---11111111-•-----=--------~S=i AIChE special section ) SEPARATIONS: A SHORT HISTORY AND A CLOUDY CRYSTAL BALL PHIL WANKAT Purdue University eparations have always been and will continue to be still was invented by Jabir ibn Rayyan (aka Geber) in the late critically important in the processing of chemicals. 8th or early 9th century. Similar stills are currently in use in SIt is common to note that 40 to 70 % of both capital some whiskey distilleries and for distilling rose oil.[ 6l By the and operating costs in industry are due to separations_[!, P· lJ 14th century the production of strong alcoholic drinks had 4 18 It has been estimated that 15 % of the world's energy use become an industry. [ , P· l The first book on distillation was is required by separations.[2l Because of their industrial Hieronymus Brunschwig's Liber de arte distillandi published importance separations have always played an important in the early 1500s and translated into English in 1527_[7J part in chemical engineering education and in the chemical Brunschwig's book (Figure 1) is an apothecary with distilla­ engineering literature. tion used to produce various medicines from plants. Petroleum distillation was started in England in the 17th century and coal HISTORY OF SEPARATIONS tar distillation was first patented in 1746_[4, P· 35l Fractionation The beginning of separations apparently occurred before of coal tar into naphtha, kerosene, lubricating oil, and paraffin 3 recorded history. Egyptians used filtration to filter grape was patented in England in 1850. [ l The first oil refinery con­ 3 8990 juice over 5,000 years ago. [ , PP· l Aristotle mentioned that structed in 1860 in Pennsylvania used simple batch stills and 4 16 pure water can be obtained by evaporating sea water. [ , P· l A collected wide-boiling fractions as the distillation proceeded. combination of coagulation of impurities, evaporation, and crystallization used for salt manufacture were commonly in Phil Wankat has a joint appointment in 90 4 21 5 229 233 use by the 16th centuryY-P ' · PP ' · PP - l Similar practices Chemical Engineering and in Engineering 5 233 Education at Purdue University. He has a were still in use in India in 1980. [ , P· l Pressing, evaporation, B.S. ChE from Purdue, a Ph.D. from Princ­ and crystallization were commonly in use for sugar production eton, and an M.S. Ed from Purdue. He is by the 16th century.[4, P· 23 l the associate editor of GEE. Distillation, particularly batch distillation, has a long history. Mesopotamian clay distillation vessels with lids shaped to col­ lect the condensed volatile distillate have been dated to ~3500 BCE. [6l Alchemists in the first century AD in Alexandria used 4 16 a variety of simple batch stills or retorts_[ , P· l The alembic © Copyright ChE Division of ASEE 2009 286 Chemical Engineering Education ·_.~-/;;a~ ·. {J-ll/u£.,,,:: . ,..J}• ~o. ✓ •· 'L..~~ --P' - / ;;_/ <L ~ ' . 1.ibetr 'Oe aute iaiftil' htndi be CfompcfitfG. ·;z,as (!~cJ,-~et roaren kun,t 3u t>jJt~niaen t,i~ j ., rCtmpofita -on frmplaaa/~nb bl ~aidt t~cfaurue pattpcnv!-cnt f~at3 ~ ~trne gt~ ,w«)ica.riw~ie b»famliri rtef41.len w be bii~ertt ~ 2lr~li1 lt'11b bur~ ~~petitnefl ~ mil: J~eeonfmo b:iif~wicf ~ff gcclnbc ~ii ~e.offmbatt ~ii not'f ~enc bic e6 begcrc+ Figure 1. Cover page to Hieronymus Brunschwig's Liber de arte distillandi. Courtesy of Donald F. and Mildred Topp Othmer Library of Chemical History, Chemical Heritage Foundation, Philadelphia, PA. Vol. 43, No. 4, Fall 2009 287 1 257 Horizontal stills with improved performance were used in the Davis,l1 · P· l who notes that safety valves are useful if they are early 19th century for alcohol purification. An improved still kept in working order. Packing was apparently first employed was developed in 1818 by Cellier in France who developed in 1820 and was patented in 1847.[16l The problem of breaking 4 35 a vertical bubble plate still for alcohol purification_[ , P· l the ethanol water azeotrope was solved by Young in 1902 with In Victorian times large estates often had batch distillation a batch, azeotropic distillation process using benzene as the systems to prepare drugs and concentrated liquors. Popular entrainer to produce the first observed ternary azeotrope as books on distillation were available for this market. [9l In his the distillate product. The batch process was converted to a Handbook ofChemical Engineering, published in 1901 and in continuous azeotropic distillation by Keyes in 1928Y7l an enlarged edition in 1904, George Davis clearly developed In the early 1920s petroleum refineries had not adopted 0 the unit operations idea (not by this name) for distillationY · more modem fractionation systems and were using horizon­ 100 103 11 PP· - , l Before this, the distillation of each chemical was tal stills directly heated on the bottom in conjunction with studied separately. It is notable that the 2nd edition of C. partial condensation to distil petroleum. These systems were 12 S. Robinson's The Elements of Fractional Distillation[ i not very efficient and considerable redistilling was required. has elements of both the unit operations generalization and Modernization of distillation in refineries occurred in the individual chapters for distillation of a number of chemicals 1920s when W.K. Lewis was hired as a consultant by the such as ethanol. By the fourth edition, extensively revised by Standard Oil Company of New Jersey and introduced vertical 3 Ed Gilliland,l1 l the unit operations approach dominated and 8 305306 fractionation systems.