Fluid Catalytic Cracking Olefin Separation for Ethylene Yield
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Solution Overview
Problem
Current Fluid Catalytic Cracking (FCC) processes face challenges in achieving high ethylene and propylene yields due to the lack of efficient separation of C4 and C5 paraffins from olefins, leading to increased material recycling and higher capital and utility costs.
Innovation Solution
A process configuration that includes a first catalytic reactor, a fractionation section, and a separation unit to selectively separate C4 and C5 olefins from paraffins, followed by a second catalytic reactor, allowing for improved ethylene and propylene production with reduced capital and utility costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If C4 and C5 olefins are recycled back to the FCC unit to increase ethylene and propylene yield, then the ethylene and propylene production is improved, but the amount of material that needs to be recycled increases rapidly due to inability to separate paraffins from olefins
Solution Approach 1:
The patent extracts C4 and C5 olefins from the mixed hydrocarbon stream using a separation unit positioned between the FCC reactor and the recycle stream. This extraction removes the valuable olefin components that need to be recycled while leaving paraffins and other components in the product stream, thereby reducing the quantity of material that must be recycled while maintaining high ethylene and propylene yields.
Solution Approach 2:
The patent segments the hydrocarbon stream into different components (olefins and paraffins) using a separation unit. By separating C4 and C5 olefins from the mixed stream, the process allows selective recycling of only the olefin portion, dividing the recycle stream into a smaller, more efficient quantity while improving ethylene and propylene production.
2Productivity
If a second reactor optimized to convert olefins to ethylene and propylene is added, then the ethylene and propylene yield is improved, but a separate recovery section is needed increasing device complexity
Solution Approach 1:
The patent merges the separation function with the existing FCC process configuration by positioning a separation unit in the product recovery section. Instead of adding a completely separate second reactor system with its own recovery section, the invention integrates olefin separation into the existing process flow, allowing the separated olefins to be recycled to the first FCC reactor, thereby reducing overall device complexity while maintaining improved ethylene and propylene yields.
3Device complexity
If C4 and C5 paraffins are not separated from olefins, then the process configuration remains simple, but the inert paraffin material must be recycled increasing loss of substance
Solution Approach 1:
The separation unit extracts C4 and C5 olefins from the mixed hydrocarbon stream, removing the valuable olefin components from the recycle stream. This extraction leaves paraffins and other inert components in the product stream rather than requiring their recycling, thereby reducing the loss of substance associated with recycling inert materials while maintaining relatively simple process configuration.
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 ethylene and propylene yields while simplifying the overall process recovery section, reducing dilution of the hydrocarbon feed to the second reactor, and lowering costs by effectively separating olefins from paraffins, resulting in yields greater than 20% (e.g., about 25%).
Implementation Method 1
An effluent stream of the first catalytic reactor is passed to a fractionation section to produce a first fractionation stream comprising C4 hydrocarbons
Implementation Method 2
The first fractionation stream is passed to a separation unit to produce a first separated stream having a greater concentration of C4 olefins than the first fractionation stream
Implementation Method 3
Fluid catalytic cracking (FCC) is a catalytic hydrocarbon conversion process accomplished by contacting heavier hydrocarbons in a fluidized reaction zone with a catalytic particulate material
Data Source
AI summary
The present invention discloses a process optimizing the yield of ethylene and propylene from a fluid catalytic cracking unit. The method combines a first catalytic reactor, a fractionation zone, a separation unit and a second catalytic reactor. The separation unit produces a first separate stream comprising C4 olefins and a second separate stream comprising C5 olefins. The separate streams may be combined and are passed to a second catalytic reactor for additional conversion to ethylene and propylene.