Multistage Gas-Phase Polymer Transfer With Recycled Compressed Gas
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Solution Overview
Problem
Existing gas phase polymerization processes face challenges in efficiently transferring polymers between reactors while minimizing gas entrainment, which can lead to waste flaring, quality issues, and safety risks, and require costly and energy-intensive gas management to maintain reactor-specific compositions.
Innovation Solution
A process involving continuous or intermittent withdrawal and redirection of reaction gas mixtures between consecutive gas phase reactors, using compressed gas from downstream reactors to facilitate polymer transfer and maintain controlled gas exchange, reducing equipment and energy costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If gas phase polymerization reactors are used with outlet vessels to transfer polymer between reactors, then polymer production flexibility and catalyst versatility are improved, but gas entrainment in polymer powder increases leading to waste flaring and quality problems
Solution Approach 1:
The invention extracts and removes the gas mixture from the polymer powder in the outlet vessel by applying a vacuum. This separates the harmful gas entrainment from the polymer product, allowing the gas to be recovered and reused while the polymer is transferred to the next reactor with minimal gas content.
Solution Approach 2:
The invention changes the pressure parameter in the outlet vessel by applying vacuum conditions. This pressure change causes the gas mixture to be removed from the polymer powder, reducing gas entrainment while maintaining the ability to transfer polymer between reactors operating at different pressures.
2Manufacturing precision
If gas mixture entrainment is reduced through conventional means, then polymer quality is improved, but equipment complexity and energy consumption increase
Solution Approach 1:
The outlet vessel itself serves the dual function of polymer transfer and gas removal. By applying vacuum to the outlet vessel, the system uses the existing vessel structure to perform gas separation, eliminating the need for separate complex gas management equipment while improving polymer quality.
3Productivity
If transfer lines are used to move polymer between reactors, then continuous production is maintained, but malfunction or plugging can occur causing productivity loss and safety risks
Solution Approach 1:
The invention extracts polymer from the gas phase environment in the outlet vessel and transfers it as solid particles or in a controlled manner to the next reactor. This separation of polymer transfer from gas flow reduces the risk of transfer line plugging and malfunction while maintaining continuous production.
4Productivity
If reactor pressure is maintained for efficient polymerization, then reaction efficiency is improved, but gas management complexity increases when transferring between reactors at different pressures
Solution Approach 1:
The outlet vessel performs multiple functions: it serves as the transfer point between reactors at different pressures, maintains vacuum for gas removal, and enables pressure equalization. This multi-functionality simplifies the overall pressure control system while allowing efficient polymerization at optimal pressures in each reactor.
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 enables the production of multimodal olefin polymers with tailored properties, enhances catalyst productivity, and minimizes process disturbances, achieving lower investment and operating costs while ensuring consistent polymer quality.
Implementation Method 1
unreacted gas withdrawn from said second gas phase polymerization reactor is compressed in a compressor and said compressed gas is fed into an outlet between said first outlet vessel and said second gas phase polymerization reactor
Implementation Method 2
unreacted gas withdrawn from said second gas phase polymerization reactor is compressed in a compressor
Data Source
AI summary
The present invention relates to a process for producing alpha-olefin polymers in a multistage polymerization process which includes at least two gas phase polymerization reactors, wherein unreacted gas withdrawn from the second gas phase polymerization reactor is compressed in a compressor and said compressed gas is fed via a conveying gas line into an outlet between a first outlet vessel downstream of the first gas phase polymerization reactor and said second gas phase polymerisation reactor. Such a process can alleviate problems of malfunction, disturbances or plugging of the transfer lines and enables higher productivity and considerable saving of energy and equipment cost. Moreover, the production of alpha-olefin polymers with varying and tailored properties is possible.