Thermal cracking of petroleum fractions in coke fluidised beds - to produce unsaturates, aromatics, coke and fuel fractions

摘要

Petroleum and petroleum products are thermally cracked to produce unsatd, and aromatic products or fuels by (a) fractionating the feedstock; (b) subjecting the fraction boiling above 350-500 degrees C to thermal cracking at 500-670 degrees C for a residence time of 10-15 sec in the presence of 25-100 wt. % steam in a pseudo-fluidised bed of coke; (c) subjecting the fraction boiling below 350-500 degrees C to cracking in cocurrent with the coke at 560-800 degrees C for a residence time of 0.3-3.0 secs; and (c) introducing the product from (c) into the fluidised bed. The process can be used to produce ethylene, aromatics and coke simultaneously from crudes, topped crudes, residual oils etc. The high-boiling fractions are subjected to less severe conditions than the thermally stable lighter fractions. The process is highly flexible in that the product ratios can be altered by varying the coke temp. and the proportion of the feedstock supplied to each reaction zone.