Chemical engineering
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2008-07-16T01:35:18Z
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[[Image:Colonne distillazione.jpg|thumb|right|250px|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 [[material]]s or [[chemical]]s into more useful or valuable forms. In addition to producing useful materials, chemical engineering is also concerned with pioneering valuable new materials and techniques, an important form of [[research and development]]. 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'''. 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.
==Chemical Engineering Timeline==
{{main|History of chemical engineering}}
In 1824, French physicist [[Nicolas Léonard Sadi Carnot|Sadi Carnot]], in his “On the Motive Power of Fire”, was the first to study the [[thermodynamics]] of [[combustion reaction]]s in [[steam engine]]s. In the 1850s, German physicist [[Rudolf Clausius]] began to apply the principles developed by Carnot to chemicals systems at the atomic to molecular scale.<ref>Mechanical Theory of Heat – Nine Memoirs on the development of concept of "Entropy" by Rudolf Clausius [1850-1865]</ref> 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 system]]s 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 reaction]]s, is determined by the measure of the [[Thermodynamic free energy|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:<ref>[http://www.che.ncsu.edu/history/HistoryoftheChEDepartment.pdf History of Chemical Engineering] – at North Carolina State University (and in general).</ref>
*'''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<ref>''Glasgow Herald'' July 18, 1888 and September 5, 1888</ref>.
*'''1888''' – [[Lewis M. Norton]] starts a new curriculum at [[Massachusetts Institute of Technology]] (MIT): Course X, Chemical Engineering<ref>N. A. Peppas (1989) ''One Hundred Years of Chemical Engineering'' Kluwer ISBN 0792301455</ref>
*'''1889''' – [[Rose-Hulman Institute of Technology|Rose Polytechnic Institute]] awards the first bachelor’s of science in chemical engineering in the US.<ref>[http://www.in.gov/iedc/files/Life_Sciences_Report.pdf 2007 Indiana Economic Development Corporation Life Sciences Report]</ref>
*'''1891''' – [[Massachusetts Institute of Technology|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–Madison|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.<ref>Colin Duvall and Sean F, Johnston ''Scaling Up: The Institution of Chemical Engineers and the Rise of a New Profession'' Kluwer Academic Publishers (2000)</ref>
== 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 [[elastomer]]s, 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.
== Example ==
To show the difference between laboratory chemistry and industrial chemical engineering, consider a simple one-step reaction between two reagents R1 and R2 to give a product P and waste W. The reaction may be represented R1 + R2 = P + W. A [[solvent]] S and possibly a [[catalyst]] C may be required, and it may need to be heated to speed the reaction.
A specific example would be the synthesis of [[aspirin]] by the reaction of [[salicylic acid]] (R1) with [[acetic anhydride]] (R2) in solvent water (S) and in the presence of catalyst [[phosphoric acid]] (C). Aspirin is the product P, and acetic acid (W) is also formed.
In the laboratory 5 grams of R1 (a solid) are added to 120 ml of water in a flask. 5 ml of R2 (a liquid) are added plus 0.5 ml of phosphoric acid solution, and the flask is heated in a water bath. The contents are agitated by swirling the flask or with a laboratory stirrer and heated under reflux for about an hour.
The material is allowed to cool down and crystals of aspirin are formed, which may be filtered off, and perhaps recrystallized. A good yield would be 5 to 6 grams. The remaining solution is poured down the sink.
Now consider an industrial process in which we replace grams with tons.
Firstly suitable storage (say for two weeks of production) must be provided for the raw materials. In this case R1 is a solid and would be put in a [[storage silo]]; R2 is a corrosive liquid, combustible and sensitive to water, so would need a closed tank of resistant material. A means of transport to the reactor must be provided, such as a [[screw conveyor]] for the solid R1 and a [[pump]] and pipes for liquid R2. Chemical engineers would calculate the sizes and power requirements and specify suitable materials.
Similar arrangements must be made for the solvent S and the catalyst C. In this case, water is the solvent, but ordinary tap water would not be good enough, so there will be a separate process to clean the water.
