Fluid Catalytic Cracking Regenerator Heat Integration
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Solution Overview
Problem
Fluid catalytic cracking units operating with clean feeds face challenges such as low regenerator temperatures, catalyst regeneration difficulties, and increased carbon dioxide emissions due to low coke yield, which can lead to catalyst attrition and equipment damage when methane is burned to provide heat.
Innovation Solution
Introducing an uncombusted stream of oxygen and hydrocarbons, such as C1-C5 hydrocarbons or hydrogen, into the regenerator to provide heat without igniting the mixture before it enters the combustor, thereby avoiding excessive gas velocities and thermal damage to the catalyst.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If methane is burned in the heater to provide heat duty, then regenerator temperature is improved, but catalyst attrition and thermal damage occur
Solution Approach 1:
The patent changes the operational parameters of the heater by controlling the fuel gas flow rate and air flow rate to maintain outlet temperature below the catalyst damage threshold (790°C) while providing sufficient heat duty. The heater operates in a controlled combustion mode that prevents excessive temperatures from reaching the catalyst.
Solution Approach 2:
The patent introduces an intermediary cooling mechanism where a portion of the combustion products or process gases are used to cool the heater outlet region, acting as a thermal buffer between the combustion zone and the catalyst stream, thereby protecting the catalyst from thermal damage.
2Reliability
If the air grid limits outlet temperature to prevent metallurgical failures, then equipment safety is improved, but regenerator temperature remains insufficient for effective regeneration
Solution Approach 1:
The patent segments the heating and regeneration functions into distinct zones within the regenerator system. The heater provides controlled heating in one zone, while the combustion of coke on catalyst particles occurs in another zone, allowing temperature management that protects equipment while achieving effective regeneration.
Solution Approach 2:
The patent applies preliminary heating to the catalyst or process gases before they enter the main regeneration zone, using the heater to raise temperatures to a level that facilitates subsequent coke combustion without requiring excessive temperatures that would damage equipment.
3Manufacturing precision
If clean feeds with low sulfur and shorter carbon chains are processed, then product quality is improved, but regenerator temperature decreases due to low coke yield
Solution Approach 1:
The patent employs a self-heating mechanism where the regenerator system recovers heat from the combustion of coke on spent catalyst particles and uses this heat to preheat incoming catalyst or process gases, creating a self-sustaining thermal cycle that maintains regenerator temperature without external fuel addition.
Solution Approach 2:
The patent makes the regenerator system multi-functional by combining the coke combustion function with a heat recovery function. The same equipment that regenerates catalyst also serves as a heat source for preheating processes, thereby maintaining temperature efficiency when processing clean feeds with low coke yield.
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 allows for effective catalyst regeneration while reducing carbon dioxide emissions and preventing catalyst attrition, maintaining product quality and extending equipment lifespan without significant capital or operating cost increases.
Implementation Method 1
Introducing an uncombusted stream of oxygen and hydrocarbons, such as C1-C5 hydrocarbons or hydrogen, into the regenerator to provide heat without igniting the mixture before it enters the combustor
Data Source
AI summary
One exemplary embodiment can be a process for regenerating catalyst in a fluid catalytic cracking unit. Generally, the process includes providing a feed to a riser of a reaction vessel, and providing a stream to a distributor positioned within a void proximate to an inlet receiving unregenerated catalyst in a regenerator. The feed can include at least one of a gas oil, a vacuum gas oil, an atmospheric gas oil, a coker gas oil, a hydrotreated gas oil, a hydrocracker unconverted oil, and an atmospheric residue.