The Catalyst

MIT professor Warren “Doc” Lewis helped shape modern chemical engineering.

What strikes you first in the many surviving pictures of Warren K. Lewis is the hard punch of his stare. Even at a distance of 60 or 70 years, you can feel him in the back of your brain, probing for any idea that is half baked or uninformed. Sometimes you can also see a hint of a smile, a sense of mischief that belies his ability to hang people out to dry.

These pictures have been carefully preserved in MIT’s museum because Lewis can reasonably be said to have fathered contemporary chemical engineering. He coauthored the profession’s seminal U.S. text. And as the first chair of MIT’s chemical-engineering department and a member of the faculty for nearly four decades, he helped shape the generations of engineers who defined modern chemical engineering.

In the late 1930s, Lewis and a colleague made a breakthrough in the manufacture of gasoline that gave the Allies the great advantage of a steady supply of high-octane aviation fuel during World War II. He played a key role in the Manhattan Project. And when the war was over, he chaired the committee that defined how MIT would respond to the challenges that conflict had raised.

But within the MIT community, he was most famous as a teacher, a perfect expression of a “tool” culture of rigor and mental toughness in which any discussion of one’s feelings was irrelevant. According to a collection of anecdotes published by former students upon his retirement, when “Doc” Lewis entered a classroom, he would charge in, slam his books down, peel his jacket off, and roll up his sleeves. His wire-rimmed glasses hunted up and down the tiers of students – mostly young men – squirming in front of him as they willed themselves invisible. “Davis! Name me one natural law that is true without exception!” Davis would say something. “That was the damnest, poorest, and most asinine recitation that I have heard in all the years of my experience as a teacher! Jones!” Jones would pause for two seconds to collect his thoughts. “Next man! Smith!” Smith’s face would go white. Once, Lewis recognized a student’s name in a school dramatic production. He called him over. “I’ve always been proud that Course X leaves little time for outside activities,” he said. “You have proved me wrong so far and I’m glad you have. But don’t push your luck too far!”

Of course, he was immensely loved, the way that drill sergeants are, and for many of the same reasons. The message of his manner was that engineers were an elite band, a tribe of special people called to apply their extraordinary skills in service to the community. They required a certain quality of character, a loyalty to unvarnished fact that rose above politics or profit. And even within this tribe, chemical engineers had a little something extra. They were among the first to see their field as a unified engineering science, not merely a collection of isolated specialties. Lewis was there to make sure the undeserving – blockheads, as he was known to call them – did not sneak by, and he was not shy about exercising that responsibility.

But once you got through, if you did, you moved in a special circle. You knew how things worked and were in a position to change them. Everyone lived in the world that you made.

The Birth of Unit Operations
Lewis matriculated at MIT in 1901. While today’s curriculum is heavy in mathematics and basic science, students in the early 1900s spent much more of their time in drafting rooms, shops, and foundries, learning how to run and repair furnaces and boilers, presses and blenders, generators and turbines. As the Institute responded to the management demands of specific industries, the goal, as the MIT catalogue explained, was to bring students “into direct contact with the material problems of [their] future profession.” By the end of the 19th century, industrial demands reflected the growing frequency with which gases and liquids were handled on a widening range of production scales, in the manufacture of such things as alcohol and alcohol products, acids, fuels, paints, bleaches, dyes, glass, soaps, oils, lubricants, metals, and gunpowder. MIT reacted to this growth by hiring several new faculty members to expand its offerings in what was then referred to as “industrial chemistry.” One of these was a farm boy from Delaware named Lewis.

When Lewis joined the faculty in 1910, the department was changing quickly. An earlier hire, William H. Walker, had been a partner with Arthur D. Little in the firm Little and Walker, one of the country’s first industrial-consulting firms. (It went on to become Arthur D. Little.) Walker’s experiences had given him an intimate acquaintance with the burgeoning chemical industries. Along with Little, an 1885 MIT graduate and a member of an MIT visiting committee, Walker knew that the days of teaching the management of specific machines for specific industries were over. There were just too many machines, changing too rapidly, organized in too many different combinations. The industrial-chemistry program was becoming incoherent; a prospective employer could not know for certain what a graduate knew. The field needed recentering and simplification.

