FCC Riser Gas Distributor for Uniform Catalyst Mixing
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Solution Overview
Problem
Current methods for distributing fluidizing gas in fluid catalytic cracking (FCC) reactors are inefficient, particularly in evenly distributing gas to facilitate mixing of separate catalyst streams, leading to potential hot spots and nonselective cracking.
Innovation Solution
A distributor system that feeds a first stream of fluidizing gas into a chamber and a second stream outside the chamber within the riser, using a plenum with multiple nozzles to ensure even distribution and mixing of catalyst streams, enhancing the fluidization and mixing of catalysts and hydrocarbon feeds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a conventional steam ring distributor is used to distribute fluidizing gas, then the gas distribution structure is simple, but the equipment in the riser becomes cumbersome and gas distribution uniformity deteriorates
Solution Approach 1:
The distributor is segmented into multiple functional components: a plurality of gas inlet nozzles arranged circumferentially, a central catalyst inlet, and a distributed gas outlet structure. This segmentation allows each component to perform its specific function optimally while maintaining overall system simplicity
Solution Approach 2:
The distributor provides different gas flow characteristics at different locations: higher gas velocity at the periphery through the nozzles for effective fluidization, and controlled gas flow through the central region. This local differentiation ensures uniform gas distribution across the riser cross-section without requiring complex overall structure
2Device complexity
If open pipes or pipes with slots are used to distribute fluidizing gas, then the distributor structure is simple, but gas distribution efficiency and uniformity deteriorate
Solution Approach 1:
The distributor utilizes pneumatic principles by employing properly designed nozzle geometries and flow distribution channels that leverage gas pressure and velocity characteristics. The gas flow is optimized through the nozzle design to achieve efficient atomization and distribution without requiring complex mechanical components
Solution Approach 2:
The distributor transitions from simple one-dimensional pipe flow to two-dimensional radial distribution through circumferentially arranged nozzles. This dimensional change enables uniform gas distribution across the entire riser cross-section while maintaining relatively simple nozzle components
3Stability of the object's composition
If fluidizing gas is not evenly distributed, then the catalyst streams may not mix properly, but additional mixing equipment increases device complexity
Solution Approach 1:
The distributor performs preliminary mixing action by introducing fluidizing gas at multiple locations and angles before the catalyst streams fully converge. This preliminary gas injection creates turbulence and promotes catalyst stream mixing in advance, eliminating the need for additional complex mixing equipment downstream
Solution Approach 2:
The fluidizing gas acts as an intermediary medium that facilitates catalyst stream mixing. By distributing gas evenly across the riser, the gas creates fluidization currents that naturally mix the catalyst streams without requiring mechanical mixing devices
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 improves the uniformity of catalyst temperature and reduces the likelihood of hot spots, leading to more selective cracking and increased efficiency in hydrocarbon conversion processes.
Implementation Method 1
Inert fluidizing gas such as steam is distributed into the riser to fluidize the catalyst and to atomize the hydrocarbon feed. Fluidization of the catalyst pushes the catalyst up the riser so it can contact the hydrocarbon feed.
Implementation Method 2
A first stream of fluidizing gas is distributed from the plenum into a chamber in a riser and a second stream of fluidizing gas is distributed from the plenum into the riser outside of the chamber.
Data Source
AI summary
A process and apparatus described is for distributing fluidizing gas to a riser. Fluidizing gas is delivered to a plenum below the riser. A first stream of fluidizing gas is distributed from the plenum into a chamber in a riser and a second stream of fluidizing gas is distributed from the plenum into the riser outside of the chamber. First nozzles in the plenum have a first outlet in the chamber and second nozzles in the plenum have a second outlet outside of the chamber. Streams of regenerated catalyst and carbonized catalyst may be passed to the riser and mixed around the chamber in a lower section of a riser.