Voz. 3, No. 4
VALUE OP INSPECTION TRIPS
405
THE VALUE OF INSPECTION TRIPS AS AN ADJUNCT IN THE TEACHING OF APPLIED CHEMICAL PRINCIPLES D. S. CHAMBERLIN, LEHIGH UNIVERSITY, BETHLEHEM, PA.,AND M. K. BUCKLEY, YALE NEWHAVEN, CONN. UNIVERSITY,
I n teaching the applied principles of any science, the best results can be obtained, not by a mere abstract consideration of them, but by concrete examples of their application and a visualization of their practical results. For this. reason, a course in technical or engineering chemistry cannot be considered as complete unless accompanied by plant inspection, which acts as a basis for thoughtful and fruitful discussion concerning the economic results obtained. For the most efficient instruction in such a course, the presentation of the basic principles of chemical engineering, the so-called unit processes, that is ( a ) transportation of solids, liquids, and gases, (b) crushing, grinding, and pulverizing, (c) sedimentation, elutriation, and flotation, ( d ) solution and crystallization, (e) evaporation and distillation, must be clearly and thoroughly enunciated before any one chemical manufacturing process is studied. When this fundamental material has been mastered, then specialization along given lines may be undertaken. The study of these unit processes should be presented with the aid of a well-planned laboratory course, lectures illustrated by reference to trade journals and catalogs, and supplemented by numerous problems dealing with installation, power requirements, upkeep, heat balance, etc., the end in view being the design, equipment, and installation of a small plant. A large and elaborately equipped workshop, fitted with demonstration size units of specialized apparatus is unnecesssry to teach such principles as filtration, sedimentation, distillation, crystallization, drying, etc. Equipment such as is found in any ordinary laboratory, manipulated with a little ingenuity, can be used to teach fractional crystallization; for instance, the production of barium nitrate from witherite, muriatic acid and Chili saltpeter; starch and corn sirnp from corn, etc. From results so obtained, the design for a small sized plant can be drawn. The interest of a student in the study of these principles can be sustained and strengthened by seeing some industrial process in operation, and his gram laboratory chemistry evolved into carload plant chemistry. For this purpose, inspection trips must be considered as a necessary requirement in the training of a technological chemist. For the best results t o accrue from an inspection trip, a plan of study of the plant and the procedure through the plant must be mapped ont with as much care as in the study of fundamentals. A tenet which to the authors appears self evident, is th.& inspectian trips should not be taken until the student i s prepard to arnd$rstand wkut he sees. It was found by them, however, that in several institutions
such trips were scheduled before the opening of the college term in order that the plants visited might be used as examples of definite type processes which were studied during the term and after such trips. Such a procedure cannot be of maximum benefit to the student; he will not have mastered the process in the plant and he will be unable to recall an operation which he did not understand. To obviate this, trips should be planned to occur a t mid-term or at other convenient times after the student has acquired a fair grasp of chemical engineering fundamentals. Fortunately, some of o w colleges are situated in rich chemical centers, allowing inspection trips of half-day and day periods. After a thorough ground work in a particular process, inspection of operations covering this group of chemical fundamentals may be made. With regard to colleges not so fortunate, trips can be extended to three days, covering a maximum of six inspections. If a plant employs a variety of processes, as in the case of a general chemical plant, a day may be very well spent on it alone. A continuous trip of more than three days is not advisable as the student becomes saturated with information and, in a good many cases, his physical stamina reaches so low an ebb that he is unable to get the best results from later inspections. The type of plant visited should be that which offers as wide an application of chemical principles and machineries as possible. The industry should be one in which the flow of materials can be easily traced and one in which the operation of machinery is visible. This necessitates a knowledge, on the part of the instructor, of the plant visited and he should have this particular plant in his mind's eye when he lectures on that subject. The student will then see unfolded before him the process as he has visualized it. I n order to get this particular viewpoint, the instructor should visit the plant prior to the trip. He should develop the trip through the plant in a manner that will make the inspection of the greatest value to the student. The instructor should not merely indicate a furnace and state that i t is a hearth furnace for the production of sulfur dioxide. He should give an idea of the furnace construction, capacity, method of heating and state whether it operates under oxidizing or reducing conditions, and how it is charged and discharged. Such elaborate discussion will bore some students, but it must be appreciated that inspection trips are for instruction and not for entertainment. In most instances, the time spent in inspection trips is rather limited so that the plants visited should be considered with the utmost care with regard to the diversity of operations. The plants should be small, compact, and above all things, modern. A plant using a large number of chemical engineering fundamentals in its processes, is admirable for inspection. With these points in view, the following industries will
VOL. 3, No. 4
V
m OF I N S P E ~ OTRIPS N
407
offer a wide choice from which an instructor can construct a well-balanced trip in almost any large industrial center. By-Produd Coke.-Illustrating transportation of gases, liquids, and solids: grinding, pulverizing, continuous retorting, candensing, crystallization, and distillation. Cement.-Quarrying, conveying, grinding, pulverizing, continuous retorting, waste heat recovery, mixing, and stirring. General Chnnicd Plant, Inorganic.-Acids, sulfuric (chamber and contact), hydrochloric, nitric, salts, and oxides. This comprises a study of tanks, stirrers, kneaders, mixers. hearth furnaces, nystallizatian, in situ, concentration, and solution. General Chnnicd Plant. Organic.-Manufacturing dyes and intermediates. This comprises a stndy of nitrators, sulfonators, autoclaves, drying. Nterpressing, volatile solvent recovery, distillation, and classiiication. Suear.-Clarifvin~. . . fiiterpressinp, vacuum evaporation, decalorizing, centrifuging. drying, and packing. Textiles.-Thread making, bleaching, printing, dyeing, and metal etching Added to the above list, the following industries give a partial insight into the applications of ehemical processes and machineries: rubber, leather, soap, paint, petroleum refining, varnishes, and fertilizers.
When studying a plant, a student should take special care to observe the source of raw material, whether close at hand or subject to long haulage, and the market for the finished product; in short, the reason for the location of the plant in a particular region. Within the plant itself, routing of material should be emphasized, and note made as to whether it is in a regular and orderly manner. The student should be taught to hunt for the reason of a particular scheme of movement. When dealing with the finished product, the student should have some idea as to the quantity of material produced in unit time as well as the cost per unit of product. This, of course, necessitates a knowledge of the percentage yield. A study of the plant itself should not be neglected. Such items as construction of plant, whether built for the purpose for which it is used or whether remodeled and adapted, are of prime importance in discussing the location of the different units of an operation and a flow-sheet of the material through them. Without doubt, the greatest benefits derived from inspection trips are the views presented in the report that should be required of the student. From a student's report, the instructor can get an insight into his tendencies, and will have a foundation on which to base recommendations as to his aptitude for plant production, executive work, or research along purely scientific lines. The phenomena are our data, and behind them we cannot go except in imagination.A. SCEUPSN~AUER
