Selective Two-Stage Hydroprocessing for Fuel Quality
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current hydrocracking processes face challenges in efficiently producing clean transportation fuels from heavy hydrocarbon feedstocks, as they often result in lower yields and reduced quality due to the retention of aromatics, which affect key properties like smoke point and cetane number.
Innovation Solution
An integrated hydrocracking process that separates the feedstock into aromatic-rich and aromatic-lean fractions, with the aromatic-rich fraction being processed under severe conditions for hydrotreating/hydrocracking and the aromatic-lean fraction under mild conditions, optimizing the hydroprocessing reaction zones for each fraction to improve product quality and yield.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If conventional hydrocracking processes retain aromatics to maintain process simplicity, then device complexity is reduced, but product quality deteriorates due to lower smoke point and cetane number
Solution Approach 1:
The feedstock is separated into aromatic-rich and aromatic-lean fractions through extraction, allowing each fraction to be processed under optimized conditions. The aromatic-rich fraction undergoes severe hydroprocessing to remove nitrogen and sulfur, while the aromatic-lean fraction receives mild hydroprocessing, thereby improving overall product quality without excessive complexity
Solution Approach 2:
Aromatics are extracted from the feedstock using a solvent extraction unit before hydroprocessing. This removal of aromatic compounds, which are responsible for low smoke point and cetane number, enables the production of higher quality transportation fuels while allowing the hydroprocessing units to operate under optimized conditions for each fraction type
2Manufacturing precision
If severe hydroprocessing conditions are applied to all feedstock to remove aromatics, then product quality improves, but productivity decreases due to lower yields
Solution Approach 1:
Different hydroprocessing conditions are applied to different fractions based on their aromatic content. The aromatic-rich fraction receives severe hydroprocessing (higher temperature, pressure, and catalyst activity) to remove nitrogen and sulfur, while the aromatic-lean fraction receives mild hydroprocessing, optimizing both quality and yield for each stream
Solution Approach 2:
The feedstock undergoes preliminary extraction to separate aromatic-rich and aromatic-lean fractions before hydroprocessing. This preliminary separation allows subsequent hydroprocessing units to operate under optimized conditions for each fraction, improving overall yield by avoiding excessive severity on already clean aromatic-lean fractions
3Manufacturing precision
If aromatic-rich fraction is processed separately under optimized conditions, then manufacturing precision improves, but device complexity increases due to additional separation units
Solution Approach 1:
The hydroprocessing system is segmented into two parallel streams: one for aromatic-rich fraction and one for aromatic-lean fraction. Each stream has its own hydroprocessing reactor optimized for its specific feed composition, allowing independent optimization of operating conditions while maintaining overall process integration through a common feed separation and product combining system
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 enhances the yield and quality of middle distillates by targeting and reducing aromatic compounds, specifically nitrogen- and sulfur-containing aromatics, thereby improving the overall efficiency and economics of the hydrocracking process.
Implementation Method 1
the feedstock is separated into an aromatic-rich fraction and an aromatic-lean fraction
Implementation Method 2
the aromatic-rich fraction is passed to a first stage hydroprocessing reaction zone operating under conditions effective to hydrotreat and/or hydrocrack at least a portion of aromatic compounds
Implementation Method 3
hydrotreat and/or hydrocrack at least a portion of aromatic compounds
Implementation Method 4
cracked products, along with partially cracked and unconverted hydrocarbons, are passed to a distillation column for fractionating into products including naphtha, jet fuel/kerosene and diesel
Data Source
AI summary
Aromatic extraction and hydrocracking processes are integrated to optimize the hydrocracking units design and/or performance. By processing aromatic-rich and aromatic-lean fractions separately, the hydrocracking operating severity and or catalyst reactor volume requirement decreases.