Stronger refining margins and higher throughput volumes helped U.S. refining giant Valero Energy Corporation (NYSE: VLO) beat analyst estimates of fourth-quarter earnings. Valero on Thursday kicked off the earnings season for the U.S. refiners by reporting an adjusted net income attributable to Valero stockholders of $1.2 billion, or $3.82 per share, for the fourth quarter. This easily beat the analyst consensus estimate of $3.27 earnings per share in The Wall Street Journal. Strong refining margins boosted the net income, as the refining margin…