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Chemical engineering
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Chemical engineers design, construct and operate plants
Chemical engineering is the branch of engineering that deals with the application of physical science (e.g. chemistry and physics), with mathematics, to the process of converting raw materials or chemicals into more useful or valuable forms. In addition to producing useful materials, modern chemical engineering is also concerned with pioneering valuable new materials and techniques - such as nanotechnology, fuel cells and biomedical engineering.[1] A person employed in this field is called a chemical engineer.
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. A related term with a wider definition is chemical technology.
Contents
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1 Chemical engineering timeline
2 Applications
3 Overview
4 Modern chemical engineering
5 Related fields and topics
6 See also
7 References
8 Further reading
9 External links
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[edit] Chemical engineering timeline
Main article: History of chemical engineering
In 1824, French physicist Sadi Carnot, in his “On the Motive Power of Fire”, was the first to study the thermodynamics of combustion reactions in steam engines. In the 1850s, German physicist Rudolf Clausius began to apply the principles developed by Carnot to chemical systems at the atomic to molecular scale.[2] During the years 1873 to 1876 at Yale University, American mathematical physicist Josiah Willard Gibbs, the first to be awarded a Ph.D. in engineering in the U.S., in a series of three papers, developed a mathematical-based, graphical methodology, for the study of chemical systems using the thermodynamics of Clausius. In 1882, German physicist Hermann von Helmholtz, published a founding thermodynamics paper, similar to Gibbs, but with more of an electro-chemical basis, in which he showed that measure of chemical affinity, i.e. the “force” of chemical reactions, is determined by the measure of the free energy of the reaction process. Following these early developments, the new science of chemical engineering began to develop. The following timeline shows some of the key steps in the development of the science of chemical engineering:[3]
1805 – John Dalton published Atomic Weights, allowing chemical equations to be balanced and the basis for chemical engineering mass balances.
1882 – a course in “Chemical Technology” is offered at University College London
1883 – Osborne Reynolds defines the dimensionless group for fluid flow, leading to practical scale-up and understanding of flow, heat and mass transfer
1885 – Henry Edward Armstrong offers a course in “chemical engineering” at Central College (later Imperial College), London.
1888 – There is a Department of Chemical Engineering at Glasgow and West of Scotland Technical College offering day and evening classes[4].
1888 – Lewis M. Norton starts a new curriculum at Massachusetts Institute of Technology (MIT): Course X, Chemical Engineering[5][6]
1889 – Rose Polytechnic Institute awards the first bachelor’s of science in chemical engineering in the US.[7]
1891 – MIT awards a bachelor’s of science in chemical engineering to William Page Bryant and six other candidates.
1892 – A bachelor’s program in chemical engineering is established at the University of Pennsylvania.
1901 – George E. Davis produces the Handbook of Chemical Engineering
1905 – the University of Wisconsin awards the first Ph.D. in chemical engineering to Oliver Patterson Watts.
1908 – the American Institute of Chemical Engineers (AIChE) is founded.
1922 – the UK Institution of Chemical Engineers (IChemE) is founded.
1942 – Hilda Derrick, first female student member of the IChemE.[8]

Applications

Chemical engineering is applied in the manufacture of a wide variety of products. The chemical industry proper manufactures inorganic and organic industrial chemicals, ceramics, fuels and petrochemicals, agrochemicals (fertilizers, insecticides, herbicides), plastics and elastomers, oleochemicals, explosives, detergents and detergent products (soap, shampoo, cleaning fluids), fragrances and flavors, additives, dietary supplements and pharmaceuticals. Closely allied or overlapping disciplines include wood processing, food processing, environmental technology, and the engineering of petroleum, glass, paints and other coatings, inks, sealants and adhesives.
Overview

Chemical engineers design processes to ensure the most economical operation. 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-step, or even 12-step evaporators to reuse the vaporization energy for an economic advantage. In contrast, laboratory chemists evaporate samples in a single step.

The individual processes used by chemical engineers (eg. distillation or filtration) are called unit operations and consist of chemical reactions, 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, laws that apply to discrete parts of equipment, unit operations, or an entire plant. In doing so, chemical engineers must also 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 (see List of Chemical Process Simulators) that can solve mass and energy balances and usually have built-in modules to simulate a variety of common unit operations.

Modern chemical engineering

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, space and military applications. Examples include ultra-strong fibers, fabrics, dye-sensitized solar cells, 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. The line between chemists and chemical engineers is growing ever more thin as more and more chemical engineers begin to start their own innovation using their knowledge of chemistry, physics and mathematics to create, implement and mass produce their ideas.

Related fields and topics

Chemical process modeling is a computer modeling technique used in chemical engineering process design. It typically involves using purpose-built software to define a system of interconnected components, which are then solved so that the steady-state or dynamic behavior of the system can be predicted. The system components and connections are represented as a Process Flow diagram. Simulations can be as simple as the mixing of two substances in a tank, or as complex as an entire alumina refinery.
Chemical process modeling requires a knowledge of the properties of the chemicals involved in the simulation, as well as the physical properties and characteristics of the components of the system, such as tanks, pumps, pipes, pressure vessels, and so on.

