Riser Feed Distributor Nozzle Design for FCC Catalyst Mixing
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Solution Overview
Problem
Current methods for distributing vapor streams in fluid catalytic cracking (FCC) processes are inefficient, requiring numerous distributors and often fail to achieve uniform mass distribution and mixing of catalyst streams, leading to undesirable hot spots and reduced product quality.
Innovation Solution
A distributor system that injects a vaporous hydrocarbon feed into a riser plenum, using a nozzle to direct the feed away from the radial center, and incorporates a dual-diameter nozzle to control jet outlet velocity and pressure drop, while also assisting in the mixing of catalyst streams at different temperatures through a mixed stream of catalysts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If conventional feed distributors are used to distribute vapor phase hydrocarbon feed, then the feed can be delivered to the reactor, but a significant number of distributors are required to achieve sufficient mass distribution
Solution Approach 1:
A vaporizing section is introduced as an intermediary component between the liquid feed source and the riser reactor. Liquid hydrocarbon feed is injected into this vaporizing section where it vaporizes and mixes with catalyst particles, creating a vapor-phase feed-catalyst mixture that is then introduced into the riser. This intermediary vaporizing section eliminates the need for multiple conventional distributors while achieving uniform mass distribution of the feed throughout the reactor.
2Device complexity
If open pipes or pipes with slots are used to distribute vapor stream, then the structure is simple, but the distribution of recycle stream in the riser is inefficient and uneven
Solution Approach 1:
The invention utilizes pneumatic principles by introducing a liquid feed stream into a vaporizing section where it vaporizes and is then carried by gas flow (steam or nitrogen) into the riser reactor. This pneumatic delivery mechanism ensures uniform distribution of the recycle stream throughout the riser, overcoming the limitations of simple open pipe structures that cannot achieve even distribution.
3Temperature
If carbonized and regenerated catalyst are mixed, then temperature uniformity is improved, but the distribution of hydrocarbon feed to the mixed catalyst stream becomes challenging
Solution Approach 1:
The hydrocarbon feed is vaporized in advance in a vaporizing section before being introduced into the riser reactor containing the mixed carbonized and regenerated catalyst. This preliminary vaporization action ensures that the feed is in the correct phase and uniformly distributed when it contacts the catalyst mixture, simplifying the overall distribution system while maintaining temperature uniformity benefits of mixed catalyst.
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
The system ensures even distribution of hydrocarbon feed and thorough mixing of catalyst streams, preventing hot spots and enhancing the production of light olefins by maintaining a more homogeneous temperature, thereby improving the quality and yield of FCC products.
Implementation Method 1
The hydrocarbon feed stream from the plenum is injected away from a radial center of the riser into the riser
Implementation Method 2
A dual-diameter nozzle may provide a means to independently set the jet outlet velocity and the distributor pressure drop
Implementation Method 3
A mixed catalyst with more uniform temperature avoids undesirable hot spots
Implementation Method 4
the regenerated and carbonized catalyst to reach a temperature equilibrium before contacting the hydrocarbon feed
Data Source
AI summary
A process and apparatus described is for distributing hydrocarbon feed to catalyst in a riser. Hydrocarbon feed is delivered to a plenum in the riser. Nozzles from the plenum inject feed into the riser to contact the catalyst. Streams of regenerated catalyst and carbonized catalyst may be passed to the riser and mixed around an insert in a lower section of a riser. The plenum may be located in the riser.