Adds comment from Mexican energy minister, context from regulatory filings.
A hydrogen sulfide (H2S) leak at Pemex's 312,500 b/d Deer Park, Texas, refinery on 10 October killed two workers and injured 35 more.
The leak occurred accidentally during maintenance, according to a regulatory filing submitted by Pemex this morning. Several units, including an amine unit, an alkylation unit, a hydrocracker and a sulphur recovery unit were promptly shut and flaring was initiated so the leak could secured.
Mexican energy minister Luz Elena Gonzalez said in a press conference in Mexico City Friday morning that the refinery was expected to restart operations later today. Deadly accidents at US refineries usually require extensive regulatory investigations by federal agencies, however, which require facilities or certain units at a plant to remain shut down.
H2S is an extremely hazardous gas commonly produced as a byproduct of refining, which can be processed into pure sulphur in a sulphur recovery unit (SRU) or removed by hydrotreating.
Shell's Deer Park petrochemical facility, located adjacent to Pemex's refinery, said it was doing a "controlled slowdown" of its operations as of 8:52pm yesterday in response to the accident as a precaution.
A flaring event was initially reported by a Deer Park Office of Emergency Management (OEM) social media account at 6:23pm ET on 10 October. A shelter in place advisory was issued for all Deer Park residents in a follow-up notice and Texas State Highway 225 running adjacent to the refinery was also closed to traffic. Areas of nearby Pasadena were also placed under a shelter in place advisory. The Deer Park shelter in place was lifted at 10pm ET.
The Pemex refinery had previously reported an aromatic concentration unit (ACU) leak on 6 October.
Amine units strip H2S from methane gas generated by hydrotreaters. Alkylation units produce high-octane blendstocks used in gasoline. Hydrocrackers use hydrogen, pressure, and catalyst to produce distillates and gasoline low in contaminants like sulphur. SRUs help to remove sulphur and other impurities from refinery products and gas streams.
