A method for producing a polyolefin is provided. The method includes steps of polymerizing an olefin in a first gas-phase polymerization tank to obtain polyolefin-containing particles, transferring the polyolefin-containing particles to a second gas-phase polymerization tank through a transfer pipe, and polymerizing an olefin in the presence of the transferred polyolefin-containing particles in the second gas-phase polymerization tank. A connection place between the first gas-phase polymerization tank and the transfer pipe is higher than a connection place between the second gas-phase polymerization tank and the transfer pipe. 130 kPaP.sub.1P.sub.20 is satisfied, where P.sub.1 represents the pressure in the first gas-phase polymerization tank and P.sub.2 represents the pressure in the second gas-phase polymerization tank.

A catalytic cracking process includes the following steps: i) subjecting a heavy feedstock oil to flail catalytic cracking; ii) separating the catalytic cracking reaction product obtained from step i) to obtain a catalytic cracking gasoline and a catalytic cracking light cycle oil; iii) splitting the catalytic cracking gasoline to obtain a light gasoline fraction, a medium gasoline fraction and a heavy gasoline fraction; iv) subjecting the catalytic cracking light cycle oil to hydrogenation to obtain a hydrogenated light cycle oil); v) mixing a portion of the light gasoline fraction with at least a portion of the hydrogenated light cycle oil to obtain a mixed fraction; vi) subjecting the mixed fraction to catalytic cracking; and vii) subjecting a portion of the medium gasoline fraction to flail catalytic cracking. The process is capable of producing more catalytic cracking gasoline, reducing the olefin content of the catalytic cracking gasoline, and increasing its octane number.

A catalytic cracking process includes the following steps: i) subjecting a heavy feedstock oil to flail catalytic cracking; ii) separating the catalytic cracking reaction product obtained from step i) to obtain a catalytic cracking gasoline and a catalytic cracking light cycle oil; iii) splitting the catalytic cracking gasoline to obtain a light gasoline fraction, a medium gasoline fraction and a heavy gasoline fraction; iv) subjecting the catalytic cracking light cycle oil to hydrogenation to obtain a hydrogenated light cycle oil); v) mixing a portion of the light gasoline fraction with at least a portion of the hydrogenated light cycle oil to obtain a mixed fraction; vi) subjecting the mixed fraction to catalytic cracking; and vii) subjecting a portion of the medium gasoline fraction to flail catalytic cracking. The process is capable of producing more catalytic cracking gasoline, reducing the olefin content of the catalytic cracking gasoline, and increasing its octane number.

This invention describes a novel and efficient processing scheme that can be used to transform a vacuum residue feedstock into 0.5 wt % sulfur bunker fuel that fulfills the specifications required by the International Maritime Organization (IMO).

This invention describes a novel and efficient processing scheme that can be used to transform a vacuum residue feedstock into 0.5 wt % sulfur bunker fuel that fulfills the specifications required by the International Maritime Organization (IMO).

The presently disclosed subject matter provides methods for producing olefins and/or aromatics from coker naphtha. In a non-limiting embodiment, a method for producing aromatics includes hydrogenating the coker naphtha stream in the presence of a first catalyst to remove diolefins and sulfur, if any, to obtain a hydrogenated stream and subjecting the hydrogenated stream to aromatization in the presence of a second catalyst to produce an aromatic-rich stream that includes benzene, toluene and xylene. In certain embodiments, a method for producing olefins includes hydrogenating the coker naphtha stream in the presence of a first catalyst to remove diolefins and sulfur, if any, to obtain a hydrogenated stream and subjecting the hydrogenated stream to catalytic cracking in the presence of a second catalyst to produce an olefin-rich stream that includes ethylene, propylene and aromatics.

The presently disclosed subject matter provides methods for producing olefins and/or aromatics from coker naphtha. In a non-limiting embodiment, a method for producing aromatics includes hydrogenating the coker naphtha stream in the presence of a first catalyst to remove diolefins and sulfur, if any, to obtain a hydrogenated stream and subjecting the hydrogenated stream to aromatization in the presence of a second catalyst to produce an aromatic-rich stream that includes benzene, toluene and xylene. In certain embodiments, a method for producing olefins includes hydrogenating the coker naphtha stream in the presence of a first catalyst to remove diolefins and sulfur, if any, to obtain a hydrogenated stream and subjecting the hydrogenated stream to catalytic cracking in the presence of a second catalyst to produce an olefin-rich stream that includes ethylene, propylene and aromatics.

This invention describes a novel and efficient processing scheme that can be used to transform a vacuum residue feedstock into 0.5 wt % sulfur bunker fuel that fulfills the specifications required by the International Maritime Organization (IMO).

This invention describes a novel and efficient processing scheme that can be used to transform a vacuum residue feedstock into 0.5 wt % sulfur bunker fuel that fulfills the specifications required by the International Maritime Organization (IMO).

A fluid catalytic cracking unit (FCCU) for production of petrochemical feedstock fractions comprises a first reactor to receive a stream of desalinated crude oil and produce a first cracked product stream; a second reactor to receive a stream of light cracked naphtha (LCN) and produce a second cracked product stream; a third reactor to receive a bottom stream and produce a third cracked product stream; and a fractionating column and gas concentration section to separate components of the first cracked product stream, the second cracked product stream, and the third cracked product stream to produce, upon further fractionation, Ethylene, Propylene, Butylene, Benzene, Toluene and Xylene as the petrochemical feedstock fractions.