Assessment of dust explosion with adipic acid and p-terephthalic acid in the powdered resin process

• Adipic acid (AA) and p-terephthalic acid (PTA) were the bulk raw materials used in the powdered resin manufacturing process.
• The Kst values of AA and PTA were 98 and 59 m bar/s; both can be classified to the St-1 explosion class.
• AA is the key material causing dust explosion in the powdered resin process.

In the powdered resin manufacturing process, methanol and acids are the main raw materials usually added through a hopper into a batch reactor. Under specific manufacturing process conditions, the pressure and temperature are high while the reactants undergo polymerization. Adipic acid (AA) and p-terephthalic acid (PTA) were the bulk raw materials used in this reaction to obtain various dust explosion characteristic parameters. Thermogravimetry results showed that AA and PTA experienced mass loss in temperature ranges of 200–220 and 300–330 °C, respectively. According to differential scanning calorimetry tests, the endothermic onset temperatures were 152.0 and 415.2 °C, the reaction heats were 183.4 and 204.3 J/g, and the endothermic peak temperatures were 153.1 and 424.7 °C, respectively. The maximum explosion pressure (Pmax) and the maximum rate of explosion pressure rise (dP/dt)max of AA and PTA were 6.9 bar and 361 bar/s and 6.4 bar and 218 bar/s, respectively. The Kst values of AA and PTA were 98 and 62 m bar/s; both can be assigned to the St-1 explosion class. The results showed that AA and PTA can induce a dust explosion. A proactive loss control strategy is mandatory in the powdered resin process for preventing dust explosion.