INDUSTRIAL
and
ENGINEERING
WALTER J. MURPHY, Editor
Pilot Plants
THE
rapid growth of the c'liemical engineering profession has been an outstanding d e v e l o p e n t of the past several ilecades, coinciding n-ith an equally prominent advance of the chemical process industries. Chemical engineering, off- p i n g of chemistry and mechanical engineering. non- contains elements of knodedge available from neither of the other tKo. K e use the term "chemical engineer'' and "chemical engineering" advisedly. However, many \Those training was w i c t l y chemical! and u-ho now consider themselves industrial chemists, have become highly proficient in the chemical engineering phases of their n-ork. Our comments apply \!-it11 equal validity to this latter group, Many facts have been learned about the mechanism of chemical reaction in industrial equipment. These im-estigabions fully justify classification as scientific work. They m i k e out into a field where phenomena that are of negligible significawe in laboratory investigations become of prime iniportance. Characteristic examples are the dissipation of exothermic heat from large masses of reacting material, time lags in control of process variables, and inherent variation in rate and intimacy of mixing. These variables make the process development' problem so complex that data usually are unnvailable for a sound theoretical solution. In such instances the chemical engineer must turn to wt'ual tests for his am&-ers. He takes the infant process from the laboratory and selects the combination of available aiid custom-designed equipment that lie considers the optimum embodiment for volume production. Seldom do equipment characteristics match process specifications well enough to assure immediate succe More often his original choice proves only a "first appro ation.'! Final development is achieved only after many weeks, months, or years or' exploring the complex secondary effects introduced by t'he engineering equipment. I n contrast to laboratory research, perfection of achievement in terms of efficiencies and recoveries is unusual. Ordinarily the chemical engineer must make the process work despite basic limitations in equipment and materials. (Perhaps this occupational requirement' accounts for t'he reported high aptitude of the chemical engineer for making a success of marriage!) The oft-quoted advice to "make your mistakes on a sniall scale and your money on a large scale" usually is heeded in a chemical engineering investigation. The reaction sequence is tested in equipment too small for industrial feasibility but constructed to reveal the characteristics of the process when an a compercial scale. I n some instances the novel elements n f a new process are confined to one 0;. two steps, and no integrated study is necessary. T h e r e the unknowns ertend throughout the process. n pilot plant is used
Pilot plant investigations beautifully epitomize the elenlents .in modern chenlicd technology that call for the chemical engineer's qualifications. Skill in employment of the pilot plant method can accelerate the process development, and avoid serious tieferts in the full scale plant. It is strange that so little has appeared in technical literature on the specific techniques employed in pilot plant investigations, for tEley are a popular and nitlely used tool of chenlical investigation. Substantial adrantages shoul(l result fronl more extensive accounts of pilot plant work. ISDrSTRI.\L 4 N D E S G I X E E R I S G CHEXISTIiY is intrOtlLlciIlg 3. new monthly feature in the present issue that ive hope will stimulate more of this desirable discussion. The editors believe that the subject calls for a factual tieatnlent if cumuhtive advantages are to be obtained. IT-e have chosen. &Ccordingly. the device of the "case history" as a method of presentation. Each month a description of a specific pilot plant study nil1 appear, with the principal emphasis deroted, not to the process, but to the plant as an erperimerltal tool of the process development engineer. Sovel solutions to special problems that arose during its operation will be described and the discussion will revolve around the part the pilot plant played in translating the laboratory findirigs into a technically feasible process. It, is intended that the entire series will beconie a useful reference source for such common problems in pilot plant work 3s are exemplified by sani- . pling, equipment capacity relations, chemical and operational control, and personnel assignments. We hope you Kill find it interesting and useful, and welcome your comments. Inauguration of the new feature is undertaken x i t h the frank intention of enlarging the area comnionly accept'ed as the base .for publication of applied chemical knowledge. K e invite chemical engineers who have conducted pilot $lt investigations and are interested in the feature to submit the account of their work. Our hope is that articles on pilot' plant technology soon Kill become as customary as the chemiea1 research and unit operation papers that have long been established on our pages. Publication in applied science is successful and equitable only as long as those I\-ho benefit from it recognize their, moral obligation to support it. The authors who have spent time, thought. and experience in preparing the first articles to appear in the pilot plant feature have demonstrated their faith in it's merits. Through their generosit,y in pioneering the feature, you n-ill have the opportunity to judge from act'ual examples how this information benefits your oxn work. I n the final analysis, your response will determine whether this new area of technical knon-ledge is to beciome a permanent addition to our accepted traditions of scientific publirntion. 933
