Two-Stage Heavy Oil Hydroconversion Process
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current processes for converting heavy hydrocarbonaceous fractions of petroleum, particularly those boiling above 1000°F, face challenges in achieving high conversion to stable, high-quality products due to instability and condensation reactions, leading to low-value fuel oil and coke formation, with high investment and operating costs and difficulties in processing metals-rich feedstocks.
Innovation Solution
A two-stage close-coupled thermal-catalytic and catalytic-hydrotreating process is employed, where a mixture of heavy oil feedstock, coal, and dispersed catalyst is converted in a first-stage thermal-catalytic zone, followed by direct passage to a catalytic-hydrotreating zone with inter-zone cooling, utilizing dispersed catalysts to stabilize thermally cracked fragments and reduce heteroatom content, thereby controlling asphaltene condensation and producing high-quality products boiling below 1000°F.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If severe operating conditions are applied to achieve high conversion of heavy oils, then lighter fractions are produced, but thermally cracked fragments and unstable asphaltenes form which undergo condensation reactions to undesirable polycyclic molecules and coke
Solution Approach 1:
The process is divided into two distinct stages: a thermal-catalytic cracking stage followed by a catalytic-hydrotreating stage. This segmentation allows the first stage to focus on breaking down heavy molecules while the second stage专门 handles the removal of unstable asphaltenes and condensation products, preventing coke formation that would occur in a single-stage severe process
Solution Approach 2:
The thermal-catalytic cracking stage performs preliminary breakdown of heavy oil molecules into smaller fragments before the catalytic-hydrotreating stage. This preliminary action creates a more manageable feedstock for the second stage, where heteroatom removal and asphaltene stabilization occur, preventing subsequent condensation reactions
2Productivity
If conventional ebullated bed technologies with solvent de-asphalting are used, then higher liquid conversions are achieved, but the fuel oil product becomes unstable and refractive making further upgrading difficult
Solution Approach 1:
The process employs specific parameter ranges: thermal-catalytic cracking at 700-900°C with 2-10 MPa hydrogen pressure, followed by catalytic-hydrotreating at 300-450°C with 5-20 MPa hydrogen pressure. These controlled parameter changes ensure high liquid conversion while maintaining product stability through proper heteroatom removal and asphaltene saturation
Solution Approach 2:
The process uses composite catalyst systems: metal oxides (Fe2O3, Fe3O4, ZnO, Al2O3, TiO2, SiO2, MgO, CaO, BaO, SrO) in the thermal-catalytic stage combined with sulfided Co-Mo or Ni-Mo catalysts on alumina supports in the hydrotreating stage. This composite approach provides both cracking activity and selective hydroprocessing to produce stable products
3Productivity
If slurry reactor technology with dispersed catalyst systems is used, then conversion is improved, but investment and operating costs increase and product quality remains an issue
Solution Approach 1:
The slurry reactor is divided into two functional zones within a single vessel: an upper thermal-catalytic cracking zone operating at high temperature, and a lower catalytic-hydrotreating zone at moderate temperature. This vertical segmentation allows both high conversion and product quality improvement without requiring separate reactors, reducing equipment complexity
Solution Approach 2:
The process uses hydrogen as an intermediary substance that serves multiple functions: it suppresses unwanted condensation reactions during thermal cracking, provides the reducing atmosphere needed for catalytic hydrotreating, and ultimately saturates aromatic rings and removes heteroatoms to improve product quality
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 achieves high yields of high-quality products with reduced heteroatom content, enhanced stability, and improved processing efficiency, converting at least 50% of heavy oil feedstock above 1000°F to products below 1000°F, with significant reduction in sulfur and nitrogen content, suitable for further upgrading into transportation fuels.
Implementation Method 1
a first-stage thermal-catalytic zone... operated at elevated temperature and pressure... sufficient to convert a significant amount of hydrocarbons in the feedstock boiling above 1000° F. to hydrocarbons boiling below 1000° F.
Implementation Method 2
introducing a mixture comprising heavy oil feedstock, coal and dispersed catalyst particles, into a first-stage thermal-catalytic zone
Implementation Method 3
substantially all of the thermal-catalytic zone gaseous, liquid and solid effluent is passed directly, in a close-coupled manner, into a second stage catalytic-hydrotreating zone with inter-zone cooling to reduce temperature prior to the second stage zone
Implementation Method 4
the first zone effluent is contacted with hydrotreating catalysts under hydrotreating conditions... significant reduction in sulfur and nitrogen content
Implementation Method 5
contacted with hydrotreating catalysts under hydrotreating conditions
Data Source
AI summary
A process for the production of high yields of high quality products from heavy hydrocarbonaceous feedstock comprising a two-stage, close-coupled process, wherein the first stage comprises a thermal-catalytic zone into which is introduced a mixture comprising the feedstock, coal, dispersed catalyst, and hydrogen; and the second, close-coupled stage comprises a catalytic-hydrotreating zone into which substantially all the effluent from the first stage is directly passed and processed under hydrotreating conditions.