Chapter 1: Chemical and Bioengineering PDF

# Chapter 1: Chemical and Bioengineering ## 1.1 Introduction Why did you choose to work toward becoming a chemical or bioengineer? Was it the starting salary? Did you have a role model who was a chemical or bioengineer, or did you live in a community in which engineers were prominent? Or were you...

# Chapter 1: Chemical and Bioengineering ## 1.1 Introduction Why did you choose to work toward becoming a chemical or bioengineer? Was it the starting salary? Did you have a role model who was a chemical or bioengineer, or did you live in a community in which engineers were prominent? Or were you advised that you would do well as a chemical or bioengineer because you were adept at math and chemistry and/or biology? In fact, most prospective engineers choose this field without fully understanding the profession (i.e., what chemical and bioengineers actually do and what they are capable of doing). This brief chapter will attempt to shed some light on this issue. Chemical and bioengineers today hold a unique position at the interface between molecular sciences and macroscopic (large-scale) engineering. They participate in a broad range of technologies in science and engineering projects, involving nanomaterials, semiconductors, and biotechnology. Note that we say "participate" because engineers most often work in multidisciplinary groups, each member contributing his or her own expertise. ## 1.2 A Brief History of Chemical Engineering The chemical engineering profession evolved from the industrial applications of chemistry and separation science (the study of separating components from mixtures), primarily in the refining and chemical industry, which we will refer to here as the chemical process industries (CPI). The first high-volume chemical process was implemented in 1823 in England for the production of soda ash, which was used for the production of glass and soap. During the same time, advances in organic chemistry led to the development of chemical processes for producing synthetic dyes from coal for textiles, starting in the 1850s. In the latter half of the 1800s a number of chemical processes were implemented industrially, primarily in Britain. And in 1887 a series of lectures on chemical engineering which summarized industrial practice in the chemical industry was presented in Britain. These lectures stimulated interest in the United States and to some degree led to the formation of the first chemical engineering curriculum at MIT in 1888. Over the next 10 to 15 years a number of U.S. universities embraced the field of chemical engineering by offering fields of study in this area. In 1908, the American Institute of Chemical Engineers was formed and since then has served to promote and represent the interests of the chemical engineering community. Mechanical engineers understood the mechanical aspects of process operations, including fluid flow and heat transfer, but they did not have a background in chemistry. On the other hand, chemists understood chemistry and its ramifications but lacked the process skills. In addition, neither mechanical engineers nor chemists had backgrounds in separation science, which is critically important to the CPI. In the United States, a few chemistry departments were training process engineers by offering degrees in industrial chemistry, and these served as models for other departments as the demand for process engineers in the CPI began to increase. As industrial chemistry programs grew, they eventually formed separate degree-granting programs as the chemical engineering departments of today. The acceptance of the "horseless carriage," which began commercial production in the 1890s, created a demand for gasoline, which ultimately fueled exploration for oil. In 1901, a Texas geologist and a mining engineer led a drilling operation (the drillers were later to be known as "wildcatters") that brought in the Spindletop Well just south of Beaumont, Texas. At the time, Spindletop produced more oil than all of the other oil wells in the United States. Moreover, a whole generation of wildcatters was born, resulting in a dramatic increase in the domestic production of crude oil, which created a need for larger-scale, more modern approaches to crude refining. As a result, a market developed for engineers who could assist in the design and operation of processing plants for the CPI. The success of oil exploration was to some degree driven by the demand for gasoline for the automobile industry, but ultimately the success of the oil exploration and refining industries led to the widespread availability of automobiles to the general population because of the resulting lower cost of gasoline. These early industrial chemists/chemical engineers had few analytical tools available to them and largely depended upon their physical intuition to perform their jobs as process engineers. Slide rules were used to perform calculations, and by the 1930s and 1940s a number of nomographs were developed to assist them in the design and operation analysis of processes for the CPI. Nomographs are charts that provide a concise and convenient means to represent physical property data (e.g., boiling point temperatures or heat of vaporization) and can also be used to provide simplified solutions of complex equations (e.g., pressure drop for flow in a pipe). The computing resources that became available in the 1960s were the beginnings of the computer-based technology that is commonplace today. For example, since the 1970s computer-aided design (CAD) packages have allowed engineers to design complete processes by specifying only a minimum amount of information; all the tedious and repetitive calculations are done by the computer in an extremely short period of time, allowing