Designing and operating safe chemical reaction processes HSG143

Health and SafetyExecutiveGlossaryAccelerating rate calorimeter (ARCTM): A type of adiabatic calorimeter.Accumulation: A build-up of unreacted materials in a semi-batch or continuousreactor.Adiabatic: No heat transfer occurs to or from the environment surrounding thesample, including the sample container.Adiabatic temperature rise: The increase in temperature of a reacting mixture asa result of exothermic chemical reaction, when there is no heat transfer to or fromthe environment.ARC TM : see accelerating rate calorimeter.Autocatalysis: The increase of the rate of reaction due to the catalysing effect ofthe reaction products.Autoignition temperature: The minimum temperature at which a material willignite spontaneously under specified test conditions. It can also be referred to asthe minimum ignition temperature.Basis of safety: The combination of measures relied upon to ensure safety. Thebasis of safety for a reactor highlights those aspects of the design and operation(hardware, protective systems and procedures) that are safety critical. The basis ofsafety can only be selected once all the significant hazards have been identifiedand evaluated.Batch process: An operation in which all the reactants including any solvent areadded to a reactor at the start of a reaction.Batch reactor: Reactor in which all reactants and solvents are introduced beforesetting the reaction conditions. Products are only taken from the reactor uponconclusion of the reaction process.Bubbly flow: A two-phase flow regime in which small discrete bubbles existwithin a liquid.Calorimeter: See reaction calorimeter.Choked flow: The maximum flow rate of a compressible fluid (gas or two-phase)for a given upstream pressure.Churn-turbulent flow: A two-phase flow regime in which large bubbles existwithin a liquid.Continuous reactors: Reactors that are characterised by a continuous flow ofreactants into, and products from, the reactor system.Continuous stirred tank reactor (CSTR): A tank reactor in which the contentsare stirred by an agitator to promote mixing and characterised by a continuous flowof reactants into, and products from, the reaction system.Designing and operating safe chemical reaction processes Page 60 of 64