Multimodal HDPE Reactor Control for Continuous Operation
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Solution Overview
Problem
The formation of polymer chunks in the second reactor during the production of multimodal high density polyethylene (HDPE) leads to damage in rotating machinery and requires reactor shutdown for cleaning and maintenance, disrupting the manufacturing process.
Innovation Solution
A method and system that allow for the detection of process upsets in the second reactor, enabling the transfer of the polymerization process to a standby third reactor, allowing for maintenance without shutting down the system, by monitoring for anomalies and controlling the slurry transfer between reactors using a control unit and valve system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the second reactor is used for second stage polymerization to achieve bimodal HDPE, then the molecular weight distribution with higher median value is obtained, but polymer chunks form causing damage to rotating machinery and requiring shutdown for cleaning
Solution Approach 1:
The patent divides the second reactor system into multiple independent reactor vessels (second reactor and third reactor) that can operate separately. When polymer chunks form in the second reactor, the process can be switched to the third reactor, allowing the second reactor to be cleaned and maintained without shutting down the entire production line. This segmentation enables continuous operation while maintaining product quality.
2Ease of repair
If standard cleaning procedures are used for the second reactor, then cleaning and maintenance can be performed, but the manufacturing process must be shut down
Solution Approach 1:
The patent prepares a third reactor in advance as a standby unit, keeping it ready to immediately take over when the second reactor requires cleaning. This preliminary preparation ensures that no production time is lost during maintenance operations, as the alternative reactor is already configured and ready to operate.
Solution Approach 2:
The patent implements a switching mechanism that allows continuous HDPE production by transferring the polymerization process from the second reactor to the third reactor when needed. This ensures that the useful action of producing bimodal HDPE continues uninterrupted while one reactor undergoes maintenance.
3Productivity
If a third standby reactor is added to the system, then continuous operation during maintenance is enabled, but the system complexity increases
Solution Approach 1:
The third reactor is designed with the same capabilities and configuration as the second reactor, making it a universal replacement unit. This multi-functionality allows either reactor to perform the second stage polymerization, simplifying the control logic and making the system more flexible rather than more complex.
Data Source
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AI summary
A method of controlling a process of manufacturing multimodal high density polyethylene, comprising performing first polymerization to form a first slurry in a first reactor, transferring at least part of the first slurry from the first reactor into a second reactor, performing second polymerization to form a second slurry in the second reactor, transferring at least part of the second slurry from the second reactor to a further process stage, maintaining a third reactor in a stand-by mode, monitoring the second polymerization in the second reactor for detecting a process upset in reactor, upon detecting a process upset in reactor interrupting the transfer of at least part of the first slurry from the first reactor into the second reactor, transferring at least part of the first slurry from the first reactor into the third reactor, performing second polymerization to form the second slurry in the third reactor. Cleaning the second reactor after it has been taken out of operation, and placing the second reactor in stand-by mode, in case a disturbance is detected in reactor three.