Catalyst Cooler Regenerator Temperature Control
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Solution Overview
Problem
The regeneration of highly coked catalyst particles in oxygenates-to-olefins (OTO) systems poses challenges due to excessive heat liberation during the exothermic combustion process, leading to localized 'hot spots' and catalyst deactivation, while also requiring high catalyst circulation rates to maintain efficiency and reduce catalyst hold-up.
Innovation Solution
A method for controlling regenerator temperature by achieving high catalyst circulation rates between the regenerator and catalyst cooler, ensuring thorough mixing of cooled catalyst to minimize 'hot spots' and 'cold spots', and optimizing the catalyst circulation scheme to maintain uniform temperature and reduce catalyst hold-up.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If high levels of coke are maintained on molecular sieve catalyst compositions to maintain high prime olefin selectivity, then catalyst selectivity is improved, but excessive heat is liberated during regeneration causing localized hot spots and catalyst deactivation
Solution Approach 1:
The patent extracts the cooling function from the regenerator by introducing a separate catalyst cooler unit. Cooled inert material is withdrawn from the regenerator and used to cool incoming coked catalyst in an external cooler before regeneration, thereby removing excess heat from the system and preventing hot spots while maintaining high coke levels for selectivity
Solution Approach 2:
The patent introduces cooled inert material as an intermediary cooling medium. This inert material absorbs heat from the coked catalyst during cooling and then transfers this heat to the regenerator environment, acting as a thermal buffer that prevents direct overheating of the catalyst during regeneration while maintaining the necessary high coke levels for selectivity
2Temperature
If high catalyst circulation rates are used to control temperature and prevent hot spots, then temperature uniformity is improved, but catalyst hold-up in the system increases
Solution Approach 1:
The patent segments the catalyst circulation system into distinct functional zones: a regenerator zone for coke removal, a catalyst cooler zone for temperature control, and separate transfer lines. This segmentation allows independent optimization of each zone, enabling effective temperature control through targeted cooling without requiring excessive overall catalyst circulation, thereby reducing total catalyst hold-up
Solution Approach 2:
The patent applies preliminary cooling action by cooling the coked catalyst in the external catalyst cooler before it enters the regenerator. This pre-cooling reduces the thermal load on the regenerator, allowing for more uniform temperature distribution during regeneration without requiring excessively high circulation rates, thus minimizing catalyst hold-up while maintaining temperature uniformity
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 improves the efficiency of catalyst regeneration, reduces catalyst deactivation, and decreases the amount of catalyst required in the system, thereby extending its operational life and reducing exposure to deactivating conditions.
Implementation Method 1
a catalyst cooler means for cooling hot catalyst particles to a temperature below the ignition temperature of the coked catalyst composition
Implementation Method 2
the coke is at least partially removed from the catalyst by combustion with oxygen, which restores the catalytic activity of the catalyst and forms a regenerated catalyst. The combustion of the carbonaceous deposits from molecular sieve catalyst compositions during catalyst regeneration is an exothermic process.
Data Source
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AI summary
This invention relates to efficiently regenerating catalyst particles by minimizing the formation of localized "hot spots" and "cold spots" in a regeneration zone. Specifically this invention relates to a method for controlling regenerator temperature in an oxygenates-to- olefins system, comprising the steps of : contacting an oxygenate feed in a reactor with a catalytically effective amount of molecular sieve-containing catalyst under conditions effective for converting said oxygenate to a product containing light olefins and forming a coked catalyst; contacting a portion of the coked catalyst in a regenerator, having a catalyst bed height (Hc), an inlet height (Hi), and an outlet height (Ho), with an oxygen-containing regeneration medium under conditions effective to at least partially regenerate the coked catalyst; and conducting a portion of the catalyst from the regenerator to a catalyst cooler to form a cooled catalyst portion, wherein Ho is preferably greater than Hi.