The potential FCCU product yield changes result from new catalyst formulations, higher reactor temperatures, higher catalyst-to-oil ratios and improved reactor system designs. Higher olefins production comes at the expense of FCCU gasoline yield. Increased olefins production and the resultant gasoline overcracking will lower reactor effluent molecular weight. Many refiners have targeted reactor yield shifts that decrease reactor effluent molecular weight by 5-10 numbers. Some West Coast refiners are targeting reactor effluent molecular weights as low as 75. These yield shifts associated with higher C3/C4/C5 olefins production will improve oxygenates and alkylate production, but the impact on major equipment and the FCCU utilities system will be significant. Yield changes will increase the main fractionator, wet gas compressor and gas concentration unit major process equipment loadings. This article will evaluate the effect such changes will have on the major equipment (excluding reactor/regenerator) of a 50,000-bpd unit.
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