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Chemical Engineering Fundamentals Review
Process Control and Automation by Theodore J. Williams, Monsanto Chemical Co., St. Louis, Mo.
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year 1960 marked the coming ot age of the automatic control field. Internationally the first congress of the International Federation of Automatic Control was held in Moscow, June 27 to July 7, 1960. Over 1100 delegates from 29 countries participated. and heard 284 reports presented. These, when collected together, constitute a superb report of all ramifications of the field of automatic control (22, 78). Butterworths Scientific Publications of London is publishing the official English language version of all the reports and expects to have its printing completed by early 1961. The next Congress is scheduled to be held in Zurich, Switzerland, probably in September 1963. In the United States, the first Joint Automatic Control Conference was held at the Massachusetts Institute of Technology, Cambridge, Mass., Sept. 7-9, 1960. Here, again. control systems theory was the main subject of the 58 studies presented. This is to be a n annual event, rhe next one being at the University of Colorado, Boulder, Colo.. June 28 to 30, 1961. Both meetings were disappointing in the number of reports presented on process control and process dynamics topics. I n fact, the Joint Automatic Control Conference (JACC) presentation consisted of only 12. I n the program of the International Federation for Automatic Control (IFAC), a large proportion of the work on process control topics was conccrned with computer control. Only a few studies related to control dynamics of chemical processing units. All signs point to a much better representation of chemical process control topics in future JACC and IFAC meetings because of the continually expanding interest of our university departments. To this end, a second Summer Conference on Systems Engineering Theory for College Teachers of Chemical Engineering was jointly presented by LVashington University and the Monsanto Chemical Co. in St. Louis, Mo., June 7 to 30, 1960, under the sponsorship of the National Science Foundation with the cooperation of the American Institute of Chemical Engineers and the Foundation for Instrumentation Education and Research (FIER). Plans are under way for the presentation of another of the summer programs in 1961. Slater (92) reviewed the
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c‘irrent control offerings in the universities, and Eckman (26) and Ragazzini (87) discussed the problems of educating the control engineer. Education in dynamic topics \vi11 also be aided by the series instituted in the ISA Journa! by Peter Balise on process dynamics laboratory experiments (5, 6.50, 99) and by the review of small analog computer demonstration problems by Williams and Lauher (706). Probably the most outstanding report or the IFAC Congress was one by Kobrinskii and others (62) describing the results of a series of experiments in which an artificial arm operated directly from signals from the severed nerve ends of a patient. LYhile this study does not relate directly to chemical process control, i t is included here to indicate the inarvelous possibilities which the future may hold as automation advances. S e w books of importance are those by Ahrendt and Savant ( 7 ) , Caldwell and others (77), D’Azzo and Houpis (24), and Lauer and others (67).
Computer Control Next to the two confeiences just described, the most important development was the disclosure of many of the details of four important computer control installations: that of Goodrich Chemical Co. on a vinyl chloride-acrylonitrile complex a t Calvert Citv, Ky. (60, 69) ; Monsanto Chemical Co.’s ammonia plant at Luling, La. (21, 2 8 ) ; the crude still automation instituted by Standard Oil Co. of Indiana (23); and the thermal cracking furnace study by Phillips Petroleum Co. (87). Disclosures on these and the other 16 control computers applied to process industry applications (70~7)cannot help but promote the development of this field. An excellent review of the literature of computer control has been presented by Grabbe (391, while Grohskoff f47), Hall (43), and Williams (705) presented the current procrssing industry view of control computer applications. Mathematics and mathematical model building are the key to past and future appiications of these machines, as brought out by the work of Kalman and others (57), Roberts and Stout (88),and also three important discussions from the hloscow Congress (27, 84, 95). T h e application of control computers to alkylation plants (75),
INDUSTRIAL AND ENGINEERINGCHEMISTRY
to butane isomerization ( 4 ) , and to natural gas (5Y) and leased \vel1 operations (65)were also discussed.
