Solid Carbon Injection for FCC Regenerator Heat Balance
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Catalytic cracking units face challenges in maintaining heat balance when processing weakly coking feedstocks with low Conradson carbon residue and high hydrogen content, leading to issues like afterburning and catalyst deactivation due to the need for continuous injection of liquid hydrocarbons or expensive preheat furnaces.
Innovation Solution
Injecting a solid carbon material with a high carbon content into the regenerator's dense fluidized bed of coked catalyst particles to increase the amount of coke burnt, ensuring homogeneous dispersion using structured packings to prevent hot spots and maintain heat balance without deactivating the catalyst.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If liquid hydrocarbons are continuously injected into the regenerator to maintain heat balance, then the heat balance is improved, but afterburning and catalyst deactivation occur
Solution Approach 1:
The invention changes the physical state parameter of the carbon material from liquid to solid form. By injecting solid carbon material instead of liquid hydrocarbons, the combustion occurs more uniformly and completely in the dense phase, preventing afterburning while maintaining heat balance. The solid carbon material burns more efficiently and does not cause the harmful effects associated with liquid hydrocarbon injection.
Solution Approach 2:
The invention uses solid carbon material (such as coal dust or petroleum coke) as a temporary, consumable substance to restore heat balance. This disposable carbon material is injected into the regenerator, burns quickly to provide the necessary heat, and is completely consumed in the process, avoiding the accumulation and harmful effects of liquid hydrocarbon injection.
2Loss of energy
If preheat furnaces are installed to maintain heat balance, then the heat balance is improved, but the operational cost increases
Solution Approach 1:
The invention extracts the heat balance function from the external preheat furnace system and relocates it to the regenerator by injecting solid carbon material. This eliminates the need for expensive external preheat furnaces and their associated operational costs, while maintaining the essential heat balance function within the existing regenerator infrastructure.
Solution Approach 2:
The regenerator becomes self-sufficient in maintaining heat balance by burning solid carbon material injected directly into it. The system uses its own internal combustion process to generate the necessary heat, eliminating the need for external preheat furnaces and reducing operational costs while maintaining thermal equilibrium.
3Temperature
If air throughput is increased to push combustion in the regenerator, then the temperature is improved, but the volume percentage of CO in flue gas increases
Solution Approach 1:
The invention changes the combustion parameters by using solid carbon material instead of liquid hydrocarbons. The solid carbon material combusts more completely at lower temperatures, achieving the necessary heat balance while producing less CO. This parameter change allows for reduced air throughput while maintaining temperature and improving combustion efficiency.
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 effectively increases the coke amount burnt in the regenerator, enhancing the heat balance and maintaining catalyst activity, thus ensuring efficient operation of the catalytic cracking unit while reducing the need for external preheating and minimizing catalyst make-up costs.
Implementation Method 1
Injecting a solid carbon material with a high carbon content into the regenerator's dense fluidized bed of coked catalyst particles to increase the amount of coke burnt
Implementation Method 2
Injecting a solid carbon material in the fluidized state, having a carbon content equal to or greater than 80% by weight, into a dense fluidized bed of coked catalyst particles
Data Source
AI summary
The present invention discloses a process for the catalytic cracking of a weakly coking feedstock having a Conradson carbon residue of 0.1% by weight and a hydrogen content of greater than 12.7% by weight, comprising at least a feedstock cracking zone, a zone for separating/stripping the effluents from the coked catalyst particles and a zone for regenerating said particles, characterized in that at least a solid carbon material in the fluidized state, having a carbon content equal to or greater than 80% by weight, is injected upstream of and/or during the catalyst regeneration step into a dense bed of coked catalyst.