Hydrocarbon Utility Fluid for Pyrolysis Tar Hydroprocessing
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Solution Overview
Problem
The hydroprocessing of pyrolysis tar, particularly steam-cracker tar, leads to significant catalyst deactivation due to the presence of 'Tar Heavies' (TH), resulting in decreased efficiency and increased formation of undesirable deposits, requiring additional utility fluids to prevent reactor fouling, which are often valuable and costly.
Innovation Solution
A hydrocarbon-containing fluid with specific properties, such as a solubility blending number of 90 or more, density of 0.98 g/cm3 or less, and low bromine number, is used as a supplemental utility fluid, derived from catalytic reforming processes, to facilitate tar hydroprocessing, reducing the need for conventional utility fluids and minimizing ring loss and saturation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If conventional utility fluids are used to hydroprocess pyrolysis tar, then deposit formation on catalyst is reduced, but the cost increases due to loss of valuable supplemental utility fluids
Solution Approach 1:
The patent changes the compositional parameters of the utility fluid by specifying a particular range of aromatic hydrocarbons (including compounds with 2-4 aromatic rings) and controlling the solubility blending number to be at least 85. This optimized composition reduces deposit formation on catalyst while minimizing the need for supplemental utility fluids, thereby resolving the contradiction between reducing harmful deposits and preventing loss of valuable fluids.
2Productivity
If supplemental utility fluid is added to prevent reactor fouling, then hydroprocessing efficiency is maintained, but the process complexity and cost increase
Solution Approach 1:
The patent enables the hydroprocessing system to be self-sufficient by formulating the utility fluid with an appropriate mix of aromatic hydrocarbons that naturally prevent catalyst deactivation and reactor fouling. This self-service approach eliminates the need for additional supplemental utility fluid additions, maintaining hydroprocessing efficiency while simplifying the overall process and reducing operational complexity.
3Quantity of substance
If recycled liquid phase components are used as utility fluid, then valuable products are utilized, but the utility fluid quality degrades over time requiring supplemental fluid addition
Solution Approach 1:
The patent specifies precise compositional parameters for the utility fluid, including the presence of aromatic hydrocarbons with 2-4 rings and a solubility blending number of at least 85. This controlled composition maintains fluid quality stability even when using recycled liquid phase components, preventing degradation and eliminating the need for supplemental fluid addition while still utilizing valuable recycled products.
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 hydrocarbon-containing fluid effectively maintains desirable compositional profiles, reduces the time to achieve steady-state conditions, and decreases the amount of ring loss, thereby improving the hydroprocessing efficiency and reducing the need for costly supplemental fluids.
Implementation Method 1
combining (i) a tar feed and (ii) a hydrocarbon-containing fluid
Implementation Method 2
hydroprocessing pyrolysis tar in the presence of a hydrogen-containing treat gas and at least one hydroprocessing catalyst produces an upgraded pyrolysis tar
Implementation Method 3
hydroprocessing the SCT in the presence of a utility fluid produces fewer undesirable byproducts
Data Source
AI summary
Hydrocarbon-containing fluids are provided for use during solvent-assisted hydroprocessing of pyrolysis tar, such as steam cracker tar. The hydrocarbon-containing fluids can be used at any convenient time, such as during start-up of a pyrolysis process when recycled liquid pyrolysis product is not available; when the amount of liquid pyrolysis product available for recycle is not sufficient to maintain desired hydroprocessing conditions; and/or when the changes to the quality of the liquid pyrolysis product reduce the suitability of the recycle stream for use as a utility fluid.