Control Theory Control theory has been furthercd by many magazine articles during the past year. Control engineers will be especially interested in the general theory articles of Buckley 170’), Chatterjee (ZO), and Mamzic ( 7 7 ) : and in the discussion of the root locus method given by Teodorchik and Bendikov 197). The superb article by Kalman (56) reviewing the \\hole field of automatic control theory is recommended to the engineer with the proper backsgound. Specific control theory topics Tvorthy of the process industry man‘s attention include the relatively new but tremendously important field of adaptive control. Especially lvorthy of note here are the articles by Gibson (.?5-37), by Valstar [707), and by Eklund (29). Konlinear control was described by Gibson (38) and Ku (64,and sampleddata systems !\’ere described by Jury (54, 5.5) and Thaler (98). Newer topics sure to become very important in the years to come are dynamic programming (70) and the dynamic optimization of chemical processes. T h e JACC included the presentation of three reports (9, 73, 67) gibing a discussion of the dynamic control optimization of the generalized chemical processing model of Williams and Otto (709). While significant contributions in their own right, these point u p the extreme difficulty ol obtaining complete real-time. dynamic optimization of chemical processes. T h e report by Boydston (13) optimizes a linear version of the reactor alone from the generalized model plant. Beecher and Gould ( 9 ) present the required model for a nonlinear optimization but do not have enough available computing capacity for a realtime solution to the problem. Kipiniak and Gould (67) present a scheme Cor precomputing the required control responses for optimization situations. The more elementary aspects of control theory Lvere covered by b’illiams and Lauher ( 707) and by Meadows (74) on the graphical techniques of control system design. A series of articles by Williams on systems engineering (704) is being presented currently.
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processes were described by Wotring and McAveeney ( 7 70). T h e very important topic of sampling system design was discussed by Houser (48, 49) and Percy j P 3 ) , while Grantom a n d others discussed the equally important topic of analyzer dynamics ( d o ) , much neglected until now. ’The status of electronic control systems in this country has been reviewed by O‘Connor (771, tvhile Barlow and M a y (7) covered that of England and the Continent. Bernard ivrote on instrumentation costs (72) a n d Parish on maintenance (80). ‘The well knoivn column on instrumrntation, formerly written by Wall (702), has been taken over by Stirling and Ho ( M ) . Other important applications studies were those on gas pipeline operation by Heard 147): Drinker (25), and Marton ( 7 3 ) .
Process Dynamics Theory and Experimental Results T h e literature during 1960 again included several important contributions presenting new process dynamics information o r theoretical discussions 3f their determination o r effects upon control response. Distillation columns were discussed by Haines (42),Huckaba a n d Danly 157), Gerardin (34), and Rosenbrock and associates (89). Ceaglske described a theoretical study of absorption column dynamics i / 9 ) . T h e important firld of fluid dynamics, as related to process control, was thr subject of studies by Boyle and Nigh ( 7 J ) , Ceaglske 178): Head and others ( d 6 ) ,and hietzner and Taylor (75). T h e effect of backmixing on reactor design was discussed by Levenspiel a n d BischofT 168),and Orcutt and L a m b 179) described the requirrment for catalytic reactor stabi!ity. P a d s and associates 182) made a very important study of instrument accuracy in obtaining reactor dynamics data, and Solheim (93) presented a thorough study of reactor control measures. Haveraaen (45)covered gas handling systems. Other topics covered were a study of heat exchanger dynamics by Morris (76) and the first full study of evaporators, of which this author is aware, as carried out by Johnson (53). T h e subject of steam boiler dynamics was popular a t the IFAC Congress a n d drew three reports (30:3 2 8 6 ) . T h e three revielvs given a t the JACC on process dynamics present the best available review of their separate fields to date. These covered the subjecis of distillation ( 9 0 ) . reactor dynamics ( 6 6 ) , and heat exchangers (705).
Instrumentation I n instrumentation the most spectacular developments were again made by the manufacturers and users of gas chromatography equipment. Great strides Ivere made both in high-temperature use of these instruments and in their operating speed (58). Their applications to process control are covered in t\vo very good articles (33, 703). T h e use of chromatography for the preparation of pure materials (85) and for liquid analyses (70) was also covered. Other important developments occurred in the infrared field (8,72) a n d in mass flowmeters (44, 97). Ultrasonic viscometers for polymer
This review and its companion expanded bibliography has covered the periods Dec. 1, 1959 to Nov. 30, 1960, for domestic publications, and Oct. 1, 1959 to Sept. 30, 1960 for foreign publications.
Chemical Engineering Fundamentals Review
General Several other topics which have appeared in the literature during the past year should be brought to the reader’s attention. These include the applications of statistics to chemical process improvement, as developed by Hunter (52) and Tidwell (700),and the discussions of process optimization by computer as given by Berg (77) and Taborek (96). These topics are important because as aspects of systems engineering they must be applied alonp with the usual process control a n d process dynamics studies to assure optimum results. I n the field of analog computers as related to process control, Freeman and Owen showed how to predict controller settings (37), Ames showed how rate constants a n d other important process parameters may be developed from process mathematical models (2),a n d Kovach a n d Comley described some simple analog circuits for representing various nonlinearities common in control systems (63). A n important new development in analog computers, the dynamic storage computer, was described by Andrews 13). literature Cited (1) Ahrendt, W. R., Savant, C. H.. Jr., “Scrvomechanism Practice.” McGrawHill, New York, 1960.