the design engineer to focus on the task of developing the best possible process design. During the period 1960 to1980, the CPI also made the transition from an industry based on innovation, in which the profitability of a company depended to a large degree on developing new products and new processing approaches, to a more mature commodity industry, in which the financial success of a company depended on making products using established technology more efficiently, resulting in less expensive products. Globalization of the CPI markets began in the mid-1980s and led to increased competition. At the same time, developments in computer hardware made it possible to apply process automation (advanced process control, or APC, and optimization) more easily and reliably than ever before. These automation projects provided improved product quality while increasing production rates and overall production efficiency with relatively little capital investment. Because of these economic advantages, APC became widely accepted by industry over the next 15 years and remains an important factor for most companies in the CPI. Beginning in the mid-1990s, new areas came on the scene that took advantage of the fundamental skills of chemical engineers, including the microelectronics industry, the pharmaceutical industry, the biotechnology industry, and, more recently, nanotechnology. Clearly, the analytical skills and the process training made chemical engineers ideal contributors to the development of the production operations for these industries. In the 1970s, over 80% of graduating chemical engineers took jobs with the CPI industry and government. By 2000, that number had dropped to 50% because of increases in the number taking jobs with biotechnology companies, pharmaceutical/health care companies, and microelectronics and materials companies. The next section addresses the current distribution of jobs for chemical engineers. ## 1.3 Where Do Chemical and Bioengineers Work? | Year | Chemical, industrial gases, rubber, soaps, fibers, glass, metals, paper | Food, ag products, ag chemical | Energy, petroleum, utilities | Electronics, materials, computers | Environmental, health, and safety | Equipment design and construction | Aerospace, automobile | Research and development | Government | Biotechnology | Pharmaceutical, health care | Professional (including education) | Other | |---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---| | **1996** | 33.3 | 4.5 | 14.1 | 1.4 | 13.8 | 6.4 | 1.1 | 3.9 | 3.6 | 1.5 | 4.2 | 4.7 | 7.4 | | **2000** | 32.5 | 5.1 | 1.9 | 1.9 | 12.6 | 4.7 | 0.9 | 3.8 | 3.6 | 2.2 | 6.5 | 4.5 | 8.6 | | **2002** | 25.2 | 5.6 | 5.1 | 5.1 | 10.6 | 4.4 | 1.8 | 4.4 | 3.5 | 2.4 | 6.1 | 8.6 | 9.6 | | **2005** | 28.1 | 5.7 | 4.5 | 4.5 | 12.6 | 4.2 | 2.0 | 4.2 | 3.7 | 4.4 | 7.0 | 8.4 | - | | **2007** | 25.5 | 5.0 | 3.7 | 3.7 | 14.3 | 3.4 | 2.1 | 3.4 | 3.4 | 3.7 | 7.6 | 7.0 | 1.5 | Table 1.1. lists the percentages of all chemical engineers by employment sector between 1996 and 2007, shows that the percentage of chemical engineers in these developing industries (pharmaceutical, biomedical, and microelectronics industries) increased from 7.1% in 1997 to 19.9% in 2005. Chemical engineers are first and foremost process engineers. That is, chemical engineers are responsible for the design and operation of processes that produce a wide range of products from gasoline to plastics to composite materials to synthetic fabrics to computer chips to corn chips. In addition, chemical engineers work for environmental companies, government agencies including the military, law firms, and banking companies. The trend of chemical engineering graduates taking employment in industries that can be designated as bioengineering is a new feature of the twenty-first century. Not only have separate bioengineering or biomedical departments been established, but some long-standing chemical engineering departments have modified their names to “chemical and bioengineering" to reflect the research and fresh interests of students and faculty. A bioengineer uses engineering expertise to analyze and solve problems in chemistry, biology, and medicine. The bioengineer works with other engineers as well as physicians, nurses, therapists, and technicians. Biomedical engineers may be called upon in a wide range of capacities to bring together knowledge from many technical sources to develop new procedures, or to conduct research needed to solve problems in areas such as drug delivery, body imaging, biochemical processing, innovative fermentation, bioinstrumentation, biomaterials, biomechanics, cellular tissue and genetics, system physiology, and so on. They work in industry, hospitals, universities, and government regulatory agencies. It is difficult to find valid surveys of specific companies or topics to classify bioengineering graduates' ultimate locations, but roughly speaking, one-third of graduates go to medical school, one-third continue on to graduate school, and one-third go to work in industry with a bachelor's degree. ## 1.4 Future Contributions of Chemical and Bioengineering The solution of many of the pressing problems of society for the future (e.g., global warming, clean energy, manned missions to Mars) will depend significantly on chemical and bioengineers. In order to more fully explain the role of chemical and bioengineers and to illustrate the role of chemical and bioengineers in solving society's technical problems, we will now consider some of the issues associated with carbon dioxide capture and sequestration, which is directly related to global warming. Because fossil fuels are less expensive and readily available, we would like to reduce the impact of burning fossil fuels for energy, but without significantly increasing the costs. Therefore, it is imperative that we develop low-cost CO2 capture and sequestration technologies that will allow us to do that. **Figure 1.1. Major sources of carbon dioxide emissions in the United States excluding agriculture.