Catalytic cracking method suitable for processing feedstocks with low Conradson carbon residue, which comprises recycling a coking cut according to a novel technology

摘要

The process comprises introducing a coked catalyst in an outlet of a main reactor (1) into a stripper operating in fluidized bed and having a dense phase topped with a dilute phase (2), and recycling cuts of light cycle oil, heavy cycle oil and/or slurry using coking cut in a fluidized lateral capacity placed in derivation of stripper and along a transfer line. A catalytic cracking unit has Conradson carbon of less than 0.1 and hydrogen content of greater than 12.7 wt.%. An upper portion of the transfer line has its origin at an upper point that is greater than the dense phase of stripper. The process comprises introducing a coked catalyst in an outlet of a main reactor (1) into a stripper operating in fluidized bed and having a dense phase topped with a dilute phase (2), and recycling cuts of light cycle oil, heavy cycle oil and/or slurry using coking cut in a fluidized lateral capacity placed in derivation of stripper and along a transfer line. A catalytic cracking unit has Conradson carbon of less than 0.1 and hydrogen content of greater than 12.7 wt.%. An upper portion of the transfer line has its origin at an upper point that is greater than the dense phase of stripper. A lower portion of the transfer line has its return to the dense phase of the stripper at a point below the upper point. The lateral capacity is placed upstream of a control valve of the flow rate of catalyst, is placed on the lower portion of the transfer line, is provided with a vent line for the return of the gas products in the dilute phase of the stripper, and comprises a lower packing placed in its lower part and located below the point of introduction of the recycle stream, and a higher packing placed in its upper part and located above the point of introduction of the catalyst by the transfer line. The flow of extraction of the catalyst introduced into the lateral capacity is 50-100 kg/m 2/s. The residence time of the overall catalyst in the lateral capacity is 20-100 seconds. The catalyst taken from the dense phase of the stripper and brought into the lateral capacity is introduced into the dilute phase of the enclosure using a dispersion device. The coking cut is made within a tubular enclosure placed inside the stripper. An upper end of the enclosure opens into the dilute phase of the stripper, and the lower end of the enclosure opens into the dense phase of the stripper. The tubular enclosure is positioned so that the part immersed in the dense phase of the stripper is 30-100% of the total length of the tubular enclosure. A secondary reactor operates in parallel of the main reactor and works in operating conditions that is more stringent than the main reactor, and treats by mixing 4-5C olefinic cut and gasoline cut and/or recycled C5, C6, C7 or C8 oligomerat. An outlet temperature of the main reactor is 500-560[deg] C and C/O ratio is 5-10. An outlet temperature of the secondary reactor is 580-610[deg] C and the contact time is 50-200 ms. The recycled coking cut contains an external cut at the catalytic cracking unit type of wood or cellulose biomass, liquid hydrocarbon product from oil, pulverized coal, rich cut asphalt from a deasphalting unit, wax from a unit of indirect coal liquefaction, petroleum coke or a mixture of the fractions.