Riser Plenum Distributor for FCC Feed Injection
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Solution Overview
Problem
Current methods for distributing vapor streams in fluid catalytic cracking (FCC) processes are inefficient, requiring multiple 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 nozzles to direct the feed away from the radial center, and incorporates a dual-diameter nozzle design to control jet outlet velocity and pressure drop, while also assisting in the mixing of catalyst streams at different temperatures through a structured insert within the riser.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If conventional feed distributors are used for vapor phase hydrocarbon feed, then the distribution system is simple, but sufficient mass distribution to the riser cannot be achieved
Solution Approach 1:
The feed distribution system is segmented into multiple nozzles arranged in a plenum, where each nozzle serves as an independent distribution element. This segmentation allows the vapor phase hydrocarbon feed to be distributed across multiple injection points simultaneously, achieving uniform mass distribution throughout the riser without requiring an excessive number of separate distributors.
Solution Approach 2:
The feed is injected away from the radial center of the riser into the riser volume, utilizing three-dimensional spatial distribution rather than relying solely on radial or axial positioning. This dimensional approach to injection creates more uniform mixing and distribution of the vapor phase feed throughout the catalyst bed.
2Quantity of substance
If open pipes or pipes with slots are used to distribute vapor stream, then the device complexity is reduced, but even distribution of the recycle stream in the riser is not achieved
Solution Approach 1:
A plenum is introduced as an intermediary component between the feed source and the riser. The plenum serves as a distribution chamber that receives the vapor phase hydrocarbon feed and directs it through multiple nozzles positioned away from the radial center, creating uniform stream distribution throughout the riser volume.
Solution Approach 2:
The system utilizes pneumatic principles to distribute the vapor phase feed through a plenum and nozzles. The vapor stream is injected into the riser through controlled nozzle outlets, leveraging gas flow dynamics and pressure differentials to achieve even distribution of the recycle stream throughout the catalyst bed.
3Manufacturing precision
If multiple streams of catalyst at different temperatures are mixed directly, then the mixing process is simple, but undesirable hot spots are generated reducing product quality
Solution Approach 1:
The mixing structure creates localized zones for catalyst streams to mix and equilibrate temperatures before contacting the hydrocarbon feed. By providing structured mixing regions with controlled flow paths, the system ensures uniform temperature distribution across the catalyst bed, preventing hot spots that would reduce product quality.
Solution Approach 2:
Multiple streams of catalyst at different temperatures are mixed and allowed to reach temperature equilibrium in a blending vessel before contacting the hydrocarbon feed. This preliminary mixing action ensures uniform temperature distribution, preventing hot spots during the actual cracking reaction and improving product quality.
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 solution ensures even distribution of the hydrocarbon feed and thorough mixing of catalyst streams, preventing hot spots and enhancing the homogeneity of temperature, thereby improving the quality and yield of products in the FCC process.
Implementation Method 1
a dual-diameter nozzle design to control jet outlet velocity and pressure drop
Implementation Method 2
assisting with mixing of separate streams of catalyst
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.