HOUSTON, May 13 (Reuters) - A coking unit malfunctioned on Saturday at Exxon Mobil Corp's 344,500 barrel per day (bpd) Beaumont, Texas, refinery, according to a notice the refinery filed with the U.S. National Response Center.
A wet gas compressor tripped out of operation on the coker, according to the unit.
A hydrocracking unit was temporarily shut last week at the refinery.
A coker increases the amount of refinable material produced from a barrel of crude oil and makes petroleum coke, a coal substitute from residual oil. A hydrocracker uses hydrogen to increase motor fuel production from a barrel of oil.