Fluid Coking Nozzle Steam Ratio Optimization
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Solution Overview
Problem
In fluid coking processes, the formation of liquid-rich agglomerates of coke solids reduces liquid yields due to heat and mass transfer limitations, and increasing the gas-to-liquid ratio to improve dispersion increases steam usage, which is undesirable.
Innovation Solution
Modifying the operation of a fluid bed coking unit by reducing steam supply to upper feed nozzles and increasing the steam-to-oil ratio for lower nozzles, maintaining the overall steam-to-oil ratio, and optionally operating lowermost rings without oil feed, to enhance feed dispersion and liquid yield without increasing overall steam usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the gas-to-liquid ratio is increased to improve feed dispersion, then feed dispersion is improved, but steam usage increases
Solution Approach 1:
The patent applies different steam-to-oil ratios to different nozzle positions (upper vs lower rings) rather than using a uniform ratio throughout. This local differentiation allows optimization of feed dispersion in each zone while controlling overall steam consumption, resolving the contradiction between improved dispersion and reduced steam usage.
2Productivity
If liquid-rich agglomerates of coke solids are formed, then coke formation occurs, but liquid yields decrease due to heat and mass transfer limitations
Solution Approach 1:
By varying the steam-to-oil ratio according to nozzle position (upper vs lower rings), the patent creates locally optimized atomization conditions that prevent excessive liquid film formation and agglomerate creation, thereby improving heat and mass transfer efficiency while maintaining liquid yield.
Solution Approach 2:
The patent changes the steam-to-oil ratio parameter differently for upper and lower nozzle rings. This parameter modification optimizes the atomization quality and liquid film thickness on coke particles, preventing the formation of liquid-rich agglomerates that would limit heat and mass transfer.
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 feed dispersion and liquid yield by creating thinner oil films on particles, reducing heat and mass transfer limitations, and maintaining comparable steam consumption, thereby increasing overall liquid production.
Implementation Method 1
steam injected at the bottom of the vessel with the average direction of movement of the coke particles being downwards through the bed
Implementation Method 2
The heavy oil feed is heated to a pumpable temperature, mixed with atomizing steam, and fed through multiple feed nozzles
Implementation Method 3
Most of the entrained solids are separated from the gas phase by centrifugal force in one or more cyclone separators
Implementation Method 4
are returned to the dense fluidized bed by gravity through the cyclone diplegs
Implementation Method 5
converted to lighter, more useful liquid products by thermal decomposition (coking) at elevated reaction temperatures
Implementation Method 6
Steam is injected into a stripper section at the bottom of the reactor and passes upwards through the coke particles in the stripper as they descend from the main part of the reactor above and promotes fluidization of the particles in the bed
Data Source
Figure 1
AI summary
A fluid coking process is operated in a fluidized bed coking reactor in which a plurality of heavy oil inlet nozzles are arranged in a number of rings around the periphery of the dense bed reaction section at vertically spaced elevations, A heavy oil feed is injected with atomization steam through the nozzles into the fluidized bed, operating at a lower steam-to-oil ratio for the upper ring or rings of nozzles than for the lower ring or rings.