Coked Catalyst Transport with Steam-Air Fluidizing Medium
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Solution Overview
Problem
In oxygenate to olefin (OTO) reaction systems, the high coke content in molecular sieve catalysts leads to excessive heat liberation during catalyst transportation, potentially damaging the catalyst and conduit materials, and existing transport methods do not adequately manage this heat to prevent material failure or optimal regeneration.
Innovation Solution
A process involving the transportation of coked catalyst through a conduit using a fluidizing medium comprising steam and air, with a controllable air-to-steam ratio, to maintain the temperature below a predetermined maximum and adjust based on detected temperature and pressure conditions, thereby controlling the regeneration process and preventing excessive heat buildup.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If coked catalyst is transported through a conduit with an oxygen-containing fluidizing medium (air) to achieve fluidized transport, then the catalyst can be effectively transported from reactor to regenerator, but excessive heat is liberated during transportation due to combustion of carbonaceous deposits, potentially damaging the catalyst and conduit materials
Solution Approach 1:
The patent introduces steam as an intermediary substance mixed with air in the fluidizing medium. The steam acts as a heat sink and diluent, absorbing excess heat from catalyst combustion and reducing the oxygen concentration available for combustion. This mediator approach allows the system to maintain fluidized transport while controlling the temperature rise in the conduit.
Solution Approach 2:
The patent changes the composition parameters of the fluidizing medium by incorporating steam alongside air. By adjusting the steam-to-air ratio in the fluidizing medium, the system controls the combustion rate of carbonaceous deposits on the catalyst, thereby managing the temperature profile during transport without compromising transport effectiveness.
2Productivity
If the amount of air in the fluidizing medium is increased to improve catalyst lifting capability, then transport efficiency increases, but excessive heat generation occurs during catalyst regeneration in the conduit
Solution Approach 1:
The patent converts the harmful effect of excessive heat generation into a beneficial control mechanism. By introducing steam, the system allows controlled combustion to occur but uses the steam's heat absorption capacity to manage the temperature. The heat that would otherwise be wasted or damaging is utilized to maintain catalyst temperature within optimal ranges while still achieving effective transport.
Solution Approach 2:
The patent modifies the fluidizing medium composition by adding steam, which changes the thermal and combustion characteristics of the system. This parameter change allows the system to maintain high transport efficiency while controlling the rate of coke combustion and the associated heat generation, preventing energy loss and material damage.
3Temperature
If steam is added to the fluidizing medium to reduce heat liberation, then temperature control improves, but the catalyst lifting capability may be reduced due to lower oxygen availability
Solution Approach 1:
The patent optimizes the steam-to-air ratio in the fluidizing medium to balance two competing requirements: temperature control and lifting capability. By carefully adjusting this composition parameter, the system achieves sufficient temperature moderation through steam while maintaining adequate oxygen concentration to provide the necessary lifting force for catalyst transport.
Solution Approach 2:
The patent employs dynamic control of the fluidizing medium composition, adjusting the steam and air ratios based on operating conditions such as catalyst coke content, transport rate, and conduit temperature. This dynamic adjustment allows the system to maintain optimal balance between temperature control and lifting capability across varying operational scenarios.
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 method effectively reduces the risk of conduit material damage and optimizes catalyst regeneration by managing the heat generated during transportation, ensuring the catalyst is transported safely and efficiently to the regenerator while maintaining desired conversion and selectivity characteristics.
Implementation Method 1
transporting the catalyst through a conduit in a fluidized manner with a fluidizing medium comprising steam and air
Implementation Method 2
the combustion of the carbonaceous deposits from molecular sieve catalyst compositions during catalyst regeneration is an exothermic process
Implementation Method 3
a significant amount of heat may be liberated within the conduit as the coked catalyst is transported through the conduit
Data Source
AI summary
This invention provides processes for transporting catalyst, preferably in an oxygenate to olefins reaction system. In one embodiment, an oxygenate contacts molecular sieve catalyst particles in a reactor under conditions effective to form an effluent stream comprising light olefins and forming coked catalyst particles. At least a portion of the coked catalyst particles are transported from the reactor or a device associated therewith to a catalyst regenerator through a conduit in a fluidized manner with a fluidizing medium comprising air and steam. At least a portion of the coked catalyst particles are regenerated in the catalyst regenerator to form regenerated catalyst particles, which are ultimately directed back to the reactor.