Premcor Inc. agreed to spend $20 million to install new pollution control equipment that will cut emissions of sulfur dioxide and particulates, the US Justice Department said Thursday. St. Louis-based Premcor, an independent oil refiner, will also pay $2 million in civil penalties for violations of the Clean Air Act, the government said in a statement. The US government and the state of Illinois, where Premcor has an oil refinery, accused the company of making major modifications to the refinery without installing pollution control equipment mandated by the Clean Air Act's so-called new source review requirements.