Gas-Phase Polymerization Condensing Agent Ratios for Stickiness Control
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Solution Overview
Problem
Existing gas phase polymerization processes face challenges in balancing the use of condensing agents (CAs) to enhance cooling capacity while avoiding polymer stickiness, leading to suboptimal production rates and reactor shutdown risks, particularly due to varying reactor conditions and the need for real-time control.
Innovation Solution
A method for real-time calculation and adjustment of CA ratios using equivalence factors to maintain or increase stickiness temperature, balancing CA concentrations to optimize production rates without exceeding the stick limit (SL).
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If condensing agents are added to increase cooling capacity, then polymer production rate is improved, but polymer stickiness increases causing reactor shutdown
Solution Approach 1:
The patent implements dynamic adjustment of condensing agent ratios based on real-time reactor conditions. The system continuously monitors temperature, pressure, and production rate, then adjusts the CA composition dynamically to maintain optimal cooling while preventing stickiness. This transforms the static CA addition approach into a dynamic control system that adapts to changing reactor states.
Solution Approach 2:
The patent changes the chemical composition parameters of the condensing agent mixture by introducing equivalence factors that quantify the relative cooling effectiveness of different CAs. By adjusting the ratios of various condensing agents based on these factors, the system optimizes the cooling capacity-to-stickiness ratio, enabling higher production rates without exceeding stickiness thresholds.
2Temperature
If condensing agent concentration is increased to enhance heat transfer, then cooling capacity is improved, but polymer particles become cohesive and stick together
Solution Approach 1:
The patent modifies the compositional parameters of the condensing agent system by using equivalence factors to balance cooling effectiveness against stickiness induction. Different CAs have different equivalence factors that reflect their relative ability to provide cooling versus their tendency to cause stickiness. The system adjusts the mixture composition to optimize this trade-off, maintaining effective heat transfer while keeping polymer particles non-cohesive.
Solution Approach 2:
The patent employs composite condensing agent formulations consisting of multiple different CAs mixed in specific ratios determined by their equivalence factors. This composite approach allows the system to leverage the beneficial cooling properties of various CAs while mitigating the stickiness issues of individual components, achieving superior overall performance compared to single-CA systems.
3Productivity
If real-time control of CA composition is implemented, then production optimization is improved, but system complexity increases
Solution Approach 1:
The patent implements a feedback control system that continuously monitors reactor temperature, pressure, and production rate, then uses this information to adjust condensing agent composition in real-time. The equivalence factors provide a quantitative framework for translating sensor data into optimal CA ratio adjustments, creating a closed-loop control system that automatically optimizes production while preventing stickiness without requiring complex manual intervention.
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
Enhances polymer production rates by effectively managing CA compositions in real-time, preventing reactor shutdowns and ensuring stable operation.
Implementation Method 1
Cooling of the recycle stream to a temperature below the dew point temperature produces a two-phase gas/liquid mixture
Implementation Method 2
Vaporization of the liquid occurs when heat is added or pressure is reduced. Generally, the vaporization occurs when the two-phase mixture enters the fluidized bed, with the heat of polymerization providing the heat of vaporization
Implementation Method 3
since the polymerization reaction is exothermic, the amount of polymer produced in a fluidized bed polymerization process may be correlated to the amount of heat that can be withdrawn from the reaction zone
Data Source
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AI summary
This disclosure relates to processes for producing polyolefins in a gas phase reactor using condensing agent(s) (CAs), and real-time calculation of the ratio of one type of CA to another CA within a CA composition. This disclosure provides methods for controlling condensed phase cooling in a gas phase reactor used to polymerize olefins. The polymerization may employ one or more polymerization catalysts to polymerize one or more olefin monomers, and may include introducing a first condensing agent and a second condensing agent in a ratio of first condensing agent to second condensing agent, which ratio is calculated by ascertaining a stick limit for a first condensing agent, calculating an equivalence factor relating the first condensing agent and a second condensing agent, ascertaining a total allowable condensing agent, and calculating a first amount of the first condensing agent removed and replaced by a second amount of the second condensing agent.