Riser Insert for Catalyst Mixing
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Solution Overview
Problem
The existing processes for mixing carbonized and regenerated catalysts in fluid catalytic cracking (FCC) face challenges in achieving thorough mixing, leading to uneven catalyst temperatures and non-selective cracking, which affects the quality of product hydrocarbons.
Innovation Solution
The use of an insert in the reactor riser to obstruct direct passage between catalyst conduits, facilitating thorough mixing of regenerated and carbonized catalyst streams by passing them around the insert, which reduces catalyst volume and pressure drop, and enhances mixing efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a mixing chamber is used to mix carbonized and regenerated catalyst, then mixing is achieved, but the chamber becomes very large which increases capital cost and requires more catalyst inventory
Solution Approach 1:
The patent merges the mixing function with the existing riser structure by inserting mixing elements directly into the riser, eliminating the need for a separate large mixing chamber. The riser serves dual purposes: catalyst transport and catalyst mixing, thereby reducing overall system volume while maintaining mixing quality.
Solution Approach 2:
The mixing elements are nested within the existing riser structure, utilizing the available space inside the riser for mixing functionality. This nested arrangement allows the mixing chamber to be contained within the riser volume, effectively reducing the additional volume required for mixing without requiring a separate external mixing chamber.
2Manufacturing precision
If catalyst streams are mixed thoroughly to achieve uniform temperature, then non-selective cracking is reduced, but mixing time and equipment complexity increase
Solution Approach 1:
The mixing process is segmented into multiple zones within the riser, with different mixing elements positioned at different locations to address specific mixing requirements at different heights. This segmentation allows targeted mixing intervention points without requiring a completely complex mixing system throughout the entire riser.
Solution Approach 2:
Mixing elements such as baffles or inserts act as intermediary structures that facilitate catalyst stream interaction and mixing without requiring complex mechanical mixing equipment. These intermediary elements create turbulence and enhance contact between catalyst streams, achieving temperature uniformity through passive mixing mechanisms.
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 ensures more uniform catalyst temperatures, reducing non-selective cracking and improving the quality of product hydrocarbons by ensuring thorough mixing of catalyst streams before contacting the hydrocarbon feed.
Implementation Method 1
The first catalyst stream and the second catalyst stream are passed around the insert and up the riser. The insert creates flow disruption and turbulence that enhances mixing between the two catalyst streams.
Data Source
AI summary
A process and apparatus for mixing streams of regenerated and carbonized catalyst involves passing a catalyst stream around an insert in a lower section of a riser. The insert fosters mixing of the catalyst streams to reduce their temperature differential before contacting hydrocarbon feed.