Two-Stage Hydrocracking for Distillate Yield and Lubricant Quality
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current hydrocracking processes face challenges in maximizing diesel yields while maintaining the usability of unconverted higher boiling point hydrocarbons for lubricant applications, often resulting in poor properties and additional processing complexities.
Innovation Solution
A two-stage hydrocracking process with specific catalyst systems and conditions, including a USY and ZSM-48 catalyst mixture, achieves high conversion levels and desirable properties for both converted distillate fuels and unconverted lubricant products, optimizing cetane number, viscosity index, and pour point.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If hydrocracking conversion is increased to maximize diesel yields, then fuel production is improved, but unconverted hydrocarbons deteriorate in quality for lubricant applications
Solution Approach 1:
The hydrocracking process is divided into two distinct stages: a first hydrocracking stage operating at lower conversion (40-70%) to produce diesel and a second hydrocracking stage operating at higher conversion (>70%) to process the unconverted material. This segmentation allows each stage to be optimized for its specific function, resolving the contradiction between maximizing diesel yield and maintaining lubricant quality.
Solution Approach 2:
The process dynamically adjusts operating conditions between two stages: the first stage uses moderate conversion conditions to preserve lubricant quality while producing diesel, and the second stage uses high conversion conditions to maximize diesel yield from the remaining material. This dynamic approach allows the system to achieve both objectives at different times in the process sequence.
2Reliability
If hydrocracking conversion is kept low to maintain unconverted hydrocarbon quality for lubricants, then lubricant properties are improved, but diesel yield is reduced
Solution Approach 1:
The process segments the conversion task: the first stage operates at lower conversion (40-70%) to preserve lubricant quality from the unconverted material, while the second stage operates at higher conversion (>70%) to maximize diesel yield from what remains. This segmentation resolves the contradiction by achieving both quality preservation and yield maximization in sequence.
Solution Approach 2:
The first hydrocracking stage performs a preliminary conversion at moderate levels, producing some diesel while leaving sufficient unconverted material with good lubricant properties. This preliminary action sets up the second stage to then maximize diesel yield from the remaining material, resolving the yield-quality contradiction.
3Reliability
If additional processing steps are added to improve unconverted hydrocarbon properties for lubricant use, then lubricant quality is improved, but process complexity and cost increase
Solution Approach 1:
The two-stage hydrocracking process allows the unconverted material from the first stage to automatically serve as the feed for the second stage, which then converts it to additional diesel. This self-service approach eliminates the need for separate processing steps to handle unconverted material, reducing complexity while improving both diesel yield and lubricant quality.
Solution Approach 2:
The second hydrocracking stage serves multiple functions: it processes the unconverted material from the first stage, maximizes diesel yield, and simultaneously improves the properties of any remaining unconverted material for lubricant use. This multi-functionality eliminates the need for additional dedicated processing steps.
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
The process enhances distillate fuel yields and improves the properties of unconverted hydrocarbons for lubricant use, achieving high conversion levels and specific product characteristics that are commercially valuable.
Implementation Method 1
hydrocracking the vacuum gasoil feedstream in a high-conversion hydrocracking stage with a hydrogen-containing treat gas stream in the presence of a two-stage catalyst system
Implementation Method 2
hydrocracking the vacuum gasoil feedstream in a high-conversion hydrocracking stage with a hydrogen-containing treat gas stream
Data Source
AI summary
This invention relates to a process involving hydrocracking of a feedstream in which a converted fraction can exhibit relatively high distillate product yields and maintained or improved distillate fuel properties, while an unconverted fraction can exhibit improved properties particularly useful in the lubricant area. In this hydrocracking process, it can be advantageous for the yield of converted/unconverted product for gasoline fuel application to be reduced or minimized, relative to converted distillate fuel and unconverted lubricant, Catalysts and conditions can be chosen to assist in attaining, or to optimize, desirable product yields and/or properties.