Multi-Zone Fluidized Catalytic Conversion for Olefin Ratio Control
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Solution Overview
Problem
The existing methods for producing light olefins such as ethylene, propylene, and butylene face challenges in yield and selectivity, particularly due to the limitations of traditional steam cracking and MTO processes, which struggle with low ethylene/propylene ratios and catalyst deactivation, failing to meet the increasing demand for these chemicals.
Innovation Solution
A fluidized catalytic conversion method involving multiple reaction zones with specific temperature, pressure, and catalyst-to-feedstock ratios, including recycling of olefin-rich streams, hydrogenation of distillate oils, and introduction of oxygen-containing organic compounds, enhances the yield and selectivity of light olefins by optimizing the catalytic cracking process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traditional steam cracking is used to produce light olefins, then the production capacity increases, but the ethylene/propylene ratio is low and cannot meet market demand
Solution Approach 1:
The patent divides the catalytic cracking process into multiple reaction zones with different functions: a first reaction zone for initial cracking at higher temperature (600-800°C) to maximize ethylene production, and a second reaction zone for further conversion at lower temperature (400-650°C) to adjust the ethylene/propylene ratio. This segmentation allows independent optimization of each zone to achieve both high productivity and desired product distribution
Solution Approach 2:
The patent employs parameter changes by varying temperature, pressure, and catalyst-to-feedstock ratio across different reaction zones. The first reaction zone operates at 600-800°C with specific LHSV and catalyst-to-feedstock ratio to favor ethylene formation, while the second reaction zone uses 400-650°C with adjusted parameters to control propylene formation, thereby achieving the target ethylene/propylene ratio while maintaining high production capacity
2Adaptability or versatility
If MTO process is used to produce light olefins, then the production flexibility increases, but the catalyst deactivation occurs rapidly
Solution Approach 1:
The patent implements continuous catalyst circulation between the reaction zones and regenerator, maintaining continuous catalytic activity. The catalyst is continuously regenerated by burning off coke deposits in the regenerator and returned to the reaction zones, ensuring continuous useful action without significant deactivation. This continuous circulation system maintains high catalyst effectiveness throughout operation
Solution Approach 2:
The patent extracts the deactivation problem by separating the catalyst regeneration function from the reaction zones. The catalyst is withdrawn from the reaction zones to a dedicated regenerator where coke is removed, and the regenerated catalyst is returned to the reaction zones. This extraction of the deactivation issue allows the main reaction zones to focus on olefin production while the regenerator handles catalyst maintenance
3Quantity of substance
If heavy feedstocks are used as raw material, then the resource utilization improves, but the conversion difficulty increases
Solution Approach 1:
The patent segments the conversion of heavy feedstocks into two stages: first reaction zone for breaking down heavy molecules into smaller fragments, and second reaction zone for further cracking and aromatization. This segmentation makes the complex conversion of heavy feedstocks more manageable and efficient, improving resource utilization while controlling conversion difficulty
Solution Approach 2:
The patent uses composite catalyst systems with different functions in different zones. The first reaction zone employs catalysts optimized for cracking heavy molecules, while the second reaction zone uses catalysts optimized for aromatization and olefin formation. These composite catalytic systems work together to efficiently convert heavy feedstocks into valuable light olefins and aromatics
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
The method significantly improves the yield and selectivity of ethylene, propylene, and butylene, while also increasing the production of valuable by-products like benzene, toluene, and xylene, by integrating various catalytic conversion modes and utilizing heavy feedstocks effectively.
Implementation Method 1
contacting an olefin-rich feedstock with a catalytic conversion catalyst having a temperature of 650° C. or higher in a first reaction zone of a fluidized catalytic conversion reactor
Implementation Method 2
a fluidized catalytic conversion method for preparing light olefins from hydrocarbons
Implementation Method 3
separating the effluent of the fluidized catalytic conversion reactor to obtain reaction products and a spent catalyst
Implementation Method 4
hydrogenation of distillate oils
Data Source
AI summary
A fluidized catalytic conversion method for producing light olefins from hydrocarbons, includes the steps of conducting catalytic conversion of an olefin-rich feedstock in a first reaction zone of a fluidized catalytic conversion reactor, contacting a heavy feedstock with the reaction stream from the first reaction zone in a second reaction zone of the reactor for reaction, separating the effluent from the reactor, and recycling the resulting olefin-rich stream to the first reaction zone for further reaction. The method can improve the utilization rate of petrochemical resources and shows high yield and selectivity of ethylene, propylene and butylene.