Hydroprocessing Tar Heavies with Aromatic Solvent
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional SCT hydroprocessing is plagued by catalyst coking, which is exacerbated by high hydrogen partial pressures and temperatures, leading to undesirable hydrogenation reactions and increased costs, while also resulting in significant conversion of tar to coke, reducing the efficiency and economic viability of the process.
Innovation Solution
The process involves hydroprocessing SCT in the presence of a utility fluid rich in aromatics, which breaks down Tar Heavies into smaller, more mobile molecules, allowing for lower pressure operation and reduced coke yield, thereby improving catalyst longevity and process economics by minimizing coke formation and maintaining the desired hydrocracking reaction over aromatics hydrogenation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional SCT hydroprocessing is operated at elevated hydrogen partial pressure to lessen catalyst coking, then catalyst coking is reduced, but hydrogen consumption and equipment costs increase significantly
Solution Approach 1:
A solvent is introduced as an intermediary substance that mediates between the SCT feed and catalyst. The solvent preferentially solvates and disperses Tar Heavies and coke precursors, preventing their deposition on the catalyst surface. This allows effective hydroprocessing at lower hydrogen partial pressures, resolving the contradiction between catalyst protection and hydrogen consumption.
Solution Approach 2:
The process changes the chemical environment parameters by introducing a solvent that alters the solubility and reactivity of Tar Heavies. This parameter change enables the system to achieve acceptable catalyst performance at reduced hydrogen partial pressure, thereby reducing hydrogen consumption while maintaining catalyst activity.
2Reliability
If conventional SCT hydroprocessing operates at reduced temperature (200-350°C) to lessen catalyst coking, then catalyst coking is reduced, but undesired hydrogenation reactions are favored and process economics worsen
Solution Approach 1:
The solvent acts as a mediator that enables selective interaction with Tar Heavies, allowing the process to operate at higher temperatures that favor hydrocracking while the solvent simultaneously prevents catalyst coking by solvating coke precursors. This resolves the contradiction between temperature-dependent hydrocracking efficiency and catalyst protection.
3Reliability
If conventional SCT hydroprocessing uses diminished space velocity to reduce catalyst coking, then catalyst coking is lessened, but process productivity and efficiency decrease
Solution Approach 1:
The solvent intermediary protects the catalyst from coking by solvating Tar Heavies, enabling the system to maintain high space velocities (shorter contact times) without sacrificing catalyst life. This resolves the contradiction between catalyst protection and process throughput.
4Quantity of substance
If SCT contains high molecular weight Tar Heavies with low mobility, then the feed is more challenging to process, but mass transport limitations reduce hydrocracking reaction efficiency
Solution Approach 1:
The solvent serves as an intermediary that solvates high molecular weight Tar Heavies, increasing their apparent mobility and accessibility to catalyst active sites. This enhances mass transport and hydrocracking efficiency without requiring changes to the Tar Heavies composition itself.
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 significantly reduces coke yield to less than 0.1 wt.%, extends catalyst life, and maintains the production of light hydrocarbons, thereby improving the overall efficiency and cost-effectiveness of the hydroprocessing stage by allowing operation at lower pressures and preventing over-cracking of SCT.
Implementation Method 1
combining the separated Tar Heavies with a utility fluid comprising a significant amount of aromatics
Implementation Method 2
contacting the third mixture with at least one hydroprocessing catalyst under catalytic hydroprocessing conditions to convert at least a portion of the third mixture to a hydroprocessed product
Implementation Method 3
contacting the third mixture with at least one hydroprocessing catalyst under catalytic hydroprocessing conditions in the presence of molecular hydrogen
Implementation Method 4
exposing the first mixture to a temperature ≧400° C. under pyrolysis conditions to produce a second mixture
Data Source
AI summary
The invention relates to upgraded pyrolysis products, processes for upgrading products obtained from hydrocarbon pyrolysis, equipment useful for such processes, and the use of upgraded pyrolysis products.