th Annual Unit Processes Symposium presented before the Division of Industrial and Engineering Chemistry at the 124th Meeting, American Chemical Society, Chicago, Ill.
At
this the Eighteenth Annual Unit Process Sympcsium, it seems appropriate to review the objects that have been before those who have directed or participated in these
unit process symposia. In general, these participants have been professors of chemical engineering or chemical engineers working in industry with some very important additions from professors of chemistry who are interested in the applications of chemistry to industry. The Division of Industrial and Engineering Chemistry sponsors and encourages these symposia with emphasis on the chemical aspects of chemical engineering-processes pertaining to the manufacture of chemicals. P. H. Groggins used the name “unit processes” to distinguish the chemical units and to supplement the older term “unit operations” assigned to the physical changes b y A. D. Little. Division into these two units-i.e., chemical and physical-was done to bring together on the one hand like chemical changes and, on the other hand, similar physical changes in order to correlate data and scientific rules or eventually laws that could b e used for the development and calculation of processes involving these chemical and physical units. In making chemicals the manufacturing process i s an integrated whole from raw materials to the finished products. This integration is often expressed as a flow sheet. Another definition i s a coordinated sequence of unit physical operations and unit chemical processes. In actual practice, as a rule, no separation takes place between the physical change and the chemical change. For instance, in the large majority of processes where the chemical change is the basis thereof, heat i s evolved or absorbed, depending on whether the reaction i s exothermic or
SUSPENSION COPOLYMERIZATION OF VINYL CHLORIDE AND VINYL ACETATE
E. J. Emmer and S. G. Bankoff
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DIPHENYLMERCURY SYNTHESIS
R. T. McCutchan and
K. A.
Kobe.
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endothermic. Therefore, the unit process i s accompanied b y the unit operation of heat transfer. If a process i s a continuous one, the unit process i s accompanied b y fluid flow as the reactants are pumped through the reaction vessel; or if it is a batch operation, the unit process i s accompanied b y the unit operation of mixing. In considering most unit operations or unit processes this actual simultaneous occurrence must be recognized. There are a few exceptions in the manufacture of chemicals in which there i s not this simultaneous occurrence-for example, the processes for obtaining salts b y the simple evaporation of naturally occurring brines. No chemical change occurs, but a simple crystallization of the sodium chloride or potassium chloride or whatever chemical is dissolved in the brine takes place. Even here an extension of a chemical change might be brought in b y applying this chemical change to the association of the ions into the different salts as they are deposited when the solubility products are exceeded. There are other instances in which the chemical engineer practices the unit operation or physical change without any chemical transformation taking place. This is true when fuel oil, gas, or sulfuric acid is pumped from place to place, involving the unit operation of fluid flow, or when other raw material or finished chemicals are subjected to transportation or size separation. The actual work of the chemical engineer in industry i s to take the basic chemical reactions worked out in the laboratory b y the chemists and to apply them to industry in order to make a profit for his company. This i s also a good definition of a unit process. e
CATALYTIC OXIDATION OF AMMONIA e
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673
H. F. Johnstone, E. T. Schowalter ,
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Houvouras, and W, R, e
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W. G. Domask and K. A. Kobe
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NITRATION OF !&METHYLNAPHTHALENE
J. A. 672
Brink, Jr., and
R. Norris Shreve
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and D.
F. Othmer
PRODUCTION OF HEXAMETHYLENETETRAMINE
708 713
K. A. Kobe and H. M. Brennecke
INDUSTRIAL A N D ENGINEERING CHEMISTRY
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F. Meissner, E. Schwiedessen, and D. F. Othmer MONONITRATION OF m-XYLENE
694
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782
PRODUCTION OF NITROTOLUENES
F. Meissner, G. Wannschaff, 689
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J. E. Knap, E. W. Comings, and H. G.Drickamer G. B. Bachman and M. Pollack
680
PYROLYSIS OF OIL SHALE IN GAS COMBUSTION RETORT
M. W. Putman and R. J. Cameron
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ALKYLATION OF ISOBUTANE WITH PROPYLENE
695
VAPOR PHASE NITRATION ETHYLENE CHLOROHYDRIN SYNTHESIS
NBRRIS SHREW
7’118 724
728
Vol. 46,No. 4