The reactor is now to contain 120 tons of water and the other ingredients so cannot be swirled. An agitator must be designed and its power consumption calculated to give the necessary mixing. Heating and cooling are considered free in the laboratory, but not in industry. The chemical engineers must first calculate the amount of heat to be added and removed, and then design suitable methods to do this, perhaps by passing steam through an outer jacket of the vessel to heat. They will probably decide to pump the reacted mixture to another vessel with a cooler, then to a filter. The solid will then go to further equipment to dissolve, crystallize and filter again, giving perhaps 5.5 tons of aspirin, which will be dried and placed in suitable storage, which must also be designed. (The drying process uses significant amounts of energy.)
However, there is about 125 tons of waste which cannot be just poured down the drain. It will contain some unreacted R1 and about 3 tons of W, which must be recovered and recycled. (In this case, W can be converted to R2 in another reactor.) The catalyst may be recovered, or made harmless by a chemical reaction before disposal. Thus there will be another set of equipment to save the cost of wasting chemicals and to protect the environment. Solvents other than water are generally recycled by [[distillation]], but water is also re-used and recycled as far as economically feasible.
This process may run as a batch process, where reactors are filled and emptied discharging their contents through the plant upon completion. Alternatively the process may be run as a continuous process, where the reaction precursors are fed through the plant at a fixed rate. The choice of continuous or batch is dependent upon a combination of [[reaction kinetics]], the desired amount of product and the economics of the plant's operation and would be decided during the design phase of the plant.
== 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 operation]]s and consist of [[chemical reaction]]s, [[mass transfer|mass-]], [[heat transfer|heat-]] and [[fluid dynamics|momentum-]] transfer operations. Unit operations are grouped together in various configurations for the purpose of [[chemical synthesis]] and/or [[separation of mixture|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]], [[Momentum|conservation of momentum]] and [[conservation of energy]]. The movement of mass and energy around a chemical process are evaluated using [[mass balance]]s and [[energy balance]]s, 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 [[chemical]]s. These products include high performance materials needed for [[aerospace]], [[automotive engineering|automotive]], [[biomedical engineering|biomedical]], [[electronics|electronic]], [[environmental engineering|environmental]] and space and [[military]] applications. Examples include ultra-strong fibers, [[Cloth|fabrics]], [[adhesives]] and composites for vehicles, [[Biocompatibility|bio-compatible materials]] for implants and [[prosthetics]], [[gel]]s for medical applications, [[pharmaceuticals]], and films with special [[dielectric]], optical or [[spectroscopy|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 [[human genome project|mapping the human genome]].
==Related fields and topics==
Today, the field of chemical engineering is a diverse one, covering areas from [[biotechnology]] and [[nanotechnology]] to [[mineral processing]].
{{col-begin}}
{{col-break}}
*[[Biochemical engineering]]
*[[Biomedical engineering]]
*[[Biomolecular engineering]]
*[[Biotechnology]]
*[[Ceramic]]s
*[[Chemical process modeling]]
*[[Chemical Technologist]]
*[[Chemical reactor]]
*[[Computational fluid dynamics]]
*[[Distillation Design]]
*[[Electrochemistry]]
*[[Environmental engineering]]
{{col-break}}
*[[Fluid dynamics]]
*[[Food process engineering]]
*[[Heat transfer]]
*[[Mass transfer]]
*[[Materials science]]
