Horizontal Polymerization Reactor Temperature Control
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Solution Overview
Problem
The production of propylene-based polymers in vapor-phase polymerization using horizontal reactors faces challenges with the generation of aggregated and fine powder polymers, leading to instability and reduced productivity due to inadequate heat removal and catalyst performance issues, especially when using highly activated or metallocene catalysts.
Innovation Solution
A method is developed to control temperature gradients within the reactor by setting specific temperature differences between areas and maintaining the catalyst feed part at a controlled dew point, utilizing the heat of vaporization of liquefied propylene for efficient heat removal, which stabilizes polymerization and reduces the formation of aggregated and fine powder polymers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If heat removal is insufficient in the catalyst feed part of a fluidized bed reactor, then polymerization activity increases, but temperature becomes unstable and aggregated polymer forms
Solution Approach 1:
The reactor is divided into multiple temperature control zones along the horizontal axis, with the catalyst feed part being a distinct zone. This segmentation allows independent temperature control in the catalyst feed region to prevent local heat accumulation while maintaining high polymerization activity.
Solution Approach 2:
Different temperature conditions are applied to different parts of the reactor. The catalyst feed part is maintained at a lower temperature (closer to dew point) to prevent aggregated polymer formation, while other regions can operate at higher temperatures for optimal polymerization activity.
2Reliability
If the inner wall temperature is cooled to the dew point or lower to inhibit aggregated polymer, then fluidized state is maintained, but operation control becomes difficult due to local phase change
Solution Approach 1:
The reactor operates in a dynamic regime where the temperature is maintained slightly above the dew point, preventing local phase change while maintaining fluidized state. This dynamic temperature control avoids the operational difficulties of cooling to or below dew point.
3Loss of energy
If heat of polymerization is removed utilizing heat of vaporization of liquefied propylene in a horizontal reactor, then heat removal efficiency increases, but temperature control precision becomes challenging
Solution Approach 1:
Multiple temperature sensors are placed at different positions along the horizontal reactor, and the system uses feedback control to adjust liquefied propylene flow rates dynamically. This maintains precise temperature control while utilizing vaporization heat removal.
4Productivity
If highly activated catalysts or metallocene catalysts are used to improve catalyst performance, then polymerization efficiency increases, but formation of aggregated polymer and fine powder increases
Solution Approach 1:
The temperature parameter in the catalyst feed region is optimized to be slightly above the dew point of propylene. This parameter change suppresses aggregated polymer formation by controlling the local thermal environment, while highly activated catalysts maintain high polymerization efficiency.
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
This approach enables stable production of propylene-based polymers with reduced fine powder formation and enhanced productivity by effectively managing temperature conditions and heat removal in the horizontal polymerization reactor, improving the operational stability and efficiency of the process.
Implementation Method 1
heat of polymerization is removed utilizing heat of vaporization of liquefied propylene
Data Source
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AI summary
An object is to develop a method for stably producing a propylene-based polymer together with inhibiting generation of an aggregated polymer, reducing a generation amount of fine powder, and thereby enhancing production efficiency. The present invention relates to a method for producing a propylene-based polymer, comprising polymerizing propylene or propylene and an α-olefin except propylene in the presence of a catalyst using a horizontal polymerization reactor equipped with a stirrer rotating around a horizontal axis in the inside of the reactor by a continuous vapor-phase polymerization method in which heat of reaction is removed by heat of vaporization of liquefied propylene, wherein the reactor can set a plurality of area sections different in temperature in a horizontal axis direction in the inside of the reactor and at least one of the following requirements (A) and (B) is satisfied: requirement (A): temperature difference ΔT1 (°C) (= Tω - Tα) between temperature (Tα) of an area section including an upstream end of the reactor and temperature (Tω) of an area section including a downstream end thereof is 0.1 to 20°C; requirement (B): temperature difference ΔT2 (°C) (= Tx - Tz) between temperature (Tx) of an area section including a catalyst feed part and dew point (Tz) of mix gas in the reactor is 0 to 5°C.