Policy Concentrates INDUSTRIAL SAFETY
Distillery mix-up releases chlorine Sulfuric acid erroneously added to sodium hypochlorite An accident at a distillery in Atchison, Kan., that released a cloud of chlorine gas was apparently caused by a chemical safety textbook example of what not to do: mixing sulfuric acid with sodium hypochlorite. The U.S. Chemical Safety & Hazard Investigation Board is probing the incident
A cloud of chlorine gas rolls through Atchison, Kan.
and is expected to make a final determination of the cause. The accident occurred on Oct. 21 at MGP, which describes itself as a leading supplier of premium distilled spirits and specialty wheat proteins and starches. It produces alcohol used for vodkas, gins, bourbons, and whiskeys. The company employs approximately 270 people. A supplier was delivering sulfuric acid to the facility, explains Trey Cocking, Atchison city manager, “and instead of putting the acid into the sulfuric acid tank, it went into the sodium hypochlorite tank. That led to a reaction.” When sodium hypochlorite is mixed with acid, chlorine gas is produced. Residents near the distillery began to smell a strong odor of chlorine and a thick fog emanated from the plant, sweeping
over the town of 11,000, according to news accounts. Those living north of the plant in the area of the plume were told to shelter in place. At one point, authorities considered evacuating the entire city. More than 135 people complained of burning lungs and difficulty in breathing and were treated at area hospitals, Cocking says. Only one person was admitted and has been released, he adds. Three company employees plus the truck driver delivering the acid required medical attention. In addition, 27 city employees have sought medical attention, including police, fire, and public works city staff. “We are a small community with only five firefighters, and maybe 15 emergency responders came in from nearby jurisdictions,” Cocking says. “We went through hazmat procedures and put water in the tank, and the reaction slowed and stopped.” The plant is now shut down. MPG would not comment on the incident.—JEFF
JOHNSON, special to C&EN
INDUSTRIAL SAFETY
Two workers died in 2013 Williams Olefins chemical plant explosion Errors in process management and equipment led to a 2013 fatal explosion at the Williams Olefins plant in Geismar, La., an investigation by the U.S. Chemical Safety &Hazards Investigation Board (CSB) recently concluded. Two workers died and 167 other workers reported injuries after hydrocarbons leaked from a plant operation, formed a vapor cloud, and ignited. The facility produces ethylene and propylene that are used by the petrochemical industry, said CSB Chair Vanessa Allen Sutherland, who unveiled the board’s conclusions earlier this month in Louisiana. A “reboiler”—a heat exchanger that supplies heat to a distillation column—catastrophically ruptured and caused the accident, CSB said in its report on the incident. The reboiler that failed was one of two in the system that provided heat to the pro-
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C&EN | CEN.ACS.ORG | OCTOBER 31, 2016
pylene fractionator—a distillation column that separates propylene and propane. The second reboiler was a backup and had been off-line for 16 months. Plant officials assumed the backup reboiler was clean and available for use. When the operating reboiler appeared to have fouled, plant operators began to shift operations to the idle reboiler. The plant operators did not know that the standby reboiler contained hydrocarbons and its pressure relief
Operators of the Williams Olefins plant wrongly assumed that backup equipment was clean and ready to use before the June 2013 accident, CSB says.
system was not in proper order, CSB found. As the reboiler’s heat increased, the confined liquid hydrocarbons expanded, resulting in a quick and dramatic pressure rise within the vessel. The shell ruptured, causing a release, an expanding vapor explosion, and a fire. A series of process safety management program deficiencies over the 12 years before the accident allowed the reboiler to be unprotected from overpressure problems, according to CSB. After the incident, Williams Olefins redesigned the reboilers, improved its management-of-change process to be more collaborative, and updated its process hazard analysis procedures, CSB said. Further improvements are needed, the agency added.—
JEFF JOHNSON, special to C&EN
CREDIT: HANDOUT/REUTERS/NEWSCOM (CLOUD); CSB (EXPLOSION)
U.S. Chemical Safety Board says multiple errors led to fatal accident
