Polymer Particle Transfer via Intermediary Pressure Chambers
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Solution Overview
Problem
The transfer of polymer particles between upstream and downstream reactors in polymerization processes is hindered by agglomeration and back-mixing issues, particularly in subfluidized particulate beds, where sticky polymers tend to compact and fail to flow freely, necessitating improved methods for efficient particle transfer while maintaining independent operating conditions.
Innovation Solution
A process involving the discharge of polymer particles and reactive gases into a first chamber, followed by transfer to a second chamber at significantly lower pressure, allowing degassing of absorbed monomer and separation of hydrogen, before isolating and transferring the particles to a downstream vessel, utilizing pressure differentials for efficient particle movement without supplemental purge gas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If polymer particles are transferred directly between reactors using conventional methods, then transfer can occur, but agglomeration and back-mixing occur reducing transfer efficiency
Solution Approach 1:
The patent introduces an intermediary transfer chamber that acts as a buffer between the upstream and downstream reactors. Polymer particles are transferred to this intermediate chamber first, where they can be held and their pressure adjusted before final transfer to the downstream reactor. This intermediary space prevents direct contact between reactor streams, reducing back-mixing and agglomeration while maintaining transfer efficiency.
Solution Approach 2:
The transfer process is segmented into distinct stages: transfer from upstream reactor to transfer chamber, pressure adjustment in transfer chamber, then transfer to downstream reactor. This segmentation allows independent control of each transfer stage, enabling optimization of conditions to prevent agglomeration while maintaining high transfer efficiency.
2Speed
If pressure differential is used to drive particle transfer, then transfer speed increases, but hydrogen and reactive gases transfer with particles to downstream reactor
Solution Approach 1:
The transfer chamber serves as an intermediary that decouples the pressure differential driving force from the particle transfer to the downstream reactor. High pressure differential can be used to rapidly transfer particles to the transfer chamber, then a controlled, lower pressure differential is used for transfer to the downstream reactor, preventing excessive hydrogen co-transfer while maintaining fast overall transfer speed.
Solution Approach 2:
The system performs preliminary transfer of polymer particles to the transfer chamber before final transfer to the downstream reactor. This preliminary action allows separation of the high-speed transfer function (to transfer chamber) from the controlled transfer function (to downstream reactor), enabling fast transfer while minimizing hydrogen loss.
3Adaptability or versatility
If reactors operate at independent conditions, then process flexibility increases, but particle transfer between reactors becomes more difficult
Solution Approach 1:
The transfer chamber acts as a mediator that buffers the pressure and composition differences between independently operating reactors. By providing this intermediate buffer zone, the system can accommodate independent reactor operating conditions without requiring complex real-time coordination, simplifying the overall control system while maintaining flexibility.
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 method effectively separates hydrogen from polymer particles, reduces agglomeration risks, and allows for independent operation of upstream and downstream reactors, enhancing the transfer efficiency and flexibility in reactor placement, while minimizing hydrogen transfer to the downstream reactor.
Implementation Method 1
transferred to a second chamber which is at a pressure which is at least 600 kPa below the operating pressure of the upstream reactor
Implementation Method 2
allowing degassing of absorbed monomer and separation of hydrogen
Data Source
AI summary
The present invention relates to a process for polymerization of a monomer, and in particular whereby polymer particles are transferred from an upstream polymerization reactor, which process comprises:(a) discharging a mixture comprising polymer particles and reactive gases, which reactive gases comprise hydrogen, from the upstream reactor,(b) transferring the polymer particles and reactive gases into a first chamber which is in open communication with a second chamber during the transfer such that the polymer particles pass through the first chamber into the second chamber,(c) keeping the first and second chamber in open communication for a time period, t, after completing transfer of the polymer particles to the second chamber, and(d) subsequently isolating the second chamber from the first chamber and transferring the polymer particles from the second chamber into a downstream vessel.