Hydroprocessing and Visbreaking Integration for Steam Cracker Feed
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Solution Overview
Problem
Current processes for producing olefins from crude or resid-containing fractions are inefficient, as they require extensive processing and result in high capital investments and equipment fouling, with existing methods failing to effectively utilize resid-containing streams in steam cracking.
Innovation Solution
A process integrating hydroprocessing, visbreaking, and thermal cracking to upgrade resid-containing feeds, allowing for the direct use of hydroprocessed resid fractions as steam cracker feedstock, which includes severe hydroprocessing to increase hydrogen saturation and subsequent visbreaking to vaporize and crack undesirable components, thereby producing olefins and aromatic compounds without significant fouling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If resid-containing fractions are directly used as steam cracker feedstock, then capital investments are reduced, but equipment fouling increases and production efficiency decreases
Solution Approach 1:
The patent applies preliminary action by implementing hydroprocessing and visbreaking treatments before the resid-containing fractions enter the steam cracker. These pre-treatment steps remove harmful components that would cause fouling, allowing the use of heavier, cheaper feedstocks without damaging the cracking equipment. The hydroprocessing saturates aromatic rings and removes heteroatoms, while visbreaking breaks down large asphaltene molecules, both preparing the feedstock for successful steam cracking.
Solution Approach 2:
The patent introduces intermediary processing units (hydroprocessor and visbreaker) between the resid feedstock and the steam cracker. These intermediaries transform the problematic resid fractions into suitable feedstock by adding hydrogen and breaking down complex molecules, thereby mediating between the desire to use cheap resid and the need to protect cracker equipment from fouling.
2Reliability
If resid-containing fractions are processed through conventional desalting and fractionation, then feedstock quality is improved, but processing complexity and capital investment increase
Solution Approach 1:
The patent changes the processing parameters by using hydroprocessing conditions (high temperature and pressure with hydrogen) instead of conventional mild hydrotreating, followed by visbreaking at elevated temperatures. These parameter changes enable the direct processing of resid-containing fractions without extensive pre-fractionation, simplifying the overall process while improving feedstock quality for steam cracking.
Solution Approach 2:
The integrated hydroprocessing-visbreaking-steamm cracking system serves multiple functions: it removes heteroatoms, breaks down large molecules, upgrades feedstock quality, and produces olefins and aromatics. This multi-functional approach eliminates the need for separate desalting and fractionation units, reducing processing complexity while maintaining feedstock quality.
3Reliability
If severe hydroprocessing is applied to resid-containing feeds, then hydrogen saturation increases and feedstock quality improves, but processing time and energy consumption increase
Solution Approach 1:
The patent implements continuous useful action by integrating hydroprocessing, visbreaking, and steam cracking in a continuous flow system. The hydroprocessed effluent flows directly to the visbreaker, and the visbroken overhead flows directly to the steam cracker, eliminating interruptions and maximizing the utilization of energy and heat throughout the process. This continuous operation reduces overall energy consumption compared to batch processing with multiple start-stop cycles.
Solution Approach 2:
The patent utilizes thermal expansion and heat integration by using the heat from exothermic hydroprocessing reactions and visbreaking to preheat feedstocks and generate steam for the cracking process. The high temperatures required for visbreaking and steam cracking are partially supplied by the heat released in earlier processing stages, reducing external energy requirements and improving overall energy efficiency.
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 integrated process enhances the production of olefins and aromatic compounds from heavier crudes, reduces capital investments, and minimizes equipment fouling by effectively processing resid-containing streams, achieving higher petrochemical yields and reducing tar and coke production.
Implementation Method 1
severe hydroprocessing to increase hydrogen saturation
Implementation Method 2
heated and vaporized by indirect contact with hot flue gas
Implementation Method 3
subsequent visbreaking to vaporize and crack undesirable components
Implementation Method 4
thermal cracking of the feedstream
Implementation Method 5
quickly heated, at pressures typically ranging from about 10 to about 30 psig, to a severe hydrocarbon cracking temperature, such as in the range of from about 1450° F. (788° C.) to about 1550° F. (843° C.), to provide thorough thermal cracking of the feedstream
Implementation Method 6
heated and vaporized by indirect contact with hot flue gas from the radiant section
Data Source
AI summary
The invention concerns integration of hydroprocessing and steam cracking. A feed comprising crude or resid-containing fraction thereof is treated by hydroprocessing and visbreaking and then passed to a steam cracker to obtain a product comprising olefins.