Walker and Little had an idea of how to go about it. While modern chemical industries had become tremendously diverse, almost all drew from the same short list of processes: heating and cooling, mixing and separating, vaporizing and condensing, grinding and crystallizing, and so on. What differentiated one industry from another was the sequence in which these processes were strung together and their operating parameters – scale, temperature, pressure, rate, and so on. Walker and Little’s idea was to -refocus industrial-chemistry education on these core processes. -Little called this perspective “unit operations.”

With input from Little, Walker and Lewis undertook the mammoth task of precisely defining unit operations and figuring out how best to teach students to perform them. They faced two obstacles. The first was the challenge of reconceptualizing the science of physical chemistry in terms that made sense from an engineering point of view. To lampoon the difference between them slightly, scientists are interested in whether A causes B; chemical engineers are interested in how much of A makes how much of B over what ranges of temperature, pressure, and time, preferably to at least three digits of precision. All of that information existed, but it was buried deep in the science. Fortunately, Lewis had an immense talent for squeezing out important regularities from even the most abstract theory. (Some of his students suspected that he had devised his own system for using a slide rule to solve problems to an extraordinary level of resolution.)

A second problem was finding a way to give graduates experience with industrial processes. “Science by itself,” Walker told a colleague, “produces a very badly deformed man who becomes rounded out into a useful creative being only with great difficulty.” MIT could not afford to buy and maintain an inventory of up-to-date industrial machines. An education centered on unit operations would therefore need some kind of internship program to allow students direct experience with the cutting-edge machines of the day, wherever they were. Walker, with Little’s help, set to work.

As Walker and Lewis hammered the new curriculum into shape, they realized that they had done more than find a new way to teach an old subject; they had revolutionized the field. Industrial chemists had always gotten their professional identities from their particular industries. Somebody who worked with soap was a soap guy. He would no more think of crossing over to acids or paints than to poetry. But a graduate in unit operations was sector independent. He or she could work, quite literally, anywhere. A text on the unit operations of distillation, The Elements of Fractional Distillation, written by MIT professor Clark S. Robinson, became a handbook for the bootlegging industry during Prohibition.

Another change sparked by the unit operations approach was that where industrial chemists optimized the performance of individual machines, the new engineers designed entire production processes from beginning to end, from loading dock to loading dock, to any desired scale. The old system favored “batch production,” stop-and-go processes in which optimization was defined at the level of the machine. Unit operations stressed gearing the entire production cycle to a single speed and allowing it to run continuously.

The name “chemical engineer” had been in use for some decades – MIT had initiated its chemistry curriculum under the title chemistry and chemical engineering in 1888 – but tying the term to unit operations gave it a new and specific meaning. Walker named the internship program the School of Chemical Engineering Practice. In 1920, Chemical Engineering became a separate department at MIT, with Lewis as its first chair. And in 1923, Walker, Lewis, and William H. McAdams (another new hire), published Principles of Chemical Engineering, which would become the foundational textbook of the new field.

Meantime, out in the world, immense changes were buffeting the profession. After the outbreak of World War I, the U.S. seized all German-owned patents and began licensing them to American companies. This was a huge event in the chemicals world, unseating Germany from its near total domination of industrial chemistry. (By 1912, 98 percent of all the patent applications in industrial chemistry registered at the U.S. Patent Office belonged to German firms.) The confiscation of German patents opened immense opportunities for chemistry-related industries and therefore for chemical engineers. Students began to pour into the field. Lewis was there to make sure only those who made the grade got through, although he was known to give struggling students extra help. Despite the high standards he helped set, quite a few students met them. Between 1905 and 1909, MIT awarded 65 bachelor’s degrees in chemical engineering, between 1920 and 1924, 419.

