FCC Feed Injector Atomization via Contraction and Expansion
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Solution Overview
Problem
Existing apparatuses for mixing and atomizing hydrocarbon streams using a diluent/dispersion stream face challenges in achieving a desired distribution of droplet size, particularly for heavy hydrocarbon feeds, and require simpler and more reliable designs.
Innovation Solution
The apparatus comprises concentric inner and outer conduits with a diluent/dispersion stream distributor, contraction, and expansion members in tapered sections, strategically placed to break down hydrocarbon streams into smaller droplets without additional diluent injection, ensuring efficient mixing and atomization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If multiple mixing chambers and contraction/expansion members are added to improve atomization, then droplet size distribution improves, but device complexity increases
Solution Approach 1:
The mixing process is divided into three distinct chambers (primary, secondary, tertiary) with specific functions: the primary chamber mixes hydrocarbon feed with diluent, the secondary chamber introduces first portion of dispersion stream, and the tertiary chamber introduces second portion of dispersion stream. This segmentation allows progressive atomization while maintaining manageable complexity in each individual chamber.
Solution Approach 2:
The contraction member dynamically increases kinetic energy of the mixture entering the tertiary chamber, while the expansion member subsequently allows pressure recovery. This dynamic variation in flow conditions enhances atomization efficiency without requiring permanently complex structural arrangements.
2Device complexity
If feed is injected without proper atomization, then device complexity is reduced, but heat transfer and vaporization efficiency deteriorate
Solution Approach 1:
The apparatus performs preliminary atomization of the hydrocarbon feed into fine droplets before the feed enters the reactor. The three-chamber mixing system pre-breaks down the feed into droplets with sizes matching catalyst particle sizes, ensuring that when the feed contacts the hot catalyst, immediate and efficient heat transfer and vaporization occur without requiring complex in-reactor atomization systems.
3Device complexity
If droplet size is not matched to catalyst particle size, then atomization complexity is reduced, but contact efficiency and product selectivity deteriorate
Solution Approach 1:
The invention creates different local mixing conditions in different chambers: the primary chamber creates initial mixing with diluent, the secondary chamber adds dispersion stream with specific flow characteristics, and the tertiary chamber completes the atomization process. Each chamber is optimized for its specific function, creating locally appropriate droplet sizes that match catalyst particle sizes for optimal contact efficiency.
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 design achieves a uniform distribution of droplet sizes, enhancing contact with catalysts for faster vaporization and product selectivity, while maintaining a simple and reliable construction.
Implementation Method 1
The contraction member in said apparatus is used to increase the kinetic energy of the secondary mixture entering into the tertiary chamber
Implementation Method 2
a spray hole at the end socket of said inner sleeve... said spray hole being adapted to atomize a tertiary mixture comprising said hydrocarbon and said diluent/dispersion stream
Implementation Method 3
the contact of the feed droplets and catalyst particles will be poor and the heat transfer from the hot catalyst particle to feed will be less, resulting in low vaporisation of feed
Data Source
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AI summary
The present invention discloses a method and an apparatus for mixing and atomizing a hydrocarbon stream using a diluent/dispersion stream. In one embodiment, the apparatus comprises: an inner conduit and an outer conduit concentric to each other to define an annular space, said outer conduit having an inlet for receiving the hydrocarbon stream and an outlet for dispensing a mixture comprising the hydrocarbon and the dispersion/diluent streams; a diluent/dispersion steam distributor being in connection with the inner conduit and defining a central orifice and a first set of orifices, said first set of orifices adapted to direct a first portion of the dispersion/diluent stream into the annular space and said central orifice adapted to direct a second portion of the diluent/dispersion stream into the inner conduit; atleast one contraction member and expansion member, said contraction member located downstream of the first set of orifices and said expansion member located downstream said expansion member; the inner conduit located downstream of said expansion member comprises a second set of orifices, said second set of orifices disposed on a periphery of the inner conduit and adapted to dispense a second portion of the dispersion/diluent stream into the annular space.