Premcor Inc, Old Greenwich CT, has purchased a Williams Co refinery in Memphis TN with two truck-loading racks, three petroleum terminals, supporting pipeline infrastrucuture, and crude oil tankage. The refinery has 190,000-barrel-per-day production capability, and was purchased for $455 million. Williams, Tulsa OK, originally acquired the refinery as part of its purchase of MAPCO Inc in 1998.