(2) Ames. W. F., ISD. EHG. CHE\f., 52, 517 (1960). (3) Xndrews, J. hf.: Instr. Control Systems 33, 1540 (1960). (4) Auricoste, J. G., “Proc. 1st Congress, IFAC, Moscow.” p. 166, Butterivorths Scientific Publications, London, 1960. (5) Balise, P. L., ISB Journal 7 , 48 (February 1960). (6) Ibid.,p. 72 (March 1960). (7) Barlow, Derek, May. E. D., Control EnF. 7, 103 (June 1960’1; p. 107 (hugust 1960); p. 105 (October 1960). (8) Bartz, A . M., Znslr. Con!rol Syrtems 33, 458 (1960). (9) Beechar, A. E., Gould, L. A., Paper AIEE CP 60-980, Joint .Automatic Control Conf.: Cambridge. Mass., September 1960. (10) Bellman, R . , Kalaba? R.. “Proc. 1st Congress. IFAC, MOSCOW,”p. 122, Butterworths Scientific Publications, London, 1960. (11) Berg, Clyd?, Chem. Eng. Progr. 38, 42 (August 1960). 112) Bernard. J. LV., Contiol Ew. , 7., 143 ’ (:April 1966). (13) Boydston, R. E., Paper AIEE CP-GO979, Joint Automatic Control Conf., Cambridge, Mass., September 1960. (14) Boyle. R. E., Nigh, M. T., ISil Joiirrinl 7, 94 (May 1960). (15) Brandon, D. B., IND.C N ~Cliehc. . 52, 814 (1960). (16) Buckley, P. S., “Proc. 1st C:ongrcss, IFAC, Moscow,” p. 1709, Butterivorths Scientific Publications, London, 1960. (17) Caldwell, W. I., Coon, G. A . , ZOSS, L. M.. “Frequency Response for Process Control,” McGraw-Hill. New York, 1959. (18) Ceaglske, N. H., rl.1.Ch.E. Journal 5 , 524 (1959). (19) Ceaglske, N. H.,“Proc. 1 s t Congrrss. IF.AC, Moscow, p. 489, Butterworths Scientific Publications, London, 1960. (20) Chatterjee, H. K . , Ibid., p. 831. (21) Chem. Eng. 67, 110 (NOV.14, 1960). (22) Conine, Ernest, Ibid., 67, 181 (Sept. 19, 1960). (23) Control En,?. 7, 40 (November;‘1960). (24) D’Azzo. 3. J . , Houpis, C. H . , Control System Analysis and Synthesis,” McGraw-Hill, New York, 1960. (25) Drinker, P. H., Znslr. Control Systenzs 33, 972 (1960). (26) ~,Eckman. D. P., IS.4 Journal 7, 7 8 (April 1960). (27) Eckrnan, D. P., Lefkowitz. I., “Proc. 1st Congress, TFAC, MOSCOW,” p. 946, Butterworths Scientific Publications, London, 1960. (28) Eisenhardt, R . D., Williams, T. J., Control Eng. 7 , 103 (November 1960). (29) Eklund. Karl, Ibid., 7, 161 (.April 1960). (30) Ergin, E. I., Ling, C., ‘.Proc. 1St I-
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Chemical Engineering Fundamentals Review
Congress, IFAC, Moscow,” p. 1261, Butterworths Scientific Publications, London, 1960. (31) Freeman, L. R., Owen, R. L., IS11 Journal 7 , 52 (October 1960). (32) Frensch, J., “Proc. 1st Congress, IFAC;, MOSCOW.” p. 478, Butterworths Scientific Publications, London, 1960. (33) Fourroux, M. M.. Karasek, F. W.. lyiphtman, R . E.. I S A Joul-nal 7. 76 1960); 021 Gas J, 5 8 , 96 ( M k c h 21. 1960). (34) .Gera;din, L.. “Proc. 1st Congress, IFAC, Moscow,‘ p. 917, Butterworths Scientific Publications, London, 1960. (35) Gibson, J. E., Control En?. 7 , 113 (August 1960). (36) hid., p. 109 (October 1960). (37) Gibson, J. E., “Proc. 1st Congress, IFAC, Moscow,” p. 147, Butterworths scientific Publications, London, 1960. (38) Gibson, J. E., ISA Journai 6 , 46 (December 1959). (39) Grabbe, E. M., “Proc. 1st Congress, IFAC, Moscow, ’ p. 1695. Butterworths Scientific Publications, London, 1960. (40) Grantom, R. L., Hougen. J. O., Dreifke. G. E.. Control Eng. 7 , 113 (May 1960); 104 (July 1960). (41) Grohskoff, Herbert, Ibid., 7, 70 (February 1960). (42) Haines, H. W.! Jr., IND.ENG.CHEM. 52, 662 (1960). (43) Hall, C. R., Chem. Eng. Progr. 