Chemical engineering is the application of science, in particular chemistry, physics and mathematics, to the process of converting raw materials or chemicals into more useful or valuable forms.

Chemical engineering largely involves the design and maintenance of chemical processes for large-scale manufacture. Chemical engineers in this branch are usually employed under the title of process engineer. The development of the large-scale processes characteristic of industrialized economies is a feat of chemical engineering, not chemistry. Indeed, chemical engineers are responsible for the availability of the modern high-quality materials that are essential for running an industrial economy.

Examples

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Following is an example that illustrates the process engineering part of chemical engineering:

The difference between chemical engineering and chemistry can be illustrated by considering the example of producing orange juice. A chemist working in the laboratory investigates and discovers a multitude of pathways to extract the juice of an orange. The simplest mechanism found is to cut the orange in half and squeeze the orange using a manual juicer. A more complicated approach found is to peel and then crush the orange and collect the juice. A company then commissions a chemical engineer to design a plant to manufacture several thousand tons of orange juice per year. The chemical engineer investigates all the available methods for making orange juice and evaluates them according to their economical viability. Even though the manual juicing method is simple, it is not economical to employ thousands of people to manually juice oranges. Thus another, cheaper method is used (possibly the 'peel and crush' technique). The easiest method of manufacture on a laboratory bench will not necessarily be the most economical method for a manufacturing plant.

A prototypic example of the development of chemical engineering as a science is the Haber-Bosch process, which involves remarkably simple chemistry, but required extensive chemical engineering research to develop.

Overview

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Chemical engineers are aiming for the most economical process. This means that the entire production chain must be planned and controlled for costs. A chemical engineer can both simplify and complicate "showcase" reactions for an economic advantage. Using a higher pressure or temperature makes several reactions easier; ammonia, for example, is simply produced from its component elements in a high-pressure reactor. On the other hand, reactions with a low yield can be recycled continuously, which would be complex, arduous work if done by hand in the laboratory. It is not unusual to build 6-, or even 12-step evaporators to reuse the vaporization energy for an economic advantage. In contrast, laboratory chemists evaporate samples in a single step, wasting the energy.

The individual processes used by chemical engineers (eg. distillation or filtration) are called unit operations and consist of chemical reaction, mass-, heat- and momentum- transfer operations. Unit operations are grouped together in various configurations for the purpose of chemical synthesis and/or chemical separation. Some processes are a combination of intertwined transport and separation unit operations, (e.g. reactive distillation).

Three primary physical laws underlying chemical engineering design are Conservation of mass, Conservation of momentum and Conservation of energy. The movement of mass and energy around a chemical process are evaluated using Mass balances and energy balances which apply these laws to whole plants, unit operations or discrete parts of equipment. In doing so, Chemical Engineers use principles of thermodynamics, reaction kinetics and transport phenomena. The task of performing these balances is now aided by process simulators, which are complex software models (such as Aspen Plus, Pro II and Hysys) that can solve mass and energy balances and usually have built-in modules to simulate a variety of common unit operations.

Modern chemical engineering

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The modern discipline of chemical engineering encompasses much more than just process engineering. Chemical engineers are now engaged in the development and production of a diverse range of products, as well as in commodity and specialty chemicals. These products include high performance materials needed for aerospace, automotive, biomedical, electronic, environmental and military applications. Examples include ultra-strong fibers, fabrics, adhesives and composites for vehicles, bio-compatible materials for implants and prosthetics, gels for medical applications, pharmaceuticals, and films with special dielectric, optical or spectroscopic properties for opto-electronic devices. Additionally, chemical engineering is often intertwined with biology and biomedical engineering. Many chemical engineers work on biological projects such as understanding biopolymers (proteins) and mapping the human genome.

Related fields and topics

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Today, the field of chemical engineering is a diverse one, covering areas from biotechnology and nanotechnology to mineral processing.

• Biochemical engineering
• Biomedical engineering
• Biotechnology
• Ceramics
• Natural environment
• Fluid dynamics
• Heat transfer
• Mass transfer
• Materials science
• Microfluidics
• Nanotechnology
• Chemical reactor
• Separation processes (see also: separation of mixture)
  • Membrane processes
  • Distillation processes
  • Crystallization processes
• Thermodynamics
• Polymers
• Process control
• Process design
• Chemical process modeling
• Pulp and paper

See also

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• History of chemical engineering
• List of chemical engineering topics
• List of chemical engineers

External links

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• American Institute of Chemical Engineers (USA)
• Institution of Chemical Engineers (UK)
• Canadian Society for Chemical Engineers
• Engineers Australia (AUS)
• Chemical Engineering sites (dmoz Open Directory Project)
• Chemical Engineering software (dmoz Open Directory Project)
• Job Search For Chemical Engineers

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