Scale drove adoption of chemical engineering

Engineering success

07 May 2008 17:53  [Source: ICB]

Chemical engineering was once a heresy, but it proved its value in the rise of the US chemical industry

Clay Boswell/New York

IN ITS early days, chemical manufacturing was as much a craft as a science, but with the industry's growth in the 1800s and the changing economics of production, there emerged a new kind of professional who could systematically apply both physics and chemistry to practical problems - the chemical engineer.

The concept of chemical engineering was not universally embraced, however. It fell to the US, with its vast reserves of raw materials, giant factories and commercial pragmatism, to nurture the young discipline.

Scale was the catalyst. Until the 19th ­century, making chemicals was a small-scale affair that changed very slowly. There had been advances in the production of sulfuric acid, alkalies and bleaching chemicals, but even these products, like many others, were manufactured in small, family-type establishments, many of them associated with apothecaries. Procedures were empirical, not much different from kitchen recipes.

"For the most part, know-how was passed on from father to son and master to apprentice, without real thought of scientific implications," writes the historian Aaron John Ihde.

By the middle of the 19th century, however, the chemical industry was well on its way to becoming an economic engine. The Leblanc process, discovered in 1791, was the cornerstone of a huge market for sodium carbonate. Sulfuric acid, produced by the lead-chamber process, was in high demand. Driven by the textile industry, these and other inorganics were being produced in large volume.

Organic chemistry was also building momentum. Coal tar was a particularly fertile source of raw materials. Working with one of these materials, aniline, the English chemist William Henry Perkin obtained the first synthetic dye in 1853. This compound, mauveine, gave rise to a booming dye industry, which would branch out into pharmaceuticals, photochemicals, fragrances and other fine chemicals.

SCALING UP

The chemical industry was growing. An expanding middle class wanted more products based on chemistry, and the companies supplying them needed bigger plants to meet demand.

Chemical engineers use ­mathematics, physics and chemistry to design safe, ­efficient processes for the large-scale ­manufacturing of chemicals. One might therefore expect that building large ­chemical plants would require a ­chemical engineer, but in the 19th century, the discipline did not even exist. There was no systematic, generalized body of knowledge concerning the industrialization of ­chemical processes.

It was not until 1887 that an English industrial inspector, George Davis, drew on his broad experience to compile 12 ­lectures, later published, on important chemical processes of the time. His efforts to start a "Society of Chemical Engineers" failed, however. Another 35 years would pass before the British Institution of Chemical Engineers was founded. Cambridge University did not establish a chemical engineering department until after World War II.

Chemical engineering had even less luck in Germany, where combining the study of chemistry and engineering was considered almost unnatural. Instead, mechanical engineers with minimal knowledge of the underlying chemistry designed to the specifications of chemists.

The method worked because German chemical manufacturing focused on dyes and other fine chemicals, according to philosopher and physicist Sunny Auyang.

"These high-tech, high-value products required sophisticated chemistry to design and technical personnel to market," she writes. Dye firms were happy to fund product design, marketing and technical support, but they saw little value in improving the efficiency of the production processes.

Thousands of different dyes were produced, but each in small quantities, typically 100 tons or so.

"For such small volumes, scaling up was rather easy, and could readily be handled by teams of chemists and mechanical engineers," Auyang continues. At large scale, dyes were produced in batches, just as they had been on the bench. Inefficiencies were "easily absorbed in the fat profit margin of high-value products."

In the US, however, chemical engineering quickly found a home. The first "chemical engineering" course was taught at the Massachussetts Institute of Technology (MIT) in 1888. By 1908, the American Institute of Chemical Engineers had been founded. In 1915, an American, Arthur D. Little, introduced the key concept of "unit operations," fundamental activities shared by multiple manufacturing processes, such as crystallization, distillation, catalysis and heat exchange.

Little later defined the purpose of chemical engineering: "Its ultimate objective is so to provide and organize the means for conducting a chemical process that the plant shall operate safely, efficiently, and profitably." Thus charged, chemical engineers made widespread use of innovations such as continuous process technology.

MOTHER NECESSITY

Chemical engineering succeeded in the US because the US chemical industry, which focused on heavy chemicals such as sulfuric acid, chlorine and sodium carbonate, needed it, says Auyang.

"These low-tech, low-value commodities required little, if any, science to design," Auyang points out. "But they were produced in huge volumes. High volumes implied large plants with demanding scaling up. Furthermore, the razor-thin profit margins of these commodities made the smallest waste painful. These industrial characteristics called for efficient production processes, not merely for this or that plant or product, but industry-wide."

The Haber-Bosch process for the production of ammonia, developed at Germany's BASF in the world's first industrial research and development (R&D) facility, was the exception that proved the rule. Most German research was directed toward new chemistry, a priority that was reflected in the academy.

In late 19th and early 20th century Germany, rigid lines separated subjects considered appropriate for university teaching and research from those that were not, and usefulness tended to be a disqualifier, observes Nathan Rosenberg, a technology historian and economist. Aspiring engineers were sent to Technische Hochschulen, which had a "distinctly inferior social status," he notes. Only after World War II were these institutions allowed to call themselves "universities," and they remain solely responsible for the training of engineers.

"This history of the subordination of the engineer to the chemist sheds much light on why Germany's eminence in the science of chemistry failed to give birth to the discipline of chemical engineering," he says.

In the US, however, R&D investment was directed at using existing knowledge. American universities, particularly state universities, happily offered practical degrees and provided an accommodating environment for the development of chemical engineering as a scientific discipline.

"German chemists were better trained than their American counterparts at the turn of the century," says Rosenberg, "but American engineers were better suited for the design and delivery of large-scale chemical plants that offered the prospect of great efficiency improvements."

This early proficiency has profoundly influenced the US chemical industry.

Before the 1920s, petroleum companies and the chemical industry had little to do with one another.

In 1920, however, Standard Oil started the first petrochemical unit, and in the period between World Wars I and II, myriad discoveries were made in the fields of plastics, synthetic fibers and synthetic rubber.

By the end of World War II, coal had been displaced from its position as the key feedstock for organic chemicals, and the US chemical industry, with more than half the world's petroleum production at its disposal - and the toolkit to use it - entered several decades of high growth and profits.

The golden age of petrochemicals is now over, and the 21st century is seeing renewed interest in coal and cellulose, which are now called alternative feedstocks. But so long as safe, efficient and profitable ­manufacturing processes are in demand, chemical engineering will continue to prove its value.

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