Reappraisal of the role of turpentine vapor in noncondensible gas explosions

The extremely high burning velocity of turpentine (á-pinene) has been identified as the cause of numerous fires and explosions within the pulp and paper industry. Explosions in the noncondensible gas (NCG) collection systems caused by total reduced sulfur (TRS) compounds are usually minor and cause minimal damage, but explosions caused by turpentine can be catastrophic. When flammable conditions are created by insufficient dilution, air leakage into the system, or accumulation and breakthrough of TRS gases or turpentine vapor at a chip bin, it is conceivable that turpentine vapor creates near-optimum flammable mixtures more often than TRS gases do. In these cases, the burning velocity would be close to the maximum. On the other hand, when flammable conditions are created due to insufficient dilution of a stream of high velocity, low combustion gases (HVLC) or due to air leakage into a stream of low velocity, high combustion gases (LVHC), then the flammable mixture formed would be expected to have been off-stoichiometric: lean in the former case and rich in the latter case. In both cases, the burning velocity could have been much lower than in the near-stoichiometric mixture. The violence of explosions caused by turpentine is attributed to its capability to form near-stoichiometric mixtures more easily than the other components of NCGs.