Dual-Stage Hydrocracking for Lube Base Stocks
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current refining processes face challenges in producing high-quality lubricating oil base stocks and distillate fuels simultaneously, as they are typically optimized for one type of product, leading to limited yields and degradation of lubricant basestocks due to high recycle ratios and different processing severities required for fuels and lubricants.
Innovation Solution
A process involving two consecutive hydroprocessing steps with separate or combined reactors, where the first step targets heavy oil specifications and the second step targets light oil specifications, allowing for continuous production of high-quality lubricating oil base stocks with middle distillate fuels as by-products, using a divided wall fractionator for product separation and common finishing units for hydrodewaxing and hydrofinishing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a single hydrocracking system is optimized for fuel production with high recycle ratios, then fuel yield is improved, but lube basestock quality deteriorates and lube fraction yield is limited
Solution Approach 1:
The single hydrocracking system is segmented into two separate hydrocracking units: a first hydrocracking unit optimized for lube basestock production with low recycle ratios, and a second hydrocracking unit optimized for fuel production with high recycle ratios. This segmentation allows each unit to operate under optimal conditions for its specific product, resolving the contradiction between fuel yield and lube quality.
2Productivity
If high conversion is applied in hydrocracking to increase fuel production, then fuel yield is improved, but lube basestock performance deteriorates due to excessive conversion and degradation
Solution Approach 1:
The hydrocracking process is segmented into two independent units with different conversion levels. The first unit operates at low conversion specifically for lube basestock to preserve performance indicia, while the second unit operates at high conversion for fuel production. This eliminates the degradation issue caused by high conversion in a single-unit system.
3Quantity of substance
If blocked operation mode is used to produce different lube grades, then optimal yield for each grade is achieved, but transition times and feed segregation requirements increase process complexity
Solution Approach 1:
Instead of using blocked operation with sequential production, the process segments feed streams into two parallel hydrocracking units that simultaneously produce different lube grades. The first unit produces heavy oil lube basestock while the second unit produces light oil lube basestock, eliminating transition times and feed segregation requirements.
Solution Approach 2:
The dual-unit configuration enables continuous simultaneous production of multiple lube grades without interruption. Both units operate continuously in parallel, maintaining steady-state operation and eliminating the transition periods inherent in blocked operation modes.
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 configuration enables the production of high yields of API Group II and Group III lubricating oil base stocks with similar or higher yields than blocked operation modes, eliminating the need for transition times and feed segregation, while maintaining optimal product qualities and reducing capital costs.
Implementation Method 1
The present disclosure relates to a process for converting heavy hydrocarbon oils into high quality lubes with the concomitant production of distillate fuels by hydrocracking
Implementation Method 2
using a divided wall fractionator for product separation
Implementation Method 3
common finishing units for hydrodewaxing and hydrofinishing
Implementation Method 4
common finishing units for hydrodewaxing and hydrofinishing
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A process for producing high yields of higher quality (API Group II, Group III') lubricating oil basestock fractions which allows the production of two or more types of high quality lubes in continuous mode (no blocked operation mode) without transition times and feed or intermediate product tankage segregation. Two consecutive hydroprocessing steps are used: the first step processes a wide cut feed at a severity needed to match heavy oil lube properties. The second step hydroprocesses a light oil after fractionation of the liquid product from the first step at a severity higher than for the heavy oil fraction. The two hydroprocessing steps will normally be carried out in separate reactors but they may be combined in a single reactor which allows for the two fractions to be processed with different degrees of severity.