UPDATE 1-Total says unit shut at Port Arthur refinery

(Recasts, adds details about regulators, background about refinery)

NEW YORK, June 17 (Reuters) - Total Petrochemicals USA said on Wednesday that it shut a unit at its 174,000-barrel-per-day refinery in Port Arthur, Texas, according to a filing with state pollution regulators.

The unit, which was only identified as "unit 836" was shut on Wednesday afternoon and is expected back on Thursday, the company said in a notice filed the Texas Commission on Environmental Quality.

Unit 836 has been identified in previous reports as a part of the refinery's system to remove sulfur from motor fuel.

On Friday, the refinery shut its gasoline-producing fluidic catatlytic cracking unit for unplanned work, according to notices filed with the Texas Commission.

Total Petrochemicals USA is the U.S. subsidiary of French energy giant Total SA (TOTF.PA).