Multi-Stage Hydroprocessing Pyrolysis Tar
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Solution Overview
Problem
Current hydroprocessing methods for pyrolysis tars face challenges in producing upgraded tar products suitable for fuel oil blendstocks without compromising reactor lifetime, particularly in reducing sulfur content, viscosity, and preventing fouling, especially when blending with marine fuel oil.
Innovation Solution
A multi-stage hydroprocessing process that separates pyrolysis tar into at least two zones, utilizing a utility fluid with aromatic compounds to produce hydroprocessed products with lower sulfur content, higher aromaticity, and reduced viscosity, which can be used as low sulfur fuel oil (LSFO) or ultra low sulfur fuel oil (ULSFO) blendstocks, and blends with gas oil to lower its pour point.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If hydroprocessing is carried out at conventional conditions with single-stage process, then sulfur content is reduced, but catalyst coking occurs and reactor lifetime is compromised
Solution Approach 1:
The hydroprocessing operation is divided into two distinct stages: a first stage operating at lower severity conditions and a second stage operating at higher severity conditions. This segmentation allows the process to achieve thorough sulfur removal while preventing excessive coking that would occur in a single high-severity stage, thereby extending catalyst and reactor lifetime.
Solution Approach 2:
The process employs parameter changes by operating the first hydroprocessing stage at lower temperature and pressure conditions compared to the second stage. This progressive parameter adjustment enables controlled sulfur removal in the first stage, followed by more intensive treatment in the second stage, optimizing both sulfur reduction and reactor longevity.
2Force
If hydroprocessing is carried out at higher severity to reduce viscosity, then viscosity is reduced, but fouling of process equipment increases
Solution Approach 1:
Viscosity reduction is achieved through segmented hydroprocessing stages rather than a single high-severity stage. The first stage performs mild hydroprocessing that begins viscosity reduction without generating excessive fouling, while the second stage completes the viscosity reduction with more severe conditions on already-stabilized feed, minimizing overall fouling.
Solution Approach 2:
The first hydroprocessing stage performs preliminary action by conducting initial treatment at lower severity conditions, removing some sulfur and beginning viscosity reduction before the feed enters the second stage. This preliminary action stabilizes the feed and reduces the fouling potential for the subsequent high-severity second stage.
3Manufacturing precision
If multi-stage hydroprocessing is implemented, then product quality is improved, but process complexity increases
Solution Approach 1:
The process uses segmentation into two hydroprocessing stages, each with optimized conditions for specific product quality attributes. The first stage focuses on sulfur removal with milder conditions, while the second stage targets viscosity reduction and final product specification with more severe conditions, achieving superior product quality through systematic division of tasks.
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
The process effectively produces hydroprocessed products with desirable properties for use as LSFO or ULSFO, enhancing compatibility with marine fuel oil and reducing the risk of fouling, while maintaining energy content and viscosity, thus extending reactor life and improving fuel oil blending capabilities.
Implementation Method 1
utilizing a utility fluid with aromatic compounds to produce hydroprocessed products
Implementation Method 2
multi-stage hydroprocessing process that separates pyrolysis tar into at least two zones
Data Source
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AI summary
A first hydroprocessed product and a second hydroprocessed product produced from a multi-stage process for upgrading pyrolysis tar, such as steam cracker tar, are provided herein. Fuel blends including the first hydroprocessed product and/or the second hydroprocessed product are also provided herein as well as methods of lowering pour point of a gas oil using the first hydroprocessed product and the second hydroprocessed product.