Counter-Current Hydrocarbon Reactor for Olefin Yield
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Solution Overview
Problem
The petrochemical industry faces challenges in efficiently producing light olefins, such as ethylene, propylene, and butene, due to limitations in traditional methods like thermal cracking and fluid catalytic cracking, which often result in reduced yields and undesirable flow patterns.
Innovation Solution
A method involving a reactor with counter-current flow between catalyst and hydrocarbon feed, utilizing co-feeds like steam and oxygenates, and recycle streams to enhance cracking efficiency, with specific mass ratios and reactor configurations that promote dense bed fluidization and counter-current plug flow regimes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traditional thermal cracking or fluid catalytic cracking methods are used to produce light olefins, then the production process is simple, but the yield is reduced and undesirable flow patterns occur
Solution Approach 1:
The reactor is divided into multiple zones with different functions: an upper reaction zone for counter-current plug flow cracking and a lower reaction zone for dense bed fluidization. This segmentation allows each zone to operate under optimized conditions for maximizing light olefin yield while managing the overall system complexity through modular design
Solution Approach 2:
The system dynamically switches between different flow regimes in different zones - counter-current plug flow in the upper zone and dense bed fluidization in the lower zone. This dynamic operation allows the reactor to adapt to varying feed conditions and optimize productivity without requiring complete redesign of the entire reactor system
2Reliability
If counter-current flow is implemented between catalyst and hydrocarbon feed, then back-mixing and core-annular flow are prevented, but the device complexity increases
Solution Approach 1:
Instead of using complex active flow control mechanisms, the invention inverts the approach by allowing the catalyst to flow downward under gravity while the hydrocarbon feed flows upward, creating counter-current flow naturally. This inversion of the conventional co-current approach eliminates back-mixing and core-annular flow patterns without requiring complex flow control devices
Solution Approach 2:
The counter-current flow arrangement is self-sustaining, utilizing gravity to drive catalyst downward and pressure gradient to drive hydrocarbon feed upward. The system automatically maintains proper flow patterns without external control mechanisms, improving reliability while minimizing added complexity
3Productivity
If co-feeds of steam and oxygenates are used in specific mass ratios, then cracking efficiency is enhanced, but the process complexity increases
Solution Approach 1:
The invention optimizes cracking efficiency by changing the compositional parameters of the feed stream, specifically incorporating steam and oxygenates in controlled mass ratios (1:0.05:0.01 to 1:0.5:0.1 for hydrocarbon:steam:oxygenate). This parameter adjustment enhances cracking efficiency while the ratios are maintained within practical control ranges
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 increases the conversion of hydrocarbons to light olefins, improves yield, and prevents back-mixing and core-annular flow, leading to higher production of ethylene, propylene, and butene with reduced coke formation.
Implementation Method 1
Contacting the catalyst with the hydrocarbon feed stream may crack one or more components of the hydrocarbon feed stream and form a hydrocarbon product stream
Implementation Method 2
Light olefins may be produced by thermal cracking of petroleum fractions such as naphtha, kerosene, or gas oil
Implementation Method 3
specific mass ratios and reactor configurations that promote dense bed fluidization and counter-current plug flow regimes
Data Source
AI summary
Light olefins may be produced from hydrocarbons by a method including passing a hydrocarbon feed stream into one or more feed inlets of a reactor, with one or more co-feeds of steam, a recycle stream or oxygenates. The reactor may include an upper reactor portion defining an upper reaction zone and a lower reactor portion defining a lower reaction zone. The catalyst may move in a generally downward direction through the upper reactor portion and the lower reactor portion, and the hydrocarbon feed stream may move in a generally upward direction through the lower reactor portion and upper reactor portion such that the hydrocarbon feed stream and the catalyst move with a counter-current orientation. Contacting the catalyst with the hydrocarbon feed stream may crack one or more components of the hydrocarbon feed stream and form a hydrocarbon product stream.