(Adds background, details on units involved and details fromregulatory filing.)
By Erwin Seba
HOUSTON, May 20 (Reuters) - Motiva Enterprises was restarting the 60,000-barrel- per-day (bpd) hydrocrackingunit at its 600,000-bpd refinery in Port Arthur, Texas, onTuesday, three days after it was shut by a malfunction, sourcesfamiliar with operations said.
All the refinery's sulfur recovery units (SRUs) had returnedto normal operation as of Monday night, the sources added. Theunits were shut by a malfunction on Monday morning.
A Motiva spokeswoman declined to discuss operations at therefinery on Tuesday.
This is the second time in two weeks Motiva has restartedthe hydrocracker at the Port Arthur refinery. The unit was shutfrom Wednesday to Friday last week due to a compressormalfunction.
The hydrocracker uses hydrogen under high pressure to makemotor fuels, producing greater amounts of diesel than does afluidic catalytic cracking unit, which makes more gasoline.
The three SRUs, which were added when the refinery doubledin size between 2007 and 2012, are part of the system thatremoves sulfur from motor fuels in compliance with U.S.environmental rules.
When the SRUs cannot operate, the fuels and other productsproduced by the newer units in the refinery may be forced tostop production, the sources said. One of the SRUs was restoredto operation shortly after the malfunction and the other twowere restarted late on Monday.
Workers on some units at the Port Arthur refinery wererequired to shelter inside their units when the SRUs went downbecause sulfur dioxide was released by the malfunction.
In a notice filed with the Texas Commission on EnvironmentalQuality, Motiva said sulfur dioxide and hydrogen sulfide werereleased. The company estimated four sources each released 101pounds (45.8 kilograms) of hydrogen sulfide and 501 pounds (227kg) of sulfur dioxide.
The estimated amount of hydrogen sulfide released from eachof the four sources exceeds the level permitted to the refineryby 1 pound, according to the notice filed with the TCEQ. Theestimated amount of sulfur dioxide released also exceeds thepermitted level by 1 pound.
A Motiva representative did not immediately reply to amessage asking how the estimates were arrived at and if theywould be revised in a later notice to the TCEQ.
Motiva is a 50-50 joint venture between Royal Dutch ShellPlc and Saudi Aramco. (Reporting by Erwin Seba; Editing by Terry Wade and Paul Simao)
