Providing Global Process Safety Solutions

Runaway Reactions: Ignore the Chemistry at Your Peril

Manufacturing chemicals is a risky business. Chemical producers must be constantly vigilant to the potential for runaway reactions, since manufacturing often requires the use of reactive
chemicals, which may be potentially hazardous. Since chemical reactions involve the transfer of chemical and mechanical energy, proper management of this energy transfer is necessary to
performing manufacturing operations safely without incident or accident.

Safety can be achieved by performing a complete risk assessment founded on process-specific and reaction-specific hazards test data for the desired, and undesired, chemistry and process
operations. For the majority of situations these data can only be obtained from appropriately designed experiments using proper testing techniques. The basis of safety and the window of safe
operations are then derived from the relevant process safety data. The main thrust of this paper is to describe the experimental methodologies for hazards testing and how that allows for
quantitation of the nature and extent of runaway reactions caused by chemical process upsets. Armed with this knowledge chemical manufacturers can make valid risk assessments of their
processes.

Safety is a big issue for both the Occupational Safety Health Administration (OSHA) and the U.S. Environmental Protection Agency (EPA). Both agencies have set regulatory-compliance
standards. OSHA developed standard 1910.119, Process Safety Management (PSM) of Highly Hazardous Chemicals, while EPA developed the “Risk Management Program.” Table 1 lists the
titles of each section, or element, of OSHA’s PSM standard. Of these fourteen elements, six address aspects of the process that require the employer to have reliable and pertinent hazards
data addressing process safety issues.

A central aspect of both these standards is the requirement to perform an appropriately detailed process-hazard analysis (PHA) and remedying the deficiencies, if any, found by the PHA. Most
PHA procedures limit the discussion of the role of chemistry to the properties of the reactant chemicals, the consequences of a release of a reactant or solvent, and the management of the
reaction heat during the reaction. Often, the impact of reactivity of raw materials with each other in unintended ways, interactions with other (unintended) chemicals, and the consequences of such interactions may be only mentioned in passing. Thermodynamic and kinetic information for the desired (synthesis) reaction conditions, for process-upset conditions, and for undesired reaction scenarios, will most probably not be found in the open literature. This is not surprising, given that the majority of chemical manufacture is proprietary. The needed information may not even be available in company files.

View/Download Full Article

July 13, 2015 by David Leggett Category: Articles 0 comments