Polymer Devolatilization via Phase Separator and Pressure Letdown
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Solution Overview
Problem
Current devolatilization processes for polymers face challenges such as high energy consumption, polymer degradation, and extended transition times between polymer grades due to the use of large heat exchangers and recycle lines, leading to increased production costs and off-spec material.
Innovation Solution
A process and plant design that involves a polymerization reactor coupled with a phase separator, a heat exchanger, and a pressure letdown valve, where the reactor effluent is mixed with a concentrated polymer solution and then heated before being introduced to the phase separator, reducing the need for high-temperature heat exchange and minimizing polymer degradation, and allowing for reduced recycle line quantities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional devolatilization processes use large heat exchangers and recycle lines to remove volatiles from polymer, then volatile removal is achieved, but energy consumption increases and polymer degradation occurs
Solution Approach 1:
The invention utilizes phase transition by introducing reactor effluent to a phase separator where pressure is reduced, causing volatile components to separate from the polymer solution as a distinct vapor phase. This eliminates the need for high-temperature heat exchange and recycle lines, thereby reducing energy consumption while preventing polymer degradation.
Solution Approach 2:
The invention extracts volatile components from the polymer solution by introducing the effluent to a phase separator operating at reduced pressure. The volatiles are removed as a separate vapor stream, eliminating the need for conventional heat exchangers and recycle lines that cause energy loss and polymer degradation.
2Productivity
If conventional processes use recycle lines to return concentrated polymer to the devolatilization vessel, then devolatilization efficiency is improved, but transition time between polymer grades increases
Solution Approach 1:
The invention extracts volatiles directly from the reactor effluent in a phase separator before the polymer enters any recycle system. By removing volatiles upfront and eliminating the need for recycle lines, the system achieves efficient devolatilization without the time penalty of cycling polymer through large recycle lines during grade transitions.
Solution Approach 2:
Instead of using recycle lines to return polymer to the devolatilization vessel as in conventional processes, the invention inverts the approach by performing devolatilization in a phase separator that receives effluent directly from the reactor. This eliminates the recycle loop entirely, reducing transition time between grades while maintaining devolatilization efficiency.
3Quantity of substance
If heat exchangers operate at high temperatures to enable devolatilization, then volatile removal is enhanced, but polymer degradation and fouling increase
Solution Approach 1:
The invention employs phase transition by reducing pressure in the phase separator, which lowers the boiling point of volatile components. This allows volatiles to be removed at lower temperatures through vapor-liquid equilibrium, enhancing volatile removal while preventing polymer degradation and fouling that would occur at high temperatures.
Solution Approach 2:
The invention converts the harmful effect of high temperature requirements for devolatilization into a benefit by using pressure reduction instead. The phase separator utilizes reduced pressure to enable volatile removal at low temperatures, transforming what would be a harmful high-temperature process into a benign low-temperature operation that prevents polymer degradation.
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 reduces the amount of off-spec material, decreases transition time between polymer grades, and minimizes the amount of recycled polymer in the recycle line, resulting in more efficient and cost-effective polymer production with improved polymer quality.
Implementation Method 1
introducing the mixture to a heat exchanger to form a heated mixture
Implementation Method 2
introducing the heated mixture to a phase separator. The process includes removing a second concentrated polymer solution from the phase separator
Data Source
AI summary
The present disclosure relates to plants and processes for forming polymers. In some embodiments, a process of forming a polymer includes supplying a. feed having one or more olefin monomers and a solvent. The process includes introducing the feed with a catalyst to form a reaction mixture in a reactor. The process includes moving a. reactor effluent from the reactor and comingling, in a mixer or in a line, the reactor effluent with a first concentrated polymer solution to form a mixture. The process includes introducing the mixture to a heat exchanger to form a heated mixture and introducing the heated mixture to a pressure let down valve followed by introducing the heated mixture to a phase separator. The process includes removing a second concentrated polymer solution from the phase separator. The process includes introducing the second concentrated, polymer solution to the mixer or the line.