"In mathematics, the Euclidean algorithm, or Euclid's algorithm, is a method for computing the greatest common divisor (GCD) of two (usually positive) integers, also known as the greatest common factor (GCF) or highest common factor (HCF). ...
The GCD of two positive integers is the largest integer that divides both of them without leaving a remainder (the GCD of two integers in general is defined in a more subtle way).
In its simplest form, Euclid's algorithm starts with a pair of positive integers, and forms a new pair that consists of the smaller number and the difference between the larger and smaller numbers. The process repeats until the numbers in the pair are equal. That number then is the greatest common divisor of the original pair of integers.
The main principle is that the GCD does not change if the smaller number is subtracted from the larger number. ... Since the larger of the two numbers is reduced, repeating this process gives successively smaller numbers, so this repetition will necessarily stop sooner or later - when the numbers are equal (if the process is attempted once more, one of the numbers will become 0)." [Euclidean algorithm. Wikipedia]
The flowchart example "Euclidean algorithm" was created using the ConceptDraw PRO diagramming and vector drawing software extended with the Mathematics solution from the Science and Education area of ConceptDraw Solution Park.

"A process flow diagram (PFD) is a diagram commonly used in chemical and process engineering to indicate the general flow of plant processes and equipment. The PFD displays the relationship between major equipment of a plant facility and does not show minor details such as piping details and designations. Another commonly used term for a PFD is a flowsheet. ...
Process flow diagrams of multiple process units within a large industrial plant will usually contain less detail and may be called block flow diagrams or schematic flow diagrams." [Process flow diagram. Wikipedia]
The process flow diagram (PFD) template for the ConceptDraw PRO diagramming and vector drawing software is included in the Chemical and Process Engineering solution from the Engineering area of ConceptDraw Solution Park.

This process flow diagram (PFD) example shows an amine treating system for the removal of gaseous hydrogen sulfide from gas streams. It is used in oil refineries and chemical plants. This PFD sample was redesigned from the Wikimedia Commons file: AmineTreating.png. [commons.wikimedia.org/ wiki/ File:AmineTreating.png]
This file is licensed under the Creative Commons Attribution-Share Alike 3.0 Unported license. [creativecommons.org/ licenses/ by-sa/ 3.0/ deed.en]
"Amine gas treating, also known as gas sweetening and acid gas removal, refers to a group of processes that use aqueous solutions of various alkylamines (commonly referred to simply as amines) to remove hydrogen sulfide (H2S) and carbon dioxide (CO2) from gases. It is a common unit process used in refineries, and is also used in petrochemical plants, natural gas processing plants and other industries.
Processes within oil refineries or chemical processing plants that remove hydrogen sulfide are referred to as "sweetening" processes because the odor of the processed products is improved by the absence of hydrogen sulfide. An alternative to the use of amines involves membrane technology. Membranes are attractive since no reagents are consumed.
Many different amines are used in gas treating:
Diethanolamine (DEA),
Monoethanolamine (MEA),
Methyldiethanolamine (MDEA),
Diisopropanolamine (DIPA),
Aminoethoxyethanol (Diglycolamine) (DGA).
The most commonly used amines in industrial plants are the alkanolamines DEA, MEA, and MDEA. These amines are also used in many oil refineries to remove sour gases from liquid hydrocarbons such as liquified petroleum gas (LPG)." [Amine gas treating. Wikipedia]
The PFD example "Amine treating unit schematic diagram" was drawn using the ConceptDraw PRO diagramming and vector drawing software extended with the Chemical and Process Engineering solution from the Chemical and Process Engineering area of ConceptDraw Solution Park.