Chemical process

  • chemical process
  • The particular method of manufacturing or making a chemical usually involving a number of steps or operations.
Abstract from DBPedia
    In a scientific sense, a chemical process is a method or means of somehow changing one or more chemicals or chemical compounds. Such a chemical process can occur by itself or be caused by an outside force, and involves a chemical reaction of some sort. In an "engineering" sense, a chemical process is a method intended to be used in manufacturing or on an industrial scale (see Industrial process) to change the composition of chemical(s) or material(s), usually using technology similar or related to that used in chemical plants or the chemical industry. Neither of these definitions are exact in the sense that one can always tell definitively what is a chemical process and what is not; they are practical definitions. There is also significant overlap in these two definition variations. Because of the inexactness of the definition, chemists and other scientists use the term "chemical process" only in a general sense or in the engineering sense. However, in the "process (engineering)" sense, the term "chemical process" is used extensively. The rest of the article will cover the engineering type of chemical processes. Although this type of chemical process may sometimes involve only one step, often multiple steps, referred to as unit operations, are involved. In a plant, each of the unit operations commonly occur in individual vessels or sections of the plant called units. Often, one or more chemical reactions are involved, but other ways of changing chemical (or material) composition may be used, such as mixing or separation processes. The process steps may be sequential in time or sequential in space along a stream of flowing or moving material; see Chemical plant. For a given amount of a feed (input) material or product (output) material, an expected amount of material can be determined at key steps in the process from empirical data and material balance calculations. These amounts can be scaled up or down to suit the desired capacity or operation of a particular chemical plant built for such a process. More than one chemical plant may use the same chemical process, each plant perhaps at differently scaled capacities. Chemical processes like distillation and crystallization go back to alchemy in Alexandria, Egypt. Such chemical processes can be illustrated generally as block flow diagrams or in more detail as process flow diagrams. Block flow diagrams show the units as blocks and the streams flowing between them as connecting lines with arrowheads to show direction of flow. In addition to chemical plants for producing chemicals, chemical processes with similar technology and equipment are also used in oil refining and other refineries, natural gas processing, polymer and pharmaceutical manufacturing, food processing, and water and wastewater treatment.

    ケミカルプロセス(en:chemical process)の用語は、科学的な意味では1つまたは複数の化学物質または化合物を何らかの形で変更する方法または手段。そうした化学のプロセスはそれ自体で起こることも、外力によって引き起こされることもあり、ある種の化学反応を伴う。これを 「エンジニアリング 」のセンス、化学プロセス手法での製造課程を (参照又は工業規模工業プロセスを類似または関連する技術を利用して、化学物質の組成物又は材料(複数可)を変更して)化学プラントや化学工業で利用している。