Two-Stage Fluidized Bed Catalyst Regeneration Process
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Solution Overview
Problem
The existing catalyst regeneration processes for hydrocarbon oils suffer from low gas-solid contact efficiency, high catalyst inventory, and reduced regeneration speed, leading to decreased catalyst activity and selectivity due to coke and metal deposits, necessitating the development of a more efficient method to restore catalyst performance.
Innovation Solution
A two-stage fluidized bed regeneration process is employed, where spent catalyst is first treated in a fluidized bed with an oxygen-containing gas stream and optional steam at 550° C. to 750° C., followed by a second stage with a lower temperature and varying steam:oxygen ratios, enhancing catalyst residence time and gas velocity to achieve complete regeneration, and then the regenerated catalyst is reintroduced into the reactor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a low gas velocity fluidized bed single stage regeneration method is employed, then the operation is simple, but the gas-solid contact efficiency is low and regeneration speed is slow
Solution Approach 1:
The single stage regeneration process is divided into two distinct stages: a first fluidized bed regenerator for initial coke combustion at higher temperatures, and a second fluidized bed regenerator for final coke removal at lower temperatures. This segmentation allows each stage to be optimized independently, achieving both high regeneration speed and complete coke removal.
Solution Approach 2:
The process transitions from a single-stage to a two-stage regeneration system, adding a temporal and functional dimension to the regeneration process. The first stage operates at higher temperatures for rapid coke combustion, while the second stage operates at lower temperatures for complete coke removal, thereby increasing overall regeneration efficiency without compromising operational simplicity.
2Reliability
If high temperature oxidation is used to regenerate catalyst, then catalyst activity is restored, but catalyst selectivity decreases sharply due to metal passivation
Solution Approach 1:
The regeneration process dynamically adjusts temperature through two stages: the first stage uses high temperature (700-900°C) to restore catalyst activity by burning off coke, while the second stage uses lower temperature (500-700°C) to remove residual coke without excessive metal passivation. This dynamic temperature control balances activity restoration with selectivity preservation.
Solution Approach 2:
The process changes the temperature parameter between two stages: high temperature in the first stage for rapid coke combustion and activity restoration, followed by lower temperature in the second stage for complete coke removal with reduced metal passivation. This parameter change optimizes both catalyst activity and selectivity.
3Productivity
If catalyst inventory is reduced to improve regeneration efficiency, then regeneration speed increases, but catalyst makeup rate must increase to maintain equilibrium activity
Solution Approach 1:
The two-stage regeneration process ensures continuous and complete coke removal, preventing catalyst deactivation and extending catalyst life. By achieving more complete regeneration at each stage, the system reduces the frequency and amount of catalyst makeup needed, thereby reducing catalyst loss despite reduced inventory.
Solution Approach 2:
The process applies excessive action by using two sequential regeneration stages instead of one, ensuring complete coke removal and maximizing catalyst performance. This excessive regeneration action reduces the need for frequent catalyst replacement, offsetting the increased makeup rate associated with reduced catalyst inventory.
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 process results in more uniform catalyst activity, reduced dry gas and coke yields, and quicker approach to equilibrium catalyst activity, effectively improving product selectivity and extending catalyst life by burying and passivating heavy metals.
Implementation Method 1
contacted with an oxygen-containing gas stream to remove coke on the catalyst by a combustion reaction
Implementation Method 2
high temperature oxidation to burn off the coke on the catalyst
Implementation Method 3
contacted with steam and an optional oxygen-containing gas stream to carry out a further regeneration reaction
Implementation Method 4
first fluidized bed regenerator and contacted with an oxygen-containing gas stream
Implementation Method 5
contacted with an oxygen-containing gas stream and optional steam at 550°C to 750°C
Implementation Method 6
contacted with steam and an optional oxygen-containing gas stream to carry out a further regeneration reaction under the regeneration conditions including a temperature ranging from 550°C to 700°C
Implementation Method 7
effectively improving product selectivity and extending catalyst life by burying and passivating heavy metals
Data Source
AI summary
The object of the present invention is to provide a catalyst regeneration process which can improve catalyst selectivity. A first aspect of the invention is characterized in that a spent catalyst from a reactor is introduced into a first fluidized bed regenerator and contacted with an oxygen-containing gas stream and optional steam to carry out a coke combustion reaction, wherein the resultant mixture of the partially regenerated catalyst and flue gas is introduced into a second fluidized bed regenerator and contacted with steam and an optional oxygen-containing gas stream to carry out a further regeneration reaction, and then the regenerated catalyst is introduced into the reactor. A second aspect of the invention is characterized in that a spent catalyst from a reactor is introduced into a fluidized dense bed regenerator and contacted with an oxygen-containing gas stream and steam to carry out a coke combustion reaction, and then the regenerated catalyst is introduced into the reactor. The inventive processes result in a more uniform distribution of the regenerated catalyst activity; due to the exposure of the catalyst to a low temperature for a long time, a part of the heavy metals are buried by the matrix and the remaining are passivated. Thereby dry gas and coke yields decrease sharply when hydrocarbons are subjected to a catalytic cracking reaction on the regenerated catalyst.