A counter-current catalyst regenerator with at least two stages of counter-current contact along with a regenerator riser is proposed. Each stage may comprise a permeable barrier that allows upward passage of oxygen-containing gas and downward passage of coked catalyst into each stage, but inhibits upward movement of catalyst to mitigate back mixing and approximate true counter-current contact and efficient combustion of coke from catalyst. The regenerator riser may provide a passage to transport the catalyst and may serve as a secondary stage for coke combustion to provide the regenerated catalyst.

A counter-current catalyst regenerator with at least two stages of counter-current contact along with a regenerator riser is proposed. Each stage may comprise a permeable barrier that allows upward passage of oxygen-containing gas and downward passage of coked catalyst into each stage, but inhibits upward movement of catalyst to mitigate back mixing and approximate true counter-current contact and efficient combustion of coke from catalyst. The regenerator riser may provide a passage to transport the catalyst and may serve as a secondary stage for coke combustion to provide the regenerated catalyst.

A polyolefin production system is provided. The polyolefin production system includes a plurality of gas-phase polymerization tanks configured to polymerize an olefin gas to form a polyolefin, a compressor comprising an inlet and an outlet and being configured to compress a an olefin-containing gas, an individual gas feed line disposed at each of the gas-phase polymerization tanks and configured to guide the gas fed from the outlet of the compressor to each of the gas-phase polymerization tanks, an individual gas discharge line disposed at each of the gas-phase polymerization tanks and discharging the gas from each of the gas-phase polymerization tanks, and a first valve installed in each of the individual gas feed lines.

A polyolefin production system is provided. The polyolefin production system includes a plurality of gas-phase polymerization tanks configured to polymerize an olefin gas to form a polyolefin, a compressor comprising an inlet and an outlet and being configured to compress a an olefin-containing gas, an individual gas feed line disposed at each of the gas-phase polymerization tanks and configured to guide the gas fed from the outlet of the compressor to each of the gas-phase polymerization tanks, an individual gas discharge line disposed at each of the gas-phase polymerization tanks and discharging the gas from each of the gas-phase polymerization tanks, and a first valve installed in each of the individual gas feed lines.

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.

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.

A counter-current catalyst regenerator with at least two stages of counter-current contact is proposed. Each stage may comprise a permeable barrier that allows upward passage of oxygen-containing gas and downward passage of coked catalyst into each stage, but inhibits upward movement of catalyst to mitigate back mixing and approximate true counter-current contact and efficient combustion of coke from catalyst.

A counter-current catalyst regenerator with at least two stages of counter-current contact is proposed. Each stage may comprise a permeable barrier that allows upward passage of oxygen-containing gas and downward passage of coked catalyst into each stage, but inhibits upward movement of catalyst to mitigate back mixing and approximate true counter-current contact and efficient combustion of coke from catalyst.

A method is disclosed for fluidizing a spent catalyst in a regenerator during a combustion process. The combustor includes a vessel and an air distributor. The air distributor includes an air grid and a plurality of first nozzles extending from the air grid. Spent catalyst is introduced into the vessel. Air is provided to the vessel via the plurality of first nozzles at a base combustion air rate. Additional air is provided to the vessels via a plurality of second nozzles of a fluffing air distributor at a fluffing air rate that is between 0.5 wt % and 10 wt % of the base combustion air rate to fluidize the catalyst. The second nozzles have outlets that are disposed below the air grid and above a bottom head of the vessel.

A method is disclosed for fluidizing a spent catalyst in a regenerator during a combustion process. The combustor includes a vessel and an air distributor. The air distributor includes an air grid and a plurality of first nozzles extending from the air grid. Spent catalyst is introduced into the vessel. Air is provided to the vessel via the plurality of first nozzles at a base combustion air rate. Additional air is provided to the vessels via a plurality of second nozzles of a fluffing air distributor at a fluffing air rate that is between 0.5 wt % and 10 wt % of the base combustion air rate to fluidize the catalyst. The second nozzles have outlets that are disposed below the air grid and above a bottom head of the vessel.