THE CHEMICAL WORLD THIS WEEK C & E N REPORTS:
Compressed Gas Association
Companies Urged to Combat Public's Antibusiness V i e w s Public relations consists of d o i n g the right things as w e l l as saying the right things N E W YORK.—Misunderstanding of business in this country and public hostility have grown to such an extent that American freedom and our standard or living are both threatened, it was stated at the annual meeting of the Compressed Gas Association here, Jan. 25 to 27. Winning favorable public opinion, said Harold Brayman, Du Font's public relations director, has become one or the most important problems facing American business. If it is not solved, business and the American people will be the losers, Mr. Bray man declared. No single company or program can hope to do the job alone, the speaker continued. It calls for carefully correlated efforts by all, and each company can be most effective with its own employees, customers, suppliers, stockholders, and the people who live in the company's plant towns. Or all groups, the employees rank first in importance because they are the most important witnesses, for or against, to the community and the nation. As to the contention that public relations begins at home, Air. Brayman said that public relations consists quite as much in doing the right things as in saying the right tilings. No public relations program can take the place of sound policies, in his view. Fluorine Compounds. The relation of certain properties in fluorine compounds to the number of fluorine atcms and their placement in the molecule was discussed by E. G. Young, Du Pont. Some of the important considerations are hydrolysis, corrosion, flammability, thermal stability, and toxicity. Almost without exception, it is the compounds having more than one atom of fluorine which are inert and stable under all these conditions. Boiling points, hence vapor pressures, of fluorine compounds are predictable by following rules, but freezing points are not. Commercially useful fluorine compounds are for the most part the inert representatives. In this connection, the speaker took up at some length the Freon gases employed in refrigeration and aerosols, of which Freon 12 ( dicblorodifluoroinethane ) was discussed in some detail as to chemical process, plant design, and quality of product. The entire range of the inert fluorines outlined by the speaker ranged from Freon 14, which boils at —199° F. to Teflon ( tetrafluoroethylene ) , the "noble plastic." The liquid fliiorocarbons were discussed as to chemical process, plant design, and
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quality of product. The solid representatives, Teflon, Kel-F, and Fluorotbene bring the series to a close. Energy of Compressed Gases. Determination of the maximum energy of compressed liquified gases, \V. R. Bohlman, Pressed Steel Tank Co., said that the maximum energy of such gases upon instantaneous release from a container may
be represented by a thermodynamic process in which the liquified gas neither gains nor loses heat during the process. The maximum energy is not available for useful or destructive work in most instances, but under ideal conditions the maximum may be approached. Vapor pressure is a good index of the hazard of a compressed gas, but maximum energy is dependent not only on the vapor pressure but upon other characteristics of the gas as well. For several gases within limited temperature and pressure ranges, an empirical formula has been developed which permits approximation, within reasonable tolerances, of the theoretical values of maximum energy. The formula may be considered for a standard after suitable experimental evidence has been accumulated to verify its accuracy and to establish tolerable limits of maximum energy.
C & E N REPORTS: Texas A & M Instrumentation Symposium
Instrumentation Engineers Ponder V a l u e of Complete Automation Human operator p a r t in process control
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COLLEGE STATION, TEX.—With the current annual production of industrial instruments of all kinds at $1.8 billion, twice thai at the end of World War II, and the increasing trend toward the goal of "pushbutton" plants, the question, "How automatic can w e get?" is of the $64 variety to engineers concerned with instrumentation in the process industries. Kcynoting the 8th annual instrumentation symposium sponsored by Texas A&M College's department of chemical engineering, H. F. Dever, Brown Instruments, attempted some crystal-gazing in this direction. Money spent for industrial control instruments has risen from a range of 1 to 3 % of total capital expenditures for plant equipment prior to World War II, to 7 to 89c since, and Mr. Dever sees a reasonable limit a t about 13%. In a time of increasing emphasis on electronic principles at the expense of pneumatic instruments, he pointed out the need for more attention to the safety of the electrical systems. His prediction of greater application of servomechanisms brought a plea from the floor that these not b e oversold—that their operational capabilities relative to the process industries are not yet sufficiently understood to make them generally applicable. Whether the purpose of increasing the extent of automatic operation in a plant is a reduction of labor force, or is to increase the productivity of the individual operator, aroused some difference of opinion. Opinions of several speakers indicated that reduction of force may b e the longterm result, but increased operator produc-