** An examination of Figure 1.1 shows the sources of CO2 emissions in the United States. What category would you attack first? Electric power generation is the number-one source. Transportation sources are widely distributed. No doubt power generation would be the most fruitful. Carbon capture and storage (CCS) is viewed as having promise for a few decades as an interim measure for reducing atmospheric carbon emissions relatively quickly and sharply while allowing conventional coal-fired power plants to last their full life cycles. But the energy costs, the disposal challenges, and the fact that adding CCS to an existing plant actually boosts the overall consumption of fossil fuels (because of the increased consumption of energy to collect and sequester CO2, more power plants have to be built so that the final production of net energy is the same) all suggest that CCS is not an ultimate solution. One interim measure under serious consideration for CCS that might allow existing conventional coal-fired power plants to keep producing until they can be phased out at the end of their full lives involves various known technologies. An existing plant could be retrofitted with an amine scrubber to capture 80% to 95% of CO2 from combustion gases; the CO2 would then be condensed into a liquid that would be transported and stored somewhere indefinitely where it could not leak into the atmosphere. If several hundreds or thousands of CCS systems were deployed globally this century, each capturing 1 to 5 metric tons of CO2 per year collectively, they could contribute between 15% and 55% of the worldwide cumulative mitigation effort. However, the engineering challenges are significant. First, CCS is an energy-intensive process, so power plants require significantly more fuel to generate each kilowatt-hour of electricity produced for consumption. Depending on the type of plant, additional fuel consumption ranges from 11% to 40% more — meaning not only in dollars, but also in additional fossil fuel that would have to be removed from the ground to provide the power for the capture and sequestration, as well as additional CO2 needing sequestration by doing so. Current carbon-separation technology can increase the price tag of producing electricity by as much as 70%. Put another way, it costs about $40 to $55 per ton of carbon dioxide. The annual U.S. output of carbon dioxide is nearly 2 billion tons, which indicates the economic scale of the problem. The U.S. Department of Energy is working on ways to reduce the expenses of separation and capture. By far, the most cost-effective option is partnering CCS not with older plants, but with advanced coal technologies such as integrated-gasification combined-cycle (IGCC) or oxygenated-fuel (oxyfuel) technology. There is also a clear need to maximize overall energy efficiency if CCS itself is not merely going to have the effect of nearly doubling both demand for fossil fuels and the resultant CO2 emitted. Once the CO2 has been captured as a fairly pure stream, the question is what to do with it that is economical. In view of the large quantity of CO2 that must be disposed of, disposal, to be considered a practical strategy, has to be permanent. Any release of gas back into the atmosphere not only would negate the environmental benefits, but it could also be deadly. In large, concentrated quantities, carbon dioxide can cause asphyxiation. Researchers are fairly confident that underground storage will be safe and effective. This technology, known as carbon sequestration, is used by energy firms as an oil-recovery tool. But in recent years, the Department of Energy has broadened its research into sequestration as a way to reduce emissions. And the energy industry has taken early steps toward using sequestration to capture emissions from power plants. Three sequestration technologies are actively being developed: storage in saline aquifers in sandstone formations [refer to S. M. Benson and T. Surles, "Carbon Dioxide Capture and Storage," Proceed. IEEE, 94, 1795 (2006)], where the CO2 is expected to mineralize into carbonates over time; injection into deep, uneconomic coal seams; and injection into depleted or low-producing oil and natural-gas reservoirs. Preliminary tests show that contrary to expectations, only 20% maximum of CO2 precipitates form carbonate minerals, but the majority of the CO2 dissolves in water. Trapping CO2 in minerals would be more secure, but CO2 dissolved in brine is an alternate disposal outcome. Other suggestions for the reduction of CO2 emissions include permanent reduction in demand, chemical reaction, various solvents, use of pure O2 as the oxidant, and so on. See J. Ciferno et al., Chemical Engineering Progress, 33-41 (April, 2009), and F. Princiotta, "Mitigating Global Climate Change through Power-Generation Technology," Chemical Engineering Progress, 24-32 (November, 2007), who have a large list of possible avenues of approach. The bottom line is that a solution for CO2 emissions reduction is not just a matter of solving technical problems but a matter of cost and environmental acceptance. Based on the nature of these challenges, it is easy to see that chemical and bioengineers will be intimately involved in these efforts to find effective solutions. ## 1.5 Conclusion The chemical engineering profession evolved from society's need for products and energy. Today and into the future, chemical and bioengineers will continue to meet society's needs using their process knowledge, their knowledge of fundamental science, and their problem-solving skills.