Annular Downer Reactor Radial Catalyst Distributor
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Solution Overview
Problem
Existing catalytic cracking processes, particularly downflow reactors, face challenges in efficient catalyst distribution and contact with hydrocarbon feeds, leading to suboptimal product selectivity and increased coke formation due to radial distribution issues and space requirements.
Innovation Solution
An annular downer reactor with a novel radial catalyst distributor is employed, featuring stationary and movable parts to ensure uniform radial distribution and control of catalyst flow, combined with an upflow riser regenerator for efficient contact and compact design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If a downflow reactor is used to improve product selectivity and reduce coke formation, then product selectivity improves and coke formation decreases, but catalyst distribution becomes difficult to control and radial distribution deteriorates with increased diameter
Solution Approach 1:
The catalyst distributor is divided into multiple segments including a central distributor and multiple radial distributors positioned at different radii. Each distributor has multiple outlets that collectively cover the entire cross-section of the downflow reactor, ensuring uniform catalyst distribution across the reactor diameter while maintaining controllability.
Solution Approach 2:
Different regions of the reactor cross-section are served by different distributors with tailored outlet configurations. The central distributor addresses the core region while radial distributors handle peripheral regions, allowing each zone to receive optimized catalyst flow according to its specific requirements for uniform distribution.
2Productivity
If the reactor diameter is increased to handle larger feed rates, then productivity increases, but radial distribution of catalyst deteriorates
Solution Approach 1:
The catalyst distribution system transitions from a single-point or single-plane distribution approach to a multi-dimensional distribution network. Radial distributors are positioned at different radii and angles, creating a three-dimensional distribution pattern that maintains uniformity across larger reactor diameters by addressing radial distribution challenges in multiple spatial dimensions.
Solution Approach 2:
The reactor cross-section is divided into multiple zones, each served by dedicated distributor outlets. This segmentation allows the system to scale to larger diameters while maintaining distribution uniformity by locally optimizing catalyst flow to each zone rather than relying on a single distribution point.
3Area of stationary object
If a compact reactor design is implemented to minimize space requirements, then space efficiency improves, but catalyst-feed contact efficiency may be compromised
Solution Approach 1:
The annular downflow reactor is nested within the upflow riser structure, with the downflow reactor positioned concentrically inside. This nested configuration allows both reactors to share the same vertical space, achieving compact footprint while maintaining sufficient catalyst-feed contact efficiency through the annular geometry that provides adequate reaction zone volume.
Solution Approach 2:
The reactor design utilizes vertical space more effectively by implementing concentric annular geometry. The annular downflow reactor creates an additional reaction zone within the existing riser footprint, transitioning from horizontal space utilization to vertical and radial space optimization, thereby maintaining contact efficiency while reducing footprint.
4Adaptability or versatility
If separate reactors are used for different catalytic processes, then process flexibility is maintained, but equipment space and complexity increase
Solution Approach 1:
The upflow riser regenerator and annular downflow reactor are merged into a single integrated hardware system. The riser serves as both a feed injection zone and a regenerator, while the annular space provides the downflow reaction zone. This merging maintains process flexibility by preserving distinct functional zones while eliminating the need for separate external reactors, thereby reducing overall equipment space and interconnections.
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 configuration achieves maximum contact efficiency between catalyst and hydrocarbon feed, enhancing product selectivity and reducing coke formation while minimizing space and hardware requirements.
Implementation Method 1
radial distributor for catalyst and an annular downer reactor... The radial distributor has equal numbers of stationary and movable parts placed one after another to cover the entire opening at the inlet of annular downer reactor
Implementation Method 2
In down flow reactor, the catalyst along with the hydrocarbon vapors flow downwards and the slip velocity between the catalyst flow and the hydrocarbon flow is lower than that of the riser reactor resulting in reduced coke formation and higher distillate yield
Implementation Method 3
an upflow riser regenerator for burning off the coke deposited on the catalyst
Implementation Method 4
U.S. Pat. No. 5,296,131 discloses a concept of falling curtain of catalyst which is claimed to provide maximum exposure of catalyst to oil... The apparatus in the current invention mainly comprises of radial distributor for catalyst and an annular downer reactor
Data Source
AI summary
An apparatus which is an integral hardware consisting of an annular downer reactor and a concentric upflow riser regenerator for catalytic cracking of hydrocarbon feed to is disclosed. The annular downer reactor terminates in annular stripper which is also concentric with the regenerator. The regenerator, reactor and stripper are in fluid connection with each other. The apparatus is highly compact and provides efficient contact between circulating catalyst and hydrocarbon feed. The proposed hardware includes a novel radial distributor for providing improved control and radial distribution of catalyst inside the downflow reactor. The radial distributor has equal numbers of stationary and movable parts placed one after another to cover the entire annular opening at the bottom of the regenerated catalyst vessel. The radial distributor is concentric with regenerator and located between the catalyst holding vessel and the reactor. A process for catalytic cracking using the invented apparatus is also disclosed.