(Adds quotes, details on project)
By Kristen Hays
HOUSTON, Sept 19 (Reuters) - Motiva Enterprises is planning to expand a hydrocracker and diesel hydrotreaterunit at its sprawling refinery in Port Arthur, Texas, accordingto a permit application seen Friday by Reuters, as global demandfor the fuel rises.
The application filed with Environmental Protection Agency'sRegion 6, which oversees Texas and surrounding states, said theproject at the largest U.S. refinery will increase diesel fueloutput and push the unit's design capacity to 105,000 barrelsper day from its current 82,000 bpd.
The company, a joint venture of Royal Dutch Shell and Saudi Aramco, wants to start construction in April 2015.
The hydrocracker was one of several new process units addedto the refinery as part of a $10 billion expansion that morethan doubled the plant's capacity, the permit application said.The expansion cost was not disclosed.
Other U.S. Gulf Coast refiners have also done or areplanning to undertake projects to ramp up diesel fuel output tocapitalize on growth in global diesel demand.
The boom in cheap U.S. and Canadian crude production hasprompted refiners in the region to maintain high refinery rates- 90 percent or more - as they increasingly export what is notneeded domestically.
Valero Energy Corp has added hydrocrackers to twoGulf Coast plants, and Marathon Petroleum Corp plans toexpand or revamp hydrocrackers at three refineries this year andin 2015.
Motiva's Port Arthur plant wants to do the same with itsproject.
"This is a very important project to the economic viabilityof our facility," the company said in the application.
The hydrocracker targeted for expansion is the only one atthe refinery that produces fuels. It converts gasoil into fuelgas, naphtha and diesel fuel. Its integrated dieselhydrotreating section processes diesel feedstocks.
Another hydrocracker at the plant processes lube oils and isnot part of the proposed project.
The expansion will involve changes to piping, pumps,exchangers, compressors and other emission sources.
"The overall operation of the unit will not be changed bythis project other than an increase to its capacity," theapplication said. (Additional reporting by Erwin Seba in Houston, editing by GCrosse)