56, 62 (February 1960). (44) Halsell, C. M., IS.1 Journal 7, 49 (June 1960). (45) Haveraaen, S., “Proc. 1st Congress. IFAC, MOSCOW,” p. 614, Butterworths Scientific Publications, London, 1960. (46) Head, F. E., Hougen, J. O., Walsh, R. A . , Ibid., p. 495. (47) Heard, T. C., Oil Gas J . 58, 121 (March 14, 1960). (48) Houser, E. A,, Control Eng. 7 , 129 (August 1960). (491 Houser, E. A., ISA Journal 7, 95 (September 1960). (50) Hubbard, R. M., Ibid., 7 , 67-69 (August 1960) ; p. 81 (September 1960). (51) Huckaba, C. E., Danly, D. E., A . L C h . E . Journal 6, 335 (1960). (52) Hunter, J. S., Chem. Eng. 67, 193 (Sept. 19. 1960). (53) Johnson, D. E., IS.4 Journal 7, 46 (July 1960). (54) Jury, E. I.: “Proc. 1st Congress. IFAC, Moscow,” p. 240, Butterworth Scientific Publications, London, 1960. (55) Jury, E. I., IS.4 Journal 7, 68 (June 1960). (56) Kalman, R . E., “Proc. 1st Congress, IFAC, MOSCOW,” p. 2020, Butterworths Scientific Publications, London, 1960. (57) Kalman, R . E., Lapidus, L., Shapiro, E., Chem. En,g. Progr. 56, 55 (February 1960). (58) Karasek, F. W., Ayers, B. O., ISA Journal 7, 70 (March 1960).
(59) Rarcher, Bill, .Jacobson, Hugh, I~isfr. Control Systems 32, 1824 (1959). (60) Karp. H. R., Control En,?. 7 , 20 (April 1960). (61) Ripiniak, W., Gould, L. A,, Paper AIEE TP-60-982, Joint Automatic Control Conference, Cambridge, Mass., September 1960. (62) Kobrinskii, A. E., Bolkhovitin, S. V.; others, “Proc. 1st Congress, IFAC. MOSCOW,” p. 1119, Butterworths Scientific Publications. London, 1960. (63) Kovach, L. D., Comley, W.! Control En,?. 7 , 135 (November 1960). (64) Ku. Y. H.; “Proc. 1st Congress, IFAC. MOSCOW,’’p. 548, Butterworths Scientific Publications, London, 1960. (65) Lacy: LV. E., Instr. Control Systems 33, 642 (1960). (66) ,Lapidus, L., A.1.Ch.E. Paper No. 3, Joint Automatic Control Conference, Cambridge, Mass., September 1960. (67) Lauer, Henri, Lesnick, R . iY.,hlatson. L. E.. “Servomechanism Fundamentals,” 2nd ed., McGraw-Hill, New York, 1960. (68) Levenspirl, Octave, Bischoff, K . B., IND.ENG.CHEM.51, 1431 (1959). (69) Madigan, J. M.. Chem. Enf. P r q r . 5 6 , 63 (May 1960). (70) Maley. L. A,, ISA Instrumental Methods of Analysis Symposium, Montreal, June 1960. (71) Mamzic, C. L., ZSA Journal 7 , 63 (June 1960). (72) Martin. A. E., Reid: A. M., Smart, J., Control 2, 108 (December 1959): 3, 91 (January 1960). (73) Marton, F. D., Instr. Control Systems 32, 1850 (1959); 33, 112, 228, 462, 622, 816. 984, 1162, 1358, 1531, 1751 (1960). (74) Meadows, h-. G., Control 2, 117 (November 1959); 3, 133 (February 1960) : p. 105 (March 1960). (75) Metzner; A. B., Taylor, J. S , A.I.C/i.E. Journal 6, 109 (1960). (76) Morris, H . J., “Proc. 1st Congress, IFAC, Moscow,” p. 559, Butterworths Scientific Publications, London, 1960. (77) O’Connor, W. F., Instr. Control Systems 33, 1742 (1960). (78) Oldenburger, R. F., Norwood, R . E., others, ISA Journal 7 , 68 (November 1960). (79) Orcutt, J. C., Lamb, D. E., “Proc. 1st Congress. IFAC, MOSCOW,” p. 1341, Butterworths Scientific Publications, London, 1960. (80) Parish, C. L., ZSA Journal 7, 84 (Januarv 1960). (81) Parsons, J. R., Tolin, E. D., Andrews, A. J.. C o n h l Eng. 7, 150 (September 1960). (82) Pauls, A . C.. Olt, R. G., otherq, ISA Journal 7 , 46 (Xovember 1960). (83) Percy, L. E,, Ins&. Confrol .Systems 33, 1755 (1960). (84) Phister, M , Jr., “Proc. 1st Congress,
