Role of steam cracking in the generation of benzene in crude oil tank fires extinguished with foam: A potentially unrecognized source of firefighter exposure

Benzene exposure and firefighting are both classified as Group 1-known human carcinogens. Industrial firefighters and HazMat workers respond to chemical emergencies involving hydrocarbon storage tank fires. The experimental phenomenon of benzene persistence in Chapter II heightened interest in further investigation of the role of steam-cracking and benzene in storage tank fires regarding a potential heightened exposure for hazardous material responders and firefighters. Chapter III findings exhibited a recreation of benzene persistence in a smaller scale tank at the OSU Fire Training Facility. Previous research involving crude oil storage tank fires have suggested benzene persistence in post-fire crude oil samples, thus, questioning a relationship to steam cracking from foam and water extinguishment techniques. Benzene concentration changes were noted using a novel method for steam injection into a hydrocarbon using a closed loop system. This system captured any liquid or vapor-phase changes in concentration for benzene, specifically, by comparing samples from pre- and post-steam injection treatment. This experiment challenged benzene precursors (naphtha, cyclohexane, and toluene) and the steam-cracking process by testing an element of low-temperature, low-pressure, low-quality, low-energy steam-injection (i.e., without fire) in a laboratory-controlled setting. A low-pressure apparatus carried steam from a pressurized steam-pot with controlled flow through a 20-micron sparger into the three separate “benzene precursor” products. The closed-loop system was sealed from the steam production, into the flask for steam application, and the collection of all vapor effluent displaced from the product headspace that was captured into tedlar bag samples. This novel method was developed for measurement of benzene concentrations (both air and liquid) through controlled analysis of steam cracking in attempt to recreate field-based experiences of benzene persistence in hydrocarbon storage tank fires. Air and liquid samples were analyzed using GC-FID and GCMS, the results suggested that low-quality, low-energy steam injection generated benzene in cyclohexane samples, both air and liquid and increased benzene concentrations in air samples for naphtha and toluene. These findings are important for hazard communication to firefighters and HazMat workers responding to hydrocarbon storage tank fires, as the exposure concerns to benzene may remain present post-fire.