Segmented Feed Distributors for FCC Riser Conversion
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Solution Overview
Problem
The fluid catalytic cracking (FCC) process faces challenges in distributing and mixing multiple feedstocks effectively within the riser, particularly with heavy residues, due to high viscosity and boiling points, which requires high temperatures, pressures, and additional feedstocks, leading to reduced conversion efficiency and increased costs.
Innovation Solution
The implementation of a segmented distribution system within the FCC riser using multiple sets of feed distributors positioned at different radii and elevations to create distinct zones of varying catalyst density, allowing for tailored feedstock injection based on crackability, thereby improving mixing and conversion without the need for physical barriers or additional feedstocks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If high feed temperature is used to improve resid feed distribution, then distribution is enhanced, but catalyst-to-oil ratio is reduced
Solution Approach 1:
The feed injection system is segmented into multiple distributors positioned at different radial distances from the riser center. This allows different feedstocks to be injected at different locations, creating distinct flow regimes and catalyst-to-oil ratios in different zones of the riser, thereby maintaining effective distribution without requiring excessively high temperatures
Solution Approach 2:
Different regions of the riser are created with different catalyst densities and flow characteristics by positioning feed distributors at varying radial distances. The inner region and outer region have different catalyst-to-oil ratios, allowing each feedstock to contact catalyst under optimized local conditions without compromising overall distribution effectiveness
2Ease of operation
If high pressure drop is used to improve resid feed distribution, then distribution is enhanced, but utility costs increase
Solution Approach 1:
Multiple feed distributors are arranged at different radial positions, creating segmented flow paths that reduce the pressure drop required for feed distribution. The geometric arrangement of distributors allows feed to be introduced at optimal locations without requiring excessive pressure differential, thereby reducing utility costs while maintaining distribution effectiveness
3Ease of operation
If high atomizing steam is used to improve resid feed distribution, then distribution is enhanced, but riser space is occupied
Solution Approach 1:
The feed distribution system uses multiple distributors positioned at different radial distances, which segments the feed injection process and eliminates the need for high volumes of atomizing steam. The distributors create effective feed distribution through their geometric arrangement and flow dynamics, occupying minimal riser space while maintaining distribution effectiveness
4Loss of energy
If blending with gasoline boiling range feed is used to decrease viscosity, then viscosity is reduced, but overall conversion is suppressed
Solution Approach 1:
Different feedstocks are injected at different radial positions in the riser, creating distinct flow zones. This segmentation allows heavy resid feed to be distributed effectively without requiring blending with lighter gasoline boiling range feeds, thereby maintaining high overall conversion while reducing viscosity through controlled feed placement rather than blending
Solution Approach 2:
The system creates different local conditions in the riser by positioning feed distributors at varying radial distances. The inner and outer regions have different catalyst densities and flow characteristics, allowing each feedstock to be processed under optimized local conditions without suppressing overall conversion through blending
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 enhances the distribution and mixing of feedstocks with the FCC catalyst, achieving superior catalyst-to-feed contacting and improved conversion efficiency while reducing the penalties associated with high temperatures, steam rates, and utility costs compared to current practices.
Implementation Method 1
Fluid catalytic cracking (FCC) is a catalytic conversion process for cracking heavy hydrocarbons into lighter hydrocarbons by bringing the heavy hydrocarbons into contact with a catalyst composed of finely divided particulate material in a fluidized reaction zone
Implementation Method 2
High temperature regeneration burns the coke from the spent catalyst
Implementation Method 3
An inert lift gas such as steam may be used to accelerate catalyst in a lower section of the riser below or during introduction of the feed
Implementation Method 4
Catalyst and hydrocarbon feed are transported upwardly in the riser by the expansion of the gases that result from the vaporization of the hydrocarbons and other lift and dispersion media as well as molar expansion of cracked products upon contact with the hot catalyst
Data Source
AI summary
A fluid catalytic cracking (FCC) process for cracking multiple feedstocks in a FCC apparatus comprising a first set of feed distributors having first distributor tips and a second set of feed distributors having second distributor tips is provided. A first feed is injected into the riser from first distributor tips. A second feed is injected into the riser from second distributor tips. The first distributor tips and the second distributor tips are positioned at different radii in the riser. The first feed and the second feed are cracked in the riser in the presence of an FCC catalyst to provide a cracked effluent stream. The first distributor tips and the second distributor tips are located into a region of lower catalyst density and a region of higher catalyst density respectively in the riser.