Catalyst Heating Riser for Light Olefin Yield Optimization
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Solution Overview
Problem
The demand for light olefins, particularly propylene, continues to grow, and existing methods for producing ethylene and propylene through hydrocarbon cracking processes face challenges in maximizing yields economically from both straight-run and processed hydrocarbon streams.
Innovation Solution
A process and apparatus that involves heating a cooled catalyst from a secondary reactor with a hot gas in a heating riser or heater, or using a riser to raise the catalyst temperature in an FCC regenerator for a primary FCC reactor, to increase the yields of light olefins produced from hydrocarbon feedstocks by optimizing reaction conditions in a secondary reactor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a secondary reactor is used to increase light olefin yields, then propylene and ethylene yields are improved (at least 26 wt% propylene and 10 wt% ethylene from VGO), but the device complexity increases due to additional heating equipment and riser systems
Solution Approach 1:
The heating chamber and riser are integrated into a unified system where the heating chamber directly feeds into the riser, which then connects to the secondary reactor. This merging of heating and reaction zones reduces the number of separate equipment pieces while achieving the dual function of catalyst heating and olefin production.
Solution Approach 2:
The riser serves multiple functions: it acts as a transport conduit for catalyst and hydrocarbon feed, provides a reaction zone for cracking, and facilitates heat transfer from the heated catalyst to the feedstock. This multi-functionality reduces the need for separate dedicated equipment for each function.
2Temperature
If catalyst is heated in a heating chamber with hot gas, then reaction temperature is improved for optimal cracking, but energy consumption increases due to additional heating requirements
Solution Approach 1:
The heating chamber is directly integrated with the riser system, allowing the hot gas and heated catalyst to flow directly into the reaction zone without intermediate cooling or transfer steps. This merging eliminates energy losses that would occur with separate heating and reaction vessels.
Solution Approach 2:
The system maintains continuous flow of hot catalyst and hydrocarbon feed through the riser, ensuring that the exothermic cracking reactions continuously generate heat that is immediately utilized by incoming feedstock. This continuous action minimizes energy losses and maintains optimal temperature without requiring additional external heating input.
3Volume of moving object
If a compact reactor design is used, then reactor size is reduced, but heat transfer efficiency may worsen due to limited space for heating equipment
Solution Approach 1:
The riser is positioned within or adjacent to the heating chamber, creating a nested configuration where the reaction zone is embedded within the heating zone. This allows maximum heat transfer surface area within minimal external volume, achieving compact design without sacrificing heat transfer efficiency.
Solution Approach 2:
The system utilizes vertical flow in the riser to create extended heat transfer path length without increasing horizontal footprint. By transitioning from a horizontal to vertical arrangement, the reactor achieves efficient heat transfer in a compact space by utilizing the vertical dimension.
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 enhances propylene and ethylene yields by optimizing the reaction conditions in a secondary reactor, allowing for higher propylene yields of at least 26 wt% and ethylene yields of at least 10 wt% from VGO feedstock, while maintaining a smaller reactor size and reducing coke generation, thus improving overall light olefin production efficiency.
Implementation Method 1
heating a cooled catalyst from a secondary reactor with a hot gas in a heating riser
Implementation Method 2
a riser to raise catalyst to be heated
Data Source
AI summary
A process and apparatus for heating catalyst is presented. Cooler catalyst is removed from a reactor and heated with a hot gas in a riser, heated in a heating tube or heated in a heating chamber. Heated catalyst is disengaged from the hot gas if necessary and returned to the reactor. The process and apparatus can be used for producing light olefins. The hot gas may be a flue gas from an FCC regenerator or a combustion gas from a heater.