POE Solvent Recovery Train for Low-Energy Impurity Separation
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Solution Overview
Problem
Existing polyolefin elastomer (POE) preparation processes face inefficiencies in solvent recovery, particularly with high-purity n-hexane use, leading to high energy consumption and incomplete separation of low-boiling and high-boiling impurities, and require improvements in raw material cost and process operation.
Innovation Solution
A solvent recovery unit (SRU) is introduced, utilizing a mixture of C6 compounds as a solvent, with specific devolatilization and distillation steps to enhance ethylene and 1-octene/1-butene recovery, and incorporating flash and tertiary distillation columns to separate impurities effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high-purity n-hexane is used as a solvent, then the solvent recovery process can proceed, but energy consumption increases significantly due to separation requirements
Solution Approach 1:
The invention changes the solvent composition from high-purity n-hexane to a mixed C6 hydrocarbon solvent system with specific boiling point ranges. This parameter change in solvent composition allows for more efficient separation and reduces the energy required for distillation while maintaining effective solvent recovery rates
Solution Approach 2:
The invention segments the solvent recovery process into multiple distillation stages with different separation objectives. The first distillation column separates light components, the second column separates the C6 solvent, and the third column separates heavy components. This segmentation allows each stage to operate more efficiently, reducing overall energy consumption compared to a single-stage separation process
2Loss of substance
If the entire flow from the first primary devolatilizer is recovered, then material utilization improves, but low-boiling materials like ethane become concentrated causing problems
Solution Approach 1:
The invention segments the recovery flow into different streams based on boiling point characteristics. The first distillation column specifically handles light components (C1-C4 hydrocarbons) that are separated from the main recovery stream. This segmentation prevents concentration of harmful low-boiling impurities while maintaining high material utilization by recovering appropriate fractions
Solution Approach 2:
The invention extracts and removes light components (low-boiling impurities) from the recovery stream before they can concentrate to harmful levels. The first distillation column specifically targets and removes these light hydrocarbons, preventing the harmful concentration effect while still allowing recovery of valuable materials
3Manufacturing precision
If 1-octene is separated from the upper end of the tertiary distillation column, then pure 1-octene is obtained, but materials with lower boiling points than 1-octene and higher than n-hexane cannot be removed
Solution Approach 1:
The invention segments the impurity removal function across three distinct distillation columns, each targeting specific impurity ranges. The first column removes light components, the second column recovers C6 solvent, and the third column separates 1-octene from heavy components. This segmentation ensures that impurities with various boiling points are removed at appropriate stages, achieving complete impurity removal while maintaining 1-octene purity
Solution Approach 2:
The invention introduces intermediate separation stages (first and second distillation columns) that handle specific impurity fractions before the final 1-octene separation. These intermediary columns act as mediators that remove problematic impurities (including those with boiling points between n-hexane and 1-octene) before the final purification stage, ensuring complete impurity removal
4Manufacturing precision
If n-hexane is separated from the upper end of the primary distillation column, then pure solvent is obtained, but a lot of energy is consumed in the process
Solution Approach 1:
The invention segments the n-hexane separation process into a two-stage distillation system. The first distillation column performs preliminary separation and removes light components, while the second distillation column completes the C6 solvent purification. This segmentation reduces the energy burden on any single column by distributing the separation workload, achieving high n-hexane purity with lower overall energy consumption
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 SRU improves solvent and unreacted material recovery rates, reduces energy consumption, and effectively removes low- and high-boiling impurities, optimizing the POE preparation process.
Implementation Method 1
the solvent and the unreacted material are vaporized and discharged during the process through temperature rise and pressure reduction
Implementation Method 2
a primary distillation column which distills secondarily devolatilization circulation flow removed from the secondary devolatilizer and the finisher reaction treatment flow discharged from the water removal process so as to recover flow separated from a middle portion thereof
Data Source
AI summary
The present invention relates to equipment for preparing a polyolefin elastomer including a reactor to which a solvent and a raw material are supplied, a primary devolatilizer which devolatilizes a product discharged from the reactor to remove an unreacted material (primary devolatilization recovery flow), and to discharge the remainder thereof (primary devolatilization preparation flow), a secondary devolatilizer which re-devolatilizes the primary devolatilization preparation flow discharged from the primary devolatilizer to further remove an unreacted material (secondary devolatilization recovery flow), and to discharge the remainder thereof (secondary devolatilization preparation flow), a finisher which scrubs, using water, the secondary devolatilization preparation flow discharged from the secondary devolatilizer, so that the unreacted material and the water are evaporated and a polymer product remains, and a flash drum which removes low-molecular materials (impurity removal flow) from the primary devolatilization recovery flow removed from the primary devolatilizer, and recovers the remainder to the reactor.