Runaway Reactions
Introduction
The primary production processes to produce active drugs involves a wide variety of complex reactions and reaction sequences, where raw materials react together to give the product. Such chemical process often releases energy, in the form of heat, and the reaction is described as exothermic. Many of these reactions may also evolve gases at high rates, and could cause reactor over-pressure.
Thermal runaway reaction
Runaway reactions are thermally unstable reactions where the heat of reaction can raise the temperature of the reactants sufficiently to accelerate the reaction rate out of control. The temperature at which the runaway starts is often termed the onset temperature.
A reaction thermal runaway begins when the heat produced by the reaction exceeds the heat removed. The temperature rises, the reaction rate increases causing a further increase in the rate of the heat generation. The temperature rise can be very rapid leaving a limited time for correction.
Such reactions are normally controlled by cooling the reactor or by controlling the addition of the reactants. Loss of reactor cooling or agitation during the course of an exothermic reaction are two of the commonest causes of runaway reactions. A runaway reaction can cause the reactor contents to boil, generate vapor or explode, and over-pressurize the reactor, which can also be followed by release of toxic or flammable gases.
Effects of thermal runaway
A runaway exothermic reaction can have a range of results from the boiling over of the reaction mass, to large increases in temperature and pressure that lead to an explosion. Such violence can cause blast and missile damage. If flammable materials are released, fire or a secondary explosion may result. Hot liquors and toxic materials may contaminate the workplace or generate a toxic cloud that may spread off-site.
There can be serious risk of injuries, even death, to plant operators, and the general public and the local environment
The primary production processes to produce active drugs involves a wide variety of complex reactions and reaction sequences, where raw materials react together to give the product. Such chemical process often releases energy, in the form of heat, and the reaction is described as exothermic. Many of these reactions may also evolve gases at high rates, and could cause reactor over-pressure.
Thermal runaway reaction
Runaway reactions are thermally unstable reactions where the heat of reaction can raise the temperature of the reactants sufficiently to accelerate the reaction rate out of control. The temperature at which the runaway starts is often termed the onset temperature.
A reaction thermal runaway begins when the heat produced by the reaction exceeds the heat removed. The temperature rises, the reaction rate increases causing a further increase in the rate of the heat generation. The temperature rise can be very rapid leaving a limited time for correction.
Such reactions are normally controlled by cooling the reactor or by controlling the addition of the reactants. Loss of reactor cooling or agitation during the course of an exothermic reaction are two of the commonest causes of runaway reactions. A runaway reaction can cause the reactor contents to boil, generate vapor or explode, and over-pressurize the reactor, which can also be followed by release of toxic or flammable gases.
Effects of thermal runaway
A runaway exothermic reaction can have a range of results from the boiling over of the reaction mass, to large increases in temperature and pressure that lead to an explosion. Such violence can cause blast and missile damage. If flammable materials are released, fire or a secondary explosion may result. Hot liquors and toxic materials may contaminate the workplace or generate a toxic cloud that may spread off-site.
There can be serious risk of injuries, even death, to plant operators, and the general public and the local environment