Pyrolysis Furnace Coil Segmentation for Olefin Yield
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Solution Overview
Problem
Current pyrolysis processes for producing lower olefins from wide boiling range hydrocarbon feedstocks are limited by the need for separate furnaces or severe cracking conditions, which are costly and inefficient, as they do not allow for optimal cracking of different fractions within a single furnace.
Innovation Solution
A process utilizing a pyrolysis furnace with a convection section and at least two sets of independently controlled radiant section pyrolysis coils to separate and crack different fractions of a wide boiling range hydrocarbon feedstock, allowing for specific cracking severities for each fraction to enhance C2 and C3 mono-olefin production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single pyrolysis furnace is used to process wide boiling range hydrocarbon feedstock, then equipment cost is reduced, but cracking precision for different fractions deteriorates
Solution Approach 1:
The radiant section is divided into multiple independently controlled coil sets (first set and second set), each capable of receiving different feed fractions and operating at different cracking severities. This segmentation allows precise control of cracking conditions for different hydrocarbon fractions within a single furnace.
Solution Approach 2:
Each coil set is equipped with independent temperature control and feedstock injection capabilities, allowing different local cracking conditions to be optimized for different fractions. The first coil set operates at conditions optimal for lighter fractions while the second coil set operates at conditions optimal for heavier fractions.
2Manufacturing precision
If separate furnaces are used for different fractions, then cracking precision is improved, but device complexity and cost increase
Solution Approach 1:
Multiple coil sets that would traditionally require separate furnaces are merged into a single pyrolysis furnace with a common convection section and radiant section. Each coil set maintains independent control capabilities, achieving the precision of separate furnaces while reducing overall equipment complexity and cost.
Solution Approach 2:
The single pyrolysis furnace is designed to perform multiple functions by accommodating different coil sets that can process different hydrocarbon fractions simultaneously. The furnace structure and control system are configured to handle diverse feedstocks and cracking conditions within one unit.
3Productivity
If severe cracking conditions are applied to all fractions, then olefin yield is improved, but coke formation increases
Solution Approach 1:
Different coil sets operate at different cracking severities matched to their specific feed fractions. Lighter fractions receive more severe cracking to maximize olefin yield, while heavier fractions receive milder cracking to minimize coke formation. This localized optimization prevents excessive coke while maintaining high olefin production.
Solution Approach 2:
Cracking severity parameters (temperature, residence time) are independently adjusted for each coil set based on the specific properties of the feed fraction being processed. This allows optimization of olefin yield for each fraction without uniformly applying severe conditions that would cause excessive coke formation.
4Reliability
If milder cracking conditions are applied to prevent coke formation, then olefin yield deteriorates, but processing reliability is improved
Solution Approach 1:
The coil system is segmented into multiple independently controlled sets, allowing different cracking severities to be applied to different fractions. This enables lighter fractions to receive severe cracking for high olefin yield while heavier fractions receive milder cracking for coke control, optimizing both productivity and reliability simultaneously.
Solution Approach 2:
Cracking parameters are dynamically adjusted for each coil set based on feed composition and desired product distribution. This allows the system to achieve high olefin yields from lighter fractions without sacrificing reliability, as each fraction is processed at its optimal cracking severity.
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 yield of lower olefins by allowing separate cracking of fractions at optimal conditions within a single furnace, improving profitability and reducing costs associated with multiple furnaces or severe cracking limitations.
Implementation Method 1
heating and partially vaporizing the feedstock, and feeding the partially vaporized feedstock to a vapor/liquid separator device to produce separate vapor and liquid phases
Implementation Method 2
it is heated and vaporized by indirect contact with hot flue gas from the radiant section of the furnace
Implementation Method 3
Pyrolytic cracking of hydrocarbons is a petrochemical process that is widely used to produce olefins such as ethylene, propylene, butylenes, butadiene
Implementation Method 4
the hydrocarbons are cracked to produce olefins; the cracking conditions in the first set of radiant pyrolysis coils being controlled to achieve a cracking severity
Data Source
AI summary
A process for making lower olefins from a wide boiling range hydrocarbon feed by use of a combination of one or more vapor/liquid separation devices, and then pyrolytically cracking the vapor phase in separate sets of pyrolysis radiant tubes, thereby producing a higher level of lower olefin product.