Multi-Stage Hydroconversion for Heavy Feedstocks
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Solution Overview
Problem
Conventional hydroconversion processes for heavy hydrocarbon feeds face limitations in achieving high conversion levels due to the formation of sediments and catalyst deactivation, which restrict operability and require additional steps like deasphalting, increasing costs and complexity.
Innovation Solution
A process involving multiple stages of hydroconversion in three-phase reactors with specific catalysts and optimized thermal and residence time conditions, using alumina-supported nickel and molybdenum catalysts, and optional separation steps to improve conversion and stability of liquid effluents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the severity of hydroconversion operation is increased to improve conversion of heavy cuts to light products, then conversion level is improved, but formation of sediments and catalyst deactivation increases
Solution Approach 1:
The hydroconversion process is divided into multiple stages with different severity levels. The first stage operates under moderate conditions to perform initial conversion while limiting sediment formation. The second stage then processes the effluent from the first stage under optimized conditions to achieve further conversion. This segmentation allows the system to achieve high overall conversion without subjecting the catalyst to excessively severe conditions that would cause rapid deactivation and sediment precipitation.
Solution Approach 2:
The first hydroconversion stage acts as a preliminary treatment step that performs initial conversion of heavy cuts and modifies the feed composition before it enters the second stage. This preliminary action reduces the burden on the second stage catalyst, allowing it to operate under more favorable conditions that minimize sediment formation and catalyst deactivation while still achieving high overall conversion.
2Productivity
If extensive conversion of heavy cuts is performed to increase light product yield, then productivity is improved, but formation of coke precursors and sediments increases leading to equipment clogging
Solution Approach 1:
The conversion process is segmented into two stages with different operating characteristics. The first stage operates under moderate severity to perform initial conversion while limiting coke and sediment formation. The second stage then processes the modified effluent under optimized conditions to achieve further conversion to light products. This segmentation allows high overall conversion and light product yield while controlling harmful sediment and coke formation at each stage.
Solution Approach 2:
The process utilizes changes in operating parameters between stages. The first stage operates with specific temperature, pressure, and space velocity parameters that favor conversion while limiting side reactions. The second stage uses different optimized parameters to achieve further conversion of the effluent from the first stage. These parameter changes allow the system to maximize light product yield while minimizing sediment and coke formation.
3Productivity
If additional deasphalting steps are added to overcome operability limits, then conversion level is improved, but device complexity and processing costs increase
Solution Approach 1:
The invention merges two hydroconversion stages into a unified process configuration where the effluent from the first stage is directly fed to the second stage. This integrated approach eliminates the need for separate deasphalting units and associated equipment that would be required in conventional single-stage or deasphalting-based processes. The merging of functions achieves high conversion levels while maintaining simpler device complexity and lower processing costs.
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 enhances the conversion level and stability of liquid effluents, reducing sediment formation and catalyst deactivation, thereby improving the operational efficiency and reducing the need for additional processing steps.
Implementation Method 1
a) a step of hydroconversion of the heavy hydrocarbon feed in the presence of hydrogen in at least one or more three-phase reactors arranged in series or in parallel, containing at least one hydroconversion catalyst
Implementation Method 2
at least one or more three-phase reactors arranged in series or in parallel
Implementation Method 3
These refined products generally have a higher hydrogen to carbon ratio than the starting heavy cuts. A series of processes used to produce refined light cuts, such as hydrocracking, hydrotreating and hydroconversion processes, are therefore based on the addition of hydrogen into the molecules
Data Source
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AI summary
The invention relates to a method for converting a heavy hydrocarbon feedstock, said method comprising the following steps: a) a step of hydroconverting the heavy hydrocarbon feedstock in the presence of hydrogen in at least one or more three-phase reactors arranged in series or parallel, containing at least one hydroconversion catalyst, in such a way as to obtain a liquid effluent with a reduced content of Conradson carbon, metals, sulfur and nitrogen; b) one or more optional steps of separating the effluent from step a) in order to to obtain at least one light liquid fraction, boiling at a temperature of less than 350°C, and one heavy liquid fraction, boiling at a temperature greater than 350°C; c) a hydroconversion step of the liquid effluent from hydroconversion step a), in the case where separation step b) is not implemented, or of the heavy liquid fraction coming from separation step b), when said step b) is implemented, in the presence of hydrogen in at least one or more three-phase reactors arranged in series or in parallel and containing at least one hydroconversion catalyst, process in which the overall hourly space velocity implemented is between 0.05 and 0.18 h-1.