Unit Operations in Action
Lewis himself offers perhaps the best example of the new profession at work. During the 1920s and 1930s, one of the few clouds shadowing the explosive growth of the American automobile industry was the high cost and difficulty of refining high-grade fuel. A significant fraction of that cost could be traced to one vexing problem: all the refining techniques then in use produced a layer of carbon that gunked up the equipment, forcing operators to interrupt the refining process after frustratingly short periods of operation. The only way to get continuous operation was to build two refineries and put one online when the other was being cleaned. Many people took a crack at this problem; eventually Doc Lewis got involved.

After beating his head against the wall for a bit, Lewis, who was working with another MIT professor, Edwin R. Gilliland, dreamed up an ingenious solution to the problem. By the mid-1930s, refinery engineers had discovered materials, typically clays, that accelerate the chemical reactions that shorten hydrocarbon molecules and improve their octane ratings. Engineers arranged clay grains on a fixed bed and passed hydrocarbon vapor through them. -Unfortunately, the clay particles quickly became covered with carbon. To address this problem, engineers began experimenting with fluidized beds, in which hydrocarbon vapors are forced through the clay grains from below, causing the grains to float. Lewis knew that, in theory, it would be possible to persuade these grains to flow into a separate tank for cleaning. Since the particles were too abrasive to be handled by pumps or conveyors, Lewis borrowed an idea from fluid mechanics – unit operations in action – and used the pressure generated by forcing the hydrocarbon-vapor and grain mixture through a column to drive the particles where they were needed. Today, these columns define much refinery architecture.

The first refinery built around the process, called fluid catalytic cracking (FCC), started operation in 1942. It worked brilliantly and was immediately pressed into use for the war, giving the Allies adequate supplies of fuel, especially the high-octane fuel used in airplanes. After the war, FCC was generalized into a whole new unit operation, the fluidization and transport of solids, and spread to dozens of sectors, from uranium processing and coal gasification to the incineration of solid waste and the manufacture of semiconductors and soy sauce.

Lewis retired from MIT in 1948 and died in 1975. He did so much to change the world, and yet he would not have recognized the landscape he helped create. Today, 56 percent of Course X undergraduate students are female, whereas Lewis operated in a man’s world; women were unusual and put a cramp in his colorful style. Likewise, chemical engineering is increasingly shifting its focus to biotechnology, and administrators at MIT now worry quite a bit about how their students are feeling. Most important, the fraternity of the engineer has been at least partially dissolved by the increasing complexity of industrial processes. Today, more than ever, engineers do anything and work with anybody to solve the problems at hand. The definition of the very term “engineer” is beginning to blur.

But Lewis would have had every reason to look on his legacy with pride. In helping establish a new profession, he gave many young men (and a few young women) the common identity of chemical engineer. He gave them a virtuous calling. He gave them their grip on life. Even more broadly, Lewis was a great problem solver: optimistic, ingenious, indefatigable. It is hard to look at his photos and not want to break the glass, to turn him loose on the problems caused by our own damned blockheadedness.

Sidebar: The Prose That Launched 10,000 Careers
Excerpted from the preface to the first edition of Principles of Chemical Engineering

Just as the arts of tanning and dyeing were practiced long before the scientific principles upon which they depend were known, so also the practice of Chemical Engineering preceded any analysis or exposition of the principles upon which such practice is based. The unit operations of chemical engineering have in some instances been developed to such an extent in individual industries that the operation is looked upon as a special one adapted to these conditions alone, and is, therefore, not frequently used by other industries. All important unit operations have much in common, and if the underlying principles upon which the rational design and operation of basic types of engineering equipment depend are understood, their successful adaptation to manufacturing processes becomes a matter of good management rather than of good fortune.

In this book we have attempted to recall to the reader’s mind those principles of science upon which chemical engineering operations are based, and then to develop methods for applying these principles to the solution of such problems as present themselves in chemical engineering practice. We have selected for treatment basic operations common to all chemical industries, rather than details of specific processes, and so far as is now possible, the treatment is mathematically quantitative as well as qualitatively descriptive. We venture to hope that the book will stimulate engineers to design apparatus adapted for any particular purpose, rather than just to build it and then to rely on large scale experimentation with expensive changes in construction to effect efficient operation.

William H. Walker
Warren K. Lewis
William H. McAdams
Cambridge, Mass., February, 1923

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