Asymmetric Two-Section Cracking Reactor for Light Olefins
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Solution Overview
Problem
There is a continued industry demand for efficient processes and apparatuses to produce light olefins, such as ethylene, propylene, and butene, which are typically produced through different reaction processes based on chemical feed streams from crude oil refining operations, but existing technologies lack flexibility and efficient heat management in cracking reactions.
Innovation Solution
The described reactor system consists of an upstream and downstream reactor section, with the upstream section having at least 150% of the cross-sectional area of the downstream section, operating in fast fluidized, turbulent, or bubbling bed modes, and utilizing a supplemental fuel to heat the catalyst, allowing for flexible reaction types like cracking, dehydrogenation, and methanol-to-olefin reactions, and enabling the use of various feedstocks based on price and availability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a conventional single-section reactor is used for cracking, then the reactor structure is simple, but the processing flexibility and heat management efficiency are insufficient
Solution Approach 1:
The reactor is divided into two distinct sections: a lower section with a larger cross-sectional area for feeding and initial reaction, and an upper section with a smaller cross-sectional area for product withdrawal. This segmentation allows each section to be optimized for its specific function, thereby improving processing flexibility without requiring complete redesign of the entire reactor system.
Solution Approach 2:
Different sections of the reactor are designed with different cross-sectional areas to create locally optimized conditions. The lower section's larger area facilitates better heat distribution and feed introduction, while the upper section's smaller area enhances product withdrawal efficiency. This local differentiation improves overall processing flexibility while maintaining structural feasibility.
2Use of energy by moving object
If coke is burned to heat the catalyst in cracking reactions, then no supplemental fuel is needed, but insufficient coke is formed to generate adequate heat
Solution Approach 1:
A supplemental fuel is introduced as an intermediary energy source to heat the catalyst. This supplemental fuel compensates for the insufficient heat generated by coke combustion, ensuring adequate temperature for cracking reactions without requiring excessive coke formation, which would be harmful to the catalyst.
3Productivity
If different reaction processes are used for different feed streams, then each feed stream can be optimally processed, but the number of separate processes and catalysts required increases
Solution Approach 1:
The reactor system is designed with universal applicability to handle multiple feed streams (naphtha, butane, ethane, propane) and perform various reaction types (cracking, dehydrogenation, dehydration, methanol-to-olefin). By optimizing the two-section structure and catalyst circulation system, a single reactor can replace multiple specialized reactors, thereby maintaining high productivity while reducing process complexity.
4Temperature
If the upstream reactor section has a larger cross-sectional area, then heat management and feed distribution are improved, but the overall reactor volume increases
Solution Approach 1:
The reactor employs an asymmetric design where the lower section has a larger cross-sectional area than the upper section. This asymmetric configuration optimizes heat management and feed distribution in the lower section while keeping the upper section compact for efficient product withdrawal. The asymmetric design achieves better thermal performance without proportionally increasing the total reactor volume.
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 configuration enhances processing flexibility, reduces production costs by allowing the selection of feedstocks based on availability, and ensures consistent light olefin production with high yields, as demonstrated by product streams containing at least 50% light olefins, while avoiding coke formation issues by using supplemental fuels for heating.
Implementation Method 1
burning a supplemental fuel source in the combustor to heat the catalyst
Implementation Method 2
reacting the feed stream with a cracking catalyst in the reactor to form a product stream
Data Source
AI summary
According to one or more embodiments presently disclosed, light olefins may be formed by a method that may comprise introducing a feed stream into a reactor, reacting the feed stream with a cracking catalyst in the reactor to form a product stream, and processing the cracking catalyst. The reactor may comprise an upstream reactor section and a downstream reactor section. The upstream reactor section may be positioned below the downstream reactor section. The upstream reactor section may have an average cross-sectional area that is at least 150% of the average cross-sectional area of the downstream reactor section.