Editing Countercurrent exchange (section)

== Countercurrent exchange in industry and scientific research ==
[[Image:Hardendale Lime Works - geograph.org.uk - 73044.jpg|thumb|right|240px|Hardendale Lime Works in the UK using countercurrent kilns to reach high temperatures]]
Countercurrent Chromatography is a method of separation, that is based on the differential partitioning of analytes between two immiscible liquids using countercurrent or cocurrent flow.<ref>{{cite web|title=TheLiquidPhase|url=http://www.theliquidphase.org/|access-date=16 April 2011|url-status=dead|archive-url=https://web.archive.org/web/20080905223925/http://theliquidphase.org/|archive-date=5 September 2008}}</ref> Evolving from Craig's Countercurrent Distribution (CCD), the most widely used term and abbreviation is CounterCurrent Chromatography (CCC),<ref>{{cite web|title=Countercurrent Chromatography|url=http://tigger.uic.edu/~gfp/countercurrent/index2.htm|publisher=University of Illinois at Chicago|access-date=16 April 2011}}</ref> in particular when using hydrodynamic CCC instruments. The term partition chromatography is largely a synonymous and predominantly used for hydrostatic CCC instruments.
* [[Distillation]] of chemicals such as in petroleum refining is done in towers or columns with perforated trays. Vapor from the low boiling fractions bubbles upward through the holes in the trays in contact with the down flowing high boiling fractions. The concentration of low boiling fraction increases in each tray up the tower as it is "stripped". The low boiling fraction is drawn off the top of the tower and the high boiling fraction drawn from the bottom. The process in the trays is a combination of [[heat transfer]] and [[mass transfer]]. Heat is supplied at the bottom, known as a "reboiler" and cooling is done with a condenser at the top.
[[Image:Coflore ACX.png|thumb|left|120px|Counter flow in [[liquid–liquid extraction]]]]
* [[Liquid–liquid extraction]] (also called 'solvent extraction' or 'partitioning') is a common method for extracting a substance from one liquid into another liquid at a different 'phase' (such as "slurry"). This method, which implements a countercurrent mechanism, is used in [[nuclear reprocessing]], [[ore]] processing, the production of fine organic compounds, the processing of [[perfumes]], the production of [[vegetable oil]]s and [[biodiesel]], and other industries.
* [[Gold]] can be separated from a [[cyanide]] solution with the [[Merrill–Crowe process]] using Counter Current Decantation (CCD). In some mines, [[nickel]] and [[cobalt]] are treated with CCD, after the original ore was treated with concentrated [[sulfuric acid]] and steam in [[titanium]] covered [[autoclave]]s, producing nickel cobalt slurry. The nickel and cobalt in the slurry are removed from it almost completely using a CCD system exchanging the cobalt and nickel with [[flash steam]] heated water.

[[File:Countercurrent furnace.svg|thumb|300px|Countercurrent furnace (kiln) heat exchange]]
* [[Lime (substance)|Lime]] can be manufactured in countercurrent [[Metallurgical furnace|furnace]]s allowing the heat to reach high temperatures using low cost, low temperature burning fuel. Historically this was developed by the Japanese in certain types of the [[Anagama kiln]]. The kiln is built in stages, where fresh air coming to the fuel is passed downwards while the smoke and heat is pushed up and out. The heat does not leave the kiln, but is transferred back to the incoming air, and thus slowly builds up to {{Convert|3000|°C|abbr=on}} and more.

[[Image:CemKilnKiln.jpg|thumb|right|220px|Cement counter-current rotary kiln]]
* [[Cement]] may be created using a countercurrent kiln where the heat is passed in the cement and the exhaust combined, while the incoming air draft is passed along the two, absorbing the heat and retaining it inside the furnace, finally reaching high temperatures.
* [[Gasification]]: the process of creating [[methane]] and [[carbon monoxide]] from organic or fossil matter, can be done using a [[Gasification#Counter-current fixed bed ("up draft") gasifier|counter-current fixed bed ("up draft") gasifier]] which is built in a similar way to the Anagama kiln, and must therefore withstand more harsh conditions, but reaches better efficiency.
* In nuclear power plants, water leaving the plant must not contain even trace particles of Uranium. Counter Current Decantation (CCD) is used in some facilities to extract water, totally clear of Uranium.
[[Image:MULTI-STk.jpg|thumb|350px|Exchange current decantation depicted in centrifugal extractors as 1st stage]]
* [[Zippe-type centrifuge]]s use countercurrent multiplication between rising and falling convection currents to reduce the number of stages needed in a cascade.
* Some [[Centrifugal extractor]]s use counter current exchange mechanisms for extracting high rates of the desired material.
* Some [[protein skimmer]]s (devices used to clean saltwater pools and fish ponds of organic matter) use [[protein skimmer#Counter-current flow systems|counter current technologies]].
* Countercurrent processes have also been used to study the behavior of small animals and isolate individuals with altered behaviors due to genetic mutations.<ref>{{cite journal | author = Benzer Seymour | year = 1967 | title = Behavioral Mutants Of Drosophila Isolated By Countercurrent Distribution | url = http://authors.library.caltech.edu/5225/1/BENpnas67.pdf| journal = Proceedings of the National Academy of Sciences USA | volume = 58 | issue = 3| pages = 1112–1119 | doi=10.1073/pnas.58.3.1112| pmid = 16578662 | pmc = 335755 | bibcode = 1967PNAS...58.1112B | doi-access = free }}</ref><ref>{{cite journal | author = Dusenbery David B | year = 1973 | title = Countercurrent separation: A new method for studying behavior of small aquatic organisms | journal = Proceedings of the National Academy of Sciences USA | volume = 70 | issue = 5| pages = 1349–1352 | doi=10.1073/pnas.70.5.1349| pmid = 4514305 | pmc = 433494| bibcode = 1973PNAS...70.1349D | doi-access = free }}</ref><ref>{{cite journal | author = Dusenbery David B., Sheridan Robert E., Russell Richard L. | year = 1975 | title = Chemotaxis-Defective Mutants of the Nematode ''Caenorhabditis elegans'' | journal = Genetics | volume = 80 | issue = 2| pages = 297–309 | doi = 10.1093/genetics/80.2.297 | pmid = 1132687 | pmc = 1213328 }}</ref>