Runaway reactions

Chemical engineering[ edit ] Thermal runaway is also called thermal explosion in chemical engineeringor runaway reaction in organic chemistry. It is a process by which an exothermic reaction goes out of control:

Runaway reactions

EPA is striving to learn the causes and contributing factors associated with chemical accidents to prevent their recurrence. Major chemical accidents cannot be prevented solely through command and control regulatory requirements, but by understanding the fundamental root causes, widely disseminating the lessons learned, and integrating them into safe operations.

Many industrial chemical processes involve exothermic heat generating reactions.

IChemE | Safety and Loss Prevention Special Interest Group | Hazards archive | Runaway reactions

Uncontrolled, or runaway, reactions can occur as a result of various situations, such as mischarged raw materials, failure of a reactor's cooling system or the presence of contaminants.

If the heat generation exceeds the reactor's ability to remove it, the reaction can accelerate - or run away - and cause the temperature and pressure to increase.

A sudden energy release from such an uncontrolled reaction has the potential to harm workers, the public, and the environment. The following Case Study aims to increase awareness of possible hazards connected with exothermic reactions.

Three Runaway reactions fighters were injured during the response, treated for first-degree chemical burns, and released. The blast was reported to be felt at least 2 miles and possibly as far as 7 miles away according to various news accounts and other reports.

Runaway reactions

As a result of the explosion, one worker was killed and four others injured. The explosion extensively damaged the plant.

The purpose of this effort was to understand the circumstances associated with the accident to prevent a recurrence at this and other facilities.

The reaction of phenol or substituted phenol with an aldehyde, such as formaldehyde, in the presence of an acidic or basic catalyst is used to prepare phenolic resins.

Phenolic resins are used in adhesives, coatings, and molding compounds. The type of catalyst used, the ratio of reactants, and the reaction conditions determine the molecular structure and physical properties of the resin produced.

Typically, phenol-formaldehyde reactions are highly exothermic and sensitive to a variety of physical and chemical conditions. Once a reaction is initiated, heat generated by the reaction increases the reaction rate generating more heat.

Because the reaction rate is typically an exponential function of temperature, the rate of heat generation will accelerate. Without intervention, a thermal runaway will occur, producing a large amount of heat in a very short time. If the reaction continues to accelerate, the pressure buildup may reach and exceed the ultimate strength of the reactor and cause it to explode.

The heat of reaction is removed by the evaporation of water or other liquid from the process, condensation of the liquid in the overhead condensation system, and return of the liquid to the reactor vessel.

Emergency relief on the reactor is usually provided by rupture disks. In a conventional novalak process, molten phenol is placed into the reactor, followed by a precise amount of acid catalyst.

The formaldehyde solution is then added. For safety reasons, slow continuous or stepwise addition of formaldehyde is preferred over adding the entire charge at once Kirk-Othmer, p. The manufacture of phenolic resins has resulted in a number of accidents dating back to A search of accident databases and the literature reveals that numerous incidents have resulted in worker fatalities and injuries and significant property damage.

Table 1 is a summary of the incidents that have occurred during the past 10 years. Pressure buildup during manufacture of phenolic resin, pressure increased, rupture disks popped.

Product was released through emergency vent. The cause of accident was reported as failure to open condensate return line.

Safety & Loss Prevention Special Interest Group

A 13, gallon reactor exploded during production of a phenol-formaldehyde resin. Explosion occurred during initial stages of catalyst addition. Temperature increased in chemical reactor, releasing phenol formaldehyde resin. Manufacture of phenolic resins and thermoset plastics; release of phenol and formaldehyde from process vessel.Before you can handle chemical reactions safetly, you must first understand them.

to runaway and with a view to highlighting particular areas for attention by those, particularly chemists, chemical engineers and managers, who research, devise, design or operate existing, new or modified products, processes, plant Runaway Reactions in Batch Reactors. Runaway Reactions Reactive chemical hazards can lead to runaway reactions with a catastrophic consequence. The hazards in such system are seldom the characteristics of the chemical by itself but are highly dependent on the process conditions and modes of operations. How to Prevent Runaway Reactions August Phenol-formaldehyde reactions are common industrial processes. The reaction of phenol or substituted phenol with an aldehyde, such as formaldehyde, in the presence of an acidic or basic catalyst is used to prepare phenolic resins.

In this course, you'll identify potential runaway reactions and tools for sizing relief systems to safely control and contain them. How to Prevent Runaway Reactions August Phenol-formaldehyde reactions are common industrial processes.

Runaway reactions

The reaction of phenol or substituted phenol with an aldehyde, such as formaldehyde, in the presence of an acidic or basic catalyst is used to prepare phenolic resins. Runaway Reactions (Published as IChemE Symposium series no. 68) A General Approach to the Prediction and Control of Potential Runaway Reaction.

A runaway reaction is frequently going to the worst case contingency when sizing the relief devices for your reactor systems. The problem is, these are extremely involved calculations that require specialized data, and chemical engineering and modeling expertise.

Runaway Reactions (Published as IChemE Symposium series no. 68) A General Approach to the Prediction and Control of Potential Runaway Reaction. Runaway Reactions Reactive chemical hazards can lead to runaway reactions with a catastrophic consequence.

The hazards in such system are seldom the characteristics of the chemical by itself but are highly dependent on the process conditions and modes of operations.

Process Safety Series: Runaway Reactions