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INDUSTRIAL AND ENGINEERINGCHEMISTRY
IFAC, Moscow,” p. 305, Butterworths Scientific Publications, London, 1960. (85) Porter, R. S.,Johnson, J. F., IND. ENG.CHEM.52, 691 (1960). (86) Quack, R., Schneider, A,, “Proc. 1st Congress. IF;\C, Moscow,” p. 1222, Butterworths Scientific Publications, London, 1960. (87) Ragazzini, J. R., Paper 55-NY60, 15th Annual ISA Instrument-Automation Conference and Exhibit. New York, September 1960. (88) Roberts, S. M.. Stout, T. IM., Instr. Control Systems 32, 1854 (1959). (89) Rosenbrock, H. H., Tavendale, A. B., others, “Proc. 1st Congress, IFXC, MOSCOW,” p. 1277, Butterworths Scientific Publications, London, 1960. (90) Rothfus, R . R., Archer, D. H., A.1.Ch.E. Paper No. 2, Joint Automatic Control Conference, Cambridge, Mass., September 1960. (91) Siev, Robert, Znstr. Control Systems 33, 966 (1960). (92) Slater, L. E., ZSA Journal 7, 70 (July 1960). (93) Solheim, 0. A,, Control Eng. 7, 107 (April 1960). (94) Stirling, P. H., Ho, Henry, IND. ENG.CHEM.52, 61A (April 1960); 75A (June 1960); 594 (July 1960); 65A (August 1960) ; 63A (September 1960) ; 63A (October 1960) ; 61A (November 1960). (95) Stout, T. M., “Proc. 1st Congress, IFAC, MOSCOW,” p. 191, Butterworths Scientific Publications, London, 1960. (96) Taborek: J. J., Chem. Eng. Progr. 56, 37 (August 1960). (97) Teodorchik, K. F., Bendikov, G. A , , “Proc. 1st Congress, IFAC, MOSCOW,” p. 1031, Butterworths Scientific Puhlications, London, 1960. (98) Thaler, G. J., Control Eng. 7 , 123 (January 1960). (99) Thal-Larsen, Herman, ISA Journal 7, 100 (May 1960). (100) Tidwell, P. W., IND.ENG.CHEM.52, 510 (1960). (101) Valstar, J. E., ISA Journal 7, 74 (October 1960). (102) Wall, R. F., IND. ENG. CHEM.51, 71A (December 1959); 52, 105.4 (January 1960) ; 61.4 (February 1960) ; 55A (March 1960); 55A (May 1960). (103) Wherry, T. C., Chem. Eng. Progr. 5 6 , 49 (September 1960). (104) M’illiams, T. J , Chem. En:. 67, 121 (Feb. 8, 1960); 131 (March 7, 1960); 139 (April 4,1960) ; 121 (May 2, 1960) ; 97 (May 30,1960) ; 113 (June 27, 1960) ; 119 (July 25, 1960); 127 (Aug. 22, 1960); 181 (Oct. 17, 1960); 227 (Nov. 14, 1960). (105) Williams, T. J., Paper 54-NY60, 15th Annual ISA Instrument-Automation Conference and Exhibit, New York, September 1960. (106) Williams! T . J., Lauher, V. A , , Chem. Eng. Progr. 56, 71 (February 1960). (107) Williams, T. J., Lauher, V. A , , Petrol. Refiner 38, 105 (December 1959); 39, 171 (January 1960); 132 (February 1960); 167 (March 1960); 173 (April 1960); 197 (May 1960); 147 (October 1960); 247 (November 1960). (108) Williams, T. J., Morris, H. J., A.1.Ch.E. Preprint No. 1, Joint Automatic Control Conference, Cambridge, Mass., September 1960. (109) Williams, T. J., Otto, R. E., AIEE Paper CP-60-119,AIEE Winter General Conference, New York, January 1960. (110) Wotring, A. W., McAveeney, T. B., ISA Journal 7, 67 (October 1960).
