Agglomerate Trap Valve Timing for Fluidized Bed Reactors
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Solution Overview
Problem
There is a need to withdraw polymer agglomerates from a fluidized bed polymerization reactor during the polymerization process, as existing methods are inefficient and can lead to process upsets when agglomerates grow too large.
Innovation Solution
A method and system for withdrawing polymer agglomerates from a fluidized bed reactor without a fluidization grid, utilizing a conical bottom zone, an agglomerate trap with valves, and a control system to measure agglomerate content and adjust valve opening times for efficient removal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If agglomerates are withdrawn only after reactor shut-down, then the reactor structure can be simple, but the productivity is reduced due to process interruption
Solution Approach 1:
The reactor is segmented into distinct zones: a fluidized bed zone for polymerization and a separate agglomerate trap zone for removal. This segmentation allows continuous operation by enabling agglomerate removal from the trap without interrupting the polymerization process in the fluidized bed zone
Solution Approach 2:
The agglomerate trap serves as an intermediary device between the fluidized bed and the discharge system. It temporarily collects agglomerates that fall through the fluidized bed, allowing them to be removed periodically without disrupting the continuous polymerization process
2Reliability
If agglomerates are removed frequently, then the polymerization process stability is improved, but the loss of time for valve operations increases
Solution Approach 1:
A measurement system continuously monitors the agglomerate content in the trap and provides feedback to the control system. The control system adjusts the valve opening timing based on this feedback, opening valves only when agglomerate content reaches thresholds that require removal, thereby optimizing the balance between process stability and operational time loss
Solution Approach 2:
The valve opening duration is dynamically adjusted based on measured agglomerate content. Rather than using fixed timing, the system adapts the valve opening time to the actual agglomerate accumulation rate, reducing unnecessary valve operations while maintaining process stability
3Loss of time
If large agglomerates are allowed to accumulate, then the loss of time for removal is reduced, but the harmful factors increase due to process upsets
Solution Approach 1:
The measurement system detects agglomerate content and triggers valve opening at appropriate thresholds, preventing excessive accumulation that would cause process upsets while minimizing unnecessary removal operations
Solution Approach 2:
The system performs preliminary measurement and assessment of agglomerate content before initiating removal operations, ensuring that valves are opened at the optimal moment when agglomerate accumulation reaches levels that require intervention but before they cause process disruptions
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
Enables smooth operation by removing agglomerates before they cause process disruptions, ensuring continuous polymerization and preventing downstream issues without reactor shutdown.
Implementation Method 1
a bottom zone having a generally conical shape in direct contact with and below the middle zone and wherein a base of a fluidised bed is formed, and an agglomerate trap below the bottom zone
Implementation Method 2
measuring a value of a process variable indicative of the content of agglomerates in the agglomerate trap; and adjusting the opening time of the first valve or the second valve or both the first valve and the second valve based on the measured value
Data Source
AI summary
The present invention relates to a process and apparatus for withdrawing polymer agglomerates from a fluidised bed polymerisation reactor, the polymerisation reactor comprising a bottom zone having a generally conical shape and no fluidisation grid. The agglomerates are withdrawn by using an agglomerate trap below the bottom zone. A value of a process variable indicative of the content of agglomerates in the agglomerate trap is measured and the opening time of the valves transferring polymer to and from the agglomerate trap is adjusted based on the measured value.