The use of a single chemical or refinery process unit alternately in more than one operation; for example, a catalytic reactor will first produce a chemical product and then will be blocked from the main process stream during catalyst regeneration.



Related Terms

BATCH

  1. The quantity of material required for or produced by one operation. 2. An amount of material subjected to some unit chemical process or physical mixing process to make the final product substantially uniform.

BLOWDOWN STACK

A vertical stack or chimney into which the contents of a chemical or petroleum process unit are emptied in case of an operational emergency.

FIREDAMP REFORMING PROCESS

A process in which methane (firedamp) is mixed with steam and passed over a nickel catalyst for conversion to a mixture of hydrogen and carbon monoxide; this mixture is blended with pure methane, and the result is a fuel of high calorific value.

DIFFUSIVITY

The quantity of heat passing normally through a unit area per unit time divided by the product of specific heat, density, and temperature gradient. Also known as thermal diffusivity; thermometric conductivity.

DIGESTION

  1. Preferential dissolving of mineral constituents in concentrations of ore. 2. Liquefaction of organic waste materials by action of microbes. 3. Separation of fabric from tires by the use of hot sodium hydroxide. 4. Removing lignin from wood in manufacture of chemical cellulose paper pulp. 5. The process of sewage treatment by the anaerobic decomposition of organic matter.

CHLORALKALI PROCESS

An industrial chemical process based on the electrolysis of sodium chloride for the production of sodium hydroxide and chlorine.

ACID CLEANING

The process of cleaning the interior surfaces of steam-generating units by filling the unit with a dilute acid accompanied by an inhibitor to prevent corrosion and by subsequently draining, washing, and neutralizing the acid by a further wash of alkaline water.

GROUT PIPE

  1. A pipe that transports grout 257 gudgeon Guggenheim process Guggenheim process 2. A method of chemical precipitation which employs ferric chloride and aeration to prepare sludge for filtration.

ACID PROCESS

A chemical pulping process that uses an acidic calcium sulphite solution plus heat to break the bonds in wood between the cellulose and the wood fibres.

COUNTING CIRCUIT. COUNTERCURRENT EXTRACTION

A liquid-liquid extraction process in which the solvent and the process stream in contact with each other flow in opposite directions. Also known as countercurrent separation.

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