Moving Bed Reactor Flow Distribution for Olefin Oligomerization
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Solution Overview
Problem
Existing methods for transferring a co-current three-phase flow in moving bed reactors face challenges in achieving uniform flow distribution and controlling contact time between phases, leading to reduced activity, temperature spikes, and catalyst deactivation, particularly when converting oxygenates to distillate boiling range compounds.
Innovation Solution
A method involving a plurality of moving bed reactors with an olefin oligomerization catalyst, including a 1-D 10-member ring zeolite, where an olefin-containing feed and a recycle stream are exposed under adiabatic conditions to form distillate boiling range products, with separate phase introduction and recycling to manage temperature and catalyst activity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional methods are used to transfer three-phase flow in moving bed reactors, then the reactor operation is simplified, but uniform flow distribution cannot be achieved leading to reduced activity and temperature spikes
Solution Approach 1:
The reactor system is segmented into multiple moving bed reactors arranged in series, allowing each reactor to handle a portion of the three-phase flow independently. This segmentation enables better control over flow distribution in each reactor while maintaining overall system functionality.
Solution Approach 2:
A gas phase intermediary is introduced to facilitate the transfer of liquid feed and catalyst between reactors. The gas phase acts as a carrier that distributes the liquid and solid phases more uniformly throughout the reactor bed, preventing channeling and improving flow distribution.
2Ease of operation
If co-current flow is used in moving bed reactors, then catalyst regeneration is easier, but contact time control between phases becomes difficult leading to catalyst deactivation
Solution Approach 1:
The system dynamically adjusts the flow rates of gas, liquid, and solid phases independently to optimize contact time between reactants and catalyst. By making the flow rates adjustable and controllable, the system maintains optimal contact time while preserving the ease of catalyst regeneration inherent in moving bed reactors.
Solution Approach 2:
The system changes operational parameters such as gas velocity, liquid flow rate, and catalyst circulation rate to control the contact time between phases. By adjusting these parameters, the system prevents excessive contact time that would lead to catalyst deactivation while maintaining co-current flow benefits for regeneration.
3Reliability
If counter-current flow reactor is used to handle three-phase flow, then flow management is improved, but residence time is too high for reactions requiring short contact time
Solution Approach 1:
Instead of using counter-current flow where liquid and catalyst move in opposite directions, the system uses co-current flow where both move in the same direction. This inversion of the flow pattern reduces residence time and contact time between liquid and catalyst phases, preventing over-contact and catalyst deactivation while still maintaining reliable three-phase flow management through the moving bed configuration.
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 the cetane rating of diesel fuels, maintains catalyst activity, and achieves uniform mixing, overcoming issues of catalyst deactivation and temperature control in the production of distillate boiling range compounds.
Implementation Method 1
exposing an olefin-containing feed comprising C3-C8 olefins and a recycle stream comprising at least 20 wt % C5+ olefins to the catalyst flow in the plurality of moving bed reactors under olefin oligomerization conditions to form an oligomerized effluent
Implementation Method 2
the olefin oligomerization conditions can correspond to substantially adiabatic operation of the plurality of moving bed reactors
Data Source
AI summary
Systems and methods are provided for oligomerization of olefins to distillate boiling range products while also recycling naphtha boiling range olefins as part of the feed. By performing the olefin oligomerization while also recycling naphtha boiling range olefins, it has been discovered that the resulting distillate boiling range products can have an unexpected improvement in diesel combustion quality, such as an unexpected improvement in cetane rating. In order to manage coke formation and maintain consistent activity profile for the oligomerization catalyst, the reaction can be performed in a moving bed reactor. Additional temperature control can be maintained by the recycling of the naphtha boiling range portions of the oligomerization product back to the reactor.