FCC Unit Heat Balance via Aromatic Bottoms Coke Promotion

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Solution Overview

Problem

Fluidized catalytic cracking (FCC) units face heat deficiency when processing hydrogen-rich hydrocarbon feeds, as insufficient coke is produced to sustain the cracking reactions, and there is a need for beneficial uses of aromatic bottoms streams from naphtha reforming processes.

Innovation Solution

Passing an aromatic bottoms stream from the aromatics recovery complex to the FCC reactor to increase coke formation, thereby generating more heat during catalyst regeneration, and adjusting the flow rate based on operating parameters to ensure heat requirements are met.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If hydrogen-rich hydrocarbon feed is processed in the FCC unit, then the quality of feedstock is improved, but insufficient coke is produced to sustain the cracking reactions

Engineering Contradiction:

Improvecoke productionVSAvoidheat generation

Core Design Contradiction:

Quantity of substanceVSUse of energy by moving object

Solution Approach 1:

An aromatic bottoms stream is introduced as an intermediary substance to the FCC reactor. This stream serves as a mediator that promotes additional coke formation on the catalyst surface, thereby ensuring sufficient heat generation through subsequent combustion in the regenerator, while the main hydrogen-rich feedstock continues to be processed for high-quality products.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Temperature

If aromatic bottoms stream is passed to the FCC reactor, then heat requirements are satisfied through increased coke combustion, but the process complexity increases

Engineering Contradiction:

Improvecatalyst temperatureVSAvoidprocess complexity

Core Design Contradiction:

TemperatureVSDevice complexity

Solution Approach 1:

The aromatic bottoms stream, which would otherwise be a waste product requiring separate handling or disposal, is repurposed to serve a useful function in the FCC process. It acts as a coke promoter to ensure adequate heat generation, thereby giving waste material a second life and simplifying the overall process by eliminating the need for separate waste treatment systems.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Power

If coke production is increased to meet heat requirements, then the heat balance is improved, but catalytic activity is reduced due to coke deposits

Engineering Contradiction:

Improveheat balanceVSAvoidcatalytic activity

Core Design Contradiction:

PowerVSReliability

Solution Approach 1:

The aromatic bottoms stream is introduced at a controlled, partial rate that is sufficient to promote the necessary coke formation for heat balance but not excessive enough to completely deactivate the catalyst. This partial action ensures adequate heat generation while maintaining sufficient catalytic activity for continuous operation.

Inventive Principle:

Principle #16Partial or excessive action

Solution Approach 2:

The process utilizes feedback control where the amount of aromatic bottoms stream introduced is adjusted based on the heat balance requirements and catalyst performance. By monitoring process conditions and adapting the feed rate of the aromatic stream, the system maintains optimal coke levels that satisfy heat requirements while preserving catalytic activity.

Inventive Principle:

Principle #23Feedback

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This approach ensures the FCC unit maintains adequate heat for cracking reactions and provides a method to utilize previously waste aromatic compounds, enhancing operational efficiency and product yield.

Implementation Method 1

hydrocarbons are contacted with a solid catalyst in a fluidized state, which causes cracking of the hydrocarbons to produce one or more products or intermediate chemicals

Methodology Applied

Scientific EffectCatalytic cracking: Catalysis

Implementation Method 2

The cracking reactions in the FCC reactor are endothermic

Methodology Applied

Scientific EffectThermal cracking: Pyrolysis

Implementation Method 3

the coke deposits are removed from the FCC catalyst through combustion to at least partially or fully restore the catalytic activity of the FCC catalyst. Combustion of the coke deposits also produces heat

Methodology Applied

Scientific EffectCombustion: Combustion

Data Source

PatentUS11591526B1Methods of operating fluid catalytic cracking processes to increase coke production

Publication Date: 2023.02.28 SAUDI ARABIAN OIL CO

AI summary

A process for upgrading a hydrocarbon feed includes passing the hydrocarbon feed and an aromatic bottoms stream to an FCC unit including an FCC reactor and a catalyst regenerator. The hydrocarbon feed is hydrogen-rich having at least 12 wt. % hydrogen, and the aromatic bottoms stream is a bottoms stream produced from an aromatics recovery complex for processing reformate from naphtha reforming. The hydrocarbon feed and aromatic bottoms stream are cracked over the FCC catalysts to produce an effluent and spent FCC catalysts having coke deposits. The spent FCC catalyst is regenerated through combustion of the coke deposits. The hydrogen-rich hydrocarbon feed does not produce enough coke to satisfy the heat demand of the FCC reactor. Cracking the aromatic bottoms stream increases the amount of coke so that combustion of the additional coke during regeneration produces additional heat to satisfy the heat demand of the FCC reactor.