Example of a Chemical Hazard Assessment

The process for the manufacture of a speciality chemical involved the reaction of paraformadehyde with a mixture of glycols using acid as a catalyst. The process was operated in a 16 m- reactor, with 3.5 bar steam heating, as a batch reaction — that is, all the reactants and catalyst were added to the reactor, which was then heated to 80°C and held at this temperature for 4 hours. 

The procedure used to evaluate the chemical reaction hazards was as 

Bretherick s Handbook of Reactive Chemical Hazards was used to check whether there were any literature references to hazards associated with the type of reaction, the starting materials and the products. No relevant information was found. 

The heat of the desired reaction between paraformaldehyde and glycols was estimated from the difference between the heats of formation of the reactants and products. As the heat of formation of paraformaldehyde is not available, the reaction between formaldehyde and propylene glycol was used — that is  

The estimated heat of reaction is therefore -111.1 J mol or -794 kJ kg reaction mixture. Assuming as a rough estimate that the specific heat of the reaction mixture is 2 kJ kg K , the adiabatic temperature rise can be estimated from  

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