HSFCC Reactor Feed Split for FCC Heat Balance
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Solution Overview
Problem
Existing fluid catalytic cracking (FCC) systems face challenges in heat balance, requiring supplemental fuels or catalyst coolers due to insufficient or excessive coke formation from hydrocarbon feeds, limiting the production of light olefins like ethylene and propylene.
Innovation Solution
A method for operating an FCC system with four reaction zones and a common regenerator, using heavy and light hydrocarbon feeds with different API gravities to balance heat load, eliminating the need for supplemental fuels or catalyst coolers by controlling the flow rate of regenerated catalyst.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If heavy hydrocarbon feed is used in FCC process, then coke formation increases providing sufficient heat for cracking reactions, but the system requires supplemental fuels or catalyst coolers to balance heat load
Solution Approach 1:
The FCC system is divided into multiple reaction zones (first, second, third, and fourth reaction zones) that process different hydrocarbon feeds separately. This segmentation allows each zone to be optimized for specific feed types, enabling heavy feed zones to produce excess coke heat while light feed zones require less heat, thereby achieving overall heat balance without supplemental fuels or catalyst coolers
Solution Approach 2:
Different reaction zones are assigned different feed types based on local heat requirements. The first and second reaction zones receive heavy hydrocarbon feed (lower API gravity) that produces more coke and heat, while the third and fourth reaction zones receive light hydrocarbon feed (higher API gravity) that produces less coke. This local differentiation of feed quality matches the heat generation needs of each zone
2Use of energy by moving object
If light hydrocarbon feed is used in FCC process, then supplemental fuels are required to provide sufficient heat for cracking reactions, but coke formation is insufficient
Solution Approach 1:
The system segments the FCC process into multiple reaction zones with different feed types. By separating heavy and light hydrocarbon feeds into different zones, the system can optimize each zone for its specific feed, allowing light feed zones to operate efficiently without requiring supplemental fuels while maintaining overall energy balance through the combined operation of all zones
Solution Approach 2:
The system changes the feedstock parameter (API gravity) across different reaction zones. Heavy feed (lower API gravity) is used in zones requiring high heat generation, while light feed (higher API gravity) is used in zones requiring lower heat generation. This parameter variation allows the system to achieve optimal energy balance and light olefin production without relying on supplemental fuels
3Ease of manufacture
If multiple reaction zones with different feeds are implemented, then heat balance is achieved without supplemental fuels or catalyst coolers, but device complexity increases
Solution Approach 1:
Multiple reaction zones are merged into a single integrated FCC system with a common regenerator. The spent catalyst from all zones is combined and regenerated together, and the regenerated catalyst is redistributed to the various reaction zones. This merging approach achieves heat balance across the system while avoiding the need for separate regeneration systems for each zone, thereby limiting the increase in overall system complexity
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
Achieves heat balance in the FCC system without supplemental fuels or catalyst coolers, enabling efficient production of light olefins using widely available hydrocarbon feeds with minimal processing.
Implementation Method 1
a feedstock is reacted in the presence of a catalyst, which forms coke on the surface of the catalyst
Implementation Method 2
The first portion and the second portion of the heavy hydrocarbon feed may be contacted with the cracking catalyst in the first FCC reactor and the second FCC reactor, respectively, at high severity conditions, where the contacting may cause at least a portion of the heavy hydrocarbon feed to undergo catalytic cracking
Implementation Method 3
The spent catalyst is passed to a regenerator where the coke is combusted to regenerate and heat the regenerated catalyst
Implementation Method 4
The hot, regenerated catalyst is then passed back to the FCC reactor where it provides heat for endothermic cracking reactions
Data Source
AI summary
A process for upgrading hydrocarbon feeds in an FCC system includes passing portions of a heavy hydrocarbon feed to a first reactor and a second reactor and passing portions of a light hydrocarbon feed to a third reactor and a fourth reactor. The heavy hydrocarbon feed has an API gravity of from 10° to 35° and the light hydrocarbon feed has an API gravity of from 38° to 100°. A cracking catalyst is passed to the reactors and contacted with the portions of the heavy and light hydrocarbon feeds. Reaction mixtures from the reactors are separated to produce an FCC effluent and spent cracking catalyst. The spent cracking catalyst is regenerated and passed back to the reactors. A flow rate of the cracking catalyst to the reactors is controlled based on determined heat balance requirements of each of the reactors.