Raffinate Hydroconversion for High Viscosity Base Stocks
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Solution Overview
Problem
Conventional methods for producing lubricant base stocks, such as catalytic hydroprocessing and solvent processing, face challenges in achieving high yields of high-performance base stocks like Group III and Group II base stocks with desired viscosity indices and sulfur content, often resulting in reduced yields and properties.
Innovation Solution
The raffinate hydroconversion process involves elevated temperature conditions for high conversion of lubricant boiling range feeds, using hydrotreating and hydrocracking under sour or sweet conditions, followed by catalytic dewaxing and hydrofinishing to produce base stocks with enhanced viscosity indices and reduced sulfur content.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If catalytic hydroprocessing is used to generate lubricant base stocks with high viscosity index, then the viscosity index is improved, but the yield of base stocks with heavy neutral or brightstock viscosity is reduced
Solution Approach 1:
The patent applies parameter changes by modifying hydroprocessing conditions (temperature, pressure, catalyst type, residence time) to optimize both viscosity index and yield simultaneously. By adjusting these parameters, the process achieves high viscosity index base stocks while maintaining improved yields compared to conventional methods.
2Temperature
If solvent processing is used to generate lubricant base stocks with high viscosity, then the viscosity is improved, but the base stocks correspond only to Group I with limited performance
Solution Approach 1:
The patent employs composite processing by combining solvent extraction with subsequent hydroprocessing steps. This composite approach transforms solvent-processed raffinate into higher performance Group II and Group III base stocks, achieving both high viscosity and superior performance characteristics that neither method alone can provide.
3Device complexity
If conventional hydroprocessing is used, then the process is simple, but the sulfur content and naphthene content cannot be sufficiently reduced
Solution Approach 1:
The patent segments the hydroprocessing into multiple stages with different functions: a first stage for bulk sulfur and naphthene removal, and a second stage for deep cleaning to achieve ultra-low sulfur and naphthene contents. This segmented approach effectively reduces harmful components while maintaining reasonable process complexity.
4Manufacturing precision
If high conversion is achieved during hydroconversion, then the viscosity index is improved, but the yield of lubricant boiling range products is reduced
Solution Approach 1:
The patent applies partial action by performing hydroconversion to a moderate extent rather than complete conversion. This allows sufficient viscosity index improvement while leaving enough unconverted material to maintain adequate yield of lubricant boiling range products, achieving an optimal balance between quality and quantity.
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 process enables the production of Group III and Group II base stocks with improved viscosity indices and sulfur content, achieving higher yields and enhanced properties compared to conventional methods, while minimizing the content of 3+ ring naphthenes.
Implementation Method 1
The raffinate from solvent extraction is then mildly hydroconverted and dewaxed
Implementation Method 2
performing an elevated amount of feed conversion relative to 370° C. during hydroconversion
Implementation Method 3
additional conversion during catalytic dewaxing of the hydroconverted raffinate
Implementation Method 4
base stocks with a viscosity index of at least 120 and/or a sulfur content of 300 wppm or less
Data Source
AI summary
Systems and methods are provided for production of base stocks with a viscosity index of at least 120 and/or a sulfur content of 300 wppm or less and/or a kinematic viscosity at 100° C. of 3.0 cSt to 8.0 cSt by hydroconversion of a raffinate from aromatic extraction of a feed. The base stocks can further have a reduced content of 3+ ring naphthenes, such as 4.0 wt % or less, or 1.0 wt % or less. The base stocks can be produced by performing an elevated amount of feed conversion relative to 370° C. during hydroconversion of the raffinate, and optionally additional conversion during catalytic dewaxing of the hydroconverted raffinate. The base stocks can optionally be blended with additional base stocks and/or lubricant additives for production of lubricant compositions.