Slurry Loop Reactor Swelling Control via Dilution
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Solution Overview
Problem
In slurry loop polymerization, high solid content leads to instability known as the 'swelling phenomenon', characterized by rapid fluctuations in process variables like pump power, which can cause safety shut-downs and reduce reactor efficiency, making it challenging to operate close to stability boundaries while maximizing productivity and product quality.
Innovation Solution
The method involves monitoring plant control measurements for increasing fluctuations, identifying the onset of swelling through signal processing, and controlling the reactor medium dilution to maintain the system at the onset of swelling, thereby preventing instability and optimizing solids concentration and yield.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high solid content is used to increase polymerization kinetics and productivity, then catalyst productivity and polymer production increase, but pump power fluctuations increase causing swelling instability and safety shut-downs
Solution Approach 1:
The system performs preliminary detection of swelling conditions by monitoring plant control measurements and their fluctuations before actual swelling occurs. When fluctuations exceed a threshold, the system pre-emptively adjusts operating parameters (monomer feed rate, reactor temperature, solids concentration) to prevent swelling instability, thereby maintaining both high productivity and process reliability
Solution Approach 2:
The system implements continuous feedback control by monitoring plant control measurements (pump power, reactor temperature, slurry density) and their fluctuations in real-time. When fluctuations indicate approaching swelling conditions, the control system automatically adjusts operating parameters to maintain stability while maximizing productivity, creating a closed-loop control mechanism that balances both objectives
2Productivity
If high monomer and comonomer concentration is used to increase polymerization kinetics, then polymer production increases, but pump power fluctuations increase leading to swelling phenomenon
Solution Approach 1:
The system allows monomer and comonomer concentrations to be increased to enhance polymerization kinetics and productivity, but implements partial control by monitoring fluctuations and making selective adjustments. When fluctuations remain within acceptable ranges, high concentrations are maintained for maximum productivity; when thresholds are approached, the system partially reduces concentrations or adjusts other parameters to eliminate harmful fluctuations while preserving overall high production rates
3Productivity
If high temperature is used to increase polymerization kinetics, then reaction rate and polymer production increase, but process instability increases causing swelling and safety shut-downs
Solution Approach 1:
The system implements dynamic temperature control where the reactor temperature is continuously adjusted based on real-time monitoring of plant control measurements and their fluctuations. The temperature profile is made adaptive rather than static, allowing higher temperatures to maximize polymerization kinetics when stable, but automatically adjusting to prevent swelling instability, thereby dynamically balancing productivity and process stability
4Productivity
If operation is pushed close to stability boundary to maximize productivity, then polymer production increases, but risk of swelling instability and safety shut-downs increases
Solution Approach 1:
The system performs preliminary detection of swelling conditions by analyzing fluctuations in plant control measurements before actual swelling occurs. By identifying early warning signs of instability, the system takes pre-emptive action to adjust operating parameters and move away from the instability boundary, thereby maintaining high productivity while preventing harmful swelling events
Data Source
AI summary
The present invention discloses a method for controlling the onset and development of swelling in a slurry loop reactor by progressively diluting the reactor, the amount of dilution being driven by the amplitude of the fluctuations measured on some plant measurement.