[ , PP· l By the 1920s and 1930s the distillation of specific chemicals were relegated to examples. 12 18 schematics of continuous distillation columns in textbooks[ ' ' 19 20 12 The Elements of Fractional Distillation may have been the l and in Perry's HandbooAf. · section i look fairly modem except first chemical engineering book to also become popular with a that valve trays and structured packings had not been invented nontechnical audience-it was very popular with bootleggers yet. Heat recovery in distillation was common by 1923Y-P 575l 14 85 in the 1920s and 1930s.[ ,p. l Batch distillation was important The histories of distillation equipment, distillation control, enough to attract the attention of Lord Rayleigh who appar­ and azeotropic and extractive distillation were reviewed by 5 ently did the first theoretical analysis of the methodY l Fair,l1 6l Buckley,l2 1l and Othmer,l1 7l respectively, for the 75th The first continuous distillation appears to have been de­ anniversary of AIChE. veloped by Aeneas Coffey in 1830. He developed a vertical Theoretical analysis of continuous binary distillation was 4 perforated plate column for alcohol purification (Figure 2). [ , PP· first achieved by Sorel, who was interested in the distillation 35 36 11 ' l This still was equipped to preheat the feed by exchange of alcoholP2l Sorel's method is accurate, but confusing and with the condensing distillate and the bottoms. Davis[lll shows laborious since a trial-and-error calculation was required on open-steam distillation systems and several examples of every stage. Binary distillation was analyzed graphically with­ methods to reduce energy. In 1900 vertical perforated plate out trial-and-error by Ponchon[23 J and Savarit[24l independently. columns quite similar to modem equipment were introduced Lewis[25J realized that in many cases the vapor and liquid molar 4 36 9 for distillation of tar. [ , P· ' al Safety in tar stills is discussed by flow rates are approximately constant-if they are assumed to Figure 2. "The Coffey still of 1830 for distilling alco­ hol from fermented mash, using perforated plates. 1. Boiler. 3. Stripping col­ umn. 4. Rectifying column. 6. Feed. 8. Condenser. " Reprinted with permission from Davies, J. T., "Chemi­ cal Engineering: How Did it Begin and Develop?" in Furter, WF. (Ed.), History of Chemical Engineering, American Chemical Soci­ ety, Washington, D.C., Ad- vances in Chemistry Series, 190, 15-43 (1980). Copyright 1980 American Chemical Society. 288 Chemical Engineering Education be constant Sorel's trial-and-error procedure is not required. Gibbs studied the thermodynamics of growing crystal surfaces The simplified Lewis method was converted to a graphical at equilibrium and realized that thermodynamics was often method by McCabe and Thiele. [26l Because McCabe-Thiele not sufficient to explain the crystal growth.[36l McCabe[37l plots clarified the physical reasons why column distillation found that the deposition rate/unit area is often linear in works, the method was rapidly adopted. While no longer used supersaturation and deposits grow at a uniform rate. Unfor­ for design, McCabe-Thiele diagrams are commonly used to tunately, McCabe's L law often does not holdY6l Industrial teach distillation. Solutions for multicomponent distillation scale crystallizers in 1934[33l do not look very different than are much more complicated, particularly if there are non-dis­ many modem crystallizers. The important theory of crystal tributing light and heavy non-keys. Initially, stage-by-stage size distribution was developed by Randolph and LarsonY9l 7 28 36 methods were adapted to multicomponent distillation,(2 ' l Hulbert[ l reviewed crystallization for the 75th anniversary but closure remained a problem. Numerous computer solution of AIChE, and more recent advances in crystal engineering methods were developed after Amundson and Pontinen[29J are reviewed by Doherty. [4oJ Precipitation is similar to crystal­ realized that distillation equations could be conveniently lization except the product is usually amorphous with a poorly solved after they were put into matrix form. One of the more defined shape and structure. Precipitation is often used as a robust and common methods still used in commercial simula­ first cut before crystallization. Early workers did not delineate tors was Naphtali and Sandholm's[30] linearization of all the between precipitation and crystallization and many early equations.