Butadiene Extraction Tar Control via Solvent Reclamation
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Solution Overview
Problem
The existing solvent extraction processes for butadiene from hydrocarbon mixtures face challenges in controlling tar formation and deposition, which leads to equipment plugging and increased maintenance costs, despite maintaining high tar levels as per industry standards.
Innovation Solution
Maintaining tar levels below 1.6 wt.% in the solvent mixture and reducing the total tar and secondary solvent content to less than 5 wt.% in the butadiene extraction system, achieved through alterations in the solvent reclamation system, including cooling the secondary solvent stream before injection and altering the solvent reclamation unit operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high tar levels (not less than 2 wt.%) are maintained in the solvent mixture as per industry standards, then tar formation control is supposed to be achieved, but tar deposition and equipment plugging actually increase
Solution Approach 1:
The patent changes the critical parameter of tar content from the conventional minimum 2 wt.% to a maximum of less than 1.6 wt.%. This parameter inversion resolves the contradiction by demonstrating that lower tar levels, contrary to industry dogma, actually prevent tar deposition and equipment plugging while maintaining reliable operation.
Solution Approach 2:
The patent applies inversion by completely reversing the conventional approach: instead of maintaining high tar levels to control tar formation, it maintains low tar levels to achieve the same effect. This inverted approach breaks the harmful cycle where high tar levels lead to more deposition.
2Ease of operation
If tar level is maintained at not less than 2 wt.% and total tar plus secondary solvent at 5 wt.%, then operating specifications are met, but equipment requires frequent shutdown and clean out
Solution Approach 1:
The patent changes the operating parameters from the conventional tar level of 2-5 wt.% to a reduced level of less than 1.6 wt.%. This parameter change eliminates the need for frequent maintenance shutdowns while still meeting operational requirements, thereby reducing time loss without sacrificing ease of operation.
Solution Approach 2:
By maintaining low tar levels, the system becomes self-cleaning and resistant to tar deposition, reducing the need for external maintenance interventions and shutdowns. The process naturally prevents tar accumulation rather than requiring periodic cleanup.
3Loss of substance
If conventional solvent reclamation operation is used, then solvent is recovered, but tar accumulates and causes deposition in equipment
Solution Approach 1:
The patent modifies the solvent reclamation operation by changing the parameter of tar content from accepting conventional levels to actively maintaining levels below 1.6 wt.%. This change prevents tar accumulation during solvent recovery while still achieving effective solvent reuse.
Solution Approach 2:
The patent implements feedback control in the solvent reclamation system by monitoring and adjusting tar levels to maintain them below the 1.6 wt.% threshold. This feedback mechanism ensures that solvent recovery operations do not lead to tar accumulation that would cause equipment deposition.
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 results in a self-cleaning extraction system with reduced tar formation and deposition, increased operational time between maintenance shutdowns, lower energy costs, and reduced solvent loss, effectively addressing the tar-related issues in butadiene extraction.
Implementation Method 1
a primary solvent and a secondary solvent which, when mixed together, form a solvent mixture that is effective for the extraction of butadiene from a crude C4 stream
Implementation Method 2
maintaining the level of tars in the solvent mixture circulating in the system at not greater than about 1.6 wt. %
Data Source
AI summary
In a method for the solvent extraction of butadiene from a mixture of hydrocarbons having four carbon atoms per molecule, which method inherently produces tars, the extraction process is operated with a tar loading level, relative to the solvent employed, of no more than about 1.6 wt. %.