Vertical Fixed Bed Degasser Temperature Control
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Solution Overview
Problem
Existing degassing methods for polyolefins in vertical fixed bed reactors face challenges in maintaining polymer quality and preventing blockages, as they cannot effectively control the residual polymerization activity and temperature, leading to suboptimal product stability and increased costs due to unconverted monomers and low-volatility compounds.
Innovation Solution
A process for operating a vertical fixed bed degasser involves introducing a stripping gas with 5-60% principal monomer, maintaining temperatures within 20 degrees Celsius of the polymerization reactor temperature, and controlling flowability and density to prevent polymer sintering, ensuring efficient degassing and product stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If prior art degassing conditions are used to favor post-polymerisation in vertical fixed bed degassers, then residual monomer removal is improved, but polymer quality deteriorates and degasser blockage occurs due to melting
Solution Approach 1:
The patent applies parameter changes by precisely controlling temperature (maintaining within ±20°C of polymerization temperature) and stripping gas composition (5-60% monomer content) to achieve effective degassing while preventing polymer melting and maintaining product quality stability
Solution Approach 2:
The patent implements feedback control through continuous monitoring and adjustment of temperature and stripping gas flow rates based on polymer characteristics and residual activity, ensuring optimal degassing conditions are maintained without causing blockages or quality deterioration
2Loss of substance
If higher temperatures are used in degasser to enhance degassing, then residual compound removal is improved, but polymer sintering and blockage increase
Solution Approach 1:
The patent uses parameter changes by optimizing temperature control to maintain it within a narrow range (±20°C of polymerization temperature) rather than using high temperatures, thereby achieving compound removal through controlled stripping while preventing sintering and blockage
Solution Approach 2:
The patent introduces stripping gas as an intermediary medium to facilitate the removal of residual compounds and monomers through mass transfer, eliminating the need for high temperature heating that would cause sintering
3Productivity
If stripping gas with high monomer content is used to enhance post-polymerisation, then residual monomer conversion is improved, but temperature control becomes difficult and blockage risk increases
Solution Approach 1:
The patent applies parameter changes by optimizing stripping gas composition to contain 5-60% monomer and controlling the addition rate to maintain exothermic reaction heat within acceptable limits, thereby achieving effective monomer conversion while maintaining stable temperature control
Solution Approach 2:
The patent uses partial action by introducing monomer-containing stripping gas at controlled rates rather than using pure monomer, achieving sufficient post-polymerisation conversion while preventing excessive heat generation and temperature runaway
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 effectively reduces residual monomers and low-volatility compounds, preventing blockages and maintaining polymer quality, resulting in stable and constant polyolefin production with improved whiteness and reduced environmental impact.
Implementation Method 1
the degassing process comprises the introduction into said degasser of a stripping gas comprising from 5 to 60% by volume of principal monomer
Implementation Method 2
effectively reduces residual monomers and low-volatility compounds
Implementation Method 3
the degassing conditions are selected such that the temperature inside the degasser is maintained within a range of temperatures comprised between the polymerisation reactor temperature plus or minus 20 degrees centigrade
Implementation Method 4
the polymerisation conditions in the degasser are such that there is produced an additional amount of polymer corresponding to between 0.001 and 0.015 times the amount which entered the degasser
Data Source
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AI summary
The present invention relates to a process for operating a vertical fixed bed polymer powder degasser.