After two years of shopping, a partnership seeking to develop another ethane manufacturing plant has selected Belmont County, Ohio, as a final candidate for the facility. PTT Global Chemical, Thailand's largest chemical company, and Marubeni Corp., a Japanese trading and investment house, is considering building a world-scale petrochemical complex that would use natural gas liquids, particularly ethane, produced in the Marcellus and Utica shale plays, according to Ohio Gov. John Kasich's office.