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tivity is immediate. Mr. Dever had said that one of the keys to the extension of "automation" will be the digital computer, hut that it will have to b e much smaller for control room use than the mechanical brains presently developed. Following the same line of thought, A. F. Sperry, Panellit, Inc., said that the practical limit is not imposed by instruments themselves, but by the sheer complexity and volume of information they must convert to usable information and then store away. It is therefore the last fraction of the process of complete automation, Mr. Sperry said, that is so complex and expensive that it seems quite clear that the human operator will play a very essential part in automatic control of large processes for a long time to come. He further noted that the chemical industry is at a disadvantage with regard to such operations as petroleum refineries. Complex instrumentation design is a very slow process and, while refineries have reasonably stable operations, chemical plant process changes are usually so rapid that completely automatic instrumentation might be absolete before it was finished. Automatic Scanning. Descrihing the use of automatic scanners in monitoring process variables, Mr. Sperry,said that the increased number of repetitive readings, and the ever-increasing demands o n the operator's judgment and speed of reaction, will make it more and more difficult *for him to rely on individual instruments. H e believes that the cost per point monitored can be eventually brought down s o that
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THE CHEMICAL WORLD THIS WEEK the scanner can compete with the ordinary system, even in systems below 100 points. Infrared analyzers to continuously moni tor and control plant streams are being successfully employed in refineries. A number of these analyzers installed in his company's plants were estimated by D . E. Berger of Phillips to be returning from several thousand to several hundred thou sand dollars per year, with corresponding payout times from a year to a few days. Ο ver centralization—Bad P s y c h o l o g y ? Looking at the instrumentation field from the psychological standpoint of both opera tor and instrument man, T. A. Mangelsdorf, the Texas Co., had asked earlier that de sign engineers keep the human element in mind o n such things as ease of installation and also on simple items such as ease of
filling ink reservoirs. His warning against overcentralization of control instruments, to the extent that the operator mistook t h e control room for the processing unit, w a s repeated in an illustration by R. L. Nichols of Magnolia Petroleum Co. As early as 1930 such complete instrumentation w a s installed on a cracking unit built in Louisi ana. When it was brought on stream it ran over 3 0 days without requiring any a d justment by any operator. After the test period, some of the instruments were d e liberately removed so that the operators had to manually adjust some controls a n d thus keep in closer touch with the process. Overdoing Graphic Panels. There is no argument about the advantage of t h e graphic or "flow sheet" control panel in the right places, but the warning was t h e
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same from several speakers—"Don't put one in w h e r e it is neither necessary nor economical just because it looks good; don't clutter it u p with unnecessary d e tails." Both Mr. Sperry and R. L. Nichols gave sufficient examples to show that many companies ignored their warnings. S h o p - M a d e D e v i c e s . O f particular in terest to t h e chemical industry were sev eral items from the "Instrument Engi neer's Notebook" of Porter Hart, D o w Chemical C o . Many chemical plants use condensate returned from various operat ing units as a large portion of their boiler feed water, and employ a conductivity re corder to detect contamination in this con densate. Chlorinated hydrocarbons which D o w makes may contaminate condensate at its plants; these are not only nonconduc tors, and therefore not detectable b y con ventional equipment, but also cause c o n siderable d a m a g e to t h e boilers. To remedy this situation D o w flash-evaporates a sample from the condensate return line in a quartz thermal cracking tube. Con densed vapors from this cracker then flow over the conductivity cell, with concentra tions as l o w as a few p.p.m. detected. Little h a s been done, Mr. Hart said, to control automatically continuous evapora tors for concentrating chemical solutions. D o w set u p a control system in which a pressure transmitter pneumatically set a temperature controller, b u t this did not re sult în a straight line record for a given concentration. By converting the pneumatic-set temperature controller to a standard recording receiving controller, feeding outputs from the pressure and temperature transmitters into an averaging relay and t h e feeding output from the relay into the receiver controller, a straight line record is obtained for a given concentration. This enables operators to determine easily whether the concentration ^of the evaporator effluent is correct and to change the evaporator operation to produce a different effluent concentration. Self-Cleaning E l e c t r o d e s . Antimony electrodes £or p H determinations have had a bad reputation in industry because t h e y must be c l e a n e d so often, and motor driven cleaners require considerable maintenance. Since t h e s e electrodes h a v e definite advantages o-ver glass electrodes in solutions containing no oxidizing or reducing agents, especially a t high p H levels, D o w has replaced almost all its motor driven cleaners with self-cleaning electrodes. As described b y Mr. Hart, t h e selfcleaning electrode is a n annular ring of antimony c l a m p e d b e t w e e n two machined disks of insulating material, forming a race in which a n ordinary glass marble can circulate. T b e sample inlet is tangential to the chamber so that the force of the liquid causes t h e marble to rub along the antimony surface. Chamber outlet is in the center through a plastic tee into which the potassium chloride reservoir for the reference electrode is inserted. Only a f e w feet of liqirid h e a d are necessary to furnish sufficient pressure to cause the marble to keep the surface of the electrode clean.
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