*[[Microfluidics]]
*[[Mineral Processing]]
*[[Nanotechnology]]
*[[Natural environment]]
*[[Plastics Engineering]]
*[[Polymer]]s
*[[Process control]]
{{col-break}}
*[[Process design (chemical engineering)|Process design ]]
*[[Process development]]
*[[Pulp and paper]]
*[[Semiconductor device fabrication]]
*[[Separation process]]es (see also: [[separation of mixture]])
**[[Crystallization processes]]
**[[Distillation|Distillation processes]]
**[[Membrane processes (chemistry)|Membrane processes]]
*[[Textile engineering]]
*[[Thermodynamics]]
*[[Transport Phenomena]]
*[[Unit operations]]
*[[Unit Operations of Chemical Engineering]]
{{col-end}}
== See also ==
{{Portalpar|Chemistry|Nuvola apps edu science.png}}
{{Portal|Engineering}}
* [[American Institute of Chemical Engineers]] (AIChE)
* [[Chemical engineer]]
* [[Food and Bioprocess Technology]]
* [[Contemporary Food Engineering]]
* [[Education for Chemical Engineers]]
* [[List of chemical engineers|List of notable chemical engineers]]
* [[List of chemical engineering societies]]
* [[Process design (chemical engineering)]]
* [[List of Chemical Process Simulators]]
==References==
{{reflist}}
==Further reading==
*{{cite book|author=Kister, Henry Z.|title=[[Distillation Design]]|edition=1st Edition |publisher=McGraw-Hill|year=1992|id=ISBN 0-07-034909-6}}
*{{cite book|author=Green, Don W. and Perry, Robert H. (deceased)|title=[[Perry's Chemical Engineers' Handbook]]|edition=7th Edition| publisher=McGraw-Hill|year=1997|id=ISBN 0-07-049841-5}}
*{{cite book|author=Bird, R.B., Stewart, W.E. and Lightfoot, E.N.|title=[[Transport Phenomena]]|edition=Second Edition|publisher=John Wiley & Sons|year=August 2001|id=ISBN 0-471-41077-2}}
*{{cite book| author=McCabe, W., Smith, J. and Harriott, P.|edition=7th Edition|title=[[Unit Operations of Chemical Engineering]]|publisher=McGraw Hill|location=|year=2004|id=ISBN 0-07-284823-5}}
*{{cite book|author= Seader, J. D., and Henley, Ernest J.|title=Separation Process Principles|publisher=Wiley| location=New York|year=1998|id=ISBN 0-471-58626-9}}
* {{cite book|author=Chopey, Nicholas P.|title=Handbook of Chemical Engineering Calculations|edition=3rdEdition|publisher=McGraw-Hill|year=2004|id=ISBN 0071362622}}
*{{cite book|author=Himmelbau, David M.|title=Basic Principles and Calculations in Chemical Engineering|edition=6th Edition|publisher=Prentice-Hall|year=1996|id=ISBN 0133057984}}
*{{cite book| author=Editors: Jacqueline I. Kroschwitz and Arza Seidel|edition=5th Edition|title=Kirk-Othmer Encyclopedia of Chemical Technology|publisher=Wiley-Interscience|location=Hoboken, NJ|year=2004|id=ISBN 0-471-48810-0}}
*{{cite book|author=King, C.J.|2nd Edition|title=Separation Processes|publisher=McGraw Hill|year=1980|id=ISBN 0-07-034612-7}}
*{{cite book|author=Coulson J. M. ; Richardson J. F. ; Backhurst J. R. ; Harker J. H.|2nd Edition|title=Chemical engineering. Volume 2 : Particle technology and separation processes|publisher=Pergamon Press - New York |year= 1991|id=xxvi+968pp}}
*[[Octave Levenspiel|Levenspiel, O.]]: The Chemical Reactor Omnibook, Osu, Oregon, 1993
==External links==
*[http://www.cache.org Computer Aids for Chemical Engineering Education (CACHE)]
*[http://www.tcetoday.com/tce/mainframe.htm The Chemical Engineer]
*[http://www.cheresources.com/indexzz.shtml Chemical Engineers' Resource Page]
*[http://www.aiche.org/ American Institute of Chemical Engineers (USA)]
*[http://www.icheme.org Institution of Chemical Engineers (UK)]
*[http://www.cheminst.ca/csche_home__e.htm Canadian Society for Chemical Engineers]
*[http://www.iiche.org.in/ Indian Institute of Chemical Engineers (IN)]
*[http://www.abeq.org.br/ Brazilian Association of Chemical Engineering (BRA)]
*[http://www.kimyamuhendisi.com/ Chemical Engineering Informations -Turkey (TR)]
*{{dmoz|Business/Chemicals/Engineering/|Chemical Engineering (businesses)}}
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