Dual Catalyst System for Ebullated Bed Hydroprocessing
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Solution Overview
Problem
Ebullated bed hydroprocessing systems face limitations in recycling vacuum bottoms due to asphaltene buildup, leading to equipment fouling and reduced quality of final products, especially when processing low-quality heavy oil feedstocks.
Innovation Solution
Implementing a dual catalyst system comprising a solid supported catalyst and well-dispersed metal sulfide catalyst particles in the ebullated bed reactor, allowing for the recycling of vacuum bottoms without asphaltene buildup by forming dispersed metal sulfide catalyst particles in situ, which are then recycled to maintain the asphaltene concentration at or below baseline levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If vacuum bottoms are recycled to increase production of converted products, then productivity increases, but asphaltene buildup occurs causing equipment fouling and reduced reliability
Solution Approach 1:
The harmful asphaltenes are selectively removed from the recycle stream through a deasphalting unit, separating them from the vacuum bottoms before recycling. This allows the beneficial components to be recycled for increased productivity while extracting the harmful asphaltenes that cause fouling and reliability issues.
Solution Approach 2:
A deasphalting unit is introduced as an intermediary between the vacuum distillation and recycling processes. This intermediary unit processes the vacuum bottoms to remove asphaltenes, enabling the recycling of cleaned material without the harmful effects of asphaltene buildup, thus resolving the contradiction between productivity and reliability.
2Productivity
If recycling of vacuum bottoms is implemented to improve throughput, then productivity increases, but product quality deteriorates due to asphaltene accumulation
Solution Approach 1:
Asphaltenes are extracted from the vacuum bottoms through the deasphalting unit before recycling. This removal of harmful components allows high throughput operation while maintaining product quality, as the recycled material no longer contains the asphaltenes that would otherwise accumulate and degrade quality.
Solution Approach 2:
The deasphalting unit serves as an intermediary processing step that enables both high throughput and high quality by removing asphaltenes from the recycle stream. This intermediary function resolves the contradiction between productivity and manufacturing precision.
3Productivity
If higher conversion is pursued to increase productivity, then productivity improves, but equipment fouling worsens due to increased sediment formation
Solution Approach 1:
The deasphalting unit converts the harmful effect of asphaltene-containing vacuum bottoms into a benefit by removing asphaltenes before recycling. This allows higher conversion operations that would otherwise cause excessive fouling, as the cleaned recycle stream no longer contributes to sediment formation, thus converting a harmful factor into a beneficial enabling condition for high productivity.
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 increases the production rate and conversion efficiency of hydrocarbon products, reduces equipment fouling, and maintains or improves the quality of the bottoms product, enabling higher throughput and temperature operation while minimizing shutdowns and maintenance.
Implementation Method 1
adding or forming in situ dispersed metal sulfide catalyst particles in the ebullated bed reactor to yield upgraded ebullated bed reactor with a dual catalyst system comprised of the heterogeneous catalyst and dispersed metal sulfide catalyst particles
Implementation Method 2
subjecting the hydrocarbon products to vacuum distillation and separating distillates from vacuum bottoms containing residual metal sulfide catalyst particles
Data Source
Figure 1
Figure 2A
Figure 2B
AI summary
An ebullated bed hydroprocessing system is upgraded using a dual catalyst system that includes a heterogeneous catalyst and dispersed metal sulfide particles, which permits recycling of vacuum bottoms without recycle buildup of asphaltenes. The dual catalyst system more effectively converts asphaltenes in the ebullated bed reactor and increases asphaltene conversion by an amount that at least offsets higher asphaltene concentration resulting from recycling of vacuum bottoms. In this way, there is no recycle buildup of asphaltenes in upgraded ebullated bed reactor notwithstanding recycling of vacuum bottoms. In addition, residual dispersed metal sulfide catalyst particles in the vacuum bottoms can maintain or increase the concentration of the dispersed metal sulfide catalyst in the ebullated bed reactor.