Fluid Catalytic Cracking Patents (VI): Regenerator 2012-2013[1]

This is the sixth and final article in a review of patents in the area of Fluid Catalytic Cracking (FCC) for 2012-2013. The next article in this series will focus on FCC patents from 2014. The first five articles reviewed patents on catalyst additives, zeolites, cyclones, cracking catalysts and reactors. The current article will cover eight patents relating to FCC regenerators. Five of the eight patents relate to better mixing of the coked catalyst in the regenerator aimed at improving catalyst distribution, and permitting more even burning. These include systems to mix the coked catalyst with regenerated catalyst, systems to mix the coked catalyst with a carrier fluid, and systems to provide better mixing with combustion air. Of the three remaining patents, one relates to the use of a catalyst cooler, another relates to a fuel nozzle configuration for providing reactor heat demands for light feedstocks. The last relates to a two-step regenerator for operating at an increased level of coke on the catalyst. The accompanying reduced catalyst activity is useful for operating in a max-LCO mode.

Review of the patents indicates that substantial effort in regenerator design and implementation continues, particularly in the area of catalyst and combustion air mixing and/or distribution within the regenerator. The goal is to obtain as perfectly uniform distribution of the coked catalyst and combustion air within the regenerator as possible. A uniform distribution of coked catalyst and combustion air provides for efficient combustion of the coked catalyst. This results in more even or uniform burning, reduced after burn (lower temperatures where there is no catalyst to act as a heat-sink or absorber of the heat generated), improved environmental emissions (lower NOX), less destruction of the catalyst (improved activity retention) and less damage to the internal hardware/equipment.

The patents related to the regenerator are summarized below. Attached Table 1 lists relevant information on the patents. Table 2 contains a representative independent claim from each.

Regenerator

U.S. Patent No. 8,383,052 generally relates to a fuel nozzle configuration for providing heat demand while processing light feedstock. The claims are directed to a regenerator (106) having a heater (148), where the heater (148) is equipped with a fuel nozzle (204) for ejecting a mixture of fuel and oxygen-lean gas. The body (202) of the heater (148) has a number of windows (208) at one end of the body (202), where the vaporized mixture of fuel and oxygen-lean gas (210) exit the heater (148) into the dense phase catalyst bed (139).

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U.S. Patent No. 8,535,610 generally relates to a system for improved mixing of spent catalyst with regenerated catalyst. The regenerator design prevents after burn by providing a uniform mixture of spent and regenerated catalyst, with a more uniform temperature profile. The claims are directed to a first chamber (54) containing a gas distributer (80) and a cup (62), with a reactor catalyst conduit (48) extending to the cup (62). Recycled catalyst and spent catalyst are mixed in the cup (62) to raise the temperature of the spent catalyst before regeneration.

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U.S. Patent No. 8,563,455 generally relates to a system for the mixing of spent catalyst with regenerated catalyst. The design prevents after burn by providing a uniform mixture of spent and regenerated catalyst having a uniform temperature profile. The claims are directed to a process where coke-containing spent catalyst is delivered to the regenerator where it is contacted with oxygen. The coke is combusted to produce regenerated catalyst and flue gas. The regenerated catalyst is separated from the flue gas and recycled to a cup (62) in the regenerator (50) where it is mixed with spent catalyst. The mixture then exits downwardly.

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U.S. Patent No. 8,551,326 generally relates to a process for catalytically cracking a hydrocarbon feed using a regenerator having a first regeneration stage (2) that operates in partial combustion, and a second regeneration stage (8) operating in total combustion. Both stages contain fluidized beds. The catalyst residual coke rate from the first stage is between 0.3% and 0.7%, and less than 0.15% from the second stage (8). Catalyst flows from the first stage (2) to the second stage (8) via a transfer line (9) fed by a gas flow rate (10). The catalyst flow rate in the transfer line (9) is controlled by a plug valve (11) in the bottom of the transfer line (9). Operating at increased coke levels on the regenerated catalyst reduces the activity of the catalyst, which can be used for maximum-LCO operation.

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U.S. Patent No. 8,575,053 generally relates to a process for increasing mixing in a regenerator (50) using a dampening device. Such a device can be used to cause a mixing of streams of combustion air and streams of spent catalyst. Catalyst is introduced into the regenerator (50) through an inlet (54). Distribution gas is introduced below the inlet (54), and the catalyst and gas is lifted. Streamlines of gas in the dilute catalyst phase of the regenerator are dampened by redirecting the streamline, and catalyst is separated from the gas. The dampening device (94) can be a baffle (94D), a swirl arm (94A), a secondary T-disengager (94B) or an inverted can disengage (94C).Better mixing in the regenerator provides more uniform burning and reduced after burn.

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U.S. Patent No. 8,609,566 generally relates to a process for regenerating catalyst in a regenerator (30) having a catalyst cooler (100). Coke on a catalyst is combusted in a combustor chamber in the regenerator (30) and flue gas is separated from the catalyst in a disengaging vessel. Hot catalyst is transferred from the regenerator (30) to the catalyst cooler (100) through a hot catalyst inlet (106) where it is cooled. Catalyst in the cooler (100) is fluidized with air and withdrawn from the cooler (100). Air from the cooler (100) is vented to the combustor chamber.

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U.S. Patent No. 8,618,011 generally relates to the mixing of coked catalyst with a carrier fluid where the mixture is introduced to the upper surface (149) of the regenerator dense phase zone (145). The claims are directed to a process for regenerating catalyst where a hydrocarbon is cracked to produce a cracked hydrocarbon and coked catalyst particles. The coked catalyst particles are separated from the cracked hydrocarbons and then mixed with a carrier fluid and introduced to the dilute phase catalyst zone (155) through a distributor (150) onto the upper surface (149) of the regenerator dense phase (145). A gas is introduced into the lower zone of the dense phase (145), and the carbon is burned off the catalyst to provide a flue gas, heat and a regenerated catalyst.

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U.S. Patent No. 8,618,012 describes a process for regenerating a spent catalyst where the spent catalyst is mixed with a carrier fluid containing an oxygen-containing gas. The mixture is then introduced to or above the upper surface (149) the regenerator (140) dense phase catalyst zone (145). A gas is introduced into the lower zone of the dense phase (145), and the carbon is burned off the catalyst to provide a flue gas, heat and a regenerated catalyst.

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Table 1

FCC Patents — Regenerator

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Table 2

FCC Regenerator Claims

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My thanks to Mr. Ken Peccatiello of Peccatiello Engineering (www.PeccatielloEngineering.com) for reviewing the text.