Fluidized Bed Polymerization Reactor Pressure Control
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Solution Overview
Problem
Existing methods for controlling fluidized bed gas phase polymerization reactors fail to effectively combine production rate control based on feed flow rates with pressure control, leading to potential thermal instability and suboptimal production.
Innovation Solution
A control method that integrates production rate control with pressure control by calculating a set point production rate based on detected pressure and monomer compositions, adjusting monomer feed rates to maintain desired pressure and maximize production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If catalyst flow rate is manipulated to control production rate, then production rate increases, but thermal stability deteriorates when polymerization heat exceeds thermal exchange capacity
Solution Approach 1:
The patent changes the controlled parameter from catalyst flow rate to monomer feed flow rate. By controlling the amount of monomer supplied to the reactor rather than the catalyst amount, the system can regulate polymerization heat generation while maintaining production rate. This parameter substitution resolves the contradiction by enabling independent control of thermal balance and productivity.
2Productivity
If monomer feed rate is increased to maximize production, then productivity increases, but pressure control becomes difficult leading to operational instability
Solution Approach 1:
The patent implements a feedback control system where reactor pressure is continuously monitored and used to adjust monomer feed rate. The control method calculates a set-point monomer feed flow rate based on the difference between actual and target pressure, creating a closed-loop system that automatically balances production maximization with pressure stability.
3Productivity
If reactor is operated close to plant capacity limits for economic efficiency, then productivity increases, but process safety and stability deteriorate
Solution Approach 1:
The patent calculates a set-point monomer feed flow rate in advance based on target production rate and current reactor conditions before actual polymerization occurs. This preliminary calculation allows the system to proactively adjust feed rates to maintain optimal operating conditions, preventing instability before it occurs rather than reacting to problems after they arise.
Data Source
Figure 1
AI summary
A control method for controlling a fluidized bed polymerisation reactor in the production of a given polymer product, the method comprising the following steps: (a) determining a ratio of the production rate of the polymer product in the reactor to the pressure in the reactor, (b) setting a production rate of the polymer product in the reactor which production rate, on the basis of said ratio of step (a), corresponds to a desired pressure in the reactor; (c) adjusting the feed rates of monomers into the reactor in accordance with said set point production rate.