FCC Feed Injector Orifice Geometry for Atomization
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Solution Overview
Problem
Existing nozzle designs for atomizing petroleum feeds in fluid catalytic cracking (FCC) processes face challenges in achieving efficient dispersion of heavy, viscous fractions, leading to suboptimal product slate production due to thermal cracking and inefficient contact between feed and catalyst.
Innovation Solution
The development of a feed injector with an orifice having a general aspect ratio greater than 1.0 and a perimeter length-to-cross-sectional area ratio greater than 1.5, featuring an elliptical or rectangular shape with inward protrusions, which produces a substantially flat and fan-shaped spray pattern for improved atomization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional nozzles with circular orifices are used, then the device complexity is low, but the atomization quality is insufficient for heavy viscous petroleum fractions
Solution Approach 1:
The patent applies asymmetry by using non-circular orifice geometries (rectangular, elliptical, triangular, or polygonal shapes) instead of conventional circular orifices. These asymmetric shapes create uneven flow distribution and enhanced shear forces that improve atomization of heavy viscous feeds. The asymmetric geometry causes the liquid to break up more effectively into finer droplets, resolving the contradiction between maintaining simple device design and achieving high atomization quality.
Solution Approach 2:
The patent transitions from two-dimensional circular orifices to multi-dimensional complex geometries with varying cross-sectional areas along the flow path. The orifices incorporate features such as tapered sections, stepped configurations, and irregular boundaries that add dimensional complexity to the flow path. This dimensional enhancement creates more effective shear layers and turbulence, improving atomization quality without significantly increasing overall device complexity.
2Quantity of substance
If the degree of atomization is increased for heavy viscous feeds, then the droplet size decreases, but the energy requirement and process complexity increase
Solution Approach 1:
The patent changes geometric parameters of the orifice (shape, aspect ratio, cross-sectional area distribution) to optimize atomization efficiency. By carefully selecting orifice dimensions and shapes, the design achieves effective atomization of heavy feeds at lower pressure drops compared to conventional nozzles. The parameter optimization allows achieving fine droplet size distribution with reduced energy input, resolving the contradiction between droplet size reduction and energy consumption.
3Productivity
If non-dispersed liquid feed is used, then the device complexity is low, but thermal cracking occurs leading to light gases and coke formation
Solution Approach 1:
The patent implements preliminary atomization of the feed stream before it contacts the catalyst. The specially designed orifices create fine droplet dispersion in advance, ensuring that when the feed reaches the catalyst, it is already in an optimized state for catalytic cracking. This preliminary action prevents thermal cracking by avoiding large liquid pools that would otherwise undergo unwanted thermal decomposition, thus improving productivity while eliminating harmful thermal cracking products.
4Quantity of substance
If smaller orifice size is used, then droplet size decreases, but the risk of clogging and manufacturing precision requirements increase
Solution Approach 1:
The patent segments the orifice into multiple smaller openings or uses complex multi-dimensional geometries that distribute flow through several pathways. This segmentation prevents any single location from becoming a clog point while maintaining overall small effective orifice size for fine atomization. The segmented design allows feed to be distributed through multiple routes, reducing the risk of complete blockage and improving reliability without sacrificing droplet size control.
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 enhances the atomization process by producing smaller, more uniform droplets, thereby increasing the efficiency of the catalytic cracking process by reducing thermal cracking and improving contact between the feed and catalyst, leading to a more desirable product slate.
Implementation Method 1
The process of forcing a fluid under pressure through the orifice of a nozzle to form a fine dispersion of fluid droplets is known as atomization.
Implementation Method 2
The degree of atomization is a function of nozzle design, orifice size, fluid density, fluid viscosity, surface tension and pressure drop across the orifice.
Implementation Method 3
Other proposed designs include feeding hydrocarbon and feed concentrically through the nozzle, a hydrocarbon feed distributor feeding hydrocarbon through concentric nozzles located in the center of the FCC reactor
Data Source
AI summary
This invention relates to an apparatus and process for atomizing a petroleum feed. More particularly, a liquid petroleum feed is atomized with an atomization apparatus in which the apparatus has an orifice that produces a generally flat spray pattern of finely dispersed feed prior to contacting catalyst in a fluid catalytic cracking zone. The orifice has a general aspect ratio greater than 1.0 and a ratio of perimeter length-to-cross-sectional area greater than 1.5 relative to a perimeter-to-cross-sectional area ratio of a circular orifice of equivalent area. The apparatus can be used to atomize feed injected into the cracking zone of a fluid catalytic cracker.