Other areas

Basics of Phase Equilibria

Phase equilibria is on of the foundations of the chemical engineering field. This physical state and it's associated calculations can be found in countless spreadsheets, freeware programs, and powerful simulators. At times, it can be easy to forget what is really being calculated with the push of a button.
The vapor pressure of a liquid is defined as the pressure at which the liquid boils at a given temperature. The vapor pressure relations for liquids that can be considered ideal are the well known Antoine and Clausius-Clapeyron equations. Special care should be taken when using these relations for vapor pressure calculations. In particular, there are three cases when they should be avoided. Table 1 below summarizes these three cases.


Table 1: Three Cases to Avoid the Antoine or Clausius-Clapeyron Equations
1. Temperatures outside of the range given for the A,B,C coefficients.
2. Pressures in excess of 10 bar (150 psi)
3. Components that differ in nature. For example, the Antoine Equation introduces significant error in the prediction of the vapor pressure of a propanol-water mixture. However, it can be quite accurate for a isobutane-n-butane mixture.


The limitations of the Antoine Equation are supplemented with a property called fugacity. A detailed discussion of fugacity can be found here at the Resource Page in an article entitled "Validating Your Binary VLE Data". For binary liquids, fugacity is used to calculate the vapor pressure in a spreadsheet entitled "Vapor Pressure of Binary Mixtures" available here.
Fugacity relates vapor pressure and temperature to partial molar volumes and partial molar enthalpies. Since this data is not always available, there was a need to relate experimental data to fugacity and vapor pressure. This was accomplished with binary interaction parameters. You may be familiar with popular thermodynamic models such as NTRL, UNIQUAC, and Wilson. All of these relations relate one component of a mixture to another by the parameters.
The models also offer an effective means of calculating the K-value for a solution. By definition, the K-value is the mole fraction of component j in vapor divided by the mole fraction of component j in liquid, or yj / xj. For ideal mixtures, Dalton's Law allows K to equal the vapor pressure of pure component j divided by the vapor pressure of the solution. Corrections for real thermodynamics include variables such as the fugacity and activity coefficients. All of the models, vapor pressure calculations, and k-value calculations discussed here are well defined and available in many sources.

Now, as a quick review of how to use a TXY diagram:
Let's assume that the above chart is a graph of the phase behavior of a water-methanol solution. The mole fractions of methanol are graphed above. At T1, the vapor will have a methanol mole fraction of y1 and a water mole fraction of 1-y1. At the same temperature, the liquid present will have a mole fraction of methanol being x1 and a mole fraction of water being x1-1.

Chemical Engineer

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Job Profile and Career Information for Chemical Engineers

By Anne Marie Helmenstine, Ph.D., About.com
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Chemical engineers supervise the central pumping station at the Yukos Oil and Gas company in Nefteyugansk, Siberia. Chemical engineers can work anywhere in the world.

Other Links

Process industry trainingFree training animation for the chemical and process industrywww.icheme.org
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Chemical Engineers Jobs Process Engineering Jobs Mechanical Engineers Mechanical Engineering Chemical Engineering Careers

Chemical engineers apply the principles of chemical engineering to identify and solve technical problems. Chemical engineers work mainly within the chemical and petrochemical industries.

What Is a Chemical Engineer?

Chemical engineers use math, physics, and economics to solve practical problems. The difference between chemical engineers and other types of engineers is that they apply a knowledge of chemistry in addition to other engineering disciplines. Chemical engineers may be called 'universal engineers' because their scientific and technical mastery is so extensive.

What Do Chemical Engineers Do?

Some chemical engineers make designs and invent new processes. Some construct instruments and facilities. Some plan and operate facilities. Chemical engineers have helped develop atomic science, polymers, paper, dyes, drugs, plastics, fertilizers, foods, textiles, and chemicals. They devise ways to make products from raw materials and ways to convert one material into another useful form. Chemical engineers can make processes more cost effective or more environmentally friendly or more efficient. A chemical engineer can find a niche in any scientific or engineering field.

Chemical Engineer Employment & Salaries

In 2006, the US Department of Labor estimated there were 30,000 chemical engineers in the United States. At the time of the survey, the average hourly wage for a chemical engineer was $39.23 per hour, ranging from $24.07 to $57.05 per hour. The median annual salary for a chemical engineer was $78,860. The middle 80 percent of chemical engineers made $50,060 to $118,670 annually.
In 2006, the Institution of Chemical Engineers Salary Survey reported the average salary for a chemical engineer in the UK was £53,000, with a starting salary for a graduate averaging £24,000. College graduates with a chemical engineering degree typical gain high salaries even for first employment.

Educational Requirements for Chemical Engineers

An entry-level chemical engineering job typically requires a college bachelor's degree in engineering. Sometimes a bachelor's degree in chemistry or math or another type of engineering will suffice. A master's degree is helpful.

Additional Requirements for Engineers

In the US, engineers who offer their services directly to the public need to be licensed. Licensing requirements vary, but in general an engineer must have a degree from a program that is accredited by the Accreditation Board for Engineering and Technology (ABET), four years of relevant work experience, and must pass a state examination.

Job Outlook for Chemical Engineers

Employment of chemical engineers (as well other types of engineers and chemists) is expected to grow at the average growth rate for all occupations through 2016. The related field of environmental engineering is expected to grow at a much faster rate.
Career Advancement in Chemical Engineering

Entry level chemical engineers advance as they assume more independence and responsibility. As they gain experience, solve problems, and develop designs they may move into supervisory positions or may become technical specialists. Some engineers start their own companies. Some move into sales. Others become team leaders and managers.