Pyrolysis Tar Particle Size Reduction for Hydroprocessing
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Solution Overview
Problem
Steam cracking processes produce steam cracked tar (SCT) with high molecular weight materials that are difficult to process due to the presence of particulates, leading to fouling and plugging in catalyst beds, and result in low compatibility with other products, limiting the production of higher value hydrocarbon products.
Innovation Solution
Implementing mechanical size reduction processes, such as grinding or ball milling, in combination with separation techniques like centrifugation to reduce the particle size of SCT, allowing for the effective hydroprocessing of smaller particles and minimizing fouling in catalyst beds, thereby increasing the yield of hydrocarbon products.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If mechanical size reduction processes are applied to pyrolysis tar, then particle size is reduced and hydroprocessing efficiency is improved, but device complexity and process steps increase
Solution Approach 1:
The patent applies mechanical size reduction processes (grinding, ball milling, or ablation) before hydroprocessing to pre-treat the pyrolysis tar and reduce particle size. This preliminary action converts difficult-to-process large particles into smaller particles that are more amenable to hydroprocessing, thereby improving subsequent hydroprocessing efficiency without requiring fundamental changes to the hydroprocessing unit itself.
2Reliability
If larger particles are removed from pyrolysis tar, then fouling and plugging in catalyst beds is reduced, but loss of valuable material increases
Solution Approach 1:
The patent changes the particle size parameter of the pyrolysis tar through mechanical size reduction processes. By converting large particles into smaller particles, the material properties are altered to improve compatibility with hydroprocessing conditions. This allows previously unusable large particles to be converted into processable material, reducing both fouling issues and valuable material loss.
3Productivity
If the proportion of pyrolysis tar processed is increased, then production of higher value products is improved, but fouling and plugging problems worsen
Solution Approach 1:
The patent replaces the conventional approach of mechanically removing particles with a mechanical size reduction process that converts large particles into smaller particles chemically and physically. This substitution transforms the problem from particle removal to particle conversion, allowing a higher proportion of pyrolysis tar to be processed while minimizing fouling and plugging in catalyst beds.
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 converts larger particles into smaller ones, enhancing the hydroprocessing efficiency of SCT, reducing fouling and plugging, and increasing the proportion of SCT that can be processed into higher value products, while minimizing waste streams.
Implementation Method 1
A combination of separation processes, such as centrifugation, and mechanical or physical size reduction
Implementation Method 2
mechanical or physical size reduction, such as grinding, ball milling, or ablation
Implementation Method 3
hydroprocessing can be effective for removal of particles (such as coke particles) that have a size below 50 μm
Data Source
AI summary
Systems and methods are provided for increasing the portion of a pyrolysis tar fraction that can be hydroprocessed by using a physical particle size reduction process on at least a portion of the pyrolysis tar fraction. The physical particle size reduction process can reduce the percentage of particles in the pyrolysis tar fraction that have a particle size of 75 μm or greater, or 50 μm or greater. It has been unexpectedly discovered that at least a portion of the particles having a size of 75 μm or less, or 50 μm or less, can be effectively hydroprocessed to form products of greater value while still reducing or minimizing the amount of fouling or plugging in a hydroprocessing catalyst bed. By increasing the number of particles having a size of 75 μm or less, or 50 μm or less, while selectively removing larger particles from the SCT fraction, a higher yield of hydrocarbon products can be achieved for a feed containing an SCT fraction. This can reduce or minimize the amount of particulates that are disposed of by incineration or another disposal method for fractions that have a lesser value.