AM-00-61 THE DOMINO INTERACTION OF REFINERY PROCESSES FOR GASOLINE QUALITY ATTAINMENT

Description:

The composition of the North American gasoline pool is in a state of transition. The stringent sulfur specifications imposed by the Tier II regulations combined with environmental pressure on MTBE will dramatically impact the gasoline pool octane. Since the Complex Model controls the gasoline pool parameters, little flexibility is offered to the refiner to recover octane. These interacting parameters require different strategies depending on individual refinery configurations. MTBE removal from the pool will, in some cases, overload the existing alkylation plant. Dimerization of isobutylene will unload the alkylation unit but, compared to MTBE, will result in volume shrinkage and octane debit. Also, the reduction of sulfur from FCC gasoline will inevitably lead to a small but certain octane-barrel reduction in the FCC gasoline. These factors may heavily weigh in favor of higher severity and/or higher throughput operations of reformer units to produce more and/or higher octane reformate. Modifying the reformer operation will, in turn, bring back an old problem – benzene management. In many cases, the reformer feed fractionator has already been modified to change the cut-point of the feed to the reformer, thereby limiting benzene precursors. The interplay of these challenges will be discussed along with technological solutions to meet them.