Stripping Tower Deasphalting Tar Process
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Solution Overview
Problem
Steam cracked tar, a byproduct of pyrolysis, is incompatible with other refinery products due to its high asphaltene content, limiting its use and requiring either reduced conversion of feedstocks or dilution with higher-value products, which are not economically viable.
Innovation Solution
A process involving a stripping tower where tar is contacted with a stripping agent, such as steam or tail gas, to separate deasphalted tar from asphaltenic heavy tar, making the deasphalted tar compatible with refinery fuel oil pools and allowing the heavy tar to be used in POX or coker units.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If steam cracking is used to produce light olefins, then valuable products are obtained, but steam cracked tar with high asphaltene content is produced which is incompatible with other refinery products
Solution Approach 1:
The invention extracts asphaltenes from steam cracked tar using a deasphalting process with n-heptane as a solvent. The tar is mixed with n-heptane at controlled temperatures and pressures, causing asphaltenes to precipitate and separate from the deasphalted oil. This extraction removes the harmful asphaltene component while preserving the valuable deasphalted tar that can be blended with refinery fuel oils.
Solution Approach 2:
The invention changes physical parameters (temperature, pressure, solvent-to-feed ratio) to control the deasphalting process. By maintaining specific temperature ranges (e.g., 20-50°C) and pressure conditions, and optimizing the n-heptane-to-tar ratio, the process achieves effective asphaltene removal while maintaining economic viability and product compatibility.
2Object-generated harmful factors
If conversion of pyrolysis feed is limited to avoid SCT production, then asphaltene content is reduced, but the amount of valuable light olefin products decreases
Solution Approach 1:
The invention converts the harmful high-asphaltene-content tar into a beneficial product by applying deasphalting treatment. The process transforms what was previously an incompatible waste product into deasphalted tar that can be successfully blended with refinery fuel oils, thereby benefiting from full feed conversion while eliminating the compatibility problem.
3Object-generated harmful factors
If SCT is diluted with stocks that do not contain asphaltenes, then compatibility with refinery products is improved, but higher-value products are consumed
Solution Approach 1:
Instead of diluting tar with valuable asphalten-free stocks, the invention extracts and removes asphaltenes from the tar itself using n-heptane solvent. This produces deasphalted tar that is inherently compatible with refinery fuel oils, eliminating the need to consume higher-value dilution stocks and preserving them for more profitable uses.
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 upgrades tar by achieving at least 50 wt% yield of deasphalted tar, which is compatible with all proportions of refinery fuel oil, and allows the heavy tar bottoms to be utilized in POX or coker units, enhancing the economic value of tar processing.
Implementation Method 1
contacting the tar and a stripping agent in a stripping tower and recovering an overhead comprising deasphalted tar and a heavy tar bottoms product
Implementation Method 2
separate deasphalted tar from asphaltenic heavy tar
Data Source
AI summary
Tar is contacted with stripping agent, such as steam or tail gas, in a stripping tower. A product comprising deasphalted tar is recovered as overheads and a product comprising heavy tar is recovered as bottoms from the stripping tower.