EVERY VITAL INDUSTRY IN AMERICA OWES AN ENORMOUS DEBT TO THE
INDUSTRIAL CHEMIST AND CHEMICAL ENGINEER
INTRODUCTION
Just as the arts of tanning and dyeing were practiced long before the scientific principles upon which they depend were known, so also the practice of chemical engineering preceded any analysis or exposition of the princi les upon which such practice is based. The unit operations of cgemical engineering have in some instances been developed to such an extent in individual industries that the operation is looked upon as a special one adapted to these conditions alone, and is, therefore, not frequently used by other industries. All important unit o erations have much in common, and, if the underlying principres upon which the rational design and operation of basic types of engineering equipment depend are understood, their successful adaptation to manufacturing processes becomes a matter of good management rather than of good fortune. In this book we have attempted to recall to the reader’s mind those principles of science upon which chemical engineering operations are based, and then to develop methods for applying these principles to the solution of such problems as present themselves in chemical engineering practice. We have selected for treatment basic operations common to all chemical industries, rather than details of specific processes, and so far as is now possible, the treatment is mathematically quantitative as well as qualitatively descriptive. We venture to hope that the book will stimulate engineers to design apparatus adapted for any particular purpose, rather than just t o build it and then to rely on arge scale experimentation with expensive changes in construction to effect efficient operation.
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MONG all the fields of chemical endeavor the expression of American talent is nowhere more striking than in the industrial application of our store of scientific knowledge. The countless natural riches of our nation have provided fertile soil indeed for the expression of those skills. The past 75 years reveal an astounding growth. Today, that growth has proliferated until virtually every major industry owes an important debt t o the industrial chemist and chemical engineer, and the chemical process industries have assumed the lead position on the American industrial scene. Accounts will be given of developments in many of the chemical process industries elsewhere in this historical series. However, the story is not complete without a description of the advances in basic technology, both engineering and chemical, that are the common denominator for many of the advances in a specific industry. This historical section is devoted to that broad theme. It also includes histories of several important chemical process industries that do not fall within the logical scope of the other sections of the 75-year review.
T.
H. CHILTON
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HE concept of unit operations date8 back scarcely half way in the 75 years’ history of the AMERICAN CHEMICAL SOCIETY. It was in 1915 that the late Arthur D. Little (11) introduced this conception, in a report to the Corporation of the Massachusetts Institute of Technology.
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W. A. Pardee
Any chemical process, on whatever scale conducted, may be resolved into a ooordinated series of what may be termed (tunit actions,” as pulverizing, mixing, heating, roasting, absorbing, cohdensing, lixiviating, precipitating, crystallizing, filtering, dissolving, electrolyzing, and so on. The number of these basic unit operations is not very large, and relatively few of them are involved in any particular process. The complexity of chemical results from the variety of conditions as to temperatWe,presswe, etc.,under which the unit actions must be carried and from the limitations as to materials outin different of construction and design of apparatusimposed by the hysical and chemical character of the reactingsubstances. An aiility to cope broadly with the demands of his profession can be attained only through the analysis of processes into the unit actions of which they are composed, and the close study of these basic unit actions as they are carried out on the commercial scale under the conditions imposed by practice.
Little did not clearly differentiate in his “unit actions” bctween “unit operations” and “unit processes.” Following the adoption of the first by Walker, Lewis, and McAdams, this term. “unit operations,” has come to represent the primarily physical treatment steps that make up a chemical manufacturing process. Following the adoption of the title “Unit Processes in Organic Synthesis” by Groggins (4), this term has come to imply the occurrence of a distinct chemical change, rather than a mere physical treatment. The unit operations concept formed the inspiration for the rcsearches that were reported in a memorable series of symposia held by the Division of Industrial and Engineering Chemistry in 1921 on drying (8); in 1922 on distillation (9);in 1924 on heat transfer ( 6 ) ; and in 1924, also, on absorption (14). Stine (17) stated in 1928: Perha s the characteristic which most differentiates the chemicarengineering of today from the earlier activities of those interested in this field is the quantitative treatment of these various unit operations, and it is this exact and quantitative treatment of these operations which constitutes the province of modern chemical There was, of course, chemical engineering before 1915, when the unit operations concept was formulated, There a chemical manufacturing industry before 1908, when the Division of Industrial and Engineering Chemistry was established (under the original name “Industrial Chemists and Chemical Engineers”), and the American Institute of Chemical Engineers was founded. There was a chemical industry, even in 1876 when the AMERICAN CHEMICAL SOCIETY was founded. But the concept of chemical engineering as a profession and as a body of science emerged
This concept found immediate acceptance a t M.I.T. It became the inspiration of a whole school of teaching and research, there and elsewhere. It formed the basis of the outline of a work on the principles of chemical engineering, developed over the course of several years as mimeographed notes, and finally as the text (18)bearing that title, with these historic words in the preface:
Coordinator: W. A. Pardee, Gulf Research and Development Co., Pittsburgh, Pa. T. H. Chilton, E. I. du Pont de Nemours & Co., Wilmington, Del. 295
