Two-Stage Hydrotreating for Lubricant Base Oil and Fuel
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Solution Overview
Problem
Current processes for upgrading heavy oils to meet demand face challenges in efficiently recovering heavier hydrocarbons from vacuum residue, leading to conflicts between deasphalted oil production and desired lubricant base oil viscosity, making solvent deasphalting (SDA) units uneconomic for residue upgrading.
Innovation Solution
A two-stage hydrotreating process is employed, where the deasphalted oil and vacuum gas oil are hydroprocessed in a first stage, and the unconverted product is further processed in a second stage, with effluents combined for efficient separation and recovery of fuel range hydrocarbons and lubricant base oils, allowing for upgrading of unconverted oil streams in a dewaxing zone.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If solvent deasphalting is used to convert vacuum residue to deasphalted oil, then heavier hydrocarbons are recovered, but the amount of deasphalted oil produced conflicts with the desired lube base oil viscosity
Solution Approach 1:
The patent divides the hydroprocessing into two distinct stages: first stage hydroprocessing for initial conversion and second stage hydroprocessing for further conversion of unconverted oil. This segmentation allows independent optimization of each stage to simultaneously achieve high deasphalted oil yield and precise lube base oil viscosity control
Solution Approach 2:
The patent implements dynamic process control by using a recycle stream where unconverted oil from the first stage is fed to the second stage, and by adjusting operating parameters (temperature, pressure, catalyst) in each stage to dynamically balance between maximizing deasphalted oil production and achieving target lube viscosity grades
2Quantity of substance
If deasphalted oil is processed for lube base oil production, then lube products are obtained, but overall refinery conversion decreases
Solution Approach 1:
The patent changes the processing parameters between stages: first stage uses conditions optimized for conversion (higher severity) while second stage uses conditions optimized for lube quality (lower severity). This parameter optimization allows maximum fuel range hydrocarbon production while still achieving high lube base oil yields from the unconverted oil
Solution Approach 2:
The patent maintains continuous useful action by recycling unconverted oil from the first stage to the second stage, ensuring that all feedstock is fully utilized. This continuous processing maximizes overall refinery conversion by converting both the deasphalted oil and the unconverted oil fractions into valuable products
3Quantity of substance
If heavier hydrocarbons are recovered from vacuum residue, then fuel range products are produced, but separation and recovery efficiency decreases
Solution Approach 1:
The patent performs preliminary hydroprocessing of the deasphalted oil before final separation, which pre-treats the feedstock and simplifies subsequent separation steps. This preliminary conversion of heavy hydrocarbons into lighter fractions before separation significantly improves separation efficiency and fuel range hydrocarbon recovery
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 enables efficient production of fuel range hydrocarbons and lubricant base oils, allowing refiners to control production based on product desirability, making SDA units more feasible and economic by optimizing hydrocarbon recovery and viscosity grades.
Implementation Method 1
SDA processes separate hydrocarbons according to their solubility in a liquid solvent
Implementation Method 2
hydroprocessing the deasphalted oil stream in a first hydroprocessing zone; hydroprocessing a vacuum gas oil stream in the first hydroprocessing zone
Implementation Method 3
hydroprocessing the recycle stream in a second hydroprocessing zone
Implementation Method 4
separating an effluent stream from the first hydroprocessing zone in a second separation zone into a fuel range hydrocarbon stream and an unconverted oil stream
Implementation Method 5
separating the unconverted oil stream in a third separation zone into one or more lubricant base oil streams and a recycle stream
Data Source
AI summary
Apparatuses and processes for producing at least one lubricant base oil and at least one hydrocarbon fuel range product. A deasphalted oil and a VGO stream and passed to a first hydroprocessing zone. After the first hydroprocessing zone, the hydrocarbon fuel range product may be recovered. After recovering the hydrocarbon fuel range product, the unconverted material may be separated into one or more lubricant base oil streams, and a recycle stream. The lubricant base oil streams may be upgraded, while the recycle stream may be hydroprocessed in a second hydroprocessing zone. The effluents can be combined to allow for efficient separation and recovery of the desired products.